United States Department of Agriculture

Forest 

Service

Pacific Northwest 

Research Station

General Technical Report

PNW-GTR-907

October 

2017

Terrestrial Species Viability 

Assessments for National Forests 

in Northeastern Washington

William L. Gaines, Barbara C. Wales, Lowell H. Suring, James S. Begley, 

Kim Mellen-McLean, and Shawne Mohoric
In accordance with Federal civil rights law and U.S. Department of Agriculture 

(USDA) civil rights regulations and policies, the USDA, its Agencies, offices, and 

employees, and institutions participating in or administering USDA programs are 

prohibited from discriminating based on race, color, national origin, religion, sex, 

gender identity (including gender expression), sexual orientation, disability, age, 

marital status, family/parental status, income derived from a public assistance 

program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any 

program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident. 

Persons with disabilities who require alternative means of communication for 

program information (e.g., Braille, large print, audiotape, American Sign Language, 

etc.) should contact the responsible Agency or USDA’s TARGET Center at (202) 

720-2600 (voice and TTY) or contact USDA through the Federal Relay Service 

at (800) 877-8339. Additionally, program information may be made available in 

languages other than English. 

To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at http://www.ascr.usda.gov/complaint_filing_cust.html and at any USDA office or write a letter addressed to USDA 

and provide in the letter all of the information requested in the form. To request a 

copy of the complaint form, call (866) 632-9992. Submit your completed form or 

letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant 

Secretary for Civil Rights, 1400 Independence Avenue, SW, Washington, D.C. 

20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov. 

USDA is an equal opportunity provider, employer, and lender.

Authors

William L. Gaines is a wildlife ecologist, Washington Conservation Science Institute, 12725 Wilson St., Leavenworth, WA 98826, formerly wildlife ecologist, U.S. 

Department of Agriculture, Forest Service, Okanogan-Wenatchee National Forest, 

215 Melody Lane, Wenatchee, WA 98801. Barbara C. Wales is a wildlife biologist, U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station, Forestry and Range Sciences Laboratory, 1401 Gekeler Lane, La Grande, 

OR 97850. Lowell H. Suring is a wildlife ecologist (retired), Northern Ecologic, 

LLC, 10685 County Road A, Suring, WI 54174, formerly wildlife ecologist, U.S. 

Department of Agriculture, Forest Service, Intermountain Region, Boise National 

Forest, 324 24th St., Ogden, UT 84401. James S. Begley is a spatial analyst, Washington Conservation Science Institute, 3414 N Verde St., Tacoma, WA 98407. Kim 

Mellen-McLean is a wildlife ecologist (retired) and Shawne Mohoric is a regional 

planner (retired), U.S. Department of Agriculture, Forest Service, Pacific Northwest 

Region, 1220 SW 3rd, Portland, OR 97204.
Abstract

Gaines, William L.; Wales, Barbara C.; Suring, Lowell H.; Begley, James S.; 

Mellen-McLean, Kim; Mohoric, Shawne. 2017. Terrestrial species viability 

assessments for national forests in northeastern Washington. Gen. Tech. Rep. 

PNW-GTR-907. Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station. 324 p. 

We developed a process to address terrestrial wildlife species for which management for ecosystem diversity may be inadequate for providing ecological conditions 

capable of sustaining viable populations. The process includes (1) identifying 

species of conservation concern, (2) describing source habitats, and other important 

ecological factors, (3) organizing species into groups, (4) selecting surrogate species 

for each group, (5) developing surrogate species assessment models; (6) applying 

surrogate species assessment models to evaluate current and historical conditions, 

(7) developing conservation considerations, and (8) designing monitoring and adaptive management. Following the application of our species screening criteria, we 

identified 209 of 700 species as species of concern on National Forest System lands 

east of the Cascade Range in Washington state. We aggregated the 209 species 

of conservation concern into 10 families and 28 groups based primarily on their 

habitat associations (these are not phylogenetic families). We selected 32 primary 

surrogate species (78 percent birds, 17 percent mammals, 5 percent amphibians) 

for application in northeastern Washington, based on risk factors and ecological 

characteristics. Our assessment documented reductions in habitat capability across 

the assessment area compared to historical conditions. We combined management 

considerations for individual species with other surrogate species to address multiple species. This information may be used to inform land management planning 

efforts currently underway on the Okanogan-Wenatchee and Colville National 

Forests in northeastern Washington.

Keywords: Viability assessments, northeastern Washington, surrogate species, 

conservation considerations.
ii

Summary

Regulations and directives associated with enabling legislation for management 

of national forests require maintenance of viable populations of native and desired 

nonnative wildlife species. Broad-scale assessments that address ecosystem diversity may cover assessment of viability for most, but not all, species. We developed 

a process to address those species for which management for ecosystem diversity 

may be inadequate for providing ecological conditions capable of sustaining viable 

populations. The process includes (1) identifying species of conservation concern; 

(2) describing source habitats and other important ecological factors; (3) organizing 

species into groups; (4) selecting surrogate species for each group; (5) developing 

surrogate species assessment models; (6) applying surrogate species assessment 

models to evaluate current and historical conditions; (7) developing conservation 

considerations; and (8) designing monitoring and adaptive management strategies. 

Following the application of our species screening criteria, we identified 209 of 700 

species as species of concern on National Forest System lands east of the Cascade 

Range in Washington. We aggregated the 209 species of conservation concern into 

10 families and 28 groups based primarily on their habitat associations (these are 

not phylogenetic families). We selected 32 primary surrogate species (78 percent 

birds, 17 percent mammals, 5 percent amphibians) for application in northeastern 

Washington, based on risk factors and ecological characteristics. Our assessment 

documented reductions in the viability outcomes for all surrogate species compared 

to historical conditions. The species for which current viability outcomes were most 

similar to historical viability outcomes included the golden eagle, harlequin duck, 

northern goshawk, peregrine falcon, and Wilson’s snipe. Species for which current 

viability outcomes have departed the most from historical viability outcomes and 

are of greatest concern included the eared grebe, fox sparrow, sage thrasher, western bluebird, and white-headed woodpecker. To address such changes, we identified conservation considerations for each surrogate species that included habitat 

protection and restoration and amelioration of risk factors. We combined individual 

species with other surrogate species and with management proposals for other 

resources (e.g., recreation, fire, and fuels management) to develop multispecies, 

multiresource management considerations. The information generated from our 

approach could be used to inform land management planning to help improve the 

probability that desired population outcomes will be achieved. However, practitioners should note that a conservation planning process, such as ours, cannot remove 

all uncertainty and risk to species viability, warranting an adaptive management 

approach.
iii

Contents

1 Chapter 1: Terrestrial Species Viability Assessments: Process and 

 Overall Results

1 Introduction

3 Terrestrial Species Viability Assessment Process

4 Identifying Species of Conservation Concern

5 Definition of Source Habitats

9 Grouping Species of Conservation Concern

10 Identifying the Ecological Relationships of Species of Conservation Concern

10 Risk Factors

10 Fine-Scale Habitats

10 Home Range and Dispersal Information

11 Species Range Across the Assessment Area

12 Selection of Surrogate Species

15 Development of Surrogate Species Assessment Models

18 Reference Conditions for Source Habitats

19 Reference Conditions of Forested Source Habitats

19 Reference Conditions of Postfire Source Habitats

20 Reference Conditions for Species Associated With Nonforested

Source Habitats

21 Reference Conditions for Wetland and Riparian Source Habitats

21 Reference Conditions for Streamside Riparian and Cliff Source Habitats

22 Factors That Influenced Habitat Quality

25 Risk Factors

26 Viability Outcomes

28 Weighted Watershed Index Calculation

29 Habitat Distribution Index

29 Dispersal Habitat Suitability

30 Viability Outcomes for Surrogate Species

34 Habitat Conditions for Conservation Planning

35 Overall Results of the Surrogate Species Assessments

36 Surrogate Species Assessment Model Evaluation
iv

41 Chapter 2: Individual Surrogate Species Assessments

41 American Marten

41 Introduction

41 Model Description

49 Management Considerations

49 Bald Eagle

49 Introduction

49 Model Description

53 Assessment Results

54 Management Considerations

55 Bighorn Sheep

55 Introduction

55 Model Description

59 Assessment Results

61 Management Considerations

62 Black-Backed Woodpecker

62 Introduction

62 Model Description

65 Assessment Results

69 Management Considerations

69 Canada Lynx

69 Introduction

69 Model Description

73 Assessment Results

76 Management Considerations

77 Cassin’s Finch

77 Introduction

77 Model Description

78 Assessment Results

81 Management Considerations

82 Columbia Spotted Frog
v

82 Introduction 83 Model Description

87

Assessment Results

90

Management Considerations

90Eared Grebe

90 Introduction

90 Model Description

94Assessment Results

97Management Considerations

97

Fox Sparrow

97 Introduction

97 Model Description

99

Assessment Results

102

Management Considerations

103

Golden Eagle

103 Introduction

103 Model Description

110Assessment Results

113Management Considerations

114 Harlequin Duck

114

Introduction

114 Model Description

117Assessment Results

119Management Considerations

119

Larch Mountain Salamander

119 Introduction

120Management Considerations

120

Lark Sparrow

120 Introduction

120 Model Description

123

Assessment Results

127Management Considerations
vi

127 Lewis’s Woodpecker 

127 Introduction

127 Model Description

130 Assessment Results

133 Management Considerations

134 MacGillivray’s Warbler

134 Introduction

134 Model Description

136 Surrogate Species Assessment Results

139 Management Considerations

139 Marsh Wren

139 Introduction

139 Model Description

142 Assessment Results

144 Management Considerations

145 Northern Bog Lemming

145 Introduction

145 Management Considerations

146 Northern Goshawk

146 Introduction

146 Model Description

149 Assessment Results

152 Management Considerations

152 Northern Harrier

152 Introduction

152 Model Description

156 Assessment Results

158 Management Considerations

158 Peregrine Falcon

158 Introduction

159 Model Description

162 Model Evaluation
vii

162Assessment Results

164Management Considerations

164

Pileated Woodpecker

164 Introduction

165 Model Description

168

Assessment Results

170Management Considerations

171Sage Thrasher

171 Introduction

171 Model Description

174Assessment Results

177Management Considerations

178

Tailed Frog

178 Introduction

178 Model Description

181

Assessment Results

184Management Considerations

184Tiger Salamander

184 Introduction

185 Model Description

188

Assessment Results

191

Management Considerations

191Townsend’s Big-Eared Bat 

191 Introduction

192

Management Considerations

192Various Bat Species

192 Introduction

199

Management Considerations

200

Western Bluebird

200 Introduction

200 Model Description

205Management Considerations
viii

205 Western Gray Squirrel

205 Introduction

207 Management Considerations

208 White-Headed Woodpecker

208 Introduction

208 Model Description

211 Assessment Results

214 Management Considerations

215 Wilson’s Snipe

215 Introduction

215 Model Description

216 Assessment Results

219 Management Considerations

219 Wolverine

219 Introduction

219 Model Description

223 Assessment Results

226 Management Considerations

226 Wood Duck

226 Introduction

227 Model Description

229 Assessment Results

231 Management Considerations

233 Chapter 3: Multispecies Conservation

233 Introduction

235 Conservation Emphasis Areas

235 Aquatic and Riparian Habitat Conservation Emphasis Area

236 Snag and Down Wood Conservation Emphasis Area

236 Forested Habitats Conservation Emphasis Areas

241 Human Access Emphasis Area

242 Domestic Grazing Emphasis Area
ix

242 Invasive Species Emphasis Area

245 Chapter 4: Monitoring and Adaptive Management

246 Surrogate Species Monitoring Priorities Based on Viability Outcomes

247 Metric Equivalents

248 Literature Cited

317 Appendix 1: Common and Scientific Names

318 Appendix 2: Species of Conservation Concern

325 Appendix 3: Members of Working Groups
1

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Chapter 1: Terrestrial Species Viability

Assessments: Process and Overall Results

Introduction 

The National Forest Management Act (NFMA) of 1976 (Public Law 94-588) and 

the Multiple-Use Sustained-Yield Act of 1960 (Public Law 86-517) require maintenance of diversity and sustainability of plant and animal communities on National 

Forest System lands throughout the United States (Marcot and Murphy 1996). 

Associated regulations and directives call for providing viable populations of native 

and desired nonnative wildlife with an emphasis on those species considered to be 

at risk (Suring et al. 2011). The assessment of population viability for species of 

concern is one component of an evaluation of ecosystem sustainability (Linder et al. 

2004). Comprehensive analyses of ecosystem sustainability may be accomplished 

through a hierarchical approach that addresses ecosystem diversity and species 

diversity. Guidance on the assessment of species diversity within the Pacific Northwest Region of the U.S. Department of Agriculture, Forest Service was developed 

to help improve efficiencies, reduce costs by eliminating redundancy in analyses, 

provide a forum for a rigorous science review of the process, and provide consistency across the region as national forests or groups of national forests revise their 

land and resource management plans (USDA FS 2006). This document presents 

the application of the regional guidance to the northeast Washington state assessment area, a cluster of two national forests that are among the first in the Pacific 

Northwest Region to revise their land and resource management plans. We defined 

the assessment area to include all of the watersheds (5th-level hydrologic unit code 

[HUC]) that contained any amount of Forest Service land under the management 

of the Okanogan-Wenatchee or Colville National Forests. We defined the plan area 

as the combined land managed by the Okanogan-Wenatchee and Colville National 

Forests, a subset of the assessment area (fig. 1).

This document presents a process that was developed under the 1982 Planning 

Rule (Section 219.27, as amended in 1983). However, the process is consistent with 

the 2012 Planning Rule (36 CFR 219.9(b)) and associated directives (FSH 1909.12 

chapter 10, 12.5). 

The initial focus of our application of the assessment process was an evaluation of ecosystem diversity, which considered the maintenance of functioning 

native ecosystems within the assessment area, and the extent to which maintaining 

ecosystem diversity will also sustain populations of animal species within their 

ranges in the plan area (Samson 2002, Samson et al. 2003). This is referred to as a 

“coarse-filter” approach to conservation (Baydeck et al. 1999, Hunter et al. 1988, 
2

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 1—Area of the Okanogan-Wenatchee and Colville National Forests that makes up the 

northeast Washington planning area.

Landres et al. 1999, Samson 2002, Samson et al. 2003). The coarse-filter evaluation 

of ecosystem diversity generally compares the amount and distribution of existing 

vegetation communities to a set of reference conditions (e.g., pre-European settlement, historical range of variability [HRV]) to evaluate current representation of 

vegetation communities across the plan area (Samson 2002). For national forests 

located within the interior Columbia Basin, coarse-filter assessments were completed as part of the Interior Columbia Basin Ecosystem Management Project 

(ICBEMP) (Hann et al. 1997, Hessburg et al. 1999a). These assessments included 

evaluations of existing vegetation communities compared to the HRV and of 

changes that have occurred in the amount, effectiveness, and connectivity of 

habitats for surrogate wildlife species (Hessburg et al. 1999a, Lehmkuhl et al. 2001, 

Raphael et al. 2001, Wisdom et al. 2000).

The 2012 planning rule uses a coarse-filter approach by managing for “ecological sustainability” (36 CFR 219.8) along with “ecosystem plan components” 

to maintain and restore ecosystem integrity (36 CFR 219.9 (a)). The directives 

associated with the 2012 Rule suggest the use of natural range of variation (NRV) 

as the ecological reference model (FSH 1909.12 ch10 12.14a). This coarse-filter 

approach is intended to provide appropriate conditions to maintain most species. 
3

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

A complementary approach to a coarse-filter analysis is necessary for species for 

which ecological conditions needed to maintain populations may not be completely 

provided for by merely maintaining ecosystem diversity (Samson 2002). For 

example, species associated with fine-scale ecosystem components (Samson 2002) 

or habitat generalists influenced by human activities such as roads (Carroll et al. 

2001) may not be adequately addressed by a broad-scale assessment of vegetation 

conditions (Cushman et al. 2007). In these cases, a species-specific approach to the 

analysis and establishment of plan direction may be necessary. The assessment of 

individual species is a “fine-filter” approach to conservation (Andelman et al. 2001, 

2004; Holthausen et al. 1999, Holthausen 2002, Samson et al. 2003). Holthausen 

(2002) and Andelman et al. (2001) provided valuable suggestions on how to conduct 

assessments of species diversity. In addition, Forest Service regulations (36 CFR 

219.9) and directives, (FSH 1909.12 chapter 10, 12.5) and regional guidance (USDA 

FS 2006) provide guidelines for conducting assessments of the viability of species 

of conservation concern. 

This document details the terrestrial species assessment process, results of the 

assessment, and the management considerations for the conservation of key elements of terrestrial diversity. The document is divided into four chapters: chapter 1 

presents the assessment process and summarizes overall results, chapter 2 presents 

results and management considerations for the individual surrogate species, chapter 

3 brings together results of the individual surrogate species assessment into multispecies assessment, and chapter 4 discusses priorities for monitoring based on 

assessment results, general monitoring methods, and how results can be used in an 

adaptive management framework.

Terrestrial Species Viability Assessment Process

The process we used to assess the viability of terrestrial species included the 

following major steps (Suring et al. 2011):

• Identify species of conservation concern

• Define source habitats for species of conservation concern 

• Group species of conservation concern

• Identify the ecological relationships of species of conservation concern

• Select surrogate species

• Develop surrogate species assessment models

• Assess viability outcomes for surrogate species

• Evaluate habitat conditions for conservation planning

This document 

details the terrestrial 

species assessment 

process, results of 

the assessment, and 

the management 

considerations for the 

conservation of key 

elements of terrestrial 

diversity.
4

GENERAL TECHNICAL REPORT PNW-GTR-907

Identifying Species of Conservation Concern

A process for identifying the full set of species for a geographic area that may be 

at risk because of future management actions is very complex, and a universally 

accepted approach is not available (Holthausen et al. 1999, Raphael and Marcot 

1994). Numerous approaches are applied by natural resource management agencies 

to classify species according to their risk of extirpation or extinction at regional 

(Breininger et al. 1998, Lunney et al. 1996, Millsap et al. 1990), national (Czech and 

Krausman 1997, Molloy and Davis 1992), and international (IUCN 2000) scales. 

Andelman et al. (2004) recommended using the global species ranks from the 

Natural Heritage Program (Master 1991, Master et al. 2000) as a system appropriate 

for use by the Forest Service to address the agency’s legal requirements (Holthausen 

et al. 1999, Raphael and Marcot 1994). They recommended using these rankings 

because many of the species that occur on National Forest System lands have been 

evaluated, the database with species ranks is readily available, and the Natural 

Heritage Program process may be the most suitable existing protocol for identifying 

species of concern. However, Andelman et al. (2004) noted that the initial protocol 

used by the Natural Heritage Program to rank species (Master 1991, Master et al. 

2000) did not explicitly incorporate weightings for threats.

We developed a process to identify species of conservation concern (Suring 

et al. 2011). Our process is consistent with the 2012 planning rule and associated 

directives for identifying species-at-risk and species of conservation concern (SCC) 

(FSH 1909.12 chapter 10, 12.52).

We identified the following criteria to identify SCC:

1. Species listed as endangered, threatened, candidate, or proposed under the 

U.S. Endangered Species Act.

2. Species that had been petitioned for listing under the U.S. Endangered 

Species Act and have received a determination of “may be warranted” or 

“warranted but precluded.”

3. Species with the following ranks from the Natural Heritage Program as 

documented on NatureServe (2009):

a. G-1 through G-3.

b. Intraspecific (subspecific) taxa with ranks of T-1 through T-3.

c. S-1 through S-3.

4. Species listed by Washington Department of Fish and Wildlife as threatened or endangered.

5. Species on the U.S. Fish and Wildlife Service birds of conservation concern 

national priority list (U.S. Fish and Wildlife Service 2002).
5

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

6. Bird species in the Partners in Flight species assessment database (http://

www.rmbo.org/pif/pifdb.html) with scores indicating a moderate to large 

population decline or severe to extreme threats to populations (Carter et al. 

2000). 

7. Species identified as a “terrestrial vertebrate species of focus” from the 

ICBEMP (Lehmkuhl et al. 1997, Wisdom et al. 2000). Species from the 

ICBEMP list were included unless they met one or more of the following 

criteria:

a. Wisdom et al. (2000) concluded a positive or no change in source habitats in the ecological reporting units (ERU) overlapping Washington, 

and no other published reasons for concern were found.

b. If a more recent assessment of populations (e.g., breeding bird survey 

data) or expert opinion was available that indicated there was not a current reason for concern. 

8. Species described by Raphael et al. (2001) as having fragmented populations that are currently vulnerable to extirpation or extinction, especially if 

they were abundant historically.1

9. Species listed by Washington state as strategy species in its comprehensive 

wildlife conservation strategies.

The focus in the application of this process was on species that are of regional 

or local conservation concern as indicated by documented risks to populations or 

habitats. All native terrestrial vertebrates known to occur on land managed by the 

Forest Service east of the crest of the Cascade Range in Washington were evaluated. Accidental species were not included nor were extirpated species without 

near-term plans or opportunities for reintroduction. Note that this process does 

not include species of public interest for hunting, trapping, or other consumptive 

or commercial uses unless their populations were determined to be at risk (e.g., 

bighorn sheep).

Definition of Source Habitats

Concerns have been raised about using habitat as an indicator of how populations may respond to environmental changes. For example, Cushman et al. (2007) 

evaluated the use of cover type or successional stage to predict the abundance of 

1

 Species with a population outcome of D or E under the current condition scenario, or 

outcome C with a decline from an historical outcome of A or B on National Forest System 

or Bureau of Land Management lands as defined in Raphael et al. (2001).
6

GENERAL TECHNICAL REPORT PNW-GTR-907

birds in a forested environment and found that either variable used alone was a poor 

predictor. When they used cover type and successional stage in combination, as 

we did, they found more reliable predictions, although the accuracy varied among 

bird guilds. They concluded that while habitat-relationship models are a necessary 

guide for management and conservation, they do not provide an effective surrogate 

for measuring population levels. We addressed the concerns raised by Cushman et 

al. (2007) by including variables, such as fine-scale habitat variables (e.g., snags, 

downed logs) and risk factors (e.g., roads, invasive species), in addition to cover 

type and structural stage in our evaluation of surrogate species viability. We evaluated our models using independent data on species distribution and abundance (for 

those species we could), and we included options for monitoring species populations and distribution for surrogate species with poor viability outcomes. We concur 

with Cushman et al. (2007) that monitoring habitat alone may not be an effective 

replacement for monitoring species population size and distribution.

We defined source habitats as those providing characteristics of macrovegetation that contribute to stationary or positive population growth (Wisdom et al. 

2000). Source habitats are distinguished from habitats simply associated with species occurrence; such habitats may or may not contribute to long-term population 

persistence (Wisdom et al. 2000). The macrohabitats used by each of the species 

considered in our assessment were described using cover type and structural stage. 

We included habitats used for reproduction, movement, and cover (e.g., protection, thermoregulation) as described by Johnson and O’Neil (2001), other primary 

literature, and professional judgment.

Vegetation for the east side of Washington was classified using a combination 

of cover types and structural classes (tables 1 and 2) similar to those described in 

Johnson and O’Neil (2001). Some of the Johnson and O’Neil (2001) cover types 

were combined to better match the vegetation classification used by the Forest Service. Also, a postfire cover type was included to identify vegetation that occurred 

immediately following stand-replacing fires. Six types of riparian habitat were also 

described.

The 26 classes of Johnson and O’Neil (2001) were condensed into 14 to reduce 

the types to a manageable list for our assessment (table 1). Two canopy closure 

breaks, open (equal to or less than 50 percent canopy closure) and closed (more 

than 50 percent) were used because they most effectively characterized the habitat 

relationships of wildlife species of conservation concern based on extensive review 

of the literature. Structural condition classes were described only for upland forested habitats (table 2).
7

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 1—Cover types used to describe source habitats and their relation to the Johnson and 

O’Neil (2001) habitat type classification

Cover type Habitat typesa

Open water Open water

Marsh Herbaceous wetlands

Wet meadow Herbaceous wetlands

Coniferous riparian Montane coniferous wetlands east-side (interior) riparian wetlands

Deciduous riparian/shrub wetland Montane coniferous wetlands east-side (interior) riparian wetlands

Alpine Alpine grassland and shrublands

Grasslands East-side (interior) grasslands

Shrublands East-side (interior) canyon shrublands shrub-steppe dwarf shrubsteppe desert playa and salt scrub shrublands

Juniper woodlands Western juniper and mountain mahogany woodlands

Montane mixed-conifer forest Montane mixed-conifer forest

East-side mixed-conifer forest East-side (interior) mixed-conifer forest

Lodgepole pine forest Lodgepole pine forest and woodlands

Ponderosa pine forest Ponderosa pine and east-side white oak forest and woodlands

Subalpine Subalpine parkland

a

 Source: Johnson and O’Neil 2001.
8

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 2—Structural stages used to describe source habitats and their relationship to the Johnson and 

O’Neil (2001) structural condition classes

Structure stage

Canopy 

covera Definition of structure stage Structural condition classes

Grass/forb Open Herbaceous seral stage in forested habitats Grass/forb–open 

Grass/forb–closed

Postfire Open First 10 years post-stand-replacing fire,

abundant standing dead trees

None

Sapling Open or

closed

Earlier seral stages in forested habitats from 

shrub stage through closed forest of trees 

<10 inches diameter at breast height (d.b.h.)

Shrub/seedling–open 

Shrub/seedling–closed 

Sapling/pole–open 

Sapling/pole–moderate 

Sapling/pole–closed

Small tree Open Primarily mid-seral stages 

May be later seral on harsher sites 

Forested stages with trees 10 to 15 in d.b.h.

Small tree–single story–open 

Small tree–single story–moderate 

Small tree–multistory–open 

Small tree–multistory–moderate

Small tree Closed Primarily mid-seral stages 

May be later seral on harsher sites Forested 

stages with trees 10- to 15 in d.b.h.

Small tree–single story–moderate 

Small tree–single story–closed 

Small tree–multistory–moderate 

Small tree–multistory–closed

Medium tree Open Usually mid- to late-seral stages 

Forested stages with trees 15 to 20 in d.b.h.

Medium tree–single story–open 

Medium tree–single story–moderate 

Medium tree-multistory–open 

Medium tree multistory–moderate

Medium tree Closed Usually mid- to late-seral stages 

Forested stages with trees 15 to 20 in d.b.h.

Medium tree–single story–moderate 

Medium tree–single story–closed 

Medium tree–multistory–moderate 

Medium tree–multistory–closed

Large tree Open Usually late-seral stages 

Forested stages with trees >20 in d.b.h.

Large tree–single story–open 

Large tree–single story–moderate 

Large tree–multistory–open 

Large tree–multistory–moderate 

Giant tree–multstory

Large tree Closed Usually late-seral stages 

Forested stages with trees >20 in d.b.h.

Large tree–single story–moderate 

Large tree–single story–closed 

Large tree–multistory–moderate 

Large tree–multistory–closed 

Giant tree–multistory

a

A break in canopy closure at 50 percent was used to separate open from closed canopy.
9

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Grouping Species of Conservation Concern

While managing species habitats and populations using a species-by-species 

approach has intuitive ecological merit, the sheer number of species of conservation 

concern often makes such an approach untenable. In many cases, the ecological 

understanding and resources needed to manage all species on an individual basis 

are not available. More importantly, attempting to manage for species of concern on 

an individual basis may not result in holistic management of the needs of all species because management focus is often fine scale, piecemeal, and without explicit 

understanding of the commonalities and differences in species needs among large 

sets of species (Wisdom et al. 2002).

Tremendous efficiencies are gained from managing groups of species. The 

idea that efficiency is gained while maintaining effectiveness in accounting for 

all species needs is a central premise to grouping approaches (Coppolillo et al. 

2008, Suring et al. 2011). Grouping species based on one or more ecological factors provides a strong foundation for developing conservation strategies for species 

of conservation concern because the conservation strategies are ordered around 

ecological principles. 

Species were grouped primarily based on habitat associations using cover type 

and structural stage (Suring et al. 2011, Wisdom et al. 2000). A cluster analysis was 

performed to describe groups of species based on their habitat associations. In the 

cluster analysis, 53 habitat variables were used consisting of six forest cover types, 

five tree size classes, and two canopy closure categories, three nonforest land cover 

types, six riparian/water land cover types, and a cave category. 

We sequentially examined sets of clusters, with increasing numbers of clusters 

in each set, to find an aggregation that was consistent with our understanding of 

species ecological relationships at the macrohabitat scale (as done by Wisdom et al. 

(2000). We also evaluated similarities among species and clusters using the Ochiai 

index of similarity (Ludwig and Reynolds 1988).

Based on our knowledge of ecological relationships of the species evaluated, 

we chose the smallest number of groups possible that still allowed a meaningful 

aggregation of species and habitats. Groups were then combined into families (categorical not phylogenetic) to help describe how similar groups of species are related 

to each other.2 Families include one or more groups that were associated with 

similar broad-scale macrohabitat conditions. These generalized habitat conditions 

2

 Note that the term “families” does not have a taxonomic meaning, but instead identifies 

robust similarities in habitat requirements among large groups of species, regardless of 

taxonomic relation (Wisdom et al. 2002).
10

GENERAL TECHNICAL REPORT PNW-GTR-907

were often used by managers to interpret broad-scale patterns and trends (Suring et 

al. 2011, Wisdom et al. 2000). By using a hierarchical evaluation of species, groups, 

and families, the analysis process addressed single and multispecies needs and 

identified patterns of habitat change similar to the process followed by Wisdom 

et al. (2000).

Identifying the Ecological Relationships of Species of 

Conservation Concern

We reviewed scientific information, in addition to defining source habitats, to more 

thoroughly understand the ecological requirements of the species of conservation 

concern. Additional information was compiled on risk factors, fine-scale habitat 

features, home-range size, and species ranges for each species of conservation 

concern. We followed the recommendations of Andelman et al. (2001) when determining what ecological information to compile for each species. Compiling this 

information was important for determining which species were best suited to be 

surrogate species, and to model relationships between species, habitats, and risk 

factors.

Risk Factors

Through literature review, we identified factors for species of conservation concern 

that potentially increased the risk of reducing (1) habitat availability, (2) habitat 

effectiveness (e.g., roads that reduce the probability of use of a habitat), and (3) 

population size and fitness (table 3).

The reviews by Wisdom et al. (2000), and Singleton and Lehmkuhl (1998) that 

addressed road-related factors, and Gaines et al. (2003a) that addressed recreationrelated factors were expanded to include risk factors associated with the management of vegetation, fire, grazing, and invasive species. 

Fine-Scale Habitats

In addition to broad-scale habitat relationships, we noted from Johnson and O’Neil 

(2001) whether a species used specific fine-scale habitats such as water features 

(e.g., springs and seeps), topographic features (e.g., talus slopes), within-stand 

features (e.g., logs, decayed trees), or other physical features (e.g., serpentine soil).

Home Range and Dispersal Information

Both the typical size of home range used by a species and the species’ dispersal 

capabilities influence which species best represent ecological requirements of other 

species (Coppolillo et al. 2008, Lambeck 1997, Noss et al. 1997). This information 

was compiled for all species of conservation concern.
11

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 3—Risk factors assessed for each surrogate species through literature reviews and used to develop 

surrogate species assessment models

Risk factor Effects of the risk factor

Hunting and trapping Mortality from hunting and trapping as facilitated by road and trail access

Poaching Increased illegal take of animals, as facilitated by road and trail access

Collisions Death or injury resulting from a motorized vehicle running over or hitting an animal 

as facilitated by road access

Negative human interactions Increased direct mortality of animals (e.g., shooting) as a result of increased contact 

with humans, as facilitated by road and trail access and increased building density

Movement barrier or filter Alteration of dispersal or other movements as a result of human activities (e.g., road 

or road networks, large openings from clearcuts, increased building density)

Displacement or avoidance Spatial shifts in animal populations or individuals away from human activities

Habitat loss and fragmentation Loss and fragmentation of source habitat resulting from human activities or fire 

Edge effects Changes to habitat associated with human-induced edges

Snag and downed log reduction Snag and downed log reduction associated with their removal along roads, trails, in 

timber harvest units, and during timber salvage operations

Collection Collection of live animals for use as pets (e.g., amphibians, reptiles), as facilitated by 

the physical characteristics of roads and trails or by road and trail access

Access for competitors or predators A physical human-induced change in the environment that provides access for competitors or predators that would not have existed otherwise (e.g., snow compaction 

by snowmobiles facilitates movements of coyotes and bobcats into lynx habitat)

Disturbance at a specific site Displacement of individual animals from a specific location that is being used for 

reproduction and rearing young

Snow compaction Direct mortality of animals crushed or suffocated as a result of snow compaction from 

snowmobile routes or groomed ski trails

Physiological response Increase in heart rate or level of stress hormones as a result of proximity to a human 

activity

Reduction of food or cover Reduction in the availability of food or cover as a result of human activities (e.g., 

cover reduction from forest thinning, forage reduction from domestic grazing)

Nest parasitism An increase in the potential for nest parasitism as a result of human activities (e.g., 

nest parasitism by cowbirds facilitated by proximity to agricultural lands)

Species Range Across the Assessment Area

Range information is helpful in determining which species may best represent the 

ecological requirements of other species across the assessment area (e.g., species 

with nonoverlapping ranges will poorly represent each others’ requirements). We 

define a species’ range as the polygon or polygons that encompass the outer boundaries of a species’ geographic occurrence within the assessment area. In addition 

to actual boundaries of species ranges, we categorized the extent of the species 

distribution within the assessment area as shown in table 4.
12

GENERAL TECHNICAL REPORT PNW-GTR-907

Selection of Surrogate Species

Wiens et al. (2008) summarized the pros and cons of using surrogate species 

as proxies for a broader set of species when the number of species of concern is 

too great to allow each species to be considered individually. In addition, they 

described the spatial scale at which a surrogate approach is likely most effective. 

They suggested that with small-size planning areas (hundreds of acres), the number 

of species may be small enough to allow individual species to be assessed, while 

for very large areas (regional or continental), surrogate species may not adequately 

represent the variety of taxa or habitats present. The area in-between was termed 

the surrogate zone where a surrogate-species approach might be most useful (Wiens 

et al. 2008). They also suggested that the most appropriate use of the surrogate 

approach would be when the management objective was to conserve or recover 

many species (e.g., >50) or when biological diversity conservation was broadly 

considered (Wiens et al. 2008). We met both of these criteria in that the size of our 

assessment area fell within the surrogate zone (intermediate between hundreds of 

acres and regional) and the management objectives were to address a broad array 

of species as required under the NFMA (about 200 species of conservation concern 

Table 4—Categories used to describe a species distribution within the 

assessment area

Distribution category Descriptions

Endemic Species whose entire distribution was restricted to the 

assessment area

Peripheral Species with only a small portion of their population that 

occurs within the assessment area

Inherently rare Species with low population numbers and not naturally 

well distributed across the assessment area

Large, interacting Broadly distributed species with one interacting population, the range is depicted as one large polygon that may 

encompass both used and unused areas

Large, disjunct Commonly occurring species with disjunct populations; 

range maps reflect the outer extent of individual populations; and the ranges consist of two or more separate 

polygons within the planning area, representing two or 

more separate populations that have limited interaction 

or do not interact

Small, isolated; and small, 

fragmented

Locally endemic species or species with small, scattered 

populations that can have ranges expressed as one small 

polygon (one small, isolated population), or a series of 

small populations (a set of small, fragmented populations)
13

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

in our case). Wiens et al. (2008) then went on to describe a process for selecting 

surrogate species, which we closely followed in our selection of a set of surrogate 

species. 

The surrogate species approach is an attempt to streamline the assessment of 

ecological systems by monitoring a subset of species. It is a pragmatic response to 

dealing with ecosystem complexity (Noon 2003, Roberge and Angelstam 2004) and 

is a rigorous way to deal with assessments that involve large numbers of species 

(Adelman et al. 2001, Roberge and Angelstam 2004). The key characteristic of a 

surrogate species is that status and trend of habitat conditions provide insights to 

the integrity of the larger ecological system to which it belongs (Andelman et al. 

2001, Lambeck 1997, Noon 2003, Noss et al. 1997). Surrogate species may serve as 

an umbrella function in terms of encompassing habitats needed for other species, 

being sensitive to the ecological changes likely to occur in the area, or otherwise 

serve as an indicator of ecological sustainability (Andelman et al. 2001, COS 1999, 

Lambeck et al. 1997, Noss et al. 1997, Wegner 2008). In addition, it is assumed that 

a surrogate species has more demanding requirements for factors putting other 

group members at greater risk of extinction than the rest of species in the group 

(Andelman et al. 2001). Surrogate species are intended to represent ecological 

conditions that provide for sustainable ecosystems, and it is not expected that the 

population dynamics of a surrogate species would necessarily represent the population dynamics of another species.

The concept of surrogate species differs from management indicator species 

(MIS) described in the regulations written to implement the NFMA (36 CFR 

219.19). The use of MIS was considered a means of evaluating the effects of management actions on a suite of species in that their population trends were assumed 

to reflect the changes in habitat amount and quality owing to the effects of the 

management actions (Suring et al. 2011). The MIS concept has been questioned in 

the literature over the past two decades (Andelman et al. 2001, Landres et al. 1988). 

The MIS concept evolved to the concept of surrogate species, in the late 1990s 

(Lambeck 1997). Surrogate species are considered a more appropriate approach to 

addressing species viability (Wiens et al. 2008).

Lindenmayer et al. (2002) pointed out some of the limitations of the surrogate 

species concept, including that the approach is data-intensive, that scientific understanding is lacking for many species, and were concerned that there is a lack of 

testing to validate the approach. Lindenmayer et al. (2002) suggest that the surrogate species approach not be the only approach used to guide landscape restoration. 

The surrogate species approach has recently been tested for wide-ranging carnivores (Carroll et al. 2001), birds (Drever et al. 2008, Watson et al. 2001), and fish 
14

GENERAL TECHNICAL REPORT PNW-GTR-907

(Wenger 2008). In addition, Roberge and Angelstam (2004) reviewed the umbrella 

species concept and concluded that the surrogate species approach seems the 

most promising because it provides a systematic procedure for selecting umbrella 

species. 

However, the risks and uncertainties involved in using the surrogate species 

concept must be recognized and acknowledged (Ficetola et al. 2007, Freudenberger 

and Brooker 2004). Development of a logical foundation for surrogate species selection is critical but poorly developed at this time (Noon 2003); however, advances 

have been made (see Freudenberger and Brooker 2004). In some cases, the use of 

surrogate species may fail to account for key requirements of individual species 

(Ficetola et al. 2005). This risk is highest when surrogate species identified through 

a process at a broad scale are then used in finer scale applications (Wisdom et al. 

2002).

The goal for our assessment was to have a manageable number of surrogate 

species (about 30) to assess while still maintaining a reliable inference for providing 

appropriate ecological conditions for nonsurrogate species. After species were clustered into groups based on habitat relationships and other environmental factors, a 

single or small set of surrogate species was identified within each group. The intent 

was to select a set of species that represented the full array of potential responses 

of species to management activities (Raphael et al. 2001). We used the following 

criteria to select surrogate species:

1. Represent source habitats: Species habitat use represents others in the 

group, and, in some cases, the family. If there were important differences in 

used source habitats among species within a group, multiple surrogate species were selected to represent the full array of source habitats used by the 

group. 

2. Risk factors: Species were selected that were affected by all or key combinations of risk factors identified for the group or family.

3. Fine-scale habitats: Species were selected to represent fine-scale habitat 

features identified for the group or family. For example, if some species 

within the habitat-based group used snags, then a species with the most 

demanding or limiting snag requirements was selected as a surrogate 

species.

4. Home range and dispersal information: We selected species with large 

home space-use requirements (Gaines et al. 2003b, Noss 1990). Knowledge 

of dispersal capabilities was lacking for most species, although, where 

possible, we selected species with the most limited dispersal capability as 

surrogate species.
15

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

5. Species range across the assessment area: Species with the widest distribution across the assessment area were given priority in the selection of surrogate species.

Four types of surrogate species were identified:

1. F indicated a surrogate species for the group that should be addressed in the 

development of management actions.

2. F* indicated that there was a choice of which surrogate species to use. 

Managers from different areas may choose different species primarily 

based on the distribution of the species.

3. f indicated species that had localized populations that were confined to 

very specific habitats. Proposed management alternatives for these species 

were applied only to local areas.

4. CS indicated a conservation strategy or recovery plan was in place, usually developed by the U.S. Fish and Wildlife Service under the Endangered 

Species Act. In some cases, the conservation strategy encompassed the 

range of other species in the group, and therefore other species in this group 

with similar source habitats and risk factors benefited from the conservation strategy.

Development of Surrogate Species Assessment Models

Assessing the viability of each surrogate species required the development of 

credible and repeatable analysis processes. This was accomplished through the 

use of Bayesian belief networks (BBNs) (Marcot et al. 2001, Raphael et al. 2001, 

Rieman et al. 2001). The use of Bayesian statistics, specifically BBNs, is one way 

to combine scientific data and information with expert knowledge and experience 

(Lehmkuhl et al. 2001; Marcot et al. 2001, 2006a, 2006b; Marcot 2006; Wade 2002; 

Wegner 2008). This is especially important when trying to assess multiple species, many of which have limited empirical data available. A BBN is an influence 

diagram that depicts the relationships among ecological factors (such as habitat 

and risks) that influence the likelihood of the outcome of some parameter(s) of 

interest, such as forest condition or wildlife species viability (Marcot et al. 2001). 

This approach provided a conceptual model outlining the interconnections among 

ecosystem components and how a species was anticipated to respond to risk factors. This represented an important step in the application of the surrogate species 

approach intended to provide insights into ecosystem processes and functions 

(Noon 2003, Ogden et al. 2003, Wegner 2008). 

We followed the guidelines suggested by Marcot et al. (2006a) to develop our 

surrogate species assessment models, which included the following steps: create 
16

GENERAL TECHNICAL REPORT PNW-GTR-907

an influence diagram of key factors affecting the viability of a species, develop an 

alpha-level BBN model from the influence diagram, revise the model with input 

from expert reviewers, test and calibrate the model with case files to create a betalevel model, and evaluate the model.

Surrogate species assessment models were used to assess response of surrogate 

species to changes in habitat conditions and risk factors resulting from proposed 

management actions. The BBN models provide a structured tool for integrating several sources of information to make comparisons among management alternatives 

on how well the conservation of surrogate species was addressed (Marcot et al. 

2001). The BBN modeling approach was selected for the following reasons (Marcot 

et al. 2001, Marcot 2006, Raphael et al. 2001):

1. Major influences on population persistence and/or quality of habitat is 

displayed.

2. Linkages between features of a proposed management action and the predicted response of a species are represented.

3. Empirical data and expert judgment are combined.

4. Models are easily rerun with different management actions or new model 

assumptions.

5. Predicted outcomes are based on probabilities and are presented as 

probabilities.

6. Model results included measures of uncertainty and sources of variation.

7. Model results are spatially explicit.

Surrogate species assessment models were developed for application at two spatial scales: the watershed (5th-field HUC) scale and the entire assessment area scale 

using information from each watershed. At the watershed scale, we developed the 

watershed index (WI), and a weighted watershed index (WWI). The WI provided 

a measure of change of source habitat (HRV compared to current conditions), and 

the influences of habitat quality (e.g., patch size) and risk factors (e.g., road density) 

for each watershed. The WWI was calculated from the WI by weighting it with the 

amount of source habitat that was currently available in each watershed. The WWI 

provided a measure of the capability of each watershed to contribute to the viability 

of the surrogate species. At the assessment area scale, we developed a viability outcome index (VOI) for each surrogate species. The VOI calculated an overall index 

of the potential capability of the assessment area to provide for the viability of the 

surrogate species. The VOI model used aggregated data from the watershed-scale 

models, and, for some species, an assessment of how well habitats are connected 

(how this was assessed is described later) across the assessment area.
17

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Once the surrogate species assessment modeling framework was established, 

a method for objectively assessing the quality and quantity of habitat available for 

surrogate species was chosen. We compared the current area of source habitat for 

a surrogate species within each watershed to estimate the HRV for that species’ 

source habitat (Lehmkuhl et al. 1997, Suring et al. 2011, Wisdom et al. 2000). The 

HRV refers to the composition, structure, and dynamics of ecosystems before 

Euro-American settlement (Fule ́ et al. 1997, Landres et al. 1999, Morgan et al. 

1994, Swanson et al. 1994). By comparing the current condition of source habitats 

with the HRV, insights were gained into the capability of each watershed to provide habitat that would contribute to the viability of surrogate species (Wisdom et 

al. 2000). We recognized that the HRV is likely to change as global and regional 

climates change (Gartner et al. 2008, Millar and Woolfenden 1999, Westerling et al. 

2006), which has implications for conservation of biological diversity (Lawler and 

Mathias 2007). However, we contend that understanding both the current condition 

and the HRV provide important information for managers to consider, along with 

climate change projections, in determining desired conditions for wildlife habitats 

(Wiens et al. 2012). Additionally, the HRV provides an objective measure of habitat 

sustainability and allows habitat restoration opportunities to be identified (Gaines 

2000, Society for Ecological Restoration 1993, Wisdom et al. 2000). We used published estimates for the HRV to develop reference conditions for surrogate species 

habitats (Agee 2003; Harrod et al. 1998; Hessburg et al. 1999b, 2000, 2005; Wright 

and Agee 2004).

The use of ecological thresholds is highly controversial and difficult to validate (Bestelmayer 2006, Lindenmayer and Luck 2005, Lindenmayer et al. 2006, 

Muradian 2001, Tear et al. 2005), yet they are continually being applied to address 

conservation issues (Groves 2003, Huggett 2005, Noss et al. 1997, Rompre et al. 

2010, Svancara et al. 2005, Tear et al. 2005). We conducted a review of the literature 

to identify a habitat threshold that we could apply to evaluate the number, distribution, and connectivity of watersheds across the assessment area in order to identify 

those watersheds that are in relatively good condition and may make important 

contributions toward the viability of surrogate species. We used the threshold to 

aid in priority setting for watershed restoration (e.g., Suding et al. 2004). Note that 

we did not use a threshold as a conservation goal; rather the threshold was used as 

a metric in the evaluation of species viability. We chose 40 percent as a minimum 

amount of source habitat after reviewing approaches used in other conservation 

assessments and empirical studies (Denoel and Ficetola 2007, Groves 2003, Noss et 

al. 1997, Olson et al. 2004, Radford et al. 2005, Rompre et al. 2010, Svancara et al. 

2005, Tear et al. 2005, Zuckerberg and Porter 2010). Svancara et al. (2005) showed 
18

GENERAL TECHNICAL REPORT PNW-GTR-907

that conserving a minimum of 40 percent of total available habitat maintained 

representation, resiliency, and redundancy in the remaining habitat and associated 

wildlife populations. Representation, resiliency, and redundancy were elements we 

considered important to maintaining or restoring species viability (Groves 2003, 

Shaffer and Stein 2000).

We developed surrogate species assessment models for each surrogate species 

using findings reported in the literature and from expert knowledge. The primary 

variables in the WI and WWI models included (1) reference conditions (e.g., estimates of HRV of source habitats), (2) estimates of the current amount and distribution of source habitats, (3) factors that influenced the quality of the source habitat 

(e.g., patch size, fine-scale habitat features, habitat connectivity), and (4) risk factors 

(e.g., road density, recreation routes, domestic grazing, invasive species). The 

approaches used to gather information to address the variables used in the surrogate 

species assessment models are described below. Details of the models developed for 

each surrogate species are provided in chapter 2.

Reference Conditions for Source Habitats

The current condition of source habitat within each watershed for a surrogate 

species was compared to reference conditions (e.g., HRV) for that species source 

habitat. The reference condition estimates within each watershed were based on the 

results of published analyses (table 5) (Agee 2003, Hann et al. 1997, Hessburg et al. 

1999a).

Table 5—Estimated reference conditions for forested habitats in the northeast Washington assessment 

areaa

Reference condition by structural stage group

Potential 

vegetation group Postfire

Early_

Open

Early_

All

Mid_ 

Open

Mid_ 

Closed

Late_

Mid_ 

Open

Late_

Mid_ 

Closed

Late_

Single_

Open

Late_

Single_

Closed

Late_

Multi_

Open

Late_

Multi_ 

Closed

Percent

Dry 10-18 10-22 10-25 18-32 5-8 18-32 5-8 11-31 2-5 1-8 0-1

Mesic 15-22 15-27 15-35 2-5 8-20 2-5 8-20 0-3 0-12 4-9 21-42

Cold-moist 10-14 10-20 10-36 1-4 9-27 1-4 9-27 0-1 0-5 3-7 23-59

Cold-dry 10-22 10-30 10-52 5-7 18-26 5-7 18-26 3-7 12-33 a Estimates of open/closed reference conditions were derived from table 3-3 in the Interagency Fire Regime Condition Class Guidebook V1.0.5.
19

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Reference Conditions of Forested Source Habitats

We estimated reference conditions for forested source habitats using the 

following steps:

Step 1. Using information in table 5, we identified the low and high percentages of 

forest group(s), structural stage(s), and canopy closure(s) that corresponded best to 

our description of source habitats for the surrogate species. 

Step 2. We then determined the area of each watershed that is potential source habitat based on the potential natural vegetation group (PVG). Potential source habitat 

was a combination of PVGs that had the capability of providing source habitat given 

the appropriate structure stage and canopy closure were present. 

Step 3. We used the percentages derived from step 1 and the area estimates from 

step 2 to calculate a range of high and low area estimates of the predicted amount of 

source habitat for each watershed. 

Step 4. We then divided the range of area estimates from step 3 by the area (size) 

of each watershed that corresponded to the appropriate PVG to get estimates of the 

percentage of each watershed that historically had the potential to provide source 

habitat for the surrogate species. Each watershed had a high and low percentage generated at this step. We used the absolute low and absolute high across all 

watersheds to bound our estimated reference condition for each species. We also 

calculated the median percentage of the potential of all the watersheds. 

Step 5. We then classified the range into four equal categories between the absolute 

low and the median, and four equal categories between the median and the absolute 

high (fig. 2).

Reference Conditions of Postfire Source Habitats

Reference conditions for postfire source habitats were derived from the information presented in table 6; the proportion of the landscape that was in an early-seral 

reference condition for each forest type. Forest and fire ecologists were asked to 

estimate how much of the early-seral reference condition would be in a <10 years 

postfire condition. Ten years was derived from descriptions of postfire habitat use 

Figure 2—Departure classes were created using low, median, and high projected estimates of the amount of source 

habitat for each watershed.
20

GENERAL TECHNICAL REPORT PNW-GTR-907

by woodpeckers (Lehmkuhl et al. 2003, Saab and Dudley 1998) and postfire snag 

fall rates (Everett et al. 1999, Harrod et al. 1998).

Reference Conditions for Species Associated With Nonforested 

Source Habitats

As described above, in forested communities we have estimated proportions of 

different PVGs and structural stages that were likely to occur at any given time 

considering succession and disturbance across the landscape. In the nonforested 

shrublands and riparian environments, we did not have published estimates of HRV 

to use as reference conditions. Therefore, to evaluate the relative amount of upland 

nonforest source habitat within watersheds, we assumed that land currently occupied by agriculture and urban areas within the assessment area historically supported shrub-steppe, grasslands, or wet meadows. The proportions of shrub-steppe, 

grasslands, and wet meadows cover types in the existing mapped shrub-steppe 

vegetation zone were multiplied by the area currently in agriculture and urban 

areas, and the result added to the area currently in these cover types to obtain an 

estimate of the reference conditions of source habitat for surrogate species (table 7). 

Historical grasslands = {[current grass/ (current grass + current shrub)] X 

(urban + agriculture)} + current grass

Historical shrub = {[current shrub/ (current shrub + current grass)] X (urban + 

agriculture)} + current shrub

We then created nine classes of departure to measure the relative amount of 

source habitat within each watershed: 16 to 30 percent below the median = -1; 

31 to 45 percent below the median = -2; 46 to 60 percent below the median = -3; 

>60 percent below the median = -4; 16 to 30 percent above the median = +1; 31 to 

45 percent above the median = +2; 46 to 60 percent above the median = +3; >60 

percent above the median = +4; 0 to 15 percent above or below the median = 0 

departure.

Table 6—Estimated reference conditions for 

postfire habitats by forest group in the northeast 

Washington assessment area

Forest group

Percentage of forested landscape 

in postfire source habitat

(<10 years postfire)

Dry 10 to 18

Mesic 15 to 22

Cold-moist 10 to 14

Cold-dry 10 to 22
21

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 7—An example of estimates of the relative amount of upland nonforest 

source habitat within two watersheds

Huc5 name

Current 

urban_

agri._

Habitats 

current 

grassland_

Current 

shrubsteppe_Current 

total

Historical 

grass 

Historical 

shrub 

American River 0 140 0 140 140 0

Boulder/Deadman 110 3,665 10,565 14,339 3,693 10,646

Huc5 = hydrological unit code level 5.

Reference Conditions for Wetland and Riparian Source Habitats

Numerous reports describe how human activities (e.g., those associated with dams, 

diversions, agriculture conversion, stream channelization, road construction, 

etc.) have permanently altered large areas of wetland habitat. Brinson et al. (1981) 

estimated that 9.3 million ha (3.2 million ac) of the original flood-plain forest 

was converted to urban and cultivated agricultural land uses in the United States. 

Klopatek et al. (1979) estimated that northern floodplain forests have decreased 69 

percent in area from their potential, and Hirsh and Segelquist (1978) estimated that 

70 to 90 percent of all natural riparian areas was subjected to extensive alteration. 

Little is known about the extent and status of mountain riparian ecosystems, which 

are affected primarily by impacts associated with other natural resource uses (e.g., 

timber harvest, recreation, livestock grazing) although federal and state surveys 

have found that 50 percent of all fish habitats on public and private lands in western 

Oregon have been altered since 1960 (Kadera 1987). Dahl (1990) described that 

about 47.3 million ha (11.6 million ac) or 53 percent of all U.S. wetlands have been 

lost since the 1780s. Based on these studies, we assumed that the current amount of 

source habitat for wetland and riparian deciduous surrogate species in the assessment area was about 70 percent of the historical amount in each watershed (Dahl 

1990, Peters 1990). In the WI source habitat departure node, we used the [(-1) – (-2)] 

category for every watershed to reflect our assumption that the availability of these 

habitats was near 70 percent of their historical median.

Reference Conditions for Streamside Riparian and Cliff Source 

Habitats

For these habitats, we assumed that their availability has not changed from their 

historical amounts. Therefore, our assessment focused on factors that could influence the quality of these habitats. In the WI source habitat departure node, we used 

the 0 to 1 quartile for every watershed to reflect our assumption that the availability 

of these habitats was near the historical median.
22

GENERAL TECHNICAL REPORT PNW-GTR-907

In summary, we used the following approach to standardize how we estimated 

habitat departure for each surrogate species (table 8).

Step 1. We identified combinations of spatial data that best represented the source 

habitat for the surrogate species.

Step 2. We determined the amount of source habitat within each watershed that was 

located within the assessment area through geographic information system (GIS) 

processes. 

Step 3. We compared the current estimates of source habitat to our estimates for 

the reference conditions for each watershed and determined the degree of departure 

based on table 8. For example, if 1,000 ac of source habitat occurred in the watershed and that value falls between 2 and 3 categories below the median (-3Q to -2Q), 

a likelihood of 100 percent is entered in the -3 to -2 category reference condition 

node (see example below). 

If there currently is no source habitat in the watershed and source habitat did 

not occur in the watershed historically, then we entered zero in the habitat potential 

node that resulted in a 100 percent likelihood of zero habitat in the habitat amount 

versus reference condition node.

Factors That Influenced Habitat Quality

Several factors were identified from our literature review that influence habitat 

quality for the surrogate species source habitats and were incorporated into the 

surrogate species assessment models. 

Patch size— 

We used the average patch size of source habitat in each watershed to assess the 

current condition for those species that might be affected by patch size.

Snags— 

Snags were an important component of source habitat or were important determinants of habitat quality for a number of surrogate species. (Mellen-McLean et al. 

2009, Rose et al. 2001). We used information from Ohman and Gregory (2002) to 

estimate the current density of snag habitat, overlayed this with our source habitat 

data, and then summarized the availability of snag habitat within source habitat 

for each watershed. Ohman and Gregory (2002) used snag data from the Forest 

Inventory and Analysis (FIA) plots and a gradient nearest neighbor (GNN) analysis 

to estimate the density of snags. These data are not accurate at small spatial scales 

(Ohman and Gregory 2002), which is why we chose to summarize the snag information for all source habitat within a watershed.
23

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 9—Historical reference condition classes for snags by surrogate species

Surrogate species Forest type Snag size Low Moderate High

Very 

high

D.b.h. - - - - - - - - - - - Per hectare - - - - - - - - - - -

Lewis’s woodpeckera Dry >50 cm <2.47 2.47 to -<3.1 3.1 to 3.7 >3.7

White-headed woodpeckera Dry >50 cm <2.47 2.47 to 3.1 3.1 to 3.7 >3.7

Western bluebirda Dry >37.5 cm <5.19 5.19 to <6.9 6.9 to <8.65 >8.65

Black-backed woodpeckerb Dry, mesic 

Cool-moist, 

Cold-dry

>25 cm <9.13 9.13 to 17.9 18.0 to 45.0 >45.0

Pileated woodpeckerb Mesic, dry >50 cm <1 1.1 to 3.6 >3.6 to 39.3 >39.3

Fringed myotisb Mesic, dry >50 cm <1 1.1 to 3.6 >3.6 to 39.3 >39.3

D.b.h. = diameter at breast height.

a Based on Harrod et al. 1998.

b Based on Mellen-McLean et al. 2009.

We developed reference conditions for snag densities for surrogate species 

using information from Harrod et al. (1998) for the dry forests. We used the tolerance levels from Mellen-McLean et al. (2009) for snag density from unharvested 

inventory plot data (including plots with no snags) for east-side mixed-conifer 

(EMC-NCR), large tree vegetation type for pileated woodpecker and fringed 

myotis, averaged snag densities at the three tolerance levels across EMC-NCR, 

ponderosa pine/Douglas-fir (PPDF), and montane mixed-conifer (MMC), smallmedium tree vegetation types for black-backed woodpecker (table 9). 

We compared the watershed mean snag density estimates to the reference 

conditions to determine the current condition scores for snag habitat (low, moderate, high, very high) (table 9) for each watershed.

Table 8—Summary of how habitat departure was evaluated for each habitat group

Departure category

Habitat group -4 -3 -2 -1 0 1 2 3 4

Forested Absolute 

low

Median Absolute 

high

Nonforested RC .4 RC .55 RC .70 RC .85 RC median

Wetlands RC 4 RC .55 RC .70++ RC .85 RC median

Stream riparian RC = current

RC = reference conditions.
24

GENERAL TECHNICAL REPORT PNW-GTR-907

Late-successional forest— 

Several surrogate species were associated with late-successional forests or structural attributes associated with late-successional forest (e.g., large trees, down wood, 

etc.). We used a combination of forest cover types, medium and, large tree size 

classes (>15 in quadratic mean diameter [QMD]), and canopy closure (>70 percent 

canopy closure) to define late-successional forests.

Denning— 

For many species, denning habitat comprised fine-scale habitat features beyond 

our ability to spatially evaluate. However, potential wolverine denning habitat was 

mapped using land-type associations (USDA FS 2000) that correspond to alpine 

cirques with the type of structure typically used by wolverines for natal dens 

(Copeland 1996) and are likely to have adequate snow cover also important for denning (Copeland 2010). These included land type associations Ha7, Ha8, Hb9, and 

Hi9 (USDA FS 2000).

In addition, down woody debris is an important component of lynx denning 

habitat (Koehler 1990, Mowat et al. 2000, Organ et al. 2008, Squires and Laurion 

2000). We could not specifically identify lynx denning habitat, but we used the 

availability of down woody debris as a way of assessing the quality of the source 

habitat and its potential to provide this component of lynx denning habitat. The 

down wood density values calculated from the FIA data through the GNN analysis 

(Ohman and Gregory 2002) were used to quantify the availability of down wood 

within source habitat for lynx and summarized for each watershed.

Open landscape— 

We used all vegetation types with less than 10 percent tree canopy closure to identify portions of the landscape that were considered open. This variable was used to 

evaluate habitat for each watershed for species that require relatively high levels of 

forest cover.

Shrub cover— 

For species that are affected by the amount of shrub cover, such as the fox sparrow, 

we used the GNN data from Ohmann and Gregory (2002) to identify the percentage 

of shrub cover in source habitat for each watershed.

Cliffs— 

Cliffs provided important habitat features for several surrogate species and 

were identified using a digital elevation model. We found that a slope break of

38 degrees identified most of the cliff structures used by the surrogate species we 

were assessing. 
25

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Riparian and wetland habitats— 

In addition to providing source habitat for some of the surrogate species, riparian 

and wetland habitats were also an important determinant of habitat quality for other 

species. Therefore, we mapped riparian and wetland habitats using the national 

wetlands inventory.

Risk Factors

We conducted a literature review to identify the risks that most likely influenced 

surrogate species persistence and to develop indices (e.g., road density, zone of 

influence) that could be used to spatially evaluate levels of risk. Application of 

these indices relied on the availability of spatial data describing factors such as 

roads, trails, and human population centers. 

Recreation routes and sites— 

Recreation routes such as roads, trails, snowmobile routes, and groomed ski trails 

were identified as risk factors for a number of surrogate species. We summarized 

road and trail densities from current maps into the following categories: no roads, 

<1 m/m2

, 1 to 2 m/m2, and >2 m/m2 (based on Gaines et al. 2003, Wisdom et al. 

2000). For several surrogate species, we used proximity of source habitat to roads 

and trails (also referred to as zone of influence) to evaluate the effects of disturbance on surrogate species. Distance buffers placed on roads and trails to evaluate 

proximity were based on the literature review of Gaines et al. (2003). We also used 

locations and densities of recreation sites, such as campgrounds and boat launches, 

when literature showed these features were important risk factors for surrogate 

species.

Domestic grazing— 

Grazing by domestic livestock was evaluated as a risk factor for several surrogate 

species. This was determined by overlaying the location of active grazing allotments on maps of source habitat. Only currently active allotments were used to 

assess risks to surrogate species. We were not able to evaluate the intensity of the 

grazing that occurred within the grazing allotments as this information was not 

available spatially.

Invasive species— 

Stocking of nonnative fish species was identified as a risk factor for some surrogate 

species. This practice occurs throughout the assessment area and was documented for each water body by gathering stocking information from the Washington 

Department of Fish and Wildlife.
26

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 3—Viability outcome Bayesian belief network model for the northeast Washington assessment area. WWI = 

weighted watershed index, Huc = hydraulic unit code.

Housing density— 

We obtained spatial information on housing density to index the effects of human 

development on surrogate species source habitats and habitat effectiveness.

Viability Outcomes

The VOI model was developed for each surrogate species to incorporate information from the WI scores; distribution of source habitats across the assessment area; 

and for some species, how well habitats were connected across watersheds (fig. 3, 

table 10). The VOI is a large-scale index of population abundance and distribution 

(based on habitat and risk factors) across the landscape, not an actual prediction 

of population occurrence, size, density, or other demographic characteristics. 

We assumed that species with high VOI scores have a high probability of having 

populations that are self-sustaining and well distributed throughout their historical 

ranges in the assessment area.

The VOI model incorporated the WWI score (described earlier); a habitat distribution index; and for some species, a habitat connectivity index that assessed how 

well habitats were connected across watersheds. Each variable of the VOI model is 

described in detail below.
27

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 10—Key indices used in the surrogate species assessment models and 

viability outcome model

Index Definition

Watershed index (WI) A measure of amount (reference condition vs. current) of 

source habitat, and the influence of habitat quality and risk 

factors for each watershed in the assessment area. Provides 

an index of the capability of the watershed to contribute to 

the viability of the surrogate species.

Weighted watershed index 

(WWI)

The WI weighted by the amount of source habitat in the watershed. Provides a relative measure of the potential capability 

of the watershed to contribute to the viability of the surrogate 

species.

Current WWI: historical 

WWI

Provides a measure of the current capability of the assessment 

area to contribute to the viability of the surrogate species 

compared to the historical capability.

Dispersal habitat suitabilityCalculated for Canada lynx, American marten, bighorn sheep, 

and wolverine. Provides a measure of the relative permeability of the landscape considering habitat characteristics 

(e.g., cover type, vegetation structure) and risk factors (e.g., 

road density, housing density) during current and historical 

conditions.

Ecoregionsa

 with watersheds greater than minimum habitat amount

This node was calculated for each surrogate species to assess 

the distribution of watersheds with current source habitat 

amounts that were >40 percent of the historical median of 

source habitat. We used the estimates of the reference conditions of source habitat to calculate the median amount of 

source habitat across all watersheds that occurred within the 

distribution of the surrogate species in the assessment area. 

We then determined the number of ecoregions that contained 

>1 watershed that exceed the habitat minimum.

Percentage of watersheds 

greater than minimum 

habitat amount

An assessment of the proportion of watersheds with current 

source habitat amounts that were >40 percent of the median 

reference condition of source habitat. We used the estimates 

of the reference conditions of source habitat to calculate the 

median amount of source habitat across all watersheds that 

occurred within the distribution of the surrogate species in 

the assessment area.

Viability outcome index An index of how well the assessment area contributes to the 

viability of the surrogate species.

a

 Ecoregions were paired 4th-field subbasins that were identified by vegetation ecologists to create relatively 

similar land units for vegetation modeling.
28

GENERAL TECHNICAL REPORT PNW-GTR-907

Weighted Watershed Index Calculation

The WWI was incorporated into the VOI model by calculating the ratio of current 

WWI to historical WWI to assess the current capability of the assessment area to 

provide for the viability of surrogate species. The WWI score was calculated using 

the following method (table 11):

Step 1. We determined the current WIs for each watershed in the assessment area 

through application of the surrogate species assessment models.

Step 2. We determined the historical WIs for each watershed in the assessment 

area by setting all human influence nodes to zero, assuming the amount of source 

habitat is one category above the reference condition median, and assuming the 

snag variable (for those species that have it) was at the 50 to 80 percent tolerance 

level (Mellen-McLean et al. 2009) (table 11).

Step 3. We weighted the current and historical WIs using the current amount and 

historical estimates of source habitat within each watershed.

Step 4. We then summed the current (W) and historical (X) amount of source 

habitat across all watersheds and divided the sum of the weighted WI values for all 

watersheds by this number. This resulted in an overall weighted WI value for both 

current (Y/W) and (Z/X) historical conditions (table 11).

Step 5. We determined the ratio of the current WWI:historical WWI to determine 

the relationship between current and historical conditions for each surrogate species 

in the assessment area.

Table 11—Hypothetical example showing the calculations for the overall weighted 

watershed index (WI) value

WI score 

current

WI score 

historical

Source 

habitat 

current

Source 

habitat 

historical

Weighted 

WI score 

current

Weighted 

WI score 

historical

- - - - - Acres - - - - -

Watershed A 1.3 3.0 50 80 65 240

Watershed B 2.1 3.0 70 75 147 225

Watershed C 2.7 3.0 90 95 243 285

Totals W = 210 X = 250 Y = 455 Z = 750

Overall weighted WIs Y/W = 2.17 Z/X = 3.0

Current: historical 2.17/3.0 = 0.72
29

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Habitat Distribution Index

This index assessed how watersheds with relatively high amounts of source habitat 

were distributed across the assessment area. The habitat distribution index was calculated by the interaction of two variables: number of ecoregions (see footnote 3)

with at least one watershed that met a threshold for the amount of source habitat, 

and percentage of the total number of watersheds that met the threshold for amount 

of source habitat. The threshold amount of source habitat within a watershed was 

at least 40 percent of the historical median of source habitat (see page 17 for further 

explanation).

We estimated the habitat distribution index for historical conditions as well. We 

did this by determining which of the watersheds had historical estimates of source 

habitat amounts that were >40 percent of the median of the historical amount across 

all watersheds, and then used those watersheds to calculate the number of ecoregions with at least one watershed above the 40 percent threshold, and percentage of 

watersheds with source habitat above the 40 percent threshold.

We categorized the habitat distribution index for both current and historical conditions as follows: low habitat distribution equals less than or equal to 

one ecoregion with at least one watershed above the 40 percent source habitat 

threshold; moderate = two to three ecoregions with at least one watershed above 

the 40 percent source habitat threshold; and high = four to five ecoregions with at 

least one watershed above the 40 percent source habitat threshold. We categorized 

the percentage of watersheds within the assessment area that met the 40 percent 

threshold habitat amounts under both current and historical conditions into 10 equal 

categories from 0 to 100 percent (10 percent increments) (see fig. 3).

Dispersal Habitat Suitability

We evaluated dispersal habitat suitability for surrogate species whose dispersal 

patterns were appropriate to assess at the spatial scale of our assessment area. Our 

analysis was based on the idea that resistance to movement across a landscape can 

be mapped by assigning resistance values to habitat attributes. These values depict 

the relative “cost” for an animal to move across areas (Singleton et al. 2002, WWHCWG 2010). Areas with “good” habitat characteristics (i.e., forested land cover, low 

road densities, and low human population densities) have low costs of movement, 

whereas areas with “poor” habitat characteristics (i.e., agriculture land cover, high 

road densities, and high human population densities) have high movement costs. 

The criteria used to determine which species to evaluate included (1) moderate 

to large (>2,471-ac) home range size, (2) relatively large dispersal distances (>6.2 
30

GENERAL TECHNICAL REPORT PNW-GTR-907

mi), (3) knowledge of potential dispersal barriers, and (4) dispersal limited (e.g., 

many surrogate bird species were not dispersal limited) and habitat limited (not a 

habitat generalist).

Canada lynx, wolverine, bighorn sheep, and American marten were identified 

as appropriate species to evaluate. Methods similar to those used by Singleton et al. 

(2002) and WHCWG (2010) were used to model dispersal habitat suitability within 

the assessment area. 

We compiled datasets of land cover types, canopy closure, vegetation zones, 

road density, motorized and nonmotorized trail density, human population density, 

slope, and elevation. These attributes were assigned resistance values ranging from 

0.1 (high cost of movement) to 1, (low cost of movement) based on extensive literature review and expert knowledge (table 12). All datasets for each surrogate species 

assessed were combined using math algebra resulting in an overall score between 

0 (low permeability) and 1 (high permeability). This analysis resulted in a map that 

depicts the cumulative energetic cost for an animal to move across the landscape, 

expressed as “dispersal habitat suitability.” The relative importance of each parameter was reflected in the permeability value it was assigned. Parameters with more 

influence were attributed with coefficients of lower values and a higher range of 

scores (i.e., 0.1 to 1) than parameters with less influence (i.e., 0.6 to 1). The overall 

permeability score was determined by calculating the percentage of the assessment 

area in three dispersal habitat suitability classes (high = >0.5, moderate = 0.1 to 0.5, 

and low = 0.0 to 0.1). All spatial analysis was done using ArcInfo 9.0 (ESRI 2004) 

in a Windows NT environment.

We evaluated historical dispersal habitat suitability by “turning off” the effects 

of roads and trails, and housing density variables. We did not attempt to evaluate 

the influences of changes in the vegetation-related variables (vegetation zone, cover 

type, canopy cover) between current and historical conditions as we did not have 

information on the spatial distribution of historical vegetation available.

Viability Outcomes for Surrogate Species

Environmental outcomes defined in Raphael et al. (2001) were used as a basis to 

describe five viability outcomes. These outcomes were calculated for current and 

historical conditions for each surrogate species to assess changes in habitat conditions. The term “suitable environment” refers to a combination of source habitat 

and risk factors that influence the probability of occupancy and demographic 

performance of a surrogate species. The viability outcomes are based on departure 

from historical conditions. The five viability outcomes we used were:
31

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 12—Habitat variables and resistance values used to

evaluate dispersal habitat suitability for American marten, 

bighorn sheep, Canada lynx, and wolverine within the northeast 

Washington assessment area (continued)

Resistance values for surrogate species

Habitat variable

American 

marten

Bighorn 

sheep

Canada 

lynx Wolverine

Vegetation zone

Alpine 0.1 0.1 0.8 1.0

Parkland 0.3 0.1 0.9 1.0

Subalpine fir 1.0 0.1 1.0 1.0

Mountain hemlock 1.0 0.1 1.0 1.0

Pacific silver fir 1.0 0.1 0.8 1.0

Western hemlock 1.0 0.1 0.8 1.0

Grand fir 1.0 0.1 0.7 0.8

Douglas-fir 0.7 1.0 0.7 0.8

Oregon white oak 0.3 0.1 0.6 0.5

Ponderosa pine 0.5 1.0 0.6 0.8

Shrub steppe 0.1 1.0 0.5 0.5

Cover type

Mixed conifer 0.7 0.8 1.0

Douglas-fir 0.7 0.7 1.0

Engelmann spruce 1.0 0.8 1.0

Grand fir 1.0 0.7 1.0

Lodgepole pine 0.7 1.0 1.0

Mountain hemlock 1.0 1.0 1.0

Pacific silver fir 1.0 0.8 1.0

Parkland 0.5 0.9 1.0

Subalpine fir 1.0 1.0 1.0

Western hemlock 1.0 0.8 1.0

Western larch 0.7 0.7 1.0

Western redcedar 1.0 0.8 1.0

Meadow 0.1 0.8 0.8

Nonvegetated 0.0 0.7 0.8

Ponderosa pine 0.4 0.6 0.8

Riparian deciduous 0.6 0.9 0.8

Wet meadow 0.1 0.8 0.8

Dry meadow 0.1 0.6 0.6

Grassland 0.1 0.5 0.5

Shrub 0.2 0.5 0.5
32

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 12—Habitat variables and resistance values used to

evaluate dispersal habitat suitability for American marten, 

bighorn sheep, Canada lynx, and wolverine within the northeast 

Washington assessment area (continued)

Resistance values for surrogate species

Habitat variable

American 

marten

Bighorn 

sheep

Canada 

lynx Wolverine

Shrub steppe 0.1 0.5 0.5

Oregon white oak 0.5 0.5 0.5

Urban/agriculture 0.0 0.1 0.1

Water 0.0 0.1 0.1 0.1

Ponds/lakes 0.0 0.1 0.1 0.1

Roads and motorized trail density

(km/km2

)

0 to 0.1 1.0 1.0 1.0 1.0

0.1 to 1.6 0.8 1.0 1.0 1.0

1.6 to 3.2 0.6 0.8 1.0 0.8

3.2 to 6.4 0.5 0.6 1.0 0.6

6.4 to 9.7 0.4 0.5 0.8 0.5

9.7 to 12.9 0.3 0.4 0.7 0.4

12.9 to 16.1 0.2 0.2 0.3 0.2

>16.1 0.1 0.1 0.1 0.1

Nonmotorized trail buffer

Meters

<200 0.6

>200 1.0

Housing density 

Ac/unit

0 or no data 1.0 1.0 1.0 1.0

>80 1.0 1.0 1.0 1.0

50 to 80 1.0 0.8 1.0 0.8

40 to 50 0.8 0.6 0.8 0.6

30 to 40 0.7 0.6 0.7 0.6

20 to 30 0.5 0.4 0.5 0.4

10 to 20 0.3 0.2 0.3 0.2

1.7 to 10 0.2 0.1 0.2 0.1

0.6 to 1.7 0.1 0.1 0.1 0.1

<0.6 0.1 0.1 0.1 0.1
33

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

1. Outcome A—Suitable environments are broadly distributed across the historical range of the species throughout the assessment area. Habitat abundance is high relative to historical conditions. The combination of distribution 

and abundance of environmental conditions provides opportunity for continuous or nearly continuous intraspecific interactions for the surrogate species.

2. Outcome B—Suitable environments are broadly distributed across the historical range of the species. Suitable environments are of moderate to high 

abundance relative to historical conditions, but there may be gaps where 

suitable environments are absent or present in low abundance. However, 

any disjunct areas of suitable environments are typically large enough and 

close enough to permit dispersal among subpopulations and to allow the 

species to potentially interact as a metapopulation. Species with this outcome are likely well distributed throughout most of the assessment area.

Table 12—Habitat variables and resistance values used to

evaluate dispersal habitat suitability for American marten, 

bighorn sheep, Canada lynx, and wolverine within the northeast 

Washington assessment area (continued)

Resistance values for surrogate species

Habitat variable

American 

marten

Bighorn 

sheep

Canada 

lynx Wolverine

Elevation 

Meters

0 to 1000 0.8 0.8 0.6

1000 to 1500 1.0 1.0 0.8

>1500 1.0 1.0 1.0

Slope (degrees)

0 to 20 1.0 1.0 1.0

0 to 31 0.4

20 to 40 0.8 0.8 0.8

31 to 38 1.0

>40 0.6 0.6 0.6

>38 0.6

Canopy cover (percent)

Percent

0 to 40 1.0

40 to 60 0.6

>60 0.1
34

GENERAL TECHNICAL REPORT PNW-GTR-907

3. Outcome C—Suitable environments moderately distributed across the historical range of the species. Suitable enviroments exist at moderate abundance relative to historical conditions. Gaps where suitable environments 

are either absent or present in low abundance are large enough such that 

some subpopulations may be isolated, limiting opportunity for intraspecific 

interactions especially for species with limited dispersal ability. For species for which this is not the historical condition, reduction in the species’ 

range in the assessment area may have resulted. Surrogate species with this 

outcome are likely well distributed in only a portion of the assessment area.

4. Outcome D—Suitable environments are low to moderately distributed 

across the historical range of the species. Suitable environments exist at low 

abundance relative to their historical conditions. While some of the subpopulations associated with these environments may be self-sustaining, there is 

limited opportunity for population interactions among many of the suitable 

environmental patches for species with limited dispersal ability. For species 

for which this is not the historical condition, reduction in species’ range in 

the assessment area may have resulted. These species may not be well distributed across the assessment area.

5. Outcome E—Suitable environments are highly isolated and exist at very 

low abundance relative to historical conditions. Suitable environments are 

not well distributed across the historical range of the species. For species 

with limited dispersal ability there may be little or no possibility of population interactions among suitable environmental patches, resulting in 

potential for extirpations within many of the patches, and little likelihood of 

recolonization of such patches. There has likely been a reduction in the species’ range from historical conditions, except for some rare, local endemics that may have persisted in this condition since the historical period. 

Surrogate species with this outcome are not well distributed throughout 

much of the assessment area.

Habitat Conditions for Conservation Planning

For each surrogate species, we classified each watershed into one of five habitat 

conditions (table 13). The habitat conditions were based on the WI scores and 

whether the current amount of source habitat was above or below 40 percent of 

the historical median. This allowed the identification of a basic set of management 

options to consider:
35

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 13—Definitions for habitat conditions (HC) and their primary management options

Habitat condition Definition Potential management options to consider

Habitat condition 1a, 1b The quality and quantity of source habitat is 

relatively unchanged from historical conditions. Watershed index >2.0 and the amount 

of source habitat is (a) >40 percent of the 

historical median or (b) <40 percent of the 

historical median.

Protection of existing source habitat, 

especially in habitat condition 1a. 

Restoration can occur elsewhere as needed.

Habitat condition 2a, 2b The quality and quantity of source habitat has 

been moderately reduced (WI 1.0 to 2.0), and 

the amount of potential source habitat is (a) 

>40 percent of the historical median or (b) 

<40 percent of the historical median.

Restoration of source habitats. 

Protection of existing source habitat 

Restoration of habitat condition 2a.

Habitat condition 3a, 3b The quality and quantity of source habitat has 

been severely reduced (WI <1.0) and the 

amount of potential source habitat is (a) >40 

percent of the historical median or (b) <40 

percent of the historical median.

A combination of protection and restoration 

depending on the juxtaposition of these 

watersheds in relation to HC1 and HC2 

watersheds.

Habitat condition 4 Connectivity or habitat distribution indices 

identify significant gaps in the distribution of 

watersheds with >40 percent of the historical 

median of source habitats.

Manage for dispersal habitat that provides 

for habitat connectivity.

Habitat condition 5 The amount of source habitat in the watershed 

for the surrogate species <25 percent on 

federal ownership.

Land ownership limits the strategies that can 

be used to contribute to species viability.

• Habitat condition 1—Protection of habitat in watersheds that were in good 

condition

• Habitat condition 2—Restoration of habitat within watersheds that were in 

moderate condition but could be raised to a habitat condition 1 with a reasonable amount of effort

• Habitat condition 3—Watersheds have been severely degraded and may 

require substantial commitment of resources to improve the condition

• Habitat condition 4—Watersheds that were important for connectivity 

owing to their location

• Habitat condition 5—Watersheds with limited federal land ownership 

Overall Results of the Surrogate Species Assessments

We evaluated more than 700 species (67 percent birds, 23 percent mammals, 5 percent amphibians, 5 percent reptiles) documented to occur in the Pacific Northwest 

Region (Oregon and Washington) (Suring et al. 2011). Following the application 

We evaluated more 

than 700 species (67 

percent birds, 23 

percent mammals, 5 

percent amphibians, 

5 percent reptiles) 

documented to occur in 

the Pacific Northwest 

Region (Oregon and 

Washington).
36

GENERAL TECHNICAL REPORT PNW-GTR-907

of the screening criteria, we identified 209 species of conservation concern on 

National Forest System lands east of the crest of the Cascade Range. We aggregated these species into 10 habitat families and 28 habitat groups based on habitat 

associations. We identified 52 surrogate species for the national forests east of the 

Cascades Range in Oregon and Washington (Suring et al. 2011), which included 67 

percent birds, 17 percent mammals, 14 percent amphibians, and 2 percent reptiles 

based on risk factors and ecological characteristics. We selected 32 of the surrogate 

species for evaluation in the northeastern Washington assessment area. The species identified as species of conservation concern are shown in appendix 2. These 

species represent the full range of habitats and risk factors.

We developed surrogate species assessment models for 27 of the 32 surrogate 

species used in the northeast Washington assessment area (table 14). Five surrogate 

species (northern bog lemming, larch mountain salamander, western gray squirrel, 

Townsend’s big-eared bat, and fringed myotis) had such limited distributions within 

the assessment area that we did not develop formal models. For these species, we 

summarized available literature on their habitats, risk factors, and conservation 

status to offer management considerations. 

All surrogate species that we assessed showed lower viability outcomes under 

current conditions compared to historical conditions (table 15). The species for 

which current viability outcomes are most similar to historical viability outcomes 

include the golden eagle, Harlequin duck, northern goshawk, peregrine falcon, 

and Wilson’s snipe. Species for which current viability outcomes have departed 

the most from historical viability outcomes and are of greatest concern included 

the eared grebe, bighorn sheep, fox sparrow, sage thrasher, western bluebird, and 

white-headed woodpecker. Results of WI and VOI models and considerations for 

improving the viability for each species are provided in detail in chapters 2 and 3.

Surrogate-Species Assessment Model Evaluation

To evaluate our surrogate species assessment models, we conducted three levels of 

peer review and evaluated the scores from the WI models with independent data 

for a subset of surrogate species. For the peer reviews, we first convened a science 

team (app. 3) to provide input on our process, including the use of habitat relationships data, clustering procedure, surrogate species selection, and development and 

application of surrogate species assessment models. Second, we consulted species 

experts (app. 3) to help with the development of the species-specific models. These 

experts helped us determine which variables were most important to include in our 

We identified 52 

surrogate species for 

the national forests 

east of the Cascades 

Range in Oregon and 

Washington (Suring 

et al. 2011), which 

included 67 percent 

birds, 17 percent 

mammals, 14 percent 

amphibians, and 2 

percent reptiles.
37

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 14—Surrogate species for the northeast Washington assessment area 

Surrogate species Family/group association Focal type Okanogan Wenatchee Colville

Water vole Boreal forest F X X X

Northern bog lemming Boreal forest f X X X

Canada lynx Boreal forest F* X X X

Northern goshawk Medium-large trees/all forest communities F X X X

Cassin’s finch Medium-large trees/all forest communities F X X X

Larch mountain salamander Medium-large trees/cool-moist forest f X

Pileated woodpecker Medium-large trees/cool-moist forest F X X X

American marten Medium-large trees/cool-moist forest F X X X

White-headed woodpecker Medium-large trees/dry forest F X X X

Western bluebird Open forest/all forest communities F X X X

Fringed myotis Open forest/all forest communities F X X X

Fox sparrow Open forest/early successional F X X X

Western gray squirrel Open forest/pine/oak (medium-large trees) f X X

Lewis’s woodpecker Open forest/postfire F X X X

Black-backed woodpecker Open forest/postfire F X X X

Peregrine falcon Habitat generalist/cliff F X X X

Wolverine Habitat generalist F X X X

Golden eagle Woodland/grass/shrub F X X X

Lark sparrow Woodland/grass/shrub F X X X

Sage thrasher Shrub F* X X X

Tiger salamander Grass/shrub f X X X

Bighorn sheep Grass/shrub f X X X

Northern harrier Grassland F* X X X

Townsend’s big-eared bat Chambers/caves f X

Inland tailed frog Conifer riparian F X X

Wood duck Snag/open water F X X X

Harlequin duck Riparian/large tree f X X X

Bald eagle Riparian/large tree F X X X

Red-naped sapsucker Shrubby/deciduous riparian F X X X

MacGillivray’s warbler Shrubby/deciduous riparian F X X X

Columbian spotted frog Pond/small lake/backwater F* X X X

Wilson’s snipe Marsh/wet meadow F X X X

Eared grebe Marsh/open water F X X X

F = a surrogate species for the habitat group that should be addressed in the development of management actions, F* = a choice of surrogate species for 

managers to use primarily based on the distribution of the surrogate species, f = a surrogate species with localized populations that were confined to 

very specific habitats.

X = viability for the surrogate species was assessed. Whether or not a species was assessed for each forest was based on the distribution of the 

species (e.g., the inland tailed frog does not occur on the Colville National Forest).
38

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 15—Current (Cur) and historical (Hist) viability outcomes for surrogate species assessed 

in the northeastern Washington assessment area

Probability of viability outcome

A B C D E

Surrogate species Cur Hist Cur Hist Cur Hist Cur Hist Cur Hist

American marten 1 59 37 30 36 8 22 2 4 0

Bald eagle 0 76 23 16 73 7 4 1 0 0

Bighorn sheep 0 51 0 33 53 12 45 4 2 0

Black-backed woodpecker 9 81 25 13 40 5 26 1 0 0

Canada lynx 4 71 65 19 26 9 6 1 0 0

Cassin’s finch 0 81 0 13 40 5 60 1 0 0

Columbia spotted frog 0 71 22 19 72 9 6 1 0 0

Eared grebe 0 0 0 20 0 47 28 33 72 0

Fox sparrow 0 86 0 10 0 3 20 1 80 0

Golden eagle 32 81 56 13 8 5 4 1 0 0

Harlequin duck 34 81 57 13 6 5 3 1 0 0

Lark sparrow 0 71 3 19 45 9 52 1 0 0

Lewis’s woodpecker 0 76 0 16 60 7 40 1 0 0

MacGillivray’s warbler 0 76 22 16 73 7 5 1 0 0

Marsh wren 0 59 21 27 71 14 8 2 0 0

Northern goshawk 28 81 54 13 12 5 6 1 0 0

Northern harrier 0 71 22 19 72 9 6 1 6 0

Peregrine falcon 32 76 56 16 8 7 4 1 0 0

Pileated woodpecker 0 81 21 13 71 5 8 1 0 0

Sage thrasher 0 67 0 21 10 10 50 2 40 0

Tailed frog 0 76 23 16 73 7 4 1 0 0

Tiger salamander 0 67 21 22 71 10 8 2 0 0

Western bluebird 0 76 0 16 6 7 66 1 28 0

White-headed woodpecker 0 76 0 16 3 7 50 1 47 0

Wilson’s snipe 28 57 54 27 12 14 6 2 0 0

Wolverine 5 79 68 15 22 5 5 1 0 0

Wood duck 0 71 22 19 72 9 6 1 0 0
39

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

models, the best way to try to quantify the relationship between the variables, and 

likely outcomes for the species detailed in the conditional probability tables. Finally, 

we convened teams of field biologists (app. 3) familiar with the habitat conditions 

for surrogate species to provide feedback on the relative ranks of watersheds, as 

assigned by the models, to contribute to the conservation of several of the surrogate 

species. Following each of these reviews, the surrogate species assessment models 

were adjusted to better reflect scientific understanding of the relationship between 

the surrogate species and important variables that influenced their viability.

We statistically tested the WI models for a subset of surrogate species for which 

we had adequate species occurrence data. We obtained data from the Washington 

Department of Fish and Wildlife Heritage Database (WDFW 2006). This database 

contains occurrence data for a wide variety of wildlife species. We only assessed 

species for which we had a minimum of 30 verified locations that have occurred 

since 1990. This enabled us to evaluate models for the northern goshawk (674 

records), tailed frog (279 records), bald eagle (153 records), golden eagle (296 

records), wolverine (64 records), and peregrine falcon (33 records). For the whiteheaded woodpecker (88 records), we used information on species locations compiled by Mellen-McLean et al. (2013). We compared the WI scores associated with 

the locations of the recorded occurrences to an equal number of random locations. 

Our assumption was that the mean WI values from the occurrence points would be 

greater than the mean WI values generated from the random points if our models 

were operating as intended. We used 2-sample t-tests for unequal variances to 

compare the average values of the WI scores associated with the species occurrence 

data to those of the random points (Snedecor and Cochran 1989). 

Results from five of the seven surrogate species assessment models showed 

statistically significant support for the hypothesis that the mean WI values generated from the species occurrence points were greater than those generated from 

random points (table 16). An additional model (bald eagle) had mean WI values 

that were greater from the occurrence points compared to the random points, but 

this result was not statistically significant. The final model we evaluated was for 

the white-headed woodpecker. We believe that the WI values were so low for all 

watersheds that there was an insufficient distribution of values to make our statistical approach meaningful. These results suggest that our modeling approach worked 

well overall, adding confidence in results from species we did not have occurrence 

data to evaluate.
40

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 16—Results of surrogate species model evaluations

Species

Surrogate species 

occurrences

Random 

point

Mean 

WI occ.

Mean 

WI rand. t, P

- - - - - - - Number - - - - - - -

Tailed frog 279 146 1.89 1.71 1.97, 0.0008

Northern goshawk 674 674 1.72 1.56 1.96, <0.0001

Peregrine falcon 33 33 1.89 1.33 2.00, 0.004

Wolverine 64 63 2.01 1.58 1.98, <0.0001

Golden eagle 296 296 1.251 0.905 -8.827, <0.001

Bald eagle 153 153 1.612 1.588 -0.494, 0.622

White-headed woodpecker 88 88 0.16 0.17 1.97, 0.78

WI = watershed index. 
41

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Chapter 2: Individual Surrogate Species 

Assessments

American Marten

Introduction

Significant declines in the distribution of many carnivore species have occurred 

across North America since the arrival of Europeans (Giblisco 1994, Laliberte 

and Ripple 2004) with major reductions in marten populations resulting from the 

fur trade and timber harvest (Giblisco 1994). Despite protection of martens from 

trapping since 1953, continued habitat loss has led to increased concern for martens 

in the West (Ruggiero et al. 1994, 2007; Zielinski et al. 2001). American martens 

have a wide distribution across the western and eastern portions of the assessment 

area (Johnson and Cassidy 1997) and large home ranges, making them a good surrogate species to represent landscape characteristics of the cold-moist forests group 

in the medium/large trees family. Martens are associated with large trees, snags, 

and coarse woody debris (CWD), all of which are affected by timber management 

practices. Martens also have risk factors associated with human disturbance and 

roads. American martens were year-round residents of the assessment area; this 

assessment was for year-round habitats.

Model Description

Source habitat— 

For the purpose of this analysis, source habitat for both current and historical conditions was considered to be cold-moist and cold-dry forests (i.e., subalpine fir [Abies 

lasiocarpa], grand fir [A. grandis], Pacific silver fir [A. amabilis], Engelmann spruce 

[Picea englemanni], western hemlock [Tsuga heterophylla], mountain hemlock [T. 

mertensiana], and western redcedar [Thuja plicata]) with multistories, large-tree 

structure, quadratic mean diameters (QMDs) >16 in and closed canopies (i.e., >50 

percent). This designation of source habitat was based on associations of medium 

and large trees (i.e., >14 in diameter at breast height [d.b.h.]) and closed-canopy 

overstory vegetation in coniferous forests with martens, which were reported in 

the literature (Bull and Heater 2000, Buskirk et al. 1989, Campbell 1979, Gosse 

et al. 2005, Kirk and Zielinski 2009, Koehler et al. 1975, Martin 1987, Nams and 

Bourgeois 2004, Wilbert et al. 2000).

This source habitat described above is assumed to have high snag and CWD 

densities. Marten habitat values associated with varying snag densities have been 

documented in several studies (Gilbert et al. 1997, Martin and Barrett 1991, Payer 

and Harrison 1999, Ruggiero et al. 1998). Martin and Barrett (1991) found 16 logs 
42

GENERAL TECHNICAL REPORT PNW-GTR-907

per acre within habitats used by martens. Woody structures used for resting were 

large, with a mean d.b.h. of 36.7 in for live trees, 37.3 in for snags, and 34.7 in 

maximum diameter for logs with a mean density of CWD of 5.3 per acre (Buskirk 

et al. 1989, Slauson and Zielinski 2009). The mean age of trees at 24 of the resting 

sites was 339 years (range 131 to 666 years). Natal den sites were found to have 

47 pieces of CWD per acre, and maternal den site had 36 pieces of CWD per acre 

(Ruggiero et al. 1998). Gilbert et al. (1997) found 61 logs per acre at den and rest 

sites. Marten avoided plots with low densities of CWD, whereas plots with high to 

very high densities were selected by martens (Spencer et al. 1983). Log densities of 

8 to 29 per acre were considered optimum (Martin 1987). Andruskiw et al. (2008) 

showed that the frequency of prey encounter, prey attack, and prey kill were higher 

in old uncut forests for American martens, despite the fact that small-mammal 

density was similar to that in younger logged forests. These differences in predation 

efficiency were linked to higher abundance of CWD, which seems to offer sensory 

cues to martens, thereby increasing the odds of hunting success.

Patch size— 

Snyder and Bissonette (1987) reported limited use by martens of patches <6 ac of 

suitable habitat. Patches used by resident martens were 18 times larger (median = 

11 ac) than patches that were not used (median = 0.2 ac) and were closer to adjacent 

forest preserves (Chapin et al. 1998). Median size of largest forest patch in martens’ home ranges was 61 ac for females and 100 ac for males (Chapin et al. 1998). 

Similarly, Slauson et al. (2007) reported a minimum patch size used by American 

martens of >33 ac with a mean patch size of 73 ac. Potvin et al. (2000) recommended that uncut forest patches be >40 ac to maximize core area and to minimize edge. 

Generally, more habitat, larger patch sizes, and larger areas of interior forest were 

important predictors of occurrence (Chapin et al. 1998, Hargis et al. 1999, Kirk 

and Zielinski 2009, Potvin et al. 2000). Based on those findings, the following 

classes were used to describe the mean patch size of source habitat within watersheds (fig. 4):

• Low: <6 ac mean patch size of source habitat within a watershed

• Moderate: 6 to 40 ac mean patch size of source habitat within a watershed

• High: >40 ac mean patch size of source habitat within a watershed

Riparian habitat— 

Martens select for riparian habitats throughout their range (Anthony et al. 2003, 

Baldwin and Bender 2008, Buskirk et al. 1989, Martin 1987) and habitats near 

water (Bull et al. 2005). Fecske et al. (2002) characterized this relationship by 

distinguishing areas that were less than and greater than 330 ft from streams. The 
43

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Figure 4—Surrogate species assessment model for American marten.

suitability of riparian habitat was evaluated in this analysis by determining what 

percentage of the total area within 330 ft of streams (i.e., perennial, orders 3 to 8) 

was source habitat on a watershed basis and then placing watersheds in the following classes (fig. 4):

• Low: <25 percent of a watershed within 330-ft buffers was source habitat

• Moderate: 25 to 50 percent of a watershed within 330-ft buffers was source 

habitat

• High: >50 percent of a watershed within 330-ft buffers was source habitat

Percentage of landscape open— 

Percentage of the landscape in openings was a primary factor in determining the 

quality of American marten habitat. Hargis and Bissonette (1997) and Hargis et al. 

(1999) reported very little use by martens in landscapes with 25 percent or greater 

in openings. Potvin et al. (2000) also reported that marten home ranges contained 

less than 30 to 35 percent clearcut openings. Clearcuts supported 0 to 33 percent of population levels of martens compared to nearby uncut forest (Snyder and 

Bissonette 1987, Soutiere 1979, Thompson et al. 1989). Marten population reductions of 67 percent were reported following removal of 60 percent of forest (Soutiere 

1979) and 90 percent with 90 percent forest removal (Thompson 1994). Chapin et 
44

GENERAL TECHNICAL REPORT PNW-GTR-907

al. (1998) reported that martens tolerated 20 percent (median value) of their home 

range in regenerating forest. More recently, Dumyahn et al. (2007) demonstrated 

that American martens did not establish home ranges unless ≥70 percent of an 

area was suitable habitat. Also, Broquet et al. (2006) found that the movement of 

American marten individuals and gene flow through logged landscapes did not follow a linear, shortest-path movement. Rather, movement corresponded to a leastcost path that avoided openings. The following classes were developed from those 

findings and used to characterize watersheds (fig. 4):

• Low: 0.0 to 10.0 percent of a watershed in open condition

• Moderate: 10.1 to 30.0 percent of a watershed in open condition

• High: >30 percent of a watershed in open condition

Vegetation types were considered “closed” for this analysis if they had a tree 

canopy (i.e., ≥10 percent tree cover in the overstory layer). “Open” vegetation 

classes were all vegetation types without a tree canopy.

Habitat effectiveness— 

Hodgman et al. (1994) reported 90 percent of marten mortality resulted from trapping on an area with a road density of 0.42 mi/mi2

. Thompson (1994) also reported 

that trapping was the major source of mortality for martens. He also observed that 

predation and trapping mortality rates were higher in logged forests (with road 

development) than in uncut forests. Alexander and Waters (2000) observed avoidance by martens of areas within 160 ft of roads. Roads also facilitate the removal 

of snags as firewood and for safety considerations (Bates et al. 2007, Gaines et al. 

2003, Wisdom and Bate 2008). The findings of Godbout and Ouellet (2008) indicated that increasing road density results in lower quality habitat for American martens. Webb and Boyce (2009) showed that increased disturbance, particularly road 

access and oil and gas well sites, negatively affected habitats of American martens and reduced trapper success. The following density classes were summarized 

within source habitat by watershed (fig. 4):

• Zero: <0.1 mi/mi2

 of open roads

• Low: 0.1 to 1.0 mi/mi2 of open roads

• Moderate: 1.1 to 2.0 mi/mi2 of open roads

• High: >2.0 mi/mi2 of open roads
45

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Calculation of historical conditions— 

Values of the model variables were set with the following values to estimate historical habitat conditions:

• Departure of source habitat from natural range of variability (NRV)—0.5

• Patch size: Class increase from current condition

• Riparian habitat: Same as current condition

• Percentage of landscape open: Same as current condition

• Road density: Class zero

Geographic information systems (GIS) databases used—

• Cover type

• Source habitat (departure from NRV)

• Patch size

• Riparian

• Percentage of landscape open

• Canopy cover

• Quadratic mean diameter

• Streams

• Riparian

• Road density

The relative sensitivity of the watershed index (WI) values to the variables used 

in the American marten model are shown in table 17.

Watershed scores— 

This analysis indicated that 64 of 72 (89 percent) watersheds within the assessment 

area provided habitat for American martens (fig. 5). Forty-eight (75 percent) of the 

watersheds with habitat were well below their historical median levels of source 

habitat (i.e., < -1 class), while 16 (25 percent) of the watersheds were at or above 

historical median levels (i.e., > -1 class) (fig. 5). Watersheds that currently have the 

Table 17—Relative sensitivity of watershed 

index values to variables in the model for 

American marten

Variable Sensitivity rank

Habitat departure (amount) 1

Road density 2

Percentage of landscape open 3

Patch size 4

Riparian habitat 5
46

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 5—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, (D) and habitat 

condition class for American marten (AMMA) by watershed in the northeast Washington assessment area (NEWA).
47

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

greatest amount of source habitat included Cle Elum River, Chiwawa River, Icicle 

Creek, Little Naches River, Ross Lake, Upper Tieton River, Upper Yakima River, 

and White-Little Wenatchee (fig. 5). The watersheds with the least amount of source 

habitat were located across the eastern and northern portions of the assessment 

area. Wisdom et al. (2000) also reported strongly negative trends in the amount of 

source habitat across the northern portion of the North Cascades ecological reporting unit (ERU) (northern Okanogan National Forest) and across the Northern 

Glaciated Mountains ERU (Colville National Forest).

Currently, 20 percent (n = 13) of the watersheds with source habitat had WI 

scores that were high (i.e., >2.0) (fig. 5). All of these were located on the Wenatchee 

National Forest portion of the assessment area. Eleven (17 percent) additional 

watersheds had WI scores that were moderate (i.e., >1.0 to <2.0). Again, these were 

distributed on the Wenatchee National Forest portion of the assessment area.

We assessed the effect of size of patches of source habitat by calculating the 

mean patch size of source habitat within each watershed. This analysis showed that 

average patch sizes within watersheds ranged from <0.4 to >2.4 ha. All watersheds, 

but one (Icicle Creek) had low (<37 ac) average source habitat patch sizes. In addition, the percentage of the landscape classified as open in this analysis ranged from 

<2 to >87 percent. Thirteen of the watersheds had low (<10 percent open) levels of 

open landscape, 24 moderate (10.1 to 30.0 percent open), and 27 high (>30 percent 

open).

The percentage of 330-ft stream buffers in source habitat ranged from <1 to 

>30 percent across all watersheds in this analysis. All watersheds but six (American 

River, Bumping River, Chiwawa River, Little Naches River, Stehekin, and WhiteLittle Wenatchee) had low (i.e., <25 percent) amounts of source habitat within the 

riparian zone.

Six of the watersheds in the assessment area did not have any open roads in 

marten source habitat. The percentage of source habitat in watersheds with high 

open road densities ranged from 0.0 to 100.

Viability outcome scores— 

The viability outcome index (VOI) model incorporated the weighted watershed 

index (WWI) scores (described earlier), a habitat distribution index, and a habitat connectivity or permeability index. The WWI scores indicated that the current 

habitat capability within the assessment area for American martens was 76 percent 

of the historical capability. The ability of American martens to disperse across the 

assessment area was considered an issue for this species, thus we calculated permeability across the assessment area. The results were 41 percent of the assessment 

area had a low permeability for dispersal, 39 percent moderate, 20 percent high. 
48

GENERAL TECHNICAL REPORT PNW-GTR-907

All five ecoregions contained at least one watershed with >40 percent of the median 

amount of historical source habitat (the median was calculated across all watersheds 

with source habitat). Thirty-one percent (n = 22) of watersheds had >40 percent of 

the median amount of historical source habitat. Under those circumstances, there 

was a 37.0 percent probability that the current viability outcome for American 

marten was class B and a 35.8 percent probability the outcome was class C (fig. 6). 

It is likely that the other species associated with the cold-moist forests group in the 

medium/large trees family had similar outcomes.

Dispersal across the assessment area was also an issue for this species historically (38 percent of the assessment area had a low permeability for dispersal, 34 

percent moderate, 28 percent high). Historically, all five ecoregions contained ≥1 

watersheds with >40 percent of the median amount of historical source habitat 

(the median was calculated across all watersheds with source habitat). Seventy-six 

percent (n = 55) of watersheds had >40 percent of the median amount of historical 

source habitat. Under those circumstances, there was a 58.6 percent probability that 

the historical viability outcome for American marten was class A and a 30.5 percent 

probability that the historical outcome was class B (fig. 6).

In summary, under historical conditions, there was a high probability that 

viable populations of American martens and other species associated with the coldmoist forests group in the medium/large trees family were well distributed throughout the assessment area. The effects of development and habitat change across the 

assessment area has led to a lower probability that populations of American martens 

and all other species associated with the cold-moist forests group in the medium/

large trees family were viable and a finding that they were likely well-distributed in 

only a portion of the assessment area.

Figure 6—Current and historical viability outcomes for American martens in the northeast 

Washington assessment area.

In summary, under 

historical conditions, 

there was a high 

probability that 

viable populations 

of American martens 

and other species 

associated with the 

cold moist forests 

group in the medium/

large trees family 

were well distributed 

throughout the 

assessment area.
49

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Our results for this species were similar to those reported in the broad-scale 

habitat analysis by Wisdom et al. (2000) in the Interior Columbia Basin Ecosystem 

Management Project (ICBEMP). According to the ICBEMP terrestrial vertebrate 

habitat analyses, historical source habitats for American martens included portions 

of the Northern Cascades and the Northern Glaciated Mountains ERUs that overlap 

our assessment area (Wisdom et al. 2000). Within this historical habitat, declines in 

source habitats have been extensive, -60 percent in the Northern Cascades and -88 

percent in the Northern Glaciated Mountains according to Wisdom et al. (2000).

Management Considerations

The following management issues for American martens and all other species 

associated with the cold-moist forests group in the medium/large trees family were 

identified during this assessment and from the published literature for considerations by managers:

1. Reduction and fragmentation of old-forest habitats.

2. Negative effects of roads in source habitats.

3. The sustainability of dry forest habitats adjacent to source habitats for species associated with the cold-moist forests group in the medium/large trees 

family is a concern owing to risk of fire spreading from dry habitats into 

these source habitats (Townsley et al. 2004).

Bald Eagle 

Introduction

The bald eagle was chosen as a surrogate species for the riparian family and the large 

tree or snag/open water group. Bald eagles were recently removed from U.S. Fish 

and Wildlife (USFWS) federal list of threatened and endangered species (Stinson et 

al. 2007). The primary risk factor identified for the bald eagle is human disturbance. 

In Washington, bald eagles nest primarily west of the Cascade Range, with scattered 

breeding areas along major rivers in the eastern part of the state (Stinson et al. 2007, 

Watson and Rodrick 2000). Wintering eagles occur along the upper and lower Columbia River and its tributaries, with major wintering concentrations located along rivers 

with salmon runs (Stinson et al. 2007, Watson and Rodrick 2000). 

Model Description

Source habitat— 

Breeding territories for bald eagles are established in upland woodlands and lowland riparian stands with a mature conifer or hardwood component (Anthony 

and Isaacs 1989, Garrett et al. 1993, Watson and Pierce 1998). Territory size and 
50

GENERAL TECHNICAL REPORT PNW-GTR-907

configuration are influenced by factors such as density of breeding bald eagles 

(Gerrard and Bortolotti 1988), quality of foraging habitat, and the availability of 

prey (Watson and Pierce 1998). The three main factors that influence the location of 

nests and territories include proximity of water and availability of food; availability 

of nesting, perching, and roosting trees; and the density of breeding-age bald eagles 

in the area (Stalmaster 1987). Anthony and Isaacs (1989) reported that nest sites in 

older contiguous forest habitats with low levels of human disturbance resulted in 

higher levels of bald eagle productivity.

We modeled source habitat for bald eagles using a combination of tree structure 

(e.g., canopy layers and canopy closure) and size class, elevation, and proximity to 

water bodies described in the literature listed above. Our model of source habitat 

included the following:

• Elevation: <3,000 ft 

• Waterbody: Waterbodies >5 ac (including large stream reaches)

• Distance from suitable-sized waterbody: 984-ft buffer 

• Tree structure and size classes: Single and multistory, >15 in d.b.h. 

calculated as the QMD 

The current habitat departure class for the bald eagle was set at -1 class for all 

watersheds (see page 17 calculation of reference condition). 

Late-successional forest— 

Several studies have reported the importance of late-successional forests in defining 

quality of nesting habitat and influencing productivity of bald eagles (Anthony and 

Isaacs 1989, Garrett et al. 1993). We included the amount of potential source habitat 

that was in a late-successional forest condition as a factor that affected habitat quality (fig. 7). We used the following GIS data layers to map late-successional forest as 

a subset of the total potential source habitat:

• Single and multistory forests, >20 in d.b.h. (calculated as QMD) 

• Canopy closure >50 percent

We then used the following categories in our model to categorize the proportion 

of source habitat within a watershed composed of late-successional habitat:

• Zero: No source habitat is late successional

• Low: >0 to 20 percent of the source habitat is composed of late-successional forest

• Moderate: >20 to 50 percent of the source habitat is composed of latesuccessional forest

• High: >50 percent of the source habitat is composed of late-successional forest
51

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Habitat effectiveness— 

Reported responses of bald eagles to human disturbances have ranged from spatial 

avoidance of the activity to reproductive failure (Anthony et al. 1995, Buehler et 

al. 1991, McGarigal et al. 1991, Watson 1993), although in some cases, bald eagles 

tolerate human disturbances (Harmata and Oakleaf 1992). Bald eagles seem to be 

more sensitive to humans afoot than to vehicular traffic (Grubb and King 1991, 

Skagen et al. 1991, Stalmaster and Newman 1978). Fletcher et al. (1999) reported 

that the abundance of bald eagles was lower in riparian habitats with nonmotorized 

trails compared to riparian habitats without trails. Recommended buffer distances 

to reduce the potential for disturbance to bald eagles during the nesting period have 

ranged from 984 to 2,624 ft (Anthony and Isaacs 1989, Fraser et al. 1985, Stalmaster 

1987). Grubb and King (1991) evaluated the influence of pedestrian traffic and vehicle traffic on bald eagle nesting activities and recommended buffers of 1,800 ft for 

pedestrians and 1,500 ft for vehicles.

We included a habitat effectiveness variable in the bald eagle model to assess 

the potential influence of human activities on source habitats. We used the bald 

eagle nesting habitat disturbance index described in Gaines et al. (2003a). To do 

Figure 7—Surrogate species assessment model for the bald eagle.
52

GENERAL TECHNICAL REPORT PNW-GTR-907

this, we buffered roads and motorized trails by 1,500 ft on each side and nonmotorized trails by 1,800 ft on each side to establish zones of influence. Next, we 

intersected this with our maps of source habitat to determine the proportion of 

source habitat within each watershed that was inside a zone of influence. We then 

developed the following categories to assess the potential influences of increasing 

proportions of source habitat within a zone of influence (fig. 7):

• Low habitat effectiveness: <30 percent of the source habitat outside of a 

zone of influence.

• Moderate habitat effectiveness: 30 to 50 percent of the source habitat outside of a zone of influence.

• High habitat effectiveness = >50 percent of the source habitat outside of a 

zone of influence.

Calculation of historical conditions—

• Historical habitat departure: Departure class 1 assumed no departure from 

historical conditions.

• Late-successional forest: Moderate

• Habitat effectiveness: High

The relative sensitivity of WI values to variables in the model for bald eagles is 

shown in table 18.

Model evaluation— 

We used 153 bald eagle occurrence points and 153 random points to evaluate the 

surrogate species assessment model. The mean WI value derived from the occurrence points was 1.612 and the mean WI value derived from the random points was 

1.588. While the trend showed slightly better WI values for the occurrence points, 

this was not a statistically significant result (t = -0.494, P = 0.622).

Table 18—Relative sensitivity of 

watershed index values to variables in 

the model for the bald eagle

Model variables

Order of 

variable weighting

Source habitat 1

Late-successional forest 2

Habitat effectiveness 3
53

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Assessment Results

Watershed scores— 

This analysis showed that 60 of 72 (83 percent) watersheds within the assessment 

area had habitat. Thirteen percent (n = 8) of the watersheds assessed had high WI 

scores (>2.0), and an additional 62 percent (n = 39) had moderate scores (>1.5 to 

2.0). The watersheds with a high WI score were Curlew, Upper Okanogan River, 

Mill, Sinlahekin Creek, Stensgar/Stranger, Lower Okanogan River, Ross Lake, and 

Stehekin River. 

The median amount of source habitat across all watersheds was 238.5 ac. 

Watersheds with the most source habitat (>1,200 ac) included Cle Elum, Entiat, 

White-Little Wenatchee, Wenatchee, Chiwawa, and Upper Yakima Rivers. Because 

this is a riparian species, habitat departure for all watersheds was classified in the -1 

departure class.

The percentage of late-successional forest within source habitat was low and 

reduced the habitat quality in most watersheds. One-third (n = 21) of the watersheds 

did not have late-successional forest within source habitat, 54 percent (n = 34) had 

low levels (>0 to 20 percent of the source habitat), 8 percent (n = 5) had moderate 

levels (>20 to 50 percent of the source habitat), and only 5 percent (n = 3) had high 

(>50 percent) levels of late-successional forest in source habitat. The watersheds 

with high levels of late-successional forests are Lightning Creek, Ruby Creek, and 

Ross Lake.

Model results indicate that human activities are having a large impact on the 

effectiveness of source habitat for bald eagles across the assessment area. Activities 

associated with roads and trails have reduced habitat effectiveness to low levels in 

68 percent (n = 43) of the watersheds and moderate levels in 19 percent (n = 12) of 

the watersheds. Only 13 percent (n = 8) of the watersheds assessed had a high level 

of habitat effectiveness within bald eagle source habitat. 

Viability outcome scores— 

The VOI model incorporated the WWI scores, and a habitat distribution index. 

The WWI scores indicated that the current habitat capability for bald eagles within 

the assessment area is 56 percent of the historical capability. This score is largely 

influenced by the effects of human activities within or adjacent to bald eagle habitat. Seventy-two percent of the watersheds (n = 52) had both current and historical 

amounts of source habitat >40 percent of the historical median, and they were distributed across all ecoregions.
54

GENERAL TECHNICAL REPORT PNW-GTR-907

There is a 73 percent probability that the current viability outcome for the bald 

eagle is C, which suggests that suitable environments for bald eagles are distributed 

frequently as patches or exist in low abundance (fig. 8). Species with this outcome 

are likely well-distributed in only a portion of the assessment area. Historically, 

there was a 76 percent probability that the viability outcome was A, where suitable 

environments were more broadly distributed or of high abundance. In addition, the 

suitable environments were better connected, allowing for interspecific interactions. A reduction in the availability of suitable environments for the bald eagle may 

have occurred in the assessment area compared to the historical distribution and 

condition of their habitats. 

Gaines et al. (2003a) found that roads and other human activities have had a 

disproportionately high impact on riparian habitats owing to their proximity to 

riparian areas. This result is the same for the bald eagle as well as other species 

associated with streamside forested riparian habitats such as the harlequin duck and 

tailed frog (see pages 118 and 185 of this assessment). 

Management Considerations

The following issues were identified during this assessment and from the published 

literature regarding the viability of populations of bald eagle and likely other 

species in the riparian family and the large tree or snag/open water group for the 

considerations of managers:

1. Low availability of late-successional forest within riparian source habitat.

2. Human activities reduced the effectiveness of source habitats.

Figure 8—Current and historical viability outcomes for the bald eagle in the northeast Washington 

assessment area.

A reduction in the 

availability of suitable 

environments for 

the bald eagle may 

have occurred in the 

assessment area 

compared to the 

historical distribution 

and condition of their 

habitats.
55

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Bighorn Sheep

Introduction

Bighorn sheep were selected as surrogate species to represent the grassland/

shrubland group. They are distributed across the assessment area in nine herds, 

each with a limited range. Many of these herds are a result of efforts to reintroduce 

bighorn sheep populations throughout eastern Washington following their extirpation. Historically, California bighorn sheep occurred on the eastern slopes of the 

Cascade Range from the Canadian border south to the Columbia River. Most of the 

herds were gone before 1900; the last known survivors, on Chopaka, died in 1925 

(Johnson 1999). Rocky Mountain bighorn sheep occurred historically in the Selkirk 

Mountains but were extirpated from this area by the late 1800s (Johnson 1999). 

Currently, there are around 550 to 675 Rocky Mountain and California bighorn 

sheep within the assessment area (table 19); this assessment was for year-round 

habitats.

Model Description

Source habitat— 

Previous studies have used GIS to model bighorn sheep habitat (Cassirer et al. 1997, 

Johnson and Swift 2000, Smith et al. 1991, Zeigenfuss et al. 2000). Source habitat for bighorn sheep was modeled by Begley (2008) using logistic regression and

telemetry data from the Swakane bighorn sheep herd located in the central portion

of the assessment area. The model was then extrapolated across the assessment area, 

Table 19—Estimated sizes of the bighorn sheep populations 

in the herds located in the northeast Washington assessment 

areaa 

Herd name Estimated numbers Adjacent national forest

Tieton 33 to 41 Okanogan-Wenatchee

Clemens Mountain 140 to 172 Okanogan-Wenatchee

Umtanum 156 to 190 Okanogan-Wenatchee

Swakane 48 to 58 Okanogan-Wenatchee

Lake Chelan 41 to 51 Okanogan-Wenatchee

Sinlahekin 27 to 33 Okanogan-Wenatchee

Mount Hull 59 to 72 Okanogan-Wenatchee

Vulcan Mountain 21 to 27 Colville

Hall Mountain 26 to 33 Colville

a

 Based on WDFW (2008).
56

GENERAL TECHNICAL REPORT PNW-GTR-907

and telemetry data from the Tieton and Vulcan herds were used to test the extrapolated model. The variables that were identified in the model included vegetation zones, 

canopy closure, and escape terrain (Begley 2008). Based on this, source habitat within the assessment area was mapped using the following spatial data sources (fig. 9).

• Vegetation zones: Douglas-fir, ponderosa pine, and shrub-steppe cover 

types within 1,600 ft of escape terrain

• Canopy closure: <60 percent

• Escape terrain: Area with slope between 31 and 85 degrees and >4.0 ac

Patch size— 

Several studies have shown that the size of a patch of suitable habitat can influence bighorn sheep occupancy, habitat use, success of reintroduction efforts, and 

population demographics (Cassirer et al. 1997, Gross et al. 2000, Johnson and Swift 

Figure 9—Bighorn sheep source habitat and dispersal habitat suitability.
57

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

2000, Singer et al. 2000, Zeigenfuss et al. 2000). Begley (2008) used an area (4 ac 

of escape terrain plus a 1,600-ft buffer) of about 200 ac in the habitat model. Based 

on this, a range of size categories was used to assess the quality of habitat patches 

within a watershed.

• Low: Average source habitat patch size in the watershed <100 ac

• Moderate: Average source habitat patch size in the watershed 100 to 400 ac

• High: Average source habitat patch size in the watershed >400 ac

Domestic sheep grazing— 

Domestic sheep overlapping or in proximity to bighorn sheep have been reported to 

result in the spread of Pasturella among bighorn sheep, with subsequent die-offs in 

bighorn sheep populations (Foreyt 1989, Foreyt and Jessup 1982, Foreyt et al. 1994, 

Schommer and Woolever 2008). Gross et al. (2000) showed that the risk of disease 

spread was a more important variable in determining the extinction rates of bighorn sheep than habitat restoration. Therefore, to evaluate the potential for disease 

spread, we assessed the area of active domestic sheep grazing allotments within 

1.0 mi of bighorn sheep source habitat for each watershed. This variable was then 

scaled from 0 percent overlap to 100 percent overlap in increments of 10 percent 

(fig. 10). Conditional probability tables were calibrated so that when >20 percent 

of the 1-mi-buffered source habitat within a watershed was in an active domestic 

sheep allotment, the risk of disease spread to bighorn sheep was considered high.

Figure 10—Surrogate species assessment model for bighorn sheep.
58

GENERAL TECHNICAL REPORT PNW-GTR-907

Habitat effectiveness— 

Bighorn sheep have been reported to respond to human disturbance (Hicks and 

Elder 1979; King and Workman 1986; Leslie and Douglas 1980; MacArthur et 

al. 1979, 1982; Papouchis et al. 2001; Smith et al. 1991). MacArthur et al. (1979) 

showed that the heart rate of bighorn sheep varies inversely with the distance from 

a road. MacArthur et al. (1982) reported that sheep were affected by a human approaching within 160 ft, and Papouchis et al. (2001) found that bighorn sheep 

respond to hikers at an average distance of 650 ft. They also showed avoidance of 

roads was greater for high-use (5 to 13 vehicles per hour) than low-use (1 vehicle 

per hour) roads. On average, radio-collared sheep were located 1,600 ft from highuse roads compared to 1,200 ft from low-use roads (Papouchis et al. 2001). Smith 

et al. (1991) developed a habitat suitability model for bighorn sheep and considered 

areas within 330 ft of low to moderate human use (<500 visitors per year) trails and 

roads as unsuitable, and areas within 490 ft of high human use (>500 visitors per 

year) trails and roads as unsuitable. Based on this information, Gaines et al. (2003a) 

developed a bighorn sheep habitat disturbance index that we used to assess habitat 

effectiveness. The index was based on a zone of influence on each side of roads or 

trails that was overlaid with the bighorn sheep source habitat to assess the proportion of source habitat within a zone of influence (table 20). 

We then categorized the amount of source habitat within the zone of influence 

to assess habitat effectiveness for each watershed as follows (based on Gaines et al. 

2003a) (fig. 10):

• High habitat effectiveness: >70 percent of the source habitat outside a zone 

of influence

• Moderate habitat effectiveness: 50 to 70 percent of the source habitat outside a zone of influence

• Low habitat effectiveness: <50 percent of the source habitat outside a zone 

of influence

Table 20—Zone of influence applied to each side 

of a trail or road based on road type and use level 

for bighorn sheep 

Trail or road type and status Zone of influencea

Feet

Nonmotorized trial (ski or hiking) 650

Motorized trail 1,150

Road <1 vehicle per day 1,150

Road >1 vehicle per day 1,640

a Based on Gaines et al. (2003).
59

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Calculation of historical conditions— 

Values of the surrogate species model variables were set with the following values 

to estimate historical habitat conditions: 

• Source habitat: Set at the 1 departure node

• Patch size: Assumed to be one category larger than current in order to estimate the effects of fire exclusion on the canopy-closure variable

• Domestic sheep grazing: Class zero

• Habitat effectiveness: Class high

The relative sensitivity of WI values to model variables for bighorn sheep is 

displayed in table 21.

Assessment Results

Watershed scores— 

Most, or 73 percent (n = 52) of the watersheds had moderate WI scores (1.0 to 2.0), 

while 8 percent (n = 6) had high (>2.0), and the remainder (18 percent, n = 13) had 

low (<1.0) scores. 

Watersheds with the greatest amount of source habitat (>19,000 ac) currently 

included the Upper Methow, Entiat, Upper Columbian-Swamp Creek, Sinlahekin, 

Columbia River-Lynch Coulee, Lake Entiat, Okanogan River-Omak Creek, and 

Lower Lake Chelan. Of these watersheds, the Lower Lake Chelan, Entiat River, and 

Upper Methow River had more than 60 percent of the source habitat on National 

Forest Systems lands. The median amount of source habitat across all watersheds 

was 5,379 ac. 

Average patch sizes of source habitat were high (>400 ac) in 14 percent (n = 10) 

of the watersheds, moderate (100 to 400 ac) in 24 percent (n = 17), and low (<100 

ac) in 62 percent. Fire exclusion has resulted in an increase in the density of trees in 

formerly open stands, reducing forage quality and causing bighorns to avoid these 

areas because of reduced visibility (Wisdom et al. 2000). 

Table 21—Relative sensitivity of watershed 

index values to variables in the model for 

bighorn sheep

Model variables

Order of 

variable weighting

Source habitat 1

Domestic sheep grazing 2

Habitat effectiveness 3

Patch size 4
60

GENERAL TECHNICAL REPORT PNW-GTR-907

Habitat effectiveness, indexed by assessing the amount of source habitat within 

a distance buffer of roads and trails was ranked low in 61 percent (n = 43) of the 

watersheds, moderate in 25 percent (n = 18), and high in only 14 percent (n = 10) of 

the watersheds. 

The potential for disease spread from domestic sheep to bighorn sheep was 

assessed by identifying the amount of source habitat within 1.0 mi of an active 

domestic sheep allotment. This assessment showed that 14 (20 percent) of the 

watersheds had >20 percent of the source habitat within 1.0 mi of an active grazing 

allotment and had the greatest effect on reducing the watershed scores. Watersheds 

with the highest proportions (>60 percent) of source habitat near or within active 

grazing allotments included the Bumping River, Little Naches, Mad River, Naches, 

Rattlesnake Creek, Sinlahekin Creek, and Wenas Creek. 

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI portion of the viability outcome model showed that 

the current habitat capability was at 57 percent of the historical habitat capability 

when calculated across all of the watersheds within the assessment area. The major 

factors that contributed to the decline in the habitat capability were the influence of 

human access on habitat effectiveness and the potential impact of disease transmission from domestic sheep grazing. 

Forty-seven (66 percent) of the watersheds had source habitat amounts above 

the 40 percent median (2,150 ac), and all of the ecoregions had one or more watersheds with more than 40 percent of the median. The habitat distribution index 

showed that 88 percent of the watersheds were classified as low permeability and 

12 percent as moderate (fig. 9).

The current viability outcome for bighorn sheep across the assessment area had 

a probability of 52 percent for outcome C and a 44 percent probability of outcome 

D, indicating that suitable environments are frequently isolated and that this species 

is not well distributed across the assessment area (fig. 11). Historically, the viability 

assessments showed a probability of 51 percent for outcome A and 33 percent for 

outcome B, indicating that bighorn sheep populations and habitat were well distributed and better connected across the assessment area compared to contemporary 

landscapes. 

Wisdom et al. (2000) found large declines in the amount of bighorn sheep habitat throughout the interior Columbia Basin including eastern Washington. Additionally, Raphael et al. (2001) showed a similar viability outcome using a similar habitat 
61

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

model, and reported downward trends in habitat quantity and quality for bighorn 

sheep for the entire interior Columbia Basin.

In summary, under historical conditions, there was a high probability that viable populations of bighorn sheep, and other species associated with the grassland/

shrubland group, were well distributed throughout the assessment area. Currently, 

populations are reasonably well distributed but relatively small and isolated across 

the assessment area.

Management Considerations

The following issues were identified during this assessment and from the 

published literature regarding the viability of populations of bighorn sheep 

across the assessment area for the consideration of managers:

1. Fire exclusion has resulted in an increase in the density of trees in formerly 

open stands, reducing forage quality and causing bighorns to avoid these 

areas because of reduced visibility.

2. The proximity of domestic sheep allotments adjacent to bighorn sheep 

source habitat has resulted in a potential to spread disease to some 

populations.

3. Human activities have reduced the effectiveness of bighorn sheep source 

habitat in several watersheds.

Figure 11—Current and historical viability outcomes for bighorn sheep in the northeast 

Washington assessment area.

In summary, under 

historical conditions, 

there was a high 

probability that 

viable populations 

of bighorn sheep, 

and other species 

associated with the 

grassland/shrubland 

group, were well 

distributed throughout 

the assessment area. 

Currently, populations 

are reasonably 

well distributed but 

relatively small and 

isolated across the 

assessment area.
62

GENERAL TECHNICAL REPORT PNW-GTR-907

Black-Backed Woodpecker

Introduction

Black-backed woodpeckers were chosen as surrogate species for the postfire group. 

They represent postfire habitat with a relatively high density of trees and snags, as 

compared to other species in the group (e.g., Lewis’s woodpecker). Black-backed 

woodpeckers have been reported to exist at higher densities and are more productive in postfire habitats than in other forest conditions in which they occur. They 

range across the assessment area and are sensitive to salvage activities, making 

them a good surrogate species. These birds are resident throughout the assessment 

area. 

Model Description

Source habitat— 

Black-backed woodpeckers are associated with boreal and montane coniferous 

forests, especially in areas with standing dead trees such as burns (Dixon and Saab 

2000). This bird is extremely restricted in its use of habitat types and is strongly 

associated with recently burned forests (Gentry et al. 2007, Hutto 2006, Nappi et 

al. 2003, Raphael and White 1984, Saab and Dudley 1998). In the northern Rocky 

Mountains of the United States, a regionwide landbird survey and extensive literature review revealed that the species is almost exclusively associated with recently 

burned forests (<5 years), although it is occasionally observed in mixed-conifer, 

lodgepole pine, Douglas-fir, and spruce-fir forests (Hutto 1995a, 1995b). Several 

studies have found that in recently burned forests, black-backed woodpecker nest 

sites were found at higher densities and had higher nest success in areas that were 

not salvage logged and had high densities of standing snags (Haggard and Gaines 

2001, Saab and Dudley 1998, Saab et al. 2009).

In California, these woodpeckers occurred in burned sites 6 to 8 years after 

fire, but were not recorded during surveys 15 to 19 years and 21 to 25 years 

postfire, although they were present in very low densities during all periods in 

unburned control plots (Raphael et al. 1987). Hutto (1995b) suggested that a mosaic 

of recently burned forests may best represent source habitat, where local reproduction exceeds mortality. Several researchers have suggested that the low densities of 

woodpeckers in unburned forests may indicate sink populations that are maintained 

by birds that move into these areas as conditions on postfire habitats become less 

suitable over time (Hutto 1995, Murphy and Lehnhausen 1998, Nappi et al. 2003, 

Saab et al. 2005). However, Goggans et al. (1988) suggested that this species be an 
63

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

indicator species for mature and old-growth lodgepole pine stands in Oregon, and 

Trembly et al. (2009) suggested the use of black-backed woodpecker as an indicator 

species in mature and overmature coniferous stands in northeastern North America.

For this species, we considered both a primary and secondary source habitat in 

all forested potential vegetation types. Primary source habitat was considered any 

postfire habitat from 1994 to 2003 that had not been salvage harvested. Secondary 

habitat was defined as forests with >10 in d.b.h. and >50 percent canopy closure. 

In addition, we included forested areas with a high degree of insect outbreak (e.g., 

bark-beetle-killed forests) over the past 10 years. Areas identified on the insect and 

disease map with >5.6 snags/acre and not harvested since 1994 were also included 

as secondary habitat (http://www.fs.fed.us/r6/nr/fid/as/index.shtml). The area within 

200 ft surrounding open roads was not considered primary or secondary habitat 

owing to the likelihood of reduced snag densities that result from firewood cutting 

and hazard tree felling (Bate et al. 2007, Wisdom and Bate 2008).

We identified primary source habitat as:

• Potential vegetation types: dry, mesic, cold-moist, and cold-dry forests

• Postfire habitat 1994–2003, that had not been salvage harvested in all 

forested cover types

We identified secondary source habitat as:

• Potential vegetation types: Dry, mesic, cold-moist and cold-dry forests

• Cover types: All forested types 

• Tree size: >25 in QMD 

• Tree canopy closure: >50 percent 

Snag densities— 

Black-backed woodpeckers nest in both live and dead trees but may require heartrot for nest excavation (Goggans 1989). Nests are usually in a conifer such as pine, 

spruce, fir, or Douglas-fir (Scott et al. 1977). In Idaho, used nest trees averaged 12.7 

in d.b.h. (N = 15; Saab and Dudley 1998). In a study in the Sierra Nevada, California, 

black-backed woodpeckers favored partially dead trees and hard snags for nesting; 

used nest trees >16 in d.b.h. and >42.6 ft tall in both burned and unburned forest 

(Raphael and White 1984). Mean d.b.h. of nest trees reported in this study was 16 in, 

nest-tree height 92 ft, and nest-cavity height averaged 36 ft. Of 15 nests in northeast 

Oregon, 9 nests were located in snags and 6 in live trees; most (10) were in ponderosa 

pine, 4 in lodgepole pine, and 1 in western larch (Bull et al. 1986). They also reported 

that nest trees averaged 14.5 in d.b.h., 62 ft in height, and 16 ft at nest-cavity height.
64

GENERAL TECHNICAL REPORT PNW-GTR-907

This woodpecker forages predominantly on wood-boring beetles, engraver 

beetles, and mountain pine beetles (Dixon and Saab 2000, Goggans et al. 1988, 

Harris 1982, Villard and Beninger 1993). In central Oregon, they foraged predominantly on lodgepole pine trees with a mean d.b.h. of 14 in ± 4.7 standard deviation 

(SD) (range 2 to 39, n = 330); dead trees were used in greater proportion than available, and most were recently dead; 81 percent of forage trees were infested with 

mountain pine beetle; mean foraging height 16 ft ± 11 SD (range 0 to 59, n = 339; 

Goggans et al. 1988). In a burned, mixed-conifer forest in northeast Washington, 

black-backed woodpeckers foraged on dead trees 99 percent of the time (Kreisel 

and Stein 1999). Woodpeckers as a group (included black-backed woodpeckers) 

selected trees or snags greater than 17 in d.b.h. to forage on in a foraging study on 

the Wenatchee National Forest (Lyons et al. 2008). 

We assumed that snag densities preferred by the species were available in 

primary habitat (unsalvaged postfire forest). In secondary habitat, we calculated the 

percentage of area of source habitat within each watershed that had snag densities 

(>10 in d.b.h.) in the following classes based on data from Mellen-McLean et al. 

(2009): low <4/ac, moderate 4.0 to 7/ac, high 7 to 18/ac, and very high >18 snags/

ac (fig. 12). The breaks between classes are based on averaged DECAID (MellenMcLean et al. 2009) data for ponderosa pine/Douglas-fir, mesic, and montane 

forests snags >10 in and expert opinion.

Road density— 

Snag numbers adjacent to roads are often lower owing to the felling of snags for 

safety considerations, firewood cutters, and other management activities (Bate et al. 

2007, Wisdom and Bate 2008). Other literature has reported the potential for 

reduced snag abundance along roads (Gaines et al. 2003a, Wisdom et al. 2000). 

To account for reduced snag density along all roads, we calculated the percentage 

of secondary source habitat in the following road density classes by watershed 

(fig. 12):

• Zero: <0.1 mi/mi2 open roads in a watershed

• Low: 0.1 to 1.0 mi/mi2 open roads in a watershed

• Moderate: 1.1 to 2.0 mi/mi2 open roads in a watershed

• High: >2.0 mi/mi2 open roads in a watershed

Historical inputs for surrogate species assessment model—

• Primary habitat departure: Class 1

• Secondary habitat departure: Class 1

• Snag density: High
65

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

The relative sensitivity of the WI values to variables in the model for the blackbacked woodpecker are shown in table 22.

Assessment Results

Watershed scores— 

Our analysis indicated that primary habitat was below the historical median in most 

watersheds ( n = 61, 85 percent) (fig. 13) indicating a lack of recent stand-replacing 

wildfires. The remaining 11 watersheds all experienced recent wildfires. The Lower 

Lake Chelan (32,120 ac) and Upper Chewuch (49,420 ac) watersheds have much 

higher amounts of primary source habitat than any other watersheds (fig. 13). It is 

likely that past fire management policies have negatively affected this species by 

reducing the number of large, high-intensity wildfires that create suitable conditions 

for the black-backed woodpecker (Dixon and Saab 2000). 

Figure 12—Surrogate species assessment model for black-backed woodpeckers.
66

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 22—Relative sensitivity of watershed index values 

to variables in the model for black-backed woodpecker

Variable Sensitivity rank 

Primary habitat departure 1

Secondary habitat departure 2

Snags secondary 3

Road density 4

Figure 13—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D), 

habitat condition class for black-backed woodpeckers by watershed in the northeast Washington assessment area.
67

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

The departure of secondary source habitat from historical conditions was 

more mixed, 44 percent (n = 32) watersheds were below the median range of variation, 38 percent were near the median (n = 27), and 18 percent (n = 13) were above 

(fig. 13). Declines in secondary source habitat are associated with decreases in the 

abundance of trees >10 in d.b.h. with >50 percent canopy closure. Wisdom et al. 

(2000), in the evaluation of source habitat for black-backed woodpeckers across the 

interior Columbia Basin, found similar overall declines in the habitat area of the 

Colville National Forest. However, they found an overall decline along the Cascade 

Range, where we found departure to be closer to the historical reference conditions. This difference likely can be explained by differences in definition of source 

habitats, except in the lodgepole pine types. Wisdom et al. (2000) defined source 

habitat in larger tree structural stages, while in this analysis, we included forests 

with >10 in d.b.h. 

Overall, snag densities in secondary source habitat were in the low class (<4/ac): 

57 percent (n = 41) of the watersheds had greater than half their source habitat in the 

low class. Seven watersheds had more than 70 percent of their source habitat in the 

low class: Columbia tributaries, upper Columbia–Swamp Creek, Middle Sanpoil, 

lower Okanogan River–Omak Creek, Columbia River-Lynch Coulee, and Cowiche. 

No watersheds had a majority of secondary habitat in the medium, high, or very 

high snag classes. 

Overall road densities were not high in secondary source habitat, though 15 

percent (n = 11) of watersheds showed greater than half the habitat area in high road 

density, with two watersheds having >70 percent of habitat in that watershed in a 

high class (Wenas Creek and Middle Yakima River). Twenty-nine percent (n = 21) 

of the watersheds had >50 percent of source habitat in the zero road density class. 

Because primary postfire habitat is well below the historical median in most 

watersheds, the amount of secondary habitat is likely playing an important role. In 

31 percent (n = 22) of the watersheds where both primary and secondary habitat 

were below the historical median, the WI value currently was <1 (fig. 13). Watersheds with an index >2.0, are thought to be less departed in the amount of habitat, 

and contain good quality habitat. Ten watersheds (14 percent) in the study area meet 

these criteria with a WI value >2.0. 

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability 

for black-backed woodpeckers within the assessment area is 81 percent of the historical capability. Currently, four of five ecoregions contain at least one watershed 
68

GENERAL TECHNICAL REPORT PNW-GTR-907

with >40 percent of the median amount of historical source habitat (median was calculated across all watersheds with source habitat). Fifteen of seventy-two (21 percent) watersheds had >40 percent of the historical median amount of source habitat.

Currently, the viability outcome falls primarily within outcomes C (40.5 percent), D (25.5 percent), and B (24.5 percent), which indicates that suitable environments are frequently patchily distributed, and source habitat is in low abundance 

(fig. 14). Historically, the outcome was primarily an A (80.8 percent) indicating 

that suitable environments were once abundant, broadly distributed, and better 

connected. 

Historically, all five ecoregions contained at least one watershed with >40 

percent of the median amount of historical source habitat (median was calculated 

across all watersheds with source habitat). Sixty-three watersheds (88 percent) had 

>40 percent of the median amount of historical source habitat.

The main factor leading to a lower viability outcome from historical was the 

decreased percentage of watersheds with recent wildfire activity (primary source 

habitat). Historically, 88 percent (n = 63) of the watersheds contained >40 percent 

of the historical median amount of primary habitat while primary habitat currently 

occurs in this quantity in only 21 percent (n = 15) of the watersheds. Fire suppression efforts likely reduced the amount and distribution of primary habitat for this 

species, and likely other species in the postfire group, leading to reduced viability. 

Figure 14—Current and historical viability outcomes for the black-backed woodpecker in 

the northeast Washington assessment area.

Fire suppression 

efforts likely reduced 

the amount and 

distribution of primary 

habitat for this species, 

and likely other species 

in the postfire group, 

leading to reduced 

viability.
69

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Low abundance of recent unsalvaged postfire habitat throughout the 

assessment area.

2. Decline in secondary source habitat in some areas.

3. Snag densities in secondary habitat were primarily low.

Canada Lynx

Introduction

The Canada lynx was selected as a surrogate species to represent the boreal forest 

group owing to its close association with boreal forests (Aubry et al. 2000, ILBT 

2013, Koehler and Aubry 1994, Maletzke 2004, von Keinast 2003) and because 

human disturbance was identified as a risk factor for lynx (Buskirk et al. 2000, 

ILBT 2013, Koehler and Aubry 1994, Koehler et al. 2008, Ruediger et al. 2000). 

The distribution of Canada lynx within the assessment area has been stratified 

into core, secondary, and peripheral habitat areas based on known records of their 

occurrences (ILBT 2013, USFWS 2005). Core areas occur on the OkanoganWenatchee National Forest, on the Methow Valley and Tonasket Ranger Districts, 

and in the Kettle Mountains on the Colville National Forest. The remainder of the 

Colville National Forest and the portion of the Okanogan-Wenatchee National Forest between Highway 2 and Lake Chelan are secondary, and the remainder of lynx 

habitat is peripheral. 

Model Description

Source habitat— 

The southernmost extent of the boreal forest supports Canada lynx and overlaps 

with the northeastern Washington assessment area (McKelvey et al. 2000). In 

the contiguous United States, these boreal forests transition into other vegetation 

communities and become more patchily distributed. In North America, the distribution of lynx is nearly coincident with that of snowshoe hares (Bittner and Rongstad 

1982, McCord and Cardoza 1982). Lynx survivorship, productivity, and population dynamics are closely related to snowshoe hare density in all parts of its range 

(USFWS 2005). Quality habitat for lynx occurs where understory stem densities 

and other forest structures provide forage and cover needs of snowshoe hares (Agee 

2000, Hodges 2000, Koehler 1990). Good snowshoe hare habitat has a common denominator—dense, horizontal vegetative cover 3 to 10 ft above the ground or snow 
70

GENERAL TECHNICAL REPORT PNW-GTR-907

level (Hodges 2000). These characteristics include a dense, multilayered understory 

that maximizes cover and browse at both ground level and at varying snow depths 

throughout the winter. Such habitat structure is common in early-seral stages but 

may also occur in coniferous forests with mature but relatively open overstories 

(Hodges 2000).

Primary vegetation that contributes to lynx habitat is lodgepole pine, subalpine 

fir, and Engelmann spruce (Aubry et al. 2000). Habitat selection by Canada lynx 

has been studied on the Okanogan portion of the assessment area. Lynx selected for 

Engelmann spruce and subalpine fir forest, moderate canopy cover, flat to moderate 

slopes, and relatively high elevations; and selected against Douglas-fir and ponderosa pine forests, forest openings, recent burns, sparse canopy and understory, 

and relatively steep slopes (Koehler et al. 2008, Maletzke et al. 2008). Probability 

of use by lynx was 19.4 times greater in spruce and subalpine fir forests than other 

vegetation types, 4.9 times greater in areas with moderate canopy cover than for 

other cover classes, 5.0 times greater at elevations ranging from 5,000 to 6,000 ft 

than other elevations, and 48.8 times greater on flat to moderate slopes than on 

steep slopes (Koehler et al. 2008).

An important component of lynx habitat is areas that are used for denning 

(Moen et al. 2008, Ruediger et al. 2000). The common component of natal den sites 

appears to be large woody debris, either down logs or root wads (Koehler 1990, 

Mowat et al. 2000, Slough 1999, Squires and Laurion 2000, Squires et al. 2008); 

these structures are often associated with late-successional forests. These den sites 

may be located within older regenerating stands (>20 years since disturbance) or 

in mature conifer or mixed-conifer-deciduous (typically spruce/fir or spruce/birch) 

forests (Koehler 1990, Slough 1999). Stand structure appears to be of more importance than forest cover type (Mowat et al. 2000).

To estimate these elements of lynx habitat for this assessment, we mapped both 

early- and late-successional forests within the subalpine fir vegetation zone. Source 

habitat was identified using the following GIS data layers:

• Cover types within the subalpine fir vegetation zone: Engelmann spruce, 

lodgepole pine, Pacific silver fir, and subalpine fir

• Tree size and canopy closure: 1 to 10 in d.b.h. QMD and >50 percent 

canopy closure for early-successional forests, >15 in d.b.h. QMD and >50 

percent canopy closure for late-successional forests 

Grazing— 

Grazing can reduce the density of shrubs that create foraging habitat for snowshoe 

hares (Ruediger et al. 2000), which are the primary prey of the Canada lynx (Aubry 
71

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

et al. 2000, Koehler and Aubry 1994). We categorized the amount of snowshoe hare 

foraging habitat in an active grazing allotment using 10 percent increments from 0 

to 100 percent, with increasing poorer habitat outcomes as the proportion of foraging habitat in an active allotment increased (fig. 15).

Down wood— 

Down wood is an important component of Canada lynx denning habitat (Koehler 

1990, Mowat et al. 2000, Slough 1999, Squires and Laurion 2000, Squires et al. 

2008). To assess the availability of down wood, we intersected lynx source habitat 

with the down wood estimates available from Ohmann and Gregory (2002) using 

the gradient nearest neighbor approach. We categorized the availability of down 

wood within source habitat as follows (fig. 15):

• Low: 10 m3

 (354 ft3) of down wood >20 in 

• Moderate: 10 to 25 m3 (354 to 882 ft3) of down wood >20 in 

• High: >25 m3 (882 ft3) of down wood >20 in 

Winter recreation route density— 

Several researchers have expressed concerns over the effects of winter recreational 

activities on Canada lynx (Bunnell et al. 2006, Buskirk et al. 2000, Koehler and 

Aubry 1994, Kolbe et al. 2007). Specifically, snow compaction associated with 

grooming for snowmobiling and cross-country skiing may provide travel routes for 

Figure 15—Surrogate species assessment model for the Canada lynx.
72

GENERAL TECHNICAL REPORT PNW-GTR-907

competitors and predators such as coyotes, bobcats, and mountain lions (Bunnell et 

al. 2006, Buskirk et al. 2000, Koehler and Aubry 1994). We assessed the influence 

of groomed snow routes on Canada lynx source habitat using existing information 

on the location of groomed and designated routes and using the index described in 

Gaines et al. (2003a). Other groomed routes and snow play areas were known to exist 

but were not available in a digital format. Thus our assessment of the influences of 

winter routes on Canada lynx source habitat likely underestimated the true impacts in 

many of the watersheds. Using the digital data we had on snowmobile trails, we used 

a moving windows analysis with a 0.9-km (2,953-ft) radius circular window (based on 

Gaines et al. 2003a), and categorized these effects as follows (fig. 15):

• Low influence on Canada lynx source habitat <25 percent of source habitat 

with winter route densities <1 mi/mi2

• Moderate influence on Canada lynx source habitat >25 percent of source 

habitat with winter route densities 1 to 2 mi/mi2

• High influence on Canada lynx source habitat >25 percent of source habitat 

with winter route densities >2 mi/mi2

Calculation of historical conditions—

• Source habitat: Departure class 1

• Grazing: 0 percent

• Down wood: Moderate

• Winter recreation route density: Low

The relative sensitivity of watershed index values to variables in the model of 

Canada lynx are shown in table 23.

Table 23—Relative sensitivity 

of watershed index values to 

variables in the model for the 

Canada lynx

Variable Sensitivity rank 

Habitat departure 1

Down wood 2

Grazing 3

Winter recreation 4
73

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Assessment Results

Watershed scores— 

Sixty-two percent (n = 44) of the watersheds had high WI scores (>2.0), 30 percent 

(n = 21) had moderate WI scores (1.0 to 2.0), and 8 percent (n = 6) had low (<1.0) 

WI scores (fig. 16). Departure of source habitat from the historical median across all 

watersheds was the variable that had the greatest influence on the outcomes of the 

WI score (fig. 16). The majority (49 percent, n = 35) were well above their historical 

median levels of source habitat (i.e., >2 class), 28 percent (n = 20) were at or near 

historical levels, and 23 percent were well below their historical median levels of 

source habitat (i.e., < -1 class). 

Watersheds that currently had the greatest amount of source habitat (>10,000 

ac) are the Sinlahekin Creek and Pasayten River. Additionally, the following 

watersheds have 3,000 to 10,000 ac: Mad River, Lost River, Naneum, Lower Lake 

Chelan, Upper Chewuch, Twisp River, Entiat, Middle Methow, Lower Chewuch 

(fig. 16). 

Wisdom et al. (2000) reported similar results for the source habitats in the 

North Cascades and Northern Glaciated Mountains ERUs. In the Northern 

Glaciated Mountains, a strong increase in mid-seral montane forests, along with 

increases in early- and mid-seral subalpine forests accounted for an overall increase 

in source habitat trend. In the North Cascades, increases in early-seral montane and 

subalpine forests were offset by decreases in mid- and late-seral subalpine forests.

Fires are a significant disturbance process in boreal forests of North America, 

and large areas burned throughout Washington during the 19th and 20th centuries 

(Agee 2000). Our assessment accounted for several of these fires; however, the 

148,300-ac Tripod Fire was not accounted for in our vegetation data and burned 

much of the Meadows area in 2006, which had been considered the best and most 

extensive lynx habitat in Washington (Koehler et al. 2008, Stinson 2001).

Twenty-one percent (n = 21) of the watersheds had source habitat with a down 

wood rating of low (<10 m3

/ha [350 ft3/ac] >20 in diameter), 59 percent (n = 42) had 

moderate levels (10 to 25 m3/ha [883 ft3/ac] >20 in diameter), and 20 percent (n = 

14) had high levels of down wood (>25 m3/ha [883 ft3/ac] >20 in diameter).

Based on information that was available on known winter route locations, the 

influence of winter routes on Canada lynx source habitat was rated as low (<25 

percent of source habitat in a watershed with winter route densities <1 mi/mi2) in 

all watersheds. As we discussed earlier, our assessment of the influences of winter 

routes on Canada lynx source habitat likely underestimated the true impacts in 

many of the watersheds owing to data availability.
74

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 16—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for the Canada lynx by watershed in the northeast Washington assessment area.
75

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

We found that most source habitat for Canada lynx was in an active livestock 

grazing allotment. Forty-two percent (n = 30) of the watersheds had <10 percent of 

the source habitat in an active grazing allotment, 11 percent (n = 8) of the watersheds had 10 to 50 percent, and 47 percent (n = 33) had >50 percent of the source 

habitat in an active allotment.

Viability outcome scores— 

The viability outcome scores (VOI) model incorporated the WWI scores (described 

earlier), a habitat distribution index, and a habitat connectivity or permeability index (see pages 29–32 in chapter 1). The WWI scores indicated that the current habitat capability for Canada lynx was 75 percent of its historical capability. Currently, 

68 percent (n = 48) of the watersheds had source habitat amounts >40 percent of the 

historical median. The watersheds with >40 percent were distributed across all of 

the five ecoregions. 

Currently, 7 percent of the assessment area was rated as low permeability, 60 

percent rated as moderate, and 33 percent rated as high. These results are similar 

to the dispersal habitat suitability reported by Singleton et al. (2002) for lynx in the 

same general area. Singleton et al. (2002) identified “fracture zones,” or sizeable 

gaps in dispersal habitat (usually because of low elevations and human development) that occur within the assessment area and warrant careful management attention. These include the upper Columbia-Pend Oreille, southern Okanogan, Stevens 

Pass-Lake Chelan, and Okanogan Valley.

Currently, there is a 64.5 percent probability that the current VOI for the assessment area was B and 25.5 percent probability of outcome C, which indicates that 

suitable environments for the Canada lynx are broadly distributed and of high abundance, but there are gaps where suitable environments were absent or only present 

in low abundance (fig. 17). However, the disjunct areas of suitable environments are 

typically large enough and close enough to each other to permit dispersal among 

subpopulations and to allow the species to potentially interact as a metapopulation. 

Again, exceptions to this may occur along the identified fracture zones. 

Historically, dispersal across the assessment area was assumed to be high. All 

ecoregions and 66 percent (n = 47) of the watersheds contained greater than 40 

percent of the median amount of habitat historically. Historically, there was a 71.2 

percent probability that the viability outcome for Canada lynx was A and a 18.8 

percent probability of a B outcome. This indicates that suitable environments were 

of high abundance and were better connected, allowing for interspecific interactions (fig. 17). We estimated that a reduction in the availability of suitable environments for the Canada lynx likely occurred in the assessment area compared to the 
76

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 17—Current and historical viability outcomes for the Canada lynx in the northeast 

Washington assessment area.

historical distribution and condition of their habitats. In summary, under historical 

conditions, there was a high probability that viable populations of Canada lynx and 

all other species associated with the boreal forest group were well distributed. 

Management Considerations

The following issues were identified during this assessment and from the 

published literature for considerations by managers:

1. Returning disturbance regimes toward the NRV measured at the landscape 

scale would provide Canada lynx habitat components that are distributed 

across the landscape in a sustainable fashion (Agee 2000, Wisdom et al. 2000).

2. Additional information is needed on the location and extent of snowmobile 

routes and snow play areas that we were unable to evaluate owing to lack of 

data. Additional data would help to fully evaluate the effects of these activities on Canada lynx habitat.

3. Fracture zones, or sizeable gaps in dispersal habitat (usually as a result 

of low elevations and human development), occur within the assessment 

area and warrant careful management attention. These include the Upper 

Columbia-Pend Oreille, Southern Okanogan, Stevens Pass-Lake Chelan, 

and Okanogan Valley. 

Returning disturbance 

regimes toward the 

NRV measured at the 

landscape scale would 

provide Canada lynx 

habitat components 

that are distributed 

across the landscape 

in a sustainable 

fashion.
77

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Cassin’s Finch

Introduction

Cassin’s finch is a surrogate species for medium and larger tree forests in the all 

forest communities group. This finch was chosen as a surrogate species primarily 

to represent the risk of grazing that other species in this group share with Cassin’s 

finch. In addition, in contrast to pileated woodpecker and American marten, also 

surrogate species for larger trees, this species is primarily associated with opencanopied forests. Source habitats for this species overlap with species in the dry 

forest group as well. This species is distributed year-round across the assessment 

area and occurs in all the forested communities. 

Model Description

Source habitat— 

Cassin’s finches breed primarily in open, mature coniferous forests of lodgepole and 

ponderosa pine, aspen, supalpine fir, grand fir, and juniper woodlands (Gaines et al. 

2007, 2010a; Gashwiler 1977; Hahn 1996; Huff and Brown 1998; Lehmkuhl et al. 

2007; Schwab et al. 2006; Sullivan et al. 1986). In the Blue Mountains, these finches were negatively associated with habitat variables representing increasing crown 

cover and down woody debris, and were positively associated with canopy height 

(Sallabanks 1995). Gaines et al. (2007) reported that Cassin’s finch abundance was 

positively influenced by thinning and burning restoration treatments within dry forests that retained large trees but reduced canopy closure.

On both the Fremont and Winema National Forests, these finches were more 

abundant in salvage-logged stands where dead and down lodgepole pine were 

removed than in unharvested control stands (Arnett et al. 1997). This research also 

found that the probability of presence of Cassin’s finches was negatively associated 

with the number of live and dead trees, number of live trees <32.8 ft tall, percentage 

of seedling cover, percentage of shrub and grass forb cover, foliage area of live trees, 

and percentage of canopy cover. The probability of presence of Cassin’s finches was 

positively associated with number of trees >11.8 in d.b.h. and the amount of ground 

debris (Arnett et al. 1997). The presence of Cassin’s finches was negatively associated 

with understory vegetation (Hutto 1995a). The more open structure was preferred for 

nesting and allowed them to forage on the ground (Bettinger 2003). 

Hutto (1995a) found Cassin’s finches abundant 1 year postfire in the Rocky 

Mountains, although their numbers dropped off in the second year following fire. 
78

GENERAL TECHNICAL REPORT PNW-GTR-907

This species occupies burned forests as well, though this is usually restricted to 1 

year postfire (Hutto 1995b, Smucker et al. 2005), suggesting that this species may 

be responding to short-term increases in the availability of seeds after wildfire 

(Jewett et al. 1953, Hutto 1995b, Kotliar et al. 2002, Saab and Dudley 1998, 

Sallabanks 1995, Smucker et al. 2005). 

We identified source habitat as:

• Potential vegetation types: Dry, mesic, cold-moist and cold-dry forests

• Cover types: All forested types 

• Tree size: >15 in QMD 

• Canopy closure: <70 percent 

Grazing— 

Saab et al. (1995) summarized the results of five studies that evaluated the effects 

of livestock grazing on Cassin’s finch. Three of the five studies found that Cassin’s 

finches responded negatively to grazing (Page et al. 1978, Schulz and Leininger 

1991, Taylor 1986), one found a neutral effect (Medin and Clary 1991), and one 

found a positive relationship (Mosconi and Hutto 1982). The amount of source 

habitat in an active grazing allotment was categorized using 10 percent increments 

from 0 to 100 percent, with increasing poorer habitat outcomes as the proportion of 

source habitat in an active allotment increased (fig. 18). We calibrated the overall 

negative effect of this risk factor to be relatively small owing to the mixed research 

results.

Historical inputs for focal-species assessment model—

• Departure of source habitat from departure class: Class 1

• Grazing: 0 percent

The relative sensitivity of watershed index values to model variables for the 

Cassin’s finch is shown in table 24.

Assessment Results

Watershed scores— 

Habitat for Cassin’s finch was estimated to be generally well below the historical 

median amount of source habitat in nearly all watersheds (n = 68, 94 percent) 

(fig. 19). The four watersheds that had close to the historical median are the Lower 

Methow River, Ross Lake, Ruby Creek, and Stehekin. These watersheds also had 

the largest amount of current source habitat, as did the Middle Methow River, 

which is departed somewhat more from the historical median (fig. 19). 
79

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 24—Relative sensitivity 

of watershed index values 

to variables in the model for 

Cassin’s finch

Variable Sensitivity rank

Habitat departure 1

Grazing 2

Figure 18—Surrogate species assessment model for the Cassin’s finch.
80

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 19—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for the Cassin’s finch by watershed in the northeast Washington assessment area.
81

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

The area of source habitat in an active grazing allotment was mixed across all 

watersheds: 19 percent (n = 14) were not grazed, 43 percent (n = 32) had 1 to 50 

percent of their source habitat in an active grazing allotment, and 30 percent (n = 

26) had >50 percent of their source habitat in an active grazing allotment.

Owing to the extensive departure in the amount of source habitat from the historical amount in nearly all the watersheds, the WI values were fairly low. Eightysix percent of the WI values were low (<1) (n = 62), 8 percent (n = 6) were moderate 

(>1 and <2), while 6 percent (n = 4) were high (>2) (fig. 19). The four watersheds 

with the highest WI values were those listed above that have departed the least from 

the historical amounts of habitat. The six watersheds that had a medium score (1-2) 

were Lightning Creek, Twisp River, Okanogan River-Bonaparte Creek, Middle 

Methow Creek, Salmon Creek, and Okanogan River-Omak Creek.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. Comparison of the average current WWI for the Cassin’s finch 

to the average historical WWI showed that current conditions are 44 percent of the 

historical capability. Historically, 89 percent (n = 63) of the watersheds contained 

40 percent of the historical median amount of habitat (7,927 ac), while currently 18 

percent (n = 13) had at least that amount. The watersheds with >40 percent were 

distributed across two of the five ecoregions.

The current viability outcomes for the assessment area was C (40 percent) and 

D (60 percent), indicating that suitable environments for the Cassin’s finches are 

frequently isolated or exist at low abundance (fig. 20). It is likely that historical 

conditions would have been characterized as an A outcome (80.8 percent) where 

habitats were broadly distributed and more abundant (fig. 20) than currently. Likely, 

other species in the medium and larger tree forests in the all forest communities 

group may have experienced similar declines in suitable environments and viability.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Decline in the amount of medium-large (>16 in) tree, open-canopy forests 

as source habitat for Cassin’s finches across the assessment area.

2. Nonnative ungulate grazing within the majority of the watersheds within 

the assessment area.

Decline in the amount 

of medium-large (>16 

in) tree, open-canopy 

forests as source 

habitat for Cassin’s 

finches across the 

assessment area.
82

GENERAL TECHNICAL REPORT PNW-GTR-907

Columbia Spotted Frog 

Introduction

Columbia spotted frog populations have declined precipitously across their range 

(e.g., they have been found at only 13 of 59 locations where they were present 

historically in Washington state (McAllister and Leonard 1997). Hayes (1997) 

suggested that Columbia spotted frogs occupied about 10 percent of its original 

range. Small population size and reproductive characteristics likely make Columbia 

spotted frog populations vulnerable to anthropogenic disturbance. The vulnerability 

of Columbia spotted frog populations to residential development at both local and 

regional scales may explain some of the declines seen in this species (Goldberg 

and Waits 2009, Reaser and Pilliod 2005). As a result, Columbia spotted frogs have 

been designated as a sensitive species by the USDA Forest Service, Pacific Northwest Region. They are relatively easy to survey and were found across the northeast 

Washington state assessment area except for high elevations along the western edge 

(Dvornich et al. 1997a). As a surrogate species, they represent species associated 

with the ponds/small lake/backwater group within the riparian family. Their source 

habitat and risk factors cover the other species within this group well where populations overlap. A variety of threats to the persistence of populations of Columbia 

spotted frogs have been identified, including wetland loss, introduced predators, 

mining, grazing, development, and diseases (Pearl et al. 2007a, Monello and Wright 

1999, Reaser and Pilliod 2005, USDI Fish and Wildlife Service 1997a). Columbia 

spotted frogs are year-round residents of the assessment area (Reaser and Pilliod 

2005); this assessment was for breeding and rearing habitat.

Figure 20—Current and historical viability outcomes for the Cassin’s finch in the northeast Washington 

assessment area.
83

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Model Description

Source habitat— 

Columbia spotted frogs are highly dependent on aquatic habitats and require permanent and semipermanent wetlands that have aquatic vegetation and some deeper or flowing water for overwintering (Bull and Marx 2002, Pilliod et al. 2002). 

Breeding habitat for Columbia spotted frogs has been characterized, in general, 

as small silt or muck bottom ponds with emergent vegetation (Morris and Tanner 

1969, Pearl et al. 2007b, Pilliod et al. 2002, Welch and MacMahon 2005). Wintering 

habitat was described as large (about 5 ac), deep (>10 ft) ponds and lakes (Bull and 

Hayes 2002, Pilliod et al. 2002). Munger et al. (1998) more specifically characterized the habitat associations of adult spotted frogs as still waters with associated 

shrublands and riverine conditions. They identified these areas as having National 

Wetland Inventory (NWI) classifications (Cowardin et al. 1979) associated with 

scrub-shrub and seasonally flooded wetlands. Presence of spotted frogs was negatively associated with areas classified with emergent vegetation and temporarily 

flooded. Specifically, adult spotted frogs were found more often than expected in 

palustrine, scrub-shrub, seasonally flooded (PSSC) wetlands and intermittent riverine, streambed, seasonally flooded (R4SBC) wetlands and less often than expected 

in palustrine, emergent, seasonally flooded (PEMC) wetlands and intermittent riverine, streambed, temporarily flooded (R4SBA) areas. Bull and Hayes (2001) also 

found adult Columbia spotted frogs associated with riverine habitats in the summer 

(<40 in deep, cobble substrate, without aquatic vegetation).

For this analysis, source habitat was considered to be PSSC and R4SBC, as 

described in the NWI (Cowardin et al. 1979) (fig. 21).

The current habitat departure for Columbia spotted frogs was set at -2 for all 

watersheds (see p. 19).

Invasive animals— 

Introduced fish have been linked to the decline of ranid frog species in general 

across western North America (Hayes and Jennings 1986) and specifically to declines of Columbia spotted frogs (Monello and Wright 1999, Reaser 2000). The 

negative effects of fish introduced into previously fishless ponds and lakes were 

considerable for amphibians that required permanent water bodies for reproduction and overwintering (Knapp et al. 2001, 2003, 2005). These negative effects 

also extended to stream habitats with introduced salmonids (Bosch et al. 2006). 

Previously fishless lakes with introduced trout (Oncorhynchus spp.) populations had 

lower abundance and recruitment of spotted frogs than fishless lakes (Hirner and 

Cox 2007, Pilliod and Peterson 2001). However, Bull and Marx (2002) did not find 
84

GENERAL TECHNICAL REPORT PNW-GTR-907

a strong relationship between the presence of introduced trout and the abundance of 

eggs and larvae of Columbia spotted frogs.

The following classes were used to evaluate the effect of introduced trout on 

Columbia spotted frogs (fig. 21):

• High: Introduced trout present in ≥50 percent of source habitat within a 

watershed

• Low: Introduced trout present in <50 percent of source habitat within a 

watershed

• Zero: Introduced trout not present in source habitat within a watershed

Grazing— 

The results reported in the literature on the effects of grazing on Columbia spotted frogs were equivocal. Reaser (2000) found that cattle grazing was related to 

low recruitment and high mortality. These findings were supported by other studies 

(Cuellar 1994, Ross et al. 1999, Worthing 1993). Conversely, others (Adams et al. 

Figure 21—Surrogate species assessment model for Columbia spotted frog.
85

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

2009, Bull and Hayes 2000) reported no differences in productivity of spotted frogs 

on grazed vs. ungrazed sites in northeast Oregon. However, there was an indication that grazed sites in northeast Oregon had reduced food abundance (Bull 2003a, 

Whitaker et al. 1983). Also, overgrazing could negatively affect reproduction if egg 

masses or recently metamorphosed frogs were directly trampled or if banks were 

collapsed along ponds or rivers that serve as overwintering sites (Bull 2005).

The impact of grazing on source habitat within a watershed was based on the 

percentage of source habitat in that watershed with an active cattle grazing allotment (i.e., sheep grazing allotments were not considered) (fig. 21). The amount 

of source habitat in an active grazing allotment was categorized using 10 percent 

increments from 0 to 100 percent, with the assumption that habitat outcomes 

became increasingly poorer as the proportion of source habitat in an active allotment increased.

Pond size— 

Ponds reported used for breeding and during the summer ranged in mean size from 

0.06 to 0.98 ac (Bull and Hayes 2001, Pilliod et al. 2002). Ponds used over winter 

ranged in mean size from 0.2 to 4.9 ac (Bull and Hayes 2002, Pilliod et al. 2002). 

Bull and Marx (2002) found that lake size was a significant factor in the prediction of 

the abundance of egg masses. Lakes evaluated in that study ranged in size from 0.98 

to 86.0 ac. A negative relationship was found between productivity and lake size.

The following classes were used to evaluate the effect of pond and lake size on 

Columbia spotted frogs (fig. 21):

• Less than optimum: <0.062 or >4.9 ac mean size within a watershed

• Optimum: 0.062 to 4.9 ac mean size within a watershed

Road density— 

Increasing densities of roads is expected to result in reductions of habitat quality for Columbia spotted frogs because of direct mortality, habitat fragmentation, 

and reduced water quality (Findlay and Houlahan 1997, Findlay and Bourdages 

2000, Funk et al. 2005, Houlahan and Findlay 2003, Trombulak and Frissell 2000, 

Vos and Chardon 1998). Habitat fragmentation and associated reduction in connectivity of habitat has been associated with the disappearance of frog populations 

from occupied habitat (Cushman 2006, Knapp et al. 2003). Columbia spotted frogs 

have been reported to move from 1,640 ft (Bull and Hayes 2001, Hollenbeck 1974, 

Turner 1960) to 3,280 ft (Pilliod et al. 2002) between ponds. Therefore, the effects 

of roads were assumed to occur within 3,280 ft of source habitat.

The following density classes were based partially on the findings of Findlay 

and Houlahan (1997) and were applied to an area within 3,280 ft of source habitat 

within a watershed (fig. 21):
86

GENERAL TECHNICAL REPORT PNW-GTR-907

• Zero: <0.1 mi/mi2 open roads

• Low: 0.1 to 1.0 mi/mi2 open roads 

• Moderate: 1.1 to 2.0 mi/mi2 open roads

• High: >2.0 mi/mi2 open roads

Variables considered but not included— 

American bullfrogs (Rana catesbeiana) have been reported to be a factor in the 

decline of populations of ranid frogs (e.g., Doubledee et al. 2003) and may be associated with declines in spotted frog populations (Bull 2005, Monello et al. 2006). 

However, there was limited empirical evidence to implicate American bullfrogs as 

a cause of spotted frog population reduction or loss. There was also limited spatial 

data on the distribution of American bullfrogs across the assessment area. Because 

of these factors, we did not include potential effects of American bullfrogs on spotted frogs in this model.

Mining activities may affect wetlands and their biota directly through habitat 

destruction or runoff of sediments and contaminants generated during mining 

operations (Linder et al. 1991). Anecdotal evidence has indicated that mining 

operations may negatively affect habitat for spotted frogs. However, these effects 

have not been documented. Also, digital spatial information concerning locations of 

mining operations throughout the assessment area was generally unavailable. As a 

result, we did not include this variable in our assessment.

Calculation of historical conditions— 

Values of the model variables were set with the following values to estimate 

historical habitat conditions:

• Current amount of habitat in each watershed was increased by 30 percent

• Departure of source habitat from HR: 0.5

• Invasive animals: Class zero

• Grazing: None

• Pond size: Same as current condition

• Road density: Class zero

GIS databases use—

• National Wetland Inventory

• Active cattle grazing allotments

• Lakes

• Roads

The relative sensitivity of WI values to variables in the model for Columbia 

spotted frog is shown in table 25.
87

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Assessment Results

Watershed scores— 

Major factors that influenced the WI scores included the amount of source habitat 

compared to levels historically available in the watersheds (fig. 22). We assumed 

that all watersheds had approximately 70 percent of the historical amount of habitat 

remaining based on the findings of Dahl (1990) and Peters (1990). Watersheds that 

currently have the greatest amount of source habitat included Chewelah, Stensgar/

Stranger, Upper Little Spokane River, Upper Okanogan River, and Upper Pend 

Oreille (fig. 22). However, within all of these watersheds <25 percent of the source 

habitat was managed by federal agencies. The watersheds with the least amount of 

source habitat were located across the western portion of the assessment area.

Historically, 65 of 72 (90 percent) watersheds within the assessment area provided habitat for Columbia spotted frogs (fig. 22). However, 25 of those watersheds 

provided less than the historical median amount of habitat across all watersheds 

with habitat in the assessment area (fig. 22). This analysis indicated that 8 percent 

(n = 6) of watersheds with source habitat currently have high WI scores (>2.0) 

(fig. 22). The majority of watersheds (82 percent, n = 59) have WI scores that were 

moderate (>1.0 to <2.0). These were distributed across the assessment area.

The size of wetlands affected suitability of habitat for Columbia spotted frogs. 

Mean size of ponds and wetlands within watersheds ranged from <0.25 to >124 ac. 

The mean sizes of habitats within 31 percent of the watersheds (n = 22) were within 

the optimum range.

Grazing affected suitability of habitat for Columbia spotted frogs in 43 percent 

of the watersheds (n = 31) (Reaser 2000). Percentage of source habitat grazed was 

highest in the northern and central portions of the assessment area.

Table 25—Relative sensitivity of

watershed index values to variables 

in the model for Columbia spotted 

frogs

Variable Sensitivity rank

Habitat departure 1

Pond size 2

Grazing impact 3

Invasive animals 4

Road density 5

Grazing affected 

suitability of habitat for 

Columbia spotted frogs 

in 43 percent of the 

watersheds (n = 31).
88

GENERAL TECHNICAL REPORT PNW-GTR-907

Road density also affected suitability of watersheds as habitat for Columbia 

spotted frogs (Trombulak and Frissell 2000). The percentage of source habitat with 

high road densities generally increased from the northeast to the southwest portion 

of the assessment area with low densities of roads dominating in the northwest.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability 

Figure 22—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D) habitat 

condition class for Columbia spotted frogs (CSF) by watershed in the northeast Washington assessment area (NEWA).
89

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

for Columbia spotted frogs within the assessment area was 56 percent of the 

historical capability. Dispersal across the assessment area was not considered an 

issue for Columbia spotted frogs. Four of five ecoregions currently contained ≥1 

watershed with >40 percent of the median amount of historical source habitat (the 

median was calculated across all watersheds with source habitat). Forty watersheds 

(56 percent) had >40 percent of the median amount of historical source habitat. 

Under those circumstances, there was a 72 percent probability that the current viability outcome for Columbia spotted frogs was C (fig. 23). It was likely that all 

other species included in the ponds/small lake/backwater group within the riparian 

family had similar outcomes.

Historically, dispersal across the assessment area was not considered an issue 

for Columbia spotted frogs. All ecoregions contained at least one watershed with 

>40 percent of the median amount of historical source habitat. Sixty-four percent 

(n = 46) of the watersheds had >40 percent of the median amount of historical 

source habitat. Under those circumstances, there was a 71 percent probability that 

the historical viability outcome for Columbia spotted frogs was A (fig. 23).

Historically, Columbia spotted frogs and other species in the ponds/small lake/

backwater group within the riparian family were likely well distributed with viable 

populations across the assessment area. Changes in habitat conditions have resulted 

in the current situation where these species are likely well distributed in only a 

portion of the assessment area.

Figure 23—Current and historical viability outcome for Columbia spotted frogs in the northeast Washington 

assessment area.
90

GENERAL TECHNICAL REPORT PNW-GTR-907

Management Considerations

The following issues were identified for species in the ponds/small lake/backwater 

group within the riparian family during this assessment and from the published 

literature for considerations for managers:

1. Reduction of suitable wetland source habitats.

2. Negative effects of roads adjacent to source habitats.

3. Negative effects of introduced fish.

4. Degradation of source habitats by domestic livestock.

Eared Grebe

Introduction

Eared grebes were chosen as a surrogate species to represent species associated 

with the marsh/open water group in the wetland family. The main risk factors for 

all species associated with marsh habitat were draining, filling, and degradation of 

marshes; environmental contaminants; and disturbance. Eared grebes were chosen 

as the surrogate species for this group because they had widespread distribution 

in eastern Washington, their risk factors included those of the other species in this 

group, and they were not a hunted species. Habitats for eared grebes and other 

species in this group were not abundant on National Forest System lands in eastern 

Washington state, and they were patchily distributed across the northeast Washington assessment area with concentrations in the central and eastern portions (Smith 

et al. 1997). Eared grebes were breeding season residents of the assessment area 

(Cullen et al. 1999); this assessment was for breeding and rearing habitat.

Model Description

Source habitat— 

Large, very open (i.e., 70 percent open water) wetlands, ponds, and lakes <9.8 ft 

deep were preferred colony sites for eared grebes (Boe 1992, Faaborg 1976, Savard 

et al. 1994). Boe (1992) went on to report that type 4 wetlands were preferred and 

type 5 wetlands were avoided. Kantrud and Stewart (1984) reported that 54 percent 

of eared grebe colonies were in seasonal wetlands, 36 percent in semipermanent 

wetlands, and 11 percent in permanent wetlands (n = 35). Naugle et al. (1999) and 

Savard et al. (1994) also noted that eared grebes avoided wetlands, ponds, and lakes 

with woody vegetation at the edges. These findings suggested that palustrine, emergent wetlands (PEM), as described in the NWI (Cowardin et al. 1979) with adjacent 

open water were preferred habitat for nesting eared grebes. We delineated habitat 
91

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

for this analysis by identifying all PEMs from NWI maps and adding a 1,640-ft 

buffer into adjacent open water, where it was present. Habitat below 5,900-ft 

elevation was considered as source habitat. Habitat above that elevation was not 

available for nesting in the spring because of persistent ice.

Eared grebes also used open water lakes with submergent vegetation, which 

was used as a base for nest building (Boe 1993). However, this condition was not 

characterized in the NWI maps so we did not include it in our description of source 

habitat. Also, although wetlands may have been created with development of reservoirs within the assessment area, wetlands were also inundated as reservoirs were 

filled (Yokom et al. 1958). Information was not available on the resulting net loss or 

gain, so this aspect was not addressed in these applications of the model.

The current habitat departure for eared grebes was set at -2 for all watersheds 

(see p. 21).

Pond/lake size— 

Eared grebes require a long, running takeoff to take flight so they prefer large,

very open ponds and lakes (Faaborg 1976, Johnsgard 1987). Increasing area of wetland was strongly related to suitability of a site for eared grebes (Naugle et al. 2001, 

Yokom et al. 1958). Ponds and lakes >75 ac were preferred (Boe 1992) although 

smaller water bodies (e.g., 50 ac) also were used (Faaborg 1976). Colony size was 

positively correlated with wetland size, and larger wetlands tended to be used more 

often in subsequent years than smaller wetlands (Boe 1992). We also assumed that 

the probability of a disturbance effect from human recreation activity was lower on 

large water bodies than on small water bodies. The following classes were used to 

evaluate the effect of habitat size on habitat quality (fig. 24):

• Small: <50 ac mean size within a watershed

• Medium: 50 to 75 ac mean size within a watershed

• Large: >75 ac mean size within a watershed

Emergent plant:open water ratio— 

Access to open water was important for eared grebes because they move to open 

water when disturbed from their nests, and because they need a running start before 

taking flight (Boe 1992). The source habitat complex of wetland and open water 

with ≥50 percent open water was considered in this analysis to be higher quality 

habitat than wetlands with <50 percent open water. The following classes were used 

to evaluate the effect of emergent plant:open water ratio on habitat quality (fig. 24):
92

GENERAL TECHNICAL REPORT PNW-GTR-907

• Low: <50 percent open water mean size in wetland complexes within a 

watershed

• High: ≥50 percent open water mean size in wetland complexes within a 

watershed

Invasive animals— 

Grass carp and common carp have been documented to have detrimental effects 

on aquatic vegetation in lakes and wetlands through uprooting of plants, increased 

herbivory, and decreased water quality resulting in a decrease in habitat quality 

for waterfowl (Bonar et al. 2002, Crivelli 1983, Fletcher et al. 1985, Roberts et al. 

1995). The presence of carp in lakes and wetlands identified as source habitat for 

eared grebes was assumed to result in lower habitat quality.

The impact of carp on the quality of source habitat within a watershed was 

based on the percentage of source habitat in that watershed with carp present. 

The amount of source habitat with carp present was categorized using 10 percent 

increments from 0 to 100 percent, with increasing poorer habitat outcomes as the 

Figure 24—Surrogate species assessment model for eared grebe.
93

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

proportion of source habitat with carp increased (fig. 24). We used information 

from WDFW (2005) on fish surveys for this analysis to evaluate the likelihood of 

the presence of carp in source habitats in the assessment area.

Recreation sites— 

Presence of boat-launch ramps and campgrounds on lakes and ponds was expected 

to result in reductions of habitat quality for eared grebes because of an increased 

potential for human disturbance and habitat fragmentation (Boe 1992, Hanus et 

al. 2002). Potential adverse effects include egg and nestling mortality, premature 

fledging or nest evacuation, and reduced body mass, or slower growth of nestlings 

(Rogers and Smith 1995, Skagen et al. 2001). Adult behavior also may be altered by 

disturbance, resulting in altered foraging patterns. Use of motorized watercraft near 

nests of eared grebes may result in increased disturbance, but the published literature 

was equivocal on this aspect (Rogers and Smith 1995, Titus and VanDruff 1981).

The impact of human disturbance on the quality of source habitat within a 

watershed was based on the percentage of source habitat in that watershed with 

associated recreation sites. The amount of source habitat associated with recreation 

sites was categorized using 10 percent increments from 0 to 100 percent, with 

increasing poorer habitat outcomes as the proportion of source habitat associated 

recreation sites increased (fig. 24).

GIS databases used—

• National Wetland Inventory

• Lakes

• Recreation sites

• Carp survey data

Calculation of historical conditions— 

Values of the model variables were set with the following values to estimate historical habitat conditions:

• Current amount of habitat in each watershed was increased by 30 percent

• Departure of source habitat from HRV: 0.5

• Pond/lake size: Same as current condition

• Emergent plant: Open water ratio—Same as current condition 

• Invasive animals: 0 percent of source habitat affected

• Recreation sites: 0 percent of source habitat affected

The relative sensitivity of WI values to variables in the model for eared grebe 

are shown in table 26.
94

GENERAL TECHNICAL REPORT PNW-GTR-907

Assessment Results

Watershed scores— 

Historically, 21 percent (n = 15) of the watersheds within the assessment area 

provided habitat for eared grebes. Currently, the same watersheds contained some 

habitat for eared grebes, although three had minimal amounts (i.e., <50 ac) (fig. 25). 

Watersheds with the largest amounts of habitat were located in the central, eastern, and southern portions of the assessment area. We assumed all watersheds had 

reductions in amount of habitat when compared to historical conditions (fig. 25). All 

watersheds with habitat had low WI scores (i.e., <1.0) (fig. 25).

Large wetlands were assumed to be higher quality habitat than small wetlands 

(Boe 1992). Thirteen of the 15 watersheds with source habitat had large mean sizes 

of wetland habitat; two had medium mean size of habitat. The emergent plant:open 

water ratio was high for all watersheds but one. The presence of carp in lakes and 

wetlands identified as source habitat for eared grebes was assumed to result in 

lower habitat quality; carp were assumed to be present in all source habitats. Presence of boat-launch ramps on lakes and ponds was expected to result in reductions 

of habitat quality for eared grebes (Boe 1992, Hanus et al. 2002). Within the 10 

watersheds with boat launches associated with source habitat for eared grebes, >80 

percent of the habitat was accessible to boats.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability for 

eared grebe within the assessment area was 12 percent of the historical capability. 

Dispersal across the assessment area was not considered an issue for this species. 

Four of five ecoregions currently contained at least one watershed with >40 percent 

Table 26—Relative sensitivity of

watershed index values to variables in the model for eared grebes

Variable Sensitivity rank

Habitat departure 1

Human disturbance 2

Pond/lake size 3

Invasive effect 4

Open water: 

wetland ratio 5
95

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

of the median amount of historical source habitat (median was calculated across all 

watersheds with source habitat). Fourteen percent (n = 10) of the watersheds had 

>40 percent of the median amount of historical source habitat. Under those circumstances, there was a 72 percent probability that the current viability outcome for 

Figure 25—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D)

habitat condition class, for the eared grebe (EAGR) by watershed in the northeast Washington assessment area (NEWA).
96

GENERAL TECHNICAL REPORT PNW-GTR-907

eared grebe with the marsh/open water group in the wetland family was E, indicating that suitable habitat was highly isolated and in very low abundance (fig. 26). It is 

likely that other species associated with the marsh/open water group in the wetland 

family had similar outcomes.

Historically, dispersal across the assessment area was not considered an issue 

for this species. All ecoregions contained at least one watershed with >40 percent 

of the median amount of historical source habitat (median was calculated across all 

watersheds with source habitat). Fifteen percent (n = 11) of watersheds had >40 percent of the median amount of historical source habitat. Under those circumstances, 

there was a 47 percent probability that the historical viability outcome for eared 

grebe was C and a 33 percent probability that the historical viability outcome for 

these species was D, indicating that this habitat had a patchy to isolated distribution 

and existed at low abundance (fig. 26).

Under historical conditions, eared grebes and other species associated with 

the marsh/open water group in the wetland family were likely well distributed in 

only a portion of the assessment area or were not well distributed throughout the 

assessment area. However, currently they are likely to face extirpations throughout 

the assessment area owing to loss of habitat and limited distribution of suitable 

environments.

Figure 26—Current and historical viability outcomes for eared grebes in the northeast Washington assessment area.

Suitable habitat was 

highly isolated and in 

very low abundance. 

It is likely that other 

species associated 

with the marsh/open 

water group in the 

wetland family had 

similar outcomes.
97

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Management Considerations

The following issues were identified during this assessment and from the published 

literature for species associated with the marsh/open water group in the wetland 

family for consideration by managers:

1. Loss and degradation of wetland habitats.

2. Negative effects of carp invasion in source habitats.

3. Negative effects of disturbance from water-based recreation.

Fox Sparrow 

Introduction

Fox sparrows were chosen as a surrogate species to represent species in the earlysuccessional group of the open forest family. They preferred dense, low shrub 

growth typical of such habitats and were susceptible to the effects of grazing by 

domestic livestock similar to other species in this group. The range of fox sparrows 

includes the western and eastern portions of the assessment area (Smith et al. 1997). 

Fox sparrows are breeding season residents of the assessment area (Weckstein et al. 

2002); this assessment is for breeding and rearing habitat.

Model Description

Source habitat— 

Fox sparrows were strongly associated with riparian shrubs (e.g., willow [Salix

spp.], alder [Alnus spp.]) (Webster 1975), and the shrub stage of succession following fire and clearcut logging in mature forests (Banks 1970, Fontaine et al. 2009, 

Hagar 1960, Kirk and Hobson 2001, Machtans and Latour 2003, Simon et al. 2002, 

Weckstein et al. 2002). Densities of fox sparrows were reported highest in stands 

with heavy salvage logging following fire, intermediate in moderately salvaged 

stands, and lowest in the unsalvaged stands (Cahall and Hayes 2009). Although 

the early stages of the shrub successional stage were preferred (e.g., 3 to 15 years) 

(Hagar 1960, Meslow and Wight 1975), they also used shrub habitats for up to 30 

years after disturbance (Simon et al. 2002). Residual trees remaining after clearcut 

logging (especially conifers) resulted in reduced densities of fox sparrows (Simon 

et al. 2002).

Abundance of fox sparrows was significantly correlated with mean shrub height 

(Anderson 2007, Olechnowski and Debinski 2008). Tall shrubs without tree cover 

were preferred, and tall shrubs with residual tree cover were used, but to a lesser 

extent. Densities of fox sparrows (r = 0.80) were positively correlated with shrub 

volume (Cahall and Hayes 2009). Cover types representing montane shrubs and 
98

GENERAL TECHNICAL REPORT PNW-GTR-907

forest reinitiation and regeneration following timber harvest and fire were included 

as source habitats (fig. 27). This included single- and multistory forested stands in 

mesic forest, cold-dry forest, cold-moist forest, and parkland potential vegetation 

conditions (nonforest and dry forest were not included) with <30 percent canopy 

cover or tree size <4 in QMD. Shrub-steppe (i.e., arid shrub) land cover classes 

were not included.

• Vegetation zones: Western hemlock, Pacific silver fir, mountain hemlock, 

subalpine fir, parkland

• Cover type: Conifer mix, Douglas-fir, Engelmann spruce, grand fir, 

lodgepole pine, mountain hemlock, Pacific silver fir, parkland, riparian 

and deciduous, montane shrubs, western hemlock, western larch, western 

redcedar

• Size class: <4 in QMD 

• Tree layers: Single and multistoried

Figure 27—Surrogate species assessment model for fox sparrow.
99

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Grazing— 

The results reported in the literature on the effects of grazing on fox sparrows were 

unequivocal. Several studies reported a negative response from fox sparrows associated with cattle grazing (Knopf et al. 1988, Page et al. 1978, Schulz and Leininger 

1991). Although fox sparrows were parasitized by brown-headed cowbirds (which 

were often associated with livestock grazing operations), it occurred infrequently 

(Friedmann 1963).

The impact of grazing on source habitat within a watershed was based on the 

percentage of source habitat in that watershed within an active grazing allotment. 

The amount of source habitat in an active grazing allotment was categorized using 

10 percent increments from 0 to 100 percent, with increasing poorer habitat outcomes as the proportion of source habitat in an active allotment increased (fig. 27).

Shrub cover— 

The amount of shrub cover was directly related to habitat quality for fox sparrow. 

Low shrub cover greatly diminishes the value of an area as habitat for fox sparrows. 

High shrub cover greatly increases the quality of habitat for fox sparrows. Fires 

tend to eliminate shrub cover and reduce habitat quality for fox sparrow in the short 

term (Samuels et al. 2005). This variable addressed the proportion of source habitat that had >70 percent shrub cover as determined from gradient nearest-neighbor 

analysis (Ohmann and Gregory 2002) (fig. 27).

Calculation of historical conditions— 

Values of the model variables were set with the following values to estimate 

historical habitat conditions:

• Departure of source habitat from HRV: 0.5

• Grazing: None

• Shrub cover: Percentage of shrubs was set at 50 percent 

The relative sensitivity of watershed index values to variables in the model for 

fox sparrow are shown in table 27.

Assessment Results

Watershed scores— 

Historically, all 73 watersheds within the assessment area provided habitat for fox 

sparrows. Currently, 92 percent (n = 67) of the watersheds contain some habitat for 

fox sparrows, although several have minimal amounts (i.e., <50 ac) (fig. 28). All 

watersheds with habitat had low WI scores (i.e., <1.0) (fig. 28).
100

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 27—Relative sensitivity

of watershed index values to 

variables in the model for fox 

sparrows

Variable Sensitivity rank

Shrub cover 1

Habitat departure 2

Grazing impact 3

Figure 28—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and 

(D) habitat condition class for fox sparrows (FDSP) by watershed in the northeast Washington assessment area 

(NEWA).
101

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Factors that influenced the WI scores included the amount of source habitat 

compared to levels historically available in the watersheds. All but one of the 

watersheds were well below their historical median levels of source habitat (i.e., 

class -4.0). The upper Chewuch River watershed was above its historical median 

levels (>4.0) (fig. 28).

The percentage of source habitat within an active grazing allotment was used 

to assess the impact of grazing to fox sparrows and ranged from 0 to 100 percent 

by watershed. Source habitat within 20 percent (n = 14) of the watersheds was not 

grazed. Twenty-four percent (n = 17) of the watersheds had <25 percent of source 

habitat grazed; 13 percent (n = 9) had 25 to 50 percent grazed; 11 percent (n = 8) 

had 50 to 75 percent grazed; and 32 percent (n = 23) had >75 percent grazed.

The amount of shrub cover was directly related to habitat quality for fox sparrow (Samuels et al. 2005). The percentage of source habitat with >70 percent shrub 

cover varied from 0 to 40 percent among watersheds. Seventeen percent (n = 12) 

of the watersheds had <1.0 percent, 57 percent (n = 41) of the watersheds had 1 

to 10 percent, 21 percent (n = 15) had 10 to 20 percent and 5 percent (n = 3) had 

>20 percent.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat distribution index. The WWI scores indicated that the current habitat capability for fox 

sparrows within the assessment area was only 9 percent of the historical capability. 

Dispersal across the assessment area was not considered an issue for this species. 

One of five ecoregions currently contained at least one watershed with >40 percent 

of the median amount of historical source habitat (median was calculated across 

all watersheds with source habitat). One watershed had >40 percent of the median 

amount of historical source habitat (1 percent). Under those circumstances, there 

was an 80 percent probability that the current viability outcome for fox sparrow was 

E with the remaining in D (20 percent), indicating that habitat for these species was 

highly isolated and at very low abundance (fig. 29). Outcomes were likely similar 

for other species in the early-successional group of the open forest family.

Historically, dispersal across the assessment area was not considered an issue 

for this species. All ecoregions contained at least one watershed with >40 percent 

of the median amount of historical source habitat (median was calculated across all 

watersheds with source habitat). Ninety-five percent (n = 69) of the watersheds had 

>40 percent of the median amount of historical source habitat. Under those circumstances, there was a 85.5 percent probability that the historical viability outcome 

for fox sparrow was A, indicating that habitat was broadly distributed and in high 

abundance (fig. 29).
102

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 29—Current and historical viability outcomes for fox sparrows in the northeast Washington assessment area.

In summary, under historical conditions, fox sparrows and other species in 

the early-successional group of the open forest family were likely well distributed 

throughout the assessment area; currently they were likely not well distributed and 

at risk of extirpation.

Our results for this species were similar to those reported in the broad-scale 

habitat analysis by Wisdom et al. (2000) in ICBEMP. According to the ICBEMP, 

terrestrial vertebrate habitat analyses, historical source habitats for Lazuli bunting, 

which was associated with source habitats similar to those used by fox sparrows, 

included portions of the Northern Cascades and the Northern Glaciated Mountains 

ERUs, which overlap our assessment area (Wisdom et al. 2000). Within this historical habitat, declines in source habitats for this species have been extensive, -100 

percent in the Northern Cascades and -66 percent in the Northern Glaciated Mountains according to Wisdom et al. (2000).

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Reduction of early-seral habitats, primarily those resulting from fire 

(Simon et al. 2002).

2. Negative effects of grazing in source habitats.
103

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Golden Eagle

Introduction

Golden eagles were chosen as a surrogate species to represent species of concern 

associated with the woodland/grass/shrub group in the woodland/grass/shrub family. This species reflected the risk of human disturbance that affected other species 

in these habitats. It was also associated with cliff structures that were not normally 

used by other surrogate species within this group and family. Golden eagle nests 

are readily monitored and are often surveyed by other public agencies and nongovernmental groups, so trend data may be readily available. Golden eagles range 

throughout the assessment area except for the eastern portion (Smith et al. 1997). 

Golden eagles are year-round residents of the assessment area (Kochert et al. 2002); 

this assessment was for nesting and rearing habitat.

Model Description

Source habitat— 

The fundamental requirements of suitable habitat for golden eagles included 

(1) sources of food, (2) adequate nesting sites, and (3) limited human intrusion 

(Beecham and Kochert 1975, Thelander 1974). Golden eagle habitats with the highest population density were characterized by availability of diverse and numerous 

prey, and abundant nest sites (Phillips et al. 1984). Areas with low population densities had few nest sites available for use and were fragmented by cropland.

Nesting habitat— 

Availability of adequate nest sites may limit distribution of golden eagles, especially in sagebrush and grassland habitats (Beecham and Kochert 1975, Carrete et 

al. 2000, Phillips and Beske 1990). Throughout North America, golden eagles nest 

primarily on cliffs (McGahan 1968, Mosher and White 1976, Smith and Murphy 

1982). Generally, trees were used infrequently as nest substrates but may be important in local areas (Menkens and Anderson 1983).

Forests—

Nests in trees have been reported in northeast and north-central Wyoming 

(Menkens and Anderson 1987, Phillips and Beske 1990, Phillips et al. 1990), the 

central and north Coast Range in California (Chinnici et al. 2007, Hunt et al. 1999), 

and coastal Washington (Bruce et al. 1982, Eaton 1976). Wide varieties of trees 

were used as nest sites throughout their range (Kochert et al. 2002). Tree species throughout eastern Oregon and Washington that were most likely to provide 

nest sites include ponderosa pine (Pinus ponderosa) (MacLaren 1986, Phillips and 
104

GENERAL TECHNICAL REPORT PNW-GTR-907

Beske 1990, Phillips et al. 1990), Douglas-fir (Pseudotsuga menziesii) (McGahan 

1968), and cottonwood (Populus spp.) (Bates and Moretti 1994). However, a preference has been reported for large ponderosa pines over cottonwoods (Phillips and 

Beske 1990). The nest tree was usually the largest or one of the largest trees in a 

stand (Menkens and Anderson 1987), was isolated or on the fringe of a small stand 

of trees (Baglien 1975), and was <1,640 ft from open areas (Bruce et al. 1982). 

Dense forest stands were avoided as nest sites (Phillips and Beske 1990, Phillips et 

al. 1984, Whitfield et al. 2004). Large trees may have been selected to ensure nest 

stability and longevity, and placement in the upper portion of tall trees may have 

improved accessibility (Menkens and Anderson 1987).

Forested source habitat for nesting golden eagles for this analysis was assumed 

to be large trees (>20 QMD), single- and multistory, open (<50 percent canopy 

closure) ponderosa pine or Douglas-fir, <1,640 ft from an edge with low-elevation 

shrub or grassland cover types with an elevation of <3,600 ft. The amount of habitat 

in each watershed was compared to the current median value across watersheds 

with habitat (fig. 30).

Cliffs—

Many nests located on cliffs had a wide view of the surrounding area (Beecham 

1970) or were on prominent escarpments (Bates and Moretti 1994). Proximity to 

hunting grounds was an important factor in nest-site selection (Camenzind 1969, 

McIntyre et al. 2006). In northern areas, weather conditions at the beginning of 

nesting season were a critical factor in choice of nest site location (Morneau et al. 

1994). Average annual snowfall may have limited distribution of nest sites; in southwest Montana, nests were usually built in areas receiving <200 in of snow (Baglien 

1975). Cliff nests were built on several rock substrates including sandstone, shale, 

granite gneiss, limestone, basalt, and granite (Schmalzried 1976). Loosely cemented materials such as breccias, conglomerates, or agglomerate sluff were avoided 

(Baglien 1975). At four study areas, the mean height of cliffs with nests was 116.5 

ft; mean height of nests on the cliff was 67.9 ft (Kochert et al. 2002).

Cliff source habitat for nesting golden eagles for this analysis was assumed to 

be cliffs >50 ft high at <3,500-ft elevation (to eliminate areas with persistent spring 

snowpacks). To model the availability of cliff source habitat, a digital elevation 

model was used to identify cliff structures (similar to López-López et al. 2007) that 

were >5 ac to distinguish the prominent cliffs structures from the smaller cliffs that 

were unlikely to provide nesting habitat. The following classes were used to characterize watersheds for cliff nesting habitat (fig. 30):
105

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

• Zero: Potential nesting habitat does not occur within a watershed

• Low: <10 ac of potential nesting habitat within a watershed

• Moderate: Less than median amount across all watersheds of potential nesting habitat within a watershed

• High: Less than median amount across all watersheds of potential nesting 

habitat within a watershed

Foraging habitat— 

Amount and density of prey had a direct effect on distribution, reproductive rates, 

and population size of golden eagles (Bates and Moretti 1994, Martin et al. 2009, 

Pedrini and Sergio 2002, Sergio et al. 2006, Smith and Murphy 1979, Steenhof 

et al. 1997). Golden eagles fed primarily on mammals (80 to 90 percent of prey 

items), secondarily on birds, and occasionally on reptiles and fish (Olendorff 1976). 

Preferred mammal prey were leporids (hares [Lepus spp.] and rabbits [Sylvilagus

spp.]), sciurids (ground squirrels [Spermophilus spp.], prairie dogs [Cynomys spp.], 

and marmots [Marmota spp.]) (Kochert et al. 2002). Golden eagles typically foraged in open grassland, sagebrush (Artemisia spp.), and other native shrub communities that provided habitat for these preferred prey species (Collopy and Edwards 

Figure 30—Surrogate species assessment model for golden eagles.
106

GENERAL TECHNICAL REPORT PNW-GTR-907

1989, Smith and Nydegger 1985) and avoided agricultural land and burned areas (Beecham and Kochert 1975, Carrette et al. 2000, López-López et al. 2007, 

Marzluff et al. 1997, Phillips et al. 1984, Sergio et al. 2006). In central California, 

they were reported to forage in open grassland habitats (Hunt et al. 1999). Similar 

patterns were reported elsewhere for winter-habitat-use patterns (Craig et al. 1986, 

Fischer et al. 1984).

Primary foraging areas for golden eagles were located ≤1.9 mi from nesting 

sites (i.e., ≤0.62 mi during the breeding season, ≤1.9 mi during the nonbreeding 

season) (Baglien 1975, Chinnici et al. 2007, Kochert et al. 1999, McGrady et al. 

2002, McLeod et al. 2002). For the spatial scale of this analysis (i.e., watershed), it 

was assumed that all foraging areas within watersheds were equally available to all 

golden eagles nesting in the watersheds.

Fires enhanced by the presence of cheatgrass (Bromus tectorum) have caused 

large-scale losses of foraging habitat in areas used by golden eagles throughout the 

intermountain West (Brooks 1999). Wildfires that burned >98,000 ac of shrublands 

between 1981 and 1987 in the Snake River Birds of Prey National Conservation 

Area adversely affected nesting populations of golden eagles (Kochert et al. 1999). 

Nesting success in burned territories in the Snake River Canyon declined after 

major fires. Abandoned burned territories were generally subsumed by neighboring 

pairs, resulting in a decreased number of nesting pairs. In response to these findings, all potential foraging habitat in the shrub-steppe land cover type that burned 

recently (i.e., since 1987) was removed from consideration as habitat in the model.

Foraging source habitat for golden eagles in this analysis was assumed to be 

low-elevation, native grassland cover type; shrub-steppe cover type that has not 

recently burned; high-elevation, native grassland cover type; and stand initiation 

size/structure within ponderosa pine or Douglas-fir cover types resulting from timber harvest or fire. The size of patches that was considered foraging source habitat 

was ≥5 ac to eliminate small, isolated patches that would not be used for foraging.

To evaluate the relative amount of low-elevation, native grassland; shrubsteppe; and stand initiation habitat within watersheds, we compared the current 

amount of source habitat in the watersheds to the historical median across all 

watersheds with habitat (fig. 30). This historical median was used to develop classes 

to classify degree of departure from the median. To evaluate the relative amount of 

high-elevation, native grassland, we compared the amount in each watershed to the 

median across all watersheds with this habitat. These processes allowed a relative 

comparison of the quantity of source habitat across the watersheds for the entire 

assessment area.
107

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Grazing— 

Management of cattle (Bos taurus) and domestic sheep (Ovis aries) grazing on 

golden eagle foraging habitat can influence prey density, diversity, and availability (Andersen 1991). Prey species generally decreased with reduced herbaceous 

cover and foliage height diversity (Kochert 1989). Bock et al. (1993) suggested that 

raptors would respond negatively to grazing in shrub-steppe habitats, based on the 

ground-cover requirements of their prey. Jackrabbits and ground squirrels may be 

moderately tolerant to grazing, but they disappeared where their habitat was overgrazed (i.e., repeated grazing that exceeds the recovery capacity of the vegetation 

and creates or perpetuates a deteriorated plant community). However, in California, 

Hunt et al. (1995) suggested that ground squirrels were attracted to areas grazed by 

cattle because of the reduced grass height, and that, because ground squirrels were 

a primary prey of golden eagles in the area, golden eagles used grazed grasslands 

for foraging.

The impact of grazing on source habitat within each watershed was characterized by the percentage of source habitat within an active grazing allotment. The 

amount of source habitat in an active grazing allotment was categorized using 10 

percent increments from 0 to 100 percent, with increasing poorer habitat outcomes 

as the proportion of source habitat in an active allotment increased (fig. 30).

Human disturbance— 

Urbanization and human-population growth have made areas historically used by 

golden eagles unsuitable, particularly in southern California (Scott 1985, Thelander 

1974) and the Colorado Front Range (Boeker 1974, Boeker and Ray 1971). 

Extensive agricultural development reduced jackrabbit populations and made areas 

less suitable for nesting and wintering eagles (Beecham and Kochert 1975, Craig 

et al. 1986, Kimsey and Conley 1988, USDI 1979). Increasing tourism was found 

to affect territory occupancy and breeding success of golden eagles in Finland 

(Kaisanlahti-Jokimäki et al. 2008). Human disturbance factors were included in 

models of habitat suitability developed for golden eagles in the European alps 

(Brendel et al. 2002). Evaluation and application of these models led to a recommendation of a 980-ft buffer zone on nest sites for paragliders, climbers, and hikers 

and a 1,640-ft buffer zone on nest sites for helicopters. Holmes et al. (1993) recommended placement of a 980-ft buffer to reduce disturbance of golden eagles on 

winter foraging areas. The effects of human disturbance were addressed through 

building density, roads, and trails as described below.
108

GENERAL TECHNICAL REPORT PNW-GTR-907

Building density— 

Abandoned territories of golden eagles had more dwellings within 1.0 mi and higher 

human populations within 3.0 mi than territories that continued to be occupied 

(Scott 1985). Golden eagles were observed almost exclusively in undeveloped areas 

in central Utah (Fischer et al. 1984). Human impacts may have caused high rates of 

golden eagle nest failure, direct mortality, and territory abandonment in southwestern Idaho (Steenhof et al. 1983) and in Caucasia (Abuladze and Shergalinn 2002). 

Nest sites selected in northern Spain tended to be farther away from villages than 

random sites (Fernandez 1993).

Densities of buildings were calculated within source habitat across the range 

of golden eagles in the assessment area. Singleton and Lehmkuhl’s (2000) characterization of building densities was used to create the following relationships, 

which were used to estimate their effect on habitat quality for golden eagles in this 

analysis (fig. 30):

• Zero: 0 residences/mi2

• Low: >0 to <1.5 residences/mi2

• Moderate: 1.5 to 7.7 residences/mi2

• High: >7.7 residences/mi2

Habitat effectiveness— 

Recreation and other human activity near golden eagle nests can disrupt breeding 

dynamics, but most evidence was equivocal (e.g., Martin et al. 2009). In southwestern Idaho, nest sites were located in areas with fewer roads (Steenhof et al. 1993), 

and proximity of nests to roads may have been related to high rates of nest failure, 

direct mortality, and territory abandonment (Steenhof et al. 1983). Nesting success in Scotland was related inversely to human disturbance around golden eagle 

nests (Watson 1997). Nest sites selected in northern Spain tended to be farther away 

from roads and trails than random sites (Fernandez 1993). Adults spent less time 

at nests and fed young less food less frequently when observers camped 1,300 ft 

versus 2,600 ft from nests in Alaska (Steidl et al. 1993). Mean distance of nest sites 

to roads was 1,500 ft in southeast Wyoming (MacLaren 1986). Flush distance of 

golden eagles increased as distance to roads increased (Holmes et al. 1993). Baglien 

(1975) recommended that roads and other developments be out of sight of nests to 

reduce risk of disturbance.

We estimated the potential for human disturbance to affect nesting habitat 

of golden eagles with an adaptation of the habitat disturbance index described in 

Gaines et al. (2003a). We buffered open roads and trails by 1,640 ft on each side 
109

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

and then intersected this with our map of source habitat. We then used the following categories to characterize the potential effects of human disturbance on golden 

eagles for each watershed (fig. 30):

• Low: >50 percent of the source habitat outside road and trail buffer within a 

watershed.

• Moderate: 25 to 50 percent of the source habitat outside road and trail buffer within a watershed.

• High: <25 percent of the source habitat outside road and trail buffer within 

a watershed.

Variables considered but not included— 

Size of patches of sagebrush has been demonstrated to be related to use of those 

habitats by the golden eagle’s principle prey species (e.g., leporids) (Kochert et 

al. 2002). Mean patch size for jackrabbit use of this habitat was 12,360 ac, with 

increased likelihood of jackrabbit use with increasing patch size and number of 

patches (Knick and Dyer 1997). Also, Carrette et al. (2000) reported a negative 

relationship between increasing number of habitat patches and golden eagle densities. However, this variable was not included in this model because of the difficulty 

in accurately describing size of patches of source habitat with data sets that were 

available to us.

Calculation of historical conditions— 

Values of the model variables were set with the following values to estimate 

historical habitat conditions:

• Nesting habitat

• Forests: 0.5

• Cliffs: Same as current condition

• Foraging

• Low-elevation, native grassland cover type; shrub-steppe: 0.5

• High-elevation, native grassland: Same as current condition

• Stand initiation size/structure within ponderosa pine or Douglas-fir cover 

types: 0.5

• Grazing: None

• Human disturbance

• Building density: Class zero

• Roads and trails: Class low

The relative sensitivity of WI values to variables in the model for golden eagles 

is shown in table 28.
110

GENERAL TECHNICAL REPORT PNW-GTR-907

Model evaluation— 

We used 296 documented occurrence points for golden eagles compared to 296 

random points to evaluate the surrogate species assessment model for this species. 

The mean WI value for the occurrence points (1.251) was significantly higher (t = 

-8.827, P = <0.001) than for the random points (0.905), indicating that our model 

identified habitat conditions favorable to the occurrence of golden eagles.

Assessment Results

Watershed scores— 

Historically, 69 of 72 watersheds within the assessment area provided an adequate 

combination of nesting and foraging habitat for golden eagles. Currently, 86 percent 

(n = 62) of the watersheds contain habitat and were within the present extent of the 

range of golden eagles in the northeast Washington assessment area (Smith et al. 

1997) (fig. 31). Six percent (n = 4) of the 72 watersheds did not contain any cliffnesting source habitat, 47 percent (n = 34) of the watersheds provided low to moderate amounts, and 47 percent (n = 34) of the watersheds provided a high amount. 

Watersheds with a high amount of cliff nesting habitat were generally located in the 

northeast, northwest, and central portions of the assessment area. Thirty-six percent 

(n = 26) of the watersheds were at or above the median amount of forested nesting habitat calculated across all watersheds; 65 percent (n = 46) of the watersheds 

were below the median amount (fig. 31). Watersheds with high amounts of forested 

nesting habitat were primarily located in the northwest and central portions of the 

assessment area.

Currently, 53 percent (n = 33) of the watersheds with habitat had moderate WI 

scores (>1.0 to <2.0) (fig. 31). These watersheds were concentrated in the southwestern portion of the assessment area. Forty-seven percent (n = 29) of the watersheds 

Table 28—Relative sensitivity of 

watershed index values to variables

in the model for golden eagles

Variable Sensitivity rank

Cliff nesting habitat 1

Shrub and grass departure 2

High-elevation grassland 3

Grazing impact 3

Roads and trails 4

Building density 4

Forest nesting habitat 5

Stand initiation departure 6
111

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

had low WI scores (>0.0 to ≤1.0). These were generally distributed across the 

northern and central portions of the assessment area.

Watersheds with the least loss of low-elevation grassland and shrub-steppe 

foraging habitat were located in the central portion of the assessment area (fig. 31). 

Foraging habitat associated with forest stand initiation was limited but occurred 

throughout the western portion of the assessment area. Grassland foraging habitat 

Figure 31—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for golden eagles (GOEA) by watershed in the northeast Washington assessment area (NEWA).
112

GENERAL TECHNICAL REPORT PNW-GTR-907

at high elevation was located across the western and northeastern portions of the 

assessment area.

Factors that influenced the WI scores included the amount of nesting source 

habitat (i.e., cliff and forest) compared to the median amount across watersheds and 

foraging source habitat (i.e., low-elevation grassland and shrub-steppe, forest initiation following timber harvest and fire, high-elevation grassland) compared to levels 

historically available in the watersheds. The effect of grazing on foraging habitat 

was assessed by the amount of habitat in an active grazing allotment. Watersheds 

with >25 percent of source habitats for golden eagles in an active grazing allotment 

(34 percent, n = 21) were concentrated in the central portion of the assessment area.

Twenty-seven percent (n = 17) of the watersheds in the assessment area had low 

influence from open roads on golden eagle source habitat (i.e., >50 percent of the 

source habitat was outside a 1,640-ft buffer on roads and trails). These watersheds 

were primarily located in the northwest portion of the assessment area. Across the 

assessment area, a large majority of the watersheds (79 percent, n = 49) had a low 

density of buildings in >50 percent of the source habitat. Watersheds with higher 

building densities primarily occurred in the central part of the assessment area 

(fig. 31).

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier) and a habitat distribution index. The WWI scores indicated that the current habitat capability for 

golden eagles within the assessment area was 67 percent of the historical capability. 

Dispersal across the assessment area was not considered an issue for this species. 

All ecoregions contained at least one watershed with >40 percent of the median 

amount of historical source habitat (median was calculated across all watersheds 

with source habitat). Seventy-four percent (n = 53) of watersheds had >40 percent 

of the median amount of historical source habitat. Under those circumstances, there 

was a 32.0 percent probability that the current viability outcome for golden eagles is 

A and 56 percent probability of outcome B, indicating habitats are broadly distributed and of high abundance, but there are gaps where suitable environments are absent or only present in low abundance (fig. 32). Likely, other species associated with 

the woodland/grass/shrub group in the woodland/grass/shrub family have similar 

outcomes.

Historically, dispersal across the assessment area was not considered an issue 

for this species. All ecoregions contained at least one watershed with >40 percent 

of the median amount of historical source habitat (median was calculated across 
113

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Figure 32—Current and historical viability outcomes for golden eagles in the northeast Washington 

assessment area.

all watersheds with source habitat). Eighty-six percent (n = 62) of watersheds had 

>40 percent of the median amount of historical source habitat. Under those circumstances, there was an 80.8 percent probability that the historical viability outcome 

for golden eagle was A, indicating habitats were broadly distributed and highly 

abundant (fig. 32).

In summary, under historical conditions, golden eagles and other species 

associated with the woodland/grass/shrub group in the woodland/grass/shrub family were likely well distributed throughout the assessment area. Currently, although 

they are likely well distributed throughout most of the assessment area, their 

distribution has been somewhat reduced from historical conditions.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Reduction and fragmentation of foraging source habitat.

2. Effects of grazing on foraging source habitat.

3. Negative effects of roads and building use in nesting source habitats.

4. The sustainability of dry forests as nesting source habitat for golden eagles 

(Townsley et al. 2004).
114

GENERAL TECHNICAL REPORT PNW-GTR-907

Harlequin Duck 

Introduction

Harlequin ducks were selected as a surrogate species to represent the forested riparian group, specifically at mid-low elevations. Harlequin ducks breed and use summer habitats in mountain streams on the east and west side of the Cascade Range, 

in the Selkirk Mountains in northeastern Washington, and in the Blue Mountains 

(Jewett et al. 1953, Schirato 1994). Their presence in the Blue Mountains is now in 

question (Schirato 1994); however, in northeastern Washington, they are still a good 

surrogate species for this group because of their association with smaller midelevation streams and because human disturbance is a risk factor. Other species in 

this group, including several duck species, have similar habitat associations and risk 

factors. 

Model Description

Source habitat— 

Breeding habitat for Harlequin ducks occurs on streams as reaches with average gradients between 1 and 7 percent, with some areas of shallow water (riffles), 

clear water, rocky, gravel to boulder-size substrate, and forested bank vegetation 

(Bengtson and Ulfstrand 1971, Lewis and Kraege 1999).

Streams usually have substrate that ranges from cobble to boulder, with 

adjacent vegetated banks. Harlequins often nest on the ground (Bengtson 1972); 

however, cavities in trees and cliff faces also provide nest sites (Cassier and Groves 

1989, Cassier et al. 1993). Midstream loafing sites are an important part of suitable 

habitat (Cassier and Groves 1989, Cassier et al. 1993). Broods remain near nesting 

areas for the first few weeks after hatching, then move downstream during the summer (Cassier and Groves 1989, Cassier et al. 1993, Kuchel 1977, Wallen and Groves 

1989). Broods prefer low-gradient streams with adequate macro invertebrate food 

sources (Bengtson and Ulfstrand 1971). Aquatic insect larvae make up the bulk of 

their diet during the breeding season (Cassier and Groves 1989, Cassier et al. 1993).

We modeled source habitat for harlequin ducks using a stream-order layer and a 

330-ft distance buffer from stream orders 6 and 7 (fig. 33). 

Late-successional habitat— 

Cassier and Groves (1989) found that harlequins preferred to nest in areas where 

mature and old-growth forests occurred adjacent to suitable streams. Therefore, we 

used the amount of late-successional forest within source habitat as a variable to describe habitat quality. We mapped late-successional forest using the following GIS 

data layers (fig. 33):
115

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

• Tree structure and size: Single/multilayer, >15 in QMD

• Canopy closure: >50 percent

We then intersected the source habitat and late-successional forest layers and 

used the following categories to assess the influence of late-successional forest on 

harlequin duck source habitat within each watershed (fig. 33):

• Zero: No source habitat composed of late-successional forest

• Low: >0 to 20 percent of the source habitat composed of late-successional 

forest

• Moderate: >20 to 50 percent of the source habitat composed of latesuccessional forest

• High: >50 percent of the source habitat composed of late-successional 

forest

Habitat effectiveness— 

Studies have shown that harlequin ducks are sensitive to human disturbances during the breeding season (Cassier and Groves 1989, Wallen and Groves 1989). Ashley 

(1994) found that harlequin ducks use stream habitats inaccessible to humans more 

than expected. Wallen and Groves (1989) reported that fishing along trails seemed 

more disruptive to harlequin ducks than hiking. Harlequins avoided humans on 

Figure 33—Surrogate species assessment model for harlequin ducks.
116

GENERAL TECHNICAL REPORT PNW-GTR-907

the bank or in the streambed and would typically swim or dive downstream past 

people, remaining partially submerged and watchful while moving out of the area. 

Fishing also can directly affect harlequin ducks as birds have been found entangled 

in fishing line (Ashley 1994, Clarkson 1992). Cassier and Groves (1989) recommended that trails and roads be located at least 160 ft from streams used by harlequin ducks.

To evaluate the potential effects of human activities on harlequin duck source 

habitat, we used the harlequin duck nesting habitat disturbance index in Gaines et 

al. (2003a) in which roads and trails are buffered by 160 ft on each side. We then 

intersected this data layer with our source habitat map and developed the following 

categories to assess habitat effectiveness within each watershed (fig. 33):

• Low habitat effectiveness: >50 percent of the source habitat in a zone of 

influence of a road or trail

• Moderate habitat effectiveness: 30 to 50 percent of the source habitat in a 

zone of influence of a road or trail

• High habitat effectiveness: <30 percent of the source habitat in a zone of 

influence of a road or trail

Calculation of historical conditions—

• Departure of source habitat: Departure class 1

• Late-successional forest: Moderate

• Habitat effectiveness: High

The relative sensitivity of watershed values to variables used in the model for 

harlequin ducks is shown in table 29.

Table 29—Relative sensitivity of 

watershed index values to variables in 

the model for harlequin ducks

Model variables

Order of variable 

weighting

Source habitat 1

Late-successional forest 2

Habitat effectiveness 3
117

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Assessment Results

Watershed scores— 

Twenty-seven (45 percent) of the watersheds had high WI scores (>2.0), and 31 

(52 percent) had moderate scores (1.0 to 2.0). The WI variables for those watersheds 

with a WI of <2.0 indicate that the quality of habitat is likely affected by a low 

amount of late-successional habitat, or habitat effectiveness may be low.

Watersheds with the most source habitat (>2,500 ac) included North Lake Roosevelt, Lower Tieton, Boulder/Deadman, Wenas Creek, Naches River, Upper Pend 

Orielle, Stensgar/Stranger, Upper Yakima, Upper Columbia-Swamp Creek, Middle 

Methow, Cowiche, and the Wenatchee Rivers. The median amount of habitat across 

all watersheds with at least some source habitat (59 watersheds) was 1,600 ac. Six 

watersheds had <250 ac of source habitat (Bumping River, Ruby Creek, Upper 

Tieton River, Mad River, Columbia Tribs). Watersheds that have a high proportion 

of source habitat on federal lands include Boulder/Deadman, Chiwawa, Cle Elum, 

Icicle, Little Naches, Lower Chewuch Lower Pend Oreille, Lower Tieton, Naches, 

Nason, West Fork San Poil, and White-Little Wenatchee. 

The proportion of the source habitat that was in late-successional forest, an 

indicator of habitat quality, was low overall. Fifty-three percent of the watersheds 

(n = 31) had no late-successional habitat within the source habitat, 44 percent (n = 

26) had a low level (>0 to 20 percent) of late-successional forest in source habitat, 

3 percent (n = 2) had a moderate (>20 to 50 percent) level of late-successional forest 

in source habitat, and no watersheds had a high level (>50 percent).

Fifty-nine percent of the watersheds (n = 35) had a low level of human disturbance (<30 percent of the source habitat in a disturbance buffer), 37 percent (n = 22) 

had a moderate level of human disturbance (30 to 50 percent of the source habitat in 

a disturbance buffer), and 3 percent (n = 2) had a high level of human disturbance 

(>50 percent of the source habitat in the disturbance buffer).

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier) and a habitat 

distribution index. The WWI scores indicated that the current habitat capability 

for harlequin ducks across the assessment area was 68 percent of the historical 

capability. This score was largely influenced by the amount of late-successional forest that is in the source habitat and the level of human disturbance that is currently 
118

GENERAL TECHNICAL REPORT PNW-GTR-907

occurring within the source habitat. Many of the roads, trails, and recreation facilities occur within the valley bottoms and adjacent to harlequin duck habitat.

Forty percent of the historical median amount of source habitat across all watersheds with at least some source habitat was 657 ac. Historically and currently, 49 of 

the watersheds (83 percent) in the assessment area met this habitat minimum. The 

watersheds with >40 percent were distributed across all of the five ecoregions.

The VOI for the assessment area had a 34 percent probability of outcome A and 

a 57 percent probability of outcome B (fig. 34), which indicates that suitable environments for the harlequin duck are broadly distributed and of relatively high abundance, but there are gaps where suitable environments are absent or only present in 

low abundance. These gaps are typically not large enough to prevent species from 

interacting as a metapopulation. Historically, there was an 80.8 percent probability 

of outcome A and a 13.3 percent probability of outcome B where suitable environments were more broadly distributed or of high abundance (fig. 34). In addition, 

the suitable environments were better connected, allowing for interspecific interactions. A reduction in the availability of suitable environments for harlequin ducks 

may have occurred in the assessment area compared to the historical distribution 

and condition of their habitats, but their source habitats are still relatively widely 

Figure 34—Current and historical viability outcomes for the harlequin duck in the northeast Washington 

assessment area.

 A reduction in the 

availability of suitable 

environments for 

harlequin ducks 

may have occurred 

in the assessment 

area compared to the 

historical distribution 

and condition of their 

habitats, but their 

source habitats are 

still relatively widely 

distributed.
119

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

distributed across the assessment area. Similar outcomes are expected for other 

species associated with forested riparian habitats.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. The amount of late-successional forest adjacent to streams that provide 

source habitat for harlequin ducks is low in many watersheds.

2. The level of human activities that occurred within harlequin duck source 

habitat reduced the effectiveness of their habitat, especially because many 

of the roads, trails, and recreation facilities occur within the valley bottoms 

and thus are adjacent to harlequin duck habitat.

Larch Mountain Salamander

Introduction

The larch mountain salamander is a surrogate species for the cool-moist forest with 

medium to large trees group. In addition, this species is closely associated with 

talus, a fine-scale habitat feature. The distribution of the larch mountain salamander 

in Washington is disjunct, with most known sites located in southern Washington, 

north of the Columbia River Gorge. However, two isolated populations have been 

found near Snoqualmie Pass (Crisafulli 1999, Nordstrom and Milner 1997). Within 

the assessment area, they are currently known to occur only in the Upper Yakima 

River watershed.

Because of the limited distribution of this species within the assessment area, 

and its unique habitat that we did not have spatial data to evaluate, a surrogate 

species assessment model was not developed for this species; rather a qualitative 

assessment of its habitat relationships and general management considerations were 

completed.

Source habitat— 

Larch mountain salamanders depend on the availability of undisturbed, shaded talus slopes with stable, moist microclimates (Herrington and Larsen 1985, 

Nordstrom and Milner 1997). In addition, they have been discovered in moist forests that possess late-seral features such as complex stand structure and moderate to 

high levels of woody debris (Crisafulli 1999). 

Risk factors— 

The risk factors that were identified for the larch mountain salamander include 

the effects of road construction, timber harvest, and high-intensity fire on key 
120

GENERAL TECHNICAL REPORT PNW-GTR-907

habitat elements (talus, woody debris) and on changes to microclimate conditions 

(Crisafulli 1999, Herrington and Larsen 1985, Nordstrom and Milner 1997).

Management Considerations

The following issues were identified for consideration by managers:

1. Predisturbance surveys may be implemented where suitable habitat conditions occur following standardized protocols (Crisafulli 1999).

2. Microclimates and habitat features such as woody debris and talus can be 

influenced by management activities.

Lark Sparrow 

Introduction

Lark sparrows were chosen as a surrogate species to represent species of conservation concern in the grassland group of the woodland/grass/shrub family. Lark sparrows and other species in the grassland group are of conservation concern because 

grassland habitats throughout the United States are being lost to woody plant 

invasion and development (Grant et al. 2004). Lark sparrows were associated with 

dry, open grasslands and respond positively to well-managed grazing of domestic 

livestock, although they are highly susceptible to nest parasitism by brown-headed 

cowbirds (Molothrus ater). They have a distinctive song, making this species easy 

to survey and monitor. Lark sparrows range across the central portion of the assessment area and in part of the eastern portion (Smith et al. 1997). Lark sparrows are 

breeding-season residents of the assessment area (Martin and Parrish 2000); this 

assessment is for nesting and rearing habitat.

Model Description

Source habitat— 

Lark sparrow habitat included shrub-steppe, and mixed-grass and shortgrass uplands with a shrub component and sparse litter (Bock et al. 1995, Walcheck 1970, 

Wiens and Rotenberry 1981). Martin and Parrish (2000) reported that lark sparrows prefer structurally open herbaceous ground cover containing scattered trees 

or shrubs with <24 percent canopy cover. In northeastern Colorado, lark sparrows 

were found in grazed prairies with widely spaced cottonwoods (Fitzgerald 1978, 

Jacobson 1972). In piñon-juniper woodlands, lark sparrow abundance increased 

with decreasing tree density (Tazik 1991). Studies in the Eastern United States indicated that habitat patches with >15 percent tree cover were avoided by nesting lark 

sparrows (Coulter 2008). Also, lark sparrows were significantly more abundant in 
121

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

native-grass-dominated areas than in areas dominated by exotic grasses (Flanders 

et al. 2006). Lark sparrow abundance has been reported to be negatively correlated 

with sagebrush density (McAdoo et al. 1989). Lark sparrow habitat in Arizona had 

mean values of 38 percent bare ground, 54 percent grass cover, 7 percent forb cover, 

<2 percent canopy cover, 5-in grass height, and 0.73 shrubs/ft2 (Bock and Webb 

1984). For this analysis, source habitat was defined as structurally open habitats 

with grass or herbaceous ground cover with scattered shrubs or trees (fig. 35). 

Figure 35—Surrogate species assessment model for lark sparrows.
122

GENERAL TECHNICAL REPORT PNW-GTR-907

Invasive animals— 

Lark sparrows were vulnerable to parasitism by brown-headed cowbirds (Hill 1976, 

Newman 1970, Shaffer et al. 2003). Proximity to agricultural areas increased the 

potential of parasitism (Goguen and Mathews 1999, 2000; Tewksbury et al. 1999; 

Young and Hutto 1999). The following classes were used to estimate the potential 

effect of brown-headed cowbirds on lark sparrows (fig. 35):

• Low: <30 percent of source habitat within 1.2 mi of agricultural areas within a 

watershed

• Moderate: 30 to 50 percent of source habitat within 1.2 mi of agricultural 

areas within a watershed

• High: >50 percent of source habitat within 1.2 mi of agricultural areas within a 

watershed

Patch size— 

In the core of their range, lark sparrows often inhabit large, unbroken prairies or 

fields (Martin and Parrish 2000). At the landscape scale, lark sparrows used large 

habitat patches with low edge to interior ratios (Coulter 2008). Proximity of habitat 

patches and amount of edge were reported to be important predictors of grassland 

bird richness (including lark sparrows) (Hamer et al. 2006). Lark sparrows were 

more frequently found in interior survey plots >650 ft from an edge in a habitat 

patch than in survey plots closer to an edge (Bock et al. 1999). They were edge 

sensitive with reduced abundance near edges (Bolger et al. 1997). This suggests that 

patches increasingly >32 ac provide progressively better habitat. They also exhibited a negative response to urban development (Jones and Bock 2002). Lark sparrows 

were strongly negatively affected by habitat fragmentation and preferred patches 

>250 ac (Bolger 2002). Occurrence of grassland species may be negatively affected 

by larger amounts of edge because of increased risk of predation and brood parasitism near wooded edges (Johnson and Temple 1990, Winter et al. 2000). The following classes were used to estimate the potential effect of patch size on lark sparrows 

(fig. 35):

• Small: <50 ac mean size for source habitat patches within a watershed

• Medium: 50 to 250 ac mean size for source habitat patches within a 

watershed

• Large: >250 ac mean size for source habitat patches within a watershed
123

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Grazing— 

Results reported in the literature on the effects of grazing on lark sparrows were 

unequivocal. Numerous sources reported a positive response from lark sparrows 

associated with livestock grazing (Bock and Webb 1984, Bock and Bock 1988, 

Bock et al. 1984, Lusk et al. 2003, Martin and Parrish 2000). However, timing and 

intensity of grazing may affect the magnitude of the response of lark sparrows 

(Goguen and Mathews 1998).

Impact of grazing on source habitat within a watershed was based on the 

percentage of source habitat with an active grazing allotment. The amount of source 

habitat in an active grazing allotment was categorized using 10 percent increments 

from 0 to 100 percent, with increasing habitat outcomes as the proportion of source 

habitat in an active allotment increased (fig. 35).

Calculation of historical conditions—

Values of the model variables were set with the following values to estimate historical habitat conditions:

• Departure of source habitat from HRV: 0.5

• Invasive animals: Class low

• Patch size: Class large

• Grazing: None

The relative sensitivity of WI values to variables used in the model for lark 

sparrow are shown in table 30.

Assessment Results

Watershed scores— 

Historically, 71 of 72 watersheds within the assessment area provided habitat for 

lark sparrows (i.e., >50 ac of habitat within the watershed). However, most of those 

watersheds either no longer support habitat for lark sparrows or historical amounts 

Table 30—Relative sensitivity of watershed index values to variables in the 

model for lark sparrow

Variable Sensitivity rank

Habitat departure 1

Patch size 2

Grazing impact 3

Invasive species 4
124

GENERAL TECHNICAL REPORT PNW-GTR-907

have been significantly reduced (fig. 36). Forty-five percent (n = 32) of watersheds 

that had habitat historically for lark sparrows no longer have habitat. However, those 

watersheds historically had minimal amounts that were likely highly fragmented. 

Watersheds with habitat remaining were concentrated in the central and south-central portions of the planning area. Seven percent (n = 5) of those watersheds supported >2,470 ac of source habitat (fig. 36) and had WI scores that were moderate 

Figure 36—Current amount of (A) source habitat (acres), (B) current habitat depature, (C) watershed index, and (D) 

habitat condition class for lark sparrow (LASP) by watershed in the northeast Washington assessment area (NEWA).
125

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

or higher (>1.0) (fig. 36). The remaining 27 percent (n = 19) of watersheds that were 

within the current range of lark sparrows had low WI scores (>0.0 and <1.0).

A major factor that influenced the WI scores was the amount of source habitat 

compared to levels historically available in the watersheds. Watersheds that currently had the greatest amount of source habitat included Columbia River–Lynch 

Coulee, Columbia Tributaries, Lake Entiat, Lower Okanogan River; and Okanogan 

River–Bonaparte Creek, and Okanogan River–Omak Creek (fig. 36). However, 

none of those watersheds had >25 percent of the source habitat managed by federal 

agencies. The watersheds with the least amount of source habitat were located 

across the eastern and western portions of the assessment area.

Lark sparrows were strongly negatively affected by habitat fragmentation and 

preferred patches >250 ac (Bolger 2002). However, essentially all remaining source 

habitat for lark sparrows has been highly fragmented. Lark sparrows are also vulnerable to brood parasitism by brown-headed cowbirds (Newman 1970). Proximity 

to agricultural areas increases the potential of parasitism (Goguen and Mathews 

2000). Basically, all remaining source habitat for lark sparrows was at high risk to 

brood parasitism. Grazing by livestock may have a positive effect on lark sparrows 

and their habitat depending on the intensity and season of grazing (Bock and Webb 

1984). The percentage of source habitat by watershed that was grazed was generally 

low to moderate across the assessment area (fig. 36).

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability for 

lark sparrows within the assessment area was 44 percent of the historical capability. 

Dispersal across the assessment area was not considered an issue for this species. 

Four of five ecoregions contained at least one watershed with >40 percent of the 

median amount of historical source habitat (median was calculated across all watersheds with source habitat). Eighteen percent (n = 13) of watersheds had >40 percent 

of the median amount of historical source habitat. Under those circumstances, there 

is a 45 percent probability that the current viability outcome for lark sparrows is C, 

and a 52 percent probability that the current viability outcome for lark sparrows is 

D, indicating that habitat was patchily distributed or isolated and in low abundance 

(fig. 37). It is likely that other species associated with the grassland group of the 

woodland/grass/shrub family had similar outcomes.

Historically, dispersal across the assessment area was not considered an issue 

for this species. Four of five ecoregions contained at least one watershed with >40 

percent of the median amount of historical source habitat (median was calculated 
126

GENERAL TECHNICAL REPORT PNW-GTR-907

across all watersheds with source habitat). Sixty-two percent (n = 45) of watersheds 

had >40 percent of the median amount of historical source habitat. Under those 

circumstances, there was a 71.2 percent probability that the historical viability 

outcome for lark sparrows was A, and a 18.8 percent probability that the historical 

viability outcome for these species was B, indicating habitat was broadly distributed with a high abundance of quality habitat (fig. 37).

In summary, under historical conditions, lark sparrows and other species 

associated with the grassland group of the woodland/grass/shrub family were likely 

numerous and well distributed throughout the assessment area. However, under 

current conditions, populations of these species are likely not well distributed 

across the assessment area with substantial potential for extirpation of individual 

populations.

Our results for this species were similar to those reported in the broad-scale 

habitat analysis by Wisdom et al. (2000) in ICBEMP. According to the ICBEMP, 

terrestrial vertebrate habitat analyses, historical source habitats for lark sparrows 

included portions of the Northern Cascades and the Northern Glaciated Mountains 

ERUs that overlap our assessment area (Wisdom et al. 2000). Within this historical 

habitat, declines in source habitats have been extensive, -61 percent in the Northern Cascades and -84 percent in the Northern Glaciated Mountains according to 

Wisdom et al. (2000).

Figure 37—Current and historical viability outcomes for lark sparrows in the northeast Washington 

assessment area.
127

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Reduction and fragmentation of suitable grassland source habitats.

2. Negative effects of agricultural practices adjacent to source habitats that 

promote nest parasitism by brown-headed cowbirds.

Lewis’s Woodpecker 

Introduction

Lewis’s woodpecker was chosen as a surrogate species for the postfire group to 

represent postfire habitat with lower densities of large snags and trees present 

as compared to other species in the group that prefer postfire habitat with a high 

density of fire-killed trees. This species was selected as a surrogate species because 

it is closely tied to postfire habitats, is widespread across the Western United States, 

and occurs in suitable habitat across the assessment area. This woodpecker is also 

associated with unburned ponderosa pine forests with open canopies and large trees 

as well as cottonwood/willow habitat. However, it generally is at lower abundance 

in these habitats than in postfire habitat.

Model Description

Source habitat— 

Lewis’s woodpeckers breed in wooded areas with an open canopy, often with a 

dense shrub cover, and generally avoid dense forest. Three main habitats used 

throughout its range are burned or logged areas, open ponderosa pine savanna at 

high elevations, and riparian woodland dominated by large cottonwoods at low 

elevations (Abele et al. 2004, Bock 1970, Saab and Dudley 1998, Saab and Vierling 

2001, Tobalske 1997). Suitability of burned areas as habitat for Lewis’s woodpeckers may vary with size of burn, time since burn, intensity of burn, and geographic region (Russell et al. 2007, Saab and Dudley 1998, Saab and Vierling 2001, 

Tobalske 1997). Research by Russell et al. (2007) found that the best predictors of 

nest location for Lewis’s woodpeckers after a wildfire in Idaho were burn severity, 

patch area, and snag diameter. In a Wyoming study, nests were preferentially located within or adjacent to burned ponderosa pine forests, and in sites with greater 

ground cover, more down logs, and greater amounts of open sky than random sites 

(Linder and Anderson 1998). Linder and Anderson (1998) found that use was declining in an area that burned 20 years earlier.
128

GENERAL TECHNICAL REPORT PNW-GTR-907

Optimal canopy closure for nest sites was <30 percent (Linder and Anderson 

1998, Sousa and Farmer 1983). Some studies have suggested that Lewis’s woodpeckers require a shrubby understory (Bock 1970, Sousa and Farmer 1983), while 

others have shown that preferred habitat included a relatively sparse shrub layer 

(<18 percent) (Block and Brennan 1987, Linder and Anderson 1998). In winter, this 

species occupies a variety of habitat types that offer proximity to mast, fruit, or 

corn. Typically, these are oak woodlands or orchards. In portions of the Southwest, 

this species may winter in areas without mast (Bock 1970).

Saab and Vierling (2001) found that some cottonwood riparian forests, primarily near agricultural development, may be acting as sink habitat. More research on 

the productivity of Lewis’s woodpeckers in different habitat types is needed.

We identified both primary and secondary source habitat for the Lewis’s 

woodpecker (fig. 38). Primary source habitat for this analysis was characterized as 

forested habitat in the dry potential vegetation types that was burned in the past 5 

years (year >1999–2003) and was salvage harvested. We also included areas that 

were burned in the previous 5 to 15 years (1985–1999) regardless of salvage history but without any regeneration harvest. Secondary habitat was characterized 

as any forested areas in the dry potential vegetation type and Oregon white oak 

with a canopy closure <50 percent and tree d.b.h. >15 in QMD. We also included 

cottonwood/willow habitat that was primarily located in riparian areas as secondary source habitat. Cottonwood/willow habitats were mapped using the National 

Wetlands Inventory data. 

We identified primary source habitat as:

• Potential vegetation types: Dry forests

• Postfire habitat 1999–2003, salvage harvested in all forested cover-types

• Postfire habitat 1985–1999 in all forested cover types

We identified secondary source habitat as:

• Potential vegetation types: Dry forests

• Cover types: Ponderosa pine, riparian and deciduous 

• Tree size: >15 in QMD 

• Canopy closure: >50 percent 

• National Wetlands Inventory: Palustrine forested wetlands

Snag habitat— 

Unlike other woodpeckers, Lewis’s woodpecker is not morphologically well adapted to excavate cavities in hardwood (Spring 1965). Lewis’s woodpeckers tend to 

nest in a natural cavity, reuse preexisting cavities, or excavate a new cavity in a soft 
129

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

snag (Harrison 1979, Raphael and White 1984, Saab and Dudley 1998, Tobalske 

1997). Mated pairs may return to the same nest site in successive years. On partially 

logged burns with high nesting densities in Idaho, nest sites were characterized 

by the presence of large, soft snags and an average of 150 snags/acre, >9 in d.b.h. 

(Saab and Dudley 1998). Galen (1989) in eastern Oregon found that in unburned 

ponderosa pine/Oregon white oak habitat the mean d.b.h. of nest trees was 26 in 

with a range of 12.5 to 43 in. Haggard and Gaines (2001) in northeast Washington 

found Lewis’s woodpeckers in postfire habitat were more abundant in areas with 

<12 snags/acre >10 in d.b.h. and were not found in areas with >91 snags/acre >10 in 

d.b.h.) following salvage logging of the burn. Saab et al. (2009) also found Lewis’s 

woodpecker nest sites were primarily associated with partially logged burns.

In primary habitat (postfire), we assumed snag density was adequate for this 

species. In secondary habitat, we calculated the percentage of source habitat within 

each watershed that had densities of snags >20 in d.b.h. in the following classes 

based on data from Harrod et al. (1998): low <5/ac, moderate 7/ac, high 10/ac, and 

very high >12/ac (fig. 38).

Figure 38—Surrogate species assessment model for Lewis’s woodpecker.
130

GENERAL TECHNICAL REPORT PNW-GTR-907

Road density— 

Bate et al. (2007) found that snag numbers were lower adjacent to roads owing to 

safety considerations, firewood cutters, and other management activities. Other 

literature has also indicated the potential for reduced snag abundance along roads 

(Gaines et al. 2003a, Wisdom and Bate 2008, Wisdom et al. 2000). To account for 

reduced snag density along roads, we calculated the percentage of forests in the 

dry potential vegetation types in the following road density classes by watershed 

(fig. 38):

• Zero: <0.1 mi/mi2

 open roads in watershed

• Low: 0.1 to 1.0 mi/mi2 open roads in watershed 

• Moderate: 1.1 to 2.0 mi/mi2 open roads in watershed

• High: >2.0 mi/mi2 open roads in watershed

Historical inputs for surrogate species assessment model—

• Departure of primary source habitat: Class 1

• Departure of secondary source habitat: Class 1

• Secondary habitat snag density: High

• Road density: Zero

The relative sensitivity of WI values to variables used in the model for Lewis’s 

woodpecker are shown in table 31.

Assessment Results

Watershed scores— 

Primary habitat was below the historical median in most watersheds (n = 65, 92 

percent) (fig. 39). The remaining six watersheds contained most of the existing primary source habitat with all having >3,700 ac of source habitat (fig. 39). All of these 

watersheds have experienced recent wildfires. The amount of primary source habitat in the Entiat drainage (43,000 ac) makes up nearly 40 percent of the total amount 

of primary source habitat in the assessment area. Overall, nine watersheds currently 

have >2,300 ac of primary source habitat, the amount calculated as 40 percent of 

the historical median amount of source habitat. These watersheds are Curlew, Icicle 

Creek, Okanogan River-Bonaparte, Peshastin Creek, Wenatchee River, Mad River, 

Lower Lake Chelan, Lake Entiat, and Entiat River. 

In addition to the large reduction in primary source habitat, the amount of 

secondary source habitat is also far below the historical median (fig. 39). The three 

watersheds that are near or above the historical median for amount of secondary 

habitat are the Okanogan River-Omak Creek, Upper Okanogan River, and Okanogan River-Bonaparte Creek. 
131

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 31—Relative sensitivity of watershed 

index values to variables in the model for 

Lewis’s woodpecker

Variable Sensitivity rank

Primary habitat departure 1

Secondary habitat departure 2

Snag density 3

Road density 4

Figure 39—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watrshed index, and (D) 

habitat condition class for Lewis’s woodpecker by watershed in the northeast Washington assessment area.
132

GENERAL TECHNICAL REPORT PNW-GTR-907

Of the 71 watersheds assessed in the assessment area, 90 percent (n = 64) had 

a WI of low current (<1.0 ) (fig. 39). Two watersheds were moderate (>1.0 and <2.0) 

and five watersheds had a high score (> = 2.0). The five watersheds in the high class 

have all experienced recent wildfire activity and include Entiat River, Peshastin 

Creek, Icicle Creek, Mad River, and Lake Entiat.

Although snag densities in secondary habitat were primarily in the low class 

(<5/ac), the low WI scores were primarily indicative of the overall low amount of 

both primary and secondary source habitats.

Our results for declining habitats for this species are similar to other broadscale habitat analysis by Wisdom et al. (2000) in the ICBEMP. According to 

the ICBEMP terrestrial vertebrate habitat analyses, historical source habitats 

for Lewis’s woodpeckers included only portions of the Northern Cascades and 

the Northern Glaciated Mountains ERUs (Wisdom et al. 2000). The analysis by 

Wisdom et al. (2000) would be the most equivalent of our analysis of the trend in 

secondary habitat. Within this historical habitat, declines in source habitats have 

been extensive—80 percent in the Northern Cascades and 95 percent in the Northern Glaciated Mountains (Wisdom et al. 2000). Within the entire interior Columbia 

Basin, there have been widespread declines in source habitats (83 percent)—the 

greatest of any species analyzed (Wisdom et al. 2000).

Viability outcome— 

Currently, the viability outcome is a 60 percent C and a 40 percent D, indicating 

habitats are patchily distributed or isolated and are in low abundance. Historically, 

the outcome was primarily an A (76 percent), indicating habitats were broadly distributed and in high abundance (fig. 40)

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability 

for Lewis’s woodpecker within the assessment area is 67 percent of the historical 

capability. This index is a bit misleading because current primary habitat in two 

watersheds is about five times as great as their historical median (Lake Entiat and 

Entiat River) and is largely the cause for this relatively high value currently. Onehalf of the current total WWI is a result of the sum of these two watersheds that 

have experienced recent wildfire activity.

The main factor leading to a lower current viability outcome compared to the 

estimated historical outcome was the reduction in percentage of watersheds with 

recent postfire habitat. Historically, 76 percent (n = 54) of the watersheds contained 

40 percent of the median historical amount of postfire habitat, while currently, 

primary habitat is not well distributed across the assessment area, occurring in 
133

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

this quantity in only 13 percent (n = 9). Three of five ecoregions contained at least 

one watershed with >40 percent of the median amount of historical source habitat 

(median was calculated across all watersheds with source habitat).

Under historical conditions, the Lewis’s woodpecker and other species associated with the postfire group were likely well distributed across the assessment 

area. Currently, we estimated that both the abundance and distribution of suitable 

environments for these species has declined and led to a decline in viability from a 

projected A outcome to a D outcome.

Management Considerations

The following issues were identified during this assessment and from the published 

literature regarding the Lewis’s woodpecker, and other species associated with the 

postfire group for consideration by managers:

1. Timber harvest, firewood collection, and postfire salvage harvest may 

affect the availability of large snags used for nesting and foraging (Wisdom 

et al. 2000). There has been a decline in the amount of both primary (postfire) and secondary (large, open forest and cottonwood/willow) source habitat throughout the dry forests across the assessment area.

2. Wildfire intensity, postfire salvage logging and firewood collection influence the distribution of snags suitable for nesting and perching sites (Abele 

et al. 2005, Saab et al. 2009). 

Figure 40—Current and historical viability outcomes for the Lewis’s woodpecker in the northeast Washington 

assessment area.
134

GENERAL TECHNICAL REPORT PNW-GTR-907

3. Alterations to water regimes have been shown to negatively affect cottonwood recruitment along many western streams and rivers (Johnson and 

Haight 1984). 

4. Fire-suppression efforts in eastern Washington dry forests have resulted in 

stands with increased stem densities (often of more shade-tolerant species 

such as Douglas-fir and grand fir), reduced shrub and grass understories, 

and increased canopy closure (Morgan 1994). The resulting forest structure 

is apparently not suitable as a breeding habitat owing to reductions in insect 

populations and limited space for foraging activity (Abele et al. 2005).

MacGillivray’s Warbler

Introduction

MacGillivray’s warbler was selected as a surrogate species to represent shrubbydeciduous habitats within the deciduous riparian group. This warbler’s distribution 

is large and widespread across the assessment area during the breeding season. The 

primary risk factor of grazing for this species applies to several other species in the 

group.

Model Description

Source habitat— 

This species prefers canyons and draws, dense willows along streams, second-growth 

woodland habitat that can be created by fire or logging, including dead or fallen 

trees, brushy areas near low moist ground, and brushy dry hillsides not far from 

water (Terres 1980). It requires dense undergrowth and moderate cover for breeding 

(Morrison and Meslow 1983). Morrison (1981) described breeding habitat in coniferous or deciduous forests as having 74.2 and 60.1 percent total cover, composed of 

63.8 and 44.8 percent shrubs, 3.7 and 7.7 percent coniferous species, and 6.7 and 7.6 

percent deciduous species, respectively. In eastern Oregon, MacGillivray’s warblers 

breed in dense willow thickets around springs and stream bottoms (Gabrielson and 

Jewett 1940). This warbler does not nest in sagebrush habitats (Gilligan et al. 1994). In 

the Cascade Range of Washington, Lehmkuhl et al. (2007) reported this species having a strong association with riparian habitats in dry forest types. 

Source habitat is defined in this analysis as areas with a 330-ft buffer on perennial streams (i.e., stream orders 3 through 8) that have >70 percent shrub cover 

using gradient nearest neighbor (GNN) vegetation data set. In addition, we included 

meadow habitat from the cover-type map and palustrine, scrub-shrub (PSS) and 

palustrine forested wetlands (PFO) from the National Wetland Inventory (Cowardin 

et al. 1979).

Fire-suppression 

efforts in eastern 

Washington dry forests 

have resulted in forest 

structure that is 

apparently not suitable 

as a breeding habitat 

owing to reductions 

in insect populations 

and limited space for 

foraging activity.
135

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Human developments (e.g., those from dams, diversions, agriculture conversion, stream channelization, road construction) have permanently altered millions 

of acres of wetland habitat. Based on these findings, we made a conservative 

estimate that source habitat for MacGillivray’s warbler in the assessment area was 

about 70 percent of the historical amount. Applying these assumptions, we considered the current departure of wetland habitat (-30 percent) to be at the -2 class.

Grazing— 

MacGillivray’s warbler is a Neotropical migrant known to be negatively affected 

by livestock grazing. In three separate studies, this species was absent from heavily grazed or browsed areas but was found on nearby ungrazed or lightly grazed 

comparison plots (Berger et al. 2001, Medin and Clary 1991, Mosconi and Hutto 

1982). The negative impact was considered to be a result of alteration of important 

vegetation structure and composition, as well as negative impacts on water quality 

or water regimes that affect vegetation (Zwartjes et al. 2005). 

The presence of domestic grazing was used to assess the quantity and quality of 

shrub habitat considered important for MacGillivray’s warbler. We categorized the 

amount of source habitat in an active grazing allotment using 10 percent increments 

from 0 to 100 percent, with increasing poorer shrub habitat as the proportion of 

source habitat in an active allotment increased (fig. 41).

Invasive species— 

MacGillivray’s warblers are reported to be occasionally parasitized by brown-headed cowbird (Molothrus ater), but extent and vulnerability are unknown (Pitocchelli 

1995). Other research found that these warblers may be heavily parasitized by 

cowbirds in areas near agriculture, but have also been found breeding in smaller 

riparian areas far from agriculture (Tewksbury et al. 1999). Though breeding success in these areas has not been sufficiently studied, smaller deciduous riparian 

areas far from agriculture likely provide nesting sites free from cowbird parasitism 

(Tewksbury et al. 1999). 

To assess the effects of nest parasitism by cowbirds, we categorized the percentage (per watershed) of source habitat within 0.62-mi buffer of agricultural lands 

using 10 percent increments from 0 to 100 percent, with increasing poorer habitat 

outcomes as the proportion of source habitat in the buffer increased (fig. 41).

Calculation of historical conditions—

• Departure of source habitat: Class 1

• Livestock grazing: 0 percent

• Nest parasitism: 0 percent
136

GENERAL TECHNICAL REPORT PNW-GTR-907

The relative sensitivity of WI values to the variables used in the model for 

MacGillivray’s warbler are shown in table 32.

Surrogate Species Assessment Results

Watershed scores— 

Owing to presumed habitat loss in all watersheds, the WI values in all watersheds 

was currently moderate or low (<2.0, fig. 42). Watersheds that had the most source 

habitat both currently and historically were the Upper Pend Oreille, Stehekin, 

Ross Lake, and White-Little Wenatchee (all >12,360 ac). Except for the Upper 

Pend Oreille, nearly all the habitat for MacGillivray’s warbler is on Forest Servicemanaged lands.

Although nearly 50 percent of the watersheds (n = 33, 46 percent) had <10 percent of the source habitat in an active grazing allotment, 8 percent had >50 percent 

(n = 16) of the source habitat in an active grazing allotment. These watersheds 

with >50 percent habitat in active grazing allotments had low WI values (<1). As 

described earlier, livestock grazing has been shown to be a negative impact on the 

quality of MacGillivray’s warbler habitat. The negative effect of nest parasitism was 

less of an influence on watershed scores.

Figure 41—Surrogate species assessment model for MacGillivray’s warbler.
137

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 32—Relative sensitivity of 

watershed index values to variables in 

the model for MacGillivray’s warbler

Variable Sensitivity rank

Habitat departure 1

Livestock grazing 2

Nest parasitism 3

Figure 42—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D) 

habitat conditions for McGillivary’s warbler by watershed in the northeast Washington assessment area.
138

GENERAL TECHNICAL REPORT PNW-GTR-907

Although our index of potential negative impacts of nest parasitism (percentage of source habitat within 0.62 mi of agriculture) ranged from 0 to 99 percent, 

the median value for all watersheds was about 10 percent. Fifty percent (n = 36) of 

the watersheds had <10 percent, while 13 percent (n = 9) had >50 percent of their 

habitat near agriculture.

Viability outcome score— 

The VOI model incorporated the weighted WWI scores (described earlier), and a 

habitat distribution index. The WWI scores indicated that the current habitat capability for MacGillivray’s warbler within the assessment area is 51 percent of the 

historical capability. Sixty-four percent (n = 46) of the watersheds had >40 percent 

of the median amount of historical source habitat across all ecoregions. The watersheds with >40 percent were distributed across all five ecoregions. Dispersal across 

the assessment area was not considered an issue for this species owing to its high 

mobility. The resulting viability outcome for MacGillivray’s warbler is primarily C 

(fig. 43), indicating that suitable environments are distributed frequently as patches 

or exist at low abundance. 

Historically, we estimated that 75 percent (n = 54) of the watersheds contained 

>40 percent of the median amount of source habitat and were distributed across 

all five ecoregions, which led to primarily A viability outcome (fig. 43). MacGillivray’s warbler habitat amount and distribution has declined as a result of loss and 

modification of source habitats. 

Figure 43—Current and historical viability outcomes for the MacGillivray’s warbler in the northeast Washington 

assessment area.
139

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Loss of riparian shrub habitat owing to the encroachment of conifers as a 

result of fire suppression.

2. Loss of riparian habitat owing to road construction and other human 

developments.

3. Reduced quality and quantity of shrub habitat owing to the effects of livestock grazing.

Marsh Wren

Introduction

Marsh wrens were chosen as a surrogate species to represent species associated 

with the marsh group of the wetland family. They have been shown to be sensitive to hydrologic change in wetland habitats (Steen et al. 2006, Timmermans et 

al. 2008). Water-level changes and associated reductions in the amount or extent 

of standing water in emergent vegetation affected habitat quality for marsh wrens 

(Meyer 2003, Timmermans et al. 2008, Tozer 2002). Shallow-water species, such 

as marsh wrens, may be more sensitive to habitat suitability changes caused by 

hydrological dynamics than other wetland species (Steen et al. 2006, Timmermans 

et al. 2008). The main risk factors for all species associated with marsh habitat were 

draining, filling, and degradation of marshes; environmental contaminants; and 

predators at nest sites. Marsh wrens were chosen as the surrogate species for this 

group because they have widespread distribution in eastern Washington and their 

risk factors include those of the other species in this group. Marsh wrens range 

across the central portion of the assessment area (Smith et al. 1997). Marsh wrens 

were year-round residents of the assessment area (Kroodsma and Verner 1997); this 

assessment was for nesting habitat.

Model Description

Source habitat— 

Presence and depth of standing water within emergent vegetation was an important 

habitat feature for many marsh birds, including marsh wrens, because it facilitated 

foraging activities, cover for predator avoidance, and often dictated food or nest site 

availability (Kroodsma and Verner 1997, Picman et al. 1993). Cattail marshes with 

interspersed open water >3.3 ft deep were preferred nesting sites for marsh wrens 

(Linz et al. 1996, Manci and Rusch 1988, Ozesmi and Ozesmi 1999, Picman et al. 
140

GENERAL TECHNICAL REPORT PNW-GTR-907

1993, Verner and Engelsen 1970). Leonard and Picman (1986) reported that nests of 

marsh wrens in dense vegetation with deep water were more successful than those 

in shallower water (i.e., means of 36 vs. 52 in). Banner and Schaller (2001) suggested that palustrine, emergent wetlands PEM (Cowardin et al. 1979) were preferred 

habitat for nesting marsh wrens. For this analysis, PEMs, as described and mapped 

through the National Wetlands Inventory (Cowardin et al. 1979), were considered 

source habitat for marsh wrens (fig. 44).

Invasive species— 

Marshes invaded with purple loosestrife have been reported to be less suitable 

as habitat for marsh wrens than marshes with cattails or other natural vegetation 

(Rawinski and Malecki 1984, Whitt et al. 1999). Although it has been suggested 

that the conclusions reached by these studies were equivocal (Anderson 1995, Hagar 

and McCoy 1998), a more recent review (Blossey et al. 2001) confirmed the threat 

of habitat degradation in marshes and other wetlands as a result 

of invasion by purple loosestrife.

Figure 44—Surrogate species assessment model for marsh wren.
141

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

The following classes of purple loosestrife presence in wetlands were used to 

evaluate the effect of the invasion of habitats within the assessment area (fig. 44):

• Zero: Purple loosestrife not present within a watershed

• Low: Purple loosestrife present in <30 percent of wetlands within a 

watershed

• High: Purple loosestrife present in ≥30 percent of wetlands within a 

watershed

Marsh size— 

Birds nesting in the interior of marshes have been reported to be more secure 

from predation (Picman et al. 1993, Richter 1984), indicating that marshes in large 

patches provide more productive habitat than small patches. This was also supported by the finding that marsh wrens suffered more predation when nesting at 

dry sites at the edge of marshes than at sites in the center of marshes (Leonard and 

Picman 1986). Gibbs and Melvin (1990) and Brown and Dinsmore (1986) found that 

marsh wrens preferred larger to small marshes. Although their statistical power was 

low (i.e., 0.73), Benoit and Askins (2002) showed a tendency for marsh wrens to 

prefer large patches (i.e., >250 ac) for nesting. Banner and Schaller (2001) suggested 

that marshes >40 ac were more valuable as habitat for marsh wrens than smaller 

marshes. Sites >460 ft from the edge in cattail marshes were preferred for nesting 

(Ozesmi and Ozesmi 1999). This finding suggests that marshes >40 ac provide progressively more nesting habitat.

The following classes of size of source habitat for marsh wrens were used to 

evaluate the effect of marsh size within the assessment area (fig. 44):

• Small: <40 ac mean size of PEM wetlands within a watershed

• Large: ≥40 ac mean size of PEM wetlands within a watershed

Calculation of historical conditions—

Values of the model variables were set with the following values to estimate historical habitat conditions:

• Departure of source habitat from HRV: 0.5

• Invasive species: Class zero

• Marsh size: Same as current condition

• Current amount of habitat in each watershed was increased by 30 percent.

The relative sensitivity of the WI values to the variables used in the model for 

marsh wren are shown in table 33.
142

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 33—Relative sensitivity of 

watershed index values to variables 

in the model for marsh wren

Variable Sensitivity rank

Habitat departure 1

Marsh size 2

Invasive plants 3

Assessment Results

Watershed scores— 

Historically, 72 percent (n = 52) of the watersheds within the assessment area provided habitat for marsh wrens and other species associated with the marsh group of 

the wetland family. Currently, the same watersheds contained some habitat for this 

species group, although several watersheds have minimal amounts (i.e., <50 ac) 

(fig. 45). Watersheds with the largest amounts of habitat were located in the central, 

eastern, and southern portions of the assessment area. All watersheds with habitat 

had WI scores that were moderate (>1.0 and < 2.0) (fig. 45).

Marsh wrens have been reported to be sensitive to invasion of source habitats 

by purple loosestrife (Rawinski and Malecki 1984, Whitt et al. 1999). All counties 

within the assessment area, except Ferry County, have recorded occurrences of 

purple loosestrife (USDA NRCS 2004). Twelve percent (n = 6) of the watersheds 

had habitat wholly or mostly within Ferry County and were considered free from 

the effects of purple loosestrife for this analysis. Twelve percent (n = 6) of the 

watersheds had habitat immediately adjacent to Ferry County and were considered 

to be in the low invasion category. The remaining 76 percent (n = 40) of the watersheds with habitat were considered to be in the high invasion category.

The size of marshes was thought to be directly related to habitat quality for 

marsh wrens (Banner and Schaller 2001). All watersheds with habitat had >90 

percent of marshes in the small size category.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability for 

marsh wren within the assessment area was 48 percent of the historical capability. 

Dispersal across the assessment area was not considered an issue for this species 

owing to their high mobility. All ecoregions currently contained at least one watershed with >40 percent of the median amount of historical source habitat (median 

was calculated across all watersheds with source habitat). Forty-four percent 
143

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

(n = 32) of the watersheds had >40 percent of the median amount of historical 

source habitat. Under those circumstances, there is a 71 percent probability that the 

current viability outcome for marsh wrens was C, indicating that habitat is patchily 

distributed and in low abundance (fig. 46). Other species associated with the marsh 

group of the wetland family literally have similar outcomes.

Figure 45—Current amount of (A) source habitat (acre), (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for marsh wrens (MAWR) by watrshed in the northeast Washington assessment area (NEWA).
144

GENERAL TECHNICAL REPORT PNW-GTR-907

Historically, dispersal across the assessment area was not considered an issue 

for this species owing to their high mobility. Five of five ecoregions contained at 

least one watershed with >40 percent of the median amount of historical source 

habitat (median was calculated across all watersheds with source habitat). Fortynine percent (n = 35) of the watersheds had >40 percent of the median amount of 

historical source habitat. Under those circumstances, there was a 57 percent probability that the historical viability outcome for marsh wrens was A, and a 27 percent probability that the historical viability outcome for these species was B, 

indicating that habitat was broadly distributed with an abundance of high-quality 

habitat (fig. 46).

In summary, under historical conditions, marsh wrens and other species 

associated with the marsh group of the wetland family were likely well distributed 

throughout the assessment area. Currently, there were likely fewer populations 

occupying lower quality habitat throughout the assessment area.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Loss and degradation of wetland habitats.

2. Negative effects of purple loosestrife invasion in source habitats.

Figure 46—Current and historical viability outcomes for marsh wrens in the northeast Washington 

assessment area.

Marsh wrens and other 

species associated 

with the marsh group 

of the wetland family 

were likely well 

distributed throughout 

the assessment 

area. Currently, there 

were likely fewer 

populations occupying 

lower quality habitat 

throughout the 

assessment area.
145

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Northern Bog Lemming

Introduction

The northern bog lemming was selected as a surrogate species in the boreal forest group. The northern bog lemming is limited to the cold, wet bogs or grass/

forb meadows within or on the edges of the boreal coniferous forest (Groves and 

Yenson 1989, Reichel and Beckstrom 1994, Sallabanks et al. 2001). The watersheds 

that contain known records of the northern bog lemming include the Lower Pend 

Oreille, Middle Pend Orielle, Upper Methow, Lost River, Upper Chewuch, and 

Sinlahekin Creek. Very little is known about the ecological relationships of this 

species (Johnson and Cassidy 1997). 

Owing to the limited distribution of this species within the assessment area, 

a surrogate species assessment model was not developed. However, a qualitative 

assessment of its habitat relationships and general management considerations is 

provided.

Source habitat— 

Bog lemmings are found in sphagnum bogs, wet meadows, moist mixed and coniferous forests; alpine sedge meadows, krummholz spruce-fir forest with dense herbaceous and mossy understory, and mossy streamsides (Clough and Albright 1987, 

Groves and Yenson 1989, Reichel and Beckstrom 1994, Sallabanks et al. 2001).

Risk factors— 

The risk factors that were identified for this species include the fragmentation or 

loss of habitat as a result of road construction and mortality associated with winter 

recreational activities causing snow compaction. Snow compaction has been cited 

to cause mortality and to present barriers to small mammals that move in subnivean 

spaces, such as bog lemmings (Layser and Burke 1973, Schmid 1972). Layser and 

Burke (1973) have also identified heavy grazing and loss of habitats owing to impoundments as additional risk factors.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Wetlands and alpine meadows provide source habitat for bog lemmings.

2. Areas of sphagnum or other fen/bog moss mats or associated riparian areas 

could provide corridors for interpatch movements. 
146

GENERAL TECHNICAL REPORT PNW-GTR-907

3. Domestic livestock grazing in drainages with unsurveyed moss mats present or known lemming populations may reduce habitat quality for bog 

lemmings. 

4. Snow compaction may reduce subnivean habitats and movements during 

winter.

Northern goshawk

Introduction

The northern goshawk was selected as a surrogate species to represent the forest 

mosaic and all forest communities medium- and large-tree family group. Risk 

factors that the goshawk represents include the potential for human disturbance to 

disrupt breeding activities (Reynolds et al. 1992) and the effects of forest roads in 

habitat loss and fragmentation (Wisdom et al. 2000). Goshawks are widely distributed across the forested portions of the assessment area (Smith et al. 1997), and this 

assessment considered year-round habitats. 

Model Description

Source habitat— 

The northern goshawk uses a complex mosaic of landscape conditions to meet various life history requirements for nesting, postfledgling, and foraging (Desimone 

and Hays 2003, Reynolds et al. 1992). Goshawk nesting habitat in eastern 

Washington and Oregon was generally composed of mature and older forests 

(McGrath et al. 2003). Nest stands were typically composed of a relatively high 

number of large trees, high canopy closure (>50 percent), multiple canopy layers, 

and a relatively high number of snags and down wood (McGrath et al. 2003). 

Postfledgling areas contain the nest area(s) and are areas of concentrated use by 

adult females and developing juveniles after fledgling and prior to natal dispersal 

(Kennedy et al. 1994, Reynolds et al. 1992). Postfledgling areas surround and 

include the nesting area and provide foraging opportunities for adult females and 

fledgling goshawks, as well as cover for fledglings (Kennedy et al. 1994, Reynolds 

et al. 1992). Postfledgling areas in eastern Washington and Oregon were composed 

largely of structurally complex late-successional forests (McGrath et al. 2003). 

Changes in forest structure owing to fire exclusion within the dry forest cover 

types may seem to increase the availability of source habitat for the goshawk. However, they may not be as valuable as the more open habitats they replaced because 

the ingrowth of small trees may obstruct flight during foraging, suppress growth of 

large trees needed for nesting, and reduce the growth of herbaceous understory that 

provides habitat for prey (Reynolds et al. 1992).
147

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

We modeled goshawk source habitat using the following variables that were 

available in our GIS data layers (fig. 47):

• Forest types: Dry forest, mesic forest, cold-moist forest

• Tree size: >15 in QMD

• Layers: Single/multistory 

• Canopy closure: >50 percent

Late-successional forest— 

Goshawks forage in a variety of forest types; however, several studies have shown 

the importance of mid- to late-successional forests as foraging habitat for goshawks 

(Austin 1993, Beier and Drennen 1997, Bright-Smith and Mannan 1994, Daw and 

DeStefano 2001, Desimone and DeStefano 2005, Drennan and Beier 2003, Finn et 

al. 2002a, 2002b; Hargis et al. 1994, Patla 1997). Results from Beier and Drennen 

(1997) supported the hypothesis that goshawk morphology and behavior are adapted for hunting in moderately dense, mature forests, and that prey availability (as 

determined by the occurrence of favorable vegetation structure) is more important 

than prey density in habitat selection. Salafsky and Reynolds (2005) showed that 

Figure 47—Surrogate species assessment model for northern goshawk.
148

GENERAL TECHNICAL REPORT PNW-GTR-907

goshawk productivity was related to prey availability, especially critical prey species. Taken together, these studies show the importance of habitat structure to goshawk foraging behavior and productivity.

Because of the importance of late-successional forests in many of the life 

history stages of the goshawk, we chose to map late-successional forests as a factor 

that influenced the quality of source habitat (fig. 47). We modeled late-successional 

forest habitats using the following variables that were available in our GIS data 

layers:

• Forest types: Dry forest, mesic forest, cold-moist forest

• Tree size: >20 in QMD

• Layers: Single/multistory

• Canopy closure: >50 percent

We then categorized the amount of source habitat composed of late-successional forest as follows (fig. 47):

• Zero: Late-successional forest in source habitat

• Low: >0 to 20 percent of the source habitat in late-successional forest

• Moderate: >20 to 50 percent of the source habitat in late-successional forest

• High: >50 percent of the source habitat in late-successional forest

Habitat effectiveness— 

Human disturbances at goshawk nest sites have been suspected as a cause of nest 

abandonment (Reynolds et al. 1992). In addition, roads and trails may facilitate access for falconers to remove young from nests (Erdman et al. 1998). Wisdom et al. 

(2000) identified habitat fragmentation or habitat loss as a forest road-associated 

factor for goshawks. In addition, roads may increase the likelihood of the removal 

of snags for safety and firewood collection, which could have negative effects on 

the prey base for goshawks (Wisdom et al. 2000). However, Grubb et al. (1998) reported that vehicle traffic with a noise level of <54 decibels on roads >1,320 ft from 

nest sites did not result in discernible behavioral response by goshawks in forested 

habitats.

Because of these potential influences of forest roads on goshawk source habitat, 

we used the late-successional forest habitat disturbance index described in Gaines 

et al. (2003). This index buffers open roads and motorized trails that occur within 

source habitat by 660 ft on each side, and nonmotorized trails that occur within 

source habitat by 330 ft on each side. The amount of source habitat that was influenced by human activities was then categorized as follows for each watershed (fig. 47):
149

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

• Low habitat effectiveness: <50 percent of the source habitat outside a zone of 

influence

• Moderate habitat effectiveness: 50 to 70 percent of the source habitat outside a zone of influence

• High habitat effectiveness: >70 percent of the source habitat outside a zone 

of influence

Calculation of historical conditions—

• Departure of source habitat: Departure class 1

• Late-successional habitat: High

• Habitat effectiveness: High

The relative sensitivity of the WI values to the variables used in the model for 

northern goshawk are shown in table 34.

Surrogate species model evaluation— 

We compared the mean WI value derived from 674 points with documented occurrences of northern goshawks to the mean WI value derived from 674 random points. 

The mean WI for the occurrence points (1.72) was significantly higher (t = 1.96, P 

<0.0001) than the mean derived from the random points (1.56) indicating that our 

model successfully identified watersheds with suitable environments for northern 

goshawks.

Assessment Results

Watershed scores— 

Thirty-one (43 percent) of the watersheds had WI scores that were high (>2.0). 

Eight (11 percent) of the watersheds had moderate scores (1.0 to 2.0). Our assessment showed that the departure in the amount of source habitat from the expected 

historical median amount was the variable with the most influence on the northern 

goshawk watershed scores.

Table 34—Relative sensitivity of 

watershed index values to variables in 

the model for northern goshawk

Model variables

Order of variable 

weighting

Source habitat 1

Late-successional forest 2

Habitat effectiveness 3
150

GENERAL TECHNICAL REPORT PNW-GTR-907

We found that the amount of source habitat in 15 percent (n = 11) of the 

watersheds was above the historical median of source habitat, 35 percent (n = 25) 

were near the historical median, and 50 percent (n = 36) were below the historical median. The lack of big tree structure, particularly in the watersheds located 

on the eastern portion of the Okanogan-Wenatchee National Forest and most of 

the Colville National Forest, limited the availability of source habitat for northern 

goshawks in these areas. This finding is similar to that reported in Wisdom et al. 

(2000) where strongly negative trends in the amount of source habitat for goshawk 

occurred in the northern portion of the Northern Cascade Range and throughout the 

Northern Glaciated Mountain ERUs.

Watersheds with the most source habitat (>49,420 ac) included the Stehekin, 

Ross Lake, White-Little Wenatchee River, Upper Tieton River, and Little Naches 

Rivers. Watersheds with the least amount of source habitat (<1,230 ac) included the 

Middle Yakima River, Upper Columbia-Swamp Creek, and Upper Little Spokane 

River. 

The amount of source habitat that was in a late-successional stage was low 

overall. Currently, 21 percent (n = 15) of the watersheds were rated as having a high 

(>50 percent of the source habitat) amount of late-successional forest habitat, 12 

percent (n = 9) had a moderate amount (30 to 50 percent), 64 percent (n = 46) low 

(>0 to <30 percent), and 3 percent (n = 2) no late-successional forest habitat.

Habitat effectiveness was indexed by buffering the amount of source habitat 

adjacent to roads (Gaines et al. 2003). Habitat effectiveness for goshawks was 

considered to be high within 54 percent (n = 39) of the watersheds, moderate in 

42 percent (n = 30), and low in 4 percent (n = 3). 

Viability outcome scores— 

The VOI model incorporated the WWI scores and a habitat distribution index. The 

WWI provides a relative measure across watersheds of the potential capability of 

the watershed to contribute to the viability of the surrogate species. The current 

WWI across the assessment area was 68 percent of the historical WWI. 

Currently, 54 percent (n = 39) of the watersheds are above the 40 percent 

threshold of the historical median amount of source habitat, whereas historically, 

88 percent (n = 63) were above this minimum habitat amount. Currently, the 

watersheds with >40 percent of the historical median amount of source habitat were 

distributed across all of the five ecoregions, as was the case historically. Dispersal 

across the assessment area was not considered an issue for this species (fig. 48). 
151

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Under current conditions, there is a 28 percent probability that the viability 

outcome for goshawks across the assessment area is A, and a 54 percent probability 

of outcome B. This indicates that suitable environments for the northern goshawk 

are broadly distributed and of relatively high abundance, but there are gaps where 

suitable environments are absent or only present in low abundance (fig. 48). These 

gaps are typically not large enough to prevent species from interacting as a metapopulation. Historically, the viability outcome had an 80.8 percent probability of A, 

where suitable environments were more broadly distributed or of high abundance. 

In addition, the suitable environments were better connected, allowing for interspecific interactions. A reduction in the availability of suitable environments for 

the northern goshawk may have occurred in the assessment area compared to the 

historical distribution and condition of their habitats.

Historically, northern goshawks and other species in the forest mosaic/all forest 

communities medium-to-large old-tree group/family were likely well distributed 

with viable populations across the assessment area. Wisdom et al. (2000) assessed 

viability for the northern goshawk across the Columbia Basin, at a broader scale 

and coarser resolution, and reported similar results. 

Figure 48—Current and historical viability outcomes for the northern goshawk in the northeast Washington 

assessment area.
152

GENERAL TECHNICAL REPORT PNW-GTR-907

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Reduction in the amount of source habitat, particularly within the eastern 

portion of the Okanogan-Wenatchee National Forest and across much of the 

Colville National Forest.

2. Declines in the densities of large-diameter (>21 in) trees and snags from 

historical to current levels (Hann et al. 1997, Harrod et al. 1999, Hessburg 

et al. 1999a), which are important components of habitat for the species in 

this group.

3. Potential loss of snag and down log habitat as a result of high open road 

densities.

4. Fire exclusion within much of the dry forest cover types may have reduced 

the sustainability of these habitats and has resulted in increased susceptibility to stand-replacing fires (Everett et al. 2000, Hessburg et al. 1999a, 

McGrath et al. 2003, Townsley et al. 2004).

5. Limited information on the effects of dry forest restoration treatments on 

goshawk habitat use and productivity.

Northern Harrier

Introduction

The northern harrier was selected as a surrogate species for the grasslands group 

because it is a widely distributed species across grasslands in the assessment area. 

In addition, this species will also be found in wetter grassy and marsh areas, similar 

to the short-eared owl, another member of the group. All species in this group share 

human disturbance as a risk factor. Though some harriers may remain in the area 

during the winter, we primarily evaluated breeding habitat. 

Model Description

Source habitat— 

Northern harriers prefer relatively open grassland habitats characterized by 

tall, dense vegetation and abundant residual vegetation (Apfelbaum and Seelbach 

1983, Duebbert and Lokemoen 1977, Hamerstrom and Kopeny 1981, Kantrud 

and Higgins 1992). They are associated with wet or dry grasslands, fresh to 

alkali wetlands, lightly grazed pastures, croplands, fallow fields, old fields, and 

shrubby areas (Apfelbaum and Seelbach 1983, Evans 1982, Faanes 1983, Kantrud 
153

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

and Higgins 1992, Linner 1980, MacWhirter and Bildstein 1996, Prescott et al. 

1995, Prescott 1997, Stewart 1975, Stewart and Kantrud 1965). Although cropland 

and fallow fields were used for nesting, most nests were found in undisturbed wetlands or grasslands dominated by dense vegetation (Apfelbaum and Seelbach 1983, 

Duebbert and Lokemoen 1977, Kantrud and Higgins 1992). Nest success may have 

been lower in cropland and fallow fields than in undisturbed areas (Kibbe 1975).

Northern harriers nested on the ground or over water on platforms of vegetation in stands of cattail (Typha spp.) or other emergent vegetation (Bent 1961, Clark 

1972, MacWhirter and Bildstein 1996, Saunders 1913, Sealy 1967, Stewart 1975). 

Ground nests were well concealed by tall, dense vegetation, including living and 

residual grasses and forbs, or low shrubs, and are located in undisturbed areas with 

much residual cover (Duebbert and Lokemoen 1977, Hamerstrom and Kopeny 1981, 

Hecht 1951, Herkert et al. 1999, Kantrud and Higgins 1992).

Nests in wet sites may have an advantage in that fewer predators have access 

to them (Sealy 1967, Simmons and Smith 1985). In Alberta, northern harriers were 

more abundant in large (>20 ac) fresh wetlands than in small (<2.5 ac) fresh wetlands (Prescott et al. 1995). 

Northern harriers had large territories; in Idaho, home ranges averaged 3,880 ac 

for males and 280 ac for females (Martin 1987). In North Dakota, breeding harriers were found only in grassland patches >250 ac and were encountered in large 

patches more than expected (Johnson and Igle 2001). All occupied patches exceeded 

250 ac. In contrast, Herkert et al. (1999) suggested that harriers may respond more 

strongly to total amount of grassland within the landscape rather than to sizes of 

individual grassland tracts. 

For this assessment, we identified grassland, and meadows (wet and dry 

meadow) cover types in the shrub-steppe potential vegetation type as source habitat 

for this species. We included PEM and PSS habitats as identified in the National 

Wetlands Inventory data set (Cowardin et al. 1979). In addition, we described 

source habitat as areas with <20 percent slope and patches of habitat >1 ac. Only 

watersheds with >120 ac of habitat historically were included in the analysis. Source 

habitat was identified as (fig. 49):

• Potential vegetation types: Shrub-steppe

• Cover types: Grassland, wet meadows, dry meadows

• National Wetlands Inventory: PEM and PSS 

• Slope: <20 percent
154

GENERAL TECHNICAL REPORT PNW-GTR-907

Grazing— 

Overgrazing, the advent of larger crop fields, and fewer fence rows, together with 

the widespread use of insecticides and rodenticides, have reduced the availability 

of prey for northern harriers and thus the amount of suitable habitat for this species 

(Duebbert and Lokemoen 1977, Hamerstrom 1986). In the Great Plains, Southwest, 

and U.S. intermountain West, northern harriers have been found to use livestockgrazed grasslands less than ungrazed areas (Bildstein and Gollop 1988, Bock et 

al. 1993, Linner 1980). Northern harriers preferred idle areas to grazed areas in 

North Dakota (Sedivec 1994). Northern harriers do not use heavily grazed habitats 

(Berkey et al. 1993, Bock et al. 1993, Stewart 1975) but may use lightly to moderately grazed grasslands (Bock et al. 1993, Kantrud and Kologiski 1982). In North 

Dakota, northern harriers had significantly higher nesting density on ungrazed 

Figure 49—Surrogate species assessment model for northern harriers.
155

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

areas than areas grazed season-long or under a twice-over grazing rotation schedule (Messmer 1990, Sedivec 1994). In aspen parkland of Alberta, northern harriers 

were most abundant in deferred grazed (grazed after 15 July) mixed grass, but were 

absent from continuously grazed mixed grass and deferred or continuously grazed 

tame pasture (Prescott et al. 1995).

To account for possible impacts of livestock grazing on habitat, we categorized 

the amount of source habitat in an active grazing allotment using 10 percent increments from 0 to 100 percent, with increasing poorer habitat outcomes as the proportion of source habitat in an active allotment increased (fig. 49).

Habitat effectiveness— 

Nesting harriers are sensitive to human disturbance especially from the prelaying 

and egg-laying stages up to hatching (Fyfe and Olendorff 1976, Hamerstrom 1969). 

Predation of harrier young has occurred when predators followed humans to nests 

(Toland 1985, Watson 1977). Harriers will leave wintering areas with potentially 

suitable nesting habitat presumably, in part, owing to heavy use by humans 

(Serrentino 1992). 

Because of the potential effects of humans on harriers, we mapped 660-ft buffers 

on each side of open roads and motorized trails that occurred within source habitat. 

We also mapped 330-ft buffers on each side of nonmotorized trails that occurred 

within source habitat. The amount of source habitat that was influenced by human 

activities (within the buffers) was then categorized as follows for each watershed (fig. 

49):

• Zero habitat effectiveness: 100 percent of the source habitat inside the zone 

of influence

• Low habitat effectiveness: <50 percent of the source habitat outside a zone 

of influence

• Moderate habitat effectiveness: 50 to 70 percent of the source habitat outside a zone of influence

• High habitat effectiveness: >70 percent of the source habitat outside a zone 

of influence

Historical inputs for surrogate species assessment model—

• Departure of source habitat: Class 1

• Grazing: 0 percent

• Habitat effectiveness: Zero

The relative sensitivity of WI values to the variables used in the model for the 

northern harrier are shown in table 35.
156

GENERAL TECHNICAL REPORT PNW-GTR-907

Assessment Results

Watershed scores— 

Thirty-six watersheds were estimated to have >120 ac of source habitat historically 

and were included in our analysis. Three watersheds contained >24,700 ac of source 

habitat: Columbia River-Lynch Coulee, Lower Okanogan River, and Okanogan and 

River-Omak Creek (fig. 50). Very little source habitat for northern harriers existed 

on National Forest System lands. While the Columbia River-Lynch Coulee watershed contains more than 8,650 ac of source habitat on National Forest System lands, 

all other watersheds contained less than 300 ac of source habitat on National Forest 

System lands. 

Although seven watersheds (18 percent) had <10 percent departure from 

historical habitat conditions, the remaining watersheds lost >25 percent of historical source habitat for harriers (fig. 50). Ten watersheds (28 percent) were found to 

have >60 percent losses in sources habitat. Other research has shown that extensive 

draining of wetlands, monotypic farming, and reforestation of farmlands have led 

to a decline in habitat and population sizes of northern harriers (MacWhirter and 

Bildstein 1996, Serrentino 1992, USDI FWS 1987).

The overall loss of habitat led to overall low WI scores (fig. 50). Sixty-four 

percent (n = 23) of watersheds had WI scores of low (<1.0); 28 percent (n = 10) had 

a score of moderate (>1.0 to <2.0); and the remaining 8 percent (n = 3) had a high 

score (> 2.0). The watersheds that had a high WI score were Salmon Creek and 

Sinlahekin. 

The watersheds that had a WI between 1.0 and 2.0 had generally either a <15 

percent reduction in habitat and higher levels (>40 percent) of grazing or 15 to 30 

percent loss in habitat and lower levels of grazing (<10 percent). Watersheds with 

the highest WI values generally had <15 percent loss in habitat and lower levels of 

grazing (<15 percent). Habitat effectiveness was low in most watersheds (55 percent, 

n = 20), which also contributed to lower WI values.

Table 35—Relative sensitivity of 

watershed index values to variables 

in the model for northern harriers

Variable Sensitivity rank

Habitat departure 1

Grazing 2

Habitat effectiveness 3
157

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Figure 50—Current amount of (A) source habitat (acres), (B) habitat departure, (C) watershed index, and (D) 

habitat condition class for northern harriers by watershed in the northeast Washington assessment area.
158

GENERAL TECHNICAL REPORT PNW-GTR-907

Viability outcome— 

The VOI model incorporated the WWI scores (described earlier), and a habitat distribution index. The comparison of the current WWI to the historical WWI showed 

that current habitat was at 50 percent of historical capability. Currently, 50 percent 

of the watersheds have source habitats >40 percent of the historical median, which 

is a decline from 67 percent historically. Currently, the viability outcome for harriers 

across the assessment area is primarily a C outcome indicating that suitable environments are distributed frequently as patches and/or exist at low abundance (fig. 51).

The current outcome is a decline from an estimated A outcome historically 

(fig. 51). Historically, we estimated that 67 percent (n = 24) dispersed across all 

five ecoregions contained >40 percent of the historical median amount of source 

habitat leading to primarily an A outcome where habitats were abundant and well 

distributed. In summary, the northern harrier and other species associated with the 

grassland group likely have experienced a loss in the abundance and distribution of 

suitable environments across the assessment area.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Loss of grassland and wetland habitat because of conversion to agricultural 

and other human developments.

2. Degradation of grassland and wetland habitat through extensive livestock 

grazing. 

3. Adverse effects of human disturbance.

Peregrine Falcon

Introduction

The peregrine falcon was selected as a surrogate species for the habitat generalist/

cliff group because of their association with large cliff habitats as compared to the 

other species in the group. Within the assessment area, the known peregrine falcon 

nest sites occur on the Naches, Wenatchee River, and Methow Valley Ranger Districts. However, suitable nesting habitat occurs on both the Colville and OkanoganWenatchee National Forests. The availability of nesting habitat (e.g., suitable cliff 

structures) may have changed little from what was available historically (Hayes and 

Buchanan 2002); however, other factors, such as availability of foraging habitat and 

habitat effectiveness, have changed. The occurrence of peregrine falcons within the 

assessment area during the winter is considered rare (Hayes and Buchanan 2002), 

thus this assessment addresses breeding habitats.

In summary, the 

northern harrier 

and other species 

associated with the 

grassland group likely 

have experienced a 

loss in the abundance 

and distribution of 

suitable environments 

across the assessment 

area.
159

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Model Description

Source habitat— 

The presence of prominent cliffs is the most common habitat characteristic of peregrine falcon nesting territories (Hayes and Buchanan 2002, Hays and Milner 1999). 

Prominent cliffs function as both nesting and perching sites, and provide unobstructed views of the surrounding landscape (Hayes and Buchanan 2002, Ratcliffe 

1993). Nest site suitability requires the presence of ledges that are essentially inaccessible to mammalian predators, that provide protection from the elements, and 

that are dry (Campbell et al. 1990, Johnsgard 1990). A source of water, such as a 

river, lake, marsh, or marine waters is typically in proximity to the nest site and 

likely is associated with an adequate prey base of small- to medium-sized birds 

(Cade 1982, Johnsgard 1990).

On average, peregrine falcon eyries were about 200 ft from a fresh water 

source in Washington (Hayes and Buchanan 2002). This study reported only a 

few sites more than 1,000 ft from a creek or a body of water >3 ac (Hayes and 

Buchanan 2002).

To model the availability of source habitat for the peregrine falcon, we identified both nesting and foraging habitats. To identify nesting habitat, we used a 

digital elevation model to identify areas that were >38 degrees, which corresponded 

well with cliff structures. To identify the most prominent features, a minimum size 

of ≥5 ac was used. This allowed us to distinguish the prominent cliff structures 

from the smaller cliffs that were unlikely to provide nesting habitat (Hayes and 

Figure 51—Current and historical viability outcomes for northern harriers in the northeast Washington assessment area.
160

GENERAL TECHNICAL REPORT PNW-GTR-907

Buchanan 2002). Finally, we used an elevation cutoff of <3,300-ft elevation in order 

to screen out high-elevation cliff structures that would likely be unavailable to peregrine falcon for nesting owing to the presence of persistent spring snow. Peregrine 

eyries in eastern Washington occur between 666 to 1,860 ft in elevation (Hayes and 

Buchanan 2002).

We assumed that the amount of available nesting habitat had not changed 

from historical to current, thus we used the amount of nesting habitat within the 

watershed as a measure of habitat quality (e.g., the more the better). We categorized 

the amount of nesting habitat as follows (fig. 52):

• Zero: <10 ac of nesting habitat

• Low source habitat: >10 ac but less than the median of nesting habitat 

across all watersheds

• High source habitat: Less than the median of nesting habitat across all 

watersheds

We also assessed the amount of foraging habitat within each watershed (fig. 

52). Foraging habitat was defined as any water body ≥3 ac (Hayes and Buchanan 

2002). We did not assess the proximity of nesting and foraging habitat as described 

in Hayes and Buchanan (2002) because we assumed each watershed was small 

enough and peregrine falcons mobile enough that they could forage anywhere in 

the watershed. We used the following categories to assess the amount of foraging 

habitat for each watershed (fig. 52):

• Low: <10 ac of foraging habitat 

• Moderate: 10 ac to median across all watersheds

• High: Greater than median of all watersheds 

Habitat effectiveness— 

Human activities have been documented to cause disturbance to nesting peregrine falcons (Holthuijzen et al. 1990, Lanier and Joseph 1989, Windsor 1975). Several authors 

have recommended 2,625-ft buffers on nest sites to reduce the potential effects of 

human disturbances on nesting peregrine falcons (Hays and Milner 1999, Richardson 

and Miller 1997). We assessed the potential for human disturbance to affect nesting habitat using the peregrine falcon nesting habitat disturbance index described in 

Gaines et al. (2003). We mapped 2,625-ft buffers on each side of open roads and trails 

to delineate zones of influence and then overlaid this with our map of source habitat. 
161

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

We used the following categories to assess the potential effects of human

disturbance on peregrine falcon habitat effectiveness for each watershed (fig. 52): 

• Low habitat effectiveness: <25 percent of the source habitat outside a zone of 

influence

• Moderate habitat effectiveness: 25 to 50 percent of the source habitat outside a zone of influence

• High habitat effectiveness: >50 percent of the source habitat outside a zone 

of influence

Calculation of historical conditions— 

Source habitat: Current habitat amount—habitat departure class 1

Nesting habitat amount: Based on the current amount

Foraging habitat amount: Based on the current amount

Habitat effectiveness: High

The relative sensitivity of WI values to variables used in the peregrine falcon 

model are shown in table 36.

Figure 52—Surrogate species assessment model for the peregrine falcon.
162

GENERAL TECHNICAL REPORT PNW-GTR-907

Model Evaluation

We compared the mean WI value from 33 points of known occurrences of peregrine falcon nests with an equal number of random points. The mean WI for the 

occurrence points (1.89) was significantly higher (t = 2.00, P = 0.004) than the mean 

from the random points (1.33), indicating that our model successfully identified 

suitable environments for peregrine falcons. 

Assessment Results

Watershed scores— 

Of the 50 watersheds that had source habitat for the peregrine falcon, 64 percent 

(n = 32) had high (>2.0) WI scores, and 28 percent (n = 14) had moderate (1.5 to 

2.0) scores (fig. 53). Watersheds with the greatest amount of source habitat (>370 ac) 

included Ross Lake, Wenatchee River, Upper Lake Chelan, Columbia River-Lynch 

Coulee, and Lower Lake Chelan (fig. 53). Because we assumed that there was no 

departure in the amount of historical source habitat, changes in WI from the historical median were largely related to changes in habitat effectiveness.

The distribution of scores for nesting habitat included 37 percent (n = 19) of the 

watersheds with a low score, none with a moderate score, and 63 percent (n = 32) 

with a high score. Fifty-three percent (n = 27) of the watersheds had a low score for 

foraging habitat, 41 percent (n = 21) with a moderate score, and 6 percent (n = 3) 

with a high score.

Of the watersheds that contained source habitat for peregrine falcons, 57 

percent (n = 29) had a low level of habitat effectiveness based on the proximity of 

source habitats to potential human activities. In addition, 33 percent (n = 33) of the 

watersheds had a moderate level of habitat effectiveness, and only 10 percent (n = 5) 

had a high level of habitat effectiveness. 

Table 36—Relative sensitivity of 

watershed index values to variables in 

the model for the peregrine falcon

Model variables

Order of variable 

weighting

Source habitat 1

Nesting habitat amount 2

Foraging habitat amount 3

Habitat effectiveness 4
163

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Figure 53—Current amount of (A) source habitat (acres), (B) watershed index, and (C) habitat condition class for peregrine falcon 

(PEFA) by watershed in the northeast Washington assessment area (NEWA).
164

GENERAL TECHNICAL REPORT PNW-GTR-907

Viability outcome score— 

The VOI model incorporated the WWI scores (described earlier) and a habitat distribution index. The WWI scores indicated that the current habitat capability across 

the assessment area was about 79 percent of the historical capability. This largely 

had to do with the effects of human activities in source habitat for peregrine falcons. The median amount of nesting habitat was 51.4 ac (across all watersheds with 

at least 2.5 ac of nesting habitat). Currently, 76 percent of the watersheds had habitat amounts that were >40 percent of the historical median, and these watersheds 

were distributed across all of the ecoregions.

Currently, there is a 32 percent probability that the viability outcome for the 

peregrine falcon is A, and a 56 percent probability of B, which indicates that suitable environments for peregrine falcons are broadly distributed and of relatively 

high abundance, but there are gaps where suitable environments are absent or only 

present in low abundance (fig. 54). These gaps are typically not large enough to 

prevent the species from interacting as a metapopulation. Historically, there was 

a 76 percent probability of a viability outcome of A where suitable environments 

were more broadly distributed or of high abundance (fig. 54). In addition, the suitable environments were better connected, allowing for interspecific interactions. 

A reduction in the availability of high-quality habitats for peregrine falcons, and 

likely other species in the group, appears to have occurred in the assessment area 

compared to the historical distribution and condition of their habitats. 

Figure 54—Current and historical viability outcomes for the peregrine falcon in the northeast Washington 

assessment area.
165

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Management Considerations

The following issue was identified during this assessment and from the published 

literature for consideration by managers:

1. The effects of disturbance from human activities within source habitats.

Pileated Woodpecker

Introduction

The pileated woodpecker was chosen as a surrogate species to represent species of 

conservation concern associated with medium-large trees/cool/moist forests group. 

This species also prefers areas with high densities of large snags and logs for foraging, roosting and nesting, as do many of the other species in this group and family. 

This species is well distributed across the assessment area year round.

Model Description

Source habitat— 

Pileated woodpeckers prefer late-successional stages of coniferous or deciduous forest, but also use younger forests that have scattered, large, dead trees (Bull 

and Jackson 1995, Bull et al. 2007). In northeastern Oregon, pileated woodpeckers selected unlogged stands of old-growth grand fir (Abies grandis) with closed 

canopies (Bull and Holthausen 1993) and in some cases open stands with high 

densities of large snags and logs (Bull et al. 2007). These woodpeckers are rarely 

found in stands of pure ponderosa pine (Bull and Holthausen 1993). They will use 

Engelmann spruce at high elevation if big trees are present. In western Oregon, 

pileated woodpecker densities are greater in forests >80 years old than in younger 

forests (Nelson 1988). Their association with late-seral stages stems from their use 

of large-diameter snags or living trees with decay for nest and roost sites, large-diameter trees and logs for foraging on ants and other arthropods, and a dense canopy 

to provide cover from predators (Bull 2003b).

In the Coast Range, mature stands (>70 years) were selected by pileated woodpeckers, and younger stands were avoided for foraging (Mellen 1987). Mannan 

(1984) reported 44 percent of the foraging occurred in dead trees, 36 percent on 

downed logs, and the remainder in other substrates. Results of foraging location 

were similar in northeastern Oregon (Bull and Holthausen 1993). 
166

GENERAL TECHNICAL REPORT PNW-GTR-907

We described source habitat for this species as (fig. 55):

• Potential vegetation: Dry, mesic or cold-moist 

• Cover types: All forested except lodgepole pine and ponderosa pine

• Tree size and structure: >15 in QMD, >40 percent canopy closure, singleand multstory

Snag density— 

Pileated woodpecker nest cavities are quite large (mean diameter of 8 in and depth 

of 22 in) and are excavated at an average height of 50 ft above the ground, so nest 

trees must have a girth large enough to contain nest cavities at this height (Bull 

1987). Of 105 nest trees located in northeastern Oregon, 75 percent were in ponderosa pine, 25 percent in western larch, and 2 percent in grand fir; the mean d.b.h. 

was 33 in (Bull 1987). In western Oregon, 73 percent of nest trees were Douglasfir (Pseudosuga menziesii), and nest trees averaged 27 in d.b.h. (Mellen 1987). In 

northwest Montana, most of 54 nest trees were large western larch (Larix occidenatalis), and nest trees averaged 29.5 in d.b.h. (McClelland 1979).

Figure 55—Surrogate species assessment model for pileated woodpecker.
167

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

In northeastern Oregon, pileated woodpecker roosts were typically located in 

a live or dead grand fir with a mean d.b.h. of 28 in (Bull et al. 1992). In the Coast 

Range, Douglas-fir, red alder, western redcedar, and big-leaf maple contained roosts 

(Mellen 1987).

Timber harvest has had a negative effect on habitat for this woodpecker (Bull 

2003b, Bull et al. 2007). Removal of large-diameter, live and dead trees, down 

woody material, and forest canopy eliminates nest and roost sites, foraging habitat, 

and protective cover. In addition, prescribed fire may eliminate or reduce the 

number of snags, logs, and cover (Bull 2003b).

We calculated the percentage of source habitat within a watershed that had snag 

densities (>20 in d.b.h.) in the following classes (fig. 55):

• Low: <2.5/ac 

• Moderate: 2.6 to 8.9/ac 

• High: 9.0 to 39.3/ac

• Very high: >39.3/ac

These density classes were taken from DecAID, as described in the historical 

range of variability (HRV) methods sections to correspond to the different tolerance 

levels of the east-side mixed-conifer forest type (Mellen et al. 2006).

Road density— 

We included a road density variable to account for likely reduced snag densities 

along roads. Bate et al. (2007) found that snag numbers were lower adjacent to 

roads owing to removal for safety considerations, removal as firewood, and other 

management activities. Other literature has also indicated the potential for reduced 

snag abundance along roads (Wisdom et al. 2000). 

We calculated the percentage of source habitat in the following road density 

classes (fig. 55):

• Zero: <0.1 mi/mi2 open roads in watershed

• Low: 0.1 to 1.0 mi/mi2 open roads in a watershed

• Moderate: 1.1 to 2.0 mi/mi2 open roads in a watershed

• High: >2.0 mi/mi2 open roads in a watershed

Calculation of historical conditions—

• Habitat departure: Class 1

• Snag density: High

• Road density: Zero

The relative sensitivity of WI values to variables used in the pileated woodpecker model are shown in table 37.
168

GENERAL TECHNICAL REPORT PNW-GTR-907

Assessment Results

Watershed scores— 

The abundance of closed-canopied late-successional forests in the dry, mesic, 

and cold-moist forest types has declined from the historical condition. Currently, 

76 percent (n = 55) of the watersheds in the assessment area have less habitat than 

the historical median while the remainder of the watersheds (n = 17) showed little 

departure from the historical median (fig. 56). These conditions reflected the reduction in late-successional forests that have occurred in the assessment area and 

are consistent with the findings that Wisdom et al. (2000) reported for the North 

Cascades and Northern Glaciated Mountains ERUs.

Watersheds containing <740 ac of source habitat currently included the Ashnola, Lower Silkameen River, Upper Chewuch River, Lost River, and the Middle 

Yakima (fig. 56). The watersheds with the greatest amount of source habitat 

currently (>24,700 ac) are the Teanaway River, Upper Yakima River, West Fork 

Sanpoil, White-Little Wenatchee, Little Naches River, Wenatchee River, Stehekin, 

Chiwawa, and Ross Lake (fig. 56), about 39,500 ac. Historically, the Lower Pend 

Oreille watershed had the highest estimated amount of source habitat, 74,100 ac, yet 

we modeled less than 9,900 ac currently.

The availability of snag habitat was an important habitat feature within source 

habitat for pileated woodpeckers (Bull et al. 1986, 1992; Raphael and White 1984). 

We assessed the density of large-diameter snags (>20 in d.b.h.) within source habitat for each watershed. In 53 watersheds, >50 percent of the current source habitat 

had snag densities of <2.5 snags/acre (low category). Six watersheds (Icicle River, 

Pasayten River, White-Little Wenatchee River, Little Naches River, American 

River, and Bumping River) had >50 percent of the current source habitat with snag 

densities in the high category (9 to 39 snags/acre). 

Road densities were calculated to assess the effects roads have on snag densities. Road densities were variable. Ten watersheds had >50 percent of the source 

habitat in a road density of high while source habitat in 15 watersheds had snag 

densities primarily in the “zero” category. 

Table 37—Relative sensitivity 

of watershed index values 

to variables in the model for 

pileated woodpeckers

Variable Sensitivity rank

Habitat departure 1

Snag density 2

Road density 3
169

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Figure 56—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for pileated woodpeckers by watershed in the northeast Washington assessment area.
170

GENERAL TECHNICAL REPORT PNW-GTR-907

Because of the overall reduction in amount of source habitat, and lower snag 

densities when compared to historical conditions, the WI variables are generally 

low for this species (fig. 56). Seventy-five percent (n = 54) of the watersheds had a 

current WI value of low (<1). Eighteen percent (n = 13) had a WI value of moderate 

(>1 and <2), while 7 percent (n = 5) had high WIs (>2.0). We estimated the WI was 

historically about 2.6.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability 

for pileated woodpeckers within the assessment area is 45 percent of the historical 

capability. Dispersal across the assessment area was not considered an issue for 

this species because of their relatively high mobility. All five ecoregions currently 

contained at least one watershed with >40 percent of the median amount of historical source habitat. Thirty watersheds had >40 percent of the median amount of 

historical source habitat (42 percent). The current viability outcome is a 21-percent 

probability of an outcome B, 71 percent probability of a C outcome, indicating that 

habitat is likely patchily distributed or isolated and in low abundance (fig. 57). 

We estimated that 89 percent (n = 64) of the watersheds contained greater 

than 40 percent of the median amount of habitat historically and were distributed 

throughout all five ecoregions. The viability outcome historically was primarily an 

A outcome indicating habitat was broadly distributed and highly abundant (fig. 57). 

In summary, under historical conditions, pileated woodpeckers were likely 

well distributed throughout the assessment area; currently they are likely not as 

well distributed, and source habitat is less abundant. Likely, other species in the 

medium-large trees/cool/moist forests group have experienced similar declines in 

suitable environments.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Decline in the availability of late-successional source habitats, including 

large-diameter trees.

2. Loss of large snags in some of the source habitat and in areas that could be 

managed to provide future source habitat.

3. The future sustainability of dense dry forests with larger trees that have 

high fuel loads (Hessburg et al. 1999, 2007; Townsley et al. 2004).
171

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Sage Thrasher

Introduction

Sage thrashers were selected as a surrogate species to represent species of conservation concern associated with the shrub-steppe group in the woodland/grass/shrub 

family. This species represents the full range of habitats and risks associated with 

that group, including loss, fragmentation, and degradation of sagebrush (Artemisia

spp.) habitats. Sage thrashers were distributed throughout the central portion of 

the assessment area (Smith et al. 1997). Sage thrashers are easily surveyed using 

standard point count protocols. Sage thrashers were breeding-season residents of 

the assessment area (Reynolds et al. 1999); this assessment was for nesting habitat.

Model Description

Source habitat— 

Probability of occurrence of sage thrashers in shrub-steppe habitats was most

directly related to sagebrush cover, total shrub cover, shrub patch size, decreased

disturbance, and similarity of habitat within a 0.62-mi radius (Knick and Rotenberry 

1995). Sage thrashers were almost entirely dependent on sagebrush

habitats during the breeding season (Braun et al. 1976, Dobler et al. 1996, Knick and 

Rotenberry 1995, McAdoo et al. 1989, Reinkensmeyer et al. 2007). An abundance

 of breeding individuals has been positively correlated with sagebrush cover and 

negatively correlated with the cover of annual grasses (Kerley and Anderson 1995, 

Figure 57—Current and historical viability outcomes for the pileated woodpecker in the northeastern 

Washington assessment area.
172

GENERAL TECHNICAL REPORT PNW-GTR-907

Reynolds et al. 1999, Wiens and Rotenberry 1981). The primary limiting factor for 

sage thrashers was the loss, alteration, or degradation of sagebrush habitats (Braun et 

al. 1976, Cannings 2000, Weber 1980). Where complete replacement of native sagebrush habitat with crested wheatgrass (Agropyron cristatum) occurred, this species 

was eliminated (Reynolds and Trost 1980, 1981). Even removal of only large sagebrush in breeding habitats can limit use by thrashers (Castrale 1982). Sage thrashers 

were least abundant on sagebrush sites in poor condition, suggesting that they were 

more productive in less disturbed communities (Vander Hagen et al. 2000).

The spread of cheatgrass (Bromus tectorum) has had a negative effect on sage 

thrasher populations through its influence on fire regimes in western grasslands 

(Knick and Rotenberry 1997). Fires pose a threat to sage thrashers in terms of 

habitat loss as sagebrush does not resprout after burning (Castrale 1982). Kerley 

and Anderson (1995) found that sage thrashers were not present on burned areas 

9 years after a fire, and areas treated with herbicide had low sage thrasher populations 22 years after treatment. Although Petersen and Best (1987, 1999) found that 

sage thrasher abundance was unaffected by prescribed burning, which resulted 

in a mosaic of burned and unburned areas in southeastern Idaho, Welch (2002), 

McIntyre (2002), and Holmes (2007) reported that sage thrasher presence was 

reduced or did not occur on burned sagebrush sites.

For this analysis, source habitat for sage thrashers was considered to be the 

shrub-steppe vegetation zone (fig. 58). All potential habitat that burned since 1998 

was removed from consideration as source habitat in the model.

• Vegetation zone: Shrub-steppe

• Cover type: Shrub-steppe

Habitat effectiveness— 

Density of sagebrush obligate birds (including sage thrashers) was reported to 

decrease 39 to 60 percent within a 330-ft buffer of roads with low traffic volumes 

(Ingelfinger and Anderson 2004). As a result, we assumed that roads have a negative effect on the effectiveness of source habitat for sage thrashers. We assessed the 

potential for human disturbance to affect source habitat of sage thrashers with an 

adaptation of the habitat disturbance index described in Gaines et al. (2003). We 

buffered open roads by 330 ft on each side and then intersected this with our map of 
173

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

source habitat. We then used the following categories to estimate the potential 

effects of human disturbance on sage thrashers for each watershed (fig. 58):

• Low: >75 percent of the source habitat outside road and trail buffer within a 

watershed

• Moderate: 50 to 75 percent of the source habitat outside road and trail buffer within a watershed

• High: <50 percent of the source habitat outside road and trail buffer within 

a watershed

Patch size— 

Knick and Rotenberry (1995, 2002) reported that sage thrashers were highly sensitive to fragmentation of shrublands in southeast Idaho. Also, Vander Haegen et 

al. (2002) found higher predation rates on nests of sage thrashers in small patches 

of sagebrush (median 360 ac) compared to large patches (median 285,100 ac). 

Although Vander Haegen et al. (2000) reported that sage thrashers were not arealimited in eastern Washington state and were often found nesting in small habitat 

patches (<25 ac), subsequent analyses indicated that birds nesting in small patches 

experienced reduced nest success when compared to birds nesting in large habitat 

patches (Vander Haegen 2007). This lower reproductive success was manifested in 

Figure 58—Surrogate species assessment model for sage thrashers.
174

GENERAL TECHNICAL REPORT PNW-GTR-907

lower rates of nest survival, largely as a result of increased predation on nests. Thus, 

small patches of sagebrush were reproductive sinks for this species. The following 

classes were used to describe the effect of patch size on habitat quality (fig. 58):

• Small: 0 to <1,240 ac mean patch size of sagebrush habitat within a 

watershed

• Moderate: 1,240 to 2,470 ac mean patch size of sagebrush habitat within a 

watershed

• Large: >2,470 ac mean patch size of sagebrush habitat within a watershed

Variables considered but not included—

Grazing—Heavy grazing pressure has been reported to affect sage thrasher populations negatively (Bradford et al. 1998, Kerley and Anderson 1995), but they may 

be less sensitive to intensive grazing than other birds associated with shrub-steppe 

habitats (Kantrud and Kologiski 1982, Reynolds and Trost 1981). Saab et al. (1995) 

further reviewed several studies where heavy grazing resulted in a positive response in sage thrasher abundance. Because of the equivocal nature of the reported 

effects of grazing on sage thrashers, this variable was not included in the model.

Calculation of historical conditions—

• Departure of source habitat from HRV: 0.5

• Roads: Class low

• Patch size: Class large

The relative sensitivity of WI values to the variables used in the model for sage 

thrasher are shown in table 38.

Assessment Results

Watershed scores— 

Historically, 67 of 72 watersheds within the assessment area provided habitat for 

sage thrashers (i.e., >50 ac of habitat within the watershed). This analysis indicated 

Table 38—Relative sensitivity 

of watershed index values to 

variables in the model for sage 

thrashers

Variable Sensitivity rank

Habitat departure 1

Patch size 2

Road density 3
175

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

that 31 percent (n = 22) of watersheds within the assessment area currently provided 

habitat for sage thrashers. Watersheds with the greatest amounts of habitat were 

concentrated in the central portion of the assessment areas, including Columbia 

River-Lynch Coulee, Okanogan River-Omak Creek, and Upper ColumbiaSwamp Creek (fig. 59). However, within Okanogan River-Omak Creek and Upper 

Columbia-Swamp Creek <25 percent of the source habitat was managed by federal agencies. The watersheds with the least amount of source habitat were located 

across the eastern and western portions of the assessment area. All watersheds with 

habitat had low WI scores (>0.0 but <1.0) (fig. 59). A major factor that influenced 

the WI scores was the amount of source habitat compared to levels historically 

available in the watersheds (fig. 59).

Road density also affected suitability of watersheds as habitat for sage thrashers (Ingelfinger and Anderson 2004). However, road density in source habitat was 

generally low across the assessment area.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability for 

sage thrashers within the assessment area is 32 percent of the historical capability. 

Dispersal across the assessment area was not considered an issue for these species 

owing to their relatively high mobility. Four of five ecoregions contained at least 

one watershed with >40 percent of the median amount of historical source habitat 

(median was calculated across all watersheds with source habitat). Eighteen percent (n = 13) of the watersheds had >40 percent of the median amount of historical 

source habitat. Under those circumstances, there is a 50 percent probability that the 

current viability outcome for sage thrashers is D and a 40 percent probability that 

the current viability outcome for these species is E, indicating a patchy to isolated 

distribution and low abundance of source habitat (fig. 60). Other species associated 

with the shrub-steppe group in the woodland/grass/shrub family likely have similar 

outcomes.

Historically, dispersal across the assessment area was not considered an issue 

for this species. Four of five ecoregions contained at least one watershed with >40 

percent of the median amount of historical source habitat (median was calculated 

across all watersheds with source habitat). Fifty-eight percent (n = 42) of the 

watersheds had >40 percent of the median amount of historical source habitat. 

Under those circumstances, there was a 66.5 percent probability that the historical 

viability outcome for sage thrashers was A and a 21.5 percent probability that the 

historical viability outcome for these species was B, indicating habitat was broadly 

distributed and highly abundant (fig. 60).
176

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 59—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and 

(D) habitat condition class for sage thrashers (SATH) by watershed in the northeast Washington assessment area 

(NEWA).
177

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

In summary, under historical conditions, sage thrashers and other species 

associated with the shrub-steppe group in the woodland/grass/shrub family were 

likely well distributed throughout the assessment area; currently, they are not well 

distributed, have limited opportunity for interactions among populations, and are 

likely to be extirpated.

Our results for this species were similar to those reported in the broad-scale 

habitat analysis by Wisdom et al. (2000) in the ICBEMP. According to the ICBEMP 

terrestrial vertebrate habitat analyses, historical source habitats for sage thrashers included portions of the northern Cascade Range and the Northern Glaciated 

Mountains ERUs that overlap our assessment area (Wisdom et al. 2000). Within 

this historical habitat, declines in source habitats have been extensive—71 percent 

in the Northern Cascades and -84 percent in the Northern Glaciated Mountains 

according to Wisdom et al. (2000).

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Reduction and fragmentation of suitable shrub-steppe source habitats from 

historical levels.

2. Negative effects of roads and motorized trails within source habitats.

Figure 60—Current and historical viability outcomes for sage thrashers in the northeast Washington 

assessment area.
178

GENERAL TECHNICAL REPORT PNW-GTR-907

Tailed Frog 

Introduction

The tailed frog was selected as a surrogate species to represent the conifer riparian 

group, specifically habitats associated with moderate-elevation streams. Only one 

other species, the black swift, occurs in this group, and the swift is associated with 

steep cliffs near waterfalls. Locations of the black swift in the assessment area are 

few. Tailed frogs occur in mountainous streams on the west and east side of the 

Cascade Range and in the Coast Ranges of western Oregon and Washington (Leonard et al. 1993). In addition, they have a disjunct distribution that includes the Blue 

Mountains (Leonard et al. 1993). Tailed frog distribution within the assessment area 

is limited to the east side of the north Cascade Range, and they do not occur on the 

portion of the Okanogan-Wenatchee National Forest east of the Okanogan River or 

on the Colville National Forest (Dvornich et al. 1997a). 

Model Description

Source habitat— 

Tailed frogs reside in and next to perennial mountain streams (Dupuis et al. 2000). 

Mating, egg-laying, and larval development occur in streams. Adult female frogs 

deposit egg masses beneath large relatively stable cobbles or boulders in the summer, and hatchlings emerge the following spring. At northern latitudes, it takes up 

to four additional summers for tadpoles to metamorphose and begin a life of both 

lotic and terrestrial activity (Brown 1990, Daugherty and Sheldon 1982). Thus, the 

larval life stages are particularly vulnerable to land uses that alter channel conditions (Aubry 2000, Bull and Carter 1996, Bury 1983, Corn and Bury 1989, Dupuis 

and Steventon 1999, Welsh and Ollivier 1998).

Amphibian populations, and specifically tailed frogs, are believed to be at risk 

from the effects of timber harvesting in both upland and riparian zones (Aubry 

2000, Bull and Carter 1996, Bury and Corn 1988, Bury 1994, Dupuis 1997). 

Considerable efforts have been made to understand these effects on the west-side 

forests of Oregon, Washington, and British Columbia (Aubry 2000, Biek et al. 

2002, Dupuis and Steventon 1999, Stoddard and Hayes 2005, Vesely and McComb 

2002). These studies have reported differences in amphibian community composition depending on stand age (Aubry 2000) and width of riparian buffers (Veseley 

and McComb 2002), positive associations with the presence of amphibians and 

old forests adjacent to streams (Stoddard and Hayes 2005), and amphibian population declines following clearcut harvest (Dupuis and Steventon 1999). In the drier 
179

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

interior forests east of the Cascade Crest in Washington, Piper (1996) conducted 

monitoring of tailed frogs on the Wenatchee National Forest in areas with and without regeneration timber harvest adjacent to the streams. She found that the number 

of tailed frog captures were considerably less where timber harvest had occurred. 

However, since the implementation of the Northwest Forest Plan, watersheds, 

including those that provide tailed frog source habitats, have received considerable 

protection from the negative effects associated with timber harvest and road building, improving conditions for riparian-associated species (Gallo et al. 2005).

Owing to our limited ability to map riparian habitats, we assumed that the 

amount of habitat currently available was about the same as the amount of habitat 

that was historically available. Therefore, our assessment for the tailed frog focused 

on factors that influenced habitat quality and not factors that may have caused 

habitat loss. We modeled source habitat for tailed frogs using a combination of 

stream order, cover type, and tree structure. Our model included the following GIS 

layers (fig. 61).

Figure 61—Surrogate species assessment model for the tailed frog.
180

GENERAL TECHNICAL REPORT PNW-GTR-907

Forest cover types: Douglas-fir, grand fir, western hemlock, Pacific silver fir, 

Engelmann spruce, western redcedar, mountain hemlock, subalpine fir, riparian 

deciduous

Tree structure and size: Single/multistory, >38 cm d.b.h. QMD

Canopy closure: >50 percent

Stream orders: 3 to 5 with 328-ft buffer on each side

Grazing— 

We found no studies on the effects of grazing on tailed frogs; several studies have 

shown that livestock grazing can change the composition and quality of riparian 

habitats, cause soil compaction, and streambank trampling (see Krausman 1996 

and Wales 2001 for reviews). Of particular importance is the potential for grazing 

to contribute sedimentation to a stream providing tailed frog habitat (Waters 1995, 

Welsh and Ollivier 1998). Thus, we accounted for the potential effects of grazing on 

tailed frogs by mapping cattle grazing allotments (with attributes to identify active 

allotments) and overlaying these onto maps of tailed frog source habitat (fig. 61).

We used the following categories to assess these potential impacts within each 

watershed: 

• Zero: No source habitat within an active cattle grazing allotment

• Low: <25 percent of the source habitat within an active cattle grazing 

allotment

• High: >25 percent of the source habitat within an active cattle grazing 

allotment

Habitat effectiveness— 

Roads can influence riparian habitats for amphibians by removing habitat, limiting 

the ability of amphibians to disperse across roads, creating a source of mortality, 

and as a source of fine sediment deposited in amphibian habitats (Demaynadier and 

Hunter 2000, Dupuis and Steventon 1999, Fahrig et al. 1995, Welsh and Ollivier 

1998, Yanes et al. 1995). Roads can contribute sediment to streams and reduce 

the densities of tailed frogs (Welsh and Ollivier 1998). In addition, where roads 

intersect with riparian habitats, removal of hazard trees for safety and snags for 

woodcutting can alter the structure of riparian habitats. This is most likely to occur within 200 ft on each side of a road (Hamman et al. 1999, Gaines et al. 2003, 

Wisdom and Bate 2008). We assessed the potential impacts of roads on tailed frogs 

using road density within source habitat as an indicator of the effects of roads on 

habitat effectiveness (fig. 61). To estimate road density, a moving-windows routine 
181

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

with a 0.9-km (0.6-mi) radius circular window was used. We used the riparian route 

density index (described in Gaines et al. 2003) to assess the amount of source habitat within different road density classes and assigned each watershed to a level of 

habitat effectiveness:

• Low habitat effectiveness: >25 percent of the source habitat with road densities >2 mi/mi2

• Moderate habitat effectiveness: >25 percent of the source habitat with road 

densities >1 mi/mi2

• High habitat effectiveness: <25 percent of the source habitat with road densities >1 mi/mi2

Invasive species— 

Studies have shown the negative effects of nonnative trout on amphibian communities (Dunham et al. 2004, Hecnar and M’Closkey 1997) and specifically on tailed 

frog occurrence (Feminella and Hawkins 1994). We used fish distribution data collected during stream surveys to determine if the presence of nonnative fish were 

likely present within source habitats in each watershed (fig. 61). 

Calculation of historical conditions—

• Source habitat: Depature class 1

• Grazing: Zero

• Habitat effectiveness: High

• Invasive species: Not present

The relative sensitivity of WI values to variables used in the model for tailed frog 

are shown in table 39.

Model evaluation— 

We compared mean WI values derived from 279 points where tailed frogs were 

known to occur to 146 random points. The mean WI values for the occurrence 

points (1.89) were significantly higher (t = 1.97, P = 0.0008) than the mean derived 

from the random points (1.71) indicating that our model was effective in identifying 

watersheds with suitable environments for tailed frogs.

Assessment Results

Watershed scores— 

Forty-eight watersheds on the Okanogan-Wenatchee National Forest were evaluated 

for tailed frogs; they are not known to occur on the Colville National Forest. Eleven 

of the watersheds (23 percent) had WI scores that were high (>2.0), 12 watersheds 
182

GENERAL TECHNICAL REPORT PNW-GTR-907

(25 percent) had moderate scores (1.0 to 2.0), and 26 watersheds (54 percent) had 

low scores (<1) (fig. 62). Watersheds that had some of the greatest abundance of 

habitat (>3,700 ac), and high WI scores were Ross Lake, Icicle Creek, and Stehekin 

(fig. 62). Other watersheds that had large amounts (>2,500 ac) of tailed frog source 

habitat, but moderate or low WI scores, included Sinlahekin Creek, Little Naches 

River, Peshastin Creek, White-Little Wenatchee, Cle Elum River, Chiwawa River, 

Teanaway River, Upper Yakima River, and Wenatchee River (fig. 62). 

Road densities in tailed frog source habitat were high, leading to overall low 

habitat effectiveness. Within 19 percent (n = 9) of the watersheds, there was a high 

level of habitat effectiveness for tailed frog source habitat, in 23 percent (n = 11) of 

the watersheds there was a moderate level of habitat effectiveness, and in 58 percent 

(n = 28) of the watersheds habitat effectiveness was low.

The assessment of the amount of source habitat for tailed frogs in active grazing 

allotments had mixed results. Our analysis showed that in 27 percent (n = 13) of the 

watersheds, cattle were not grazed in source habitat; in 35 percent (n = 17) of the 

watersheds, >0 to 25 percent of the source habitat was in an active cattle grazing 

allotment; and in 38 percent (n = 18) of the watersheds, >25 percent of the source 

habitat was in an active cattle grazing allotment.

Although 90 percent (n = 43) of the watersheds have nonnative trout present, 

the true impact of this on tailed frog populations is not known, and it is a risk factor 

that is in need of further investigation and monitoring. We calibrated the overall 

negative effect of this risk factor to be relatively small owing to uncertainty in the 

effects of this risk factor.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat distribution index. The WWI scores indicated that the current habitat capability for the 

tailed frog within the assessment area is 43 percent of the historical capability. 

Table 39—Relative sensitivity of 

watershed index values to variables 

in the model for tailed frogs

Model variables

Order of variable 

weighting

Source habitat 1

Grazing 2

Habitat effectiveness 4

Invasive species 3
183

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Figure 62—Current amount of (A) source (acres), (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for tailed frogs by watershed in the northeast Washington assessment area.
184

GENERAL TECHNICAL REPORT PNW-GTR-907

Currently and historically, 75 percent (n = 36) of the watersheds contain source 

habitats that were estimated to be above 40 percent of the historical median. The 

watersheds with >40 percent were distributed across all of the three ecoregions in 

which the tailed frog is distributed.

The current viability outcome for tailed frogs in the assessment area is a 73 percent probability of C and a 23 percent probability of B, which indicates that suitable 

environments are distributed frequently as patches or existed at low abundance (fig. 

63). Gaps in suitable environments are likely large enough such that some subpopulations are isolated, limiting opportunity for interspecific interactions. Historically, 

the viability outcome for tailed frogs was estimated to have a 76 percent probability 

of A, and a 16 percent probability of B with some gaps in suitable environments 

occurring naturally (fig. 63).

In summary, the abundance and distribution of suitable environments for the 

tailed frog, and likely other species associated with the conifer riparian group, 

have been reduced. The viability of species associated with this habitat could be 

enhanced by habitat restoration.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Grazing has a negative influence on quality of tailed frog habitat in some 

watersheds. 

Figure 63—Current and historical viability outcomes for the tailed frogs in the northeast Washington 

assessment area.
185

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

2. Currently, roads are having widespread impacts on tailed frog source 

habitats in a high proportion of watersheds. 

3. Vegetation management within source habitat may reduce habitat availability, increase sedimentation, and affect stream temperatures.

Tiger Salamander

Introduction

The tiger salamander was selected as a surrogate species for the grass/shrub group 

owing to their specific association with wetland and ponds that occur within dry 

forest and shrub-steppe habitats not represented by other surrogate species in the 

family or group. In Washington, the tiger salamander occurs in portions of the 

Columbia Basin and northeastern Washington, and they range in elevation from 

670 to 3,000 ft (Leonard et al. 1993, Nussbaum et al. 1983). Habitat occurs on the 

Colville and Okanogan-Wenatchee National Forests with the exception of Kittitas 

and Yakima Counties; the Columbia River is considered a barrier to their expansion 

into these counties (Dvornich et al. 1997). 

Model Description

Source habitat— 

Tiger salamanders use a variety of seasonal and permanent water bodies, including 

lakes, reservoirs, and farm ponds (Leonard et al. 1993). Previous efforts to model tiger 

salamander habitats used open water and wetlands that occurred within shrub-steppe 

and open dry forests (Dvornich et al. 1997). Important features of breeding sites 

include persistence of water until larval development is complete (from mid-March 

to mid-August), shallow (generally <3 ft) water depths along at least portions of the 

water body, soft bottom substrate, abundant emergent vegetation, suitable cover for 

metamorphs (amphibians that have recently transformed to the adult stage) along the 

shoreline, and absence of introduced fish (COSEWIC 2001, Sarell 2004). Outside the 

breeding period, terrestrial tiger salamanders use grassland, shrub-steppe, and open 

forest habitats (COSEWIC 2001). Important habitat features include friable soils that 

permit burrowing, rodent burrows for shelter, and availability of food (COSEWIC 

2001, Sarell 2004, Semlitsch 1998).

For this assessment, to identify source habitat for the tiger salamander, we used 

the National Wetlands Inventory and the cover type GIS data layers (fig. 64).

• National Wetlands Inventory: All lacustrine and palustrine wetlands

• Cover types/vegetation zones: Shrub-steppe, ponderosa pine

Currently, roads are 

having widespread 

impacts on tailed frog 

source habitats in a 

high proportion of 

watersheds.
186

GENERAL TECHNICAL REPORT PNW-GTR-907

Grazing— 

While studies were not found on the effects of grazing on tiger salamanders, several 

studies have shown that livestock grazing can change the composition and quality 

of riparian habitats, cause soil compaction, streambank trampling, and increased 

nutrient input to water (see Krausman 1996, Sarell 2004 , Wales 2001 for reviews). 

Leege et al. (1981) found litter to be an important habitat component for many small 

mammals, reptiles, and amphibians, with litter biomass twice as high in livestock exclosures as compared to grazed areas. Heavy livestock use near the ponds 

can cause the collapse of small mammal burrow entrances needed for aestivation 

(Harvey et al. 2000). Thus, we accounted for the potential effects of grazing on 

tiger salamanders by mapping grazing allotments (with attributes to identify active 

allotments) and overlaying these onto maps of source habitats. We then categorized 

Figure 64—Surrogate species assessment model for the tiger salamander.
187

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

the amount of source habitat in an active grazing allotment using 10 percent increments from 0 to 100 percent, with increasing poorer habitat outcomes as the proportion of source habitat in an active allotment increased (fig. 64).

Invasive animals— 

Several studies have documented the negative effects of nonnative fishes on amphibians (see Dunham et al. 2004 for a review), and some studies have specifically 

addressed effects to tiger salamanders (Collins et al. 1988, Corn et al. 1997, Fisher 

and Shaffer 1996). The effects that nonnative fishes had on amphibians include 

direct mortality from predation, competition for food resources, and displacement 

from important habitats (Dunham et al. 2004, Fisher and Shaffer 1996, Hecnar and 

M’Closkey 1997).

To assess the potential impacts of nonnative fishes and fish stocking, we 

reviewed the fish stocking records (available from Washington Department of Fish 

and Wildlife and digitized by U.S. Forest Service) for areas that comprised source 

habitat for tiger salamanders. We then categorized the amount of source habitat that 

received fish stocking for each 5th-field watershed as follows (fig. 64):

• Low: <25 percent of the source habitats had fish stocking

• Moderate: 25 to 50 percent of the source habitats had fish stocking

• High: >50 percent of the source habitats had fish stocking

Habitat effectiveness— 

Studies of the effects of roads on amphibians have documented road-related mortalities (Ashley and Robinson 1996), reduced permeability to amphibian movements 

as a result of edge effects (Gibbs 1998), and roads as partial barriers to movements 

(DeMaynadier and Hunter 2000, Marsh et al. 2005). To account for these potentially negative effects in our tiger salamander model, we compiled roads information 

from the national forests and Washington Department of Natural Resources. We 

used a moving windows analysis to estimate road density within source habitat for 

each watershed. We then used the following categories to assess habitat effectiveness (fig. 64):

• Low habitat effectiveness: >25 percent of the source habitat with road densities 

>2.0 mi/mi2

• Moderate habitat effectiveness: >25 percent of the source habitat with road 

densities >1.0 mi/mi2

• High habitat effectiveness: <25 percent of the source habitat with road densities >1.0 mi/mi2
188

GENERAL TECHNICAL REPORT PNW-GTR-907

Calculation of historical conditions—

• Source habitat: Habitat departure class -2

• Grazing: None

• Invasive animals: Low

• Habitat effectiveness: High

The relative sensitivity of WI values to the variables used in the model for tiger 

salamander are shown in table 40.

Assessment Results

Watershed scores— 

We evaluated 58 watersheds as having potential habitat for tiger salamanders in the 

assessment area. Seventy-four percent (n = 43) of the watersheds had WI scores 

that were high (>2.0) and they were widely distributed across the assessment area. 

In addition, 26 percent (n = 15) of the watersheds had moderate (1.0 to 2.0) WI 

scores (fig. 65). 

Watersheds that currently have the greatest amount of source habitat include 

the Lower Okanogan River, Okanogan River-Omak Creek, Upper Okanogan River, 

Middle Methow River, and Okanogan River-Bonaparte Creek (fig. 65). The median 

amount of source habitat across all of the watersheds with at least some source 

habitat was 754.4 ac.

Fish stocking was estimated to be at a moderate level in all of the watersheds. 

Twelve percent of the watersheds (n = 7) had >50 percent of the source habitat 

within an active grazing allotment, 7 percent (n = 4) had 25 to 50 percent of the 

source habitat in an active grazing allotment, and 81 percent (n = 47) had <25 

percent of the source habitat in an active grazing allotment. Most (71 percent, n = 

41) of the watersheds had a high level of habitat effectiveness, 26 percent (n = 15) 

had a moderate level of habitat effectiveness, and 3 percent (n = 2) had a low level.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier) and a habitat distribution index. The WWI portion of the viability outcome model showed that the 

current habitat capability is 48 percent of the historical habitat capability. This score 

is largely influenced by a reduction in the availability of source habitat from historical conditions. Thirty-five (48 percent) of the watersheds have source habitat that 

was >40 percent of the historical median. These watersheds are distributed across 

all of the ecoregions within the distribution of the tiger salamander.
189

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 40—Relative sensitivity of 

watershed index values to variables

in the model for tiger salamander

Model variables

Order of variable 

weighting

Source habitat 1

Grazing 2

Fish stocking 3

Habitat effectiveness 4

Figure 65—Current amount of (A) source habitat (acres), (B) watershed index, and (C) habitat condition class for tiger salamanders (TISA) by watershed in the northeast Washington assessment area.

A B

C
190

GENERAL TECHNICAL REPORT PNW-GTR-907

Historically, 50 percent of the watersheds had source habitat amounts >40 

percent of the historical median of all watersheds. The watersheds with >40 percent 

were distributed across all four of the ecoregions that occur within the range of the 

tiger salamander.

Currently, the viability outcome for the tiger salamander is estimated to be a 71 

percent probability of outcome C and a 21 percent probability of outcome B, which 

suggests that suitable environments are distributed frequently as patches or exist 

in low abundance (fig. 66). Species with this outcome are likely well distributed in 

only a portion of the assessment area. Historically, viability outcomes were a 66.5 

percent probability of outcome A and a 21.5 percent probability of B where suitable 

environments were more broadly distributed or of high abundance (fig. 66). In addition, the suitable environments were better connected, allowing for relatively more 

interspecific interactions. A reduction in the availability of suitable environments 

for the tiger salamander may have occurred in the assessment area compared to the 

historical distribution and condition of their habitats. However, only 12 watersheds 

have source habitat amounts in which >25 percent of habitat is located in federal 

ownership. This greatly limits the contribution that federal lands can make to the 

viability of this species.

Figure 66—Current and historical viability outcomes for the tiger salamander in the northeast Washington 

assessment area.
191

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Fish stocking can influence the survival of juvenile amphibians.

2. Grazing has reduced the quality of source habitat in some watersheds.

3. Roads can influence the survival of amphibians when roads occur in proximity to source habitats.

4. The amount of source habitat that is on federal lands is limited across the 

assessment area and limits the contribution that federal lands can make to 

the viability of this species.

Townsend’s Big-Eared Bat

Introduction

The Townsend’s big-eared bat was selected as a surrogate species to represent 

the unique habitat of the chambers and caves group (Marcot 1984, Nagorsen and 

Brigham 1993) along with other bat species. In addition, these bats use large trees 

and snags (Feller and Pierson 2002, Mazurek 2004). Townsend’s big-eared bats 

are moth specialists but also consume a variety of other arthropods when available 

(Nagorsen and Brigham 1993, Ross 1967, Whitaker et al. 1977). In Washington, 

Townsend’s bats are found in west-side lowland conifer-hardwood forest, ponderosa 

pine forest and woodlands, mixed highland conifer forest, east-side mixed-conifer 

forest, shrub-steppe, and both east- and west-side riparian wetlands (Johnson and 

Cassidy 1997, WDFW 2005). 

Though Townsend’s big-eared bats are relatively widespread across the assessment area, with at least one site occurring on or adjacent to each of the national 

forests, they are rare owing to their restrictive roosting requirements (Johnson and 

Cassidy 1997, Woodruff and Ferguson 2005). Because of the limited number of 

known locations for this species, we did not develop a surrogate species assessment 

model but rather provide a qualitative assessment of Townsend’s habitat relationships and general management considerations.

In Washington, old buildings, silos, concrete bunkers, barns, caves, and mines 

are common roost structures (WDFW 2005). In northwestern California, both 

individuals and nursery colonies have been located in very large trees (Feller and 

Pierson 2002, Heady and Frick 2001, Mazurek 2004).
192

GENERAL TECHNICAL REPORT PNW-GTR-907

Risk factors— 

The risk factors that were identified for this species include loss of roost sites because of cave and mine closures and destruction of abandoned buildings, disturbance of roosting bats from human activities, mortality of roosting bats or total loss 

of colonies because of vandalism and shooting, and reduction in prey base (moths) 

through use of insecticides.

The loss of roosts is a large concern because new mines are not being created 

at the rate they are being lost, and abandoned buildings are becoming much less 

common (Woodruff and Ferguson 2005). In addition, loss of large hollow trees that 

might serve as valuable roosts may occur during either wild or prescribed fire.

Because insecticides reduce insects that are a potential source of prey, insecticide use near hibernacula and nursery roosts may limit populations, especially if 

the bats leaving the hibernacula are nursing (Humphrey and Kunz 1976, Sample 

1991, Wackenhut 1990).

Disturbance of roost by humans (e.g., recreation, mining, bat research, vandalism) is noted as a concern by many researchers (Ellison et al. 2005, Pierson and 

Rainey 1998, Woodruff and Ferguson 2005).

Management Considerations

The following issues were identified during this assessment from published literature for consideration by managers:

1. Caves and mines may provide summer or winter roosting habitat or both.

2. Big-eared bats may be sensitive to human disturbance during critical 

periods (for hibernacula 15 May to 15 September, for nursery sites 15 

September to 1 April). It is especially important to consider the potential for 

the spread of white-nosed syndrome that is facilitated by human visitation.

3. Application of pesticides near bat roosts may cause disturbance and reduce 

prey populations.

4. Research and monitoring may cause disturbance of roosts.

5. Large trees and snags are key habitats for bats that are known to be below 

historical levels (Hann et al. 1997, Harrod et al. 1999, Hessburg et al. 1999a).

6. Buildings may be used by Townsend’s bats as roosting habitat. 

Various Bat Species 

Introduction

We identified 11 species of bats as species of conservation concern. We placed these 

species among four of the family groups described in chapter 1. They were placed 
193

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

in the medium to large tree forests, open forests, woodland/grass/shrub, and chambers/caves groups (see table 41). The general habitats of these species are described 

by the Western Bat Working Group; their known roosting sites, and a list of desired 

conservation actions by species are identified in the Oregon Conservation Strategy 

(ODFW 2005). The fringed myotis, pallid bat, and Townsend’s big-eared bat were 

chosen as surrogate species for their particular groups, largely owing to their high 

dependence on unique and not necessarily widespread roosting sites.

However, we did not develop WI models for any of these species. We felt we 

did not have the knowledge to adequately map habitat and develop a model at this 

scale for these species. We have described habitat variables researchers have found 

important for all bats in general. 

Source habitat— 

Bats use resources at the landscape scale. Land management considers the juxtaposition of all habitat components: roosting, foraging areas, and water resources. It is 

suspected that the closer the essential components are to each other (e.g., less than 

several miles: Keinath 2004 fringed myotis assessment), the higher the likelihood of 

persistence. Hayes and Loeb (2007) added clutter vegetation that has the potential 

to impede bat echolocation and flight to this list of habitat attributes that play a critical role in defining niches for bats.

Roost sites— 

Suitable characteristics of roost sites differ among species and sex (Broders and 

Forbes 2004), and optimal thermal conditions at roost likely differ with species, 

reproductive status, weather, age, and time of year (Hayes and Loeb 2007). A recent 

meta-analysis of tree roost selection of North American forest bats showed that 

roost trees of bats were tall with large d.b.h. and in stands with open canopy and 

high snag density (Kalcounis-Ruppell et al. 2005). However, Hayes (2003) suggested that an overreliance on one habitat type or topographic setting for retaining roost 

habitat is unlikely to provide the conditions necessary to meet the habitat needs for 

bats across seasons. For example, thermal characteristics of riparian areas often 

differ from upslope forests so the exclusive retention of snags and wildlife trees in 

riparian areas is not likely to be in the best interest of bat conservation.

In addition, the ephemeral nature of snag roosts and the movement by colonies 

of bats among several snags within seasons indicate that tree-roosting bats require 

areas of high snag density, perhaps more so than cavity-nesting birds (Baker and 

Lacki 2006, Rabe et al. 1998). Baker and Lacki (2006) suggested forest management practices target and set aside large-diameter (e.g., >24 in d.b.h.) snags surrounded by snag densities of >100/ac in snag management efforts directed toward 
194

GENERAL TECHNICAL REPORT PNW-GTR-907 Table 41—Summary of the conservation status, habitat relations, and conservation actions for various bat species within the northeastern Washington assessment area (continued) Family Species Focala Statusb Western Bat Working Group general- ized habitat description Roosting sites Potential conservation actions (from Oregon Conservation Strategy) Medium- to large- tree forests Hoary bat (Lasiurus cinereus) I Solitary and roosts primarily in foliage of both coniferous and deciduous trees, near the ends of branches, 3 to 12 m 

above the ground. Roosts are usually at the edge of a clearing. Some unusual roosting situations have been reported in caves, beneath a rock ledge, in a woodpecker hole, in a grey squirrel nest, under a driftwood plank, and clinging to the side of a building.

Trees, rocks Investigate data gaps and use results to 

guide management actions.

Medium- to largetree forests Silver-haired bat (Lasionycteris 

noctivagans)

I Maternity roosts appear to be almost 

exclusively in trees—inside natural hollows and bird-excavated cavities or under loose bark of large-diameter snags. Roosting sites are generally at least 15 m above the ground. Males and females change roosts frequently, and use multiple roosts within a limited area throughout the summer, indicating that clusters of large trees are necessary.

Trees Maintain late-successional conifer 

habitats; maintain and create largediameter hollow trees, and largediameter, tall, and newly dead snags during forest management activities.

Medium- to largetree forests Long-legged myotis (Myotis volans) I A bat primarily of coniferous forests. Also occurs seasonally in riparian and desert 

habitats. Uses abandoned buildings, cliff crevices, exfoliating tree bark, and hollows within snags as summer day roosts; caves and mine tunnels as hibernacula.

Trees, 

snags, rocks, cliffs, caves, mines

Maintain and create large-diameter 

hollow trees and large-diameter tall, newly dead snags in riparian and upland habitat; maintain and restore diverse riparian areas; complete bridge replacement and maintenance when bats are absent.
195

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 41—Summary of the conservation status, habitat relations, and conservation actions for various bat species within the northeastern Washington assessment area (continued)Family Species Focala Statusb

Western Bat Working Group generalized habitat description

Roosting sites

Potential conservation actions (from Oregon Conservation Strategy)

Open forest California myotis 

(Myotis californicus)

I While typical of deserts and interior 

basins in the Western United States, M. californicus also occurs in forested and montane regions. During summer, roost alone or in small groups in caves, mines, rocky hillsides, under tree bark, and in buildings. Recent studies in Canada have documented maternity colonies of up to 52 individuals roosting under sloughing bark, and in cracks and hollows of large-diameter, intermediate-stage snags (preferably ponderosa pine).

Trees, 

caves, mines, buildings

Maintain and create large snags during 

forest management activities; complete bridge replacement and maintenance when bats are absent.

Open forest Fringed myotis 

(Myotis thysanodes)

F I Appears to be most common in drier 

woodlands (oak, ponderosa pine) but is found in a wide variety of habitats including desert scrub, mesic coniferous forest, grassland, and sage-grass steppe. Roosts in crevices in buildings, underground mines, rocks, cliff faces, and bridges. Roosting in decadent trees and snags, particularly large ones, is common throughout its range in the Western United States and Canada. 

Trees, 

snags, cliffs, rocks, mines, buildings

Use gates and seasonal closures to protect known hibernacula; maintain and 

create large-diameter hollow trees and large-diameter tall, newly dead snags during forest management activities.

Open forest Long-eared myotis 

(Myotis evotis)

I Occurs in semiarid shrublands, sage, 

chaparral, and agricultural areas, but is usually associated with coniferous forests. Individuals roost under exfoliating tree bark, and in hollow trees, caves, mines, cliff crevices, sinkholes, and rocky outcrops on the ground.

Trees, 

snags, cliffs, rocks, mines, buildings
196

GENERAL TECHNICAL REPORT PNW-GTR-907 Table 41—Summary of the conservation status, habitat relations, and conservation actions for various bat species within the northeastern Washington assessment area (continued) Family Species Focala Statusb Western Bat Working Group general- ized habitat description Roosting sites Potential conservation actions (from Oregon Conservation Strategy)

Woodland/ 

grass/shrub

Western small-footed 

myotis (Myotis ciliolabrum)

I Occurs in deserts, chaparral, riparian 

zones, and western coniferous forest; it is most common above piñon-juniper forest. Individuals are known to roost singly or in small groups in cliff and rock crevices, buildings, concrete overpasses, caves, and mines

Trees, cliffs, 

rocks, caves, mines, buildings

Woodland/ 

grass/shrub

Yuma myotis (Myotis 

yumanensis)

I Occurs in a variety of habitats including 

riparian, arid scrublands and deserts, and forests. Roosts in bridges, buildings, cliff crevices, caves, mines, and trees. Individuals become active and forage just after sunset, feeding primarily on aquatic emergent insects.

Trees, cliffs, 

rocks, caves, mines, buildings

Woodland/ 

grass/shrub

Spotted bat (Euderma 

maculatum)

I Has been found in vegetation types that 

range from desert to subalpine meadows, including desert-scrub, pinyon-juniper woodland, ponderosa pine, mixed-conifer forest, canyon bottoms, rims of cliffs, riparian areas, fields, and open pasture. During summer, bats may travel from roosts in desert-scrub to forage in highelevation meadows, returning to roosts within an hour of dawn.

Cliffs, caves Maintain open water sources in desert 

landscapes. Manage rock features such as cliffs to avoid conflict with recreational use and rock removal. Maintain and restore native shrubsteppe habitat.
197

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 41—Summary of the conservation status, habitat relations, and conservation actions for various bat species within the northeastern Washington assessment area (continued)Family Species Focala Statusb

Western Bat Working Group generalized habitat description Roosting sites Potential conservation actions (from Oregon Conservation Strategy)

Woodland/ 

grass/shrub

Pallid bat (Antrozous 

pallidus)

F I Day and night roosts include crevices in 

rocky outcrops and cliffs, caves, mines, tree boles, cavities in oaks, exfoliating ponderosa pine and valley oak bark, deciduous trees in riparian areas, and fruit trees in orchards), and various human structures such as bridges (especially wooden and concrete girder designs), barns, porches, bat boxes, and humanoccupied as well as vacant buildings. They forage over open shrub-steppe grasslands, oak savannah grasslands, open ponderosa pine forests, talus slopes, gravel roads, lava flows, fruit orchards, and vineyards.

Trees, cliffs, 

rocks, caves, mines, buildings

Use gates and seasonal closures to protect known roost sites during sensitive 

times (raising young and hibernation). Maintain open water sources in dry landscapes. Manage rock features such as cliffs to avoid conflict with recreational use and rock removal. Complete bridge replacement and maintenance when bats are absent. Maintain large pine snags in shrubsteppe/forest ecotones. Maintain and restore native grassland, shrub-steppe and open ponderosa pine habitats.

Chambers/ 

caves

Townsend’s big-eared 

bat (Corynorhinus townsendii)

F C Reported in a wide variety of habitat 

types ranging from sea level to 2.1 mi. Habitat associations include coniferous forests, mixed meso-phytic forests, deserts, native prairies, riparian communities, active agricultural areas, and coastal habitat types. Distribution is strongly correlated with the availability of caves and cavelike roosting habitat, including abandoned mines. Foraging associations include edge habitats along streams, adjacent to and within a variety of wooded habitats.

Caves Use gates and seasonal closures to protect known roost sites during sensitive 

times (raising young and hibernation). Maintain buildings used as roosts. Maintain and create large-diameter hollow trees during forest management activities. Monitor roosts. 

a = F = Surrogate species, b = I = species of conservation concern.; C = USFWS canadiates species
198

GENERAL TECHNICAL REPORT PNW-GTR-907

conservation of bat-roosting habitat. A study in northern California on Myotis 

thysanoides found that regular pockets containing over 200 large (>24 in d.b.h.) 

snags/ac may be necessary to support populations of this species (Weller and Zabel 

2001). Also, because of the short time that bark remains on snags (sloughing bark is 

used for roosting by bats), bats require higher early decay snag densities than birds 

(Ellison et al. 2005, Rabe et al. 1998).

Maintaining roost trees and replacements across the landscape in a variety of 

topographic settings is a logical and conservative approach that should provide the 

broad spectrum of conditions necessary to meet the varying needs of bats. 

Efforts to restore ponderosa pine forest with reintroduction of fire could result 

in the loss of large-diameter trees, dead tops, and snags (Rancourt et al. 2008). 

Management strategies should be implemented to protect these large defective trees 

and snags during forest restoration. Selective thinning of areas with dense ponderosa pine surrounding potential roost trees and removal of excess duff and debris 

around the base of the tree(s), dead-top or snag prior to burning may help protect 

these potential roost sites.

Recreational rock climbing is increasing in popularity in Washington. The 

cracks and crevices in rock faces that provide attractive sites for climbers also 

provide sites for bat roosting. High climbing activity may displace roosting bats and 

increase threats to species of concern.

Limited research suggests that vegetative structure and habitat that surrounds 

caves may have an influence on use of caves as roosts by some species or in some 

situations, but not on others (Raesly and Gates 1987, Wethington et al. 1997). 

Foraging— 

When foraging, bats often move along forest edges more than within the forest 

interior (Black 1974, Crampton and Barclay 1996, de Jong 1994, Kunz and Martin 

1982). This may facilitate orientation but may also maximize contact with insect 

prey. When comparing bat foraging activity among forests, clearcuts, and water 

bodies, activity was found to be higher around water bodies (Lunde and Harestad 

1986). Other researchers have also found that foraging areas usually encompassed 

a body of open water or riparian corridor (Grindal et al. 1999, Waldien and Hayes 

2001). Forested corridors connecting forested patches have been shown to provide 

valuable foraging habitat as well as travel corridors for bats between roosting and 

foraging sites (van Zyll de Jong 1995).

Bat activity has been found to be higher in thinned stands than in unthinned 

stands (Humes et al 1999, Loeb and Waldrop 2007); however, this effect may vary 

by forest type (Patriquin and Barclay 2003, Tibbels and Kurta 2003). Bat activity is 
199

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

highly variable in space and time (Broders 2003, Ellison et al. 2005, Hayes 1997) 

owing to variation in prey availability, weather conditions, and proximity to roosts 

(Loeb and Waldrop 2007). 

Prescribed fire, wildfire, fire suppression, and fire management all influence 

insect populations and thus may affect bat populations. However, the influences of 

fire on insects depend on the timing of the fire with, respect to the life history of 

insects, the intensity of the fire, the fire’s rate of spread, and the area affected by the 

fire. As a result, the impact of fire and fire management on prey availability for bats 

and on the ecology of bats is generally poorly understood (Carter et al. 2002, Hayes 

and Loeb 2007).

Use of insecticides and herbicides likely influences prey availability. The influence of the chemicals applied, the ecological context, and bat-prey relationships 

have not been well studied. Insecticides can have a direct effect on prey availability; 

herbicides can have an indirect effect on insect populations by changing the abundance and composition of the plant communities (Guynn et al. 2004); however, no 

data are available on the effects of chemical treatments and bat-prey relationships 

(Hayes and Loeb 2007).

Water resources— 

Daily water loss in bats is extreme compared to other mammals, largely owing to 

the respiratory demands imposed by flight (Studier and O’Farrell 1980). Land management activities that alter bodies of water, water regimes, or water quality may 

affect bats and should be carefully evaluated. Management activities such as livestock grazing of mountain meadows, springs, and riparian zones should be managed to retain native vegetation, natural hydrological regimes, and water quality 

sources in order to retain habitat of prey species and quality sources of open water 

for drinking.

Management Considerations

The following issues were derived from the published illustrator for 

consideration by managers:

1. Large-diameter or tall snags and wildlife trees within forest stands with the 

following characteristics loose bark, dead or broken tops, natural cavities, 

or woodpecker cavities provide important habitats for bats.

2. Snags in clumped or clustered patterns across the landscape better address 

frequent roost switching that occurs with many forest-dwelling bats.

3. Snags, live cavity trees, and trees with evidence of heart rot within intact

habitat patches provide important habitat for bats. 

Large-diameter or tall 

snags and wildlife trees 

within forest stands 

with the following 

characteristics loose 

bark, dead or broken 

tops, natural cavities, 

or woodpecker cavities 

provide important 

habitats for bats.
200

GENERAL TECHNICAL REPORT PNW-GTR-907

4. Restoration of fire to forest stands can meet management objectives. Periodic 

low-intensity burning in some forest systems could help maintain a more 

open understory and reduce small-tree density that impedes bat flight. 

5. Livestock grazing of mountain meadows, areas near springs, and riparian 

zones can influence native vegetation, natural hydrological regimes, and 

water quality sources that affect habitat of prey species and quality sources 

of open water for drinking.

6. An area within a 0.21-mi radius of the roost (Keinath 2004) may be most 

suceptible to human disturbances.

Western Bluebird 

Introduction 

The western bluebird was identified as the surrogate species for the open-forest/all 

forest group because it is widely distributed in open, low-elevation forests and is 

limited by the availability of snags with existing cavities. The bluebird represents 

the array of risk factors of snags and grazing common to other members of the 

group. Some species in the group use down wood; it is assumed that if snags are 

present for the bluebird, down wood will be available as snags fall. 

Model Description

Source habitat— 

Western bluebirds are found in open coniferous and deciduous woodlands; wooded 

riparian areas; grasslands; farmlands; and burned, moderately logged, and edge 

areas with scattered trees, snags, or other suitable nest and perch sites (Guinan 

et al. 2000). This species is common in Douglas-fir and open pine forests east of 

the Cascade Range. In ponderosa pine and pine-oak forests, abundance was inversely related to canopy cover, and highest where canopy cover was <20 percent 

(Rosenstock 1996). In the western Cascade Range, this species breeds in snags in 

clearcuts and in and around the Willamette Valley, in open country with 

scattered trees and in orchards (Gilligan et al. 1994). In western Oregon, Hansen 

et al. (1995) estimated mean bluebird densities were greatest at about 10 trees/ac 

and declined to zero at about 50 trees/ac (for all stems >4 in d.b.h.) in the western 

Cascade Range. These bluebirds have shown a preference for areas with an open 

overstory and are abundant in moderately disturbed areas, including moderately 

logged forests (Franzreb 1977, Szaro 1976), and burned areas (Haggard and Gaines 

2001, Johnson and Wauer 1996, Saab and Dudley 1998), where sufficient nest sites 

and foraging perches are available. Studies on effects of fire and salvage logging 

in burned forests to western bluebirds and other cavity nesters (Guinan et al. 2000) 
201

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

have varied results. In Washington, there was a higher abundance of western bluebirds in areas of low snag density, but more nests in areas of medium to high snag 

density (Haggard and Gaines 2001). In Idaho, there were more western bluebird 

nests in areas of low to medium snag density than in higher snag density areas (Saab 

and Dudley 1998). In Arizona, forests with no salvage logging, western bluebird 

abundance was higher in severely burned than in unburned areas (Dwyer and Block 

2000). Restoration of ponderosa pine forests by thinning of dense stands, followed 

by control burns, increased western bluebird abundance, nest and fledgling success, 

and decreased predation (Gaines et al. 2007, Germaine and Germaine 2002).

We identified source habitat as follows (fig. 67): 

• Potential vegetation: Dry forests

• Cover type: Conifer mix, Douglas-fir, grand fir, ponderosa pine, western 

larch, white oak

• Tree size: All

• Canopy cover: <60 percent (includes all postfire areas as canopy closure is 

<60 percent)

Snag density— 

Nests of western bluebirds are usually found in rotted or previously excavated cavities in trees and snags, or between trunk and bark (Guinan et al. 2000). In northern 

Arizona, western bluebirds preferred snags over live trees for nesting; 70 percent of 

nests (n = 33) were found in snags. In areas where snag density was low, they found 

the birds switched to live trees for nests (Cunningham et al. 1980). 

There is often a high degree of inter- and intraspecific competition among cavity 

nesters for nest sites. Competition for nest sites has increased with the invasion of 

European starlings, house sparrows, and tree swallows (Gillis 1989, Hedges 1994, 

Herlugson 1980). On a burned site in southwestern Idaho, Lewis’ woodpeckers 

(Melanerpes lewis) frequently usurped western bluebird nests, sometimes ejecting 

nestlings (Saab and Dudley 1995). We calculated the percentage of source habitat 

within a watershed that had densities of snags >15.0 in d.b.h. in the following classes 

(per acre). These density classes were derived from Harrod et al. (1998) for open dry 

forests for eastern Washington (fig. 67).

• Low: <2.1/ac

• Moderate: 2.1 to 2.8/ac

• High: >2.8 to 3.5/ac

• Very high: >3.5/ac
202

GENERAL TECHNICAL REPORT PNW-GTR-907

Road density— 

We analyzed road density to evaluate the potential of reduced snag densities along 

roads (Bate et al. 2007, Wisdom and Bate 2008). Our snag density data are from a 

modeled dataset that did not account for road-associated factors.

We calculated the percentage of source habitat within each watershed in the 

following road density classes (fig. 67):

• Zero: <0.1 mi/mi2

• Low: 0.1 to 1.0 mi/mi2

• Moderate: 1.1 to 2.0 mi/mi2

• High: >2.0 mi/mi2

Grazing— 

Livestock grazing may contribute to reduced fire frequency in ponderosa pine forests by reducing the amount of grass that facilitated the spreading of low-intensity 

fires (Zwartjes et al. 2005). The depletion of competing grasses and lack of fire encouraged the growth of shrubs and dense stands of young conifers (Chambers and 

Holthausen 2000, Touchan et al. 1996). Dense ponderosa pine forests that resulted 

from reduced frequency of low-intensity fires are at a greater risk of stand-replacing fires (Chambers and Holthausen 2000, Touchan et al. 1996). 

Figure 67—Surrogate species assessment model for western bluebirds.
203

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

A great reduction in grass biomass owing to grazing is likely to negatively 

affect the prey base for western bluebirds (Zwartjes et al. 2005). In addition, Bull 

et al. (2001), found western bluebirds to be more abundant at ponds that were 

protected from livestock grazing than those not protected.

We categorized the amount of source habitat in an active grazing allotment 

using 10-percent increments from 0 to 100 percent, with increasing poorer habitat 

outcomes as the proportion of source habitat in an active allotment increased 

(fig. 67).

Calculations of historical conditions—

• Source habitat: 0 to 1 departure

• Snag density: High

• Road density: 0

• Grazing: 0

The relative sensitivity of WI values to the variables used in the model for 

western bluebird are shown in table 42.

Watershed scores— 

The WI values were primarily (93 percent, n = 66) low (<1.0), while three watersheds had moderate values ( ≥1 and <2), and two watersheds had high WI values 

(>2.0). The two watersheds with the greatest WI values were the Upper Chewuch 

River and the Upper Columbia-Swamp Creek. 

Habitat for western bluebirds was well below the historical median of 

source habitat in nearly all watersheds (n = 66, 92 percent). One watershed, Upper 

Columbia-Swamp creek, was above the historical median, and four were near the 

median: Lake Entiat, Okanogan River-Omak Creek, Lower Okanogan River, and 

Upper Chewuch River. 

Ten watersheds had >49,420 ac of habitat currently including the Chuwelah 

with >93,900 ac. The Wenatchee River watershed likely had the greatest decline in 

abundance of western bluebird habitat, with reduction of nearly 74,130 ac.

Table 42—Relative sensitivity 

of watershed index values 

to variables in the model for 

western bluebird

Variable Sensitivity rank

Habitat departure 1 

Snag density 2 

Grazing 3

Road density 4
204

GENERAL TECHNICAL REPORT PNW-GTR-907

Although loss of habitat had the greatest effect on the WI evaluation, snag densities were also relatively low, and road densities were relatively high. Greater than 

50 percent of the source habitat in 92 percent of the watersheds (n = 65) had low 

snag densities (<1/ac), while four watersheds had high snag densities in >50 percent 

of the source habitats: Pasayten River, Ruby Creek, Lightning Creek, and Ross 

Lake. Nearly all source habitats in these watersheds are managed by the USDA 

Forest Service. Road densities were in the high class (>2.0 mi/mi2) for >50 percent 

of the source habitat in 42 percent (n = 31) of the watersheds. About 20 percent of 

the watersheds (n = 19) had very little or none (<5 percent) of the source habitat in 

an active grazing allotment while another 25 percent had >50 percent of the source 

habitat in an active grazing allotment.

These habitat declines were similar to the findings of Wisdom et al. (2000) 

who listed declines of western bluebird habitat in the North Cascades and Northern 

Glaciated Mountains as -65 percent and -82 percent, respectively. 

Viability outcome— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. Currently, the likelihood of viability of western bluebirds is 

reduced compared to historical conditions (fig. 68). The WWI scores indicated that 

the current habitat capability for the western bluebird within the assessment area is 

18 percent of the historical capability. Dispersal across the assessment area was not 

considered an issue for this species. All five ecoregions currently contained at least 

one watershed with >40 percent of the median amount of historical source habitat. 

Thirty-two watersheds (45 percent) had >40 percent of the median amount of historical source habitat. 

The current viability outcome is a 66 percent probability of D, and a 28 percent 

probability of E. An outcome of D indicates suitable environments are low to 

moderately distributed across the historical range of the species (fig. 68). Suitable 

environments exist at low abundance relative to their historical conditions. While 

some of the subpopulations associated with these environments may be selfsustaining, there is limited opportunity for population interactions among many of 

the suitable environmental patches for species with limited dispersal ability. For 

species for which this is not the historical condition, reduction in species’ range in 

the assessment area may have resulted. These species may not be well distributed 

across the assessment area.

Historically, we estimated that 79 percent (n = 56) of the watersheds had >40 

percent of the median amount of historical source habitat, and the distribution was 

throughout all ecoregions. Therefore, historically, western bluebirds likely would 
205

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

have had primarily an A outcome with habitat broadly distributed and abundant 

(fig. 68). Raphael et al. (2001) also found a decline from historical conditions in 

their evaluation of habitats across the entire interior Columbia Basin for western 

bluebirds; however, though measured differently, not as great of a decline was 

measured. 

Management Considerations

The following issues were identified during this assessment and from the published 

literature for managers to consider:

1. Decline in the amount of source habitat of open canopy forests for western 

bluebirds throughout the dry forests across the assessment area. 

2. Loss of snags (>15 in d.b.h.) used by bluebirds for nesting and roosting. 

3. Livestock grazing may reduce the quality of the foraging habitat. 

Western Gray Squirrel

Introduction 

The western gray squirrel is a surrogate species for the open forest/pine/oak group. 

They are highly associated with ponderosa pine and oak forests with medium to 

large trees (Ryan and Carey 1995). Owing to the limited distribution of this species within the assessment area, we did not develop a surrogate species assessment 

model but provide a qualitative assessment of its habitat relationships and general 

management considerations. 

Figure 68—Current and historical viability outcomes for the western bluebird in the northeast Washington 

assessment area.

Decline in the amount 

of source habitat of 

open canopy forests 

for western bluebirds 

throughout the dry 

forests across the 

assessment area.
206

GENERAL TECHNICAL REPORT PNW-GTR-907

The western gray squirrel was once one of the most commonly encountered 

mammals in the Northwest (Bowles 1921). Wisdom et al. (2000) reported that 

source habitat for western gray squirrels showed declines in 65 percent of the 

watersheds in the North Cascade Range. Their range in Washington now consists 

of small, scattered populations that generally follow the range of Oregon white 

oak (fig. 69). There are three major subpopulations in Washington (Rodrick 1986): 

one in Klickitat County along the southern Columbia River (Linders et al. 2004), 

another in Okanogan and Chelan Counties along the northern Columbia River 

basin, and a third in Thurston and Pierce Counties in the Puget Trough (Linders and 

Stinson 2007). The population within the assessment area (Okanogan and Chelan 

Counties) occurs from the western tip of Lake Chelan near Stehekin, on the northern shore of Lake Chelan, and in the Black Canyon, McFarland, and Squaw Creek 

drainages within the Methow subbasin (Linders and Stinson 2007).

Source habitat— 

The population of gray squirrels within the assessment area is associated with 

groves of English walnut and black walnut planted by early settlers (Barnum 1975) 

Figure 69—Current distribution of western gray squirrel populations in Washington: (1) Puget Trough, (2) Klickitat 

County, and (3) Okanogan and Chelan Counties.
207

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

and with dry forests composed primarily of ponderosa pine and Douglas-fir. This 

population is small and isolated (WDFW 1993). There have been anecdotal reports 

that western gray squirrels were introduced in the Okanogan area (Linders and 

Stinson 2007). However, a recent assessment suggests that they were present historically and became isolated as populations and habitat have contracted (Linders 

and Stinson 2007). 

Risk factors— 

Risk factors for the western gray squirrel include loss of habitat from private land 

development, road-related mortality along State Highway 153 and forest roads, fire 

exclusion, improperly designed fuels-reduction projects, potential loss of habitat 

from high-severity fire, genetic effects of a small population, and disease outbreak (Cornish et al. 2001). Potential for competition from nonnative eastern gray 

squirrels and fox squirrels (Linders and Stinson 2007) has also been identified as 

a threat. The risk factors addressed in this assessment that are relevant to management of federal lands include road-related mortality on forest roads, fire exclusion 

and improperly designed fuels-reduction projects, and potential habitat loss from 

high-severity fire.

Management Considerations

The following management considerations address risk factors associated with 

western gray squirrels on National Forest System lands.

1. Road-related mortality is an important risk factor for gray squirrels.

2. Restoration of ponderosa pine forests to enhance seed production, restore 

stand structure and composition, promote the development of large tree structure and snags, and to reduce the risk of habitat loss from high-severity fire. 

The following characteristics can be used to help guide silvicultural prescriptions (based on Linders and Stinson 2007):

a. Multiaged ponderosa pine stands.

b. Low to moderate stem density with a clumped distribution of trees providing nest sites and canopy connections for arboreal travel.

c. Large (>20 in d.b.h.) ponderosa pine trees habitats.

d. Ground cover mostly of litter and grass with sparse understory of 

scattered shrubs.

e. Large-cavity trees and snags.

f. Presence of additional food species such as bigleaf maple, vine maple, 

serviceberry, or aspen.
208

GENERAL TECHNICAL REPORT PNW-GTR-907

White-Headed Woodpecker 

Introduction 

The white-headed woodpecker was chosen as a surrogate species to represent the 

medium-large trees/dry forest group. This woodpecker is associated with opencanopied ponderosa pine forests, specifically with large trees and snags that are 

important habitat components for other species in the group and family. Whiteheaded woodpeckers range across the entire Pacific Northwest in dry forests east 

of the Cascade Range of Oregon and Washington and are year-round residents.

Model Description

Source habitat— 

White-headed woodpeckers occur in open ponderosa pine or mixed-conifer forests 

dominated by ponderosa pine (Bull et al. 1986; Dixon 1995a,1995b). Dixon (1995a, 

1995b) found that population density increased with increasing volumes of oldgrowth ponderosa pine in both contiguous and fragmented sites. In addition, these 

woodpeckers may use areas that have undergone various silvicultural treatments, 

including postfire areas, if large-diameter ponderosa pines and other old-growth 

components remain (Dixon 1995a,1995b; Raphael 1981, Raphael and White 1984, 

Raphael et al. 1987). Average canopy closure at 66 nest sites was 12 percent.

Throughout the range, habitat components include an abundance of mature 

pines (with large cones and abundant seed production), relatively open canopy (50 

to 70 percent open), and availability of snags and stumps for nest cavities (Garrett et 

al. 1996). Understory vegetation is generally sparse within preferred habitat (Garrett 

et al. 1996). 

For the period 1997–2004, Frenzel (2004) found nesting success was 39 percent 

at sites with low densities of big trees, as opposed to 61 percent for nests in uncut 

stands. Uncut sites had big-tree (>21 in d.b.h.) densities >12 trees per acre. Whiteheaded woodpeckers foraged predominantly on large-diameter live ponderosa pine 

trees (Dixon 1995b). Ponderosa pine seeds are the most important vegetable food 

item for this species in Oregon (Bull et al. 1986, Dixon 1995b), especially in winter.

Source habitat was defined in this analysis as (fig. 70):

• Potential vegetation: Dry

• Cover type: Ponderosa pine is the dominant cover type in the dry natural 

vegetation group (PVG) conditions, though we included other species: western larch, conifer mix, Douglas-fir, and grand fir; as in the dry PVG, these 

types usually contain a large proportion of ponderosa pine types.

• Forest structure and size: Single- and multilayered stands with >15 in QMD 

• Canopy closure: <50 percent canopy 
209

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Snag density— 

Several studies have documented the importance of large-diameter ponderosa pine 

snags for white-headed woodpeckers (Dixon 1995a, 1995b; Milne and Hejl 1989, 

Raphael and White 1984). Of 43 white-headed woodpecker nests in central Oregon 

(Dixon 1995b), 36 were in ponderosa pine snags, 2 in ponderosa pine stumps, 2 in 

quaking aspen snags, and 1 each in live quaking aspen, white-fir snag, and the dead 

top of a live ponderosa pine tree. Most nest snags were moderately decayed. Nest 

tree size averaged 26 in d.b.h., and nest tree height averaged 46 ft; excluding one 

nest 105 ft high in a dead-topped live ponderosa pine, nest-cavity height averaged 

14.4 ft In south-central Oregon, all 16 nests studied by Dixon (1995a) were in completely dead substrates (37 percent in snags, 56 percent in stumps, and 6 percent in 

leaning logs). Mean size of nest trees was 31.5 in d.b.h., and nest tree height averaged 10 ft. 

Frenzel (2004) found that of 405 nests of white-headed woodpeckers, all but 12 

were in completely dead trees. Mean size of nest trees was 27 in d.b.h. (n = 405), 

mean canopy closure at nest sites was 11.0 percent, and density of large trees >21 in 

d.b.h. was 61 trees/ac. 

We calculated the percentage of area of source habitat within each watershed 

that had snag (>20 in d.b.h.) densities in the following classes based on data from 

Harrod et al. (1998) of (fig. 70):

• Low: <1.0/ac 

• Moderate: 1.0 to 1.3/ac 

• High: 1.3 to 1.5/ac

• Very high: >1.5/ac

Road density— 

We included a road density variable to account for likely reduced snag densities 

along roads (Bate et al. 2007, Wisdom and Bate 2008). We calculated road densities 

in four classes (fig. 70):

• Zero: - <0.1 mi/mi2

 open roads in a watershed

• Low: 0.1 to 1.0 mi/mi2 open roads in a watershed

• Moderate: 0.1 to 2.0 mi/mi2 open roads in a watershed

• High: >2.0 mi/mi2 open roads in a watershed

Shrub cover— 

Frenzel (2004) found that shrub cover was a significant variable in predicting 

nest success. Nest sites with <5 percent shrub cover had the highest mean nesting 

success of 61 percent. Nest success with shrub cover >5 percent had a mean nest 

success of 42 percent.
210

GENERAL TECHNICAL REPORT PNW-GTR-907

Smith (2002) reported that densities of chipmunks in ponderosa pine habitat 

in central Oregon increased with shrub cover, and densities of golden-mantled 

ground squirrels increased with amounts of down wood. Both of these species are 

nest predators of white-headed woodpeckers (Mellen-McLean et al. 2013), suggesting that higher levels of shrubs and woody debris may lead to increased levels of 

predation. 

Using gradient nearest-neighbor shrub density data, we calculated the percentage of source habitat with high (>15 percent) and low (<15 percent) shrub density 

per watershed. Although the research suggest 5 percent cover (Mellen-McLean et 

al. 2013), after reviewing the data we had on shrub density, we felt the 15 percent 

shrub density from the data-set was likely representing areas we knew as having 

closer to 5 percent shrub density.

Figure 70—Surrogate species assessment model for white-headed woodpeckers.
211

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Calculation of historical conditions—

• Source habitat: 0 to 1 departure

• Snag density: High

• Road density: 0

• Shrub density: Low

The relative sensitivity of the WI values to variables used in the model for 

white-headed woodpecker are shown in table 43.

Model evaluation— 

We evaluated the model for white-headed woodpeckers using 88 documented occurrences compiled by Mellen-McLean et al. (2013) and an equal number of random 

points. We did not find a statistical difference (t = 1.97, P = 0.78) between the mean 

WI derived from points of the occurrences (1.6) and random points (1.7). We believe 

that the WI values were so low for all watersheds that there was an insufficient distribution of values to make our statistical approach meaningful.

Assessment Results

Watershed scores— 

Historically, all but one watershed (Ashnola) contained source habitat for the whiteheaded woodpecker. Currently, 97 percent (n = 69) had a high departure from the 

historical median amount of habitat across all watersheds (fig. 71). Okanogan RiverBonaparte Creek, and Okanogan River-Omak Creek were currently at or above the 

historical median amount of habitat. 

We assumed in this analysis that if the amount of source habitat in a watershed 

was reduced to <40 percent of the historical amount, the ecological function of 

the remaining source habitat to provide for the viability of the surrogate species 

was greatly diminished. For the white-headed woodpecker, this value is 3,330 ac. 

Table 43—Relative sensitivity 

of watershed index values to 

variables in the model for whiteheaded woodpeckers

Variable Sensitivity rank 

Habitat departure 1

Snag density 2

Road density 3

Shrub density 4
212

GENERAL TECHNICAL REPORT PNW-GTR-907

Figure 71—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for white-headed woodpeckers by watershed in the northeast Washington assessment area.
213

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Historically, 55 watersheds met this condition. Currently, only 20 percent of the (n 

= 14) watersheds contained >40 percent of the historical median amount of habitat. 

Watersheds with the most source habitat currently were the Okanogan RiverBonaparte Creek (18,090 ac), Okanogan River-Omak Creek (15,400 ac), West Fork 

Sanpoil (12,130 ac), and the Middle Methow River (10,030 ac) (fig. 71). 

The watersheds with the greatest potential habitat on National Forest System 

lands are the Lower Chewuch River, Lower Lake Chelan, Lower Methow, Middle 

Methow, and Boulder/Deadman. Boulder/Deadman has >64,250 ac of potential 

habitat on National Forest System lands, but <740 ac currently that was suitable. 

The watersheds with the greatest amount of current source habitat managed by the 

Forest Service were the Middle Methow River (8,900 ac) and the West Fork Sanpoil 

(5,095 ac). 

The majority of watersheds (n = 63, 86 percent) had >50 percent of the source 

habitat with low (<1.0 snags/acre) snag densities. About on-third (n = 24) of the 

watersheds had high road densities in more than 50 percent of the dry forests, 

while 10 (14 percent) watersheds had >50 percent of the dry forests having zero 

road densities. Most watersheds had high shrub densities in source habitat (n = 65, 

90 percent), which along with the propensity of high road densities and low snags 

contribute to lower WI values (poorer habitat quality).

Only two watersheds had a WI score that was not low (>1): Okanogan RiverBonaparte Creek (2.0) and Okanogan River-Omak Creek (1.5) (fig. 71). All other 

watersheds had low WI values (<1.0) primarily owing to loss of habitat. 

Viability outcome— 

The VOI model incorporated the WWI scores (described earlier) and a habitat distribution index. The WWI scores indicated that the current habitat capability for the 

white-headed woodpecker within the assessment area is 21 percent of the historical 

capability. Dispersal across the assessment area was not considered an issue for this 

species. Two of five ecoregions currently contained at least one watershed with >40 

percent of the median amount of historical source habitat. Fourteen watersheds (20 

percent) had >40 percent of the median amount of historical source habitat currently. We estimated the current viability outcome is a 50 percent probability of D and 

47.5 percent probability of E, indicating habitat was isolated and occurs at very low 

abundance (fig. 72). 

We estimated that historical conditions were much different for this woodpecker. Dispersal across the assessment area was not considered an issue for this 

species. Five of five ecoregions and 55 (77 percent) of the watersheds contained 

>40 percent of the median amount of habitat historically. 
214

GENERAL TECHNICAL REPORT PNW-GTR-907

Historically, we estimated that 77 percent of the watersheds (n = 55) contained source habitat >40 percent of the historical median and was widespread 

throughout the assessment area. The viability outcome historically was estimated 

to be 76 percent A and 16 percent B, indicating a broad distribution of abundant 

habitat (fig. 72).

In summary, under historical conditions, white-headed woodpeckers were 

likely well distributed throughout the assessment area; currently, they are likely not 

well distributed and at risk of extirpation. 

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Decline in the amount of source habitat for white-headed woodpeckers 

throughout dry forests across the assessment area.

2. Low levels of large-diameter (>21 in d.b.h.) snags within the majority of 

watersheds assessed within the planning area.

3. High road densities in dry forest in 32 percent of the watersheds that may 

contribute to loss of large snags.

4. High shrub densities in existing habitat that may lead to higher predation.

5. The sustainability of dry forest habitats that have experienced several 

decades of fire exclusion and are susceptible to stand-replacing fire events.

Figure 72—Current and historical viability outcomes for the white-headed woodpecker in the northeast 

Washington assessment area.

Decline in the 

amount of 

source habitat 

for white-headed 

woodpeckers 

throughout dry 

forests across the 

assessment area.
215

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Wilson’s Snipe

Introduction

The wilson’s snipe was chosen as a surrogate species to represent habitats in the 

marsh/wet meadow group of the wetland family. Wilson’s snipes have one of 

the widest distributions for species in these habitats. However, habitats for species in this group were not abundant on National Forest System lands in eastern 

Washington, and they were patchily distributed across the assessment area with 

concentrations in the central and eastern portions (Smith et al. 1997). Wilson’s 

snipes generally forage in shallow water and mudflats; major risks to the species 

are draining, filling, and degradation of marshes; and environmental contaminants. 

Although grazing by domestic livestock was considered a risk for several species 

associated with these habitats, these risks varied by species and by intensity and 

season of grazing, and so grazing may not have always had a negative impact. 

Wilson’s snipes are year-round residents of the assessment area (Mueller 1999); this 

assessment was for nesting habitat.

Model Description

Source habitat— 

Breeding habitat of Wilson’s snipes has been characterized as sedge bogs, fens, 

and alder or willow wetlands (McKibben and Hofmann 1985, Tuck 1972). Banner 

and Schaller (2001) interpreted these associations to equate to palustrine emergent 

(PEM) and palustrine scrub shrub (PSS) wetlands as described by Cowardin et al. 

(1979). We used those definitions and maps in the National Wetlands Inventory to 

describe and delineate source habitat for this analysis where they occurred in vegetation zones shrub-steppe, ponderosa pine, Douglas-fir, and grand fir (fig. 73).

Wetland size— 

Gibbs et al. (1991) reported a positive relationship between the presence of snipes 

during the breeding season and size of wetland (i.e., <1 to >50 ac). Banner and 

Schaller (2001) suggested that wetlands <7 ac had limited value as habitat for snipe. 

Based on those findings, we characterized wetland size with the following classes 

(fig. 73):

• Small: <25 ac mean size of PEM or PSS wetlands within a watershed.

• Large: ≥25 ac mean size of PEM or PSS wetlands within a watershed.
216

GENERAL TECHNICAL REPORT PNW-GTR-907

GIS databases used—

• National Wetlands Inventory

• Vegetation Zone

Calculation of historical conditions—

• Departure of source habitat from HRV: 0.5

• Wetland size: Class large

• Current amount of habitat in each watershed was increased by 30 percent.

The relative sensitivity of WI values to the variables used in the model for 

Wilson’s snipes are shown in table 44.

Assessment Results

Watershed scores— 

Sixty-two of 72 watersheds within the assessment area provided habitat for Wilson’s 

snipes (fig. 74). All watersheds with habitat have experienced habitat loss from 

historical conditions (fig. 74). Thirty-four percent (n = 21) of watersheds had high 

WI scores (>2.0); 66 percent (n = 41) of watersheds had moderate WI scores (>1.0 to 

<2.0) (fig. 74). Factors that influenced the WI scores included the amount of source 

habitat (fig. 74). Gibbs et al. (1991) and Banner and Schaller (2001) reported positive 

Figure 73—Surrogate species assessment model for Wilson’s snipes.
217

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 44—Relative sensitivity 

of watershed index values to 

variables in the model for Wilson’s 

snipes

Variable Sensitivity rank

Habitat departure 1

Wetland size 2

Figure 74—Current amount of (A) source habitat (acres), (B) current habitat departure, (C) watersed index, and (D) 

habitat condition for Wilson’s snipes (WISN) by watershed in the northeast Washington assessment area (NEWA).
218

GENERAL TECHNICAL REPORT PNW-GTR-907

relationships between the presence of snipe and size of wetland. Thirty-four percent 

(n = 21) of the watersheds had small mean wetland size (<25 ac); 66 percent (n = 41) 

had large mean wetland size (≥25 ac).

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), and a habitat 

distribution index. The WWI scores indicated that the current habitat capability for 

Wilson’s snipe within the assessment area is 66 percent of the historical capability. 

Dispersal across the assessment area is not considered an issue for this species owing to their relatively high mobility. All five ecoregions contain at least one watershed with >40 percent of the median amount of historical source habitat (median 

was calculated across all watersheds with source habitat). Fifty-eight percent (n = 

42) of the watersheds currently have >40 percent of the median amount of historical source habitat. Under those circumstances, there is a 28 percent probability that 

the current viability outcome for Wilson’s snipes is A and a 54 percent probability 

of outcome B, indicating habitat is broadly distributed and abundant, but there are 

gaps where suitable environments are absent or only present in low abundance (fig. 

75). Other species associated with habitats in the marsh/wet meadow group of the 

wetland family likely have similar outcomes.

Historically, dispersal across the assessment area was not considered an issue 

for this species. All ecoregions contained at least one watershed with >40 percent 

of the median amount of historical source habitat (median was calculated across 

all watersheds with source habitat). Forty-two percent (n = 30) of watersheds had 

Figure 75—Current and historical viability outcomes for Wilson’s snipes in the northeast Washington 

assessment area.
219

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

>40 percent of the median amount of historical source habitat. Under those circumstances, there was a 57 percent probability that the historical viability outcome 

for Wilson’s snipes was A, and a 27 percent probability that the historical viability 

outcome was B, indicating habitat was broadly distributed and abundant (fig. 75).

In summary, under historical conditions, Wilson’s snipes and other species 

associated with habitats in the marsh/wet meadow group of the wetland family were 

likely well distributed throughout the assessment area. Currently, they continue 

to be well distributed, but there are gaps where suitable environments are absent 

or only present in low abundance (e.g., high-quality habitats are clustered in the 

eastern and central portions of the assessment area). However, these habitats are 

estimated to be large enough and close enough together to permit dispersal among 

subpopulations and to allow the species to potentially interact as a metapopulation 

in those areas. However, some subpopulations are so disjunct or of such low density 

that they are essentially isolated from other populations (e.g., southwestern portion 

of the assessment area).

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. Loss and degradation of wetland habitats.

Wolverine

Introduction

The wolverine was selected as a surrogate species for the habitat generalist group. 

It is sensitive to risk factors that can cause disturbance (Copeland et al. 2007, Krebs 

et al. 2007) as are the other species in this group. Reports of wolverines within the 

assessment area have been steadily increasing since the 1960s (Aubry et al. 2007, 

Edelmann and Copeland 1999, Johnson 1977). Currently, their distribution appears 

to include the Cascade Range, Kettle Range and Selkirk Mountains, although their 

density is likely low (Aubry et al. 2007, Edelmann and Copeland 1999). Wolverines 

are year-round residents within the assessment area, and this assessment represents 

their year-round habitat use.

Model Description

Source habitat— 

Montane coniferous forests, suitable for winter foraging and summer kit rearing, may only be useful if connected with subalpine cirque habitats required for 

natal denning, security areas, and summer foraging (Copeland 1996, Copeland et 
220

GENERAL TECHNICAL REPORT PNW-GTR-907

al. 2010). Similar to other large mammalian carnivores (e.g., Ursus arctos, Canis 

lupus), the current distribution of wolverines is likely determined by the intensity of 

human settlement, and in addition, the persistence of spring snow cover (Aubry et 

al. 2007, Copeland et al. 2010) rather than by vegetation type or topography (Banci 

1994, Carroll et al. 2001, Kelsall 1981). 

Several researchers have documented the effects of roads on wolverines and 

their habitat and have included roads in models of source habitat (Carroll et al. 2001, 

Copeland et al. 2007, Krebs et al. 2007, Raphael et al. 2001, Rowland et al. 2003, 

Wisdom et al. 2000). Carroll et al. (2001) found areas with road densities <1 mi/mi2

to be strongly correlated with the presence of wolverine. Rowland et al. (2003) in a 

test of the Raphael et al. (2001) model found that road density was a better predictor 

than habitat amount of wolverine abundance when applied at the watershed scale 

(such as our WI model). Thus, we incorporated road densities into our definition of 

source habitat. To identify source habitat for this species, we limited the analysis of 

current source habitat to those areas with road densities of <1.0 mi/mi2. This road 

density classification was developed from Gaines et al. (2003).

We included most cover types and structural stages in montane forest, subalpine forest, alpine tundra, as did Wisdom et al. (2000) and Raphael et al. (2001). 

These cover types also coincide with areas where there is a higher likelihood of 

persistent spring snow cover (Copeland et al. 2010). We used the following variables 

to identify wolverine source habitat within the assessment area (fig. 76):

• Road density: Areas with road densities <1.0 mi/mi2

• Cover types: Alpine, parkland, subalpine fir, Pacific silver fir, Engelmann 

spruce, western hemlock, western redcedar, mountain hemlock, lodgepole 

pine, western larch, mixed conifer, Douglas-fir, and grand fir. We did not 

include low-elevation cover types such as ponderosa pine and shrub-steppe.

Mean patch size— 

Banci (1994) identified the need for large areas of the appropriate vegetation types 

and with low human use to provide for the conservation of wolverine. We evaluated 

the relative size of the areas of source habitat within a watershed by computing a 

mean patch size and classified the data into three classes, representing high, medium, and low. Our assumption was that the greater the mean patch size, the more 

conservation value the watershed would have for wolverine. We categorized the 

mean patch size as follows (fig. 76):

• Low mean patch size: <2 mi2

• Moderate mean patch size: 2 to 4 mi2

• High mean patch size: >4 mi2
221

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Potential den habitat— 

Natal dens are typically above or near tree line, require snow depths of 3 to 10 ft 

that persist into spring, and are in proximity to rocky areas such as talus slopes or 

boulder fields (Copeland 1996, Copeland et al. 2010). The predictive habitat model 

for wolverine developed by Carroll et al. (2001) was improved when alpine cirque 

habitat was added as a variable as a surrogate to denning habitat. We modeled 

potential den habitat by using land type associations (Ha7, Ha8, Hb9, Hi9) that 

represented alpine and subalpine boulder fields and talus slopes (USFS 2000) 

(fig. 76). The amount of potential wolverine den habitat was categorized as follows:

• Zero: 0 ac of potential den habitat

• Low: >0 to 3,700 ac of potential den habitat

• Moderate: >3,700 to 8,650 ac of potential den habitat

• High: >8,650 ac of potential den habitat

Winter habitat effectiveness— 

Copeland (1996) and Krebs and Lewis (1999) documented the potential for disturbance to wolverine natal dens because of late winter to spring snowmobile and other 

winter recreation activities. We assessed the potential effects of winter recreation 

Figure 76—Surrogate species assessment model for the wolverine.
222

GENERAL TECHNICAL REPORT PNW-GTR-907

on the effectiveness of wolverine habitat by overlaying winter recreation routes onto 

wolverine habitat and calculating the density of these routes (fig. 76). This was an 

underestimate of the impacts of winter activities as other recreation routes were 

present in the assessment area but not in our digital inventory. We categorized the 

effects of winter recreation activities on wolverine habitat as follows (fig. 76):

• Low habitat effectiveness: >25 percent of habitat with winter route densities 

>2.0 mi/mi2

• Moderate habitat effectiveness: >25 percent of habitat with winter route 

densities >1.0 mi/mi2

• High habitat effectiveness: <25 percent of habitat with winter route 

densities <1.0 mi/mi2

Calculations of historical conditions— 

Source habitat: Area of alpine, parkland, subalpine fir, pacific silver fir, Engelmann 

spruce, western hemlock, western redcedar, mountain hemlock, lodgepole pine, 

western larch, mixed-conifer, Douglas-fir, and grand fir cover types.

• Patch size: Calculated average patch size without the influence of roads

• Den habitat: Same as the current amount

• Winter habitat effectiveness: High 

The relative sensitivity of WI values to variables used in the model for wolverine are shown in table 45.

Model evaluation— 

We derived the mean WI value from 64 points where occurrences of wolverines 

were confirmed and compared it with the mean WI value from 63 random points. 

The mean WI for the occurrence points (2.01) was significantly higher (t = 1.98, P 

= 0.0001) than the mean derived from the random points (1.58) indicating that our 

model identified suitable environments within watersheds for wolverines.

Table 45—Relative sensitivity of watershed 

index values to variables in the model for 

the wolverine

Model variables

Order of variable 

weighting

Source habitat 1

Patch size 2

Den habitat 3

Winter habitat effectiveness 4
223

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Assessment Results

Watershed scores— 

Currently, five (7 percent) of the watersheds have high WI scores ( >2.0). The 

remaining additional 67 (93 percent) watersheds had WI scores with moderate 

(between 1.0 and 2.0) scores (fig. 77). The lower scores were largely owing to the 

influence of roads on the loss of source habitat for wolverines. In our model, areas 

with high road densities reduced the availability of source habitat and the patch size 

of source habitat. Areas with high road densities have been shown to have lower 

probabilities of wolverine occurrence (Caroll et al. 2001, Rowland et al. 2003). 

Figure 77—Current amount of (A) source habitat (acres) for, (B) current habitat departure, (C) watershed index, and (D) 

habitat condition class for wolverine, (WOLV) by watershed in the northeast Washington assessment area (NEWA).
224

GENERAL TECHNICAL REPORT PNW-GTR-907

All of the watersheds with high (>2.0) WI scores occurred within the OkanoganWenatchee National Forest portion of the assessment area and are largely a result 

of the presence of wilderness and roadless areas. These results are similar to those 

reported in other efforts to evaluate wolverine habitat. Raphael et al. (2001) evaluated wolverine habitat across the Columbia Basin and showed that the best habitat 

occurred along the Cascade Crest within the Okanogan-Wenatchee National Forest, 

while much lower scores associated with poorer habitat were found on the Colville 

National Forest. Similarly, Singleton et al. (2002) did not identify any “habitat 

concentration areas” for wolverine on the Colville National Forest, with the exception of a small area in the northeast portion of the Lower Pend Oreille watershed. 

However, they did identify important habitat linkages across the Kettle Crest and 

the Okanogan Highlands (Singleton et al. 2002).

This assessment of the amount of source habitat currently suggests declines 

from historical conditions. Our analysis found that 54 percent (n = 39) of the watersheds were near the historical median of source habitat, and 46 percent (n = 33) 

were below the historical median (fig. 77). Watersheds with the most source habitat 

(>98,800 ac) included Ross Lake, Pasayten River, Stehekin River, Middle Pend 

Oreille River, Lower Chewuch River, North Lake Roosevelt, Upper Pend Oreille 

River, Upper Chewuch River, Boulder/Deadman, and Lower Pend Oreille River. 

Two of the five watersheds with the high WI scores are in this group: Pasayten 

River and Upper Chewuch River.

Other factors that influenced the WI scores included the availability of alpine 

cirques used for denning habitat (Copeland 1996). One-half of the watersheds 

(n = 36) did not contain any potential wolverine denning habitat, while 14 percent 

(n = 10) included moderate to high levels of potential wolverine denning habitat. 

Watersheds with the greatest amount of potential denning habitat included Lost 

River, Pasayten, Twisp River, Upper Chewuch, and Upper Methow.

Currently, the influence of winter recreation routes has little effect on the 

potential wolverine denning habitat that we modeled because much of the denning 

habitat we identified occurred in wilderness areas or in remote areas that are difficult to access. However, there are winter recreation routes not in our inventory that 

may influence denning habitat. For example, helicopter skiing occurs within the 

Upper Methow watershed, which currently has a high amount of potential denning 

habitat.

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier), a habitat distribution index, and a habitat connectivity or permeability index. The WWI provides a 
225

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

relative measure across watersheds of the potential capability of the watershed to 

contribute to the viability of the surrogate species. The WWI scores indicated that 

the current habitat capability for wolverine within the assessment area is 74 percent 

of the historical capability. This is largely due to the influence of human activities 

(roads) on wolverine habitats.

Currently, 72 percent (n = 52) of the watersheds contain source habitat amounts 

above 40 percent of the historical median, whereas historically, 86 percent (n = 62) 

were above this minimum habitat amount. The watersheds with >40 percent were 

distributed across all of the five ecoregions both currently and historically. 

Because wolverines are highly mobile, we evaluated the contribution of dispersal habitat in the viability outcome model. Currently, dispersal habitat suitability of 

the assessment area for wolverine was rated as moderate to high. Across the assessment area, 8 percent of the watersheds rated as low dispersal habitat suitability, 

48 percent rated as moderate, and 44 percent rated as high. Historically, dispersal 

habitat was projected to be high across the majority of the assessment area. These 

results are similar to other efforts to evaluate the dispersal habitat suitability for 

wolverine in the same general area (Singleton et al. 2002, WWHCWG 2010). 

Singleton et al. (2002) identified “fracture zones” that occur within the assessment 

area and warrant careful management attention. Fracture zones were defined as 

areas with considerable disruption of suitable habitat conditions for wolverine 

dispersal. Fracture zones included Stevens Pass, Snoqualmie Pass, and the portion 

of the assessment area from the Okanogan-Kettle-Selkirk Mountains where areas in 

public ownership are more limited and disjunct. 

The current viability outcome for the assessment area is a 68 percent probability of B, which indicated that suitable environments for the wolverine were broadly 

distributed and of high abundance, but there were gaps where suitable environments 

are absent or only present in low abundance (fig. 78). However, the disjunct areas 

of suitable environments are typically large enough and close enough together 

to permit dispersal among subpopulations and to allow the species to potentially 

interact as a metapopulation. Historically, the viability outcome for wolverine had a 

probability of 79 percent A where suitable environments were more broadly distributed or of high abundance (fig. 78). In addition, the suitable environments were 

better connected, allowing for interspecific interactions. Our analysis indicated 

some reduction in the availability of suitable environments for the wolverine, and 

likely other species in the human disturbance group, occurred in the assessment 

area compared to the historical distribution and condition of their habitats.
226

GENERAL TECHNICAL REPORT PNW-GTR-907

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers: 

1. High road densities have reduced the amount of source habitat (Raphael et 

al. 2001, Wisdom et al. 2000) in the assessment area.

2. Habitat connectivity between patches of existing source habitats remains 

high north and south along the crest of the Cascade Range with exceptions 

along major highway corridors (Singleton et al. 2002, WWHCWG 2010). 

More concern about habitat connectivity for wolverines occurs between the 

North Cascade Range and Selkirk Mountains in the northeast portion of the 

assessment area where public lands are more limited (Singleton et al. 2002).

Wood Duck 

Introduction

The wood duck was selected as a surrogate species for the riparian/large tree or 

snag/open water group to represent cavity-nesting species associated with forested 

riparian areas (streams, wetlands, ponds, lakes). The wood duck represents the 

cavity-nesting ducks in this group; unlike the other ducks in the group, wood ducks 

are widespread throughout Oregon and Washington. The common merganser is 

an exception because this species does not always nest in tree cavities. Breeding 

areas for wood ducks occurs primarily within western Washington; however, 

Figure 78—Current and historical viability outcomes for the wolverine in the northeast Washington 

assessment area.

High road densities 

have reduced the 

amount of source 

habitat in the 

assessment area.
227

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

known breeding areas are patchily distributed across eastern Washington within the 

assessment area (Smith et al. 1997). Wood ducks typically winter farther south than 

Washington; however, significant wintering numbers can be found in the Yakima 

Valley (Lewis and Kraege 2000).

Model Description

Source habitat— 

Wood ducks nest primarily in late-successional forests and riparian areas adjacent 

to low-gradient rivers, lakes, and wetlands (Lewis and Kraege 2000). At least 10 ac 

of wetland or other aquatic habitat should be available in a contiguous unit (USGS 

2004) for successful nesting. Wood ducks nest almost exclusively in tree cavities, 

which offer protection from weather and predators (Peterson and Gauthier 1985, 

Robb and Bookhout 1995, Soulliere 1988). They are secondary cavity nesters, using cavities created by large woodpeckers or by decay or damage to the tree. Cavity 

use is dependent upon the proximity of nesting habitat and brood habitat (Robb and 

Bookhout 1995). Shallow wetlands within 0.5 mi of cavities provide optimal brood 

habitat (Lewis and Kraege 2000).

We modeled source habitat for wood ducks using a combination of forest 

structure and tree size data along with information from the National Wetlands 

Inventory. We used the following specific variables to map source habitat within 

each watershed (fig. 79):

• Cover type: All cover types at all elevations

• Tree structure and size: Single/multistory, >15 in QMD, 0.5 mi from a suitable waterbody or wetland complex as described below

• National Wetlands Inventory: Waterbodies and wetland complexes (PFO, R2, 

R3) >10 ac

Habitat departure was calculated as estimated as for other wetland-associated 

species by assuming that source habitat has been reduced from historical levels by 30 

percent thus the habitat departure variable to assess current conditions was set at -2.

Snag habitat— 

Soulliere (1988) suggested that trees needed to be >12 in d.b.h. to provide a suitable 

cavity for wood ducks to nest in. The optimal density of potential nest trees described by Sousa and Farmer (1983) was five per acre. We used snag data from forest inventory plots to assess the availability of suitable nesting habitat within source 

habitat (fig. 79). We used the following categories to assess the size and density of 

snag habitat on source habitat quality within each watershed.
228

GENERAL TECHNICAL REPORT PNW-GTR-907

• Low habitat quality: <5.0 snags/ac >12 in d.b.h.

• Moderate habitat quality: 6.0 to 7.0 snags/ac >12 in d.b.h.

• High habitat quality: 7 to 10 snags/ac >12 in d.b.h.

• Very high habitat quality: >10 snags/ac >12 in d.b.h.

Habitat effectiveness— 

Human disturbance has been shown to affect productivity of wood ducks by causing nest abandonment, egg mortality from exposure, increased predation of eggs 

and hatchlings, depressed feeding rates, and avoidance of otherwise suitable habitat 

(Hamman et al. 1999, Havera et al. 1992, Lewis and Kraege 2000). We used the 

waterfowl habitat disturbance index (Gaines et al. 2003) to evaluate the potential effects of human disturbance associated with roads and trails on source habitat. Open 

roads and trails were buffered by 820 ft and then overlaid with maps of source habitat to estimate the proportion of source habitat within a zone of influence in each 

watershed (fig. 79). We then categorized these potential effects as follows:

• Low habitat effectiveness: >50 percent of the source habitat in a zone of 

influence

Figure 79—Surrogate species assessment model for the wood duck.
229

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

• Moderate habitat effectiveness: 30 to 50 percent of the source habitat in a 

zone of influence

• High habitat effectiveness: <30 percent of the source habitat in a zone of 

influence

The relative sensitivity of WI values to the variables used in the model for wood 

duck are shown in table 46.

Assessment Results

Watershed scores— 

There were two (3 percent) watersheds that had WI scores >2.0, 32 (47 percent) 

with WI scores from 1.0 to 2.0, and 34 (50 percent) were degraded with scores <1.0. 

Watersheds with the most source habitat (>1,240 ac) included Lower Chewuch, 

Middle Yakima, Upper Pend Oreille, Entiat, Stehekin, Upper Yakima, Chiwawa, 

Wenatchee, and Middle Methow Rivers. The median amount of source habitat 

across all watersheds with at least some habitat (68 watersheds) was 368.2 ac.

The availability of snag habitat (>12 in d.b.h.) within source habitat was very 

high in 6 (9 percent) of the watersheds, high in 4 (6 percent) of the watersheds, 

moderate in 15 (22 percent) of the watersheds, and low in 43 (63 percent) of the 

watersheds. Snag habitat is important for nesting wood ducks, and the majority of 

the watersheds had low availability of this critical habitat component.

Habitat effectiveness was high in three watersheds (4 percent), moderate in 10 

(15 percent) watersheds, and low in 55 (81 percent) of the watersheds. Habitat effectiveness may be restored through management of human access. This would also 

reduce the loss of snags from roadside hazard tree removal and firewood cutting, as 

well as reduce the potential of negative effects associated with human disturbance 

at nest sites.

Table 46–Relative sensitivity of 

watershed index values to variables 

in the model for wood ducks

Model variables

Order of variable 

weighting

Source habitat 1

Snag density 3

Habitat effectiveness 2
230

GENERAL TECHNICAL REPORT PNW-GTR-907

Viability outcome scores— 

The VOI model incorporated the WWI scores (described earlier) and a habitat distribution index. The WWI score indicated that the current habitat capability for wood 

ducks within the assessment area is 41 percent of the historical capability. This 

reduction occurred because of loss of wetland source habitat and low levels of snag 

habitat within source habitat in many watersheds.

Forty percent of the historical median amount of source habitat across all 

watersheds with at least some habitat was 156.9 ac. A total of 40 (50 percent) of the 

watersheds within the assessment area met this habitat minimum. The watersheds 

with >40 percent were distributed across all five ecoregions.

Historically, all five ecoregions contain at least one watershed with >40 percent 

of the median amount of historical source habitat (median was calculated across 

all watersheds with source habitat). Forty-seven (69 percent) watersheds had >40 

percent of the median amount of historical source habitat.

Currently, there is a 72 percent probability that the viability outcome for wood 

duck within the assessment area is C (fig. 80), suggesting that suitable conditions 

for the wood duck are likely well distributed in only a portion of the assessment 

area. Gaps exist where suitable environments are either absent or present in low 

abundance. Historically, there was a 71 percent probability of outcome A and a 19 

percent probability of outcome B (fig. 80), where suitable environments were more 

Figure 80—Current and historical viability outcomes for the wood duck in the northeast Washington 

assessment area.
231

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

broadly distributed or at higher abundance. This resulted in suitable environments 

that were better connected. A reduction in suitable environments for the wood duck, 

and likely other species in the riparian/large tree or snag/open water group, has 

occurred in the assessment area compared to historical conditions.

Management Considerations

The following issues were identified during this assessment and from the published 

literature for consideration by managers:

1. The area of wetland habitats has experienced significant declines across the 

region and in some portions of the assessment area.

2. The influence of human activities within wood duck source habitat 

has reduced the availability of nesting habitat (large snags) and habitat 

effectiveness.
232

GENERAL TECHNICAL REPORT PNW-GTR-907
233

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Chapter 3: Multispecies Conservation

Introduction

In this chapter, we present the procedures used to address multiple species using 

results of our individual species assessments. Wisdom et al. (2002) described a 

process for assessing the habitat conditions for groups of species in order to identify 

a habitat network for terrestrial wildlife in the interior Columbia Basin. We modified the approach of Wisdom et al. (2002) to integrate information from individual 

surrogate species into multispecies assessments. For each surrogate species, we 

determined the condition of the habitat in each watershed, which led to a conservation emphasis for the surrogate species in each watershed. Conservation emphases 

consisted of protection, restoration, connectivity, or combinations of each of these. 

We then created a matrix of all surrogate species and conservation emphasis that 

addressed their habitat and risk factors for multiple species (table 47). The steps we 

used to go from individual species to multiple species are described below:

Step 1: Determine habitat conditions for each 5th-field watershed for each 

surrogate species. The habitat conditions were completed as part of the individual 

species assessments (see chapter 2) and are based on the watershed index (WI) 

scores, the current amount of source habitat relative to reference conditions, habitat 

dispersal suitability (for some species), and the amount of source habitat in federal 

ownership within a watershed.

Step 2: We grouped surrogate species by whichever conservation emphasis that 

would best address their habitat and risk factors (table 47). We then used individual 

surrogate species assessments to identify a habitat condition that best addressed 

the group for each watershed. We used the most limited (fewest watersheds in good 

condition) species in the group to identify a habitat condition for each watershed. 

For example, if species A had more watersheds with habitat condition 1a (which 

means relative good conditions) than species B, we used species B to identify priority watersheds for protection, restoration, or connectivity.

Step 3: We then identified a single set of priority watersheds and management 

considerations to address multiple species. By using a combination of management 

considerations and a set of priority watersheds, managers have important information and tools to contribute to the viability of surrogate species.

Step 4: The final step, which is outside the scope of this assessment, will be to 

integrate the results of this assessment with other resources through an interdisciplinary planning process.
234

GENERAL TECHNICAL REPORT PNW-GTR-907

Table 47—Conservation emphasis areas to improve viability 

outcomes for surrogate speciesa (continued)

Conservation emphasis areas to 

improve surrogate species viability

Surrogate species

Aquatic and riparianSnag and down woodMoist forest Mesic-dry forestPostfire harvestHuman accessDomestic grazingInvasive species

American marten X X X X

Bald eagle X X X X X

Bighorn sheep X X X

Black-backed woodpecker X X X

Canada lynx X X X X

Cassin’s finch X X X

Columbia spotted frog X X X X

Eared grebe X X X

Fox sparrow X

Fringed myotis X X X X X X

Golden eagle X X X X

Harlequin duck X X X X

Larch mountain salamander X

Lark sparrow X

Lewis’s woodpecker X X X X

MacGillivray’s warbler X X X

Marsh wren X X

Northern bog lemming X X X

Northern goshawk X X X X

Northern harrier X X X

Peregrine falcon X X

Pileated woodpecker X X X X

Sage thrasher X X X

Tailed frog X X X X

Tiger salamander X X X X

Townsend’s big-eared bat X X X
235

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 47—Conservation emphasis areas to improve viability 

outcomes for surrogate speciesa (continued)

Conservation emphasis areas to 

improve surrogate species viability

Surrogate species

Aquatic and riparianSnag and down woodMoist forest Mesic-dry forestPostfire harvestHuman accessDomestic grazingInvasive species

Western bluebird X X X X

Western gray squirrel ? X X X X

Water vole X X

White-headed woodpecker X X X X

Wilson’s snipe X

Wolverine X

Wood duck X X X

a

 Species were selected and highlighted to guide the development of conservation emphasis 

and management considerations.

Conservation Emphasis Areas

We used the information from individual species assessments to identify eight 

broad conservation emphasis areas that address habitat and risk factors for multiple 

surrogate species. The multispecies emphasis include two parts: management 

considerations and a prioritized list of watersheds. We prioritized watersheds in 

order to identify areas with the highest potential to contribute to the viability of the 

surrogate species. The conservation emphasis areas included aquatic and riparian, 

snag and down wood, moist forests, mesic-dry forests, and postfire habitats, human 

access, domestic grazing, and invasive species. The conservation emhpasis areas 

and associated management considerations address many of the climate change 

adaptations identified by Gaines et al. (2012), and could be used to inform forest 

planning through an interdisciplinary planning process to address multiple resource 

objectives. 

Aquatic and Riparian Habitat Conservation Emphasis Area

We identified eight surrogate species whose viability was closely linked to riparian 

habitats. These species represent a wide range of riparian habitats and included 

the water vole, inland tailed frog, bald eagle, MacGillivray’s warbler, Columbia 
236

GENERAL TECHNICAL REPORT PNW-GTR-907

spotted frog, Wilson’s snipe, eared grebe, and marsh wren. Other surrogate species 

whose viability would also benefit from management considerations include the 

northern bog lemming, American marten, fringed myotis, peregrine falcon, tiger salamander, northern harrier, Townsend’s big-eared bat, wood duck, and harlequin duck.

The following management considerations address issues we identified regarding the viability of the surrogate species associated with riparian and wetland 

habitats. The number of watersheds that are priority are shown in table 48.

1. Viability outcomes could be improved by riparian management that considers the needs of fish and wildlife resources and address the effects of roads, 

campgrounds, grazing, and vegetation management. Riparian management zones could be designated to (a) protect habitat adjacent to streams, 

wetlands, ponds and lakes; and (b) facilitate the movement/dispersal of 

wildlife. 

2. Restoration of riparian habitats by reducing the negative effects of roads on 

source habitats within priority watersheds (table 48).

3. Restoration of wetland and wet meadow habitats by reducing the impacts of 

water-based recreation, invasive species, and conifer encroachment within 

priority watersheds (table 48).

Snag and Down Wood Conservation Emphasis Area

We reviewed DecAID (Mellen-McLean et al. 2009) to develop reference conditions 

for snag density distributions (tables 49 and 50) that can be used to develop management considerations for snag and downed wood habitats. We developed estimates 

(histograms) of the reference conditions using the inventory data for unharvested 

plots (including plots with no measurable snags) for the structural stages (weighted 

averages) within the mesic, cold-moist, and cold-dry forest types. For the dry forest, 

we used reference condition estimates from Harrod et al. (1998). 

Forested Habitats Conservation Emphasis Areas

The conservation emphasis areas for forest habitats include three parts: moist 

forests, mesic and dry forests, and postfire forests. 

Moist forests conservation emphasis area— 

We used habitat condition information from three surrogate species associated with 

moist late-successional forests to identify multispecies management considerations: 

northern goshawk, pileated woodpecker, and American marten. Other surrogate 

species whose viability is likely influenced by these measures include the Canada 
237

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Table 48—Priority watersheds by habitat condition, conservation approach, and conservation emphasis

Number of priority watersheds 

by habitat condition and conservation emphasis

Habitat condition Potential management options to consider

Aquatic and riparianMoist forest habitatMesic-dry forest Postfire habitatHuman access Domestic grazingInvasive species

Habitat condition 1 Protection of existing source habitat is a high priority. 

Restoration to enhance source habitat amount and connectivity would occur as needed. 

7 12 22 20 13 11 6

Habitat condition 2 Restoration to enhance source habitat amount and connectivity is a high priority. Protection of existing source 

habitat is also a priority. 

41 19 21 31 45 31 37

Habitat condition 3 A combination of protection and restoration would occur 

in these watersheds. Restoration would depend on the 

availability of resources after higher priority (habitat 

condition 1, 2) watersheds have been restored.

5 26 17 12 1 9 12

Habitat condition 4 The primary emphasis in these watersheds is providing suitable conditions for species dispersal in order to 

enhance habitat connectivity.

3 7 3 0 5 5 0

Habitat condition 5 The limited amount of source habitat that is in federal 

ownership limits the contribution of these watersheds 

to species sustainability. However, depending on their 

juxtaposition to other watersheds, protecting or restoring 

source habitat conditions may still be important.

16 10 9 8 13 16 16

Table 49—Snag reference conditions by density distribution 

classes for small and large snag sizes for dry forests (applied 

at the watershed scale)

Snag size class

Percent of landscape in snag density classes 

(number/acre)

0-4 4-12 12-20 20-28 >28

>10 in d.b.h. 82.2 13.7 2.1 1.4 0.4

0-2 2-6 6-10 10-14 >14

>20 in d.b.h. 89.0 9.6 0.6 0.0 0.0

D.B.H. = diameter at breast height.
238

GENERAL TECHNICAL REPORT PNW-GTR-907

lynx, Cassin’s finch, larch mountain salamander, tailed frog, harlequin duck, 

fringed myotis, and the bald eagle. 

The following management considerations may be used to enhance the viability 

of the surrogate species associated with moist forests:

1. In moist forests within watersheds with habitat condition 1a and 1b protection or restoration of late-successional forest habitat conditions (Franklin and 

Johnson 2012), can enhance forest species viability. Reference conditions can 

be used as a guide to determine sustainable levels of late-successional forest 

within each subbasin or watershed (Agee 2003, Hessburg et al. 2000, 2013; 

USFWS 2011; Wimberly et al. 2000). In areas where the management goal is 

to restore large tree structures, treatments may include thinning young stands 

that were previously harvested to accelerate the development of old-forest 

structures and restore patch sizes (Franklin and Johnson 2012).

2. Patch-size distribution measured at the watershed scale could be managed 

within or toward reference conditions (Hessburg et al. 1999a, Perry et al. 

2011).

3. To increase viability outcomes, managers could identify and protect large 

tree and snag habitat (see snag and down wood strategy) within all forest 

types, including postfire habitats (Franklin and Johnson 2012). These structures are important for both current and future (legacy structure) habitat for 

late-successional species.

4. Viability outcomes for goshawk could be improved by maintaining stands 

with active goshawk nests in old-forest conditions (Wisdom et al. 2000). 

The Northern Goshawk Scientific Committee recommends three 30-ac 

nest stands per breeding pair and three additional 30-ac replacement stands 

within a 6,000-ac area that functions as potential home range (Reynolds et 

al. 1992). 

Table 50—Snag reference conditions by density distribution classes for

small and large snag sizes for mesic forests (applied at the watershed scale) 

Snag size class Percentage of landscape in snag density classes (number/acre)

0–6 6–18 18–30 30–42 >42

>10 in d.b.h. 70.0 18.0 4.7 4.1 2.8

0–2 2–6 6–10 10–14 >14

>20 in d.b.h. 77.9 12.0 6.0 2.6 1.6

D.B.H. = diameter at breast height.

Managers could 

identify and protect 

large tree and snag 

habitat (see snag and 

down wood strategy) 

within all forest types, 

including postfire 

habitats. 
239

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

5. The northern spotted owl could be a high priority for monitoring within its 

range on the Okanogan-Wenatchee National Forest because of its negative 

trend in habitat loss owing to fire (Davis and Lint 2005, Davis et al. 2011), 

negative population trends (Anthony et al. 2006, Forsman et al. 2010), and 

competition from barred owls (Singleton et al. 2010).

Mesic and dry forests conservation emphasis area— 

We used habitat condition information from two surrogate species associated with 

large-tree structures within mesic and dry forests to identify multispecies management considerations: northern goshawk and white-headed woodpecker. Other surrogate species whose viability is likely influenced include Cassin’s finch, pileated 

woodpecker, western bluebird, western gray squirrel, Lewis’s woodpecker, golden 

eagle, bighorn sheep, and bald eagle. 

The following management considerations may be used to enhance the viability 

of the surrogate species associated with mesic and dry forests. The number of 

watersheds that are priority management considerations are shown in table 48.

1. Protection of existing old-forest ponderosa pine habitats would enhance viability outcomes (Franklin and Johnson 2012). These forests provide important source habitat for surrogate species associated with dry forests and are 

currently available at levels well below reference conditions (Hessburg et al. 

1999a).

2. In mesic and dry forests, restoration of structure, composition, and function 

using a combination of thinning or prescribed fire (Agee 2003, Gaines et al. 

2007, Harrod et al. 2007) could improve habitats. Reference conditions may 

be used to guide the development of stand- (Churchill et al. 2013, Harrod et 

al. 1999, Franklin et al. 2008) and landscape-level desired conditions (Agee 

2003; Hessburg et al. 2000, 2005, 2007, 2013).

3. Patch-size distribution measured at the watershed scale could be managed 

within or toward reference conditions (Hessburg et al. 2007, Perry et al. 2011).

4. Protection of active goshawk nests in old-forest conditions (Wisdom et al. 

2000) could contribute to their viability. The Northern Goshawk Scientific 

Committee recommends three 30-ac nest stands per breeding pair and three 

additional 30-ac replacement stands within a 6,000-ac area that function as 

potential home range, (Reynolds et al. 1992). This may require predisturbance surveys for goshawks.

In mesic and dry 

forests, restoration of 

structure, composition, 

and function using a 

combination of thinning 

or prescribed fire could 

improve habitats.
240

GENERAL TECHNICAL REPORT PNW-GTR-907

5. Surrogate species associated with mesic and dry forests could be a high priority for monitoring. The white-headed woodpecker and western bluebird 

were ranked as a high priority (see chapter 4) throughout the assessment 

area, owing to the strongly negative trends in source habitat availability 

and the unknown effects of dry forest restoration on their habitat use and 

productivity.

6. Habitat for the northern spotted owl in dry and mesic forests may be 

restored using the upper end of the reference conditions to restore mesic and 

dry forest processes, patterns, and functions (Courtney et al. 2008, Franklin 

et al. 2008, Gaines et al. 2010b, Hessburg et al. 2013, USFWS 2011). The 

risk of loss of spotted owl habitat to uncharacteristically high-severity fire 

may be reduced by strategically locating restoration treatments to reduce 

landscape fire movement (Agar et al. 2007, Franklin et al. 2008, Gaines et 

al. 2010b, Lehmkuhl et al. 2007b, USFWS 2011). Where treatments occur, 

stand conditions favorable for white-headed woodpeckers and other dry forest-associated surrogate species may be created (Gaines et al. 2007, 2010a). 

Postfire habitat conservation emphasis area— 

The primary surrogate species we used to develop the multispecies management 

considerations for postfire habitats were the Lewis’s woodpecker and black-backed 

woodpecker. Additional surrogate species that we expect to benefit include Canada 

lynx, white-headed woodpecker, western bluebird, and fringed myotis.

The following management considerations may be used to enhance the viability 

of the surrogate species associated with postfire habitats. The number of watersheds 

that are priority for management considerations are shown in table 48.

1. Reference conditions measured at the landscape scale could be used to 

evaluate if habitat components are distributed across the landscape in a sustainable fashion (Agee 2000, Hessburg et al. 2007). Increase opportunities 

to allow wildfire to burn or ignite fires when conditions and opportunities 

exist within priority watersheds (table 48). 

2. Watersheds in habitat conditions 1a and 1b for black-backed and Lewis’s woodpeckers could be managed for postfire habitats using reference conditions. 

Postfire timber harvest could be designed to meet habitat needs for the Lewis’s 

woodpecker (see chapter 2) and evaluated using the Lewis’s woodpecker surrogate species assessment model at the watershed and subbasin scales. 

3. In watersheds with habitat condition 2 and 3, planned and unplanned ignitions may be used to restore the availability of postfire habitats toward 

reference conditions. 
241

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Human Access Emphasis Area

We used habitat condition information from the Canada lynx, wolverine, bighorn 

sheep, and harlequin duck to conduct a multispecies assessment that addresses 

habitat and human-disturbance related risk factors. Other surrogate species whose 

viability is likely influenced include the golden eagle, sage thrasher, eared grebe, 

northern bog lemming, northern goshawk, American marten, white-headed woodpecker, western bluebird, fringed myotis, western gray squirrel, Lewis’s woodpecker, black-backed woodpecker, peregrine falcon, tiger salamander, northern 

harrier, Townsend’s big-eared bat, and the wood duck. 

The following management considerations may be used to enhance the viability 

of the surrogate species whose source habitats are influenced by roads and trails. 

The number of watersheds that are priority management considerations are shown 

in table 48.

1. Winter recreation could be managed using the lynx consideration assessment and strategy guidance for snow compacting activities (Ruediger et al. 

2000, ILBT 2013), especially in watersheds identified as habitat condition 

1 and 2 (table 48) within the areas identified as core and secondary for the 

Canada lynx (USFWS 2005, ILBT 2013). A more complete inventory of the 

existing locations of snowmobile use and other compacted winter routes 

would aid in the development of a winter recreation strategy.

2. The impacts of human activities (roads, trails, dispersed recreation sites, 

etc.) on riparian habitats could be reduced by emphasizing watersheds in 

habitat conditions 1 and 2. 

3. The impacts of roads on surrogate species source habitats could be reduced 

by considering road management that limits overall road density and the 

amount of area within a zone of influence of a road (Gaines et al. 2003). The 

number of priority watersheds for addressing road-related effects are identified in table 48. In many cases, these watersheds overlap with grizzly bear 

recovery areas where access management guidelines will be implemented 

(USFWS 1997b), providing conservation values for multiple species.

4. Using Singleton et al. (2002), WHCWG (2010), and permeability information from this assessment, unroaded areas or areas with low road densities 

could be identified to serve as steppingstones to enhance habitat permeability for wildlife, especially within watersheds identified as important for 

connectivity (Habitat condition 4, table 48). Road crossing structures could 

facilitate movement across the Interstate 90 corridor, or other similar areas. 

Human activities adjacent to highways could be managed so that wildlife 

could access crossing structures.

The impacts of roads 

on surrogate species 

source habitats 

could be reduced 

by considering road 

management that limits 

overall road density 

and the amount of 

area within a zone of 

influence of a road.
242

GENERAL TECHNICAL REPORT PNW-GTR-907

Domestic Grazing Emphasis Area

The primary surrogate species we used in our multispecies conservation assessment 

to address issues associated with domestic grazing were the golden eagle, bighorn 

sheep, northern harrier, and the MacGillivray’s warbler. Additional surrogate 

species that we expect to benefit include the water vole, western gray squirrel, 

northern bog lemming, Cassin’s finch, fox sparrow, lark sparrow, sage thrasher, 

tiger salamander, and the Columbia spotted frog. Lehmkuhl et al. (2013) provide a 

comprehensive assessment of grazing impacts from domestic and wild ungulates on 

the southern portion of the Okanogan-Wenatchee National Forest.

The following management considerations may be used to enhance the viability 

of the surrogate species whose source habitats are influenced by domestic grazing. 

The number of watersheds that are priority are shown in table 48.

1. Grazing management could be developed to (a) restore habitat conditions in 

riparian and other unique habitats (Beebe et al. 2002, Lehmkuhl et al. 2013); 

(b) provide forage for ungulates on winter ranges (Lehmkuhl et al. 2013); 

and foraging habitat for species such as the golden eagle; and (c) maintain known populations of the mardon skipper (U.S. Forest Service Pacific 

Northwest Region [6] sensitive species).

2. Reducing the potential for disease spread from domestic to bighorn 

sheep in areas where bighorn sheep are currently present (Schommer and 

Woolever 2008) would increase the likelihood of persistence.

Invasive Species Emphasis Area

The surrogate species we used to assess impacts from invasive species were the 

golden eagle, tiger salamander, Columbia spotted frog, eared grebe, and marsh 

wren. Additional surrogate species that we expect to benefit include sage thrasher, 

tailed frog, and the MacGillivray’s warbler.

The following management considerations may be used to enhance the viability 

of the surrogate species whose source habitats are influenced by invasive species. 

The number of watersheds that are priority are shown in table 48.

1. Reducing the impact and spread of invasive plant species into grassland, 

shrubland, and wetland habitats that provide source habitat for surrogate 

wildlife species could improve habitat quality.

2. Coordination with the state fisheries agency to reduce the impacts of introduced fish species would increase the likelihood of maintaining viable 

populations.
243

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Chapter 4: Monitoring and Adaptive 

Management

Monitoring and adaptive management become vital tools to help resource managers 

deal with complex management questions and high levels of uncertainty (Busch and 

Trexler 2003, Christensen et al. 1996, Christensen 1997, Everett et al. 1994, Gaines 

et al. 2003b, Suring et al. 2011). Assessing the viability of species is complex and 

involves uncertainties. Key assumptions made in the assessment of species viability 

in our process include (Suring et al. 2011):

• Surrogate species assessment models provide a conceptual outline of the 

primary habitat and risk factors that determine the viability of surrogate 

species.

• The assessment models provide a reasonable and scientifically credible 

structural approximation of the species niche in the ecosystem that can be 

used to identify key monitoring elements.

• Surrogate species represent the species group in a manner that provides 

insights into the capability of the habitat to support other species associated 

with the group. 

These assumptions guide development of specific monitoring and research 

questions that differ for each surrogate species. The sheer number of surrogate 

species selected to represent various habitats and risk factors make it impossible to 

monitor all surrogate species in a rigorous manner owing to cost and impracticality. 

Therefore, we developed a process to prioritize surrogate species monitoring based 

on the following:

• The results of the assessment of surrogate species viability.

• Whether the effects of risk factors that influenced species’ viability are 

likely to increase, decrease, or remain the same based on proposed management options. 

• The degree of uncertainty associated with our ability to predict the relationship 

between surrogate species, their source habitat, and associated risk factors.

We anticipate using the surrogate species assessment models in an adaptive 

management approach where the models provide an initial estimate, based on current science and professional knowledge, of how the surrogate species interacts with 

source habitat and risk factors (Nyberg et al. 2006). The surrogate species assessment models we developed can serve several important purposes in an adaptive 

management process, including documenting the current state of knowledge about 

a species, identifying and clarifying key assumptions, identifying areas of uncertainty, testing sensitivity of outcomes to changes in variable values, and evaluating 

alternative decisions (Nyberg et al. 2006). 

We anticipate using 

the surrogate species 

assessment models 

in an adaptive 

management approach 

where the models 

provide an initial 

estimate, based 

on current science 

and professional 

knowledge, of how 

the surrogate species 

interacts with source 

habitat and risk factors. 
244

GENERAL TECHNICAL REPORT PNW-GTR-907

Bayesian belief and decision networks are modeling techniques that are well 

suited to adaptive management applications (Nyberg et al. 2006). We developed 

a process to determine the priority of a surrogate species for monitoring and a 

recommended intensity of monitoring that are based on the information used in the 

surrogate species assessment models. We based this process largely on the degree 

of risk posed to the surrogate species. 

Surrogate Species Monitoring Priorities Based on Viability 

Outcomes

We used the viability outcomes based on current conditions to develop an initial 

priority rating for each surrogate species for monitoring (table 51); those with low 

viability outcomes were high priority, and those with high viability outcomes were 

low priority (fig. 81). We defined a species that is low priority for monitoring as one 

with a >60 percent probability of outcome B or better and with <5 percent outcome 

E. A high-priority species was defined as one with a >10 percent probability of 

outcome E or >40 percent probability of outcome D. The remainder of the species 

were moderate priority for monitoring.

Based on this approach, monitoring for species ranked as high would include 

monitoring habitat, risk factors, and population trend (fig. 81). For those species 

ranked as moderate, habitat and risk factors would be monitored every 2 years to 

determine trends in their viability outcomes. For species ranked as low, habitat and 

risk factors would be monitored every 5 years.

Table 51—Priority of focal species for monitoring based on current condition 

estimates of their viability outcomes

Monitoring priority Surrogate species

High Cassin’s finch, eared grebe, fox sparrow, lark sparrow, 

sage thrasher, western bluebird, white-headed woodpecker, Wilson’s snipe, bighorn sheep

Moderate Bald eagle, black-backed woodpecker, spotted frog, 

Lewis’s woodpecker, MacGillivray’s warbler, marsh 

wren, northern harrier, pileated woodpecker, tailed frog, 

tiger salamander, wood duck, American marten

Low Golden eagle, harlequin duck, goshawk, peregrine falcon, 

Canada lynx, wolverine
245

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Figure 81—Relationship between focal species monitoring priorities and the viability outcome, predicted risk factors associated with the management option, and the degree of scientific uncertainty.

The final determination about which species are priority to monitor and the 

intensity of the monitoring can be based on how well the management guidance in 

land and resource management plans address habitat and risk factors. The analyses 

of how well habitats and risk factors are addressed in management guidance could 

be displayed in the effects analyses for each of the management alternatives considered (e.g., see Lehmkuhl et al. 1997, Raphael et al. 2001). 

Metric Equivalents

When you now: Multiply by: To find:

Inches (in) 2.54 Centimeters

Feet (ft) .305 Meters

Miles (mi) 1.609 Kilometers

Acres (ac) .405 Hectares
246

GENERAL TECHNICAL REPORT PNW-GTR-907

Literature Cited 

Abele, S.C.; Saab, V.A.; Garton, E.O. 2004. Lewis’s woodpecker (melanerpes 

lewis): a technical conservation assessment. USDA Forest Service, Rocky 

Mountain Region. http://www.fs.fed.us/r2/projects/scp/assessments/

lewisswoodpecker.pdf. (May 2010).

Abuladze, A.; Shergalin, J. 2002. The golden eagle in north Caucasia and 

Transcaucasia. Journal of Raptor Research. 36 (supplement): 10–17.

Adams, M.J.; Pearl, C.A.; McCreary, B.; Galvan, S.K.; Wessell, S.; Wente, W. 

H.; Anderson, C.W.; Kuehl, A.B. 2009. Short-term effect of cattle exclosures 

on Columbia spotted frog populations and habitat in northeastern Oregon. 

Journal of Herpetology. 43: 132–138.

Agee, J.K. 2000. Disturbance ecology of North American boreal forests and 

associated northern mixed/subalpine forests. In: Ruggerio, L.F.; Aubry, K.B.; 

Buskirk, S.W.; Koehler, G.M.; Krebs, C.J.; McKelvey, K.S.; Squires, J.R. Ecology 

and conservation of lynx in the United States. Gen. Tech. Rep. RMRS-GTR30WWW. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Research Station: 39–82. 

Agee, J.K. 2003. Historical range of variability in eastern Cascade forests, 

Washington, USA. Landscape Ecology. 18: 725–740.

Ager, A.A.; Finney, M.A.; Kerns, B.K.; Maffei, H. 2007. Modeling wildfire risk 

to northern spotted owl (Strix occidentalis caurina) habitat in central Oregon, 

USA. Forest Ecology and Management. 246: 45–56.

Alexander, S.M.; Waters, N.M. 2000. Modeling wildlife movement requisites 

in the Banff-Bow Valley transportation corridor. International conference on 

integrating GIS and environmental modeling (GIS/EM4). http://www.colorado.

edu/research/cires/banff/pubpapers/24/. (December 7, 2014)

Altman, B. 2000a. Conservation strategy for landbirds in the Northern Rocky 

Mountains of eastern Oregon and Washington Oregon—Washington Partners 

in Flight. Version 1. 140 p. http://www.orwapif.org/pdf/northern_rockies.pdf. 

1/15/08.

Altman, B. 2000b. Conservation strategy for landbirds of the east-slope of 

the Cascade Mountains in Oregon and Washington. Version 1.0. June 2000. 

American Bird Conservancy and Oregon-Washington Partners in Flight. 

http://www.orwapif.org/sites/default/files/east_slope.pdf. (May 2, 2014).
247

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Andelman, S.J.; Beissinger, S.; Cochrane, J.F.; Gerber, L.; GomezPriego, P.; Groves, C.; Haufler, J.; Holthausen, R.; Lee, D.; Maguire, L.; 

Noon, B.; Ralls, K.; Regan, H. 2001. Scientific standards for conducting 

viability assessments under the National Forest Management Act: report and 

recommendations of the NCEAS working group. National Center for Ecological 

Analysis and Synthesis, University of California, USA. http//www.fs.fed.us/psw/

rsl/projects/wild/lee/lee3.pdf. (24 January 2017).

Andelman, S.J.; Groves, C.; Regan, H.M. 2004. A review of protocols 

for selecting species at risk in the context of U.S. Forest Service viability 

assessments. Acta Oecologia. 26: 75–83.

Andersen, D.E. 1991. Management of North American grasslands for raptors. 

In: Pendleton, B.G.; Krahe, M.N.; LeFranc, K., Jr.; Titus, K.; Bednarz, J.C.; 

Anderson, D.E.; Millsap, B.A., eds. Proceedings of the Midwest raptor 

management symposium and workshop. Washington, DC: National Wildlife 

Federation: 203–210. 

Anderson, E.M. 2007. Changes in bird communities and willow habitats 

associated with fed elk. Wilson Journal of Ornithology. 119: 400–409.

Anderson, M. 1995. Interactions between Lythrum salicaria and native organisms: 

a critical review. Environmental Management. 19: 22–231.

Andruskiw, M.; Fryxell, J.M.; Thompson, I.D.; Baker, J.A. 2008. Habitatmediated variation in predation risk by the American marten. Ecology. 89: 

2273–2280.

Anthony, R.G.; Forsman, E.D.; Franklin, A.B.; Anderson, D.R.; Burnham, 

K.P.; White, G.C.; Schwarz, C.J.; Nichols, J.D.; Hines, J.E.; Olson, G.S.; 

Ackers, S.H.; Andrews, L.S.; Biswell, B.L.; Carlson, P.C.; Diller, L.V.; 

Dugger, K.M.; Fehring, K.E.; Fleming, T.L.; Gerhardt, R.P.; Gremel, 

S.A.; Gutierrez, R.J.; Happe, P.J.; Herter, D.R.; Higley, J.M.; Horn, R.B.; 

Irwin, L.L.; Loschl, P.J.; Reid, J.A.; Sovern, S.G. 2006. Status and trends in 

demography of northern spotted owls, 1983-2003. Wildlife Monographs. 163: 

1–48.

Anthony, R.G.; Isaacs, F.B. 1989. Characteristics of bald eagle nest sites in 

Oregon. Journal of Wildlife Management. 53: 148–159.
248

GENERAL TECHNICAL REPORT PNW-GTR-907

Anthony, R.G.; O’Connell, W.A.; Pollock, M.M.; Hallett, J.G. 2003. Association 

of mammals with riparian ecosystems in Pacific Northwest forests. In: Zabel, 

C.J.; Anthony, R.G., eds. Mammal community dynamics: management and 

conservation in the coniferous forests of North America. New York: Cambridge 

University Press: 510–563.

Anthony, R.G.; Steidl, R.J.; McGarigal, K. 1995. Recreation and bald eagles 

in the Pacific Northwest. In: Knight, R.L.; Gutzwiller, K.J., eds. Wildlife and 

recreationists: coexistence through management and research. Washington, DC: 

Island Press: 223–241.

Apfelbaum, S.I.; Seelbach, P. 1983. Nest tree, habitat selection and productivity of 

seven North American raptor species based on the Cornell University nest record 

card program. Raptor Research. 17: 97–113.

Ashley, E.P.; Robinson, J.T. 1996. Road mortality of amphibians, reptiles, and 

other wildlife on the Long Point Causeway, Lake Erie, Ontario. Canadian FieldNaturalist. 110(3): 403–412.

Ashley, J. 1994. 1992-93. Harlequin duck monitoring and inventory in Glacier 

National Park, Montana. Glacier National Park, MT: U.S. Department of the 

Interior, National Park Service, Glacier National Park, Division of Resource 

Management, Montana. 57 p.

Aubry, K.B. 2000. Amphibians in managed, second-growth Douglas-fir forests. 

Journal of Wildlife Management. 64(4): 1041–1052.

Aubry, K.B.; Koehler, G.; Squires, J.R. 1999. Ecology of Canada lynx in the 

southern boreal forests. In: Ruggerio, L.F.; Aubry, K.B.; Buskirk, S.W.; Koehler, 

G.M.; Krebs, C.J.; McKelvey, K.S.; Squires, J.R. Ecology and conservation of 

lynx in the United States. Gen. Tech. Rep. RMRS-GTR-30WWW. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station: 373–396.

Aubry, K.B.; McKelvey, K.S.; Copeland, J.P. 2007. Distribution and broadscale 

habitat relations of the wolverine in the contiguous United States. Journal of 

Wildlife Management. 71(7): 2147–2159.

Austin, K. 1993. Habitat use and home range size of breeding northern goshawks in 

the southern Cascades. Corvallis, OR: Oregon State University. 57 p. M.S. thesis.

Baglien, J.W. 1975. Biology and habitat requirements of the nesting golden eagle 

in southwestern Montana. Bozeman, MT: Montana State University. 53 p. M.S. 

thesis.
249

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Baker, M.D.; Lacki, M.L. 2006. Day-roosting habitat of female long legged myotis 

in ponderosa pine forests. Journal of Wildlife Management. 70: 207–215.

Baldwin, R.A.; Bender, L.C. 2008. Distribution, occupancy, and habitat correlates 

of American martens (Martes americana) in Rocky Mountain National Park, 

Colorado. Journal of Mammalogy. 89: 419–427.

Banci, V. 1994. Wolverine. In: Ruggiero, L.R.; Aubry, K.B.; Buskirk, S.W.; Lyon 

L.J.; Zielinski, W.J., eds. The scientific basis for conserving forest carnivores: 

American marten, fisher, lynx and wolverine in the Western United States. Gen. 

Tech. Rep. RM-GTR-254. Fort Collins, CO: U.S. Department of Agriculture, 

Forest Service, Rocky Mountain Forest and Range Experiment Station: 99–127. 

Chapter 5.

Banks, R. 1970. The fox sparrow on the west slope of the Oregon Cascades. 

Condor. 72: 369–370.

Banner, A.; Schaller, S. 2001. Gulf of Maine watershed habitat analysis. Falmouth, 

ME: U.S. Fish and Wildlife Service, Gulf of Maine Coastal Program. 160 p.

Barnum, D.A. 1975. Aspects of western gray squirrel ecology. Pullman, WA: 

Washington State University. 55 p. M.S. thesis. 

Bate, L.J.; Wisdom, M.J.; Wales, B.C. 2007. Snag densities in relation to human 

access and associated management factors in forests of Northeastern Oregon, 

USA. Landscape and Urban Planning. 80: 278–291.

Bates, J.W.; Moretti, M.O. 1994. Golden eagle (Aquila chrysaetos) population 

ecology in eastern Utah. Great Basin Naturalist. 54: 248–255.

Baydeck, R.K.; Campa, H., III; Haufler, J.B. 1999. Practical approaches to the 

conservation of biological diversity. Covelo, CA: Island Press. 327 p.

Beebe, J.; Everett, R.; Scherer, G.; Davis, C. 2002. Effect of fertilizer 

applications and grazing exclusion on species composition and biomass in wet 

meadow restoration in eastern Washington. Res. Pap. PNW-RP-542. Portland, 

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 15 p.

Beecham, J.J., Jr. 1970. Nesting ecology of the golden eagle in southwestern 

Idaho. Moscow, ID: University of Idaho. 48 p. M.S. thesis. 

Beecham, J.J.; Kochert, M.N. 1975. Breeding biology of the golden eagle in 

southwestern Idaho. Wilson Bulletin. 87: 506–513.
250

GENERAL TECHNICAL REPORT PNW-GTR-907

Begley, J. 2007. Modeling Swakane bighorn sheep habitat and dispersal. 

Ellensburg, WA: Central Washington University. 117 p. M.S. thesis. 

Beier, P.; Drennen, J.E. 1997. Forest structure and prey abundance in foraging 

areas of northern goshawks. Ecological Applications. 7(2): 564–571.

Bengston, S. 1972. Breeding ecology of the harlequin duck, Histrionicus 

histrionicus, in Iceland. Ornis Scandinavica. 3: 1–19.

Bengston, S.; Ulfstrand, S. 1971. Food resources and breeding frequency of 

the harlequin duck Histrionicus histrionicus in Iceland. Oikos. 22: 235–239.

Benoit, L.K.; Askins, R.A. 2002. Relationship between habitat area and the 

distribution of tidal marsh birds. Wilson Bulletin. 114: 314–323.

Bent, A.C. 1961. Life histories of North American birds of prey. Part 1. 

New York, NY: Dover Publications Inc. 409 p.

Berger, J.; Stacey, P.B.; Bellis, L.B.; Johnson, M.P. 2001. A mammalian 

predator-prey imbalance: grizzly bear and wolf extinction affect avian 

neotropical migrants. Ecological Applications. 11: 947–960.

Berkey, G.; Crawford, R.; Galipeau, S.; Johnson, D.; Lambeth, D.; Kreil, R. 

1993. A review of wildlife management practices in North Dakota: effects on 

nongame bird populations and habitats. Report submitted to Region 6. Denver, 

CO: U.S. Fish and Wildlife Service. 51 p.

Bestelmeyer, B.T. 2006. Threshold concepts and their use in rangeland 

management and restoration: the good, the bad and the insidious. Restoration 

Ecology. 14(3): 325–329.

Bettinger, K.A. 2003. Cassin’s finch. In: Marshall, D.B.; Hunter, M.G.; Contreras, 

A.L., eds. Birds of Oregon: a general reference. Corvallis, OR: Oregon State 

University Press: 599–601.

Biek, R.; Mills, L.S.; Bury, R.B. 2002. Terrestrial and stream amphibians across 

clear-cut interfaces in the Siskiyou Mountains, Oregon. Northwest Science. 

76(2): 129–139.

Bildstein, K.L.; Gollop, J.B. 1988. Northern harrier. In: Palmer, R.S., ed. 

Handbook of North American birds: vol. 4. Diurnal raptors. New Haven, CN: 

Yale University Pres: 251–303.

Bittner, S.L.; Rongstad, O.J. 1982. Snowshoe hare and allies. In: Chapman, J.A.; 

Feldhamer, G.A. eds. Wild mammals of North America. Baltimore, MD: John 

Hopkins University Press: 146–163. 
251

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Black, H.L. 1974. A north temperate bat community: structure and prey 

populations. Journal of Mammalogy. 55: 138–157.

Blakesley, J.A.; Reese, K.P. 1988. Avian use of campground and non-campground 

sites in riparian zones. Journal of Wildlife Management. 52: 399–402.

Block, W.M.; Brennan, L.A. 1987. Characteristics of Lewis’s woodpecker on the 

Modoc Plateau, California. Western Birds. 18: 209–212.

Blossey, B.; Skinner, L.C.; Taylor, J. 2001. Impact and management of purple 

loosestrife (Lythrum salicaria) in North America. Biodiversity and Conservation. 

10: 1787–1807.

Bock, C.E. 1970. The ecology and behavior of the Lewis’s woodpecker 

(Asyndesmus lewis). University of California Publications in Zoology. 92: 1–100.

Bock, C.E.; Bock, J.H. 1988. Grassland birds in southeastern Arizona: impacts of 

fire, grazing, and alien vegetation. In: Goriup, P.D., ed. Ecology and conservation 

of grassland birds. International Council for Bird Preservation Publication. 7: 

43–58.

Bock, C.E.; Bock, J.H.; Bennett, B.C. 1995. The avifauna of remnant tallgrass 

prairie near Boulder, Colorado. Prairie Naturalist. 27: 147–157.

Bock, C.E.; Bock, J.H.; Bennett, B.C. 1999. Songbird abundance in grasslands 

at a suburban interface on the Colorado High Plains. In: Vickery, P.D.; 

Herkert, J.R., eds. Ecology and conservation of grassland birds of the Western 

Hemisphere. Studies in Avian Biology. 19: 131–136.

Bock, C.E.; Bock, J.H.; Kenney, W.R.; Hawthorne, V.M. 1984. Responses of 

birds, rodents, and vegetation to livestock exclosure in a semidesert grassland 

site. Journal of Range Management. 37: 239–242.

Bock, C.E.; Saab, V.A.; Rich, T.D.; Dobkin, D.S. 1993. Effects of livestock 

grazing on Neotropical migratory landbirds in western North America. In: 

Finch, D.M.; Stangel, P.W., eds. Status and management of Neotropical migratory 

birds. Gen. Tech. Rep. RM-GTR-229. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Forest and Range Experiment Station: 296–309.

Bock, C.E.; Webb, B. 1984. Birds as grazing indicator species in southeastern 

Arizona. Journal of Wildlife Management. 48: 1045–1049.

Boe, J.S. 1992. Wetland selection by eared grebes, Podiceps nigricollis, in 

Minnesota. Canadian Field-Naturalist. 106: 480–488.
252

GENERAL TECHNICAL REPORT PNW-GTR-907

Boe, J.S. 1993. Colony site selection by eared grebes in Minnesota. Colonial 

Waterbirds. 16: 28–38.

Boeker, E.L. 1974. Status of golden eagle surveys in the Western States. Wildlife 

Society Bulletin. 2: 46–49.

Boeker, E.L.; Ray, T.D. 1971. Golden eagle population studies in the Southwest. 

Condor. 73: 463–467.

Bolger, D.; Scott, T.; Rotenberry, J. 1997. Breeding bird abundance in an 

urbanizing landscape in coastal southern California. Conservation Biology. 

11: 406–421.

Bolger, D.T. 2002. Habitat fragmentation effects on birds in southern California: 

contrast to the “top-down” paradigm. Studies in Avian Biology. 25: 141–157.

Bonar, R.L. 1999. Availability of pileated woodpecker cavities and use by other 

species. Journal of Wildlife Management. 64(1): 52–59.

Bonar, S.A.; Bolding, B.; Divens, M. 2002. Effects of triploid grass carp on 

aquatic plants, water quality, and public satisfaction in Washington state. North 

American Journal of Fisheries Management. 22: 96–105.

Bosch, J.; Rincón, P.A.; Boyero, L.; Martínez-Solano, I. 2006. Effects of 

introduced salmonids on a montane population of Iberian frogs. Conservation 

Biology. 20: 180–189.

Bowles, J.H. 1921. Notes on the California gray squirrel (Sciurus griseus griseus) 

in Pierce County, Washington. Murrelet. 2: 12–13.

Bradford, D.F.; Franson, S.E.; Neale, A.C.; Heggem, D.T.; Miller, G.R.; 

Canterbury, G.E. 1998. Bird species assemblages as indicators of biological 

integrity in Great Basin rangeland. Environmental Monitoring and Assessment. 

49: 1–22.

Braun, C.E.; Baker, M.F.; Eng, R.L.; Gashwiler, J.S.; Schroeder, M.H. 1976. 

Conservation committee report on effects of alteration of sagebrush communities 

on the associated avifauna. Wilson Bulletin. 88: 165–171.

Breininger, D.R.; Barkaszi, M.J.; Smith, R.B.; Oddy, D.M.; Provancha, J.A. 

1998. Prioritizing wildlife taxa for biological diversity conservation at the local 

scale. Environmental Management. 22: 315–321.
253

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Brendel, U.M.; Eberhardt, R.; Wiesmann, K. 2002. Conservation of the 

golden eagle (Aquila chrysaetos) in the European alps—a combination of 

education, cooperation, and modern techniques. Journal of Raptor Research. 

36(supplement): 20–24.

Bright-Smith, D.J.; Mannan, R.W. 1994. Home range and habitat characteristics 

of male northern goshawks. Studies in Avian Biology. 16: 58–65.

Brinson, M.M.; Swift, B.L.; Plantico, R.C.; Barclay, J.S. 1981. Riparian 

ecosystems: their ecology and status. Rep. FWS/OBS-81/17. Kearneysville, WV: 

U.S. Department of the Interior, Fish and Wildlife Service, Biological Service 

Program. 155 p.

Broders, H.G. 2003. Another quantitative measure of bat species activity and 

sampling intensity considerations for the design of ultrasonic monitoring studies. 

Acta Chiroptera. 5: 235–241.

Broders, H.G.; Forbes, G.J. 2004. Interspecific and intersexual variation in roostsite-selection of northern long-eared and little brown bats in the Greater Fundy 

National Park Ecosystem. Journal of Wildlife Management. 68: 602–610.

Brooks, M.L. 1999. Alien annual grasses and fire in the Mojave Desert. Madrono. 

46: 13–19.

Broquet, T.; Ray, N.; Petit, E.; Fryxell, J.M.; Burel, F. 2006. Genetic isolation 

by distance and landscape connectivity in the American marten (Martes 

americana). Landscape Ecology. 21: 877–889.

Brown, H.A. 1990. Morphological variation and age-class determination in 

overwintering tadpoles of the tailed frog. Journal of Zoology. 220: 171–184.

Brown, M.; Dinsmore, J.J. 1986. Implications of marsh size and isolation for 

marsh bird management. Journal of Wildlife Management. 50: 392–397.

Bruce, A.M.; Anderson, R.J.; Allen, G.T. 1982. Observations of golden eagles 

nesting in western Washington. Raptor Research. 16: 132–134.

Buehler, D.A.; Mersmann, T.J.; Fraser, J.D.; Seegar, J.K.D. 1991. Non-breeding 

bald eagle communal and solitary roosting behavior and roost habitat on the 

northern Chesapeake Bay. Journal of Wildlife Management. 55: 273–281.

Bull, E.L. 1987. Ecology of pileated woodpecker in northeastern Oregon. Journal 

of Wildlife Management. 51(2): 472–481.

Bull, E.L. 2003a. Diet and prey availability of Columbia spotted frogs in 

northeastern Oregon. Northwest Science. 77: 349–356.
254

GENERAL TECHNICAL REPORT PNW-GTR-907

Bull, E.L. 2003b. Pileated woodpecker. In: Marshall, D.B.; Hunter, M.G.; 

Contreras, A.L., eds. Birds of Oregon: a general reference. Corvallis, OR: 

Oregon State University Press: 372–374.

Bull, E.L. 2005. Ecology of the Columbia spotted frog in northeastern Oregon. 

Gen. Tech. Rep. PNW-GTR-640. Portland, OR: U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Research Station. 46 p.

Bull, E.L.; Carter, B.E. 1996. Tailed frogs: distribution, ecology, and association 

with timber harvest in northeast Oregon. Res. Pap. PNW-RP-497. Portland, OR: 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 46 p.

Bull, E.L.; Clark, A.A.; Shepherd, J.F. 2005. Short-term effects of fuel reduction 

on pileated woodpeckers in northeastern Oregon—a pilot study. Res. Pap. PNWRP-564. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 17 p.

Bull, E.L.; Deal, J.W.; Hohmann, J.E. 2001. Avian and amphibian use of fenced 

and unfenced stock ponds in northeastern Oregon forests. Res. Pap. PNWRP-539. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 9 p.

Bull, E.L.; Hayes, M.P. 2000. Livestock effects on reproduction of the Columbia 

spotted frog. Journal of Range Management. 53: 291–294.

Bull, E.L.; Hayes, M.P. 2001. Post-breeding movements of Columbia spotted frogs 

(Rana luteiventris) in northeastern Oregon. Western North American Naturalist. 

61: 119–123.

Bull, E.L.; Hayes, M.P. 2002. Overwintering of Columbia spotted frogs in 

northeastern Oregon. Northwest Science. 76: 141–147.

Bull, E.L.; Heater, T.W. 2000. Resting and denning sites of American martens in 

northeastern Oregon. Northwest Science. 74: 179–185.

Bull, E.L.; Heater, T.W.; Shepard, J.F. 2005. Habitat selection by the American 

marten in northeastern Oregon. Northwest Science. 79: 37–43.

Bull, E.L.; Holthausen, R.S. 1993. Habitat use and management of pileated 

woodpeckers in northeastern Oregon. Journal of Wildlife Management. 

57: 335–345. 
255

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Bull, E.L.; Holthausen, R.S.; Henjum, M.G. 1992. Roost trees used by pileated 

woodpeckers in northeastern Oregon. Journal of Wildlife Management. 56: 

786–793.

Bull, E.L.; Jackson, J.E. 1995. Pileated woodpecer (Dryocopus pileatus). In: 

Poole, A.; Gill, F., eds. The birds of North America, No. 148. Philadelphia, 

PA: The Academy of Natural Sciences; Washington, DC: The American 

Ornithologists’ Union: 1–24.

Bull, E.L.; Marx, D.B. 2002. Influence of fish and habitat on amphibian 

communities in high-elevation lakes in northeastern Oregon. Northwest Science. 

76: 240–248.

Bull, E.L.; Nielsen-Pincus, N.; Wales, B.C.; Hayes, J.L. 2007. The influence 

of disturbance events on pileated woodpeckers in northeastern Oregon. Forest 

Ecology and Management. 243: 319–329.

Bull, E.L.; Peterson, S.R.; Thomas, J.W. 1986. Resource partitioning among 

woodpeckers in northeastern Oregon. Res. Note PNW-444. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

19 p.

Bull, E.L.; Snider, M. 1993. Master carpenter. Wildbird. 7(2): 41–43.

Bunnell, K.D.; Flinders, J.T.; Wolfe, M.L. 2006. Potential impacts of coyotes and 

snowmobiles on lynx conservation in the intermountain West. Wildlife Society 

Bulletin. 34(3): 828–838.

Busch, D.E.; Trexler, J.C. 2003. Monitoring ecosystems: interdisciplinary 

approaches for evaluating ecoregional initiatives. Washington, DC: Island Press. 

7(2): 1. http://www.consecol.org/vol7/iss2/art1/. (May 5, 2014).

Bury, R.B. 1983. Differences in amphibian populations in logged and old-growth 

redwood forest. Northwest Science. 57: 167–178.

Bury, R.B. 1994. Vertebrates in the Pacific Northwest: species richness, endemism 

and dependency on old-growth forests. In: Majumdar, S.K.; Brenner, F.J.; 

Lovich, J.E.; Schalles, J.F.; Miller, E.W., eds. Biological diversity: problems and 

challenges. Philidelphia, PA: Pennsylvania Academy of Sciences: 392–404.

Bury, R.B.; Corn, P.S. 1988. Responses of aquatic and streamside amphibians to 

timber harvest: a review. In: Raedeke, K.J., ed. Streamside management: riparian 

wildlife and forestry interactions. Seattle, WA: University of Washington, 

Institute of Forest Resources, Contribution. 59: 165–181.
256

GENERAL TECHNICAL REPORT PNW-GTR-907

Buskirk, S.W.; Forrest, S.C.; Raphael, M.G.; Harlow, H.J. 1989. Winter resting 

site ecology of marten in the central Rocky Mountains. Journal of Wildlife 

Management. 53: 191–196.

Buskirk, S.W.; Ruggiero, L.F.; Krebs, C.J. 1999. Habitat fragmentation and 

interspecific competition: implications for lynx conservation. In: Ruggerio, 

L.F.; Aubry, K.B.; Buskirk, S.W.; Koehler, G.M.; Krebs, C.J.; McKelvey, K.S.; 

Squires, J.R., eds. Ecology and conservation of lynx in the United States. Gen. 

Tech. Rep. RMRS-GTR-30WWW. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research Station: 83–100.

Cahall, R.E.; Hayes, J.P. 2009. Influences of postfire salvage logging on forest 

birds in the eastern Cascades, Oregon, USA. Forest Ecology and Management. 

257: 1119–1128.

Camenzind, F.J. 1969. Nesting ecology and behavior of the golden eagle Aquila 

chrysaetos L. Brigham Young University Science Bulletin. 10: 4–15.

Campbell, N.K.; McTaggart-Cowan, I.; Cooper, J.M.; Kaiser, G.W.; McNall, 

M.C.E. 1990. The birds of British Columbia. Vancouver, BC: University of 

British Columbia Press. 

Campbell, T.M., III. 1979. Short-term effects of timber harvests on pine marten 

ecology. Fort Collins, CO: Colorado State University. 71 p. M.S. thesis. 

Cannings, R.J. 2000. Update COSEWIC status report on sage thrasher 

(Oreoscoptes montanus). Ottawa, ON: Committee on the Status of Endangered 

Wildlife in Canada. 21 p.

Carrete, M.; Sanchez-Zapata, J.A.; Calvo, J.F. 2000. Breeding densities and 

habitat attributes of golden eagles in southeastern Spain. Journal of Raptor 

Research. 34: 48–52.

Carroll, C.; Noss, R.F.; Paquet, P.C. 2001. Carnivores as focal species for 

conservation planning in the Rocky Mountain region. Ecological Applications. 

11(4): 961–980.

Carter, M.F.; Hunter, W.C.; Pashley, D.N.; Rosenberg, K.V. 2000. Setting 

conservation priorities for landbirds in the United States: the Partners in Flight 

approach. Auk. 117(2): 541–548.
257

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Carter, T.C.; Ford, W.M.; Menzel, M.A. 2002. Fire and bats in the southeast 

and mid-Atlantic: more questions than answers? In: Ford, W.M.; Russell, 

K.R.; Moorman, C.E., eds. Proceedings: the role of fire for nongame wildlife 

management and community restoration: traditional uses and new directions. 

Gen. Tech. Rep. NE-288. Newtown Square, PA: U.S. Department of Agriculture, 

Forest Service, Northeastern Research Station: 139–143.

Cassier, E.F.; Groves, C.R. 1989. Breeding ecology of harlequin ducks of the 

Kaniksu National Forest. Boise, ID: Idaho Department of Fish and Game. 

Cassier, E.F.; Schirato, G.; Sharpe, F.; Groves, C.R.; Anderson, R.N. 1993.

Cavity nesting by harlequin ducks in the Pacific Northwest. Wilson Bulletin.

105: 691–694.

Castrale, J.S. 1982. Effects of two sagebrush control methods on non game birds. 

Journal of Wildlife Management. 46: 945–952.

Chambers, C.L.; Holthausen, R.S. 2000. Montane ecosystems used as 

rangelands. In: Jemison, R.; Raish, C., eds. Livestock management in the 

American Southwest: ecology, society, and economics. Amsterdam: Elsevier 

Science: 213–280. 

Chapin, T.G.; Harrison, D.J.; Katnik, D.D. 1998. Influence of landscape pattern 

on habitat use by American marten in an industrial forest. Conservation Biology. 

12: 1327–1337.

Chinnici, S.J.; Bradley, L.C.; Dill, D.R.; Bigger, D. 2007. Using site-specific 

habitat information on young to late-successional avifauna to guide use and 

management of coastal redwood and Douglas-fir forest lands. In: Standiford, 

R.B.; Giusti, G.A.; Valachovic, Y.; Zielinski, W.J.; Furniss, M.J., tech. eds. 

Proceedings of the redwood region forest science symposium: What does the 

future hold? Gen. Tech. Rep. PSW-GTR-194. Albany, CA: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest Research Station: 147–156.

Christensen, N.L. 1997. Implementing ecosystem management: Where do we go 

from here? In: Boyce, M.S.; Haney, A. eds. Ecosystem management: applications 

for sustainable forest and wildlife resources. New Haven, CT: Yale University 

Press: 325–342. 

Christensen, N.L.; Bartuska, A.M.; Brown, J.H.; Carpenter, S.; D’Antonio, 

C.; Francis, R.; Woodmansee, R.G. 1996. The report of the Ecological Society 

of America committee on the scientific basis for ecosystem management. 

Ecological Applications. 6(3): 665–691.
258

GENERAL TECHNICAL REPORT PNW-GTR-907

Churchill, D.J.; Larson, A.J.; Dahlgreen, M.C.; Franklin, J.F.; Hessburg, P.F.; 

Lutz, J.A. 2013. Restoring forest resilience: from reference spatial patterns to 

silvicultural prescriptions and monitoring. Forest Ecology and Management. 

291: 442–457.

Clark, R.J. 1972. Observations of nesting marsh hawks in Manitoba. Blue Jay. 

30: 43–48.

Clarkson, P. 1992. A preliminary investigation into the status and distribution of 

harlequin ducks in Jasper National Park, Alberta, Canada. Jasper National Park, 

Natural Resource Conservation, Alberta.

Clough, G.C.; Albright, J.J. 1987. Occurrence of the northern bog lemming, 

Synapromys borealis, in the northeastern United States. Canadian FieldNaturalist. 101: 611–613.

Collins, J.P.; Jones, T.R.; Berna, H.J. 1988. Conserving genetically distinctive 

populations: the case of the Huachuca tiger salamander. In: Management of 

amphibians, reptiles, and small mammals in North America. Gen. Tech Rep. 

GTR-RM-166. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, 

Rocky Mountain Forest and Range Experiment Station: 45–53.

Collopy, M.W.; Edwards, T.C., Jr. 1989. Territory size, activity budget, and 

role of undulating flight in nesting golden eagles. Journal of Field Ornithology. 

60: 43–51.

Committee of Scientists [COS]. 1999. Saving the people’s land: Stewardship 

into the next century. Washington, DC: U.S. Department of Agriculture, Forest 

Service, Government Printing Office. 

Committee on the Status of Endangered Wildlife in Canada [COSEWIC]. 

2001. COSEWIC assessment and status report on the tiger salamander 

Ambystoma tigrinum in Canada. Prepared by D.M. Schock for COSEWIC, Hull, 

QC. [Place of publication unknown]: [Publisher unknown].

Copeland, J.P. 1996. Biology of the wolverine in central Idaho. Moscow, ID: 

University of Idaho. 138 p. M.S. thesis.

Copeland, J.P.; McKelvey, K.S.; Aubry, K.B.; Landa, A.; Persson, J.; Inman, 

R.M.; Krebs, J.; Lofroth, E.; Golden, H.; Squires, J.R.; Magoun, A.; 

Schwartz, M.K.; Wilmot, J.; Copeland, C.L.; Yates, R.E.; Kojola, I.; May, 

R. 2010. The bioclimatic envelope of the wolverine (Gulo gulo): do climatic 

constraints limit its geographic distribution? Canadian Journal of Zoology. 88: 

233–246.
259

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Copeland, J.P.; Peek, J.M.; Groves, C.R.; Melquist, W.E.; McKelvey, K.S.; 

McDaniel, G.W.; Long, C.D.; Harris, C.E. 2007. Seasonal habitat associations of the wolverine in central Idaho. Journal of Wildlife Management. 71(7): 

2201–2212.

Coppolillo, P.; Gomez, H.; Maisels, F.; Wallace, R. 2008. Selection criteria for 

suites of landscape species as a basis for site-based conservation. Biological 

Conservation. 115: 419–430.

Corn, P.S.; Bury, R.B. 1989. Logging in western Oregon: responses of headwater 

habitats and stream amphibians. Forest Ecology and Management. 29: 39–57.

Corn, P.S.; Jennings, M.L.; Muths, E. 1997. Survey and assessment of amphibian 

populations in Rocky Mountain National Park. Northwestern Naturalist. 78: 

34–55.

Cornish, T.E.; Linders, M.J.; Little, S.E.; Vander Haegen, W.M. 2001.

Notoedric mange in western gray squirrels from Washington. Journal of Wildlife 

Diseases. 37: 630–633.

Coulter, M. 2008. A multi-spatial-scale characterization of lark sparrow habitat 

and the management implications. Bowling Green, OH: Bowling Green State 

University. 63 p. M.S. thesis. 

Courtney, S.P.; Blakesley, J.A.; Bigley, R.E.; Cody, M.L.; Dumbacher, J.P.; 

Fleischer, R.C.; Franklin, A.B.; Franklin, J.F.; Gutierrez, R.J.; Marzluff, 

J.M.; Sztukowski, L. 2004. Scientific evaluation of the status of the Northern 

Spotted Owl. Portland, OR: Sustainable Ecosystems Institute. 357 p.

Cowardin, L.M.; Carter, V.; Golet, F.C.; LaRoe, E.T. 1979. Classification of 

wetlands and deepwater habitats of the United States. Washington, DC: U.S. Fish 

and Wildlife Service, Biological Services Program.

Craig, E.H.; Craig, T.H.; Powers, L.R. 1986. Habitat use by wintering golden 

eagles and rough-legged hawks in southeastern Idaho. Raptor Research. 20: 

69–71.

Crampton, L.H.; Barclay, R.M.R. 1996. Habitat selection by bats in fragmented 

and unfragmented aspen mixedwood stands of different ages. In: Barclay, 

R.M.R.; Brigham, M.R., eds. Bats and forest symposium. Victoria, BC: Research 

Branch, British Columbia Ministry of Forests: 238–259.
260

GENERAL TECHNICAL REPORT PNW-GTR-907

Crisafulli, C.M. 1999. Survey protocol for larch mountain salamander (Plethodon 

larselli). In: Olson, D.H., ed. Survey protocols for amphibians under the Survey 

and Manage provision of the Northwest Forest Plan. Version 3.0. Portland, OR: 

U.S. Department of Agriculture, Forest Service: 253–310. 

Crivelli, A.J. 1983. The destruction of aquatic vegetation by carp: a comparison 

between southern France and the United States. Hydrobiologia. 106: 37–41.

Cuellar, O. 1994. Ecological observation on Rana pretiosa in western Utah. 

Alytes. 12: 109–121.

Cullen, S.A.; Jehl, J.R., Jr.; Nuechterlein, G.L. 1999. Eared grebe (Podiceps 

nigricollis). In: Poole, A.; Gill, F., eds. The Birds of North America, No. 433. 

Philadelphia, PA: The Birds of North America, Inc. 

Cunningham, J.B.; Balda, R.P.; Gaud, W.S. 1980. Selection and use of snags 

by secondary cavity-nesting birds of the ponderosa pine forest. Res. Pap. RM222. Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Forest and Range Experiment Station. 15 p. 

Cushman, S.A. 2006. Effects of habitat loss and fragmentation on amphibians: a 

review and prospectus. Biological Conservation. 128: 231–240.

Cushman, S.A.; McKelvey, K.S.; Flather, C.H.; McGarigal, K. 2007. Do forest 

community types provide a sufficient basis to evaluate biological diversity? 

Frontiers in Ecology and Environment. 6(1): 13–17.

Czech, B.; Krausman, P.R. 1997. Distribution and causation of species 

endangerment in the United States. Science. 277: 1116–1117.

Dahl, T.E. 1990. Wetlands losses in the United States 1780’s to 1980’s. Washington, 

DC: U.S. Fish and Wildlife Service. http://www.npwrc.usgs.gov/resource/

wetlands/wetloss/index.htm. (May 15, 2010). 

Daugherty, C.H.; Sheldon, A.L. 1982. Age-determination, growth, and life 

history of a Montana population of the tailed frog. Herpetologica. 38(4): 

461–468.

Davis, R.; Lint, J. 2005. Habitat status and trend. In: Lint, J. ed. Status and 

trends of northern spotted owl populations and habitat. Gen. Tech. Rep. PNWGTR-648. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station: 21–82.
261

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Davis, R.J.; Dugger, K.M.; Mohoric, S.; Evers, L.; Aney, W.C. 2011. Northwest 

Forest Plan first 15 years (1984–2008):–status and trends of northern spotted

owl populations and habitats. Gen. Tech. Rep. PNW-GTR-850. Portland, OR: U.S 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

147 p.

Daw, S.K.; DeStefano, S. 2001. Forest characteristics of northern goshawk nest 

stands and post-fledgling areas in Oregon. Journal of Wildlife Management.

65: 59–65.

de Jong, J. 1994. Distribution patterns and habitat use by bats in relation to 

landscape heterogeneity, and consequences for conservation. Uppsala, Sweden: 

University of Agricultural Sciences. 132 p. Ph.D. thesis. 

DeMaynadier, P.G.; Hunter, M.L., Jr. 2000. Road effects on amphibian 

movements in a forested landscape. Natural Areas Journal. 20: 56–65.

Denoel, M.; Ficetola, G.F. 2007. Landscape-level thresholds and newt conservation. Ecological Applications. 17(1): 302–309.

Desimone, S.M.; DeStefano, S. 2005. Temporal patterns of northern goshawk nest 

area occupancy and habitat: a retrospective analysis. Journal of Raptor Research. 

39(3): 310–323.

Desimone, S.M.; Hays, D.W. 2003. Northern goshawk. In: Management 

recommendations for Washington’s priority habitats and species. Volume IV: 

Birds. Olympia, WA: Washington Department of Fish and Wildlife: 6–1 to 6–16.

Dixon, R.D. 1995a. Density, nest-site and roost-site characteristics, home-range, 

habitat-use, and behavior of white-headed woodpeckers: Deschutes and Winema 

National Forests, Oregon. Nongame Rep. 93-3-01. Portland, OR: Oregon 

Department of Fish and Wildlife.

Dixon, R.D. 1995b. Ecology of white-headed woodpeckers in the central Oregon 

Cascades. Moscow, ID: University of Idaho, Moscow. 148 p. M.S. thesis. 

Dixon, R.D.; Saab, V.A. 2000. Black-backed woodpecker (Picoides arcticus). In: 

Poole, A.; Gill, F., eds. Birds of North America, No. 509. Philadelphia, PA: The 

Birds of North America, Inc. 20 p.

Dobler, F.C.; Eby, J.; Perry, C.; Richardson, S.; Vander Haegen, M. 1996.

Status of Washington’s shrub-steppe ecosystem: extent, ownership, and wildlife/

vegetation relationships. Olympia, WA: Washington Department of Fish and 

Wildlife. 
262

GENERAL TECHNICAL REPORT PNW-GTR-907

Doubledee, R.A.; Muller, E.B.; Nisbet, R.M. 2003. Bullfrogs, disturbance 

regimes, and the persistence of California red-legged frogs. Journal of Wildlife 

Management. 67: 424–438.

Drennen, J.E.; Beier, P. 2003. Forest structure and prey abundance in winter 

habitat of northern goshawks. Journal of Wildlife Management. 67: 177–185.

Drever, M.C.; Aitken, K.E.H.; Norris, A.R.; Martin, K. 2008. Woodpeckers 

as reliable indicators of bird richness, forest health and harvest. Biological 

Conservation. 141: 624–634.

Duebbert, H.F.; Lokemoen, J.T. 1977. Upland nesting of American bitterns, 

marsh hawks, and short-eared owls. Prairie Naturalist. 9: 33–40.

Dumyahn, J.B.; Zollner, P.A.; Gilbert, J.H. 2007. Winter home-range 

characteristics of American marten in northern Wisconsin. American Midland 

Naturalist. 158: 382–394.

Dunham, J.B.; Pilliod, D.S.; Young, M.K. 2004. Assessing the consequences of 

nonnative trout in headwater ecosystems in western North America. Fisheries. 

29(6): 18–26.

Dupuis, L.A. 1997. Effects of logging on terrestrial amphibians of coastal British 

Columbia. Herpetological Conservation. 1: 185–190.

Dupuis, L.; Bunnell, F.L.; Friele, P.A. 2000. Determinants of the tailed frog’s 

range in British Columbia. Northwest Science. 74: 109–115.

Dupuis, L.; Steventon, D. 1999. Riparian management and the tailed frog in 

northern coastal forests. Forest Ecology and Management. 124: 35–43.

Dvornich, K.M.; McAllister, K.R.; Aubry, K.B. 1997. Amphibians and reptiles 

of Washington state: location data and predicted distributions. Volume 2. 

In: Washington State Gap Analysis–final report. Seattle, WA: Washington 

Cooperative Fish and Wildlife Research Unit, University of Washington. 146 p.

Dwyer, J.K.; Block, W.M. 2000. Effects of wildfire on densities of secondary 

cavity-nesting birds in ponderosa pine forests of northern Arizona. In: Moser, 

W.K.; Moser, C.E., eds. Fire and forest ecology: innovative silviculture and 

vegetation management. Tall Timbers Fire ecology proceedings, No. 21. 

Tallahassee, FL: Tall Timbers Research Station: 151–156.
263

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Eaton, R.L. 1976. Golden eagle (Aquila chrysaetos). In: Brittell, J.D.; Brown, J.M.; 

Eaton, R.L., eds. Marine shoreline fauna of Washington. Volume 2. Washington 

State Department of Game Coastal Zone Environmental Studies Report. 3: 

82–118.

Edelmann, F.; Copeland, J. 1999. Wolverine distribution in the northwestern 

United States and a survey in the Seven Devils Mountains of Idaho. Northwest 

Science. 73: 295–300.

Ellison, L.E.; Everette, A.L.; Bogan, M.A. 2005. Examining patterns of bat 

activity in Bandelier National Monument, New Mexico, by using walking point 

transects. Southwest Naturalist. 50: 197–208.

Erdman, T.C.; Brinker, D.F.; Jacobs, J.P. [and others]. 1998. Productivity, 

population trend, and status of northern goshawks, Accipiter gentilis, in 

northeastern Wisconsin. The Canadian Field Naturalist. 112(1): 17–27.

Evans, D.L. 1982. Status reports on twelve raptors. Special Scientific ReportWildlife No. 238. Washington, DC: U.S. Fish and Wildlife Service. 70 p.

Everett, R.; Hessburg, P.; Jensen, M.; Borman, B. 1994. Eastside forest health 

assessment. Volume 1: Executive summary. Gen. Tech. Rep. PNW-GTR-317. 

[Portland, OR]: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 57 p. 

Everett, R.; Lehmkuhl, J.; Schellhaas, R.; Ohlson, P.; Keenum, D.; Riesterer, 

H.; Spurbeck, D. 1999. Snag dynamics in a chronosequence of 26 wildfires on 

the east slope of the Cascade Range in Washington State, USA. International 

Journal of Wildland Fire. 9(4): 223–234.

Everett, R.L.; Schellhaas, R.; Keenum, D.; Spurbeck, D.; Ohlson, P. 2000. Fire 

history in the ponderosa/Douglas-fir forests on the east slope of the Washington 

Cascades. Forest Ecology and Management. 129: 207–225.

Faaborg, J. 1976. Habitat selection and territorial behavior of the small grebes of 

North Dakota. Wilson Bulletin. 88: 390–399.

Faanes, C.A. 1983. Breeding birds of wooded draws in western North Dakota. 

Prairie Naturalist. 15: 173–187.

Fahrig, L.; Pedlar, J.H.; Pope, S.E.; Taylor, P.D.; Wegner, J.F. 1995. Effect of 

road traffic on amphibian density. Biological Conservation. 73: 177–182.

Fecske, D.M.; Jenks, J.A.; Smith, V.J. 2002. Field evaluation of a habitat-relation 

model for the American marten. Wildlife Society Bulletin. 30: 775–782.
264

GENERAL TECHNICAL REPORT PNW-GTR-907

Feller, G.M.; Pierson, E.D. 2002. Habitat use and foraging behavior of Townsend’s 

big-eared bat (Corynorhinus townsendii) in coastal California. Journal of 

Mammalogy. 83: 167–177.

Feminella, J.W.; Hawkins, C.P. 1994. Tailed frog tadpoles differentially alter their 

feeding behavior in response to non-visual cues from four predators. Journal of 

the North American Benthological Society. 13: 310–320.

Fernandez, C. 1993. The choice of nesting cliffs by golden eagles, Aquila 

chrysaetos: the influence of accessibility and disturbance by humans. Alauda.

61: 105–110.

Ficetola, G.F.; Sacchi, R.; Scali, S.; Gentilli, A.; DeBarnardi, F.; Galeotti, P. 

2007. Vertebrates respond differently to human disturbance: implications for the 

use of a focal species approach. Acta Oecologica. 31: 109–118.

Findlay, C.S.; Bourdages, J. 2000. Response time of wetland biodiversity to road 

construction on adjacent lands. Conservation Biology. 14: 86–94.

Findlay, C.S.; Houlahan, J. 1997. Anthropogenic correlates of species richness in 

southeastern Ontario wetlands. Conservation Biology. 11: 1000–1009.

Finn, S.P.; Marzluff, J.; Varland, D.E. 2002a. Does northern goshawk breeding 

occupancy vary with nest-stand characteristics on the Olympic Peninsula, 

Washington? Journal of Raptor Research. 36: 265–279.

Finn, S.P.; Marzluff, J.; Varland, D.E. 2002b. Effects of landscape and local 

habitat attributes on northern goshawk site occupancy in western Washington. 

Forest Science. 48: 1–10.

Fischer, D.L.; Ellis, K.L.; Meese, R.J. 1984. Winter habitat selection of diurnal 

raptors in central Utah. Raptor Research. 18: 98–102.

Fisher, R.N.; Shaffer, H.B. 1996. The decline of amphibians in California’s Great 

Central Valley. Conservation Biology. 10(5): 1387–1397.

Fitzgerald, J.P. 1978. Vertebrate associations in plant communities along the South 

Platte River in northeastern Colorado. In: Graul, W.D.; Bissell, S.J. eds. Lowland 

river and stream habitat in Colorado: a symposium. Greeley, CO: Colorado 

Chapter Wildlife Society and Colorado Audubon Council: 73–88.

Flanders, A.A.; Kuvlesky, W.P.; Ruthven, D.C.; Zaiglin, R.E.; Bingham, R.L.; 

Fulbright, T.E.; Hernandez, F.; Brennan, L.A. 2006. Effects of invasive exotic 

grasses on south Texas rangeland breeding birds. Auk. 123: 171–182.
265

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Fletcher, A.R.; Morison, A.K.; Hume, D.J. 1985. Effects of carp, Cyprinus 

carpio L., on communities of aquatic vegetation and turbidity of waterbodies in 

the lower Goulburn River basin. Australian Journal of Marine and Freshwater 

Research. 36: 311–327.

Fletcher, R.J.; McKinney, S.T.; Bock, C.E. 1999. Effects of recreational trails 

on wintering diurnal raptors along riparian corridors in a Colorado grassland. 

Journal of Raptor Research. 33(3): 233–239.

Fontaine, J.B.; Donato, D.C.; Robinson, W.D.; Law, B.E.; Kauffman, J.B. 2009.

Bird communities following high-severity fire: response to single and repeat fires 

in a mixed-evergreen forest, Oregon, USA. Forest Ecology and Management. 

257: 1496–1504.

Foreyt, W.J. 1989. Fatal Pasturella haemolytica pneumonia in bighorn sheep

after direct contact with clinically normal domestic sheep. American Journal 

of Veterinary Research. 50: 341–344.

Foreyt, W.J.; Jessup, D. 1982. Fatal pneumonia of bighorn sheep following 

association with domestic sheep. Journal of Wildlife Diseases. 18: 163–167.

Foreyt, W.J.; Snipes, K.P.; Kasten, R.W. 1994. Fatal pneumonia following 

inoculation of healthy bighorn sheep with Pasturella haemolytica from healthy 

domestic sheep. Journal of Wildlife Diseases. 30: 137–145.

Forristal, C.D. 2009. Influence of postfire salvage logging on black-backed 

woodpecker nest-site selection and nest survival. Bozeman, MT: Montana 

State University. 93 p. M.S. thesis. 

Forsman, E.D.; Anthony, R.G.; Dugger, K.M. [and others]. 2011. Population 

demography of northern spotted owls. Studies in Avian Biology. 40. 106 p.

Franklin, J.F.; Hemstrom, M.A.; VanPelt, R.; Buchanan, J.B. 2008. The case 

for active management of dry forests types in eastern Washington: perpetuating 

and creating old forest structures and functions. Olympia, WA: Washington State 

Department of Natural Resources.

Franklin, J.F.; Johnson, K.N. 2012. A restoration framework for federal forests in 

the Pacific Northwest. Journal of Forestry. 110(8): 429–439.

Franzreb, K.E. 1977. Bird population changes after timber harvesting of a mixed 

conifer forest in Arizona. Res. Pap. RM-184. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Forest and Range Experiment 

Station. 26 p.
266

GENERAL TECHNICAL REPORT PNW-GTR-907

Fraser, J.D.; Frenzel, L.D.; Mathisen, J.E. 1985. The impact of human activities 

on breeding bald eagles in north-central Minnesota. Journal of Wildlife 

Management. 49: 585–592.

Freudenberger, D.; Brooker, L. 2004. Development of the focal species approach 

for biodiversity conservation in the temperate agricultural zones of Australia. 

Biodiversity and Conservation. 13: 253–274.

Friedmann, H. 1963. Host relations of the parasitic cowbirds. U.S. National 

Museum Bulletin. 233.

Fule’, P.Z.; Covington, W.W.; Moore, M.M. 1997. Determining reference 

conditions for ecosystem management of southwestern ponderosa pine forests. 

Ecological Applications. 7(3): 895–908.

Funk, W.C.; Greene, A.E.; Corn, P.S.; Allendorf, F.W. 2005. High dispersal in 

a frog species suggests that it is vulnerable to habitat fragmentation. Biology 

Letters (Royal Society of London). 1: 13–16.

Fyfe, R.W.; Olendorff, R.R. 1976. Minimizing the dangers of nesting studies to 

raptors and other sensitive species. Canadian Wildlife Service. Occas. Pap. 23. 

17 p.

Gabrielson, I.N.; Jewett, S.G. 1940. Birds of Oregon. Corvallis, OR: Oregon State 

College. 650 p.

Gaines, W.L. 2000. Disturbance ecology, land allocations, and wildlife management. In: Proceedings of the management of fire maintained ecosystems 

workshop. Whistler, BC: British Columbia Forest Service: 2–9–34.

Gaines, W.L.; Haggard, M.; Begley, J.; Lehmkuhl, J.; Lyons, A.L. 2010a.

Short-term effects of thinning and burning restoration treatments on avian 

community composition, density, and nest survival in the eastern Cascades 

dry forests, Washington. Forest Science. 56(1): 88–99.

Gaines, W.L.; Haggard, M.; Lehmkuhl, J.F.; Lyons, A.L.; Harrod, R.J. 2007.

Short-term response of land birds to ponderosa pine restoration. Restoration 

Ecology. 15(4): 666–674.

Gaines, W.L.; Harrod, R.J.; Lehmkuhl, J.F. 2003. Monitoring biodiversity 

for ecoregional initiatives. In: Busch, D.E.; Trexler, J.C., eds. Monitoring 

ecosystems: interdisciplinary approaches for evaluating ecoregional initiatives. 

Washington, DC: Island Press: 377–404.
267

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Gaines, W.L.; Peterson, D.W.; Thomas, C.A.; Harrod, R.J. 2012. Adaptations to 

climate change: Colville and Okanogan-Wenatchee National Forests. Gen. Tech. 

Rep. PNW-GTR-862. Portland, OR: U.S. Department of Agriculture, Forest 

Service, Pacific Northwest Research Station. 34 p.

Gaines, W.L.; Singleton, P.H.; Ross, R.C. 2003. Assessing the cumulative 

effects of linear recreation routes on wildlife habitats on the Okanogan and 

Wenatchee National Forests. Gen. Tech. Rep. PNW-GTR-586. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

79 p.

Galen, C. 1989. A preliminary assessment of the status of Lewis’ woodpecker 

in Waso County, Oregon. Tech. Rep. 88-3-01. Portland, OR: Oregon Department 

of Fish and Wildlife.

Gallo, K.; Lanigan, S.H.; Eldred, P.; Gordon, S.N.; Moyer, C. 2005. Northwest 

Forest Plan—the first ten years (1994–2003): preliminary assessment of the 

condition of watersheds. Gen. Tech. Rep. PNW-GTR-647. Portland, OR: U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Research Station. 

133 p.

Garrett, K.L.; Raphael, M.G.; Dixon, R.D. 1996. White-headed woodpecker 

(Picoides albolarvatus). In: Poole, A.; Gill, F., eds. The birds of North America. 

No. 252. Philadelphia, PA: The Academy of Natural Sciences; Washington, DC: 

The American Ornithologists’ Union. 

Garrett, M.G.; Watson, J.W.; Anthony, R.G. 1993. Bald eagle home range 

and habitat use in the Columbia River Estuary. Journal of Wildlife Management. 

57: 19–27.

Gartner, S.; Reynolds, K.M.; Hessburg, P.F.; Hummel, S.; Twery, M. 2008.

Decision support for evaluating forest departure and prioritizing forest 

management activities in a changing environment. Forest Ecology and 

Management. 256: 1666–1676. 

Gashwiler, J.S. 1977. Bird populations in four vegetational types in central 

Oregon. Spec. Sci. Rep.–Wildl. 205. Washington, DC: U.S. Department of the 

Interior, Fish and Wildlife Service. 20 p.

Gentry, D.J.; Vierling, K.T. 2007. Old burns as source habitats for Lewis’s 

woodpeckers breeding in the black hills of South Dakota. The Condor. 109(1): 

122–131.
268

GENERAL TECHNICAL REPORT PNW-GTR-907

Germaine, H.L.; Germaine, S.S. 2006. Forest restoration treatment effects on

the nesting success of western bluebirds. (Sialia mexicana). Restoration Ecology. 

10: 326–367.

Gerrard, J.M.; Bortolotti, G.R. 1988. The bald eagle, haunts and habits of a 

wilderness monarch. Washington, DC: Smithsonian Institution Press. 177 p.

Gibbs, J.P. 1998. Amphibian movements in response to forest edges, roads, 

and streambeds in southern New England. Journal of Wildlife Management. 

62: 584–589.

Gibbs, J.P.; Longcore, J.R.; McAuley, D.G.; Ringelman, J.K. 1991. Use of 

wetland habitats by selected nongame waterbirds in Maine. Fed. Gov. Ser. Fish 

and Wildlife Research 9. U.S. Department of the Interior, Fish and Wildlife 

Service. http://pubs.er.usgs.gov/. (June 5, 2014).

Gibbs, J.P.; Melvin, S.M. 1990. An assessment of wading birds and other wetlands 

avifauna and their habitats in Maine. Report to Endangered and Nongame 

Wildlife Grants Program. Bangor, ME: Maine Department of Inland Fisheries 

and Wildlife. 

Giblisco, C.J. 1994. Distributional dynamics of modern Martes in North America. 

In: Buskirk, S.W.; Harestad, A.S.; Raphael, M.G.; Powell, R.A. eds. Martens, 

sables, and fishers: biology and conservation. Ithaca, NY: Cornell University 

Press: 59–70.

Gilbert, J.H.; Wright, J.L.; Lauten, D.J.; Probst, J.R. 1997. Den and rest-site 

characteristics of American marten and fisher in northern Wisconsin. In: Proulx, 

G.; Bryant, H.N.; Woodard, P.M., eds. Martes: taxonomy, ecology, techniques, 

and management. Edmonton, AB: Provincial Museum of Alberta: 135–145.

Gilligan, J.; Smith, M.; Rogers, D.; Contreras, A. 1994. Birds of Oregon: status 

and distribution. McMinnville, OR: Cinclus Publishing. 

Gillis, E. 1989. Western bluebirds, tree swallows & violet-green swallows west 

of the Cascade Mountains in Oregon, Washington and Vancouver Island, BC. 

Sialia. 11(4): 127–130. 

Godbout, G.; Ouellet, J. 2008. Habitat selection of American marten in a logged 

landscape at the southern fringe of the boreal forest. Ecoscience. 15: 332–342.

Goggans, R. 1989. Black-backed woodpecker (Picoides arcticus). In: Clark, T.W.; 

Harvey, A.H.; Dorn, R.D.; Genter, D.L.; Groves, C., eds. Rare, sensitive, and 

threatened species of the greater Yellowstone ecosystem. Jackson, WY: Northern 

Rockies Conservation Cooperative: 88–89.
269

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Goggans, R.; Dixon, R.D.; Seminara, L.C. 1988. Habitat use by three-toed 

and black-backed woodpeckers, Deschutes National Forest, Oregon. Nongame 

Wildlife Program Report 87-3-02. Salem, OR: Oregon Department of Fish and 

Wildlife. 43 p. 

Goguen, C.B.; Mathews, N.E. 1998. Songbird community composition and 

nesting success in grazed and ungrazed pinyon-juniper woodlands. Journal of 

Wildlife Management. 62: 474–484.

Goguen, C.B.; Mathews, N.E. 1999. Review of the causes and implications of 

the association between cowbirds and livestock. In: Morrison, M.L.; Hall, L.S.; 

Robinson, S.K.; Rothstein, S.I.; Hahn, D.C.; Rich, T.D., eds. Research and 

management of the brown-headed cowbird in western landscapes. Studies in 

Avian Biology. 18: 10–17.

Goguen, C.B.; Mathews, N.E. 2000. Local gradients of cowbird abundance and 

parasitism relative to livestock grazing in a western landscape. Conservation 

Biology. 14: 1862–1869.

Goldberg, C.S.; Waits, L.P. 2009. Using habitat models to determine conservation 

priorities for pond-breeding amphibians in a privately-owned landscape of 

northern Idaho, USA. Biological Conservation. 142: 1096–1104.

Gosse, J.W.; Cox, R.; Avery, S.W. 2005. Home-range characteristics and habitat 

use by American martens in eastern Newfoundland. Journal of Mammalogy. 

86: 1156–1163.

Grant, T.A.; Madden, E.; Berkey, G.B. 2004. Tree and shrub invasion in northern 

mixed-grass prairie: implications for breeding grassland birds. Wildlife Society 

Bulletin. 32: 807–818.

Grindal, S.D.; Morissette, J.L.; Bringham, R.M. 1999. Concentration of bat 

activity in riparian habitats over an elevational gradient. Canadian Journal of 

Zoology. 77: 972–977.

Gross, J.E.; Singer, F.J.; Moses, M.E. 2000. Effects of disease, dispersal, and 

area on bighorn sheep restoration. Restoration Ecology. 8(4S): 25–37.

Groves, C. 2003. Drafting a conservation blueprint: a practitioner’s guide to 

planning for biodiversity. Washington, DC: Island Press. 480 p.

Groves, C.; Yenson, E. 1989. Rediscovery of the northern bog lemming 

(Synaptomys borealis) in Idaho. Northwest Naturalist. 70: 14–15.
270

GENERAL TECHNICAL REPORT PNW-GTR-907

Grubb, T.G.; King, R.M. 1991. Assessing human disturbance of breeding bald 

eagles with classification tree models. Journal of Wildlife Management. 55: 

500–511.

Grubb, T.G.; Pater, L.L.; Delaney, D.K. 1998. Logging truck noise near nesting 

northern goshawks. Res. Note RMRS-RN-3. Fort Collins, CO: U.S. Department 

of Agriculture, Forest Service, Rocky Mountain Research Station. 30 p.

Guinan, J.A.; Gowaty, P.A.; Eltzroth, E.K. 2000. Western bluebird (Sialia 

mexicana). In: Poole, A.; Gill, F., eds. The birds of North America, No. 510. 

Philadelphia, PA: The Birds of North America, Inc.

Guynn, D.C., Jr.; Guynn, S.T.; Wigley, T.B.; Miller, D.A. 2004. Herbicides and 

forest biodiversity–What do we know and where do we go from here? Wildlife 

Society Bulletin. 32: 1085–1092.

Hagar, D.C. 1960. The interrelationships of logging, birds, and timber regeneration 

in the Douglas-fir region of northwestern California. Ecology. 41: 116–125.

Hager, H.A.; McCoy, K.D. 1998. The implications of accepting untested 

hypotheses: a review of the effects of purple loosestrife (Lythrum salicaria) 

in North America. Biodiversity and Conservation. 7: 1069–1079.

Haggard, M.E.; Gaines, W.L. 2001. Effects of stand-replacement fire and salvage 

logging on a cavity-nesting bird community in eastern Cascades, Washington. 

Northwest Science. 75(4): 387–396.

Haggard, M.E.; Gaines, W.L. 2008. Management considerations for forest raptors 

on the Okanogan-Wenatchee, and Colville National Forests. Wenatchee, WA: 

U.S. Department of Agriculture, Forest Service, Wenatchee National Forest.

Hahn, T.P. 1996. Cassin’s finch (Carpodacus cassinii). In: Poole, A.; Gill, F., 

eds. The Birds of North America, No. 240. Philadelphia, PA: The Academy of 

Natural Sciences; Washington, DC: The American, Ornithologist’s Union. 

Hamann, B.; Johnston, H.; McClelland, P. [et al.]. 1999. Birds. In: Joslin, G.; 

Youmans, H., coords. Effects of recreation on Rocky Mountain wildlife: a review 

for Montana. Helena, MT: Committee on Effects of Recreation on Wildlife, 

Montana Chapter of The Wildlife Society: 3.1–3.34.

Hamer, T.L.; Flather, C.H.; Noon, B.R. 2006. Factors associated with grassland 

bird species richness: the relative roles of grassland area, landscape structure, 

and prey. Landscape Ecology. 21: 569–583.
271

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Hamerstrom, F. 1969. A harrier population study. In: Hickey, J.J., ed. Peregrine 

falcon populations, their biology and decline. Madison, WI: University of 

Wisconsin Press: 367–383.

Hamerstrom, F. 1986. Harrier, hawk of the marshes: the hawk that is ruled by a 

mouse. Washington, DC: Smithsonian Institution Press. 171 p.

Hamerstrom, F.; Kopeny, M. 1981. Harrier nest-site vegetation. Journal of Raptor 

Research. 15: 86–88.

Hann, W.J.; Jones, J.L.; Karl, M.G. [et al.]. 1997. Landscape dynamics of the 

basin. Gen. Tech. Rep. PNW-GTR-405. In: Quigley, T.M.; Arbelbide, S.J., 

tech. eds. An assessment of ecosystem components in the interior Columbia 

Basin and portions of the Klamath and Great Basins: volume 2. Portland, OR: 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station: 307–1055. 4 vol. (Quigley, T.M., tech. ed.; The Interior Columbia Basin 

Ecosystem Management Project: Scientific Assessment).

Hansen, A.; McComb, W.; Vega, R.; Raphael, M.; Hunter, M. 1995. Bird 

habitat relationships in natural and managed forests in west Cascades of Oregon. 

Ecological Applications. 5: 555–569.

Hanus, S.; Wollis, H.; Wilkinson, L. 2002. Western (Aechmophors occidentalis) 

and eared (Podiceps nigricollis) grebes of central Alberta: inventory, survey 

techniques and management concerns. Edmanton, AB; Alberta Sustainable 

Resource Development Fish and Wildlife Division Species at Risk Report 41.

Hargis, C.D.; Bissonette, J.A. 1997. Effects of forest fragmentation on populations 

of American marten in the intermountain West. In: Proulx, G.; Bryant, H.N.; 

Woodard, P.M., eds. Martes: taxonomy, ecology, techniques, and management. 

Edmonton, AB; Provincial Museum of Alberta: 437–451.

Hargis, C.D.; Bissonette, J.A.; Turner, D.L. 1999. The influence of forest 

fragmentation and landscape pattern on American martens. Journal of Applied 

Ecology. 36: 157–172.

Hargis, C.D.; McCarthy, C.; Perloff, R.D. 1994. Home ranges and habitats of 

northern goshawks in eastern California. Studies in Avian Biology. 16: 66–74.

Harmata, A.R.; Oakleaf, B. 1992. Bald eagles in the greater Yellowstone 

ecosystem: an ecological study with emphasis on the Snake River, Wyoming. 

Cheyenne, WY: Wyoming Game and Fish Department. 
272

GENERAL TECHNICAL REPORT PNW-GTR-907

Harris, M.A. 1982. Habitat use among woodpeckers in forest burns. Missoula, 

MT: University of Montana. 62 p. M.S. thesis. 

Harrison, H.H. 1979. A field guide to western birds’ nests. Boston, MA: Houghton 

Mifflin Company. 279 p.

Harrod, R.J.; Gaines, W.L.; Hartl, W.E.; Camp, A. 1998. Estimating historical 

snag densities in dry forests east of the Cascade Range. Gen. Tech. Rep. PNWGTR-428. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 16 p.

Harrod, R.J.; McRae, B.H.; Hartl, W.E. 1989. Historical stand reconstruction in 

ponderosa pine forests to guide silvicultural prescriptions. Forest Ecology and 

Management. 114: 433–446.

Harrod, R.J.; Povak, N.K.; Peterson, D.W. 2007. Comparing the effectiveness of 

thinning and prescribed fire for modifying structure in dry coniferous forests. 

[CD-ROM]. In: Bulter, B.W.; Cook, W., comps. The fire environment-innovations, 

management, and policy. RMRS-P-46CD. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station: 329–346.

Harvey, D.; Knight, J.; Cantebury, G. 2000. Proposed rule: California tiger 

salamander Ambystoma californiense. Sacramento, CA: U.S. Department of the 

Interior, Fish and Wildlife Service. 

Havera, S.P.; Boens, L.R.; Georgi, M.M.; Shealy, R.T. 1992. Human disturbance 

of waterfowl on Keokuk Pool, Mississippi River. Wildlife Society Bulletin. 20: 

290–298.

Hayes, G.E.; Buchanan, J.B. 2002. Washington State status report for the peregrine 

falcon. Olympia, WA: Washington Department of Fish and Wildlife. 77 p.

Hayes, J.P. 1997. Temporal variation in activity of bats and the design of 

echolocation-monitoring studies. Journal of Mammalogy. 62: 233–243.

Hayes, J.P. 2003. Habitat ecology and conservation of bats in western coniferous 

forests. In: Zabel, C.J.; Anthony, R.G., eds. Mammal community dynamics in 

coniferous forests of western North America: management and conservation. 

Cambridge, MA: Cambridge University Press: 81–119 p.

Hayes, J.P.; Loeb, S.C. 2007. The influences of forest management on bats in 

North America. In: Lacki, M.J.; Hayes, J.P.; Kurta, A., eds. Bats in forests 

conservation and management. Baltimore, MD: John Hopkins University Press: 

207–235.
273

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Hayes, M. P. 1997. Status of the Oregon spotted frog (Rana pretiosa sensu stricto) 

in the Deschutes Basin and selected other systems in Oregon and northeastern 

California with a rangewide synopsis of species’ status. Final report prepared for 

The Nature Conservancy under contract to the U.S. Fish and Wildlife Service. 

Portland, OR. 57 p. plus appendices.

Hayes, M.P.; Jennings, M.R. 1986. Decline of ranid frog species in Western North 

America: are bullfrogs (Rana catesbeiana) responsible? Journal of Herpetology. 

20: 490–509.

Hays, D.W.; Milner, R.L. 1999. Peregrine falcon, Falco peregrinus. In: 

Management recommendations for Washington’s priority species. Volume IV: 

Birds. Olympia, WA: Washington Department of Fish and Wildlife: 11–1 to 11–4.

Hayward, G.D.; Hayward, P.H.; Garton, E.O. 1993. Ecology of boreal owls in 

the northern Rocky Mountains. Wildlife Monograph No. 124: 1–59.

Heady, P.H.; Frick, W.F. 2001. Bat inventory of Muir Woods National Monument. 

Final report. Aptos, CA; Central Coast Bat Research Group.

Hecht, W.R. 1951. Nesting of the marsh hawk at Delta, Manitoba. Wilson Bulletin. 

63: 167–176.

Hecnar, S.J.; M’Closkey, R.T. 1997. The effects of predatory fish on amphibian 

species richness and distribution. Biological Conservation. 79: 123–131.

Hedges, S. 1994. Utah’s bluebirds. Utah Birds. 10(1): 7–8. 

Herkert, J.R.; Simpson, S.A.; Westemeier, R.L.; Esker, T.L.; Walk, J.W. 1999.

Response of northern harriers and short-eared owls to grassland management in 

Illinois. Journal of Wildlife Management. 63: 517–523.

Herlugson, C.J. 1980. Biology of sympatric populations of western and mountain 

bluebirds. Pullman, WA: Washington State University. 133 p. Ph.D. dissertation.

Herrington, R.E.; Larsen, J.H. 1985. Current status, habitat requirements, and 

management of the larch mountain salamander Plethodon larselli. Biological 

Conservation. 34: 169–179.

Hessburg, P.F.; Agee, J.K. 2003. An environmental narrative of inland Northwest 

US forests, 1800-2000. Forest Ecology and Management. 178: 23–59.

Hessburg, P.F.; Agee, J.K.; Franklin, J.F. 2005. Dry forests and wildland fires 

of the inland Northwest USA: contrasting the landscape ecology of the presettlement and modern eras. Forest Ecology and Management. 211: 117–139.
274

GENERAL TECHNICAL REPORT PNW-GTR-907

Hessburg, P.F.; James, K.M.; Salter, R.B. 2007. Re-examining fire severity 

relations in pre-management era mixed conifer forests: inferences from 

landscape patterns of forest structure. Landscape Ecology. 22(1): 5–24.

Hessburg, P.F.; Smith, B.G.; Kreiter, S.G.; Miller, C.A.; Salter, R.B.; 

McNicholl, C.H.; Hann, W.J. 1999a. Historical and current forest and range 

landscapes in the interior Columbia River basin and portions of the Klamath and 

Great Basins. Part 1. Linking vegetation patterns and landscape vulnerability 

to potential insect and pathogen disturbances. Gen. Tech. Rep. PNW-GTR-458. 

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest 

Research Station. 357 p.

Hessburg, P.F.; Smith, B.G.; Salter, R.B. 1999b. Using estimates of natural 

variation to detect ecologically important change in forest spatial patterns: a case 

study, Cascade Range, eastern Washington. Res. Rep. PNW-RP-514. Portland, 

OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 65 p.

Hessburg, P.F.; Smith, B.G.; Salter, R.B.; Ottmar, R.D.; Alvarado, E. 2000.

Recent changes (1930s–1990s) in spatial patterns of interior northwest forests, 

USA. Forest Ecology and Management. 136: 53–83.

Hessburg, P.F.; Reynolds, K.M.; Salter, R.B.; Dickinson, J.D.; Gaines, W.L.; 

Harrod, R.J. 2013. Landscape evaluation for restoration planning on the 

Okanogan-Wenatchee National Forest, USA. Sustainability. 5: 805–840.

Hicks, L.L.; Elder, J.M. 1979. Human disturbance of Sierra Nevada bighorn 

sheep. Journal of Wildlife Management. 43(3): 909–915.

Hill, R.A. 1976. Host-parasite relationships of the brown-headed cowbird in a 

prairie habitat of west-central Kansas. Wilson Bulletin. 88: 555–565.

Hirner, J.L.M.; Cox, S.P. 2007. Effects of rainbow trout (Oncorhynchus mykiss) 

on amphibians in productive recreational fishing lakes of British Columbia. 

Canadian Journal of Fisheries and Aquatic Sciences. 64: 1770–1780.

Hodges, K.E. 1999. Ecology of snowshoe hares in southern boreal and montane 

forests. In: Ruggiero, L.F.; Aubry, K.B.; Buskirk, S.W.; Koehler, G.M.; Krebs, 

C.J.; McKelvey, K.S.; Squires, J.R. Ecology and conservation of lynx in the 

United States. Gen. Tech. Rep. RMRS-GTR-30WWW. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station: 

163–206. Chapter 7.
275

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Hodgman, T.P.; Harrison, D.J.; Katnik, D.D.; Elowe, K.D. 1994. Survival 

in an intensively trapped marten population in Maine. Journal of Wildlife 

Management. 58: 593–600.

Hollenbeck, R.R. 1974. Growth rates and movements within a population of Rana 

pretiosa pretiosa Baird and Girard in south central Montana. Bozeman, MT: 

Montana State University. 65 p. Ph.D. dissertation. 

Holmes, A.L. 2007. Short-term effects of a prescribed burn on songbirds and 

vegetation in mountain big sagebrush. Western North American Naturalist. 

67: 292–298.

Holmes, T.L.; Knight, R.L.; Stegall, L.; Craig, G.R. 1993. Responses of 

wintering grassland raptors to human disturbance. Wildlife Society Bulletin. 

21: 461–468.

Holthausen, R. 2002. White paper on managing for population viability. 

Unpublished report. On file with: U.S. Department of Agriculture, Forest 

Service, Washington, DC. 

Holthausen, R.S.; Raphael, M.G.; Samson, F.B.; Ebert, D.; Heibert, R.; 

Manesco, K. 1999. Population viability in ecosystem management. In: Sexton, 

W.T.; Malk, A.J.; Szaro, R.C.; Johnson, N.C., eds. Ecological stewardship: 

a common reference for ecosystem management, Vol. II. Kidlington, The 

Netherlands: Elsevier Science: 135–156.

Holthuijzen, A.M.A.; Eastland, W.G.; Ansell, A.R.; Kochert, M.N.; Williams, 

R.D.; Young, L.S. 1990. Effects of blasting on behavior and productivity of 

nesting prairie falcons. Wildlife Society Bulletin. 18: 270–281.

Houlahan, J.E.; Findlay, C.S. 2003. The effects of adjacent land use on wetland 

amphibian species richness and community composition. Canadian Journal of 

Fish and Aquatic Science. 60: 1078–1094.

Hoyt, S.F. 1957. The ecology of the pileated woodpecker. Ecology. 38: 246–256.

Huff, M.; Brown, M. 1998. Four yeas of bird point count monitoring in latesuccessional conifer forests and riparian areas from the Pacific Northwest 

national forests, interim results. Sandy, OR: U.S. Department of Agriculture, 

Forest Service. 142 p.

Huggett, A.J. 2005. The concept and utility of ‘ecological thresholds’ in 

biodiversity conservation. Biological Conservation. 124: 301–310.
276

GENERAL TECHNICAL REPORT PNW-GTR-907

Humes, M.L.; Hayes, J.P.; Collopy, M.W. 1999. Bat activity in thinned, 

unthinned, and old-growth forests in western Oregon. Journal of Wildlife 

Management. 63: 553–561. 

Humphrey, S.R.; Kunz, T.H. 1976. Ecology of a Pleistocene relict, the western 

big-eared bat (Plecotus townsendii), in the southern Great Plains. Journal of 

Mammalogy. 57: 470–494.

Hunt, W.G.; Jackman, R.E.; Brown, T.L.; Gilardi, J.G.; Driscoll, D.E.; Culp, 

L. 1995. A pilot golden eagle population study in the Altamont Pass Wind 

Resource Area, California. Report to National Renewable Energy Laboratory. 

Subcontract No. XCG-4-14200. Santa Cruz, CA: Predatory Bird Research Group, 

University of California. 

Hunt, W.G.; Jackman, R.E.; Hunt, T.L.; Driscoll, D.E.; Culp, L. 1999. A 

population study of golden eagles in the Altamont Pass Wind Resource Area; 

population trend analysis 1994–1997. Santa Cruz, CA: Predatory Bird Research 

Group, University of California.

Hunter, M.L.; Jacobson, G.L., Jr.; Webb, T., III. 1988. Paleoecology and the 

coarse-filter approach to maintaining biological diversity. Conservation Biology. 

4: 375–384.

Hutto, R.L. 1995a. U.S.F.S. Northern Region Songbird Monitoring Program: 

distribution and habitat relationships. Internal report. Missoula, MT: U.S. 

Department of Agriculture, Forest Service, Northern Region. 

Hutto, R.L. 1995b. Composition of bird communities following stand-replacement 

fires in northern Rocky Mountain (U.S.A.) conifer forests. Conservation Biology. 

9: 1041–1058.

Hutto, R.L. 2006. Toward meaningful snag-management guidelines for postfire 

salvage logging in North American conifer forests. Conservation Biology. 20(4): 

984–993.

Huxel, G.R.; Hastings, A. 1999. Habitat loss, fragmentation and restoration. 

Restoration Ecology. 7: 309–315.

Idaho State Conservation Effort. 1995. Habitat conservation assessment and 

conservation strategy for the Townsend’s big-eared bat. Unpublished report. On 

file with: U.S. Department of Agriculture, Forest Service, U.S. Department of 

the Interior, Bureau of Land Management; Interior Columbia Basin Ecosystem 

Management Project, 304 N. 8th Street, Boise, ID 83702.
277

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Ingelfinger, F.; Anderson, S. 2004. Passerine response to roads associated with 

natural gas extraction in a sagebrush steppe habitat. Western North American 

Naturalist. 64: 385–395.

Interagency Lynx Biology Team. 2013. Canada lynx conservation assessment and 

strategy. 3rd ed. Forest Service Publication R1-13-19. Missoula, MT: USDA Forest 

Service, USDI Fish and Wildlife Service, USDI Bureau of Land Management, 

and USDI National Park Service. 128 p.

International Union for the Conservation of Nature [IUCN]. 2000. International 

Union for the Conservation of Nature Red List Categories. Gland, Switzerland.

Jacobson, W.B. 1972. Relative abundance of the avian population along the South 

Platte River flood plain at the proposed Narrows Reservoir site. Greeley, CO: 

University of Northern Colorado. 82 p. M.S. thesis. 

Jewett, S.G.; Taylor, W.P.; Shaw, W.T.; Aldrich, J.W. 1953. Birds of Washington 

state. Seattle, WA: University of Washington Press. 768 p.

Johnsgard, P.A. 1987. Diving birds of North America. Lincoln, NE: University of 

Nebraska Press. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1012

&context=bioscidivingbirds. (June 6, 2014).

Johnsgard, P.A. 1990. Hawks, eagles, and falcons of North America: biology and 

natural history. Washington, DC: Smithsonian Institution. 

Johnson, D.H.; Igle, L.D. 2001. Area requirements of grassland birds: a regional 

perspective. The Auk. 118(1): 24–34.

Johnson, D.H.; O’Neil, T.A., eds. 2001. Wildlife-habitat relationships in Oregon 

and Washington. Corvallis, OR: Oregon State University Press. 736 p.

Johnson, R. 1999. Washington. In: Toweill, D.E.; Geist, V. eds. Return of royality: 

wild sheep of North America. Missoula, MT: Boone and Crockett Club and 

Foundation for North American Wild Sheep: 112, 152.

Johnson, R.E. 1977. An historical ananysis of wolverine abundance and 

distribution in Washington. The Murrelet. 58: 13–16.

Johnson, R.E.; Cassidy, K.M. 1997. Terrestrial mammals of Washington state: 

Location data and predicted distributions. Volume 3 in Washington State Gap 

Analysis–final report. In: Cassidy, K.M.; Grue, C.E.; Smith, M.R.; Dvornich, 

K.M., eds. Seattle, WA: Washington Cooperative Fish and Wildlife Research 

Unit, University of Washington. 304 p.
278

GENERAL TECHNICAL REPORT PNW-GTR-907

Johnson, R.G.; Temple, S.A. 1990. Nest predation and brood parasitism of 

tallgrass prairie birds. Journal of Wildlife Management. 54: 106–111.

Johnson, R.R.; Haight, L.T. 1984. Riparian problems and initiatives in the 

American Southwest: a regional perspective. In: Warner, R.E.; Hendrix, 

K.M., eds. California riparian systems: ecology, conservation, and productive 

management. Berkeley, CA: University of California Press: 404–412.

Johnson, T.H.; Wauer, R.H. 1996. Avifaunal response to the 1977 La Mesa fire. 

In: Allen, C.D., tech. ed. fire effects in southwestern forests. Proceedings of the 

second La Mesa Fire symposium. Gen. Tech. Rep. RM-GTR-286. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station: 70–94.

Johnson, T.L.; Swift, D.M. 2000. A test of a habitat evaluation procedure for 

Rocky Mountain bighorn sheep. Restoration Ecology. 8(4S): 47–56.

Jones, Z.F.; Bock, C.E 2002. Conservation of grassland birds in an urban 

landscape: a historical perspective. Condor. 104: 643–651.

Kadera, J. 1987. Trees’ future obscured by forest of rules. Oregonian. January 25; 

Sect. C: 1–4.

Kaisanlahti-Jokimäki, M.-L.; Jokimäki, J.; Huhta, E.; Ukkola, M.; Helle, 

P.; Ollila, T. 2008. Territory occupancy and breeding success of the golden 

eagle (Aquila chrysaetos) around tourist destinations in northern Finland. Ornis 

Fennica. 85: 2–12.

Kalcounis-Ruppell, M.C.; Psyllakis, J.M.; Brigham, R.M. 2005. Tree roost 

selection by bats: an empirical synthesis using meta-analysis. Wildlife Society 

Bulletin. 33: 1123–1132.

Kantrud, H.A.; Higgins, K.F. 1992. Nest and nest site characteristics of some 

ground-nesting, non-passerine birds of northern grasslands. Prairie Naturalist. 

24: 67–84.

Kantrud, H.A.; Kologiski, R.L. 1982. Effects of soils and grazing on breeding 

birds of uncultivated upland grasslands of the northern Great Plains. Wildlife 

Research Report 15. Washington, DC: U.S. Fish and Wildlife Service. 33 p.

Kantrud, H.A.; Stewart, R.E. 1984. Ecological distribution and crude density 

of breeding birds on prairie wetlands. Journal of Wildlife Management. 48: 

426–437.
279

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Keinath, D.A. 2004. Fringed myotis (Myotis thysanodes): a technical conservation 

assessment. [Online]. USDA Forest Service, Rocky Mountain Region. http://

www.fs.fed.us/r2/projects/scp/assessments/fringedmyotis.pdf. (June 15, 2010).

Kelsall, J.P. 1981. COSEWIC status report on the wolverine, Gulo gulo, in Canada. 

Ottawa, ON: Committee on the Status of Endangered Wildlife in Canada. 50 p.

Kennedy, P.L.; Ward, J.M.; Rinker, G.A.; Gessaman, J.A. 1994. Post-fledgling 

areas in northern goshawk home ranges. Studies in Avian Biology. 16: 75–82.

Kerley, L.L.; Anderson, S.H. 1995. Songbird responses to sagebrush removal in a 

high elevation sagebrush steppe ecosystem. Prairie Naturalist. 27: 129–146.

Kibbe, D.P. 1975. The nesting season June 1–July 31, 1975. Niagara-Champlain 

Region. American Birds. 29: 967–970.

Kimsey, B.; Conley, M.R. 1988. Habitat use by raptors in southcentral New 

Mexico. In: Glinski, R.L.; Pendleton, B.G.; Moss, M.B.; LeFranc, M.N., 

Jr.; Millsap, B.A.; Hoffman, S.W., eds. Proceedings of the southwest raptor 

management symposium and workshop. National Wildlife Federation Scientific 

and Technical Series. 11: 197–203.

King, M.M.; Workman, G.W. 1986. Response of desert bighorn sheep to human 

harassment: management implications. North American Wildlife and Natural 

Resources Conference. 51: 74–85.

Kirk, D.A.; Hobson, K.A. 2001. Bird-habitat relationships in jack pine boreal 

forests. Forest Ecology and Management. 147: 217–243.

Kirk, T.A.; Zielinski, W.J. 2009. Developing and testing a landscape habitat 

suitability model for the American marten (Martes americana) in the Cascades 

mountains of California. Landscape Ecology. 24: 759–773.

Klopatek, J.M.; Olson, R.J.; Emerson, J.L. 1979. Land use conflicts with natural 

vegetation in the United States. Environmental Conservation. 6: 191–200.

Knapp, R.A.; Hawkins, C.P.; Ladau, J.; McClory, J.G. 2005. Fauna of Yosemite 

National Park lakes has low resistance but high resilience to fish introductions. 

Ecological Applications. 15: 835–847.

Knapp, R.A.; Matthews, K.R.; Preisler, H.K.; Jellison, R. 2003. Developing 

probabilistic models to predict amphibian site occupancy in a patchy landscape. 

Ecological Applications. 13: 1069–1082.
280

GENERAL TECHNICAL REPORT PNW-GTR-907

Knapp, R.A.; Matthews, K.R.; Sarnelle, O. 2001. Resistance and resilience 

of alpine lake faunal assemblages to fish introductions. Ecological Monographs. 

71: 401–421.

Knick, S.T.; Rotenberry, J.T. 1995. Habitat relationships and breeding birds on the 

Snake River Birds of Prey Area. Boise, ID: Idaho Bureau of Land Management 

Technical Bulletin 95-5. 9 p.

Knick, S.T.; Rotenberry, J.T. 1997. Landscape characteristics of disturbed 

shrubsteppe habitats in southwestern Idaho. Landscape Ecology. 12: 287–297.

Knick, S.T.; Rotenberry, J.T. 2002. Effects of habitat fragmentation on passerine 

birds breeding in intermountain shrub steppe. In: George, T.L.; Dobkin, D.S., 

eds. Effects of habitat fragmentation on birds in western landscapes: contrasts 

with paradigms from the eastern United States. Studies in Avian Biology. 25. 

130–140.

Knopf, F.L.; Sedgwick, J.A.; Cannon, R.W. 1988. Guild structure of a riparian 

avifauna relative to seasonal cattle grazing. Journal of Wildlife Management. 52: 

280–290.

Kochert, M.N. 1989. Responses of raptors to livestock grazing in the Western 

United States. In: Pendleton, B.G., ed. Proceedings of the western raptor 

management symposium. National Wildlife Federation Scientific and Technical 

Series 12: 194–203.

Kochert, M.N.; Steenhof, K.; Carpenter, L.B.; Marzluff, J.M. 1999. Effects of 

fire on golden eagle territory occupancy and reproductive success. Journal of 

Wildlife Management. 63: 773–780.

Kochert, M.N.; Steenhof, K.; McIntyre, C.L.; Craig, E.H. 2002. Golden eagle 

(Aquila chrysaetos). Number 684. In: Poole, A.; Gill, F., eds. The birds of North 

America. Philadelphia, PA: The Academy of Natural Sciences; Washington, DC: 

The American Ornithologists’ Union. 

Koehler, G.M. 1990. Population and habitat characteristics of lynx and snowshoe 

hares in north central Washington. Canadian Journal of Zoology. 68: 845–851.

Koehler, G.M.; Aubry, K.B. 1994. Lynx. In: Ruggerio, L.F.; Aubry, K.B.; Buskirk, 

S.W.; Lyon, L.J.; Zielinski, W.J., tech. coords. The scientific basis for conserving 

forest carnivores: American marten, fisher, lynx and wolverine in the United 

States. Gen. Tech. Rep. GTR-RM-25. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station: 74–98.
281

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Koehler, G.M.; Maletzke, B.J.; Von Kienast, J.A.; Aubry, K.B.; Wielgus, 

R.B.; Naney, R.H. 2008. Habitat fragmentation and the persistence of lynx 

populations in Washington state. Journal of Wildlife Management. 72(7): 

1518–1524.

Koehler, G.M.; Moore, W.R.; Taylor, R.A. 1975. Preserving the pine marten: 

management guidelines for western forests. Western Wildlife. 2: 31–36.

Kolbe, J.A.; Squires, J.R.; Pletscher, D.H.; Ruggiero, L.F. 2007. The effect of 

snowmobile trails on coyote movements within lynx home ranges. Journal of 

Wildlife Management. 71: 1409–1418.

Kotliar, N.B.; Hejl, S.J.; Hutto, R.L.; Saab, V.A.; Melcher, C.P.; McFadzen, 

M.E. 2002. Effects of fire and post-fire salvage logging on avian communities in 

conifer-dominated forests of the western United States. Studies in Avian Biology. 

25: 49–64.

Krausman, P.R., ed. 1996. Rangeland wildlife. Denver, CO: Society for Range 

Management. 440 p.

Krebs, J.A.; Lewis, D. 1999. Wolverine ecology and habitat use in the North 

Columbia Mountains: progress report. British Columbia, Canada: Columbia 

Basin Fish and Wildlife Compensation Program.

Krebs, J.A.; Lofroth, E.C.; Parfitt, I. 2007. Multiscale habitat use by wolverines 

in British Columbia, Canada. Journal of Wildlife Management. 71(7): 2180–2192.

Kreisel, K.J.; Stein, S.J. 1999. Bird use of burned and unburned coniferous forests 

during winter. Wilson Bulletin. 111: 243–250.

Kroodsma, D.E.; Verner, J. 1997. Marsh wren (Cistothorus palustris). In: Poole, 

A.; Gill, F. eds. The Birds of North America, No. 308. Philadelphia, PA: The 

Birds of North America, Inc.

Kuchel, C.R. 1977. Some aspects of the behavior and ecology of harlequin ducks 

in Glacier National Park, Montana. Missoula, MO: University of Montana. 314 p. 

M.S. thesis. 

Kunz, T. H.; Martin, R.A. 1982. Plecotus townsendii. Mammalian Species. 

175: 1–6.

Laliberte, A.S.; Ripple, W.J. 2004. Range contractions of North American 

carnivores and ungulates. Bioscience. 54: 123–138.

Lambeck, R.J. 1997. Focal species: a multi-species umbrella for nature 

conservation. Conservation Biology. 11: 849–856.
282

GENERAL TECHNICAL REPORT PNW-GTR-907

Landres, P.B.; Morgan, P.; Swanson, F.J. 1999. Overview of the use of natural 

range of variability concepts in managing ecological systems. Ecological 

Applications. 9(4): 1179–1188.

Landres, P.B.; Verner, J.; Thomas, J.W. 1988. Ecological use of vertebrate 

indicator species: a critique. Conservation Biology. 2: 316–328.

Lanier, J.W.; Joseph, R.A. 1989. Managing human recreational impacts on hacked 

or free-ranging peregrines. In: Pendleton, B.A.G., ed. Proceedings of the western 

raptor management symposium and workshop. National Wildlife Federation 

Scientific and Technical Series No. 12: 149–153.

Lawler, J.J.; Mathias, M. 2007. Climate change and the future of biodiversity in 

Washington. Report prepared for the Washington Biodiversity Council. Seattle, 

WA: University of Washington. 42 p. 

Layser, E.F.; Burke, T.E. 1973. The northern bog lemming and its unique habitat 

in northeastern Washington. The Murrelet. 54(1): 7–8.

Leege, T.A.; Herman, D.J.; Zamora, B. 1981. Effects of cattle grazing on 

mountain meadows in Idaho. Journal of Range Management. 34: 324–328.

Lehmkuhl, J.F.; Burger, E.D.; Drew, E.K.; Lindsey, J.P.; Haggard, M.; 

Woodruff, K.Z. 2007b. Breeding birds in riparian and upland dry forests of the 

Cascade range. Journal of Wildlife Management. 71: 2632–2643.

Lehmkuhl, J.F.; Everett, R.L.; Schellhaas, R. [et al.]. 2003. Cavities in snags 

along a wildfire chronosequence in eastern Washington. Journal of Wildlife 

Management. 67(1): 219–228.

Lehmkuhl, J.F.; Lyons, A.L.; Bracken, E.; Leingang, J.; Gaines, W.L.; Dodson, 

E.K.; Singleton, P.H. 2013. Forage composition, productivity, and utilization in 

eastern Washington Cascade Range. Northwest Science. 87(3): 207–231.

Lehmkuhl, J.F.; Kennedy, M.; Ford, E.D.; Singleton, P.H.; Gaines, W.L.; Lind, 

R.L. 2007a. Seeing the forest for the fuels: integrating ecological values and 

fuels management. Forest Ecology and Management. 246: 73–80.

Lehmkuhl, J.F.; Kie, J.G.; Bender, L.C.; Servheen, G.; Nyberg, H. 2001.

Evaluating the effects of ecosystem management alternatives on elk, mule 

deer, and white-tailed deer in the interior Columbia River basin, U.S.A. Forest 

Ecology and Management. 153: 89–104.
283

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Lehmkuhl, J.F.; Raphael, M.G.; Holthausen, R.S.; Hickenbottom, J.R.; Naney, 

R.H.; Shelly, J.S. 1997. Historical and current status of terrestrial species and 

the effects of the proposed alternatives. In: Quigley, T.M.; Lee, K.M.; Arbelbide, 

S.J., eds. Evaluation of EIS alternatives by the Science Integration Team. Gen. 

Tech. Rep. PNW-GTR-406. Portland, OR: U.S. Department of Agriculture, 

Forest Service, Pacific Northwest Research Station: 537–730.

Leonard, M.L.; Picman, J. 1986. Why are nesting marsh wrens and yellowheaded blackbirds spatially segregated? Auk. 103: 135–140.

Leonard, W.P.; Brown, H.A.; Jones, L.L.C.; McAllister, K.R.; Storm, R.M. 

1993. Amphibians of Washington and Oregon. Seattle, WA: Seattle Audubon 

Society. 169 p.

Leslie, D.M.; Douglas, C.L. 1980. Human disturbance at water sources of the 

desert bighorn sheep. Wildlife Society Bulletin. 8(4): 284–290.

Lewis, J.C.; Kraege, D. 2000. Cavity nesting ducks. In: Management 

recommendations for Washington’s priority species. Volume IV: Birds. Olympia, 

WA: Washington Department of Fish and Wildlife: 4–1 to 4–6.

Lindenmayer, D.B.; Franklin, J.F.; Fischer, J. 2006. General management 

principles and a checklist of strategies to guide forest biodiversity conservation. 

Biological Conservation. 131: 433–445.

Lindenmayer, D.B.; Luck, G. 2005. Synthesis: thresholds in conservation and 

management. Biological Conservation. 124: 351–354.

Lindenmayer, D.B.; Manning, A.D.; Smith, P.L.; Possingham, H.P.; Fischeer, 

J.; Oliver, I.; McCarthy, M.A. 2002. The focal-species approach and landscape 

restoration: a critique. Conservation Biology. 16(2): 338–345.

Linder, E.T.; Klaus, N.A.; Buehler, D.A. 2004. Population viability as a measure 

of forest sustainability. In: Rauscher, H.M.; Johnsen, K., eds. Southern forest 

science: past, present, and future. Gen. Tech. Rep. GTR-SRS-75. Asheville, NC: 

U.S. Department of Agriculture, Forest Service, Southeast Research Station: 

307–317.

Linder G.; Wyant, J.; Meganck, R.; Williams, B. 1991. Evaluating amphibian 

responses in wetlands impacted by mining activities in the Western United 

States. In: Comer, R.D.; Davis, P.R.; Foster, S.Q.; Grant, C.V.; Rush, R.;

Thorne, O., II; Todd, J., eds. Issues and technology in the management of 

impacted wildlife. Boulder, CO: Thorne Ecological Institute: 17–25.
284

GENERAL TECHNICAL REPORT PNW-GTR-907

Linder, K.A.; Anderson, S.H. 1998. Nesting habitat of Lewis’s woodpeckers in 

southeastern Wyoming. Journal of Field Ornithology. 69: 109–116.

Linders, M.J.; Stinson, D.W. 2007. Washington State Recovery Plan for the 

Western Gray Squirrel. Olympia, WA: Washington Department of Fish and 

Wildlife. 128 p.

Linders, M.J.; West, S.D.; Vander Haegen, M. 2004. Seasonal variability in the 

use of space by western gray squirrels in southcentral Washington. Journal of 

Mammalogy. 85: 511–516.

Linner, S.C. 1980. Resource partitioning in breeding populations of marsh hawks 

and short-eared owls. Logan, UT: Utah State University. 66 p. M.S. thesis. 

Linz, G.M.; Blixt, D.C.; Bergman, D.L.; Bleier, W.J. 1996. Responses of redwinged blackbirds, yellow-headed blackbirds and marsh wrens to glyphosateinduced alterations in cattail density. Journal of Field Ornithology. 67: 167–176.

Loeb, S.C.; Waldrop, T.A. 2007. Bat activity in relation to fire and fire surrogate 

treatments in southern pine stands. Forest Ecology and Management. 255: 

3185–3192.

López-López, P.; Garcia-Ripollés, C.; Soutullo, Á.; Cadahia, L.; Urios, V. 2007.

Identifying potentially suitable nesting habitat for golden eagles applied to 

‘important bird areas’ design. Animal Conservation. 10: 208–218.

Ludwig, J.A.; Reynolds, J.F. 1988. Statistical ecology. New York: John Wiley 

and Sons. 337 p.

Lunde, R.E.; Harestad, A.S. 1986. Activity of little brown bats in coastal forests. 

Northwest Science. 60: 206–209.

Lunney, D.; Curtin, A.; Ayers, D.; Cogger, H.J.; Dickman, C.R. 1996. An 

ecological approach to identifying the endangered fauna of New South Wales. 

Pacific Conservation Biology. 2: 212–231.

Lusk, J.J.; Wells, K.S.; Guthery, F.S.; Fuhlendorf, S.D. 2003. Lark sparrow 

(Chondestes grammacus) nest-site selection and success in a mixed-grass prairie. 

Auk. 120: 120–129.

Lyons, A.L.; Gaines, W.L.; Lehmkuhl, J.F.; Harrod, R.J. 2008. Short-term 

effects of fire and fire surrogate treatments on foraging tree selection by 

cavity-nesting birds in dry forests of central Washington. Forest Ecology and 

Management. 255: 3203–3211.
285

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

MacArthur, R.A.; Geist, V.; Johnston, R.H. 1982. Cardiac and behavioral 

responses of mountain sheep to human disturbance. Journal of Wildlife 

Management. 46(2): 351–358.

MacArthur, R.A.; Johnston, R.H.; Geist, V. 1979. Factors influencing heart rate 

in free-ranging bighorn sheep: a physiological approach to the study of wildlife 

harassment. Canadian Journal of Zoology. 57: 2010–2021.

Machtans, C.S.; Latour, P.B. 2003. Boreal forest songbird communities of the 

Liard Valley, Northwest Territories, Canada. Condor. 105: 27–44.

Maclaren, P.A. 1986. Resource partitioning in an assemblage of breeding raptors 

from southeast Wyoming. Laramie, WY: University of Wyoming. 64 p. M.S. 

thesis.

MacWhirter, R.B.; Bildstein, K.L. 1996. Northern harrier (Circus cyaneus). 

In: Poole, A.; Gill, F., eds. The birds of North America, No. 210. Philadelphia, 

PA: The Academy of Natural Sciences; Washington, DC: The American 

Ornithologists’ Union. 

Maletzke, B.J.; Koehler, G.M.; Wielgus, R.B.; Aubry, K.B.; Evans, M.A. 2008.

Habitat conditions associated with lynx hunting behavior during winter in 

northern Washington. Journal of Wildlife Management. 72(7): 1473–1478.

Maletzke, B.T. 2004. Winter habitat selection of lynx in northern Washington. 

Pullman, WA: Washington State University. 48 p. M.S. thesis. 

Manci, K.M.; Rusch, D.H. 1988. Indices to distribution and abundance of some 

inconspicuous waterbirds on Horicon Marsh. Journal of Field Ornithology. 59: 

67–75.

Mannan, R.W. 1984. Summer area requirements of pileated woodpeckers in 

western Oregon. Wildlife Society Bulletin. 12: 265–268.

Marcot, B.G. 1984. Winter use of some northwestern California caves by western 

big-eared bats and long-eared myotis. Murrelet. 65: 46.

Marcot, B.G. 2006. Habitat modeling for biodiversity conservation. Northwest 

Naturalist. 87: 56–65.

Marcot, B.G.; Hohenlohe, P.A.; Morey, S.; Holmes, R.; Molina, R.; Turley, 

M.C.; Huff, M.H.; Laurence, J.A. 2006a. Characterizing species at risk II: 

using Bayesian belief networks as decision support tools to determine species 

conservation categories under the Northwest Forest Plan. Ecology and Society. 

URL:http://www.ecologyandsociety.org/vol11/iss2/art12. (June 15, 2010). 
286

GENERAL TECHNICAL REPORT PNW-GTR-907

Marcot, B.G.; Holthausen, R.S.; Raphael, M.G.; Rowland, M.M.; Wisdom, 

M.J. 2001. Using Bayesian belief networks to evaluate fish and wildlife 

population viability under land management alternatives from an environmental 

impact statement. Forest Ecology and Management. 153: 29–42.

Marcot, B.G.; Murphy, D.D. 1996. On population viability analysis and 

management. In: Szaro, R.C.; Johnson, D.W., eds. Biodiversity in managed 

landscapes: theory and practice. New York: Oxford University Press: 58–76.

Marcot, B.G.; Steventon, J.D.; Sutherland, G.D.; McCann, R.K. 2006b.

Guidelines for developing and updating Baysian belief networks for ecological 

modeling. Canadian Journal of Forest Research. 36: 3063–3074.

Marsh, D.M.; Milam, G.S.; Gorham, N.P.; Beckman, N.G. 2005. Forest roads as 

partial barriers to terrestrial salamander movement. Conservation Biology. 19(6): 

2004–2008.

Martin, J.W. 1987. Behavior and habitat use of breeding northern harriers in 

southwestern Idaho. Journal of Raptor Research. 21: 57–66.

Martin, J.; McIntyre, C.L.; Hines, J.E.; Nichols, J.D.; Schmutz, J.A.; 

MacCluskie, M.C. 2009. Dynamic multistate site occupancy models to evaluate 

hypotheses relevant to conservation of golden eagles in Denali National Park, 

Alaska. Biological Conservation. 142: 2726–2731.

Martin, J.W.; Parrish, J.R. 2000. Lark sparrow (Chondestes grammacus). In: 

Poole, A.; Gill, F., eds. The birds of North America, No. 488. Philadelphia, PA: 

The Birds of North America, Inc. 

Martin, S.K. 1987. The ecology of the pine marten (Martes americana) at

Sagehen Creek, California. Berkeley, CA: University of California. 223 p. 

Ph.D. dissertation. 

Martin, S.K.; Barrett, R.H. 1991. Resting site selection by marten at Sagehen 

Creek, California. Northwest Naturalist. 72: 37–42.

Marzluff, J.M.; Knick, S.T.; Vekasy, M.S.; Schueck, L.S.; Zarriello, T.J. 1997.

Spatial use and habitat selection of golden eagles in southwestern Idaho. Auk. 

114: 673–687.

Master, L.L. 1991. Assessing threats and setting priorities for conservation. 

Conservation Biology. 5: 559–563.
287

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Master, L.L.; Stein, B.A.; Kutner, L.S.; Hammerson, G.A. 2000. Vanishing 

assets: conservation status of US species. In: Stein, B.A.; Kutner, L.S.; Adams, 

J.S., eds. Precious heritage: the status of biodiversity in the United States. New 

York, NY: Oxford University Press: 93–118.

Mazurek, M.J. 2004. A maternity roost of Townsend’s big-eared bats 

(Corynorhinus townsendii) in coast redwood basal hollows in northwestern 

California. Northwestern Naturalist. 85: 60–62.

McAdoo, J.K.; Longland, W.S.; Evans, R.A. 1989. Nongame bird community 

responses to sagebrush invasion of crested wheatgrass seedlings. Journal of 

Wildlife Management. 53: 489–502.

McAllister, K.R.; Leonard, W.P. 1997. Washington state status report for the 

Oregon spotted frog. Olympia, WA: Washington Department of Fish and 

Wildlife. 47 p. 

McClelland, B.R. 1977. Relationships between hole-nesting birds, forest snags, 

and decay in western larch-Douglas-fir forests of the northern Rocky Mountains. 

Missoula, MO: University of Montana. 498 p. Ph.D. dissertation. 

McClelland, B.R. 1979. The pileated woodpecker in forests of the northern Rocky 

Mountians. In: Dickson, J.G.; Conner, R.N.; Fleet, R.R.; Jackson, J.A.; Kroll, 

J.C., eds. The role of insectivorous birds in forest ecosystems. New York, NY: 

Academic Press: 283–299.

McCord, C.M.; Cardoza, J.E. 1982. Bobcat and lynx. In: Chapman, J.A.; 

Feldhammer, G.A., eds. Wild mammals of North America. Baltimore, MD: 

Johns Hopkins University Press: 728–766.

McGahan, J. 1968. Ecology of the golden eagle. Auk. 85: 1–12.

McGarigal, K.; Anthony, R.G.; Isaacs, F.B. 1991. Interactions of humans and 

bald eagles on the Columbia River Estuary. Wildlife Monographs. 115: 1–47.

McGrady, M.J.; Grant, J.R.; Bainbridge, I.P.; McLeod, D.R.A. 2002. A model 

of golden eagle ranging behavior. Journal of Raptor Research. 36(supplement): 

62–69.

McGrath, M.T.; DeStefano, S.; Riggs, R.; Irwin, L.L.; Roloff, G.J. 2003.

Spatially explicit influences on northern goshawk nesting habitat in the interior 

Pacific Northwest. Wildlife Monograph No. 154: 1–63.
288

GENERAL TECHNICAL REPORT PNW-GTR-907

McIntyre, C.L.; Collopy, M.W.; Kidd, J.G.; Stickney, A.A.; Paynter, J. 2006.

Characteristics of the landscape surrounding golden eagle nest sites in Denali 

National Park and Preserve, Alaska. Journal of Raptor Research. 40: 46–51.

McIntyre, K.K. 2002. Species composition and beta diversity of avian 

communities in burned, mixed, and unburned sagebrush steppe habitat at 

Sheldon National Wildlife Refuge, Nevada. Alpine, TX: Sul Ross University. 

M.S. thesis. 

McKelvey, K.S.; Aubry, K.B.; Ortega, Y.K. 2000. History and distribution of 

lynx in the contiguous United States. In: Ruggerio, L.F.; Aubry, K.B.; Buskirk, 

S.W.; Koehler, G.M.; Krebs, C.J.; McKelvey, K.S.; Squires, J.R., eds. Ecology 

and conservation of lynx in the United States. Denver, CO: University Press of 

Colorado: 207–264.

McKibben, L.A.; Hofmann, P. 1985. Breeding range and populations studies 

of common snipe in California. California Fish and Game. 71: 68–75.

McLeod, D.R.; Whitfield, A.D.P.; McGrady, M.J. 2002. Improving prediction 

of golden eagle (Aquila chrysaetos) ranging in western Scotland, using GIS and 

terrain modelling. Journal of Raptor Research. 36(supplement): 72–79.

Medin, D.E.; Clary, W.B. 1991. Breeding bird populations in a grazed and 

ungrazed riparian habitat in Nevada. Res. Pap. INT-441. Ogden, UT: U.S. 

Department of Agriculture, Forest Service, Intermountain Research Station. 4 p.

Mellen-McLean, K.; Marcot, B.G.; Ohmann, J.L; Waddell, K.; Livingston, 

S.A.; Willhite, B.A.; Hostetler, B.B.; Ogden, C.; Dreisbach, T. 2009. DecAID, 

the decayed wood advisor for managing snags, partially dead trees, and down 

wood for biodiversity in forests of Washington and Oregon. Version 2.1. U.S. 

Department of Agriculture, Forest Service, Pacific Northwest Region and Pacific 

Northwest Research Station; U.S. Department of the Interior, Fish and Wildlife 

Service, Oregon State Office; Portland, OR. http://wwwnotes.fs.fed.us:81/pnw/

DecAID/DecAID.nsf. (June 15, 2010). 

Mellen-McLean, K.; Wales, B.; Bresson, B. 2013. A conservation assessment for 

whiteheaded woodpecker (Picoides albolarvatus). Portland, OR. U.S. Department 

of Agriculture, Forest Service, Pacific Northwest Region and U.S. Department of 

the Interior, Bureau of Land Management, Oregon State Office. 48 p. 

Mellen, T.K. 1987. Home range and habitat use by pileated woodpeckers. 

Corvallis, OR: Oregon State University. 96 p. M.S. thesis. 
289

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Menkens, G.E.; Anderson, S.H. 1983. How selective are golden eagles when 

choosing a nest site? Colorado-Wyoming Academy of Sciences. 15: 55–56.

Meslow, E.C.; Wight, H.M. 1975. Avifauna and succession in Douglas-fir

forests of the Pacific Northwest. In: Smith, D.R., coord. Proceedings of the 

symposium on management of forest and range habitats for nongame birds. 

Gen. Tech. Rep. WO-1. Washington, DC: U.S. Department of Agriculture, 

Forest Service: 266–271.

Messmer, T.A. 1990. Influence of grazing treatments on nongame birds and 

vegetation structure in south central North Dakota. Fargo, ND: North Dakota 

State University. 164 p. Ph.D. dissertation. 

Meyer, S.W. 2003. Comparative use of Phragmites australis and other habitats by 

birds, amphibians, and small mammals at Long Point, Ontario. Ontario, Canada: 

University of Western Ontario. 127 p. M.S. thesis. 

Millar, C.I.; Woolfenden, W.B. 1999. The role of climate change in interpreting 

historical variability. Ecological Applications. 9(4): 1207–1216.

Millsap, B.A.; Gore, J.A.; Runder, D.E.; Cerulean, S.I. 1990. Setting priorities 

for the conservation of fish and wildlife species in Florida. Wildlife Monographs. 

111: 1–57.

Milne, K.A.; Hejl, S.J. 1989. Nest-site characteristics of white-headed 

woodpeckers. Journal of Wildlife Management. 53: 50–55.

Moen, R.; Burdett, C.L.; Niemi, G.J. 2008. Movement and habitat use of Canada 

lynx during denning in Minnesota. Journal of Wildlife Management. 72(7): 

1507–1513.

Molloy, J.; Davis, A. 1992. Setting priorities for conservation of New Zealand’s 

threatened plants and animals. Wellington, New Zealand: Department of 

Conservation. 26 p.

Monello, R.J.; Dennehy, J.J.; Murray, D.L.; Wirsing, A.J. 2006. Growth and 

behavioral responses of tadpoles of two native frogs to an exotic competitor, 

Rana catesbeiana. Journal of Herpetology. 40: 403–407.

Monello, R.J.; Wright, R.G. 1999. Amphibian habitat preferences among artificial 

ponds in the Palouse region of northern Idaho. Journal of Herpetology. 33: 

298–303.
290

GENERAL TECHNICAL REPORT PNW-GTR-907

Morneau, F.; Brodeur, S.; Decarie, R.; Carriere, S.; Bird, D.M. 1994.

Abundance and distribution of nesting golden eagles in Hudson Bay, Quebec. 

Journal of Raptor Research. 28: 220–225.

Morris, R.L.; Tanner, W.W. 1969. The ecology of the western spotted frog, Rana 

pretiosa pretiosa Baird and Girard, a life history study. Great Basin Naturalist. 

29: 45–81.

Morrison, M.L. 1981. The structure of western warbler assemblages: analysis of 

foraging behavior and habitat selection in Oregon. Auk. 98: 578–588. 

Morrison, M.L.; Meslow, E.C. 1983. Bird community structure on early growth 

clear cuts in western Oregon. American Midland Naturalist. 110: 129–137. 

Morgan, P.L.; Aplet, G.H.; Haufler, J.B.; Humphries, H.C.; Moore, M.M.; 

Wilson, W.D. 1994. Historical range of variability: a useful tool for evaluating 

ecosystem change. In: Sampson, R.N.; Adams, D.L., eds. Assessing forest 

ecosystem health in the inland West. New York: Hawthorn Press: 87–111.

Mosconi, D.L.; Hutto, R.L. 1982. The effects of grazing on land birds of a western 

Montana riparian habitat. In: Wildlife-livestock relationships symposium. Peek, 

J.M.; Dalke, P.D., eds. University of Idaho, Forest and Range Experimental 

Station. Moscow, ID: 221–223

Mosher, J.A.; White, C.M. 1976. Directional exposure of golden eagle nests. 

Canadian Field-Naturalist. 90: 356–359.

Mowat, G.; Poole, K.G.; O’ Donoghue, M. 1999. Ecology of lynx in northern 

Canada and Alaska. In: Ruggerio, L.F.; Aubry, K.B.; Buskirk, S.W.; Koehler, 

G.M.; Krebs, C.J.; McKelvey, K.S.; Squires, J.R. Ecology and conservation of 

lynx in the United States. Gen. Tech. Rep. RMRS-GTR-30WWW. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station: 265–306.

Mueller, H. 1999. Wilson’s snipe (Gallinago delicata). In: Poole, A.; Gill, F., eds. 

The birds of North America, No. 417. Philadelphia, PA: The Birds of North 

America, Inc. 

Munger, J.C.; Garber, M.; Madrid, K.; Carroll, M.; Peterson, W.; Heberger, 

L. 1998. U.S. national wetland inventory classifications as predictors of the 

occurrence of Columbia spotted frogs (Rana luteiventris) and Pacific treefrogs 

(Hyla regilla). Conservation Biology. 12: 320–330.
291

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Muradian, R. 2001. Ecological thresholds: a survey. Ecological Economics. 

38: 7–24.

Murphy, E.C.; Lehnhausen, W.A. 1998. Density and foraging ecology of 

woodpeckes following a stand-replacement fire. Journal of Wildlife Management. 

62:4: 1359–1372.

Myers, L. 1991. Managing livestock to minimize impacts on riparian areas. In: 

Roth, R.; Bridges, C.; Zimmerman, C., eds. Riparian: What does it mean to me? 

Pueblo, CO: Third annual Colorado Riparian Association Conference: 24–30.

Nagorsen, D.W.; Brigham, R.M. 1993. Bats of British Columbia. Vancouver, WA: 

University of British Columbia Press. 164 p.

Nams, V.O.; Bourgeois, M. 2004. Fractal dimension measures habitat use at 

different spatial scales: an example with marten. Canadian Journal of Zoology. 

82: 1738–1747.

Nappi, A.; Drapeau, P.; Giroux, J.; Savard, J.L. 2003. Snag use by foraging 

blackbacked woodpeckers (Picoides arcticus) in a recently burned eastern boreal 

forest. Auk. 120: 505–511.

National Forest Management Act of 1976 [NFMA]; Act of October 22, 1976; 

16 U.S.C. 1600.

NatureServe. 2009. NatureServe Explore: an online encyclopedia of life [web 

application]. Version 7.1. NatureServe, Arlington, VA: U.S.A. http://www. 

natureserve.org/explorer. (19 January 2010).

Naugle, D.E.; Higgins, K.F.; Nusser, S.M. 1999. Effects of woody vegetation on 

prairie wetland birds. Canadian Field-Naturalist. 113: 487–492.

Naugle, D.E.; Johnson, R.; Estey, M.; Higgins, K. 2001. A landscape approach 

to conserving wetland bird habitat in the Prairie Pothole Region of eastern South 

Dakota. Wetlands. 21: 1–17.

Nauman, R.S.; Olson, D.H. 1999. Survey and manage salamander known sites. 

In: Olson, D.H., ed. Survey protocols for amphibians under the survey and 

manage provision of the Northwest Forest Plan. Version 3.0. Interagency Special 

Status and Sensitive Species Program. Portland, OR: U.S. Department of 

Agriculture, Forest Service and U.S. Department of the Interior, Bureau of Land 

Management: 43–78.

Nelson, S.K. 1988. Habitat use and densities of cavity nesting birds in the Oregon 

Coast Ranges. Corvallis, OR: Oregon State University. 157 p. M.S. thesis. 
292

GENERAL TECHNICAL REPORT PNW-GTR-907

Newman, G.A. 1970. Cowbird parasitism and nesting success of lark sparrows in 

southern Oklahoma. Wilson Bulletin. 82: 304–309.

Noon, B.R. 2003. Principles of ecosystem monitoring design. In: Busch, D.E.; 

Trexler, J.C., eds. Monitoring ecosystems: interdisciplinary approaches for 

evaluating ecoregional initiatives. Washington, DC: Island Press: 27–72. Chapter 

Nordstrom, N.; Milner, R. 1997. Larch mountain salamander, Plethodon larselli. 

In: Larson, E.M., tech. ed. Management recommendations for Washington’s 

priority species. Volume III: Amphibians and reptiles. Olympia, WA: 

Washington Department of Fish and Wildlife: 3-1–3-8.

Noss, R.F. 1990. Indicators for monitoring biodiversity: a hierarchial approach. 

Conservation Biology. 4(4): 355–364.

Noss, R.F.; O’Connell, M.A.; Murphy, D.D. 1997. The science of conservation 

planning: habitat conservation under the Endangered Species Act. Washington, 

DC: Island Press. 246 p.

Nussbaum, R.A.; Brodie, E.D.; Storm, R.M. 1983. Amphibians and reptiles of 

the Pacific Northwest. Moscow, ID: University of Idaho Press. 332 p.

Nyberg, J.B.; Marcot, B.G.; Sulyma, R. 2006. Using Bayesian belief networks in 

adaptive management. Canadian Journal of Forest Research. 36: 1–13.

Ogden, J.C.; Davis, S.M.; Brandt, L.A. 2003. Science strategy for a regional 

ecosystem monitoring and assessment program: The Florida Everglades 

examples. In: Busch, D.E.; Trexler, J.C., eds. Monitoring ecosystems: 

interdisciplinary approaches for evaluating ecoregional initiatives. Washington, 

DC: Island Press: 135–166.

Ohmann, J.L.; Gregory, M.J. 2002. Predictive mapping of forest composition 

and structure with direct gradient analysis and nearest neighbor imputation in 

the coastal province of Oregon, U.S.A. Canadian Journal of Forest Research. 32: 

725–741.

Olechnowski, B.F.M.; Debinski, D.M . 2008. Response of songbirds to riparian 

willow habitat structure across two regions of the Greater Yellowstone 

Ecosystem. Wilson Journal of Ornithology. 120: 830–839.

Olendorff, R.R. 1976. The food habits of North American golden eagles. American 

Midland Naturalist. 95: 231–236.
293

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Olson, G.S.; Glenn, E.M.; Anthony, R.G.; Forsman, E.D.; Reid, J.A.; 

Loschl, P.J.; William, J.R. 2004. Modeling demographic performance of 

northern spotted owls relative to forest habitat in Oregon. Journal of Wildlife 

Management. 68(4): 1039–1053.

Oregon Department of Fish and Wildlife. 2005. Oregon Conservation Strategy. 

Salem, OR. 

Organ, J.F.; Vashon, J.H.; McDonald, J.E., Jr.; Vashon, A.D.; Crowley, S.M.; 

Jakubas, W.J.; Matula, G.J., Jr.; Meehan, A.L. 2008. Within-stand selection 

of Canada lynx natal dens in northwest Maine, USA. Journal of Wildlife 

Management. 72(7): 1514–1517.

Ozesmi, S.L.; Ozesmi, U. 1999. An artificial neural network approach to spatial 

habitat modelling with interspecific interaction. Ecological Modelling. 116: 

15–31.

Page, J.L.; Dodd, N.; Osborne, T.O.; Carson, J.A. 1978. The influence of 

livestock grazing on non-game wildlife. California Nevada Wildlife: 159–173.

Papouchis, C.M.; Singer, F.J.; Sloan, W.B. 2001. Responses of desert bighorn 

sheep to increased human recreation. Journal of Wildlife Management. 65(3): 

573–582.

Patla, S.M. 1997. Nesting ecology and habitat of the northern goshawk in 

undisturbed and timber harvest areas on the Targhee National Forest, Greater 

Yellowstone Ecosystem. Pocatello, ID: Idaho State University. 164 p. M.S. thesis. 

Patriquin, K.J.; Barclay, R.M.R. 2003. Foraging by bats in cleared, thinned and 

unharvested boreal forest. Journal of Applied Ecology. 40: 646–657.

Payer, R.D.; Harrison, D.J. 1999. Effects of forest structure on spatial distribution 

of American marten. Tech. Bull. 787. Research Triangle Park, NC: National 

Council of the Paper Industry for Air and Stream Improvement. 37 p.

Pearl, C.A.; Adams, M.J.; Wente, W.H. 2007. Characteristics of Columbia 

spotted frog (Rana luteiventris) oviposition sites in northeastern Oregon, USA. 

Western North American Naturalist. 67: 86–91.

Pearl, C.A.; Bull, E.L.; Green, D.E.; Bowerman, J.; Adams, M.J.; Hyatt, A.; 

Wente, W.H. 2007. Occurrence of the amphibian pathogen Batrachochytrium 

dendrobatidis in the Pacific Northwest. Journal of Herpetology. 41: 145–149.
294

GENERAL TECHNICAL REPORT PNW-GTR-907

Pedrini, P.; Sergio, F. 2002. Regional conservation priorities for a large predator: 

golden eagles (Aquila chrysaetos) in the alpine range. Biological Conservation. 

103: 163–172.

Perry, D.A.; Hessburg, P.E.; Skinner, C.N.; Spies, T.A.; Stephens, S.L.; Henry 

Taylor, A.; Franklin, J.F.; McComb, B.; Riegel, G. 2011. The ecology of 

mixed severity fire regimes in Washington, Oregon, and northern California. 

Forest Ecology and Management. 262: 703–717.

Peters, D.D. 1990. Wetlands and deep water habitats in the state of Washington. 

Olympia, WA: U.S. National Wetlands Inventory, Fish and Wildlife Service. 6 p.

Peterson, B.; Gauthier, G. 1985. Nest site use by cavity-nesting birds of Cariboo 

Parkland, British Columbia. Wilson Bulletin. 97: 319–331.

Petersen, K.L.; Best, L.B. 1987. Effects of prescribed burning on nongame birds 

in a sagebrush community. Wildlife Society Bulletin. 15: 317–329.

Peterson, K.L.; Best, L.B. 1999. Design and duration of perturbation experiments: 

implications for data interpretation. Studies in Avian Biology. 19: 230–236.

Phillips, R.L.; Beske, A.E. 1990. Distribution and abundance of golden eagles 

and other raptors in Campbell and Converse Counties, Wyoming. Tech. Rep. 27. 

Washington, DC: U.S. Fish and Wildlife Service. 

Phillips, R.L.; McEneaney, T.P.; Beske, A.E. 1984. Population densities of 

breeding golden eagles in Wyoming. Wildlife Society Bulletin. 12: 269–273.

Phillips, R.L.; Wheeler, A.H.; Lockhart, J.M.; McEneaney, T.P.; Forrester, 

N.C. 1990. Nesting ecology of golden eagles and other raptors in southeastern 

Montana and northern Wyoming. Tech. Rep. 26. Washington, DC: U.S. Fish and 

Wildlife Service. 

Picman, J.; Milks, M.L.; Leptich, M. 1993. Patterns of predation on passerine 

nests in marshes: effects of water depth and distance from edge. Auk. 110: 

89–94.

Pierson, E.D.; Rainey, W.E. 1998. Distribution, status, and management of 

Townsend’s big-eared bat (Corynorhinus townsendii) in California. Technical 

Report 96-7. Davis, CA: Birds and Mammals Conservation Program, California 

Department of Fish and Game. 

Pilliod, D.S.; Peterson, C.R. 2001. Local and landscape effects of introduced trout 

on amphibians in historically fishless watersheds. Ecosystems. 4: 322–333.
295

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Pilliod, D.S.; Peterson, C.R.; Ritson, P.I. 2002. Seasonal migration of Columbia 

spotted frogs (Rana luteiventris) among complementary resources in a high 

mountain basin. Canadian Journal of Zoology. 80: 1849–1862.

Piper, S.D. 1996. Terrestrial amphibian and passerine bird abundance in riparian 

habitats of eastern Washington Cascade Forests. Pullman, WA: Washington State 

University. 131 p. M.S. thesis.

Pitocchelli, J. 1995. MacGillivray’s warbler (Oporornis tolmiei). In: Poole, A.; Gill, 

F., eds. The birds of North America. No. 159. Philadelphia, PA: The Academy of 

Natural Sciences; Washington, DC: The American Ornithologists’ Union. 

Potvin, F.; Belanger, L.; Lowell, K. 2000. Marten habitat selection in a clearcut 

boreal landscape. Conservation Biology. 14: 844–857.

Prescott, D.R.C. 1997. Avian communities and NAWMP habitat priorities in 

the northern prairie biome of Alberta. NAWMP-029. St. Albert, AB: Land 

Stewardship Centre of Canada. 41 p.

Prescott, D.R.C.; Murphy, A.J.; Ewaschuk, E. 1995. An avian community 

approach to determining biodiversity values of NAWMP habitats in the aspen 

parkland of Alberta. NAWMP-012. Edmonton, AB: Alberta NAWMP Centre. 

58 p.

Rabe, M.J.; Morrell, T.E.; Green, H.; DeVos, J.C., Jr.; Miller, C.R. 1998.

Characteristics of ponderosa pine snag roosts used by reproductive bats in 

northern Arizona. Journal of Wildlife Management. 62: 612–621.

Radford, J.Q.; Bennett, A.F.; Cheers, J.G. 2005. Landscape-level thresholds 

of habitat cover for woodland-dependent birds. Biological Conservation. 124: 

317–337.

Raesly, R.L.; Gates, J.E. 1987. Winter habitat selection by north temperate cave 

bats. American Midland Naturalist. 118: 15–31.

Rancourt, S.J.; Rule, M.I.; O’Connell, M.A. 2008. Maternity roost site selection 

of big brown bats in ponderosa pine forests of the Channeled Scablands of 

northeastern Washington state, USA. Forest Ecology and Management. 248: 

183–192.

Randall-Parker, T.; Miller, R. 2002. Effects of prescribed fire in ponderosa 

pine on key wildlife habitat components: preliminary results and a method for 

monitoring. Gen. Tech. Rep. PSW-GTR-181. Albany, CA: U.S. Department of 

Agriculture, Forest Service, Pacific Southwest Research Station: 823–834. 
296

GENERAL TECHNICAL REPORT PNW-GTR-907

Raphael, M.G. 1981. Interspecific differences in nesting habitat of sympatric 

woodpeckers and nuthatches. In: Capen, D.E., ed. The use of multivariate 

statistics in studies of wildlife habitat. Gen. Tech. Rep. RM-87. Albany, CA: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Forest and Range 

Experimental Station: 142–151.

Raphael, M.G.; Marcot, B.G. 1994. Key questions and issues-species and 

ecosystem viability. Journal of Forestry. 92: 45–47.

Raphael, M.G.; Morrison, M.L.; Yoder-Williams, M.P. 1987. Breeding bird 

populations during twenty-five years of postfire succession in the Sierra Nevada. 

Condor. 89: 614–626.

Raphael, M.G.; White, M. 1984. Use of snags by cavity-nesting birds in the Sierra 

Nevada. Wildlife Monograph No. 86: 1–66.

Raphael, M.G.; Wisdom, M.J.; Rowland, M.M.; Holthausen, R.S.; Wales, 

B.C.; Marcot, B.G.; Rich, T.D. 2001. Status and trends of habitats of terrestrial 

vertebrates in relation to land management in the interior Columbia river basin. 

Forest Ecology and Management. 153: 63–88.

Ratcliffe, D.A. 1993. The peregrine falcon. 2nd ed. London, England: T and A D 

Poyser. 454 p.

Rawinski, T.J.; Malecki, R.A. 1984. Ecological relationships among purple 

loosestrife, cattail, and wildlife at the Montezuma National Wildlife Refuge. 

New York Fish and Game Journal. 31: 81–87.

Reaser, J.K. 2000. Demographic analysis of the Columbia spotted frog (Rana 

luteiventris): case study in spatio-temporal variation. Canadian Journal of 

Zoology. 78: 1158–1167.

Reaser, J.K.; Pilliod, D.S. 2005. Rana luteiventris Thompson 1913, Columbia 

spotted frog. In: Lannoo, M., ed. Amphibian declines: the conservation status of 

United States species. Berkeley, CA: University of California Press: 559–563.

Reichel, J.D.; Beckstrom, S.G. 1994. Northern bog lemming survey. Helena, MO: 

Montana Natural Heritage Program. 87 p.

Reinkensmeyer, D.P.; Miller, R.F.; Anthony, R.G.; Marr, V.E. 2007. Avian 

community structure along a mountain big sagebrush successional gradient. 

Journal of Wildlife Management. 71: 1057–1066.

Renwald, J.D. 1977. Effect of fire on lark sparrow nesting densities. Journal of 

Range Management. 30: 283–285.
297

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Reynolds, R.T.; Graham, R.T.; Reiser, M.H.; Bassett, R.L.; Kennedy, P.L.; 

Boyce, D.A.; Goodwin, G.; Smith, R.; Fisher, E.L. 1992. Management 

recommendations for the northern goshawk in the southwestern United 

States. Gen. Tech. Rep. GTR-RM-217. Fort Collins, CO: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 90 p.

Reynolds, T.D.; Rich, T.D.; Stephens, D.A. 1999. Sage thrasher (Oreoscoptes 

montanus). Number 463. In: Poole, A.; Gill, F., eds. The birds of North America. 

Philadelphia, PA: The Academy of Natural Sciences; Washington, DC: The 

American Ornithologists’ Union. 

Reynolds, T.D.; Trost, C.H. 1980. The response of native vertebrate populations 

to crested wheatgrass planting and grazing by sheep. Journal of Range 

Management. 33: 122–125.

Reynolds, T.D.; Trost, C.H. 1981. Grazing, crested wheatgrass and bird 

populations in southeastern Idaho. Northwest Science. 55: 225–234.

Richardson, C.T.; Miller, C.K. 1997. Recommendations for protecting raptors 

from human disturbance: a review. Wildlife Society Bulletin. 25: 634–638.

Richter, W. 1984. Nestling survival and growth in the yellow-headed blackbird, 

Xanthocephalus xanthocephalus. Ecology. 65: 597–608.

Rieman, B.; Peterson, J.T.; Clayton, J; Howell, P.; Thurow, R.; Thompson, 

W.; Lee, D. 2001. Evaluation of potential effects of federal land management 

alternatives on trends of salmonids and their habitats in the interior Columbia 

River basin. Forest Ecology and Management. 153: 43–62.

Robb, J.R.; Bookhout, T.A. 1995. Factors influencing wood duck use of natural 

cavities. Journal of Wildlife Management. 59: 372–383.

Roberge, J.; Angelstam, P. 2004. Usefulness of the umbrella species concept as a 

conservation tool. Conservation Biology. 18: 76–85.

Roberts, J.; Chick, A.; Oswald, L.; Thompson, P. 1995. Effect of carp, Cyprinus 

carpio L., an exotic benthivorous fish, on aquatic plants and water quality in 

experimental ponds. Marine and Freshwater Research. 46: 1171–1180.

Rodrick, E.A. 1986. Survey of historic habitats of the western gray squirrel 

(Sciurus griseus) in the southern Puget Trough and Klickitat County, 

Washington. Seattle, WA: University of Washington. 41 p. M.S. thesis.

Rogers J.A., Jr.; Smith, H.T. 1995. Set-back distances to protect nesting bird 

colonies from human disturbance in Florida. Conservation Biology. 9: 89–99.
298

GENERAL TECHNICAL REPORT PNW-GTR-907

Rompre, G.; Boucher, Y.; Belanger, L.; Cote, S.; Robinson, W.D. 2010.

Conserving biodiverisity in managed forest landscapes: the use of critical 

thresholds for habitat. Forestry Chronicle. 86(5): 589–596.

Rose, C.; Marcot, B.; Mellen, T.K.; Ohmann, J.L.; Waddell, K.; Lindley, D.; 

Schreiber, B. 2001. Decaying wood in Pacific Northwest forests: concepts and 

tools for habitat management. In: Johnson, D.; O’Neal, T., eds. Wildlife-habitat 

relationships in Oregon and Washington. Corvallis, OR: Oregon State Unversity 

Press: 580–623.

Rosenstock, S.S. 1996. Habitat relationships of breeding birds in northern Arizona 

ponderosa pine and pine-oak forests. Tech. Rep. 23. Arizona Game and Fish 

Department. 

Ross, A. 1967. Ecological aspects of the food habits of insectivorous bats. Western 

Foundation of Vertebrate Zoology. 1: 205–264.

Ross, D.; Reaser, J.K.; Kleeman, P.; Drake, D.L. 1999. Rana luteiventris

(Columbia spotted frog) mortality and site fidelity. Herpetological Review.

30: 163.

Rowland, M.M.; Wisdom, M.J.; Johnson, D.H.; Wales, B.C.; Copeland, J.P.; 

Edelmann, F.B. 2003. Evaluation of landscape models for wolverines in the 

interior Northwest, United States of America. Journal of Mammalogy. 84(1): 

92–105.

Ruediger, B.; Claar, J.; Gniadek, S. [et al.]. 2000. Canada lynx conservation 

assessment and strategy. Publ. R1-00-53. Missoula, MT: U.S. Department of 

Agriculture, Forest Service; U.S. Department of the Interior, Fish and Wildlife 

Service, Bureau of Land Management, National Park Service. 142 p.

Ruggiero, L.F.; Aubry, K.B.; Buskirk, S.W.; Lyon, L.J.; Zielinski, W.J. 1994.

The scientific basis for conserving forest carnivores: American marten, fisher, 

lynx and wolverine in the Western United States. Gen. Tech. Rep. GTR-RM-254. 

Fort Collins, CO: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station. 184 p.

Ruggerio, L.F.; McKelvey, K.S.; Aubry, K.B.; Copeland, J.P.; Pletscher, D.H.; 

Hornocker, M.G. 2007. Wolverine conservation and management. Journal of 

Wildlife Management. 71(7): 2145–2146.

Ruggiero, L.F.; Pearson, D.E.; Henry, S.E. 1998. Characteristics of American 

marten den sites in Wyoming. Journal of Wildlife Management. 62: 663–673.
299

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Russell, R.E.; Saab, V.A.; Dudley, J.G. 2007. Habitat-suitability models for 

cavity-nesting birds in a postfire landscape. Journal of Wildlife Management. 

71(8): 2600–2611.

Ryan, L.A.; Carey, A.B. 1995. Biology and management of the western gray 

squirrel and Oregon white oak woodlands: with emphasis on the Puget Trough. 

Gen. Tech. Rep. PNW-GTR-348. Portland, OR: U.S.Department of Agricullture, 

Forest Service, Pacific Northwest Research Station. 36 p.

Saab, V.A.; Bock, C.E.; Rich, T.D.G.; Dobkin, D.S. 1995. Livestock grazing 

effects in western North America. In: Martin, T.E.; Finch, D.M., eds. Ecology 

and management of Neotropical migratory birds: a synthesis and review of 

critical issues. New York, NY: Oxford University Press: 311–353.

Saab, V.A.; Dudley, J. 1998. Responses of cavity-nesting birds to standreplacement fire and salvage logging in ponderosa pine/Douglas-fir forests of 

southwestern Idaho. Res. Pap. RMRS-RP-11. Ogden, UT: U.S. Department of 

Agriculture, Forest Service, Rocky Mountain Research Station. 17 p.

Saab, V.A.; Powell, H.D.W.; Kotliar, N.B.; Newlon, K.R. 2005. Variation in fire 

regimes of the Rocky Mountains: implications for avian communities and fire 

management. Studies in Avian Biology. 30: 76–96.

Saab, V.A.; Russell, R.E.; Dudley, J.G. 2009. Nest-site selection by cavity-nesting 

birds in relation to postfire salvage logging. Forest Ecology and Management. 

257: 151–159.

Saab, V.A.; Vierling, K.T. 2001. Reproductive success of Lewis’s woodpecker in 

burned pine and cottonwood riparian forests. Condor. 103: 491–501.

Salafsky, S.R.; Reynolds, R.T. 2005. Patterns of temporal variation in goshawk 

reproduction and prey resources. Journal of Raptor Research. 39(3): 237–246.

Sallabanks, R. 1995. Avian biodiversity and bird-habitat relationships in conifer 

forest of the inland Northwest: an ecosystem management approach. Annual rep. 

to Boise Cascade Corp. Meridian, ID: National Fish and Wildlife Foundation, 

National Council for Air and Stream Improvement and U.S. Department of 

Agriculture, Forest Service, Sustainable Ecosystems Institute. 

Sallabanks, R.; Marcot, B.G.; Riggs, R.A.; Mehl, C.A.; Arnett, E.B. 2001.

Wildlife of eastside (interior) forests and woodlands. In: Johnson, D.H.; O’Neil, 

T.A., eds. Wildlife-habitat relationships in Oregon and Washington. Corvallis, 

OR: Oregon State University Press: 213–238.
300

GENERAL TECHNICAL REPORT PNW-GTR-907

Sample, B.E. 1991. Effects of Dimilin on food of the endangered Virginia bigeared bat. Morgantown, WV: West Virginia University. 201 p. Ph.D. dissertation. 

Samson, F.B. 2002. Population viability analysis, management, and conservation 

planning at large scales. In: Beissinger, S.R.; McCullough, D.R., eds. Population 

viability analysis. Chicago, Il: University of Chicago Press: 425–441.

Samson, F.B.; Knopf, F.L.; McCarthy, C.W. [et al.]. 2003. Planning for 

population viability on Northern Great Plains national grasslands. Wildlife 

Society Bulletin. 31(4): 986–999.

Samuels, I.A.; Gardali, T.; Humple, D.L.; Geupel, G.R. 2005. Winter site 

fidelity and body condition of three riparian songbird species following a fire. 

Western North American Naturalist. 65: 45–52.

Sarell, M.J. 2004. Tiger salamander Ambystoma tigrinum. I: accounts and 

measures for managing identified wildlife—accounts V. Victoria, BC: British 

Columbia Ministry of Water, Land and Air Protection. 9 p.

Saunders, A.A. 1913. A study of the nesting of the marsh hawk. Condor. 15: 

99–104.

Savard, J.-P.L.; Boyd, W.S.; Smith, G.E.J. 1994. Waterfowl-wetland relationships 

in the aspen parkland of British Columbia: comparison of analytical methods. 

Hydrobiologia. 279/280: 309–325.

Schirato, G. 1994. Population and distribution of harlequin ducks in Washington 

state. In: Galiano, B.C., ed. Proceeding of the second harlequin duck symposium. 

Harlequin Duck Working Group: 18.

Schmalzried, J.T. 1976. Nesting and food habits of the golden eagle on the 

Laramie Plains. Laramie, WY: University of Wyoming. 86 p. M.S. thesis. 

Schmid, W.D. 1972. Snowmobile activity, subnivean microclimate and winter 

mortality of small mammals. Proceedings of the American Institute of Biological 

Scientists. Bulletin of the Ecological Society of American. 53(2): 37.

Schommer, T.J.; Woolever, M.M. 2008. A review of disease related conflicts 

between domestic sheep and goats and bighorn sheep. Gen. Tech. Rep. RMRSGTR-209. Ogden, UT: U.S. Department of Agriculture, Forest Service, Rocky 

Mountain Research Station. 16.

Schulz, T.T.; Leininger, W.C. 1991. Non-game wildlife communities in grazed 

and ungrazed Montana riparian sites. Great Basin Naturalist. 51: 286–292.
301

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Schwab, F.E.; Simon, N.P.; Sinclair, A.R. 2006. Bird-vegetation relationships in 

Southeastern British Columbia. Journal of Wildlife Management. 70(1): 189–197. 

Scott, T.A. 1985. Human impacts on the golden eagle population of San Diego 

County. San Diego, CA: San Diego State University. 202 p. M.S. thesis. 

Scott, V.E.; Evans, K.E.; Patton, D.R.; Stone, C.P. 1977. Cavity-nesting birds of 

North American forests. Agric. Handb. 511. Washington, DC: U.S. Department 

of Agriculture. 112 p.

Sealy, S.G. 1967. Notes on the breeding biology of the marsh hawk in Alberta and 

Saskatchewan. Blue Jay. 25: 63–69.

Sedivec, K.K. 1994. Grazing treatment effects on and habitat use of upland nesting 

birds on native rangeland. Fargo, ND: North Dakota State University. 124 p. 

Ph.D. dissertation.

Semlitsch, R.D. 1998. Biological delineation of terrestrial buffer zones for pondbreeding salamanders. Conservation Biology. 12: 1113−1119.

Sergio, F.; Pedrini, P.; Rizzolli, E.; Marchesi, L. 2006. Adaptive range selection 

by golden eagles in a changing landscape: a multiple modelling approach. 

Biological Conservation. 133: 32–41.

Serrentino, P. 1992. Northern harrier, Circus cyaneus. In: Schneider, K.J.; Pence, 

D.M., eds. Migratory nongame birds of management concern in the Northeast. 

Newton Corner, MA: U.S. Fish and Wildlife Service: 89–117.

Shaffer, J.A.; Goldade, C.M.; Dinkins, M.F.; Johnson, D.H.; Igl, L.D.; Euliss, 

B.R. 2003. Brown-headed cowbirds in grasslands: their habitats, hosts, and 

response to management. Prairie Naturalist. 35: 146–186.

Shaffer, M.L.; Stein, B.A. 2000. Safeguarding our precious heritage. In: Stein, 

B.A.; Kutner, L.S.; Adams, J.S., eds. Precious heritage: the status of biodiversity 

in the United States. New York: Oxford University Press: 301–321.

Simmons, R.; Smith, P.C. 1985. Do northern harriers (Circus cyaneus) choose nest 

sites adaptively? Canadian Journal of Zoology. 63: 494–498.

Simon, N.P.P.; Schwab, F.E.; Otto, R.D. 2002. Songbird abundance in clear-cut 

and burned stands: a comparison of natural disturbance and forest management. 

Canadian Journal of Forest Research. 32: 1343–1350.

Singer, F.J.; Moses, M.E.; Bellew, S.; Sloan, W. 2000. Correlates to colonizations 

of new patches by translocated populations of bighorn sheep. Restoration 

Ecology. 8(4S): 66–74.
302

GENERAL TECHNICAL REPORT PNW-GTR-907

Singleton, P.H.; Gaines, W.L.; Lehmkuhl, J.F. 2002. Landscape permeability 

for large carnivores in Washington: a geographic information system weighteddistance and least-cost corridor assessment. Gen. Tech. Rep. PNW-GTR-549. 

Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest 

Research Station. 13 p.

Singleton, P.H.; Lehmkuhl J.F. 1998. Wildlife and roadway interactions: a 

bibliography and review of roadway and wildlife interactions. Wenatchee, WA: 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Research 

Station. 162 p.

Singleton, P.H.; Lehmkuhl, J.F. 2000. I-90 Snoqualmie Pass wildlife habitat 

linkage assessment. Publ. No. WA-RD 489.1. Portland, OR: U.S. Department of 

Agriculture, Forest Service, Pacific Northwest Research Station. 106 p.

Singleton, P.H.; Lehmkuhl, J.F.; Gaines, W.L.; Graham, S.A. 2010. Barred owl 

space use and habitat selection in the eastern Cascades, Washington. Journal of 

Wildlife Management. 74(2): 285–294.

Skagen, S.K.; Knight, R.L.; Orians, G.H. 1991. Human disturbance of an avian 

scavenging guild. Ecological Applications. 1(2): 215–225.

Skagen S.K.; Melcher, C.P.; Muths, E. 2001. The interplay of habitat change, 

human disturbance and species interactions in a waterbird colony. American 

Midland Naturalist. 145: 18–28.

Slauson, K.M.; Zielinski, W.J. 2009. Characteristics of summer and fall diurnal 

resting habitat used by American martens in coastal northwestern California. 

Northwest Science. 83: 35–45.

Slauson, K.M.; Zielinski, W.J.; Hayes, J.P. 2007. Habitat selection by American 

martens in coastal California. Journal of Wildlife Management. 71: 458–468.

Slough, B.B. 1999. Characteristics of Canada lynx, lynx canadensis, maternal dens 

and denning habitat. Canadian Field-Naturalist. 113(4): 605–608.

Smith, D.G.; Murphy, J.R. 1979. Breeding responses of raptors to jackrabbit 

density in the eastern Great Basin Desert of Utah. Journal of Raptor Research. 

13: 1–14.

Smith, D.G.; Murphy, J.R. 1982. Spatial relationships of nesting golden eagles in 

central Utah. Journal of Raptor Research. 16: 127–132.

Smith, G.W.; Nydegger, N.C. 1985. A spotlight, line-transect method for 

surveying jack rabbits. Journal of Wildlife Management. 49: 699–702.
303

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Smith, M.R.; Mattocks, P.W., Jr.; Cassidy, K.M. 1997. Breeding birds of 

Washington state. Volume 4. In: Cassidy, K.M.; Grue, C.E.; Smith, M.R.; 

Dvornich, K.M., eds. Washington state gap analysis; final report. Audubon 

Society Publications in Zoology 1. Seattle, WA: Seattle Audubon Society. 146 p.

Smith, T.G. 2002. Small mammal relationships with downed wood and antelope 

bitterbrush in ponderosa pine forest of central Oregon. Corvallis, OR: Oregon 

State University. 146 p. M.S. thesis.

Smith, T.S.; Flinders, J.T.; Winn, D.S. 1991. A habitat evaluation procedure 

for Rocky Mountain bighorn sheep in the intermountain West. Great Basin 

Naturalist. 51: 205–225.

Smucker, K.M.; Hutto, R.L.; Steele, B.M. 2005. Changes in bird abundance after 

wildfire: importance of fire severity and time since fire. Ecological Applications. 

15(5): 1535–1549.

Snedecor, G.W.; Cochran, W.G. 1989. Statistical methods. 6th ed. Ames, IA: Iowa 

State University Press. 593 p.

Snyder, J.E.; Bissonette, J.A. 1987. Marten use of clear-cuttings and residual 

forest stands in western Newfoundland. Canadian Journal of Zoology. 65: 

169–174.

Society for Ecological Restoration. 1993. Mission statement, Society for 

Ecological Restoration. Restoration Ecology. 1: 206–207.

Soulliere, G. 1988. Density of suitable wood duck nest cavities in a northern 

hardwood forest. Journal of Wildlife Management. 52: 86–89.

Sousa, P.J.; Farmer, A.H. 1983. Habitat suitability index models: wood duck. 

FWS/OBS-82/10.43. Washington, DC: U.S. Department of the Interior, Fish and 

Wildlife Service. 38 p. 

Soutiere, E.C. 1979. Effects of timber harvesting on marten in Maine. Journal 

of Wildlife Management. 43: 850–860.

Spencer, W.D.; Barrett, R.H.; Zielinski, W.J. 1983. Marten habitat preferences 

in the northern Sierra Nevada. Journal of Wildlife Management. 47: 1181–1186.

Spring, L.W. 1965. Climbing and pecking adaptations in some North American 

woodpeckers. Condor. 67: 457–488.
304

GENERAL TECHNICAL REPORT PNW-GTR-907

Squires, J.R.; Decesare, N.J.; Kolbe, J.A.; Ruggiero, L.F. 2008. Hierarchical den 

selection of Canada lynx in western Montana. Journal of Wildlife Management. 

72(7): 1497–1506.

Squires, J.R.; Laurion, T. 2000. Lynx home range and movements in Montana 

and Wyoming: preliminary results. In: Ruggerio, L.F.; Aubry, K.B.; Buskirk, 

S.W.; Koehler, G.M.; McKelvey, K.S.; Squires, J.R. Ecology and conservation of 

lynx in the United States. Gen. Tech. Rep. RMRS-GTR-30WWW. Fort Collins, 

CO: U.S. Department of Agriculture, Forest Service, Rocky Mountain Research 

Station: 337–349.

Stalmaster, M.V. 1987. The bald eagle. New York, NY: Universe Books. 

Stalmaster, M.V.; Newman, J.R. 1978. Behavioral responses of wintering bald 

eagles to human activity. Journal of Wildlife Management. 42: 506–513.

Steen, D.A.; Gibbs, J.P.; Timmermans, S.T.A. 2006. Assessing the sensitivity 

of wetland bird communities to hydrologic change in the eastern Great Lakes 

region. Wetlands. 26: 605–611.

Steenhof, K.; Kochert, M.N.; Doremus, J.H. 1983. Nesting of subadult golden 

eagles in southwestern Idaho. Auk. 100: 743–747.

Steenhof, K.; Kochert, M.N.; McDonald, T.L. 1997. Interactive effects of prey 

and weather on golden eagle reproduction. Journal of Animal Ecology. 66: 

350–362.

Steenhof, K.; Kochert, M.N.; Roppe, J.A. 1993. Nesting by raptors and ravens on 

electrical transmission line towers. Journal of Wildlife Management. 57: 271–281

Steidl, R.J.; Kozie, K.D.; Dodge, G.J.; Pehovski, T.; Hogan, E.R. 1993. Effects 

of human activity on breeding behavior of golden eagles in Wrangell-St. Elias 

National Park and Preserve: a preliminary assessment. WRST Reserve Resource 

Management Report 93-3. Copper Center, AK: National Park Service, WrangellSt. Elias National Park.

Stewart, R.E. 1975. Breeding birds of North Dakota. Fargo, ND: Tri-College 

Center for Environmental Studies. 295 p.

Stewart, R.E.; Kantrud, H.A. 1965. Ecological studies of waterfowl populations 

in the prairie potholes of North Dakota. 1965 Progress Report. [Place of 

publication unknown]: U.S. Fish and Wildlife Service, Bureau of Sport Fisheries 

and Wildlife. 14 p.
305

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Stinson, D.W.; Watson, J.W.; McAllister, K.R. 2007. Washington state status 

report for the bald eagle. Olympia, WA: Washington Department of Fish and 

Wildlife. 86 p.

Stoddard, M.A.; Hayes, J.P. 2005. The influence of forest management on 

headwater stream amphibians at multiple spatial scales. Ecological Applications. 

15(3): 811–823.

Studier, E.H.; O’Farrell, M.J. 1980. Physiological ecology of Myotis. In: Wilson, 

D.E.; Gardner, A.L. eds. Proceedings of the fifth international bat research 

conference. Lubbock, TX: Texas Press: 415–423.

Suding, K.N.; Gross, K.L.; Houseman, G. 2004. Alternative states and positive 

feedbacks in restoration ecology. Trends in Ecology and Evolution. 19: 46–53.

Sullivan, S.L.; Pyle, W.H.; Herman, S.G. 1986. Cassin’s finch nesting in big 

sagebrush. Condor. 88: 378–379. 

Suring, L.H.; Gaines, W.L.; Wales, B.C.; Mellen-McLean, K.; Begley, J.S.; 

Mohoric, S. 2011. Maintaining populations of terrestrial wildlife through land 

management planning: a case study. Journal of Wildlife Management. 75(4): 

945–958.

Svancara, L.K.; Brannon, R.; Scott, J.M.; Groves, C.R.; Noss, R.F.; Pressey, 

R.L. 2005. Policy-driven versus evidence-based conservation: a review of 

political targets and biological needs. BioScience. 55(11): 989–995.

Swanson, F.J.; Jones, J.A.; Wallin, D.O.; Cissel, J.H. 1994. Natural variability—

implications for ecosystem management. In: Mensen, M.E.; Bourgeron, P.S., eds. 

Volume II: Ecosystem mangement: principles and applications. Gen. Tech. Rep. 

PNW-GTR-318. Portland, OR: U.S. Department of Agriculture, Forest Service, 

Pacific Northwest Research Station: 80–94.

Szaro, R.C. 1976. Population densities, habitat selection, and foliage use by the 

birds of selected ponderosa pine areas in the Beaver Creek Watershed, Arizona. 

Flagstaff, AZ: Northern Arizona University. 264 p. Ph.D. dissertation.

Taylor, D.M. 1986. Effects of cattle grazing on passerine bird nesting in riparian 

habitat. Journal of Range Management. 39: 254–258.

Tazik, D.J. 1991. Effects of army training activities on bird communities at 

the Pinon Canyon maneuver site, Colorado. USACERL Tech. Rep. N-91/31. 

Champaign, IL: U.S. Army Corps of Engineers, Construction Engineering 

Research Laboratory.
306

GENERAL TECHNICAL REPORT PNW-GTR-907

Tear, T.H.; Kareiva, P.; Angermeier, P.L. [et al.]. 2005. How much is enough? 

The recurrent problem of setting measurable objectives in conservation. 

BioScience. 55(10): 835–849.

Terres, J.K. 1980. The Audubon Society encyclopedia of North American birds. 

New York, NY: Alfred A. Knopf.

Tewksbury, J.J.; Martin, T.E.; Hejl, S.J.; Redman, T.S.; Wheeler, F.J. 1999.

Cowbirds in a western valley: effects of landscape structure, vegetation, and host 

density. Studies in Avian Biology. 18: 23–33.

Thelander, C.G. 1974. Nesting territory utilization by golden eagles (Aquila 

chrysaetos) in California during 1974. Special Wildlife Investigations. 

Sacramento, CA: California Department of Fish and Game. 

Thompson, I.D. 1994. Marten populations in uncut and logged boreal forests in 

Ontario. Journal of Wildlife Management. 58: 272–280.

Thompson, I.D.; Davidson, I.J.; O’Donnell, S.; Brazeau, F. 1989. Use of track 

transects to measure the relative occurrence of some boreal mammals in uncut 

forest and regeneration stands. Canadian Journal of Zoology. 67: 1816–1823.

Tibbels, A.E.; Kurta, A. 2003. Bat activity is low in thinned and unthinned stands 

of red pine. Canadian Journal of Forest Research. 33: 2436–2442.

Timmermans, S.T.A.; Badzinski, S.S.; Ingram, J.W. 2008. Associations between 

breeding marsh bird abundances and great lakes hydrology. Journal of Great 

Lakes Research. 34: 351–364.

Titus, J.R.; Vandruff, L.W. 1981. Response of the common loon (Gavia immer) 

to recreational pressure in the Boundary Waters Canoe Area northeastern 

Minnesota. Wildlife Monograph No. 79.

Tobalske, B.W. 1997. Lewis woodpecker (Melanerpes lewis). No. 284. In: Poole, 

A.; Gill, F., eds. The birds of North America. Philadelphia, PA: The Birds of 

North America, Inc.

Toland, B.R. 1985. Nest site selection, productivity, and food habits of northern 

harriers in southwest Missouri. Natural Areas Journal. 5: 22–27

Touchan, R.; Allen, C.D.; Swetnam, T.W. 1996. Fire history and climatic 

patterns in ponderosa pine and mixed-conifer forests of the Jemez Mountains, 

northwestern New Mexico. In: Allen, C.D., tech. ed. Fire effects in Southwestern 

forests: proceedings of the second La Mesa fire symposium. Fort Collins, CO: 

U.S. Department of Agriculture, Forest Service, Rocky Mountain Forest and 

Range Experiment Station: 33–46.
307

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Townsley, J.; Gaines, B.; Hadfield, J.; Harrod, R.; Mehmel, C.; Leyda, E. 

2004. Forest health assessment: Okanogan and Wenatchee National Forests. 

Wenatchee, WA: U.S. Department of Agriculture, Forest Service, Okanogan and 

Wenatchee National Forests. 105 p.

Tozer, D.C. 2002. Point count efficiency and nesting success in marsh-nesting 

birds. Peterborough, ON: Trent University. 162 p. M.S. thesis. 

Tremblay, J.A.; Ibarzabal, J.; Dussault, C.; Savard, J.-P.L. 2009. Habitat 

requirements of breeding black-backed woodpeckers (Picoides arcticus) in 

managed, unburned boreal forest. Avian Conservation and Ecology. 4(1): 2. 

URL: http://www.ace-eco.org/vol4/iss1/art2/.

Trombulak, S.C.; Frissell, C.A. 2000. Review of ecological effects of roads on 

terrestrial and aquatic communities. Conservation Biology. 14: 18–30.

Tuck, L.M. 1972. The snipes: a study of the genus Capella. Canadian Wildlife 

Service Monograph 5.

Turner, F.B. 1960. Population structure and dynamics of the western spotted frog, 

Rana pretiosa Baird and Girard, in Yellowstone Park, Wyoming. Ecological 

Monographs. 30: 251–278.

U.S. Department of Agriculture, Forest Service [USDA FS]. 2000. Land type 

associations of north central Washington. Wenatchee, WA: Okanogan and 

Wenatchee National Forests. 98 p.

U.S. Department of Agriculture, Forest Service [USDA FS]. 2006. Conducting 

species viability assessments for forest plan revision in Region 6. Portland, OR: 

U.S. Department of Agriculture, Forest Service, Pacific Northwest Region. 

U.S. Department of Agriculture, Natural Resources Conservation Service 

[USDA NRCS]. 2004. The PLANTS database, Version 3.5. Baton Rouge, LA: 

National Resources Conservation Service. http://plants.usda.gov. (June 15, 2010).

U.S. Department of the Interior, Bureau of Land Management [USDI BLM]. 

1979. Snake River birds of prey special research report to the Secretary of the 

Interior. Boise, ID. 

U.S. Department of the Interior, Fish and Wildlife Service [USDI FWS]. 2002.

Birds of conservation concern. Arlington, VI: Division of Migratory Bird 

Management. 99 p. http://migratorybirds.fws.gov/reports/bcc2002.pdf. 

(June 15, 2010). 
308

GENERAL TECHNICAL REPORT PNW-GTR-907

U.S. Department of the Interior, Fish and Wildlife Service [USDI FWS]. 2005.

Recovery outline for the Canada lynx. Missoula, MO.

U.S. Department of the Interior, Fish and Wildlife Service [USDI FWS]. 2011.

Final recovery plan for the northern spotted owl. Pacific Northwest Region, 

Portland, OR.

U.S. Department of the Interior, Geological Services [USGS]. 2004. Wood 

duck (Aix sponsa): requirements and limiting factors. www.npwrc.usgs.gov/

resource/1999/woodduck/wdreqlim. (June 15, 2010).

Vander Haegen, W.M. 2007. Fragmentation by agriculture influences reproductive 

success of birds in a shrubsteppe landscape. Ecological Applications. 17: 

934–947.

Vander Haegen, W.M.; Dobler, F.C.; Pierce, D.J. 2000. Shrubsteppe bird 

response to habitat and landscape variables in eastern Washington, U.S.A. 

Conservation Biology. 14: 1145–1160.

Vander Haegen, W.M.; Schroeder, M.A.; DeGraaf, R.M. 2002. Predation on real 

and artificial nests in shrubsteppe landscapes fragmented by agriculture. Condor. 

101: 496–506.

Verner, J.; Engelsen, G.H. 1970. Territories, multiple nest building, and polygyny 

in the long-billed marsh wren. Auk. 87: 557–567.

Vesely, D.G.; McComb, W.C. 2002. Salamander abundance and amphibian species 

richness in riparian buffer strips in the Oregon Coast Range. Forest Science. 

48(2): 291–297.

Villard, P.; Benniger, C.W. 1993. Foraging behavior of male black-backed and 

hairy woodpeckers in a forest burn. Journal of Field Ornithology. 64(1): 71–76.

Von Kienast, J.A. 2003. Winter habitat selection and food habits of lynx on the 

Okanogan Plateau, Washington. Seattle, WA: University of Washington. 64 p. 

M.S. thesis. 

Vos, C.C.; Chardon, J.P. 1998. Effects of habitat fragmentation and road density 

on the distribution pattern of the moor frog Rana arvalis. Journal of Applied 

Ecology. 35: 44–56.

Wackenhut, M.C. 1990. Bat species over-wintering in lava-tube caves in Lincoln, 

Gooding, Blaine, Bingham, and Butte Counties, Idaho. Pocatello, ID: Idaho State 

University. M.S. thesis.
309

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Wade, P.R. 2002. Bayesian population viability analysis. In: Beissinger, S.R.; 

McCullough, D.R., eds. Population viability analysis. Chicago, Il: University 

of Chicago Press: 213–238.

Walcheck, K.C. 1970. Nesting bird ecology of four plant communities in the 

Missouri River Breaks, Montana. Wilson Bulletin. 82: 370–382.

Waldien, D.L.; Hayes, J.P. 2001. Activity areas of female long-eared myotis in 

coniferous forests in western Oregon. Northwest Science. 75: 307–314.

Wales, B.C. 2001. The management of insects, disease, fire, and grazing and 

implications for terrestrial vertebrates using riparian habitats in eastern Oregon 

and Washington. Northwest Science. 75(Special Issue): 119–127.

Wallen, R.L.; Groves, C.R. 1989. Distribution, breeding biology, and nesting 

habitat of harlequin ducks in northern Idaho. Boise ID: Idaho Department of 

Fish and Game. 39 p.

Walston, L.J.; Mullin, S.J. 2007. Responses of a pond-breeding amphibian 

community to the experimental removal of predatory fish. American Midland 

Naturalist. 157: 63–73.

Washington Department of Fish and Wildlife [WDFW]. 1993. Status of the 

western gray squirrel (Sciurus griseus) in Washington. Olympia, WA. 33 p. 

Washington Department of Fish and Wildlife [WDFW]. 2006. Fish and wildlife 

geographic information system digital data documentation. Olympia, WA. 

Washington Department of Fish and Wildlife [WDFW]. 2005. Warmwater fish 

of Washington. Report FM93-9. Olympia, WA.

Washington, Department of Fish and Wildlife [WDFW]. 2008. Bighorn sheep 

Management Plan. Olympia, WA. 

Washington Wildlife Habitat Connectivity Working Group [WWHCWG]. 

2010. Washington Connected Landscape Project: statewide analysis. Washington 

Departments of Fish and Wildlife, and Transportation, Olympia, WA. http://

www.waconnected.org. (January 15, 2011).

Waters, T.F. 1995. Sediment in streams: sources, biological effects and control. 

American Fisheries Society Monograph 7. 

Watson, D. 1977. The hen harrier. Hertfordshire, England: T.E.A.D. Poyser, 

Limited, Berkhamsted. 307 p.
310

GENERAL TECHNICAL REPORT PNW-GTR-907

Watson, J. 1997. The golden eagle. First ed. London, United Kingdom: T. and A. 

D. Poyser. 

Watson, J.; Freidenberger, D.; Paull, D. 2001. An assessment of the focal species 

approach for conserving birds in variegated landscapes in southeastern Australia. 

Conservation Biology. 15(5): 1364–1373.

Watson, J.W. 1993. Responses of nesting bald eagles to helicopter surveys. 

Wildlife Society Bulletin. 21: 171–178.

Watson, J.W.; Pierce, D.J. 1998. Ecology of bald eagles in western Washington 

with an emphasis on the effects of human activity. Final report, Washington 

Department of Fish and Wildlife, Olympia, WA.

Watson, J.W.; Rodrick, E.A. 2000. Bald eagle. In: Management recommendations 

for Washington’s priority habitats and species. Olympia, WA: Washington 

Department of Fish and Wildlife: 9–1 to 9–15.

Webb, S.M.; Boyce, M.S. 2009. Marten fur harvests and landscape change in 

west-central Alberta. Journal of Wildlife Management. 73: 894–903.

Weber, W.C. 1980. A proposed list of rare and endangered bird species for 

British Columbia. In: Stace-Smith, R.; Johns, L.; Joslin, P., eds. Threatened and 

endangered species and habitats in British Columbia and the Yukon. Victoria, 

BC: British Columbia Ministry of the Environment Fish and Wildlife Branch: 

160–182.

Webster, J.D. 1975. The fox sparrow in southwestern Yukon and adjacent areas. 

Condor. 77: 215–216.

Weckstein, J.D.; Kroodsma, D.E.; Faucett, R.C. 2002. Fox sparrow (Passerella 

iliaca) In: Poole, A.; Gill, F. eds. The Birds of North America, No. 715. The Birds 

of North America, Inc., Philadelphia, Pennsylvania, U.S.A.

Wegner, S.J. 2008. Use of surrogates to predict the stressor response of imperiled 

species. Conservation Biology. 22(6): 1564–1571.

Welch, B.L. 2002. Bird counts of burned versus unburned big sagebrush sites. Res. 

Note. RMRS-RN-16. Fort Collins, CO: U.S. Department of Agriculture, Forest 

Service, Rocky Mountain Research Station.

Welch, N.E.; MacMahon, J.A. 2005. Identifying habitat variables important to the 

rare Columbia spotted frog in Utah (U.S.A.): an information-theoretic approach. 

Conservation Biology. 19: 473–481.
311

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Weller, T.J.; Zabel, C.J. 2001. Characteristics of fringed myotis day roosts in 

northern California. Journal of Wildlife Management. 65: 489–497.

Welsh, H.H.; Ollivier, L.M. 1998. Stream amphibians as indicators of ecosystem 

stress: a case study from California’s redwoods. Ecological Applications. 8(4): 

1118–1132.

Westerling, A.L.; Hidalgo, H.G.; Cayan, D.R.; Swetnam, T.W. 2006. Warming 

and earlier spring increase Western U.S. forest wildfire activity. Science. 313: 

940–943.

Wethington T.A.; Leslie, D.M., Jr.; Gregory, M.S.; Wethington, M.K. 1997.

Vegetative structure and land use relative to cave selection by endangered Ozark 

big-eared bats (Corynorhinus townsendii ingens). Southwestern Naturalist. 42: 

177–181.

Whitaker J.O., Jr.; Cross, S.P.; Skovlin, J.M.; Maser, C. 1983. Food habits of 

the spotted frog (Rana pretiosa) from managed sites in Grant County, Oregon. 

Northwest Science. 57: 147–154.

Whitaker, J.O., Jr.; Maser, C.; Keller, L.E. 1977. Food habits of bats of western 

Oregon. Northwest Science. 51: 46–55.

Whitfield, D.P.; Fielding, A.H.; McLeod, A.; Haworth, P.F. 2004. The effects 

of persecution on age of breeding and territory occupation in golden eagles in 

Scotland. Biological Conservation. 118: 249–259.

Whitt, M.B.; Prince, H.H.; Cox, R.R., Jr. 1999. Avian use of purple loosestrife 

dominated habitat relative to other vegetation types in a Lake Huron wetland 

complex. Wilson Bulletin. 111: 105–114.

Wiens, J.A.; Hayward, G.D.; Holthausen, R.S.; Wisdom, M.J. 2008. Using focal 

species and groups for conservation planning and management. BioScience. 

58(3): 241–252.

Wiens, J.A.; Hayward, G.D.; Safford, H.D.; Giffen, C.M. 2012. Historical 

environmental variation in conservation and natural resource management. 

Hoboken, NJ: Wiley-Blackwell.

Wiens, J.A.; Rotenberry, J.T. 1981. Habitat associations and community structure 

of birds in shrubsteppe environments. Ecological Monographs. 5: 21–41.

Wilbert, C.J.; Buskirk, S.W.; Gerow, K.G. 2000. Effects of weather and snow 

on habitat selection by American martens. Canadian Journal of Zoology. 78: 

1691–1696.
312

GENERAL TECHNICAL REPORT PNW-GTR-907

Wimberly, M.C.; Spies, T.A.; Long, C.J.; Whitlock, C. 2000. Simulating 

historical variability in the amount of old forests in the Oregon Coast Range. 

Conservation Biology. 14: 167–180.

Windsor, J. 1975. The response of peregrine falcons to aircraft and human 

disturbance. Canadian Wildlife Service Note 87.

Winter, M.; Johnson, D.H.; Faaborg, J. 2000. Evidence for edge effects on 

multiple levels in tallgrass prairie. Condor. 102: 256–266.

Wisdom, M.J.; Bate, L.J. 2008. Snag density varies with intensity of timber 

harvest and human access. Forest Ecology and Management. 255: 2085–2093.

Wisdom, M.J.; Holthausen, R.S.; Wales, B.C.; Hargis, C.D.; Saab, V.A.; Lee, 

D.C.; Hann, W.J.; Rich, T.D.; Rowland, M.M.; Murphy, W.J.; Eames, M.R. 

2000. Source habitats for terrestrial vertebrates of focus in the interior Columbia 

Basin: broad-scale trends and management implications. Gen. Tech. Rep. PNWGTR-485. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific 

Northwest Research Station. 3 vol.

Wisdom, M.J.; Wales, B.C.; Holthausen, R.S.; Hann, W.J.; Hemstrom, M.A.; 

Rowland, M.M. 2002. A habitat network for terrestrial wildlife in the interior 

Columbia Basin. Northwest Science. 76(1): 1–14.

Woodbridge, B.; Hargis, C.D. 2006. Northern goshawk inventory and monitoring 

technical guide. Gen. Tech. Rep. GTR-WO-71. Washington, DC: U.S. 

Department of Agriculture, Forest Service. 80 p. 

Woodruff, K.; Ferguson, H. 2005. Townsend’s big-eared bat (Corynorhinus 

townsendii). In: Management recommendations for Washington’s priority 

species. Volume V: Mammals. Olympia, WA: Washington Department of Fish 

and Wildlife: 1–13.

Worthing, P. 1993. Endangered and threatened wildlife and plants: finding on 

petition to list the spotted frog. Federal Register. 58: 38553.

Wright, C.S.; Agee, J.K. 2004. Fire and vegetation history in the eastern Cascade 

Mountains, Washington. Ecological Applications. 14(2): 443–459.

Wrightman, C.S.; Germaine, S.S. 2006. Forest stand characteristics altered by 

restoration affect western bluebird habitat quality. Restoration Ecology. 14 (4): 

653–661.
313

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Yanes, M.; Velasco, J.M.; Suarez, F. 1995. Permeability of roads and railways to 

vertebrates: the importance of culverts. Biological Conservation. 71: 217–222.

Yokom, C.F.; Harris, S.W.; Hansen, H.A. 1958. Status of grebes in eastern 

Washington. Auk. 75: 36–47

Young, J.S.; Hutto, R.L. 1999. Habitat and landscape factors affecting cowbird 

distribution in the Northern Rockies. Studies in Avian Biology. 18: 41–51.

Zeigenfuss, L.C.; Singer, F.J.; Gudorf, M.A. 2000. Test of a modified habitat 

suitability model for bighorn sheep. Restoration Ecology. 8(4S): 38–46.

Zielinski, W.J.; Slauson, K.M.; Carroll, C.; Kent, C.; Kudrna, D. 2001.

Status of American martens in coastal forests of the Pacific states. Journal

of Mammalogy. 82: 478–490.

Zuckerberg, B.; Porte, W.F. 2010. Thresholds in the long-term responses of 

breeding birds to forest cover and fragmentation. Biological Conservation. 143: 

952–962.

Zwartjes, P.W.; Cartron, J.-L. E.; Stoleson, P.L.L.; Haussamen, W.C.; Crane, 

T.E. 2005. Assessment of native species and ungulate grazing in the Southwest: 

terrestrial wildlife. Gen. Tech. Rep. RMRS-GTR-142. Fort Collins, CO: U.S. 

Department of Agriculture, Forest Service, Rocky Mountain Research Station. 

73 p.
314

GENERAL TECHNICAL REPORT PNW-GTR-907
315

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Appendix 1: Common and Scientific Names

Common name Scientific name

American marten Martes americana

Bald eagle Haliaeetus leucocephalus

Bighorn sheep Ovis canadensis

Black-backed woodpecker Picoides arcticus

Canada lynx Lynx canadensis

Cassin’s finch Carpodacus cassini

Columbia spotted frog Rana luteiventrus

Eared grebe Podiceps nigricollis

Fox sparrow Passerella lliaca

Golden eagle Aquila chrysaetos

Harlequin duck Histrionicus histrionicus

Larch mountain salamander Plethodon larselli

Lark sparrow Chondestes grammacus

Lewis’s woodpecker Melanerpes lewis

MacGillivray’s warbler Oporornis tolmiei

Marsh wren Cistothorus palustris

Northern bog lemming Synaptomys borealis

Northern goshawk Accipiter gentilis

Northern harrier Circus cyanus

Peregrine falcon Falco peregrinus

Pileated woodpecker Dyrocopus pileatus

Sage thrasher Oreoscoptes montanus

Tailed frog Ascaphus truei

Tiger salamander Abystoma tigrinum

Townsend’s big-eared bat Corynorhinus townsendii

Western bluebird Sialia mexicana

Western gray squirrel Sciurus griseus

White-headed woodpecker Picoides albolarvatus

Wilson’s snipe Gallinago delicata

Wolverine Gulo gulo

Wood duck Aix sponsa
316

GENERAL TECHNICAL REPORT PNW-GTR-907

Appendix 2: Species of Conservation Concern

Family Group Common name Surrogate

Alpine/boreal Alpine Gray-crowned rosy-finch F

Alpine/boreal Boreal forest Spruce grouse F*

Alpine/boreal Boreal forest Boreal owl F*

Alpine/boreal Boreal forest Boreal chickadee

Alpine/boreal Boreal forest Pine grosbeak

Alpine/boreal Boreal forest Pygmy shrew

Alpine/boreal Boreal forest Water vole F

Alpine/boreal Boreal forest Northern bog lemming F

Alpine/boreal Boreal forest Canada lynx F*

Alpine/boreal Boreal forest Moose

Forest mosaic All forest communities Northern goshawk F

Forest mosaic All forest communities Blue grouse

Forest mosaic All forest communities Band-tailed pigeon

Forest mosaic All forest communities Great gray owl

Forest mosaic All forest communities Long-eared owl

Medium/large trees All forest communities Sharp-shinned hawk

Medium/large trees All forest communities Rufous hummingbird

Medium/large trees All forest communities Williamson’s sapsucker

Medium/large trees All forest communities Hammond’s flycatcher

Medium/large trees All forest communities Cordilleran flycatcher

Medium/large trees All forest communities Mountain chickadee

Medium/large trees All forest communities Cassin’s finch F

Medium/large trees All forest communities Long-legged myotis

Medium/large trees All forest communities Silver-haired bat

Medium/large trees All forest communities Hoary bat

Medium/large trees All forest communities Red-tailed chipmunk

Medium/large trees All forest communities Northern flying squirrel

Medium/large trees Cool/moist forest Larch Mountain salamander F

Medium/large trees Cool/moist forest Spotted owl

Medium/large trees Cool/moist forest Vaux’s swift

Medium/large trees Cool/moist forest Pileated woodpecker F
317

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Family Group Common name Surrogate

Medium/large trees Cool/moist forest Chestnut-backed chickadee

Medium/large trees Cool/moist forest Brown creeper

Medium/large trees Cool/moist forest Winter wren

Medium/large trees Cool/moist forest Golden-crowned kinglet

Medium/large trees Cool/moist forest Ruby-crowned kinglet

Medium/large trees Cool/moist forest Varied thrush

Medium/large trees Cool/moist forest Hermit warbler

Medium/large trees Cool/moist forest American marten F

Medium/large trees Cool/moist forest Fisher

Medium/large trees Cool/moist forest Caribou

Medium/large trees Dry forest Flammulated owl

Medium/large trees Dry forest White-headed woodpecker F

Medium/large trees Dry forest Purple martin

Medium/large trees Dry forest White-breasted nuthatch

Medium/large trees Dry forest Pygmy nuthatch

Medium/large trees Dry forest Ringtail

Open forest All forest communities Rubber boa

Open forest All forest communities Sharptail snake

Open forest All forest communities Cassin’s vireo

Open forest All forest communities Western bluebird F

Open forest All forest communities Nashville warbler

Open forest All forest communities Purple finch

Open forest All forest communities Pine siskin

Open forest All forest communities Evening grosbeak

Open forest All forest communities California myotis

Open forest All forest communities Fringed myotis F

Open forest All forest communities Long-eared myotis

Open forest Early successional Townsend’s solitaire F

Open forest Early successional Fox sparrow F

Open forest Early successional Lazuli bunting

Open forest Pine/oak - (medium to large tree) California mountain kingsnake F

Open forest Pine/oak - (medium to large tree) Acorn woodpecker F
318

GENERAL TECHNICAL REPORT PNW-GTR-907

Family Group Common name Surrogate

Open forest Pine/oak - (medium to large tree) Western gray squirrel F

Open forest Postfire habitat American kestrel

Open forest Postfire habitat Lewis’s woodpecker F

Open forest Postfire habitat Three-toed woodpecker

Open forest Postfire habitat Black-backed woodpecker F

Open forest Postfire habitat Olive-sided flycatcher

Open forest Postfire habitat Western wood-pewee

Upland grassland Upland grassland Upland sandpiper F

Human disturbance Habitat generalist Peregrine falcon F

Human disturbance Habitat generalist Gray wolf

Human disturbance Habitat generalist Grizzly bear

Human disturbance Habitat generalist Wolverine F

Woodland/grass/shrub Woodland/grass/shrub Pygmy horned lizard

Woodland/grass/shrub Woodland/grass/shrub Side-blotched lizard

Woodland/grass/shrub Woodland/grass/shrub Ringneck snake

Woodland/grass/shrub Woodland/grass/shrub Striped whipsnake

Woodland/gass/shrub Woodland/grass/shrub Ferruginous hawk

Woodland/grass/shrub Woodland/grass/shrub Golden eagle F

Woodland/grass/shrub Woodland/grass/shrub Prairie falcon

Woodland/grass/shrub Woodland/grass/shrub Common poorwill

Woodland/grass/shrub Woodland/grass/shrub White-throated swift

Woodland/grass/shrub Woodland/grass/shrub Black-billed magpie

Woodland/gass/shrub Woodland/grass/shrub Canyon wren

Woodland/grass/shrub Woodland/grass/shrub Lark sparrow F

Woodland/grass/shrub Woodland/grass/shrub Brewer’s blackbird

Woodland/grass/shrub Woodland/grass/shrub Western small-footed myotis

Woodland/grass/shrub Woodland/grass/shrub Yuma myotis

Woodland/grass/shrub Woodland/grass/shrub Spotted bat

Woodland/grass/shrub Woodland/grass/shrub Pallid bat F

Woodland/grass/shrub Juniper woodland Ash-throated flycatcher F

Woodland/grass/shrub Juniper woodland Pinyon jay

Woodland/grass/shrub Juniper woodland Lesser goldfinch
319

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Family Group Common name Surrogate

Woodland/grass/shrub Woodland/shrub Sagebrush lizard

Woodland/grass/shrub Woodland/shrub Night snake

Woodland/grass/shrub Woodland/shrub Gray flycatcher

Woodland/grass/shrub Woodland/shrub Loggerhead shrike F

Woodland/grass/shrub Woodland/shrub Green-tailed towhee

Woodland/grass/shrub Woodland/shrub Merriam’s shrew

Woodland/grass/shrub Shrub Desert horned lizard

Woodland/grass/shrub Shrub Greater sage grouse F*

Woodland/grass/shrub Shrub Sage thrasher F*

Woodland/grass/shrub Shrub Brewer’s sparrow

Woodland/grass/shrub Shrub Black-throated sparrow

Woodland/grass/shrub Shrub Sage sparrow

Woodland/grass/shrub Shrub Pygmy rabbit

Woodland/grass/shrub Shrub Black-tailed jackrabbit

Woodland/grass/shrub Grass/shrub Tiger salamander F

Woodland/grass/shrub Grass/shrub Sharp-tailed grouse

Woodland/grass/shrub Grass/shrub Long-billed curlew

Woodland/grass/shrub Grass/shrub Burrowing owl

Woodland/grass/shrub Grass/shrub Horned lark

Woodland/grass/shrub Grass/shrub Oregon vesper sparrow

Woodland/grass/shrub Grass/shrub Western meadowlark

Woodland/grass/shrub Grass/shrub Preble’s shrew

Woodland/grass/shrub Grass/shrub White-tailed jackrabbit

Woodland/grass/shrub Grass/shrub Ord’s kangaroo rat

Woodland/grass/shrub Grass/shrub Sagebrush vole

Woodland/grass/shrub Grass/shrub American badger

Woodland/grass/shrub Grass/shrub Pronghorn

Woodland/grass/shrub Grass/shrub Mountain goat

Woodland/grass/shrub Grass/shrub Rocky mountain bighorn sheep f

Woodland/grass/shrub Grass/shrub California bighorn f

Woodland/grass/shrub Grassland Northern harrier F*

Woodland/grass/shrub Grassland Swainson’s hawk F*
320

GENERAL TECHNICAL REPORT PNW-GTR-907

Family Group Common name Surrogate

Woodland/grass/shrub Grassland Short-eared owl

Woodland/grass/shrub Grassland Grasshopper sparrow F*

Chambers/caves Chambers/caves Townsend’s big-eared bat F

Chambers/caves Chambers/caves Brazilian free-tailed bat

Riparian Conifer riparian Inland tailed frog F

Riparian Conifer riparian Black swift F

Riparian riparian/lg tree or snag/open water Wood duck F

Riparian riparian/lg tree or snag/open water Harlequin duck F

Riparian riparian/lg tree or snag/open water Bufflehead

Riparian riparian/lg tree or snag/open water Common goldeneye

Riparian riparian/lg tree or snag/open water Barrow’s goldeneye

Riparian riparian/lg tree or snag/open water Hooded merganser

Riparian riparian/lg tree or snag/open water Common merganser

Riparian riparian/lg tree or snag/open water Bald eagle F

Riparian Shrubby/deciduous riparian Mountain quail

Riparian Shrubby/deciduous riparian Yellow-billed cuckoo

Riparian Shrubby/deciduous riparian Western screech-owl

Riparian Shrubby/deciduous riparian Red-naped sapsucker F

Riparian Shrubby/deciduous riparian Willow flycatcher

Riparian Shrubby/deciduous riparian Red-eyed vireo

Riparian Shrubby/deciduous riparian Veery

Riparian Shrubby/deciduous riparian Yellow warbler

Riparian Shrubby/deciduous riparian American redstart

Riparian Shrubby/deciduous riparian Northern waterthrush

Riparian Shrubby/deciduous riparian MacGillivray’s warbler F

Riparian Shrubby/deciduous riparian Wilson’s warbler

Riparian Shrubby/deciduous riparian Yellow-breasted chat

Riparian Shrubby/deciduous riparian Water shrew

Riparian Marsh with adjacent large trees Great blue heron

Riparian Marsh with adjacent large trees Great egret

Riparian Marsh with adjacent large trees Green heron

Riparian Marsh with adjacent large trees Black-crowned night-heron F
321

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Family Group Common name Surrogate

Riparian Pond/small lake/backwater Painted turtle F

Riparian Pond/small lake/backwater Western pond turtle F

Riparian Pond/small lake/backwater Western toad

Riparian Pond/small lake/backwater Woodhouse’s toad F

Riparian Pond/small lake/backwater Cascades frog F

Riparian Pond/small lake/backwater Oregon spotted frog F*

Riparian Pond/small lake/backwater Columbia spotted frog F*

Riparian Pond/small lake/backwater Spotted sandpiper

Riparian Banks Northern rough-winged swallow F

Wetland Marsh American bittern

Wetland Marsh Least bittern

Wetland Marsh Snowy egret

Wetland Marsh Yellow rail

Wetland Marsh Virginia rail

Wetland Marsh Marsh wren F

Wetland Marsh Tricolored blackbird

Wetland Marsh Yellow-headed blackbird

Wetland Marsh/wet meadow White-faced ibis

Wetland Marsh/wet meadow Sandhill crane

Wetland Marsh/wet meadow Killdeer

Wetland Marsh/wet meadow Black-necked stilt

Wetland Marsh/wet meadow American avocet F

Wetland Marsh/wet meadow Greater yellowlegs

Wetland Marsh/wet meadow Willet

Wetland Marsh/wet meadow Wilson’s snipe F

Wetland Marsh/wet meadow Wilson’s phalarope

Wetland Marsh/wet meadow Franklin’s gull

Wetland Marsh/wet meadow Bobolink

Wetland Marsh/open water Common loon

Wetland Marsh/open water Pied-billed grebe

Wetland Marsh/open water Horned grebe

Wetland Marsh/open water Red-necked grebe
322

GENERAL TECHNICAL REPORT PNW-GTR-907

Family Group Common name Surrogate

Wetland Marsh/open water Eared grebe F

Wetland Marsh/open water Western grebe

Wetland Marsh/open water Clark’s grebe

Wetland Marsh/open water American white pelican

Wetland Marsh/open water Trumpeter swan

Wetland Marsh/open water Blue-winged teal

Wetland Marsh/open water Northern shoveler

Wetland Marsh/open water Northern pintail

Wetland Marsh/open water Green-winged teal

Wetland Marsh/open water Canvasback

Wetland Marsh/open water Redhead

Wetland Marsh/open water Ring-necked duck

Wetland Marsh/open water Greater scaup

Wetland Marsh/open water Lesser scaup

Wetland Marsh/open water Ruddy duck

Wetland Marsh/open water Caspian tern

Wetland Marsh/open water Forster’s tern

Wetland Marsh/open water Black tern

F-indicates a surrogate species for the group that could be addressed in the development of management actions.

F*-indicates a choice of which surrogate species to use. Managers from different areas may choose different species 

primarily based on the distribution of the species.

f-indicates a species that had localized populations that were confined to very specific habitats. Proposed management 

alternatives for these species would be applied only to local areas.
323

Terrestrial Species Viability Assessment for National Forests in Northeastern Washington

Appendix 3: Members of Working Groups

USFS Pacific Northwest Region Species Viability Assessment Workgroup

Shawne Mohoric–Team Co-Leader 

Planning biologist (retired) 

USDA Forest Service 

Pacific Northwest Regional Office

Kim Mellen-McLean–Team Co-Leader 

Regional wildlife ecologist 

USDA Forest Service 

Pacific Northwest Regional Office

Barbara Wales

Wildlife biologist 

USDA Forest Service 

Pacific Northwest Research Station

William Gaines

Forest wildlife ecologist (retired) 

USDA Forest Service 

Okanogan-Wenatchee National Forest

Lowell Suring 

Wildlife ecologist (retired) 

USDA Forest Service 

Washington Office

Pam Corey

Planning biologist 

USDA Forest Service 

Pacific Northwest Regional Office

Robert Mason

Planning biologist (retired) 

USDA Forest Service 

Blue Mountains Planning Unit

James Begley

Wildlife biologist/GIS specialist 

USDA Forest Service 

Okanogan-Wenatchee National Forest

USFS Pacific Northwest Region Species Viability Science Review Team

John Lehmkuhl

Research wildlife Biologist (retired) 

USDA Forest Service 

Pacific Northwest Research Station

Wenatchee Forestry Sciences Lab

Michael Wisdom

Research wildlife biologist 

USDA Forest Service 

Pacific Northwest Research Station

La Grande Forest and Rangeland

Sciences Laboratory

Martin Raphael

Research wildlife biologist 

USDA Forest Service 

Pacific Northwest Research Station

Olympia Lab

Bruce Marcot

Research ecologist 

USDA Forest Service 

Pacific Northwest Research Station

Portland Laboratory

Richard Holthausen

National wildlife ecologist (retired) 

USDA Forest Service 

Washington Office
324

GENERAL TECHNICAL REPORT PNW-GTR-907

Experts Consulted During Species Model Development

Name Affiliation Area of expertise

Robert Altman American Bird Conservancy Avian ecology

Peter Singleton USDA Pacific Northwest Research Station Carnivore ecology

Landscape permeability

Robert Naney USDA Forest Service, Pacific Northwest Region

Carnivore Species Leader

Carnivore ecology and management

Evelyn Bull USDA Pacific Northwest Research Station Woodpecker and amphibian ecology

Patricia Garvey-Darda USDA Forest Service, Wenatchee National Forest Amphibian ecology

Joseph Buchanan Washington Department of Fish and Wildlife Raptor ecologist

Victoria Saab USDA Forest Service, Rocky Mountain Research Station Avian ecology

Field Biologist Review Teams

Forest reviewed Name and position District/agency

Okanogan John Rohrer, district wildlife biologist Methow Ranger District

Okanogan Scott Fitkin, district biologist Washington Department of Fish and Wildlife

Okanogan Jeremy Anderson, district wildlife biologist Tonasket Ranger District

Okanogan Robert Naney, forest wildlife biologist Okanogan National Forest

Colville Chris Loggers, district wildlife biologist Colville National Forest

Colville James McGowan, forest wildlife biologist Colville National Forest

Wenatchee Mallory Lenz, district wildlife biologist Chelan Ranger District

Wenatchee Ann Sprague, district wildlife biologist Entiat Ranger District

Wenatchee Don Youkey, district wildlife biologist Wenatchee River Ranger District

Wenatchee JoEllen Richards, district wildlife biologist Cle Elum Ranger District 

Wenatchee Peter Forbes, district wildlife biologist Naches Ranger District

Wenatchee Beau Patterson, district biologist Washington Department of Fish and Wildlife
Pacific Northwest Research Station

Website http://www.fs.fed.us/pnw

Telephone (503) 808-2592

Publication requests (503) 808-2138

FAX (503) 808-2130

E-mail pnw_pnwpubs@fs.fed.us

Mailing address Publications Distribution 

Pacific Northwest Research Station

P.O. Box 3890 

	 	 Portland, OR 97208-3890
U.S. Department of Agriculture 

Pacific Northwest Research Station

1220 SW 3rd Ave., Suite 1400 

P.O. Box 3890 

Portland, OR 97208-3890

Official Business

Penalty for Private Use, $300