Assessing the Cumulative Effects of 

Linear Recreation Routes on Wildlife 

Habitats on the Okanogan and 

Wenatchee National Forests

William L. Gaines, Peter H. Singleton, and Roger C. Ross

United States

Department of

Agriculture

Forest Service

Pacific Northwest

Research Station

General Technical 

Report

PNW-GTR-586

November 2003
Authors William L. Gaines is a forest wildlife ecologist, Okanogan and Wenatchee 

National Forests, 215 Melody Lane, Wenatchee, WA 98801; Peter H. Singleton

is an ecologist, Pacific Northwest Research Station, Wenatchee Forestry 

Sciences Laboratory, 1133 N Western Ave., Wenatchee, WA 98801; and 

Roger C. Ross is a recreation planner, Okanogan and Wenatchee National 

Forests, Lake Wenatchee and Leavenworth Ranger Districts, 600 Sherbourne, 

Leavenworth, WA 98826.
Abstract Gaines, William L.; Singleton, Peter H.; Ross, Roger 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.

We conducted a literature review to document the effects of linear recreation routes on 

focal wildlife species. We identified a variety of interactions between focal species and 

roads, motorized trails, and nonmotorized trails. We used the available science to develop simple geographic information system-based models to evaluate the cumulative 

effects of recreational routes on habitats for focal wildlife species for a portion of the 

Okanogan and Wenatchee National Forests in the state of Washington. This process 

yielded a basis for the consistent evaluation of the cumulative effects of roads and 

recreation trails on wildlife habitats, and identified information gaps for future research 

and monitoring. We suggest that managers use an adaptive management approach to 

address wildlife and recreation interactions because of the complexity and uncertainty 

of these issues.

Keywords: Okanogan and Wenatchee National Forests, linear recreation routes, focal 

wildlife species, cumulative effects.
Summary We conducted a literature review to document the effects of linear recreation routes 

(roads, motorized trails, nonmotorized trails, designated and groomed ski and snowmobile routes) on wildlife and to assess the current level of human influences on focal wildlife species habitats on a portion of the Okanogan and Wenatchee National 

Forests in the state of Washington. The assessment consisted of seven steps: (1) 

identification of wildlife species and groups, ( 2) identification of focal species within 

each wildlife group, (3) identification of the road- and trail-associated factors for each 

focal species, (4) development of assessment processes and geographic information 

system (GIS) models to evaluate the influence of road- and trail-associated factors on 

focal species habitats, (5) application of the models to assess the current conditions 

of focal species habitats, (6) identification of information gaps, and (7) monitoring and 

adaptive management. Completion of this process yields a basis for the consistent 

evaluation of the cumulative effects of roads and recreation trails on wildlife habitats 

relative to the existing baseline conditions.

We identified 238 articles on the effects of recreation trails, roads, and related subjects on wildlife. Of these, 183 articles were used to identify the interactions between 

roads and recreation trails and 29 focal wildlife species. These articles included 

technical publications, books, agency publications, theses, and dissertations.

There is more science available to describe the interactions between focal wildlife 

species and roads than between focal species and recreation trails. Much of the 

research has been focused on wide-ranging carnivores and ungulates. Other lesser 

known species could benefit from additional research on the effects of roads, especially for less mobile species where roads may inhibit movements or fragment habitats. 

The most common reported interactions included displacement and avoidance where 

animals were reported as altering their use of habitats in response to roads or road 

networks. Disturbance at a specific site was also commonly reported and included 

disruption of animal nesting, breeding, or wintering areas. Collisions between animals 

and vehicles were commonly reported and affected a diversity of wildlife species, from 

large mammals to amphibians. Finally, edge effects associated with roads or road 

networks constructed within habitats, especially late-successional forests, were commonly identified. 

Fewer wildlife species have been studied relative to their interactions with motorized 

trails. Ungulates and some wide-ranging carnivore species were the most studied, and 

many wildlife species could benefit from further research designed to identify these 

interactions. The most common interaction identified in the literature includes displacement and avoidance where animals altered their use of habitats in response to motorized trails or trail networks. Disturbance at a specific site also was identified and, as 

with roads, was usually associated with wildlife breeding or rearing young.

The most common interactions reported in the literature that we reviewed between 

nonmotorized trails and focal wildlife species were displacement and avoidance, which 

altered habitat use, and disturbance at a specific site during a critical period. The interactions of the focal species and motorized or nonmotorized trails were quite similar. 

Depending on the wildlife species, some were more sensitive to motorized trail use, 

whereas others were more sensitive to nonmotorized trail use. Based on our current 

understanding, both forms of recreation have effects on wildlife. Motorized trails had 

a somewhat greater magnitude of effects, such as longer distances in which wildlife 

were displaced, for a greater number of the focal species we reviewed. Additional research would be useful to further refine the interactions of specific species with motorized and nonmotorized trails.
The interactions between snowmobile routes and focal wildlife species are poorly 

documented for many species. These interactions need to be further refined with 

additional research and monitoring. The most common interactions that we documented from the literature included trapping as facilitated by winter human access, 

displacement and avoidance, and disturbance at a specific site, usually wintering 

areas. An additional interaction that occurred on winter recreation routes was the 

effect of snow compaction on the subnivean sites used by small mammals. Small 

mammals can either be suffocated as a result of the compaction, or their subnivean 

movements can be altered owing to impenetrable compact snow. Snow compaction 

associated with snowmobiling also was identified as altering the competitor/predator 

communities because the packed snow routes provide winter access to areas not 

normally available to some species.

We documented only a few interactions between ski trails and focal wildlife species 

because of the limited literature available on the subject. Ungulates were the most 

thoroughly studied group, and few others had been investigated. The most common 

interactions that we found in the literature included trapping facilitated by winter route 

access, displacement and avoidance, and disturbance at a specific site (wintering 

areas in this case). As with snowmobile routes, ski trails also included the interactions 

of snow compaction and competitor/predator community alterations.

We developed 18 simple GIS models to estimate the current level of influence of linear 

recreation routes on focal wildlife species habitats. Four of the models addressed 

winter recreation, 11 nonwinter, and 3 included winter and spring periods. Fifteen of 

these models were applied to a case study area on a portion of the Okanogan and 

Wenatchee National Forests to illustrate their use and interpretation. The application 

of the cumulative effects models showed that, in general, nonwinter activities had a 

higher level of cumulative effects than groomed and designated winter route activities. 

Habitats in which cumulative effects were ranked as having a high level of human 

influence in many analysis units included core areas for grizzly bears (Ursus arctos), 

late-successional habitats, riparian habitats, and lake and riverine habitats. The 

effectiveness of these habitats could be restored by using some of the approaches 

described in this document.

During this review, we noted information gaps that hindered our understanding of 

wildlife, road, and recreation trail interactions. More and better defined information of 

the following suggested areas of study could help fill these gaps: (1) the interactions 

between wildlife and nonmotorized trails, snowmobile routes, and ski trails for many 

wildlife species, especially those with small home ranges and limited mobility; (2) the 

interactions between wildlife and the intensity of human use on recreation trails (such 

as trail density or number of hikers per unit time); (3) the interactions between wildlife 

habitat use and the spatial extent (such as the proportion of a home range or watershed) of recreational activity; and (4) finally, the relation of recreation trail and wildlife 

interactions to the demography of a species of management interest. Adaptive management and monitoring designed to lead to greater understanding of any of these 

areas would greatly facilitate our management goals of conserving ecosystem processes and functions while providing recreation opportunities. These areas of study 

all could be accomplished through the use of an adaptive management approach and 

well-designed monitoring and research.
The information provided in this review, and subsequent development and application of cumulative effects models, improves the knowledge base that can be used to 

evaluate project proposals and make informed decisions. The findings of our review 

agree with the findings of other reviews. In addition, this information can be used to 

develop and apply mitigation tools to address the kinds of interactions that have been 

described for each focal wildlife species or group. Tools that have been used to mitigate recreational activities include (1) Spatial separation of humans and wildlife in key 

habitats. This could be used to address situations where displacement and avoidance interactions have been identified for a wildlife species of management interest. 

(2) Temporal separation of humans and wildlife at critical periods. This tool could be 

applied where the interaction of displacement at a specific site has been identified for 

a wildlife species of management interest. (3) Human behaviors that reduce the effects of recreation on wildlife. These can be taught through information and education 

programs. (4) Identification of wildlife habitat issues in the early stages of projects. The 

information provided in this assessment may help address habitat issues proactively 

through project design.

To proactively address wildlife conservation and recreation opportunities, we need to 

begin addressing these issues through our landscape-scale planning processes. In 

this manner, important habitats for wildlife and recreational opportunities for humans 

can be identified. This process could be accomplished by using the following approach: (1) assess the existing level of influence that recreational activities have on 

wildlife habitats, (2) set compatible wildlife habitat goals and recreation goals, (3) gain 

further knowledge about wildlife and recreation interactions through an adaptive management approach, and (4) adapt habitat and recreation goals based on new information. By using this approach, we can address the mutual goals of conserving wildlife 

species while providing recreation opportunities. These goals have many commonalities, not the least of which is the desire of people to experience wildlife during their 

recreational outings.
Contents 1 The Assessment Process

 1 Introduction

 2 Methods

 8 Document Organization

 8 Overview of Interactions Between Focal Wildlife Species and 

 Linear Recreation Routes

 8 Literature Review

 12 Information Gaps

 13 Wide-Ranging Carnivore Habitat Assessment

 13 Introduction and Focal Species Selection

 13 Summary of Recreation Route-Associated Factors for Focal Species

 15 Assessment Processes for Focal Species

 18 Information Gaps and Research Needs

 19 Monitoring and Adaptive Management

 19 Ungulate Winter and Summer Habitat Assessment

 19 Introduction and Focal Species Selection

 19 Summary of Recreation Route-Associated Factors for Focal Species

 22 Assessment Processes for Focal Species

 25 Information Gaps and Research Needs

 25 Monitoring and Adaptive Management

 25 Late-Successional Forest Habitat Assessment

 25 Introduction and Focal Species Selection

 25 Summary of Recreation Route-Associated Factors for Focal Species

 29 Assessment Processes for Focal Species

30 Information Gaps and Research

 30 Monitoring and Adaptive Management

 31 Riparian Habitat Assessment

 31 Introduction and Focal Species Selection

 31 Summary of Recreation Route-Associated Factors for Focal Species

 34 Assessment Processes for Focal Species

 35 Information Gaps and Research

 35 Monitoring and Adaptive Management

 36 Waterfowl and Colonial Nesting Bird Habitat Assessment

 36 Introduction and Focal Species Selection
 36 Summary of Recreation Route-Associated Factors for Focal Species

 37 Assessment Processes for Focal Species

 38 Information Gaps and Research Needs

 38 Monitoring and Adaptive Management

 38 Primary Cavity Excavator Habitat Assessment

 38 Introduction and Focal Species Selection

 38 Summary of Recreation Route-Associated Factors for Focal Species

 39 Assessment Processes for Focal Species

 39 Information Gaps and Research

 39 Monitoring and Adaptive Management

 40 Application of the Recreation Route Cumulative Effects Models: 

 A Case Study

 40 Assessment Area

 40 Assessment Models Applied

 40 Results and Discussion

 49 Management Implications

 51 Monitoring and Adaptive Management

 51 An Adaptive-Management and Monitoring Process

 52 A Hypothetical Adaptive-Management Plan

 54 Conclusion

54 Acknowledgments

55 English Equivalents

 55 Literature Cited

71 Appendix
1

The Assessment 

Process

Introduction

Increasing demand for recreational opportunities and facilities (Burchfield et al. 2000, 

USDA FS 2000b) has resulted in controversy over the potential effects of these activities on wildlife (Flather and Cordell 1995). On national forest lands, management is 

focused on providing recreational opportunities compatible with ecosystem processes 

and functions (USDA FS 2000b). Understanding how recreational activities influence 

ecosystem processes and functions is necessary to evaluate different management 

options and to make informed decisions. 

As demands for recreation increase, so do cumulative effects on wildlife species and 

their habitats over space and time. Cumulative effects can be defined as the combined 

effect on a species or its habitat caused by the activity or program at hand, as well 

as other reasonably foreseeable events that are likely to have similar effects on the 

species or habitat (Weaver et al. 1987). Cumulative effects analysis assesses the effects on a system of spatial and temporal perturbations resulting from human activities 

(Beanlands et al. 1986). Cumulative effects analysis explicitly deals with effects and 

whether those effects exceed or fall short of thresholds compatible with the population or habitat goals for a given species or group of species. Hence, cumulative effects 

analysis and its attendant models are tools to perform proactive conservation for wildlife species and habitats (Weaver et al. 1987). 

Although a considerable and growing body of research is available concerning recreation and wildlife interactions (Joslin and Youmans 1999, Knight and Gutzwiller 1995), 

significant gaps in our knowledge remain. Gathering reliable knowledge can be time 

consuming and costly because of the difficulty in controlling an array of variables that 

influence how wildlife reacts to human activities. Because of this, the investigation of 

wildlife and recreation interactions is well suited to an adaptive management approach 

(Gutzwiller 1993, Knight and Gutzwiller 1995). 

Recreation on national forest lands includes a wide variety of activities with a correspondingly wide range of effects on wildlife. Because of this, it was necessary to 

narrow the scope of recreational activities considered in this assessment. Therefore, 

this assessment is focused on linear recreational routes; including motorized and 

nonmotorized trails, winter ski trails, snowmobile routes, and forest roads. These activities account for most of the recreational activities and potential effects on wildlife 

habitats that occur on the Okanogan and Wenatchee National Forests. Future efforts 

should be focused on providing a summary of the available science about other types 

of recreational activities and wildlife interactions such as helicopter skiing, rock-climbing, snow-play areas, and several others, which were beyond the scope and funding 

of this effort. The processes and methods developed in this assessment would greatly 

facilitate the incorporation of these other recreational activities. 

This assessment has been designed with three primary objectives in mind: (1) develop a baseline of information about roads, recreation trails, and wildlife interactions 

through a review of relevant literature; (2) develop assessment processes and geographic information system (GIS) models for the consistent evaluation of the cumulative effects of these activities on wildlife habitats; and (3) use the processes and 

models to complete a case study assessment of the effects of existing roads and 

recreation trails on wildlife habitats for the Okanogan and Wenatchee National Forest 

lands located between Interstate 90 and Lake Chelan. 
2

The assessment process consists of seven steps: (1) identify wildlife species and 

groups; (2) identify focal species within each wildlife group; (3) identify the road- and 

trail-associated factors for each focal species; (4) develop assessment processes and 

GIS models to evaluate the influence of road- and trail-associated factors on focal 

species habitats, including the development of preliminary cumulative effects thresholds; (5) apply the models to assess the current conditions of focal species habitats; 

(6) identify information gaps; and (7) monitor and apply adaptive management approaches. This process yields a basis for the consistent evaluation of the cumulative 

effects of roads and recreation trails on wildlife habitats relative to the existing baseline 

conditions. In addition, this process can be used to address other types of recreational 

activities and assess their cumulative effects on wildlife habitats. 

Step 1. Identify wildlife species and groups—We used existing information about 

the distribution of wildlife species on the Okanogan and Wenatchee National Forests 

to develop a list of wildlife species and to develop groups of species based on their 

biology (e.g., wide-ranging carnivores, late-successional species, riparian-associated 

species, etc.) and interactions with road- and recreation trail-associated factors. These 

information sources included watershed assessments, late-successional reserve assessments (USDA FS 1997), and information from the Washington gap analysis program (GAP) (Dvornich et al. 1997, Johnson and Cassidy 1997, Smith et al. 1997). 

In all, 395 species are included in this assessment (see app.). These included 9 

amphibian species, 11 reptile species, 286 bird species, 84 mammal species, and 5 

mollusks. These species were placed into six groups (some species occurred in more 

than one group and habitat generalist species were not assigned to any group), which 

included: 

1. Wide-ranging carnivores (9 species) 

2. Ungulates (6 species)

3. Late-successional forest habitat-associated species (71 species)

4. Riparian-associated species (144 species)

5. Waterfowl and colonial nesting birds (97 species)

6. Primary cavity excavators (11 species) 

Step 2. Identify focal wildlife species—Many systems have been used by ecologists to evaluate or rank potential emphasis species (Kuhnke and Watkins 1999, 

Lambeck 1997, Lehmkuhl et al. 2001, Millsap et al. 1990, Noss et al. 1997). One approach that has been proposed is the “focal species” concept (Lambeck 1997, Noss 

et al. 1997) in which species that are most sensitive to a particular activity (habitat 

fragmentation, disturbance from a motorized trail, etc.) are used to define the acceptable levels of the activity for a group of species (such as wide-ranging carnivores). 

Lindenmayer et al. (2002) pointed out some of the limitations of the focal species concept, including a lack of testing to validate the approach. However, the focal species 

approach has recently been empirically tested for wide-ranging carnivores (Carroll 

et al. 2001) and birds (Watson et al. 2001) with favorable results. We, therefore, used 

this concept to select focal wildlife species that represented groups of wildlife species 

(table 1). 

Focal species, as described in the federal planning regulations (CFR Vol. 65 No. 218, 

November 2000), are species selected for use as surrogate measures in the assessment of ecological integrity. Their distribution and abundance over time provide 

Methods
3

Table 1—Focal wildlife species that were identified for each of the 6 wildlife 

groups used in this assessment

Wildlife group Focal species

Wide-ranging carnivores Grizzly bear, lynx, gray wolf, wolverine

Ungulates Mule deer, elk, bighorn sheep, mountain goats

Late-successional-forest- Northern spotted owl, northern goshawk, brown 

 associated species creeper, American marten, fisher, northern flying 

 squirrel, pygmy nuthatch, white-breasted nuthatch, 

 white-headed woodpecker

Riparian associated species Cascade frog, tailed frog, harlequin duck, bald 

 eagle, water shrew, black-capped chickadee

Waterfowl and colonial nesters Common loon, great blue heron, eared grebe, 

 wood duck

Primary cavity excavators White-headed woodpecker, three-toed woodpecker, 

 pileated woodpecker

insights into the integrity of the larger ecological system to which they belong. We 

selected species that represent the range of environments within the assessment 

area, and that serve an umbrella function, or play key roles in maintaining community 

structure or processes. Therefore, we selected focal species (1) whose habitat associations represented the range of habitats associated with the wildlife group, (2) whose 

road- and recreation trail-associated factors were representative of the range of the 

group, (3) whose populations or habitats could be monitored, (4) for which viability 

concerns were known such as federally listed or USDA Forest Service “sensitive” species, and (5) that were relatively well studied relative to the effects of road and trails on 

their habitat use. 

Step 3. Identify road- and trail-associated factors—Liddle (1997) provided a threetier disturbance classification scheme for the effects recreational activities have on 

wildlife. Disturbance type 1 occurs when an animal sees, hears, smells, or otherwise 

perceives the presence of a human but no contact is made and it may or may not alter 

its behavior. Disturbance type 2 is when habitat is changed in some way by pathway 

creation, camping, the presence of food, or clearing of vegetation. Disturbance type 3 

involves human actions in which there is a direct and damaging contact with the animal such as hunting, fishing, collisions with vehicles, and other accidental contact in 

which the results are similar to hunting. Alternatively, Knight and Cole (1995) provided 

a conceptual model of the responses of wildlife to recreational activities. They grouped 

the causes of recreation impacts to wildlife into harvest, habitat modification, pollution, 

and disturbance. 

For this assessment, these two broad classification schemes were refined to focus on 

road- and recreation trail-factors that affected wildlife, based on a review of relevant 

literature. The road- and recreation trail-associated factors were initially based on the 

factors developed by Wisdom et al. (1999) and a literature review by Singleton and 

Lehmkuhl (1998). These reviews were expanded to include additional factors associated with winter and nonwinter human use of recreation trails. The relationship between 

the general classification schemes proposed by Liddle (1997) and Knight and Cole 
4

(1995), and the road- and trail-associated factors used in this assessment are shown in 

table 2. Table 3 lists the road- and trail-associated factors along with their effects and 

groups of wildlife species that are affected by them. 

Based on a review of the scientific literature, road- and recreation trail-associated fac-

tors were identified for “focal” wildlife species for which information was available. The 

effects of road- and recreation trail-associated factors can be direct, such as habitat 

loss and fragmentation, or indirect, such as displacement or avoidance of areas near 

roads in relation to motorized traffic and associated human activities (Blakesley and 

Reese 1988, Miller et al. 1998, Reed et al. 1996, Wisdom et al. 2000). Recreation trailassociated factors were identified for nonmotorized trails, motorized trails, snowmobile 

routes, and ski trails. In addition, the road-associated factors developed by Wisdom et 

al. (1999) were summarized and expanded upon. 

Step 4. Processes and models—Assessment processes and models were devel

-

oped to provide a consistent approach to the evaluation of the cumulative effects of 

roads and recreation trails on wildlife habitats. These were based on the habitat re-

quirements of the focal species and the trail- and road-associated factors found to 

affect the focal species. The models and assessment processes were developed to 

use GIS and corresponding data layers that included roads, trails, wildlife habitats, 

watersheds, and subbasins. Ideally, these models would incorporate the following 

variables: (1) spatial extent of the immediate effect of the factor (such as distance a 

species was displaced from a road or trail), (2) the level of intensity of human use on a 

road or trail that resulted in a factor being identified as affecting the focal species (such 

as number of people per day or density of roads), and (3) the extent, or a threshold, of 

human influence (assessed by 1 and 2 above) on wildlife habitats within a given area, 

such as a watershed or subbasin (such as 50 percent of a watershed within a trail zone 

of influence with >10 people per day). 

Relatively reliable information was available for many focal species concerning the im-

mediate spatial effect, or the zone of influence, of a particular road- or trail-associated 

factor. Less information was available relating to the intensity of human use (number 

of vehicles per unit time or density of open roads) on the effect on wildlife and, conse-

quently, it was included in only a few of the models. There was even less information 

on the extent of human influence (such as the proportion of a home range within a 

zone of influence when use by a particular species significantly changes) on focal 

species habitat use; this area is ripe for research. 

The size of the analysis area used to evaluate cumulative effects was based on the 

mobility of focal species, and whether the focal species were habitat generalists or 

specialists. For example, wide-ranging carnivores typically have large home ranges, 

can travel large distances, and are habitat generalists. As a result, we chose large 

areas in which to address cumulative effects for these species. Conversely, several 

late-succession- and riparian-associated wildlife species have smaller home ranges, 

are less mobile, and are habitat specialists. Therefore, cumulative effects were as-

sessed by using specific habitats within 5th-field watersheds or habitat reserves. 

Because quantitative evaluation of cumulative recreation effects was not possible 

owing to data limitations for many species, we developed a qualitative ranking scheme. 

We assumed that the lower amount of roads and trails in an assessment area, the 

higher the probability of focal species persistence and the higher the probability that 

ecosystem processes and functions would be conserved (fig. 1). Consequently, we 

ranked cumulative linear recreation route effects to focal species as high, moderate, 
5

Table 2—Comparison of classification schemes used to describe the effects of recreation on wildlife and 

the road- and trail-associated factors used in this assessment

Road- and trail-associated Recreation

factorsa Disturbance typeb activityc Definition of associated factors

Hunting and trapping Disturbance type 3 Harvest Mortality from hunting or trapping as facilitated

 by road and trail access

Poaching Disturbance type 3 Harvest Increased illegal take of animals as facilitated by

 trails and roads

Collisions Disturbance type 3 Harvest Death or injury resulting from a motorized vehicle

 running over or hitting an animal

Negative human interactions Disturbance type 3 Harvest Increased mortality of animals (euthanasia or

 shooting) owing to increased contact with 

 humans, as facilitated by road and trail access

Movement barrier or filter Disturbance type 2 Habitat Interference with dispersal or other movements 

 modification as posed by a road or trail itself or by human 

 activities on or near roads, trails, or networks

Displacement or avoidance Disturbance type 1 Disturbance Spatial shifts in populations or individual animals 

 away from human activities on or near roads, 

 trails, or networks

Habitat loss and fragmentation Disturbance type 2 Habitat Loss and resulting fragmentation of habitat owing 

 modification to the establishment of roads, trails, or networks, 

 and associated human activities

Edge effects Disturbance type 2 Habitat Changes to habitat microclimates associated with 

 modification the edge induced by roads or trails

Snag or downed log reduction Disturbance type 2 Habitat Reduction in density of large snags and downed 

 modification logs owing to their removal near roads as 

 facilitated by road access

Collection Disturbance type 3 Harvest Collection of live animals for use as pets (such as 

 amphibians and reptiles) as facilitated by the 

 physical characteristics of roads or trails or by

 road or trail access

Route for competitors and Disturbance type 2 Habitat A physical human-induced change in the environ-

 predators modification ment that provides access for competitors or

 predators that would not have existed otherwise

Disturbance at a specific site Disturbance type 1 Disturbance Displacement of individual animals from a 

 specific location that is being used for 

 reproduction and rearing of young

Snow compaction Disturbance type 3 Habitat Direct mortality of animals crushed or suffocated 

 modification as a result of snow compaction from snowmobile

 routes or groomed ski trails

Physiological response Disturbance type 1 Disturbance Increase in heart rate or stress hormones when 

 near a road or trail or network of roads or trails

a Based in part on Wisdom et al. 1999.

b Disturbance type 1 occurs when an animal sees, hears, smells, or otherwise perceives the presence of a human but no contact is made and 

it may or may not alter its behavior. Disturbance type 2 is when habitat is changed in some way. Disturbance type 3 involves human actions in 

which there is direct and damaging contact with the animal. From Liddle 1997.

c From Knight and Cole 1995.
6

Table 3—Recreation trail- and road-associated factors with documented effects on habitat or populations of 

wildlife species, and the affected wildlife species groups

Road- and trailassociated factors Effects of the factors Wildlife group affected

Hunting and trapping Mortality from hunting or trapping as facilitated by road and trail access Wide-ranging carnivores

 Ungulates

Waterfowl

Poaching Increased illegal take of animals, as facilitated by trails and roads Wide-ranging carnivores

 Ungulates

Waterfowl

Collisions Death or injury resulting from a motorized vehicle running over or Wide-ranging carnivores

 hitting an animal Late successional

 Riparian associated

Ungulates

Negative human Increased mortality of animals (e.g., euthanasia or shooting) owing to Wide-ranging carnivores

 interactions increased contact with humans, as facilitated by road and trail access Ungulates

 Late successional

Movement barrier Alteration of dispersal or other movements as posed by a road or trail Wide-ranging carnivores

 or filter itself or by human activities on or near a road or trail or network Late successional

 Riparian associated

Ungulates

Displacement or Spatial shifts in populations or individual animals from a road or trail Wide-ranging carnivores

 avoidance or network in relation to human activities on or near a road or trail Late successional

 or network Riparian associated

 Ungulates

Habitat loss and Loss and resulting fragmentation of habitat owing to the establishment Wide-ranging carnivores

 fragmentation of roads and trails, road and trail networks, and associated human Late successional

 activities Riparian associated

 Ungulates

Primary cavity excavators

Edge effects Changes to habitat microclimates associated with the edge induced by Late successional

 roads or trails

Snag or downed log Reduction in density of large snags and downed logs owing to their Late successional

 reduction removal near roads or campsites, as facilitated by road access Riparian associated

 Primary cavity excavators

Collection Collection of live animals for use as pets (such as amphibians and Late successional

 reptiles), as facilitated by the physical characteristics of roads and Riparian associated

 trails or by road and trail access

Route for competitors A physical human-induced change in the environment that provides Wide-ranging carnivores

 or predators access for competitors or predators that would not have existed Late successional

 otherwise Riparian associated

Primary cavity excavators

Disturbance at a Displacement of individual animals from a specific location that is being Wide-ranging carnivores

 specific site used for reproduction and rearing young Late successional

Riparian associated

Ungulates

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

 compaction from snowmobile routes or groomed ski trails Riparian associated

Physiological response Changes in heart rate or level of stress hormones as a result Ungulates

 of proximity to a road or trail Late successional
7

or low depending largely on the extent of influence that these activities had on wildlife 

habitats within a given analysis area. Where possible, we linked these rankings to biological thresholds derived from our literature review. Where these data were lacking, 

we generally split the effects levels into quartiles to assign relative ranks. 

The assessment processes and models described in the document were designed 

to address broad-scale issues, such as cumulative effects, and to provide information that could be used to evaluate project-level effects. These models could best 

be viewed as working hypotheses about the interactions between roads, trails, and 

wildlife. As such, wildlife responses should be monitored and models adapted as new 

information becomes available. 

Step 5. Assess the current condition—We applied the assessment processes and 

models to evaluate the current condition of wildlife habitats for each of the effects 

of associated factors of the recreation activities (table 2) associated with roads and 

recreation trails. To complete this assessment, district recreation specialists updated 

GIS-based road and trail maps and attributed each trail or trail segment with information on trail use levels. This was completed for all the recreation trails that occurred in 

the assessment area. 

Step 6. Identify information gaps—The literature review, model-building exercises, 

and pilot study allowed for the identification of information gaps. These were summarized and prioritized, and potential research topics were identified for each group of 

wildlife species. 

Step 7. Monitor and apply adaptive management approaches—Because of our incomplete knowledge about many of the road, recreation trail, and wildlife interactions, 

assumptions were made to complete the assessment. Appropriate monitoring was 

identified to test the validity of our assumptions and to make management adjustments 

based on monitoring results. 

Figure 1—Hypothetical example showing the assumed relationship between increasing 

recreational use within wildlife habitats and the probability of focal species persistence and 

maintenance of ecosystem processes and functions.
8

The next section of this document focuses on different types of linear recreational 

routes and the documented effects they have on focal wildlife species. This overview 

is provided for different types of recreational routes, highlights the most common roadand trail-associated factors, and describes how pervasive these effects are across 

focal species. This section provides the reader with an idea of the range of road- and 

trail-associated factors and their likelihood of affecting focal species. 

The six sections (beginning on page 13) following the overview shifts the focus to wildlife species groups and focal wildlife species within each group. We describe documented specific effects of linear recreation routes on species groups and focal species 

to provide insights into how severe effects are likely to be when they occur. In these 

sections, we present assessment models and tools for specific focal species and species groups. 

Taken together, the overview and following sections for each species group provide 

information about the likelihood and magnitude of effects that is necessary to estimate 

cumulative effects. Examples of how these work together are presented for a case 

study area by using a portion of the Okanogan and Wenatchee National Forests, and 

includes interpretations of model outputs. The final section of this document discusses 

monitoring and adaptive management, and provides a hypothetical example of how 

these concepts can be applied to learn from recreation projects that could influence 

wildlife habitats. 

Here we provide an overview of the road- and trail-associated factors that were documented in the literature between the five types of linear recreation routes and 29 focal 

wildlife species (table 1). We provide this overview to illustrate the frequency with 

which various road- and trail-associated factors were documented in the literature and 

to summarize the relative status of our scientific understanding of how each of the five 

types of linear recreation routes affect focal wildlife species.

We reviewed 238 articles on the effects of recreation trails and roads on wildlife. Of 

these, 183 articles were used to identify the interactions between roads, recreation 

trails, and focal wildlife species. These articles included technical publications, books, 

agency publications, theses, and dissertations. Many of these references came from 

previous reviews (Boyle and Samson 1985, Joslin and Youmans 1999, Knight and 

Gutzwiller 1995, Liddle 1997). 

Road and focal wildlife species interactions—The science available to describe 

the interactions between focal wildlife species and roads is more developed than that 

available to describe the interactions between focal wildlife species and recreation 

trails. Much of the research has been focused on wide-ranging carnivores and ungulates. Other lesser known species could benefit from additional research on the effects 

of roads; this is especially true for less mobile species where roads may inhibit movements or fragment habitats. 

The most commonly reported interactions included displacement or avoidance where 

animals were reported as altering their use of habitats in response to roads or road 

networks (Cassier and Groves 1990, Hutto 1995, Johnson et al. 2000, Klein 1993, 

Mace et al. 1996, 1998) (fig. 2). Disturbance at a specific site was also commonly reported and included disruption of animal nesting, breeding, or wintering areas (Linnell 

et al. 2000, Papouchis et al. 2001, Skagen et al. 1991). Collisions between animals 

and vehicles were commonly reported and affected a diversity of wildlife species, from 

large mammals (Gibeau and Heuer 1996, Lehnert et al. 1996) to amphibians (Ashley 

Overview of 

Interactions Between 

Focal Wildlife 

Species and Linear 

Recreation Routes 

Document Organization

Literature Review
9

and Robinson 1996). Finally, edge effects associated with roads or road networks constructed within habitats, especially late-successional forests, were commonly identified 

(Hickman 1990, Miller et al. 1998). 

Motorized trails and focal wildlife interactions—Fewer wildlife species have been 

studied relative to the interactions with motorized trails compared to studies that have 

investigated wildlife and road interactions. Ungulates and some wide-ranging carnivore species were the best studied, and many wildlife species could benefit from 

further research designed to identify common factors involved in these interactions. 

One of the most common interactions identified in the literature includes displacement or avoidance where animals altered their use of habitats in response to motorized trails or trail networks (Kasworm and Manley 1990, Mace et al. 1996) (fig. 3). 

Disturbance at a specific site also was identified and, as with roads, was usually 

associated with breeding or rearing young (Foppen and Reijnen 1994, Phillips and 

Alldredge 2000). 

Nonmotorized trail and focal wildlife species interactions—The most common 

interactions reported in the literature that we reviewed between nonmotorized trails 

and focal wildlife species were displacement and avoidance, which altered habitat 

use (Kasworm and Manley 1990, Klein 1993, Miller et al. 1998, Swarthout and Steidl 

2001), and disturbance at a specific site during a critical period (Ashley 1994, Cassier 

and Groves 1989) (fig. 4). The interactions of focal species and motorized or nonmotorized trails were quite similar. Depending on the wildlife species, some were more 

sensitive to motorized trail use, whereas others were more sensitive to nonmotorized 

trail use. Based on our current level of understanding, both forms of recreation have 

effects on wildlife. Motorized trails had a somewhat greater magnitude of effects, such 

Figure 2—Interactions between the 29 focal wildlife species and roads documented from the literature 

review.
10

Figure 3—Interactions between the 29 focal wildlife species and motorized trails documented from the 

literature review.

Figure 4—Interactions between the 29 focal wildlife species and nonmotorized trails documented from the 

literature review.
11

Figure 5—Interactions between the 29 focal wildlife species and snowmobile routes documented from 

the literature review.

as longer distances in which wildlife were displaced, for a greater number of the focal 

species we reviewed. Additional research would be useful to further refine the interactions of specific species with motorized and nonmotorized trails. 

Snowmobile route and focal wildlife species interactions—The interactions between snowmobile routes and focal wildlife species are poorly documented for many 

species. These interactions need to be further refined with additional research and 

monitoring. The most common interactions that we documented from the literature 

included trapping and poaching facilitated by winter human access (Claar et al. 1999, 

Wisdom et al. 2000), displacement and avoidance (Cassier et al. 1992), and disturbance at a specific site (Copeland 1996, Hornocker and Hash 1981, Jonkel 1980, 

Linnell et al. 2000, Reynolds et al. 1986), usually wintering areas (fig. 5). An additional 

interaction that occurred for winter recreation routes was the effect that snow compaction has on the subnivean sites used by small mammals (Schmid 1972). Small 

mammals can either be suffocated as a result of the compaction, or their subnivean 

movements can be altered owing to impenetrable compact snow. Snow compaction 

associated with snowmobiling also was identified as altering the competitor/predator 

communities because the packed snow routes provide winter access to areas not normally available to some species (Buskirk 1999, Koehler and Aubry 1994, Ruediger et 

al. 2000). 

Ski trails and focal wildlife interactions—We documented only a few interactions 

between ski trails and focal wildlife species owing to the limited literature available 

on the subject. Ungulates were the most thoroughly studied group, and few others 

had been investigated. The most common interactions that we found in the literature 

included trapping facilitated by winter route access (Claar et al. 1999), displacement 

and avoidance (Ferguson and Keith 1982, Freddy et al. 1986), and disturbance at a 
12

Figure 6—Interactions between the 29 focal wildlife species and ski trails documented from 

the literature review.

Information Gaps

specific site, such as wintering areas (Canfield et al. 1999, Freddy et al. 1986) (fig. 6). 

As with snowmobile routes, ski trails also included the interactions of snow compaction and competitor/predator community alterations (Buskirk 1999, Koehler and Aubry 

1994, Ruediger et al. 2000). 

Over the course of this review, we kept track of information gaps that hindered our 

understanding of wildlife, road, and recreation trail interactions. Further research in the 

following suggested areas of study, which can be accomplished through the use of an 

adaptive management approach and well-designed monitoring and research (Gaines 

et al. 1999; Gutzwiller 1991, 1993), would help improve our understanding of wildlife, 

road, and recreation trail interactions. 

• The interactions between wildlife, nonmotorized trails, snowmobile routes, and 

ski trails for many wildlife species, especially those with small home ranges and 

limited mobility.

• The interactions between wildlife and the intensity of human use on recreation 

trails (such as trail density or number of hikers per unit time).

• The interactions between wildlife habitat use and the spatial extent (such as the 

proportion of a home range or watershed) of recreational activity.

• The relation of recreation trail and wildlife interactions to the demography of 

particular species of management interest. 

Adaptive management and monitoring designed to lead to greater understanding 

of any of these areas would greatly facilitate our management goals of conserving 

ecosystem processes and functions while providing recreation opportunities (see 

“Monitoring and Adaptive Management” on page 51). 
13

The following sections of this document are designed to provide managers with some 

tools that can be used to evaluate wildlife habitats for various focal wildlife species. 

In addition, a framework for how to approach adaptive management and monitoring 

is provided. This information will help address the mutual goals of conserving wildlife 

species while providing recreation opportunities. These goals have many commonalities, not the least of which is the desire of people to experience “wildlife” during their 

recreational outings. 

There were nine wildlife species that were included in the wide-ranging carnivore 

group (see app.). The species that met the criteria of a focal species for this group 

included the grizzly bear (Ursus arctos), Canada lynx (Lynx canadensis), gray wolf 

(Canis lupus) and wolverine (Gulo gulo). These four species were representative of 

the habitat requirements of the other species in the group and were sensitive to an 

array of road- and trail-associated factors. In addition, three of these species are 

federally listed, and the other, wolverine, has been petitioned (Biodiversity Legal 

Foundation 2000) for listing and is under review. 

Mammalian carnivores have responded variously to human recreation. Some species, 

such as coyotes, have adapted to the presence of humans and to human activities 

(Crabtree and Sheldon 1999). For others, human recreational activities are documented or suspected to have significant adverse impacts (Claar et al. 1999). Because they 

are listed under the Endangered Species Act and have been the subjects of considerable research, evidence of such impacts is most compelling for grizzly bears and gray 

wolves (Claar et al. 1999). For several other carnivore species, such as black bear 

(Ursus americanus), mountain lion or cougar (Felis concolor, now Puma concolor), 

lynx, bobcat (Lynx rufus), wolverine, fisher (Martes pennanti), and marten (Martes 

americana), research has been focused on the demographic effects of hunting or 

trapping and not on the effects of other recreational activities on their habitats. 

Several studies have documented displacement of grizzly bears from trails (motorized 

and nonmotorized) and roads (Archibald et al. 1987; Kasworm and Manley 1990; Mace 

and Waller 1996, 1998; Mace et al. 1996, 1999; Mattson et al. 1987; McLellan and 

Shackleton 1988, 1989) (table 4). Factors related to human access include increased 

potential for poaching, collisions with vehicles, and chronic negative human interactions at campgrounds and campsites that are accessed by roads and trails (Claar et 

al. 1999, Wisdom et al. 2000) (table 4). Winter recreational activities have been documented to disturb bears in winter dens (Jonkel 1980, Linnell et al. 2000, Reynolds et 

al. 1986) and are of special concern if they occur within 200 m of a den site (Linnell et 

al. 2000). However, because we could not model grizzly bear denning habitat at this 

broad scale, project-level analyses should consider the direct and indirect effects of 

winter recreational activities in areas where grizzly bear denning is an issue. Finally, 

grizzly bear mortalities as a result of collisions with vehicles have been documented 

(Gibeau and Heuer 1996) (table 4). 

Few studies have been conducted on the effects of recreational activities on lynx 

(Ruediger et al. 2000). Other focal carnivores appear to be more sensitive to the 

effects of roads and trails (McKelvey et al. 2000); therefore, lynx was selected as a 

focal species because of concerns about the potential effects of winter recreational 

activities (Buskirk 1999, Koehler and Aubry 1994, Ruediger et al. 2000). Specifically, 

snow compaction associated with grooming for snowmobiling and cross-country 

skiing may provide travel routes for competitors and predators such as coyotes 

(Canis latrans), bobcats, and mountain lions (Buskirk 1999, Koehler and Aubry 1994, 

Wide-Ranging 

Carnivore Habitat 

Assessment 

Introduction and Focal 

Species Selection

Summary of Recreation 

Route-Associated 

Factors for Focal 

Species
14

Ruediger et al. 2000) (table 4). Other associated factors include disturbance of den 

sites during the period of rearing young (Claar et al. 1999) (table 4), which is a sitespecific issue that should be addressed during project-level analysis and planning. 

Lynx mortalities associated with collisions with vehicles have been documented on 

other areas (Gibeau and Heuer 1996). 

Gray wolves and wolverines are sensitive to road-associated factors but are not particularly affected by summer recreation trails (Banci 1994, Boyd and Pletscher 1999, 

de Vos 1948, Mech et al. 1988, Paquet and Callahan 1996, Thurber et al. 1994) (table 

4). For gray wolves, both Mech et al. (1988) and Thiel (1985) found that when road 

densities exceed about 1.6 km/0.9-km-radius circle (1 mi/mi2), wolves avoided or 

were displaced from areas. Mladenoff et al. (1995) found road density to be the major 

Table 4—Road- and recreation trail-associated factors for wide-ranging carnivores

Focal 

species

Road-associated 

factors

Motorized trailassociated factorsNonmotorized trailassociated factorsSnowmobile routeassociated factorsSki trail-associated 

factors

Grizzly 

 bear a

Poaching

Collisions

Negative human 

 interactions

Displacement or 

 avoidance

Poaching

Negative human 

 interactions

Displacement or

 avoidance

Poaching

Negative human 

 interactions

Displacement or 

 avoidance

Disturbance at a 

 specific site

Disturbance at a 

 specific site

Lynx b Down log reduction

Trapping

Collisions

Disturbance at a

 specfic site

Disturbance at a 

 specific site

Trapping

Disturbance at a 

 specific site

Route for competitors 

 or predators

Trapping

Disturbance at a 

 specific site

Route for competitors 

 or predators

Disturbance at a 

 specific site

Gray 

 wolf c

Trapping

Poaching

Collisions

Negative human 

 interactions

Disturbance at a 

 specific site

Displacement or 

 avoidance

Trapping

Disturbance at a 

 specific site

Trapping

Disturbance at a 

 specific site

Trapping

Physiological response

Wolverine d Down log reduction

Trapping

Disturbance at a 

 specific site

Collisions

Trapping

Disturbance at a 

 specfic site

Trapping

Disturbance at a 

 specific site

Trapping

Disturbance at a 

 specific site

Trapping

Disturbance at a 

 specific site

aSources: Archibald et al. 1987; Claar et al. 1999; Hood and Parker 2001; Jonkel 1980; Kasworm and Manley 1990; Linnell et al. 2000; Mace 

and Waller 1996, 1998; Mace et al. 1996, 1999; Mattson et al. 1987; McLellan and Shackleton 1988, 1989; Puchlerz and Servheen 1998; 

Weaver et al. 1987; Wisdom et al. 2000.

bSources: Banci 1994, Buskirk 1999, Claar et al. 1999, Koehler and Aubry 1994, McKelvey et al. 2000, Ruediger et al. 2000.

cSources: Boyd and Pletscher 1999; Claar et al. 1999; Creel et al. 2002; De Vos 1948; Harrison and Chapin 1998; Jensen et al. 1986; 

Mech et al. 1988, 1991; Mladenoff and Sickley 1998; Mladenoff et al. 1995, 1997; Thiel 1985; Thurber et al. 1994.

dSources: Banci 1994, Claar et al. 1999, Copeland 1996, Hornocker and Hash 1981, Koehler and Aubry 1994.
15

Assessment Processes 

for Focal Species 

predictor of wolf pack location. Jensen et al. (1986) reported that road densities >0.6 

km/km2 were apparent barriers to wolf dispersal. In Yellowstone, Voyageurs, and Isle 

Royale National Parks, Creel et al. (2002) found levels of stress hormones in wolves to 

be higher in areas with snowmobiles than in areas without snowmobiles. The implications of these elevated levels of stress hormones to gray wolf population dynamics are 

not currently well understood. Gray wolves have been documented to abandon den 

sites if disturbed by humans (Mech et al. 1991) (table 4). However, it was not possible to identify potential wolf denning habitat at the broad scale for this assessment, 

although it should be addressed at the project level. Both wolves and wolverines have 

been documented to be killed by collisions with vehicles (Gibeau and Heuer 1996, 

Paquet and Callahan 1996) (table 4). 

Winter recreational activities may displace wolverines from important natal dens in 

subalpine cirques (Copeland 1996, Hornocker and Hash 1981) (table 4). The effects 

of recreation trails on potential wolverine denning habitat will be addressed in this assessment process because of the ability to model potential denning habitat by using 

GIS (Copeland 1996). 

Grizzly bear assessment model—Cumulative effects models have been developed 

for grizzly bears (Gibeau 1998, Hood and Parker 2001, Puchlerz and Servheen 

1998, Weaver et al. 1987). The model we recommend for use on the Wenatchee and 

Okanogan National Forests (Puchlerz and Servheen 1998) identifies areas of relatively low human use, called core areas, which provide refugia for grizzly bears, within 

bear management units (BMUs). The BMUs have been identified for the portion of 

the Okanogan and Wenatchee National Forests within the grizzly bear recovery zone 

(USFWS 1997). These areas are generally large enough to provide a variety of seasonal habitats, making them appropriately sized to address cumulative effects. 

Core areas are identified by buffering high-use trails and open roads by 500 m on 

each side. The 500-m buffer was based on a considerable body of research that 

shows displacement of grizzly bears from habitats adjacent to roads and high-use 

trails (Kasworm and Manley 1990, Mace and Waller 1996, Mace et al. 1996, Mattson 

et al. 1987, McLellan and Shackelton 1988) (table 5) and has been used in other 

cumulative effects models (Hood and Parker 2001, Puchlerz and Servheen 1998). 

Definitions of high-use trails and open roads are provided in table 6. To use this model, roads and trails must be assigned attributes by using these definitions and linked to 

GIS for spatial analysis. 

This model should be applied to assess the effects of roads and recreation trails on 

grizzly bear habitat on a seasonal basis. Seasons appropriate to the Okanogan and 

Wenatchee National Forests are early-season—15 March or den emergence to 31 

May; middle season—1 June to 15 July; and late season—July 16 to 31 October or 

den entrance (NCETT 1999). Outputs of this model include (1) the amount of core 

area within the analysis area, (2) the vegetation types that are represented within the 

core areas, (3) the effects of trails on the amount of core area, and (4) the effects of 

roads on the amount of core area. 

Once the amount of core area has been determined for the BMU or subbasin influenced by the proposed project, then a relative rating of the level of influence of human 

activities on grizzly bear habitat can be made. The relative scale is as follows: <55 

percent core area = high level of human influence on the habitat, 55 to 70 percent core 

area = moderate level of human influence on the habitat, and >70 percent core area 

= low level of human influence on the habitat. These levels of core area are similar to 
16

what has been prescribed in other areas where grizzly bears and human access are 

being managed, and provide reasonable estimates of cumulative effects thresholds 

(Gibeau 1998, Hood and Parker 2001, Puchlerz and Servheen 1998, USFWS 1993). 

Canada lynx assessment model—We have a rudimentary understanding of the 

effects of recreational activities on Canada lynx (Ruediger et al. 2000). Canada lynx 

were selected as a focal species to address the potential for snowmobiling and ski 

trails to provide routes for competitors such as coyotes, bobcats, and cougars to 

access lynx habitat (Buskirk 1999, Koehler and Aubry 1994). For lynx, which have 

relatively narrow habitat preferences (Koehler 1990, McKelvey et al. 2000), lynx 

analysis units (LAUs) have been identified. These areas have been identified with 

adequate suitable habitat to support resident lynx (Ruediger et al. 2000) and are an 

appropriate spatial scale for addressing cumulative effects. 

To assess the effects of recreational activities on lynx habitat, the density of groomed 

or commonly used snowmobile routes and ski trails should be determined by using 

LAUs as the area of analysis. Determine the density of groomed ski and snowmobile 

routes in an LAU by using current GIS data layers for spatial analysis. The outputs of 

this analysis include the proportion of the LAU with route density <1.6 km/0.9-kmradius circle (<1 mi/mi2), 1.6 to 3.2 km/0.9-km-radius circle (1 to 2 mi/mi2), and 

>3.2 km/0.9-km-radius circle (>2 mi/mi2). 

Table 5—Effects of roads and trails on grizzly bears and gray wolves

 Distance at which use Road density at which

Human activity Focal species is less than expected a use is less than expected b References

 Kilometers per

 Meters square kilometer

Roads Grizzly bear 500 Mattson et al. 1987

Roads Grizzly bear 100 McLellan and Shackleton 1988

Roads Grizzly bear 200 through spring Aune and Kasworm 1989

 100 through summer

 400 through autumn

Roads Grizzly bear 914 Kasworm and Manley 1990

Roads Grizzly bear 500 Mace et al. 1996

Roads and trails Grizzly bear 500 Hood and Parker 2001

Trails Grizzly bear 813 through spring Mace and Waller 1996

 878 through summer

 1,129 through autumn

Trails Grizzly bear 122 through spring and fall Kasworm and Manley 1990

Roads Gray wolf 0.7 Harrison and Chapin 1998

Roads Gray wolf .4 Mladenoff et al. 1995

Roads Gray wolf .6 Mech et al. 1988

Roads Gray wolf .7 Thiel 1985

Roads Gray wolf .6 Jensen et al. 1986

aDistance from a linear recreation route in which use by an animal was statistically significantly less than expected.

bDensity of roads at which use by an animal was statistically significantly less than expected.
17

Table 6—Definitions of roads and trails used in the core area analysis to determine the level of influence of 

road and recreation trails on grizzly bear habitat

Road or trail type Definition Effect to core area

Impassable roads Roads not reasonably or prudently passable by 

 conventional four-wheeled passenger vehicles, 

 motorcycles, or all-terrain vehicles

Any road classified as impassable during a 

 bear analysis season would be included as 

 core area for that season. 

Restricted roads Roads that are restricted with gates or berms but 

 receive occasional administrative use

Any road classified as restricted during a bear 

 analysis season would be included as core 

 area for that season.

Open roads Roads open to motorized use during any portion 

 of an active bear season, or information is not 

 available to verify the effectiveness of a gate or 

 berm

Any road classified as open during a bear 

 analysis season would not be included as 

 core area for that season.

Open motorized trail Trails that are passable by motorcycles or all-

 terrain vehicles and are not legally restricted

Any trail classified as open motorized during a 

 bear analysis season would not be included 

 as core area for that season.

Open nonmotorized rail Trails that are not reasonably or prudently 

 passable by motorcycles or all-terrain vehicles, 

 but are not legally restricted, or any trail that is 

 legally restricted to allow only nonmotorized use

Any trail classified as open nonmotorized 

 during a bear analysis season would be 

 included as core area for that season unless 

 it is a high-use trail.

High-use trail Any nonmotorized trail that receives an average 

 of 20 or more parties per week during the grizzly 

 bear season being assessed

Any trail categorized as high use during a 

 season would not be included as core area for 

 that season.

Based on the above information, the relative level of human influence on lynx habitat 

can then be rated. The rating scheme is as follows: <25 percent of the LAU with ski 

and snowmobile route densities of <1.6 km/0.9-km-radius circle (<1 mi/mi2) = low level 

of human influence on lynx habitat, >25 percent with route densities 1.6 km/0.9-kmradius circle (>1 mi/mi2) to 3.2 km/0.9-km-radius circle (2 mi/mi2) = a moderate level 

of human influence on lynx habitat, and >25 percent with route densities >3.2 km/0.9-

km-radius circle (>2 mi/mi2) = a high level of human influence on lynx habitat. This rating scheme is intended to provide a means of making comparisons among the relative 

levels of human influence within LAUs. Additional research is needed to determine 

how increases in groomed ski and snowmobile route density affect lynx habitat use 

and to define cumulative effects thresholds. 

Gray wolf and wolverine assessment model—An assessment of the effects of 

roads and trails on gray wolves and wolverines should be based on an area that approximates their extensive home ranges (Banci 1994, Boyd et al. 1995, Mech 1970). 

Therefore, to address cumulative effects, BMUs should be used for assessments 

within the grizzly bear recovery zone and 4th-field subbasins for areas outside of the 

grizzly bear recovery zone. 

To address the road- and trail-associated factors identified for gray wolves and wolverines (table 4), three analyses should be conducted to assess the cumulative effects. 

These include an assessment of the current level of road and motorized trail access 

within available habitat, the effects of snowmobile routes and ski trails that occur on 

deer and elk winter ranges (see “Ungulate Winter and Summer Habitat Assessment”), 
18

and the effects of snowmobile routes and ski trails on potential wolverine denning habitat. No model is currently available to predict wolf denning habitat on the Okanogan 

and Wenatchee National Forests. 

A moving windows road and motorized trail density analysis using a 0.9-km-radius 

circular window should be used to classify areas as follows: areas with no open roads 

or motorized trails, areas with densities from >0 to 1.6 km/0.9-km-radius circle (>0 to 

1.0 mi/mi2), and areas with densities that are >1.6 km/0.9-km-radius circle (>1 mi/mi2) 

within a 4th-field subbasin or a BMU. Outputs of this model for each BMU or subbasin 

include (1) the amount and location of areas with no open roads or motorized trails, (2) 

the amount and location of areas with open road and motorized trail densities >0 to 1.6 

km/0.9-km-radius circle (>0 to 1.0 mi/mi2), and (3) the amount and location of areas 

with open road and motorized trail densities >1.6 km/0.9-km-radius circle (>1 mi/mi2). 

Areas with open road densities <1.6 km/0.9 km (<1 mi/mi2) are referred to as security 

habitats.

Based on the above information, the relative level of human influence on gray wolf 

and wolverine habitat can then be rated. The rating scheme we used was <50 percent 

of a BMU or subbasin in security habitat = a high level of human influence on wolf and 

wolverine habitat, 50 to 70 percent security habitat = a moderate level of human 

influence on wolf and wolverine habitat, >70 percent security habitat = a low level of 

human influence on wolf and wolverine habitat. 

Potential wolverine denning habitat—The effects of snowmobile routes and ski 

trails on potential wolverine denning habitat could be assessed by using the following model. Current GIS data layers with snowmobile routes and ski trails would be 

overlaid onto the land type associations (LTAs) (USDA FS 2000a) that correspond to 

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

(Copeland 1996). These include LTAs Ha7, Ha8, Hb9, and Hi9. The density of snowmobile and ski trails would then be calculated for the potential denning habitat located 

within a BMU or subbasin. The outputs of this model include potential wolverine denning habitat with groomed winter route densities >1.6 km/0.9-km-radius circle (>1 mi/

mi2), and areas with densities >3.2 km/0.9-km-radius circle (>2 mi/mi2). 

A relative rating of the level of influence of winter recreation routes on potential wolverine denning habitat can then be made by using the following scale. A high level of 

human influence on potential wolverine denning habitat = >25 percent of the potential 

habitat within a BMU or subbasin with winter route densities >3.2 km/0.9-km-radius 

circle (>2 mi/mi2), a moderate level of human influence = >25 percent of the potential 

habitat within a BMU or subbasin with winter route densities >1.6 km/0.9-km-radius 

circle (>1 mi/mi2) and <3.2 km/0.9-km-radius circle (<2 mi/mi2), and a low level of 

human influence = <25 percent of the potential denning habitat within a BMU or subbasin with winter route densities >1.6 km/0.9-km-radius circle (>1 mi/mi2). 

Research is needed to validate the applicability of the bear and wolf models for use 

on the Okanogan and Wenatchee National Forests as they are based on research 

conducted in other ecosystems. Specifically, the response of grizzly bears and gray 

wolves to different levels of human use on trails and roads needs further study (Claar 

et al. 1999). Research needs to be conducted to determine the direct and indirect 

effects of recreation on wolverines (Banci 1994) and lynx (Koehler and Aubry 1994, 

Information Gaps and 

Research Needs
19

Ruediger et al. 2000), including how snow compaction alters interference competition among lynx, bobcats, and coyotes (Koehler and Aubry 1994). The results of this 

research could then be used to adapt the assessment models. 

Habitat-effectiveness monitoring—Periodic application of the assessment models 

for wide-ranging carnivores across the Okanogan and Wenatchee National Forests 

would establish baseline conditions and allow comparisons of habitat effectiveness 

over time. Information on road and trail status and use levels should be updated at 

the project level and fed into a forest-wide GIS for landscape-scale assessment. 

Monitoring information can then be used to guide adaptive ecosystem management as 

new science becomes available about the interactions between wide-ranging carnivores and recreation. 

Population-level monitoring—Presently, the numbers of grizzly bears, gray wolves, 

and wolverines may be too low (Almack et al. 1993; Gaines et al. 1995, 2000a, 

2000b) to effectively monitor their populations. Lynx on the Okanogan National Forest 

could provide a situation where numbers are high enough for population monitoring. 

Population monitoring methods for lynx are currently being developed and implemented (McKelvey et al. 1999). 

There are six wildlife species included in the ungulate group: mule deer (Odocoileus 

hemionus), white-tailed deer (O. virginianus), elk (Cervus elaphus), moose (Alces alces), bighorn sheep (Ovis canadensis), and mountain goats (Oreamnos americanus). 

The focal species selected to represent the effects of roads and recreational activities 

on ungulates include mule deer, elk, bighorn sheep, and mountain goats. These species were selected because their habitat needs and response to recreation trails and 

roads were representative of the group, and because habitat effects are possible to 

monitor. Additionally, the bighorn sheep is listed as a “sensitive” species. 

In general, ungulates respond to recreational activities by avoiding areas near roads, 

recreation trails, and other types of human activities (tables 7 and 8) (Cassier et al. 

1992, Ferguson and Keith 1982, Freddy et al. 1986, Leslie and Douglas 1980, 

MacArthur et al. 1982, Papouchis et al. 2001, Rowland et al. 2000). Human activities 

are of particular concern for ungulates when they occur on their winter ranges or 

where young are reared (Canfield et al. 1999). The direct and indirect effects of 

recreation on rearing areas may be best evaluated at the site-specific project level 

owing to the difficulty in identifying them at the broad scale of this assessment. 

Several studies have been conducted on the effects of linear recreation routes on 

mule deer. For example, ski trails seem to displace mule deer to greater distances 

than occurs along snowmobile routes (table 8) (Cassier et al. 1992, Freddy et al. 

1986). Freddy et al. (1986) reported that mule deer displacement by skiers was independent of skier numbers or group size. Perry and Overly (1977) showed that deer 

were displaced up to 800 m from roads. 

Elk responded to persons on foot by moving away from trails, and the distance of this 

displacement was quite variable among study areas (Cassier et al. 1992, Ferguson 

and Keith 1982, Schultz and Bailey 1978) (table 8). Elk moved away from ski trails 

only when use was >8 persons per day (Ferguson and Keith 1982). Creel et al. (2002) 

reported elevated levels of stress hormones in elk in Yellowstone National Park when 

they were exposed to snowmobile activity. In addition, Millspaugh et al. (2001) reported that increased levels of stress hormones were associated with vehicle use on 

Monitoring and Adaptive 

Management 

Ungulate Winter and 

Summer Habitat 

Assessment 

Introduction and Focal 

Species Selection

Summary of Recreation 

Route-Associated 

Factors for Focal 

Species
20

Table 7—Road- and recreation trail-associated factors for ungulate focal species

Focal 

species

Road-associated 

factors

Motorized trailassociated factorsNonmotorized trailassociated factorsSnowmobile routeassociated factorsSki trail-associated 

factors

Mule deer a Hunting

Poaching

Collisions

Displacement or 

 avoidance

Disturbance at a

 specific site

Hunting

Poaching

Displacement or 

 avoidance

Disturbance at a

 specific site

Hunting

Poaching

Displacement or 

 avoidance

Disturbance at a

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a

 specific site

Elk b Hunting

Poaching

Collisions

Displacement or 

 avoidance

Disturbance at a

 specific site

Hunting

Poaching

Displacement or 

 avoidance

Disturbance at a 

 specific site

Hunting 

Poaching

Displacement or 

 avoidance

Disturbance at a

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Physiological 

 response

Displacement or 

 avoidance

Disturbance at a

 specific site

Bighorn 

 sheep c

Hunting

Poaching

Collisions

Displacement or 

 avoidance

Disturbance at a

 specific site

Physiological 

 response

Hunting

Poaching

Displacement or 

 avoidance

Disturbance at a

 specific site

Hunting 

Poaching

Displacement or 

 avoidance

Disturbance at a

 specific site

Displacement or 

 avoidance

Disturbance at a

 specific site

Physiological 

 response

Displacement or 

 avoidance

Disturbance at a

 specific site

Mountain 

 goat d

Hunting

Poaching

Collisions

Displacement or 

 avoidance

Disturbance at a

 specific site

Movement barrier 

 or filter

Hunting

Poaching

Hunting

Poaching

a Sources: Canfield et al. 1999, Cassier et al. 1992, Freddy et al. 1986, Johnson et al. 2000, Ward et al. 1980.

b Sources: Canfield et al. 1999, Cassier et al. 1992, Cole et al. 1997, Creel et al. 2002, Ferguson and Keith 1982, Johnson et al. 2000, Lyon 

1983, Millspaugh et al. 2001, Phillips and Alldredge 2000, Roloff 1998, Roloff et al. 2001, Rowland et al. 2000, Schultz and Bailey 1978, Ward 

1976, Ward et al. 1980.

c Sources: Canfield et al. 1999; 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.

d Sources: Joslin 1986, Pedevillano and Wright 1987, Singer 1978, Singer and Doherty 1985.
21

Table 8—Displacement distances and mean distance from roads reported for ungulate focal species

Human activity Focal species Distance displaceda Mean distanceb References

- - - - - - - - - - - - - - Meters - - - - - - - - - - - - - -

Hiking Mule deer 191 Freddy et al. 1986

Snowmobiling Mule deer 133 Freddy et al. 1986

Hiking Mule deer 200 Ward et al. 1980

Hiking Elk 86 Schultz and Bailey 1978

Skiing Elk 650 Cassier et al. 1992

Skiing Elk Moved away from

high-use (>8 persons

per day) trail

Ferguson and Keith 1982

Hiking Bighorn sheep 50 MacArthur et al. 1982

Hiking Bighorn sheep Did not affect 

sheep movements

Hicks and Elder 1979

Hiking Bighorn sheep 200 at which sheep

first responded

Papouchis et al. 2001

Roads and trails 

 <500 visitors per year

Bighorn sheep 100 Smith et al. 1991

Roads and trails 

 >500 visitors per year

Bighorn sheep 150 Smith et al. 1991

Road driving 

 <1 vehicle per day

Bighorn sheep 354 Papouchis et al. 2001

Road driving 

 5 to 13 vehicles per day

Bighorn sheep 490 Papouchis et al. 2001

Road driving Elk 400 Ward 1976

Road driving Mule deer 800 Perry and Overly 1977

Road driving (closed to 

 vehicles but open to 

 all-terrain vehicles)

268 to 280 Johnson et al. 2000

Road driving (low traffic 

 0 to 1 vehicle per 12 hours)

Elk 869 to 890 Johnson et al. 2000

Road driving (medium traffic 

 2 to 4 vehicles per 12 hours)

Elk 909 to 1032 Johnson et al. 2000

Road driving (high traffic 

 >4 vehicles per 12 hours)

Elk 1103 to 1560 Johnson et al. 2000

a Average distance at which animals reacted to human activities and were displaced from the area.

b Distance that radio-collared animals were located from roads.

primary roads and the density of primary roads. Presently, the relationship between 

stress hormones and population dynamics of elk is not well understood, and these results should be interpreted with caution (Millspaugh et al. 2001). Johnson et al. (2000) 

showed that as the volume of traffic increased on roads, the mean distance that elk 

were located from roads also increased (table 8). Hayes et al. (2002) reported that 

mortality of elk during hunting season increased when total road density increased. 

In addition, elk reproductive success has been shown to decrease following human 
22

disturbance to calving areas (Phillips and Alldredge 2000). Cole et al. (1997) showed 

that road closures are successful in reducing the effects of habitat displacement and 

increasing elk survivorship. 

Bighorn sheep also 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) (table 8). MacArthur et al. (1979) 

showed that the heart rate of bighorn sheep varies inversely with distance from a road. 

MacArthur et al. (1982) reported that sheep are affected by a human approaching 

within 50 m, and Papouchis et al. (2001) found that bighorn sheep respond to hikers 

at an average distance of 200 m. They also showed that avoidance of roads is greater 

for high-use (5 to 13 vehicles per hour) versus low-use (1 vehicle per hour) roads. On 

average, radio-collared sheep were 490 m from high-use roads compared to 354 m 

from low-use roads (Papouchis et al. 2001). Smith et al. (1991) developed a habitat 

suitability model for bighorn sheep and considered areas within 100 m of low to moderate human use (<500 visitors per year) trails and roads as unsuitable, and areas 

within 150 m of high human use (>500 visitors per year) trails and roads as unsuitable. 

Limited research has been conducted on the effects of recreational activities on 

mountain goats, although concern has been expressed about the interactions between recreation and goats (Sachet 1988). Highways have been documented to cause 

difficulty for crossing goats, resulting in avoidance or temporary displacement (Singer 

1978, Singer and Doherty 1985). People walking on the highway to observe goats increased goat crossing time and altered crossing routes (Pedevillano and Wright 1987). 

In Montana’s Rocky Mountain front, mountain goat reproduction was lower in a herd 

exposed to human activity (ski area, energy exploration, developed recreation), compared to a herd in a more remote area (Joslin 1986). No studies on the effects of forest 

roads or recreation trails were found in this review. Rodrick and Milner (1991) recommended that recreational activities (roads and hiking trails) that occur within 1.6 km of 

winter ranges from 1 November to 30 June be evaluated. 

Mule deer and elk winter habitat disturbance index—The cumulative effects of 

roads and recreation trails on mule deer and elk should be assessed during winter 

when disturbance has the potential to be the most detrimental (Canfield et al. 1999). 

This means evaluating the effects of roads, ski trails, and snowmobile routes on the 

winter ranges for these species. Winter ranges for mule deer and elk on the Okanogan 

and Wenatchee National Forests generally occur at lower elevations and are usually 

distinct units separated by private lands and higher elevation nonwinter habitats. To 

address cumulative effects, the entire unit of winter range habitat should be evaluated, 

and the area should be at least 800 to 1200 ha (Lyon 1983). 

An index of habitat effectiveness applied to the winter range habitat unit can be calculated by using GIS with current data layers showing plowed roads, ski trails, and 

snowmobile routes. Because of the differing effects of these activities, different buffers would be applied to each to evaluate the amount of affected habitat. For roads, 

the zone of influence would be 800 m on each side of a plowed road; for ski trails that 

receive use >8 persons per day, the zone of influence would be 200 m on each side; 

and for snowmobile routes, the zone would be 150 m on each side of the route. The 

zone of influence may be modified based on the topography adjacent to the linear 

recreation route. The proportion of the winter range that is influenced by winter recreation is determined. Model outputs include the proportion of winter range influenced by 

roads, ski trails, and snowmobile routes. 

Assessment Processes 

for Focal Species
23

The summed relative effects of these activities are then rated by using the following 

scale: >70 percent of the winter range outside of a zone of influence rates as a low 

level of human influence on deer and elk winter range, 50 to 70 percent of the winter 

range outside of a zone of influence is classified as a moderate level of human influence, and <50 percent outside of the zone of influence rates as a high level of human 

influence. 

Bighorn sheep summer or winter habitat disturbance index—To assess the effects of road- and recreational trail-associated factors on bighorn sheep, a summer 

and winter range habitat-effectiveness index is calculated. To calculate this index, GIS 

maps of bighorn sheep winter and summer ranges are needed. For the winter index, 

GIS layers of current roads and their use levels, ski trails, and snowmobile routes are 

used. For the summer index, GIS layers of roads and their use levels, motorized trails, 

and nonmotorized trails are used. Roads that receive <1 vehicle per day and other 

motorized routes are buffered by a 350-m zone of influence and those with >1 vehicle 

per day a 500-m zone of influence (table 9). Groomed ski trails and hiking trails are 

buffered by 200 m on each side (table 9). The zone of influence may be modified 

based on the topography adjacent to the linear recreation route. The proportions of the 

summer and winter ranges that are influenced by road and trail recreation activities 

are then determined. Model outputs include the proportion of summer or winter range 

influenced by roads, the proportion of summer or winter range influenced by trails, and 

the proportion of summer or winter range influenced by motorized trail routes. 

The relative effects of these activities are then rated by using the following scale: 

>70 percent of the range outside of a zone of influence rates as a low level of human 

influence on bighorn sheep summer or winter range, 50 to 70 percent of the summer 

or winter range outside of a zone of influence is classified as a moderate level of 

human influence, and <50 percent outside of the zone of influence rates as a high 

level of human influence. 

Mule deer and elk summer habitat disturbance index—Previous generations of 

deer and elk habitat-effectiveness models have used road density as an index for 

summer ranges. However, Roloff (1998) and Rowland et al. (2000) suggested that a 

spatially explicit roads variable, based on distance to open roads, may be more appropriate. In addition, Johnson et al. (2000) showed that different levels of traffic can have 

different degrees of influence on deer and elk habitat use. Therefore, to evaluate the 

Table 9—The zone of influence applied to each side 

of a trail or road based on road type and use level 

for the bighorn sheep summer and winter habitat 

influence indices

Trail or road type and status Zone of influencea

Meters

Nonmotorized trail (ski or hiking) 200

Motorized trail 350

Road <1 vehicle per day 350

Road >1 vehicle per day 500

a Zone of influence distance may be modified by topographic features.
24

Table 10—The zone of influence applied to each 

side of a motorized trail or road based on road type 

and use level for the deer and elk summer habitat 

influence index

Trail or road type and status Zone of influencea

Meters

Motorized trails 300

Closed road (no vehicular traffic 

 but open to all-terrain vehicles) 300

Low traffic open road 

 (>0 to 1 vehicle per 12 hours) 900

Moderate traffic open road 

 (>2 to <4 vehicles per 12 hours) 1000

High traffic open road 

 (>4 vehicles per 12 hours) 1300

a Zone of influence distance may be modified by topographic features.

cumulative effects of road and motorized trails on deer and elk summer ranges, roads 

and motorized trails would be buffered by the distances shown in table 10. These buffers would be applied to all the roads in a 5th-field watershed, and the proportion of the 

habitat in the watershed would be determined. The zone of influence may be modified 

based on the topography adjacent to the linear recreation route. This becomes the 

portion of the watershed that is influenced by roads. This number is then divided by 

the total area in the watershed to estimate the percentage within a zone of influence. 

A relative ranking of the level of road and trail influences on deer and elk summer 

range is then applied as follows: >70 percent of the summer range outside of a zone of 

influence is ranked as a low level of human influence on deer and elk summer range, 

50 to 70 percent of the summer range outside of a zone of influence is ranked as a 

moderate level of human influence, and <50 percent outside of the zone of influence is 

ranked as a high level of human influence. 

Mountain goat winter habitat disturbance index—To assess the influence of 

recreation routes on mountain goats, two sources of information are needed for each 

5th-field watershed in which a project or related projects may occur. A map of mountain 

goat winter range is overlaid with roads, trails, snowmobile routes, and ski trails, and 

each is buffered by a 500-m zone of influence. The zone of influence may be modified 

based on the topography adjacent to the linear recreation route. The proportion of 

winter range outside a zone of influence is then determined for each watershed. A 

relative index is then applied: >70 percent of the range outside of a zone of influence 

is ranked as a low level of human influence on mountain goat winter range, 50 to 70 

percent of the winter range outside of a zone of influence is classified as a moderate 

level of human influence, and <50 percent outside of the zone of influence is ranked 

as a high level of human influence. 
25

Additional research is needed on the effects of roads and snowmobiles on bighorn 

sheep and mountain goats during winter. The most efficient method to accomplish 

this would be through the use of telemetry or observational studies conducted during 

winter. All ungulate focal species could benefit from research that links the effects of 

recreation trails and roads to the demography of the focal species. Research on this 

subject has been most intensively focused on elk, and other species would benefit 

from similar efforts. 

Habitat monitoring—Periodic application of the assessment models would allow 

trends of habitat effectiveness to be tracked over time. In addition, monitoring could 

be used to validate the zone of influence estimates with site-specific conditions (Roloff 

et al. 2001). This could be done by using radio-telemetry (White and Garrott 1990), 

snow tracking, or pellet group indices (Wemmer et al. 1996). 

Population monitoring—Population monitoring of ungulates is generally carried out 

by state agencies relying on aerial counts conducted during winter when animals are 

concentrated on their winter ranges. These data provide information on general trends 

of ungulate populations. 

A total of 71 species was included in the late-successional forest habitat species 

group (see app.). The focal species that were selected for this group include species 

associated with mixed-conifer late-successional forests such as the northern spotted 

owl (Strix occidentalis caurina), northern goshawk (Accipiter gentilis), brown creeper 

(Certhia americana), American marten, fisher, and the northern flying squirrel 

(Glaucomys sabrinus). Additional species were selected that are associated with 

old ponderosa pine (Pinus ponderosa Dougl. ex Laws.) forests and they include the 

pygmy nuthatch (Sitta pygmaea), white-breasted nuthatch (Sitta carolinensis), and 

white-headed woodpecker (Picoides albolarvatus). These species were selected 

because they represent an array of road- and recreation trail-associated factors, 

and late-successional habitats (table 11). 

There is limited information available concerning the effects of winter recreation routes 

on many of the wildlife species associated with late-successional habitats. More studies have documented the effects that roads and nonwinter recreation routes can have 

on these species. 

Northern spotted owls could be affected by the edge effects that roads can have 

when they fragment suitable habitat, or mortality as a result of collisions with vehicles 

(USDA FS 1997). In addition, linear recreation routes can result in physiological stress 

responses in owls and may result in displacement of owls by certain types of recreational activities. For example, Wasser et al. (1997) found that stress hormone levels 

were significantly higher in male northern spotted owls (but not females) when they 

were located <0.41 km from a major logging road compared to spotted owls in areas 

>0.41 km from a major logging road. The potential effects of elevated stress hormones 

on spotted owl population dynamics are not well understood. However, chronic high 

levels of stress hormones (corticosterone) may have negative consequences on reproduction or physical condition in birds (Marra and Holberton 1998). Additional evidence 

of recreation effects on spotted owls was reported by Swarthout and Steidl (2001) 

who found that the closely related Mexican spotted owl (Strix occidentalis lucida) was 

affected by hikers. They reported that juveniles and adults were unlikely to flush at 

distances ≥12 m and ≥24 m from hikers, respectively. Finally, although not a study of 

Information Gaps and 

Research Needs

Monitoring and Adaptive 

Management 

Late-Successional 

Forest Habitat 

Assessment 

Introduction and Focal 

Species Selection

Summary of Recreation 

Route-Associated 

Factors for Focal 

Species
26

Focal 

species

Road-associated 

factors

Motorized trailassociated factorsNonmotorized trailassociated factorsSnowmobile routeassociated factors

Ski trailassociated 

factors

Northern 

 goshawka

Edge effects

Habitat loss or 

 fragmentation

Disturbance at 

 specific site

Collection

Disturbance at a 

 specific site

Collection

Disturbance at a

 specific site

Collection

Northern 

 spotted owl b

Edge effects

Snag reduction

Disturbance at a

 specific site

Collisions

Physiological response

Disturbance at a

 specific site

Disturbance at a

 specific site

Brown 

 creeper c

Snag reduction

Edge effects

Displacement or 

 avoidance

Habitat loss or 

 fragmentation

Route for competitors 

 or predators

Route for 

 competitors or 

 predators

Displacement or 

 avoidance

Route for 

 competitors 

 or predators

Displacement or 

 avoidance

Route for competitors 

 or predators

Route for 

 competitors 

 or predators

American 

 marten d

Snag reduction

Down log reduction

Edge effects

Trapping

Collisions

Habitat loss or 

 fragmentation

Movement barrier 

 or filter

Trapping Trapping Trapping Trapping

Fisher e Snag reduction

Down log reduction

Edge effects

Trapping

Collisions

Habitat loss or 

 fragmentation

Movement barrier 

 or filter

Displacement or 

 avoidance

Trapping Trapping Trapping

Displacement or 

 avoidance

Trapping

Table 11—Road- and trail-associated factors for late-successional habitat-associated focal species
27

a Sources: Beier and Drennan 1997, Daw and DeStefano 2001, Erdman et al. 1998, Grubb et al. 1998, Hamann et al. 1999, Jones 1979, 

Reynolds et al. 1992, Wisdom et al. 2000.

b Sources: Delaney et al. 1999, Swarthout and Steidl 2001, USDA FS 1997, Wasser et al. 1997.

c Sources: Brand and George 2001, Foppen and Reijnen 1994, Gutzwiller et al. 2002, Hickman 1990, Hutto 1995, Keller and Anderson 1992, 

Miller et al. 1998.

d Sources: Buskirk and Ruggiero 1994; Claar et al. 1999; Powell 1979, 1982; Weaver 1993; Wisdom et al. 2000.

e Sources: Claar et al. 1999; Heinenmeyer and Jones 1994; Powell 1979, 1982; Rosenburg and Raphael 1986; Weaver 1993; Wisdom et al. 

2000.

f Sources: Carey 1991, 1995, 2000; Carey et al. 1997, 2002; Wisdom et al. 2000.

g Sources: Foppen and Reijnen 1994, Gutzwiller et al. 2002, Miller et al. 1998, Wisdom et al. 2000.

h Sources: Foppen and Reijnen 1994, Gutzwiller et al. 2002, Miller et al. 1998, Wisdom et al. 2000.

i Sources: Hamann et al.1999, Miller et al. 1998, Wisdom et al. 2000.

Focal 

species

Road-associated 

factors

Motorized trailassociated factorsNonmotorized trailassociated factorsSnowmobile routeassociated factors

Ski trailassociated 

factors

Northern flying 

 squirrel f

Snag reduction

Down log reduction

Edge effects

Habitat loss or 

 fragmentation

Movement barrier 

 or filter

Pygmy 

 nuthatch g

Snag reduction

Edge effects

Displacement or 

 avoidance

Displacement or 

 avoidance

Displacement or 

 avoidance

White-breasted 

 nuthatch h

Snag reduction

Edge effects

Displacement or 

 avoidance

Displacement

 or avoidance

Displacement or 

 avoidance

White-headed 

 woodpecker i

Snag reduction

Edge effects

Table 11—Road- and trail-associated factors for late-successional habitat-associated focal species 

(continued)

recreational effects, Delaney et al. (1999), studied the effects of chainsaw and helicopter noise on Mexican spotted owls. They found that no spotted owls flushed when 

noise stimuli were >105 m away. This study further shows that spotted owls may be 

sensitive to some types of noise disturbance. 

Some types of human disturbances to goshawk nests have been a suspected 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). Grubb et al. 

(1998) reported that vehicle traffic from roads caused no discernable behavioral 

response by goshawks at distances >400 m from nest sites in forested habitats with 

noise levels <54 decibels. Critical times for human disturbance to be evaluated include 

the nesting period and postfledgling periods for goshawks. The postfledgling area is 
28

an area of concentrated use from the time the young leave the nest until they are no 

longer dependent on the adults for food. Jones (1979) recommended a 400- to 500-m 

radius buffer around goshawk nest sites to protect them from disturbance during 

1 March to 30 September. Forest road-associated factors include the fragmentation 

or loss of goshawk habitat as a result of roads, or more likely, road networks (Wisdom 

et al. 2000). Goshawks have been shown to be sensitive to changes in canopy closure 

and habitat fragmentation (Beier and Drennan 1997, Daw and DeStefano 2001) such 

as could result from a road network. 

Recreation routes have been shown to affect forest birds. For example, roads may 

result in the loss or fragmentation of habitat for brown creepers (table 11). Hutto (1995) 

found that brown creepers were twice as likely to occur in habitats that were more 

than 100 m from a road, and both Keller and Anderson (1992) and Brand and George 

(2001) found that brown creepers were associated with larger forest patches. Foppen 

and Reijnen (1994) found that roads and motorized trails reduced forest bird reproduction up to a distance of 200 m. In addition, roads and recreation trails may break up 

forest patches and increase nest predation and parasitism rates by species such as 

cowbirds (Molothrus spp.) (Hickman 1990, Miller et al. 1998). Gutzwiller et al. (2002) 

found that human intrusion, in the form of hiking, increased the probability of gray jay 

(Perisoreus canadensis) recurrence, which may increase nest predation on other bird 

species. Trails used for hiking also can influence forest bird habitat use. Miller et al. 

(1998) reported a zone of influence of 100 m for some forest bird species. 

Fisher and marten are known for their vulnerability to trapping and susceptibility to 

overharvest (Heinenmeyer and Jones 1994; Powell 1979, 1982; Weaver 1993). Roads 

and trails, especially snowmobile trails, developed for recreation also are used by trappers and, therefore, increase vulnerability of these species to trapping mortality (Claar 

et al. 1999). Other road- and trail-associated factors included snag and downed log 

reduction, edge effects, collisions, and habitat loss or fragmentation (table 11) (Buskirk 

and Ruggiero 1994, Claar et al. 1999, Rosenberg and Raphael 1986, Wisdom et al. 

2000). 

Northern flying squirrels play important ecological roles in late-successional forests 

(Carey 1991, 1995) and are therefore included as a focal species. The road-associated factors for the northern flying squirrel included snag and downed log reduction, edge effects, and habitat loss or fragmentation (table 11) (Wisdom et al. 2000). 

Several studies have shown that forest management can influence den site availability 

(Carey et al. 1997), food abundance (Carey et al. 2002), and northern flying squirrel densities (Carey 2000). Presumably, roads, and especially road networks, could 

have similar influences. No trail-associated factors were identified in the literature we 

reviewed. 

Pygmy nuthatch, white-breasted nuthatch, and white-headed woodpecker are affected 

by the removal of snags along roads for firewood and safety, and the edge effects of 

roads to their habitats (table 11) (Wisdom et al. 2000). No recreation trail-associated 

factors were identified for white-headed woodpeckers (Hamann et al. 1999). Roads 

and recreation trails may influence pygmy nuthatch and white-breasted nuthatch habitat use (Miller et al. 1998). For example, Foppen and Reijnen (1994) found that roads 

and motorized trails influenced forest bird reproduction to a distance of 200 m. Miller 

et al. (1998) reported a zone of influence of 75 to 100 m along trails used for hiking for 

some forest bird species 
29

Habitat for late-successional-associated species within the range of the northern spotted owl is managed within a network of reserves (USDA FS 1994). On the Wenatchee 

and Okanogan National Forests, these reserves are called late-successional reserves 

(LSRs) and managed late-successional areas (MLSAs). This network of reserves was 

designed to provide for the viability of late-successional species (Thomas et al. 1993). 

When projects are proposed within one of these reserves, the cumulative effects 

of roads and trails on habitat effectiveness within the reserve should be assessed 

(USDA FS 1997). Reserves should be at least 4000 ha to adequately address cumulative effects. Reserves smaller than this can be grouped by including adjacent reserves 

until an adequately sized area is reached. Projects that are not located in a reserve 

but could affect late-successional habitats and species should be addressed by using 

late-successional habitat within a 5th-field watershed as the analysis area. 

In the Wenatchee National Forest LSR assessment (WNFLSRA), two indices to assess habitat effectiveness within LSRs and MLSAs were identified (USDA FS 1997). 

These included the overall open road density within the LSR and the amount of security habitat. Security habitat was defined as areas that were greater than 500 m from an 

open road. The WNFLSRA did not consider the effects of recreation trails within LSRs 

and MLSAs on habitat effectiveness for late-successional species. However, as a result of this review, the assessment model that is described below includes recreation 

trails, both winter and nonwinter, and should be viewed as an update to the security 

habitat model originally developed in the WNFLSRA (USDA FS 1997). 

Late-successional nonwinter habitat influence index—The assessment process 

to evaluate roads and recreational trails on habitat effectiveness for late-successional 

species should be divided into winter and nonwinter periods. For the nonwinter period, a habitat influence index and security habitat index should be calculated for the 

late-successional habitat in an LSR, MLSA, or 5th-field watershed in which the project 

is located. The habitat influence index is designed to address edge effects, snag and 

downed log reduction, and habitat loss and fragmentation resulting from road-associated factors. This index is calculated by using GIS with a current open roads data layer 

and late-successional habitat layer. Open roads are buffered by 50 m on both sides, 

and the area within this buffer is determined for the entire LSR, MLSA, or late-successional habitat in a 5th-field watershed. This number is then divided by the total amount 

of late-successional habitat in the LSR, MLSA, or in a 5th-field watershed to determine 

the proportion of late-successional habitats that could be influenced by open roads. 

Once the habitat influence index has been calculated, then the relative level of influence of road-associated factors on late-successional habitat can be determined. The 

scale used to determine the level of influence is as follows: <30 percent within habitat 

influence buffer is ranked as a low level of human influence on late-successional habitats, 30 to 50 percent is ranked as a moderate level of influence on late-successional 

habitats, and >50 percent is ranked as a high level of influence on late-successional 

habitats. 

Late-successional nonwinter security habitat—The second nonwinter index is 

a modification of the security habitat index described in the WNFLSRA (USDA FS 

1997). This index is used to evaluate the effects of displacement and avoidance, 

disturbance, and human access that can lead to trapping. This index is calculated by 

using GIS and current trail and open road data layers. Open roads and motorized trails 

are buffered by 200 m (Foppen and Reijnen 1994, Hamann et al. 1999, Hutto 1995), 

and nonmotorized trails are buffered by 100 m (Hamann et al. 1999, Miller et al. 1998). 

Assessment Processes 

for Focal Species
30

The area outside this buffer, referred to as security habitat, is determined for late-successional habitat in an LSR, MLSA, or in a 5th-field watershed. This number is then 

divided by the total area in late-successional habitat in an LSR, MLSA, or 5th-field watershed to determine the proportion that is in security habitat and may provide refugia 

for some late-successional-associated species. 

Once the amount of late-successional security habitat has been determined for the 

LSR, MLSA, or 5th-field watershed, then a relative rating of the level of influence of human activities on late-successional habitat can be made. This scale is as follows: <50 

percent security habitat is ranked as high level of human influence on the late-successional habitat, 50 to 70 percent security habitat is ranked as moderate level of human 

influence on late-successional habitat, and >70 percent security habitat is ranked as 

low level of human influence on late-successional habitat. 

Late-successional winter security habitat—To evaluate the effects of winter recreation trails, a winter security habitat index should be calculated. This index is calculated by using GIS and a current data layer attributed with plowed roads, ski trails, and 

snowmobile routes within the late-successional habitat in an LSR, MLSA or 5th-field 

watershed. Plowed roads, ski trails, and snowmobile routes are buffered by 200 m on 

each side, and the area outside of this buffer is referred to as winter security habitat. 

This number is then divided by the total area of late-successional habitat in the LSR, 

MLSA, or 5th-field watershed to determine the proportion of the late-successional habitat in the LSR, MLSA, or 5th-field watershed that is late-successional winter security 

habitat. 

Once the amount of late-successional winter security habitat has been determined for 

the LSR, MLSA, or 5th-field watershed, then a relative rating of the level of influence of 

human activities on late-successional habitat can be made. This scale is as follows: 

<50 percent winter security habitat is ranked as high level of human influence on latesuccessional habitat, 50 to 70 percent winter security habitat is ranked as moderate 

level of human influence on late-successional habitat, and >70 percent winter security 

habitat is ranked as low level of human influence on late-successional habitat 

There is currently a lack of information on the effects of recreational trails on many 

of the wildlife species associated with late-successional habitats. This makes it 

difficult to develop good management strategies or to assess the effects of projects 

on these species. Specifically, the influence of recreation trails on space-use patterns 

of late-successional species at different levels of recreation use and for different types 

of uses needs to be studied. Research that links the effects of recreational activities to 

the demography of late-successional species would be especially valuable. 

Until additional research becomes available, the assessment processes identified 

should be considered as working hypotheses on which monitoring could be designed 

to test their validity. For example, the influence that roads have on the availability of 

late-successional habitat structure adjacent to roads as a result of snag cutting and 

tree felling for firewood or traffic safety could be monitored to determine the validity of 

the habitat loss index. In addition, the concept of security habitat could be evaluated 

by monitoring the demography of focal late-successional species in areas identified as 

security habitat compared to those in areas that are not security habitat. 

Information Gaps and 

Research

Monitoring and Adaptive 

Management
31

Habitat effectiveness monitoring—The habitat influence index and the security 

habitat indices could be used to establish baseline levels of habitat effectiveness 

within LSR, MLSAs, and late-successional habitat in a 5th-field watershed. Periodic 

application of these models could show trends in habitat effectiveness over time. 

Population monitoring—Monitoring within LSRs and MLSAs could be used to track 

habitat effectiveness in relation to species abundance. For example, protocols have 

been developed to survey and locate goshawk nest sites and monitor their productivity 

(Watson et al. 1999). Brown creepers, pygmy nuthatches, white-breasted nuthatches, 

and white-headed woodpeckers can be monitored by using point counts (Ralph et 

al. 1993), or nest searches could be conducted to evaluate productivity (Ralph et al. 

1993). American marten and fisher populations can be indexed by using track plate 

surveys (Zielinski and Kucera 1995). These protocols could be used to monitor focal 

late-successional species populations within different late-successional habitats. 

Northern spotted owl population monitoring has been ongoing on the Wenatchee and 

Okanogan National Forests for the past 10 years (Forsman et al. 1996, Van Deusen 

et al. 1998). These monitoring efforts have indicated a stable to declining population 

but have not been able to reveal any causal factors at this time. An additional research 

proposal is being developed that may provide additional insights into causes of the 

population decline and address how some types of recreational activities may influence spotted owl habitat use and reproduction. 

There were 144 wildlife species in the riparian habitat species group (see app.). The 

focal species identified for this group includes the Cascades frog (Rana cascadae), 

tailed frog (Ascaphus truei), harlequin duck (Histrionicus histrionicus), bald eagle 

(Haliaeetus leucocephalus), water shrew (Sorex palustris), and black-capped chickadee (Parus atricapillus). These species were selected because they represent a diversity of riparian habitats and were sensitive to a variety of road- and trail-associated 

factors (table 12). 

Wildlife species associated with riparian habitats are particularly vulnerable to the effects of recreational activities on their habitats because of the concentration of these 

activities in riparian areas. Riparian habitats occur in a linear configuration within watersheds and are often traversed by roads and trails. In addition, riparian habitats are 

used by a variety of wildlife species and are used disproportionately more than they 

are available (Thomas et al. 1979). 

The road- and trail-associated factors for the Cascades frog and tailed frog were 

derived from studies of a variety of amphibian species and included collisions, habitat loss or fragmentation, and movement barriers and filters (table 12) (Ashley and 

Robinson 1996, DeMaynadier and Hunter 2000, Fahrig et al. 1995, Gibbs 1998, Rei 

and Seitz 1990, Welsh and Ollivier 1998, Wisdom et al. 2000, Yanes et al. 1995). 

Studies have shown that harlequin ducks are sensitive to human disturbances during the breeding season (Cassier and Groves 1989, Hamann et al. 1999, Wallen and 

Groves 1989). Ashley (1994) found that Harlequin ducks use stream habitats inaccessible to humans more than expected. Wallen (1987) reported that fishing along 

trails seems more disruptive than hiking. Harlequins avoided humans on 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 has 

a direct effect on harlequin ducks as birds have been found entangled in fishing line 

Riparian Habitat 

Assessment 

Introduction and Focal 

Species Selection

Summary of Recreation 

Route-Associated 

Factors for Focal 

Species
32

Focal 

species

Road-associated 

factors

Motorized trailassociated factorsNonmotorized trailassociated factorsSnowmobile routeassociated factors

Ski trailassociated 

factors

Cascades frog a Collisions

Habitat loss or 

 fragmentation

Movement barrier or

 filter

Collisions

Habitat loss or 

 fragmentation

Tailed frog b Collisions

Habitat loss or 

 fragmentation

Edge effects

Movement barrier or

 filter

Collisions

Habitat loss or 

 fragmentation

Harlequin 

 duck c

Downed log reduction

Disturbance at a 

 specific site

Displacement or 

 avoidance

Habitat loss or 

 fragmentation

Negative human 

 interactions

Disturbance at a 

 specific site

Displacement or 

 avoidance

Negative human 

 interactions

Disturbance at a 

 specific site

Displacement or 

 avoidance

Negative human 

 interactions

Bald eagle d Poaching

Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Disturbance 

 at a specific 

 site

Water shrew e Collisions

Movement barrier or

 filter

Habitat loss or 

 fragmentation

Downed log reduction

Collisions Snow compaction

Displacement or 

 avoidance

Snow 

 compaction

Black-capped 

 chickadee f

Displacement or 

 avoidance

Habitat loss or 

 fragmentation

Displacement or 

 avoidance

Habitat loss or 

 fragmentation

Displacement or 

 avoidance

Habitat loss or 

 fragmentation

Table 12—Road- and trail-associated factors for riparian associated focal species

a Sources: Ashley and Robinson 1996, DeMaynadier and Hunter 2000, Fahrig et al. 1995, Gibbs 1998, Rei and Seitz 1990, Welsh and Ollivier 

1998, Wisdom et al. 2000, Yanes et al. 1995.

b Sources: Ashley and Robinson 1996, DeMaynadier and Hunter 2000, Fahrig et al. 1995, Gibbs 1998, Rei and Seitz 1990, Welsh and Ollivier 

1998, Wisdom et al. 2000, Yanes et al. 1995.

c Sources: Ashley 1994, Clarkson 1992, Hamann et al. 1999, Wallen 1987, Wisdom et al. 2000.

d Sources: Fletcher et al. 1999, Hamann et al. 1999, Harmata and Oakleaf 1992, Skagen et al. 1991, Stalmaster and Newman 1978.

e Sources: Baldwin and Stoddard 1973, Cole and Landres 1995, Hickman 1990, Knight and Cole 1991, Randgaard 1998, Schmid 1972.

f Sources: Belisle et al. 2001, Blakesley and Reese 1988, Garton et al. 1977.
33

(Ashley 1994, Clarkson 1992). The road- and recreation-trail associated factors that 

were identified for the harlequin duck include snag reduction, disturbance at a specific 

site (nest site), displacement and avoidance, and habitat loss and fragmentation from 

roads (table 12) (Hamann et al. 1999, Wisdom et al. 2000). Cassier and Groves (1990) 

recommended that trails and roads be located at least 50 m from streams used by 

harlequin ducks. 

The response of bald eagles to human activities is variable. Reported responses have 

included spatial avoidance of activity and reproductive failure (Anthony et al. 1995, 

Buehler et al. 1991, Hamann et al. 1999, McGarigal et al. 1991, Watson 1993), although in some cases, eagles tolerate human disturbances (Harmata and Oakleaf 

1992). The road- and recreation-trail associated factors that were identified in this 

review included poaching, disturbance at a specific site, and avoidance and displacement (table 12) (Skagen et al. 1991, Stalmaster and Newman 1978). Bald eagles seem 

to be more sensitive to humans afoot than to vehicular traffic (Grubb and King 1991, 

Hamann et al. 1999, 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. Montopoli and 

Anderson (1991) developed a cumulative-effects model for bald eagles that included 

human disturbances associated with recreational boating. No model has been developed for assessing the cumulative effects of linear recreation routes on bald eagle 

habitats. Recommended buffer distances to reduce the potential for disturbance to 

eagles during the nesting period have ranged from 300 to 800 m (Anthony and Isaacs 

1989, Fraser et al. 1985, McGarigal 1988, Stalmaster 1987). Grubb and King (1991) 

evaluated the influence of pedestrian traffic and vehicle traffic on bald eagle nesting 

activities and recommended buffers of 550 m for pedestrians and 450 m for vehicles. 

The water shrew is known to be associated with riparian habitats and occurs at high 

enough densities to make it a good candidate for monitoring (Peffer 2001). The 

road- and recreation-trail associated factors for the water shrew include collisions, 

movement barriers and filters, habitat loss and fragmentation, downed log reduction, displacement and avoidance, and snow compaction (table 12), based on effects 

documented for other small mammal species as well (Baldwin and Stoddard 1973, 

Cole and Landres 1995, Knight and Cole 1991, Randgaard 1998, Schmid 1972). Snow 

compaction from snowmobiling and ski trail grooming has been cited to cause mortality and to present barriers to small mammal movements in subnivean spaces (Schmid 

1972). 

Some forest birds, such as American robins (Turdus migratorius), that are associated 

with riparian habitats are attracted to campgrounds that occur within riparian areas 

along roads and trails (Blakesley and Reese 1988, Marzluff 1997). Others, such as 

the black-capped chickadee, fox sparrow (Passerella iliaca) and song sparrow 

(Melospiza melodia) are negatively associated with campgrounds (Blakesley and 

Reese 1988, Garton et al. 1977, Marzluff 1997). In addition, Odell and Knight (2001) 

showed that black-capped chickadee densities increased with increasing distance 

from exurban housing developments. Belisle et al. (2001) found that the movement 

patterns of black-capped chickadees were influenced by forest cover removal. We 

included the black-capped chickadee as a focal species to address the displacement 

or avoidance factor that occurs when roads or trails provide access to campgrounds 

(table 12) and to address the removal of forest cover for roads and campgrounds. 
34

To evaluate the cumulative effects of roads and recreation trails on riparian-associated 

species, the evaluation area should be the 5th-field watershed in which the proposed 

project is located. Riparian reserves (RR) or riparian habitat conservation areas 

(RHCAs) are management allocations designed to provide a variety of functions for 

aquatic and terrestrial species (USDA FS 1994). For terrestrial species, these include 

providing habitat and connectivity between habitat patches (USDA FS 1994). The assessment processes to evaluate the effects of roads and recreational trails on riparian habitats should be divided into winter and nonwinter periods. We created five GIS 

models to evaluate the influences of winter recreation routes; three models provide 

a general index to the overall level of human influence on riparian habitats, and two 

models are species specific. Any or all of these models can be applied depending on 

the species being addressed and the issues identified for a project. 

Riparian nonwinter habitat influence index—For the nonwinter period, a habitat 

influence index should be calculated for all the RRs or the RHCAs within the watershed. The habitat influence index is designed to address edge effects, and snag and 

downed log reduction road-associated factors. This index is calculated by using GIS 

and a current open-roads data layer. Open roads are buffered by 60 m on both sides, 

and the area within this buffer is determined for the entire area that is within RRs or 

RHCAs in a watershed. The 60-m buffer is based on information presented in Hamann 

et al. (1999) on the degree of habitat affected by woodcutting along roads. The area 

within the buffer is then divided by the total area within RR or RHCA in the watershed 

to determine the proportion of the riparian habitat influenced by open roads. 

We calculated a relative rating to determine the extent that recreation activities influence riparian habitats. The relative rating is as follows: <30 percent of the RR or 

RHCA in an open road buffer is ranked as a low level of human influence on riparian 

habitats, 30 to 50 percent is ranked as a moderate level, and >50 percent is ranked as 

a high level of human influence on riparian habitats. 

Riparian habitat nonwinter route density index—In addition to the habitat influence 

index, the density of open roads within RRs or RHCAs should be calculated for the 

watershed by using a moving window analysis with a 0.9-km-radius circular window. 

This index is used to evaluate the potential for collisions, habitat loss and fragmentation, and edge-effect road-associated factors to influence wildlife habitats. A high level 

of human influence on riparian habitat = >25 percent of the riparian habitat within a 

watershed has route densities >3.2 km/0.9-km-radius circle (>2 mi/mi2), a moderate 

level of human influence = >25 percent of the riparian habitat within watershed with 

route densities >1.6 km/0.9-km-radius circle (>1 mi/mi2) and <3.2 km/0.9 km-radius 

circle (<2 mi/mi2), and a low level of human influence = <25 percent of the riparian 

habitat within a watershed with route densities >1.6 km/0.9-km-radius circle (>1 mi/

mi2). 

Riparian habitat winter recreation route density index—For the winter period, 

the density of plowed roads, groomed ski trails, and snowmobile routes within RRs 

or RHCAs in the watershed should be calculated by using a moving window analysis 

with a 0.9-km-radius circular window. This provides an index of the effects of winter 

recreation routes on riparian habitats. A high level of human influence on riparian 

habitat = >25 percent of the riparian habitat within a watershed that has route densities >3.2 km/0.9-km-radius circle (>2 mi/mi2), a moderate level of human influence = 

>25 percent of the riparian habitat within a watershed with route densities >1.6 km/

Assessment Processes 

for Focal Species
35

0.9-km-radius circle (>1 mi/mi2), and a low level of human influence = <25 percent of 

the riparian habitat within a watershed with route densities >1.6 km/0.9-km-radius 

circle (>1 mi/mi2). 

Bald eagle nesting habitat disturbance index—To evaluate the potential influences 

of human activities on bald eagle nesting habitat, the bald eagle nesting habitat disturbance index should be applied. This index should be applied to potential nesting habitat within a 5th-field watershed for activities that occur during the nesting period, which 

is February through August (Rodrick and Milner 1991). A 550-m zone of influence is 

applied to each side of nonmotorized trails and 450 m to motorized trails and roads. 

The zone of influence may be modified based on the topography adjacent to the linear 

recreation route. The proportion of potential nesting habitat within a zone of influence 

is then calculated and the following relative ranking is applied: <30 percent of the potential nesting habitat in a watershed in a zone of influence is ranked as a low level of 

human influence, 30 to 50 percent is ranked as a moderate level, and >50 percent is 

ranked as a high level of human influence on bald eagle nesting habitats. 

Harlequin duck nesting habitat disturbance index—This index can be used to 

evaluate the level of human influence on harlequin duck nesting habitats during their 

nesting period. The nesting period on the Okanogan and Wenatchee National Forests 

is from February through August. This index is based on the amount of potential nesting habitat within a 5th-field watershed. A 50-m zone of influence is then applied to 

each side of roads, motorized trails, and nonmotorized trails. The proportion of the 

potential nesting habitats that occurs within a zone of influence is then determined for 

each watershed. A relative ranking can then be applied to compare the relative levels 

of human influence among watersheds. The relative rankings are <30 percent of the 

potential nesting habitat in a watershed in a zone of influence is ranked as a low level 

of human influence, 30 to 50 percent is ranked as a moderate level, and >50 percent 

is ranked as a high level of human influence on harlequin duck nesting habitats. 

Research is needed to develop a thorough understanding of the influences of roadand trail-associated factors on riparian species, particularly research that links human uses to effects on animal population demographics. Specifically, research needs 

to be conducted to determine the extent to which roads and recreation trails serve 

as dispersal barriers or filters for amphibians and small mammals. A more complete 

understanding of the influences that road and recreation trails have on harlequin duck 

reproduction and survival is needed. For example, a better understanding of the relationship between the intensity of human use and its effects on harlequin duck reproduction would be helpful to design effective management strategies. 

Habitat monitoring—Application of the assessment models for riparian-associated 

species could be applied periodically to assess trends in the influence of roads and 

recreation trails on riparian habitats. Validation monitoring needs to be implemented 

to determine the validity of the assessment models and link them to population demographics of the focal riparian species. 

Population monitoring—Populations of Cascades frogs and small mammals (such 

as water shrews) could be monitored by using pitfalls traps (Jones et al. 1996) within 

riparian habitats that are influenced by road- and trail-associated factors, and compared to areas not influenced (to serve as controls). Specific locations where frogs disperse across roads should be monitored for road-specific mortality and to determine if 

Information Gaps and 

Research

Monitoring and Adaptive 

Management 
36

management changes are needed. Populations of harlequin ducks could be surveyed 

following the Forest Service survey protocol and a comparison made between areas 

with roads and recreation trails compared to those without. A few bald eagle nest sites 

have been located on the Okanogan and Wenatchee National Forests, and they are 

being monitored as part of forest plan monitoring. Monitoring of black-capped chickadees in campground and noncampground sites could be accomplished by using point 

counts (Ralph et al. 1993) and following the methods of Blakesley and Reese (1988). 

A total of 97 wildlife species is in this group (see app.). Focal species that were selected included the common loon (Gavia immer), great blue heron (Ardea herodias), 

eared grebe (Podiceps nigricolis), and wood duck (Aix sponsa). Loons use large rivers 

and lakes as nesting habitat and are listed as a “sensitive” species. The eared grebe 

uses ponds and lakes up to the ponderosa pine zone and also is listed as a “sensitive” 

species. Great blue herons use lowland rivers, and wood ducks nest in cavities adjacent to small ponds and lakes. Together, these species represent a variety of habitats, 

and road- and trail-associated factors (table 13). 

Human disturbance is known to negatively affect waterfowl and colonial waterbirds 

(Anderson 1988; Belanger and Bedard 1989, 1990; Boellstorff et al. 1988; Gotmark 

and Ahlund 1984; Havera et al. 1992; Henson and Grant 1991; Madsen 1985; Owens 

1977; Pierce and Simons 1986; Tremblay and Ellison 1979). These studies have 

shown that human disturbances associated with recreational activities can affect productivity in many ways including nest abandonment, egg mortality owing to exposure, 

increased predation of eggs and hatchlings, depressed feeding rates on wintering and 

staging grounds, and avoidance of otherwise suitable habitat. 

The common loon, great blue heron, eared grebe, and wood duck were selected as 

focal species and can be influenced by several forms of human activities (Hamann et 

al. 1999, Klein 1993, Titus and VanDruff 1981). The road and recreation trail factors 

associated with these species included disturbance during nesting, and displacement 

from habitat (table 13) (Ashley 1994, Hamann et al. 1999, Kelly 1992, Klein 1993, 

Markham and Brechtel 1979, McEneaney 1994, Rodgers and Smith 1995, Titus and 

VanDruff 1981, Vos et al. 1985, Wallen 1987, Werschkul et al. 1976). No ski- or snowmobile route-associated factors were identified for these species as winter recreation 

generally occurs outside of the nesting and rearing periods when they are the most 

susceptible. 

Titus and VanDruff (1981) reported that population characteristics, nest and egg 

production, nest and egg losses, flushing distances, and hatching and brood rearing success for common loons was influenced by human activities such as hiking and 

boating, but there were no significant differences between areas of high and low human use. Vermeer (1973) showed an inverse relationship between numbers of breeding pairs of loons and the level of human disturbance. Ream (1976) reported that 

campers and canoeists displaced loons from their nests. 

Klein (1993) reported that great blue heron responses to humans in vehicles and afoot 

varied from no response to flying away, and that they reacted more to humans on foot 

than in vehicles. Rodgers and Smith (1995) reported that great blue herons flushed at 

a mean distance of 32.0 ± 12.3 m in response to persons approaching on foot. They 

recommended a 100-m setback to limit disturbance to nesting colonies. Skagen et 

al. (2001) found a reduction in the number of great blue heron nests when they were 

Waterfowl and 

Colonial Nesting 

Bird Habitat 

Assessment 

Introduction and Focal 

Species Selection

Summary of Recreation 

Route-Associated 

Factors for Focal 

Species
37

Table 13—Road- and recreation trail-associated factors for waterfowl and colonial nesting focal species

a Sources: Hamann et al. 1999, Ream 1976, Titus and VanDruff 1981, Vermeer 1973. 

b Sources: Klein 1993, Rodgers and Smith 1995, Skagen et al. 2001.

c Source: Hamann et al. 1999.

d Source: Hamann et al. 1999.

Focal 

species

Road-associated 

factors

Motorized trailassociated factorsNonmotorized trailassociated factorsSnowmobile routeassociated factors

Ski trailassociated 

factors

Common loona Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Displacement or 

 avoidance

Great blue 

 heronb

Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Displacement

 or avoidance

Disturbance at a 

 specific site

Displacement or 

 avoidance

Route for competitors

Eared grebec Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Displacement or 

 avoidance

Wood duckd Snag reduction

Disturbance at a 

 specific site

Displacement or 

 avoidance

Disturbance at a 

 specific site

Displacement or 

 avoidance

Snag reduction

Disturbance at a 

 specific site

Displacement or 

 avoidance

Snag reduction

exposed to humans on foot. In addition, she reported an increase in competition between great blue herons and cormorants, as cormorants were more tolerant of human 

activities. 

Wood ducks nest in cavities and can be affected by the loss of snag habitat associated with firewood gathering and felling of snags for safety when roads are near nesting 

habitat (Hamann et al. 1999). 

Waterfowl and colonial nester habitat disturbance index—To evaluate the cumulative effects of roads and recreation trails on nesting and habitat use, the assessment 

model described below would be applied at the 5th-field watershed scale. Potential 

nesting habitats such as lakes, rivers, and ponds should be identified within a watershed and put into GIS. A 250-m habitat zone is then placed around each of the 

identified habitats, and the area within this zone is summed for the watershed. These 

habitats are overlaid with roads, motorized trails, and nonmotorized trails. Roads and 

recreation trails are then buffered by a 250-m zone of influence on each side. The 

proportion of the habitat zone that lies outside of a zone of influence of a road or trail 

is then determined. The 250-m zone of influence is based on distances at which birds 

have been observed to be affected by human disturbances (Hamann et al. 1999, 

Kelly 1992, Markham and Brechtel 1978, Rodgers and Smith 1995, Vos et al. 1985). 

Assessment Processes 

for Focal Species
38

Outputs of this model include the proportion of potential habitat in a watershed affected by road-associated factors, motorized trails and nonmotorized trails, and the overall 

influence of roads and trails. 

Hamann et al. (1999) reported that when over half of the available habitat around a 

lake was disturbed by human activities, loons did not nest. This estimate was used 

to establish a preliminary cumulative effects threshold and to rank the level of human 

influence on these habitats within a watershed. The relative ranking is as follows: <50 

percent of the potential habitat outside of the zone of influence of a road or trail is 

ranked as high level of human influence, 50 to 70 percent of the potential habitat in a 

zone of influence is ranked as moderate level of human influence, and >70 percent is 

ranked as a low level of human influence. 

Additional research is needed to relate road- and trail-associated factors to demographic responses of the focal species. In addition, research that explores how different types and intensities of road and trail uses affect focal waterfowl and colonial 

nester species would allow for the refinement of the cumulative effects models. 

Habitat-effectiveness monitoring—The cumulative effects model described for 

these focal species could be used to establish baseline conditions for their habitats 

within watersheds. These models could then be periodically applied to monitor trends 

in human influences on habitat over time. 

Population monitoring—The numbers and productivity of the focal species in this 

group could be monitored by selecting representative lakes, ponds, and rivers that 

have different levels of human activities adjacent to them. In this manner, population 

trends could be monitored, and these trends could be correlated to different levels of 

human activity. 

A total of 11 species was included in the primary cavity excavator (PCE) group (see 

app.). The species selected as focal species included the white-headed woodpecker, 

three-toed woodpecker (Picoides tridactylus), and pileated woodpecker (Dryocopus 

pileatus) (table 14). The white-headed woodpecker was selected because of its association with old ponderosa pine forests, three-toed woodpeckers with subalpine fir 

forests, and pileated with mixed-conifer forests. 

Only road-associated factors were identified for these species as the available literature did not suggest that recreation trail-associated disturbances presented a problem 

for primary cavity excavators (Hamann et al. 1999). Recreational activity is unlikely to 

be focused around the nest sites of these species and, by design, woodpeckers and 

other cavity users are relatively more secure from nest predation than any other group 

of forest birds (Hamann et al. 1999). Therefore, at present, recreational disturbance is 

not known to be a major limiting factor. 

The road-associated factors included the negative edge effects of roads on PCE habitat and snag and down log reduction resulting from wood cutting and safety practices 

along roads (table 14) (Bull and Holthausen 1993, Hitchcox 1996, Hutto 1995, Milne 

and Hejl 1989, Raphael and White 1976). The distances in which woodcutters can 

harvest snags from roads differ according to terrain. Distances reported by Hamann et 

al. (1999) ranged from 65 to 200 m. 

Information Gaps and 

Research Needs

Primary Cavity 

Excavator Habitat 

Assessment 

Introduction and Focal 

Species Selection

Monitoring and Adaptive 

Management 

Summary of Recreation 

Route-Associated 

Factors for Focal 

Species
39

Table 14—Road- and trail-associated factors for primary cavity excavator focal species

a Sources: Bull and Holthausen 1993, Hamann et al. 1999, Hitchcox 1996, Hutto 1995, Milne and Hejl 1989, Raphael and White 1976.

Focal species

Road-associated 

factors

Motorized trailassociated factorsNonmotorized trailassociated factorsSnowmobile routeassociated factors

Ski trailassociated 

factors

White-headed 

 woodpecker a

Snag reduction

Edge effects

Three-toed 

 woodpeckera

Snag reduction

Edge effects

Pileated 

 woodpeckera

Snag reduction

Down log reduction

Edge effects

Primary cavity excavator habitat influence index—The assessment processes to 

evaluate the cumulative effects of road-associated factors on primary cavity excavators would be applied to the 5th-field watershed. Open roads that occur within forested 

habitats (>10 percent tree cover) are buffered by 60 m on each side to determine the 

potential influence on cavity excavator habitat. The amount of forested habitat within 

this buffer is then determined and divided by the total amount of forested habitat within 

the watershed. In this manner, an index to the proportion of primary cavity excavator 

habitat influenced by roads within a watershed is derived. A relative ranking is then determined based on the following scale: <30 percent of forested habitat in an open road 

buffer is ranked as a low level of human influence on primary cavity excavator habitat, 

30 to 50 percent is ranked as a moderate level of influence, and >50 percent is ranked 

as a high level of influence. 

Research is needed to link road-associated factors to the demography of the focal 

species for this wildlife group. Additional research is needed to validate the assumption that recreation trails are not a limiting factor for primary cavity excavator populations. 

Habitat monitoring—The habitat influence index for primary cavity excavators could 

be applied periodically to determine baseline conditions and track the changes to habitat over time. Monitoring needs to be completed to validate the zone of influence along 

roads in primary cavity excavator habitat. This could be done by sampling habitat 

structure at varying distances from roads in a variety of forested habitat types. 

Population monitoring—Populations of primary cavity excavators could be monitored by using point counts (Bull et al. 1990, Huff et al. 2001) established in a variety 

of habitats and in areas with and without road- and recreation trail-associated factors. 

Information Gaps and 

Research

Assessment Processes 

for Focal Species

Monitoring and Adaptive 

Management 
40

This section illustrates how cumulative effects of linear recreation routes on wildlife 

habitats can be assessed by using the GIS models developed in the previous sections. This section is intended to display current conditions relative to the influences 

that linear recreation routes have on various wildlife habitats, which in turn provides a 

baseline of information for planning efforts. Finally, this section discusses the results 

and management implications of applying the proposed cumulative effects models. 

The assessment area includes all of the lands that lie to the east of the crest of the 

North Cascade Range between Lake Chelan and the Interstate 90 Highway corridor, 

extending east to the Columbia River. This area provides a diversity of winter and nonwinter recreation opportunities and a diversity of wildlife habitats making it an excellent area to “test drive” the proposed cumulative effects process. The area includes 11 

BMUs, 22 LAUs, 9 ungulate winter range units, 15 LSRs (including MLSAs), and 19 

5th-field watersheds. 

We applied 15 of the 18 GIS cumulative effects assessment models to evaluate wildlife 

habitats within the case study area (table 15). Four of the models were used to evaluate winter recreational activities on wildlife habitats; 10 models were for the nonwinter 

periods, and one model, the wolverine denning model, included winter and spring periods. The three models that were not applied included the deer and elk summer habitat 

effectiveness model, bald eagle nesting habitat disturbance model, and Harlequin 

duck nesting habitat disturbance model. These models were not run at this time because of either limited computing power or a lack of information about the habitat of a 

focal species. 

Wide-ranging carnivore habitats—During the early season, 36 percent of the BMUs 

were rated as a high level of human influence, 27 percent as moderate, and 36 percent as low (table 16). During the mid and late seasons, trails became snow free and 

received enough use to be classified as high-use trails resulting in a higher proportion 

of BMUs with a high level of human influence. Sixty-four percent of the BMUs were 

ranked as high level of human influence, 18 percent as moderate, and 18 percent as 

low during the mid and late seasons (table 16). 

This analysis suggests that cumulative effects are more of an issue for grizzly bear 

habitats during the mid and late seasons within the assessment area. Cumulative effects could be reduced through access management, and these opportunities could 

be identified during roads analysis (USDA FS 2000c). Seasonally important habitats to 

be considered for inclusion in core areas have been identified for each of these BMUs 

in the North Cascades ecosystem grizzly bear habitat assessment (NCETT 2001). 

During the nonwinter period, 36 percent of the analysis areas for gray wolf and wolverine habitats were ranked as having a high level of human influence, 36 percent as 

moderate, and 27 percent as low (table 17). Cumulative effects were more of an issue 

during the nonwinter season based on this analysis. Habitat effectiveness could be 

restored through road access management, and opportunities could be identified during roads analysis (USDA FS 2000c). During winter, all the assessment areas were 

ranked as having a low level of human influence from groomed and designated winter 

recreation routes (table 18). This assessment did not include winter routes that are 

not groomed or officially designated, such as snowmobile routes or snow-play areas. 

These have the potential to result in additional cumulative effects. 

Application of the 

Recreation Route 

Cumulative Effects 

Models: A Case 

Study 

Assessment Area

Assessment Models 

Applied

Results and Discussion
41

Table 15—Species groups, focal species, cumulative effects indices, and assessment areas used in the 

cumulative effects of roads and recreation trails on wildlife habitats case study

Species group Focal species Index Analysis unit

Wide-ranging carnivores Grizzly bear Grizzly bear assessment 

 model

Bear management unit

Wide-ranging carnivores Gray wolf and wolverine Gray wolf and wolverine 

 assessment model

Bear management unit

Wide-ranging carnivores Wolverine Potential denning habitat 

 model

Potential denning 

 habitat within bear 

 management units

Wide-ranging carnivores Lynx Lynx assessment model Lynx analysis unit

Ungulates Deer and elk Winter habitat disturbance 

 index

Winter range unit

Ungulates Bighorn sheep Summer or winter habitat 

 disturbance index

Summer or winter 

 range unit

Ungulates Deer and elk Summer habitat 

 disturbance index

Fifth-field watersheds

Ungulates Mountain goat Winter habitat 

 disturbance index

Fifth-field watersheds

Late successional Northern spotted owl, goshawk, brown 

 creeper, American marten, fisher, flying

 squirrel, pygmy nuthatch, white-breasted 

 nuthatch, white-headed woodpecker

Nonwinter habitat 

 influence index

Late-successional 

 habitat in reserves or 

 fifthfield watersheds

Late successional Northern spotted owl, goshawk, brown 

 creeper, American marten, fisher, flying 

 squirrel, pygmy nuthatch, white-breasted 

 nuthatch, white-headed woodpecker

Nonwinter security habitat Late-successional 

 habitat in reserves or 

 fifth-field watersheds

Late successional Northern spotted owl, goshawk, brown 

 creeper, American marten, fisher, flying 

 squirrel, pygmy nuthatch, white-breasted 

 nuthatch, white-headed woodpecker

Winter security habitat Late-successional 

 habitat in reserves or 

 fifth-field watersheds

Riparian Cascades frog, tailed frog, harlequin duck, 

 bald eagle, water shrew

Nonwinter habitat 

 influence index

Riparian reserves 

 within fifth-field 

 watersheds

Riparian Cascades frog, tailed frog, harlequin duck, 

 bald eagle, water shrew

Nonwinter road density 

 index

Riparian reserves 

 within fifth-field 

 watersheds

Riparian Cascades frog, tailed frog, harlequin duck, 

 bald eagle, water shrew

Winter recreation route 

 density index

Riparian reserves 

 within fifth-field 

 watersheds

Riparian Bald eagle Nesting habitat 

 disturbance index

Nesting habitat within 

 fifth-field watersheds

Riparian Harlequin duck Nesting habitat 

 disturbance index

Nesting habitat within 

 fifth-field watersheds

Waterfowl and colonial 

 nesters

Common loon, great blue heron, eared 

 grebe, wood duck

Habitat disturbance index Habitats within fifth-

 field watersheds

Primary cavity excavators White-headed woodpecker Habitat influence index Forested habitats within 

 fifth-field watersheds
42

The assessment of cumulative effects of groomed and designated winter recreation 

routes on lynx habitats showed that 4 percent of the LAUs had a high level of human 

influence, 20 percent had a moderate level, and 76 percent had a low level (table 19). 

Based on this analysis, cumulative effects are a significant issue within the Cascade 

crest LAU in the assessment area. This assessment did not include winter routes 

that are not groomed or officially designated, such as snowmobile routes or snow 

play areas. These have the potential to result in additional cumulative effects. 

Table 16—Cumulative effects of roads and trails on grizzly bear habitat within 

bear management units (BMUs) in the case study area

Early Relative Mid and late Relative

BMU season core ranking a season core ranking a

Percent Percent

Upper Chelan 87 Low 82 Low

Lower Chelan 62 Moderate 53 High

Upper Entiat 40 High 47 High

Lower Entiat 19 High 18 High

Chiwawa 60 Moderate 55 Moderate

Upper Wenatchee 73 Low 61 Moderate

Lower Wenatchee 38 High 39 High

Icicle 82 Low 73 Low

Peshastin 35 High 36 High

Swauk 63 Moderate 20 High

Cle Elum 81 Low 33 High

aHigh level of human influence = <55 percent core area per BMU, moderate level of human influence = 

55 to 70 percent core area per BMU, and low level of human influence = >70 percent core area per BMU.

Table 17—Cumulative effects of roads and motorized trails on gray wolf and 

wolverine habitat within bear management units (BMUs) in the case study area

Areas with Areas with 

road densities road densities 

Areas with >0 and <1.6 km/ >1.6 km/0.9-km- Relative

BMU no roads 0.9-km-radius circle radius circle rankinga

 - - - - - - - - - - - - - - Percent - - - - - - - - - - - - - - -

Upper Chelan 100 0 0 Low

Lower Chelan 57.3 9.9 32.8 Moderate

Upper Entiat 50.2 8.6 41.2 Moderate

Lower Entiat 6.7 9.1 84.2 High

Chiwawa 58.2 5.2 36.6 Moderate

Upper Wenatchee 67.1 6.8 26.1 Low

Lower Wenatchee 31.1 9.5 59.4 High

Icicle 84.3 4.0 11.7 Low

Peshastin 28.6 10.0 61.3 High

Swauk 13.9 8.7 77.3 High

Cle Elum 46.5 7.9 45.6 Moderate

aHigh level of human influence = <50 percent of a BMU with an open road/trail density of 3.2 km/0.9-km 

radius circle (<1 mi/mi2), moderate level of human influence = 50 to 70 percent of a BMU with an open 

road/trail density of between 1.6 and <3.2 km/0.9-km radius circle (<1 mi/mi2 and <2), and low level of 

human influence = >70 percent of a BMU with an open road/trail density of >1.6 km/0.9-km radius circle 

(<1 mi/mi2).
43

Table 18—Cumulative effects of groomed and designated winter recreation routes on potential 

wolverine denning habitat within bear analysis units (BMUs) in the case study area

Proportion of denning Proportion of denning

Denning habitat with road densities habitat with road densities Relative

BMU habitat >1.6 km/0.9-km-radius circle >3.2 km/0.9-km-radius circle rankinga

Hectares - - - - - - - - - - - - Percent - - - - - - - - - - - 

Upper Chelan 283 0 0 Low

Lower Chelan 1124 0 0 Low

Upper Entiat 1761 0 0 Low

Lower Entiat 162 0 0 Low

Chiwawa 332 0 0 Low

Upper Wenatchee 1014 0 0 Low

Lower Wenatchee 1500 0.1 0 Low

Icicle 3119 0 0 Low

Peshastin 143 0 0 Low

Swauk 793 0 0 Low

Cle Elum 793 0 0 Low

aHigh level of human influence = >25 percent of the BMU with route densities 3.2 km/0.9-km radius circle (>2 mi/mi2), moderate level of 

human influence = >25 percent of the BMU with route densities between 1.6 and <3.2 km/0.9-km radius circle (>1 mi/mi2 and >2), and low 

level of human influence = <25 percent of the BMU with route densities >1.6 km/0.9-km radius circle (>1 mi/mi2).

Table 19—Cumulative effects of groomed winter recreation routes within lynx analysis units (LAUs) in the 

case study area

Proportion of the Proportion of the Proportion of the 

LAU with groomed LAU with groomed LAU with groomed

route densities <1.6 km/ route densities 1.6 to 3.2 km/ route densities >3.2 km/ Relative

LAU 0.9-km-radius circle 0.9-km-radius circle 0.9-km-radius circle rankinga

Cascade Crest 19.5 23 57.5 High

Cooper Mountain 100 0 0 Low

Ferry Basin 100 0 0 Low

Hungry Ridge 100 0 0 Low

Indian Head Basin 100 0 0 Low

Copper Peak 100 0 0 Low

Upper Entiat 100 0 0 Low

Pyramid 99.9 .1 0 Low

Lake Basin 82.9 13.9 3.2 Low

Chiwawa 93.2 6.8 0 Low

Garland 92.7 7.2 .1 Low

Cougar 86.6 8.7 4.7 Low

Chumstick Mountain 70.7 10.8 18.5 Moderate

White River 99.4 .4 .2 Low

Little Wenatchee 100 0 0 Low

Nason 85.1 8.3 6.6 Low

Icicle Ridge 99.9 .1 0 Low

Upper Icicle 98.6 1.0 0.4 Low

Enchantment 99.8 .2 0 Low

Table Mountain 72.2 14 13.8 Moderate

Teanaway 83.6 11.1 5.3 Low

Waptus 92.6 6.2 1.2 Low

Sasse Ridge 73.1 10.8 16.1 Moderate

Silver 77.1 14 8.9 Moderate

Keechelus Ridge 63.9 13.1 23 Moderate

a High level of human influence = >25 percent of the LAU with route densities 3.2 km/0.9 km (>2 mi/mi2), moderate level of human influence = 

>25 percent of the LAU with route densities between 1.6 and <3.2 km/0.9-km radius circle (>1 mi/mi2), and low level of human influence = <25 

percent of the LAU with route densities >1.6 km/0.9 km-radius circle (>1 mi/mi2).
44

Table 20—Cumulative effects of groomed and designated winter 

recreation routes on deer and elk winter ranges within watersheds in 

the case study area

Hectares of Percentage outside of Relative

Watershed winter range a zone of influence rankinga

Chelan 3584 92.4 Low

Entiat 5893 95.9 Low

Columbia River-Antoine 2466 63.6 Moderate

Wenatchee 9358 92.9 Low

Columbia River-Navarre 2142 87.9 Low

Columbia River-Swakane 5360 98.7 Low

Mission 5216 87.7 Low

Columbia River-Stemilt 1158 97.8 Low

Swauk-Naneum 2134 95.4 Low

a Low = >70 percent outside a zone of influence, moderate = 50 to 70 percent outside a zone 

of influence, and high = <50 percent outside a zone of influence.

Ungulate winter habitats and bighorn sheep nonwinter habitats—During winter, 

groomed and designated winter recreation routes had lower levels of cumulative effects. None of the winter ranges had a high level of human influence on deer and elk, 

10 percent had a moderate level, and 90 percent had a low level (table 20). This same 

trend occurred for bighorn sheep. Assessment units for nonwinter bighorn sheep habitats showed one with a high level and one with a moderate level of human influence 

(table 21), whereas during winter, both ranked as low levels (table 22). 

Table 21—Cumulative effects of nonwinter 

recreation routes on bighorn sheep summer 

ranges in the case study area

Bighorn sheep Percentage outside Relative

summer range zone of influence rankinga

Lake Chelan 55.4 Moderate

Swakane 33.8 High

a Low = >70 percent outside a zone of influence, moderate = 

50 to 70 percent outside a zone of influence, and high = <50 

percent outside a zone of influence.

Table 22—Cumulative effects of groomed and designated 

winter recreation routes on bighorn sheep winter ranges in the 

case study area

Bighorn sheep Percentage outside Relative

winter range Hectares zone of influence rankinga

Lake Chelan 15 461 93.7 Low

Swakane 3 352 95.0 Low

a Low = >70 percent outside a zone of influence, moderate = 50 to 70 percent 

outside a zone of influence, and high = <50 percent outside a zone of influence.
45

The cumulative effects of nonwinter recreation routes on deer and elk habitat could 

be reduced through management of roads. Opportunities to enhance deer and elk 

habitat effectiveness through road management could be addressed during roads 

analysis (USDA FS 2000c). Only groomed and designated routes were considered in 

this assessment. Other routes may occur and could contribute to additional cumulative 

effects. 

Late-successional forest habitats—The results of applying the cumulative effects 

models to late-successional habitats within LSRs and MLSAs showed that nonwinter recreation routes currently ranked as a low level of direct habitat loss (table 23). 

However, nonwinter recreation routes had a high level of human influence on habitat 

effectiveness within 31 percent of the LSRs and MLSAs, a moderate level in 56 percent, and a low level in 13 percent (table 24). Habitat effectiveness could be improved 

through human access management, and opportunities could be identified during 

roads analysis (USDA FS 2000c) and project-level analyses. Groomed and designated winter recreation routes had a low level of human influence on winter habitat 

effectiveness of late-successional habitats (table 25). Other winter routes that are not 

groomed or designated were not considered in this assessment and may result in additional cumulative effects. 

Riparian habitats—The analysis of cumulative effects of nonwinter recreation routes 

on riparian habitat effectiveness showed that 95 percent of the assessment units had 

a high level of human influence, and 5 percent had a low level (table 26). This analysis 

showed that roads have the greatest cumulative effect on riparian habitat effectiveness. Opportunities to restore habitat effectiveness for riparian habitats could be identified during roads analysis (USDA FS 2000c). 

The riparian habitat influence index estimates the cumulative effects that roads have 

on habitat loss within riparian habitats. This assessment showed that 26 percent had 

a moderate level, and 74 percent had a low level (table 27). Opportunities to restore 

riparian habitats through road management could be identified through roads analysis 

(USDA FS 2000c). 

The winter route density index provides an estimate of the cumulative effects of winter 

recreation routes on riparian habitat effectiveness. This assessment showed that 5 

percent of the assessment areas ranked as a high level of human influence, 26 percent as a moderate level, and 68 percent as a low level (table 28). 

The assessments of riparian habitats showed that cumulative effects of linear recreation routes had the greatest impact from nonwinter recreation routes, reducing habitat 

effectiveness. Habitat effectiveness of riparian habitats could be restored through 

route access management and restoration opportunities identified through roads analysis (USDA FS 2000c). Riparian areas provide habitat for a large number of wildlife 

species (Thomas et al. 1979) and therefore should receive high priority for restoration. 

Waterfowl and colonial nesting bird habitats—The cumulative effects analysis for 

waterfowl and colonial nesting bird habitats showed that 68 percent of the assessment 

areas had a high level of human influence, 21 percent had a moderate level, and 10 

percent had a low level (table 29). Based on this assessment, cumulative effects on 

these habitats are relatively high. These areas provide habitat for a large number of 
46

Table 23—Habitat influence index for late-successional 

forest habitats within late-successional reserves (LSRs) 

and managed late-successional areas (MLSAs) in the 

case study area

Percentage inside Relative

LSR/MLSA zone of influence rankinga

Slide Peak 10.1 Low

Icicle 17.7 Low

Boundary Butte 24.5 Low

Sawtooth 0 Low

Shady Pass 10.8 Low

Chiwawa 14.0 Low

Lake Wenatchee 14.2 Low

Deadhorse 15.3 Low

Teanaway 6.4 Low

Swauk 23.9 Low

Eagle 22.8 Low

Twin Lake 3.6 Low

Tumwater 16.3 Low

Camas 22.0 Low

Sand Creek 12.4 Low

Natapoc 24.7 Low

a Low = <30 percent of the habitat in a zone of influence, moderate = 30 to 

50 percent, and high = >50 percent.

Table 24—Cumulative effects of nonwinter recreation 

routes on late-successional forest habitat effectiveness 

for late-successional reserves (LSRs) and managed 

late-successional areas (MLSAs) in the case study area

Percentage outside Relative

LSR/MLSA zone of influence rankinga

Slide Peak 41.7 High

Icicle 56.5 Moderate

Boundary Butte 46.1 High

Sawtooth 59.9 Moderate

Shady Pass 63.6 Moderate

Chiwawa 56.3 Moderate

Lake Wenatchee 63.9 Moderate

Deadhorse 58.9 Moderate

Teanaway 56.3 Moderate

Swauk 38.1 High

Eagle 42.7 High

Twin Lake 82.8 Low

Tumwater 58.6 Moderate

Camas 42.7 High

Sand Creek 54.4 Moderate

Natapoc 49.2 Low

a Low = <30 percent of the habitat in a zone of influence, moderate = 30 to 

50 percent, and high = >50 percent.
47

Table 25—Cumulative effects of groomed and designated 

winter recreation routes on late-successional forest 

habitat effectiveness for late-successional reserves 

(LSRs) and managed late-successional areas (MLSAs) 

in the case study area

 Percentage outside Relative

LSR/MLSA zone of influence rankinga

Slide Peak 66.7 Low

Icicle 100.0 Low

Boundary Butte 99.0 Low

Sawtooth 100.0 Low

Shady Pass 98.3 Low

Chiwawa 84.2 Low

Lake Wenatchee 94.8 Low

Deadhorse 93.2 Low

Teanaway 96.0 Low

Swauk 84.8 Low

Eagle 10.0 Low

Twin Lake 100.0 Low

Tumwater 86.2 Low

Camas 100.0 Low

Sand Creek 100.0 Low

Natapoc 93.9 Low

a Low = <30 percent of the habitat in a zone of influence, moderate = 30 to 

50 percent, and high = >50 percent.

Table 26—Nonwinter recreation route density index for riparian habitats in the case study area

Percentage with Percentage with Percentage with

recreation route recreation route recreation route

densities <1.6 km/ densities 1.6 to 3.2 km/ densities >3.2 km/ Relative

Watershed 0.9-km-radius circle 0.9-km-radius circle 0.9-km-radius circle rankinga

Chelan 48.3 22.7 29.0 High

Chiwawa 24.6 26.2 49.2 High

Entiat 17.5 23.7 58.7 High

White-Little Wenatchee 39.8 19.5 40.7 High

Columbia River-Antoine 0 70.7 29.3 High

Mad 7.2 15.6 77.1 High

Columbia River-Navarre 40.2 9.4 50.4 High

Wenatchee 18.6 21.5 60.0 High

Nason 17.4 21.0 61.7 High

Columbia River-Entiat 84.3 8.9 6.8 Low

Icicle 30.4 30.0 39.5 High

Columbia River-Swakane 38.0 33.2 28.8 High

Cle Elum 25.0 20.9 54.2 High

Peshastin 11.1 18.1 70.9 High

Mission 33.9 19.5 46.5 High

Yakima 14.7 24.2 61.1 High

Columbia River-Stemilt 22.9 7.8 69.3 High

Peshastin 16.9 31.6 51.5 High

Swauk-Nanuem 6.8 5.2 88.0 High

aHigh level of human influence = >25 percent of the watershed with 3.2 km/0.9-km radius circle (>2 mi/mi2), moderate level of 

human influence = >25 percent of the watershed with between 1.6 and <3.2 km/0.9-km radius circle (>1 mi/mi2 and >2), and low 

level of human influence = <25 percent of the watershed with 1.6 km/0.9-km radius circle (>1 mi/mi2).
48

Table 27—Nonwinter riparian habitat influence index for watersheds located in the 

case study area

Hectares of Percentage of riparian habitats Relative

Watershed riparian habitat in a zone of influence rankinga

Chelan 19 972 5.6 Low

Chiwawa 8 240 13.0 Low

Entiat 11 830 21.9 Low

White-Little Wenatchee 11 428 9.9 Low

Columbia River-Antoine 4 0 Low

Mad 3 803 22.7 Low

Columbia River-Navarre 753 35.3 Moderate

Wenatchee 11 361 33.9 Moderate

Nason 3 932 20.9 Low

Columbia River-Entiat 426 .9 Low

Icicle 8 493 6.7 Low

Columbia River-Swakane 1 261 23.6 Low

Cle Elum 11 328 11.0 Low

Peshastin 4 757 31.8 Moderate

Mission 2 768 20.1 Low

Yakima 7 228 14.9 Low

Columbia River-Stemilt 453 33.5 Moderate

Peshastin 4 829 14.6 Low

Swauk-Naneum 5 087 39.3 Moderate

a Low level of human influence = <30 percent of the habitat in the watershed within a zone of influence, 

moderate level of human influence = 30 to 50 percent of the habitat in the watershed within a zone of influence, 

and high level of human influence = >50 percent of the habitat in the watershed within a zone of influence.

Table 28—Winter recreation route density index for riparian habitats in the case study area

Percentage with Percentage with Percentage with

recreation route recreation route recreation route

densities <1.6 km/ densities 1.6 to 3.2 km/ densities >3.2 km/ Relative

Watershed 0.9-km-radius circle 0.9-km-radius circle 0.9-km-radius circle rankinga

Chelan 92.9 6.3 1 Low

Chiwawa 69.6 20 11 Moderate

Entiat 87 12 1 Low

White-Little Wenatchee 91.2 4 4 Low

Columbia River-Antoine 100 0 0 Low

Mad 77.8 8.8 13.4 Low

Columbia River-Navarre 87.4 12.6 0 Low

Wenatchee 75.5 17.3 7.3 Moderate

Nason 63.8 20.2 16 Moderate

Columbia River-Entiat 59.4 40.6 0 Low

Icicle 98.7 1.3 0 Low

Columbia River-Swakane 95.8 4.2 0 Low

Cle Elum 73 13 14 Moderate

Peshastin 83.1 16.8 1 Low

Mission 98.2 1.8 0 Low

Yakima 54.8 20.5 25 High

Columbia River-Stemilt 83 7.8 9 Low

Peshastin 86.3 9.3 5 Low

Swauk-Naneum 52.2 23.2 25 High

a High level of human influence = >25 percent of the watershed with 3.2 km/0.9-km radius circle (<1 mi/mi2), moderate level of 

human influence = >25 percent of the watershed with between 1.6 and <3.2 km/0.9-km radius circle (<1 mi/mi2 and <2) and low 

level of human influence = <25 percent of the watershed with >1.6 km/0.9-km radius circle (<1 mi/mi2).
49

Management 

Implications

Table 29—Cumulative effects analysis for waterfowl and colonial 

nesting bird habitats for watersheds in the case study area

Percentage of habitat within Relative

Watershed a zone of influence rankinga

Chelan 34 Moderate

Chiwawa 55.1 High

Entiat 62.9 High

White-Little Wenatchee 55 Moderate

Columbia River-Antoine 0 Low

Mad River 74.4 High

Columbia River-Navarre 50.5 High

Wenatchee River 68.3 High

Nason Creek 65.9 High

Columbia River-Entiat 4.4 Low

Icicle 55.9 High

Columbia River-Swakane 41.9 Moderate

Cle Elum 55.7 High

Peshastin 77.8 High

Mission Creek 46.5 Moderate

Yakima 58.4 High

Columbia River-Stemilt 67.8 High

Peshastin 66.7 High

Swauk-Naneum 81.4 High

a High level of human influence = .50 percent of the habitat in the watershed outside 

a zone of influence, moderate level of human influence = 30 to 50 percent of the 

habitat in the watershed outside a zone of influence, and low level of human influence 

= <30 percent of the habitat in the watershed outside a zone of influence.

wildlife species and should be given high restoration priority. Opportunities to restore 

these habitats could be identified during roads analysis (USDA FS 2000c) and considered in project-level evaluations. 

Primary cavity excavator habitats—The cumulative effects analysis of roads on 

habitats for primary cavity excavators showed that 90 percent of the assessment units 

ranked as a low level of human influence, and 10 percent ranked as a moderate level 

of human influence (table 30). Relative to other focal species habitats, cumulative 

effects do not seem to be a significant issue for primary cavity excavators within the 

assessment area. 

This section provides information on the current condition of wildlife habitat for focal 

species relative to the cumulative effects of linear recreation routes. This information 

can be used to determine the significance of cumulative effects as an issue at the project scale. For example, if a project is proposed within an assessment area ranked as 

currently having a high level of human influence, then cumulative effects would be an 

important issue to address. This issue could be addressed by using the assessment 

models described in this document. This section also provides an evaluation of baseline conditions to which project-level assessments can be tiered. Finally, this information can be used to identify priorities for restoration of important habitats. The most 

notable restoration needs based on this assessment are core areas for grizzly bears, 

late-successional habitat effectiveness, riparian habitat effectiveness, and wetland 

habitat effectiveness. 
50

Table 30—Cumulative effects analysis for primary cavity excavator 

habitats for watersheds located in the case study area

Percentage of habitat within Relative

Watershed a zone of influence rankinga

Chelan 6.7 Low

Chiwawa 13.6 Low

Entiat 21.0 Low

White-Little Wenatchee 7.8 Low

Columbia River-Antoine 6.5 Low

Mad River 29.2 Low

Columbia River-Navarre 45.1 Moderate

Wenatchee River 26.7 Low

Nason Creek 17.4 Low

Columbia River-Entiat 22.6 Low

Icicle 4.1 Low

Columbia River-Swakane 24.1 Low

Cle Elum 13.3 Low

Peshastin 28.9 Low

Mission Creek 15.3 Low

Yakima 23.9 Low

Columbia River-Stemilt 27.0 Low

Peshastin 9.2 Low

Swauk-Naneum 47.5 Moderate

a Low level of human influence = <30 percent of the habitat in the watershed within a 

zone of influence, moderate level of human influence = 30 to 50 percent of the habitat 

in the watershed within a zone of influence, and high level of human influence = >50 

percent of the habitat in the watershed within a zone of influence.

Some tools that can be used to restore habitat effectiveness are described in general 

terms below and are based on Knight and Gutzwiller (1995) and Colorado State Parks 

(1998). 

• Spatial separation of humans and wildlife in key habitats. This approach could be 

used to address situations where displacement/avoidance interactions have been 

identified for a wildlife species of management interest.

• Temporal separation of humans and wildlife at critical periods. This tool could be 

applied where the interaction of displacement at a specific site has been identified 

for a wildlife species of management interest.

• Human behaviors that reduce the effects of recreation on wildlife can be taught 

through information and education programs.

• Facilities designed with wildlife habitat values in mind. If wildlife habitat issues 

are identified in the early stages of projects, they can be addressed proactively 

through project design. Hopefully, the information provided in this assessment 

will help accomplish this. 

To proactively address wildlife conservation and recreation opportunities, we need to 

begin addressing these issues through our landscape-scale planning processes, such 

as forest-level planning. This will help in identifying important habitats for wildlife and 

recreational opportunities for humans. This process could be accomplished by using 

the following approach: 
51

Monitoring 

and Adaptive 

Management 

• Assess the existing level of influence that recreational activities have on wildlife 

habitats by applying the GIS models and establishing baseline conditions.

• Set compatible wildlife habitat goals and recreation goals through an interdisciplinary planning process.

• Gain further knowledge about wildlife and recreation interactions through an adaptive-management approach. This will require a high level of collaboration between 

managers and researchers to jointly develop scientifically credible monitoring.

• Adapt habitat and recreation goals based on new information. 

The following section provides a framework for how to approach adaptive management and monitoring. This framework will allow us to address the mutual goals of 

conserving wildlife species while providing recreation opportunities. These goals have 

many commonalities, not the least of which is the desire of people to experience wildlife during their recreational outings. 

Monitoring has been identified as an integral part of an adaptive-management approach to natural resource conservation (Christensen 1997; Christensen et al. 1996; 

Everett et al. 1994; Gaines et al. 1999; Gutzwiller 1991, 1993; Noss and Cooperrider 

1994). Monitoring is defined as the collection and analysis of repeated observations 

or measurements to evaluate changes in condition and progress toward meeting a 

management objective (Elzinga et al. 1998). Adaptive management is a systematic 

process for continually improving management policies and practices by learning from 

the outcomes of operational programs (Nyberg 1998). Adaptive management blends 

methods of scientific investigation with deliberate manipulations of managed systems. 

Adaptive management embodies a simple imperative: policies are experiments and 

we must learn from them (Lee 1993). 

Adaptive management shares much of its theoretical basis with similar concepts 

from other fields. Examples include the continuous improvement process in business 

(Deming 1986, Walton 1986), adaptive control process theory in engineering, and operations research and management (McLain and Lee 1996). An adaptive management 

approach is particularly useful when dealing with complex management questions and 

high levels of uncertainty (Nyberg 1998, Walters 1986), both of which confront natural 

resource managers. One set of complex issues fraught with uncertainty is the management dilemma of balancing recreational opportunities with the conservation of ecological functions and processes. It would seem that using an adaptive-management 

approach, coupled with credible monitoring, is critical to address these issues. 

Scientists can play an important role in adaptive management (Walters 1986), but it is 

the local resource professionals who must become “adaptive managers” if the promise 

of the concept is to be realized through its application to natural resource management 

issues (Nyberg 1998). As part of their everyday jobs, resource managers must be able 

to design and implement studies that produce reliable information about complex natural resource issues. 

The process for designing and implementing an adaptive management project involves seven steps (based on Elzinga et al. 1998): (1) complete background tasks, (2) 

develop objectives, (3) design and implement management, (4) design the monitoring 

methods, (5) implement monitoring, (6) report and use results, and (7) adapt management in light of monitoring results. These seven steps are described in detail below. 

An AdaptiveManagement and 

Monitoring Process
52

Step 1. Background tasks—This step involves compiling and reviewing existing information, including relevant management direction. Important decisions to be made 

at this step include what the priorities are for monitoring (e.g., focal species habitat 

or population), what resources are available for monitoring, appropriate temporal and 

spatial scales, and the intensity of the monitoring efforts. 

Step 2. Develop clear, well-defined objectives—At this step, general management 

goals and objectives are defined, and monitoring indicators are selected. The desired 

direction of change (e.g., a 10-percent increase in habitat effectiveness) is described, 

and specific timeframes for achieving the desired direction are identified. 

Step 3. Design and implement management—At this step, the project is implemented. It is important that monitoring be considered an integral part of the initial project 

design as opposed to an afterthought. 

Step 4. Design the monitoring method—This critical step involves identifying the 

sampling objectives and methods, defining sampling units, estimating the number 

of sampling units required, noting sampling frequency, and identifying the resources 

needed to carry out the monitoring. Randomization, stratification, and replication are 

important concepts to integrate into the monitoring methods and have implications for 

the types of statistical methods that can be used in data analyses. Identifying the likely 

statistical methods that will be used in analysis is also important at this step. Seeking 

peer review of the monitoring and statistical methods is very important and should be 

an integral part of this step. This step must be completed along with project design so 

that project and monitoring objectives are integrated. 

Step 5. Implement monitoring—This step includes the collection of field data, 

analysis of data after each measurement cycle, and evaluation of monitoring results. 

Periodic analysis after measurement cycles allows for adjustments to be made in the 

monitoring methods. 

Step 6. Report and use results—For monitoring and adaptive management to be 

successful, the results, and their applications, must be displayed to managers, interested parties, and decisionmakers. In addition, it is important to leave tracks for successors, as some monitoring may be long term. Seeking peer review of the analysis 

methods and results is very important and should be an integral part of this step. 

Step 7. Adapt management approaches given the monitoring results—If monitoring is irrelevant to how resources are managed, then this step is not useful. However, if 

monitoring is carried out in a way that views management approaches as experimental, is designed into projects at their inception, and is done in a scientifically rigorous 

manner, then it can be used to guide management of natural resources. 

Step 1. Background—There is a proposal to build a trail for motorized use in order to 

separate motorized from nonmotorized trail recreation. The project occurs in a roadless area designated for motorized and nonmotorized trail recreation and in a habitat 

reserve that emphasizes late-successional habitat for species associated with latesuccessional forest. The land allocations have two goals: provide recreation trail opportunities and maintain security habitat for late-successional species. The specific 

security habitat goals were described in the reserve assessment (USDA FS 1997), 

which called for managing toward a goal of a “high” level of security habitat, which is 

defined as >70 percent security habitat in the reserve. Application of the late-succesA Hypothetical AdaptiveManagement Plan 
53

sional habitat cumulative effects models (as presented in this document) resulted in a 

concern by the interdisciplinary team (IDT) in meeting recreation needs and maintaining habitat effectiveness for wildlife. This prompted the IDT to propose an adaptive 

management approach for this project. 

The focal species selected for monitoring include breeding birds associated with 

late-successional forests (brown creeper, pygmy nuthatch, white-breasted nuthatch, 

white-headed woodpecker) and the American marten. 

Step 2. Objectives—The management goal is to maintain or improve security habitat 

for species associated with late-successional forest while providing for trail recreation 

opportunities. The objective is to determine (1) if motorized trail use decreases habitat 

effectiveness for the focal species, and (2) if nonmotorized trail use decreases habitat 

effectiveness for the focal species. The indicators that will be monitored include (1) 

population indices for late-successional breeding bird species and American marten 

along the proposed motorized trail, along a nonmotorized hiking trail, and in an area 

with no trails; and (2) the zone of influence at which focal species may be affected by 

motorized and or nonmotorized trails, compared to control (trailess) areas. 

Monitoring will be implemented for two field seasons following construction of the trail. 

Monitoring could lead to several possible management changes. First, monitoring 

may indicate that cumulative effects models need to be revised. Second, if monitoring 

results in modifications to the cumulative effects models, then the cumulative effects 

of the current conditions (baseline conditions) will be reassessed based on the new 

information. Finally, monitoring results will be applied to the evaluation of any future 

project to assess habitat effectiveness for late-successional focal species in the habitat reserve. 

Step 3. Project design and implementation—Because the IDT wants to take an 

adaptive-management approach, they will craft the decision notice to implement the 

project in three phases. Phase 1 would construct the trails beginning the first field 

season following a final decision. Phase 2 will be the monitoring of focal species during two field seasons immediately after completion of the trail construction. Phase 3 

would include a final evaluation of the monitoring information and appropriate management adjustments to the cumulative effects model and reevaluation of the trail network 

within the habitat reserve to assess attainment of security habitat goals. This example 

shows how management decisions can be crafted to incorporate adaptive management. 

Step 4. Monitoring methods—Monitoring of birds would take place during two 

breeding seasons immediately following completion of trail construction. Methods 

will be based on Hickman (1990) and Miller et al. (1998) and include bird point count 

stations (Ralph et al. 1993) located on and at various distances from motorized and 

nonmotorized trails, and areas with no trails. A total of 72 point count stations will be 

located in similar habitats. A total of nine 150-m segments would be monitored, three 

each along the motorized, nonmotorized, and no-trail areas. Table 31 summarizes the 

number of bird point count stations at various distances from the trails that would be 

monitored. 

Monitoring of the American marten would rely on the track plate method from Zielinski 

and Kucera (1995) as modified by Foresman and Pearson (1998). Track plate monitoring would occur at various distances from the trails (table 31) and would include a total 
54

Table 31—Monitoring efforts for the hypothetical adaptive management trail project to 

address the effects of motorized and nonmotorized recreation trails on late-successional 

focal species

No trail Nonmotorized trail Motorized trail

Distance from trail (meters) 0 100 200 300 0 100 200 300 0 100 200 300

Bird point count stations (number) 6 6 6 6 6 6 6 6 6 6 6 6

Marten track plate stations (number) 6 6 6 6 6 6 6 6 6

of 54 monitoring stations conducted during two summer field seasons following trail 

construction. A total of nine 150-m segments within similar habitats would be monitored; three each along the motorized, nonmotorized, and no-trail areas. 

Analysis of variance will be used to compare the detection rates of the focal species at 

each distance from the trail and for each trail type. Alpha for significance testing would 

be set at 0.05. 

Step 5. Implement and monitor—District recreation specialists and wildlife biologists 

would work cooperatively to implement and monitor the trail projects as described in 

the adaptive-management plan and decision notice. 

Step 6. Report and use—The district biologists and recreation specialists would 

summarize their monitoring results and present them to the district leadership team. 

The monitoring results and report will be peer reviewed and published to assure accuracy and objectivity, and to make them available for others to use. 

Step 7. Management adjustments—Based on the monitoring results, the district 

leadership team will review the cumulative effects model and trail network within the 

habitat reserve to make adjustments to meet the goals for habitat effectiveness for 

late-successional wildlife species and to provide recreation opportunities. 

Monitoring that is well thought out can be used to validate the assumptions of the 

cumulative effects models developed in this assessment, and to gain a better understanding of the interactions between wildlife and recreation. The use of adaptive 

management allows managers to acknowledge uncertainties and information gaps but 

still move forward with project design and implementation. To implement an adaptive 

approach, researchers and managers will have to work closely together. But by learning as we go, through the use of monitoring for adaptive management, we will have a 

higher probability of accomplishing the mutual objectives of providing a highly effective 

wildlife habitat and offering recreation opportunities. 

This assessment was funded by the Interagency Committee for Outdoor Recreation 

and the USDA Forest Service. We thank John Lehmkuhl for this thoughtful input 

on how to approach such a complex evaluation. We also thank Jeff Krupka, Peter 

Morrison, Karl Halupka, and Bob Naney for their thorough reviews of this manuscript. 

Conclusion

Acknowledgments
55

When you know: Multiply by: To find:

Meters (m) 3.28 Feet

Kilometers (km) .62 Miles (mi)

Square kilometers (km2) .38 Square miles (mi2)

Hectares (ha) 2.47 Acres 

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Weaver, J.L.; Escano, R.E.; Winn, D.S. 1987. A framework for assessing cumulative 

effects on grizzly bears. Transactions of the North American Wildlife and Natural 

Resources Conference. 52: 364–376. 

Welsh, H.H., Jr.; Ollivier, L.M. 1998. Stream amphibians as indicators of ecosystem 

stress: a case study from California’s redwoods. Ecological Applications. 8(4): 

1118–1132. 

Wemmer, C.; Kunz, T.H.; Lundie-Jenkins, G.; McShea, W.J. 1996. Mammalian 

sign. In: Wilson, D.E.; Russel, C.F.; Nichols, J.D. [et al.], eds. Measuring and 

monitoring biological diversity: standard methods for mammals. Washington, DC: 

Smithsonian Institution Press: 157–176. 

Werschkul, D.F.; McMahon, E.; Leitschuh, M. 1976. Some effects of human 

activities on the Great Blue Heron in Oregon. The Wilson Bulletin. 88(4): 660–662. 

White, G.C.; Garrott, R.A. 1990. Analysis of wildlife radio-tracking data. New York: 

Academic Press. 383 p.

Wisdom, M.J.; Hargis, C.D.; Holthausen, R.S. [et al.]. 1999. Wildlife habitats 

in forests of the interior Northwest: history, status, trends, and critical issues 

confronting land managers. Transactions of the North American Wildlife and Natural 

Resources Conference. 64: 79–93. 

Wisdom, M.J.; Holthausen, R.S.; Wales, B.C. [et al.]. 2000. Source habitats for 

terrestrial vertebrates of focus in the interior Columbia basin: broad-scale trends 

and management implications. Gen. Tech. Rep. PNW-GTR-485. U.S. Department 

of Agriculture, Forest Service. 529 p. 3 vols.

Yanes, M.; Velasco, J.M.; Suarez, F. 1995. Permeability of roads and railways to 

vertebrates: the importance of culverts. Biological Conservation. 71: 217–222.

Zielinski, W.J.; Kucera, T.E., tech. eds. 1995. American marten, fisher, lynx and 

wolverine: survey methods for their detection. Gen. Tech. Rep. PSW-GTR-157. 

Albany, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest 

Research Station. 163 p.
71

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

Amphibians

Northwestern salamanderLong-toed salamanderPacific giant salamanderLarch Mountain salamanderRoughskin newtWestern toadPacific treefrogTailed frog*Cascade frog*Spotted frog

Reptiles

Northern alligator lizardWestern fence lizardWestern skinkRubber boaRacerSharptail snakeNight snakeGopher snakeWestern terrestrial garter snakeCommon garter snakeWestern rattlesnake

Birds

Arctic loonCommon loon*Yellow-billed loonPied-billed grebeHorned grebeRed-necked grebeEared grebe*Western grebeAmerican white pelicanDouble-crested cormorantAmerican bitternGreat blue heron*Great egretCattle egretGreen-backed heronBlack-crowned night heronTundra swanTrumpeter swanGreater white-fronted gooseSnow gooseCanada goose

X X X X X X XX X X X X XX X X X X X X

X

X X X X X X XX X X X X XX X X X X XX X X X X X X XX X X X X XX X X X X X

X X X X

X X X X X

X X X XX X X X

X X X X X

X X X X X X

X X X X

X X X X XX X X X XX X X X X

X X X X

XX X X X X X XXXXXX X X X X X XXXXX XX X X X X X X XX XX XX XX XXX XXX XX X
72

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

Birds (continued)

Wood duck*Green-winged tealAmerican black duckMallardNorthern pintailBlue-winged tealCinnamon tealNorthern shovelerGadwallEurasian wigeonAmerican wigeonCanvasbackRedheadRing-necked duckGreater scaupLesser scaupHarlequin duck*OldsquawSurf scoterWhite-winged scoterCommon goldeneyeBarrow’s goldeneyeBuffleheadHooded merganserCommon merganserRed-breasted merganserRuddy duckTurkey vultureOspreyBald eagle*Northern harrierSharp-shinned hawkCooper’s hawkNorthern goshawk*Swainson’s hawkRed-tailed hawkFerruginous hawkRough-legged hawkGolden eagleAmerican kestrelMerlinPeregrine falconGray falconPrairie falconGray partridgeChukar

X X X X X X X X XXXX XXXXXXXXXXXXX

X X X X X X X X X X X X X X

XXXX

X XX XX XX X X

XX

X X XX X X X X X X X 

X X

X X XX X XX X X X X X X X X

X XX X

X X X X X X X

X X X XX X X XX XX XX X X X

X XX X
73

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

Birds (continued)

Ring-necked pheasantSpruce grouseBlue grouseWhite-tailed ptarmiganRuffed grouseSage grouseSharp-tailed grouseNorthern bobwhiteCalifornia quailMountain quailVirginia railSoraAmerican cootSandhill craneBlack-bellied ploverSemi-palmated ploverKilldeerMountain ploverBlack-necked stiltAmerican avocetGreater yellowlegsLesser yellowlegsSolitary sandpiperWilletSpotted sandpiperUpland sandpiperWhimbrelLong-billed curlewBar-tailed godwitMarbled godwitRuddy turnstoneRed knotSanderlingSemi-palmated sandpiperWestern sandpiperLeast sandpiperWhite-rumped sandpiperBaird’s sandpiperPectoral sandpiperDunlinStilt sandpiperBuff-breasted sandpiperShort-billed dowitcherLong-billed dowitcherCommon snipeWilson’s phalarope

X

X

X

X

X

X

X

X

X

X

XX

X

X

X

XX

X

X

XXXX

X

XXXXXXXXXXXXXXXXX

X

XXXXXXXXX

X

X

X

X

X
74

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

Birds (continued)

Red-necked phalaropeLong-tailed jaegerFranklin’s gullBonaparte’s gullRing-billed gullCalifornia gullHerring gullGlaucous-winged gullGlaucous gullSabine’s gullIceland gullCaspian ternCommon ternForster’s ternBlack ternMarbled murreletRock doveBand-tailed pigeonMourning doveYellow-billed cuckooBarn owlFlammulated owlWestern screech-owlGreat horned owlSnowy owlNorthern hawk-owlNorthern pygmy-owlBurrowing owlNorthern spotted owl*Barred owlGreat gray owlLong-eared owlShort-eared owlBoreal owlNorthern saw-whet owlCommon nighthawkCommon poorwillBlack swiftVaux’s swiftWhite-throated swiftBlack-chinned hummingbirdAnna’s hummingbirdCalliope hummingbirdRufous hummingbirdBelted kingfisherLewis’s woodpecker

xxxxx xxxxxxxxxxx

x

x

xx xx xx

x x x x

xxx x

x x x x

x x x x x x x

x x

x x

xx x x x

x x

x x xxx x x xxxxxxx x

x x x
75

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

Birds (continued)

Red-breasted sapsuckerWilliamson’s sapsuckerDowny woodpeckerHairy woodpeckerWhite-headed woodpecker*Three-toed woodpecker*Black-backed woodpeckerNorthern flickerPileated woodpecker*Olive-sided flycatcherSay’s phoebeWestern wood-peweeWillow flycatcherLeast flycatcherHammond’s flycatcherDusky flycatcherGray flycatcherWestern flycatcherAsh-throated flycatcherWestern kingbirdEastern kingbirdHorned larkTree swallowViolet-green swallowNorthern rough-winged swallowBank swallowCliff swallowBarn swallowGray jayStellar’s jayScrub jayPinyon jayClark’s nutcrackerBlack-billed magpieAmerican crowCommon ravenBlack-capped chickadee*Mountain chickadeeChestnut-backed chickadeeBushtitRed-breasted nuthatchWhite-breasted nuthatch*Pygmy nuthatch*Brown creeper*Rock wrenCanyon wren

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

XX

X

X

XXX

X

X

X

XX

X

X

X

XXX

X

X

X

X

X

XXXX

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X
76

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

Birds (continued)

Bewick’s wrenHouse wrenWinter wrenMarsh wrenAmerican dipperGolden-crowned kingletRuby-crowned kingletWestern bluebirdMountain bluebirdTownsend’s solitaireVeerySwainson’s thrushHermit thrushAmerican robinVaried thrushGray catbirdNorthern mockingbirdSage thrasherAmerican pipitBohemian waxwingCedar waxwingNorthern shrikeLoggerhead shrikeEuropean starlingSolitary vireoWarbling vireoRed-eyed vireoOrange-crowned warblerNashville warblerYellow warblerYellow-rumped warblerBlack-throated gray warblerTownsend’s warblerHermit warblerPalm warblerBlack-and-white warblerAmerican redstartNorthern waterthrushMacgillivray’s warblerCommon yellowthroatWilson’s warblerYellow-breasted chatWestern tanagerBlack-headed grosbeakLazuli buntingSpotted towhee

X

X X X X X

XX

X X X X

X

X

X X X X

X X X

X X

X X

X X

X

X X X

X X

X

X XX X X X XX X X X XX X X XXXX X X X XX X X X

X

X X

X

X X X X

X X X

XX X X X XX XX X X XXXXX
77

Birds (continued)

American tree sparrowChipping sparrowClay-colored sparrowBrewer’s sparrowVesper sparrowLark sparrowSage sparrowSavannah sparrowGrasshopper sparrowFox sparrowSong sparrowLincoln’s sparrowWhite-throated sparrowGolden-crowned sparrowWhite-crowned sparrowHarris’s sparrowDark-eyed juncoLapland longspurSnow buntingBobolinkRed-winged blackbirdWestern meadowlarkYellow-headed blackbirdBrewer’s blackbirdBrown-headed cowbirdNorthern oriole (Bullock’s)Rosy FinchPine grosbeakPurple finchCassin’s finchHouse finchRed crossbillWhite-winged crossbillCommon redpollPine siskinAmerican goldfinchEvening grosbeakHouse sparrow

Mammals

Virginia opossumMasked shrewMerriam shrewTrowbridge shrewDusky shrewMontane shrew

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

XXXXXX

X

X

XX

X

X

X

X

X

X

XXXX

X

X

XX

X

X

X

XX

XX

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X
78

Mammals (continued)

Northern water shrewPygmy shrewVagrant shrewWater shrew*Shrew-moleCoast mole (Pacific)Little brown myotisYuma myotisKeen myotisLong-eared myotisFringed myotisLong-legged myotisCalifornia myotisSilver-haired batSmall footed pipistrelBig brown batHoary batTownsend’s big-eared bat (western)Black bearGrizzly bear*RaccoonMarten*Fisher*Ermine (shorttail weasel)Longtail weaselMinkWolverine*River otterBadgerWestern spotted skunkStriped skunkCoyoteGray wolf*Red foxMountain lionLynx*BobcatMountain beaverYellowbelly marmotHoary marmotCalifornia ground squirrelTownsend ground squirrelGolden-mantled ground squirrelLeast chipmunkTownsend chipmunkYellow pine chipmunk

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

XX

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

X

XXX

X

X

X

X

X

X

X

X
79

Mammals (continued)

Western gray squirrelDouglas squirrel (chickaree)Northern flying squirrel*Northern pocket gopherGreat Basin pocket mouseBeaverWestern harvest mouseDeer mouseBushytail woodratHeather vole (mtn. phenacomys)Redback vole (boreal)Meadow voleWater vole (Richardson vole)Creeping vole (Oregon vole)Longtail voleSagebrush voleMuskratNorway ratHouse mouseWestern jumping mousePacific jumping mousePorcupineNutriaPikaWhitetail jackrabbitSnowshoe hareBlacktail jackrabbitMooseCottontail (mountain)Rocky mountain elk*Mule deer*Whitetail deerMountain goat*Bighorn sheep*

Mollusks

Warty jumping slugBlue-gray taildropperPapillose taildropperChelan mountain snailColumbia pebblesnail

Riparian-associated

Late successional

Primary cavity excavator

Waterfowl (lakes, ponds, etc.)

Ungulates

Wide-ranging carnivores

Snag reduction

Down log reduction

Edge effects

Hunting

Trapping

Poaching

Collection

Disturbance at a specific site

Collisions

Negative human interactions

Movement barrier filter

Displacement/avoidance

Habitat loss/fragmentation

Physiological response

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Hunting

Snag reduction

Trapping

Poaching

Collection

Edge effects

Collisions

Disturbance at a specific site

Negative human interactions

Movement barrier

Displacement/avoidance

Habitat loss/fragmentation

Route for comptetitors/predators

Trapping

Direct mortality

Wildlife 

groups Road-associated factors

Nonmotorized trailassociated factors Motorized trail- associated factors W

X X X X

X XX X X X X XX X

X X X X X X X X X 

X X X X X X X X X X X X XX XX X X XX X X X

X

X X X

X X

X X

X

X X

X X

X X X X X X X X X X X X X

X

X X XX XX XXX

XX 

X X X

X X X X X X X X X X X X X X X 

X X X X X X X X X X X X X X X X X X X X X X X X X X X X X XX X X X X X X X X X X X X X X 

X X XX X XX X XX X XX X X

* indicates species that were used as focal species.
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