Willamette Valley 

Conservation Study

Strategic Habitat Conservation 

in Oregon’s Willamette Valley

U.S. Fish & Wildlife Service

Willamette Valley Conservation Study 

Strategic Habitat Conservation 

in Oregon’s Willamette Valley 

March 2017 

Prepared by the: 

U.S. Department of the Interior 

Fish and Wildlife Service 

911 NE 11th Avenue 

Portland, Oregon 97232 

Recommended citation: U.S. Fish and Wildlife Service. 2017. Willamette Valley Conservation 

Study. Pacific Region, Portland, Oregon. 148 pp. 
 
Willamette Valley Conservation Study 

Strategic Habitat Conservation In Oregon’s Willamette Valley i 

Executive Summary 

Oregon’s Willamette Valley, renowned for the high quality of life it affords its residents, is losing 

part of its natural heritage. Habitat loss and fragmentation coupled with the loss of disturbance 

regimes that rejuvenated and maintained native habitats has resulted in population declines of many 

of the valley’s sensitive wildlife and plants. Several Willamette Valley species are currently listed 

under the State or Federal endangered species acts. 

There is a long history of partners working together to address these issues, through land-based and 

educational conservation actions across the valley. To determine where and how the U.S. Fish and 

Wildlife Service could complement these actions, we worked with the Oregon Department of Fish 

and Wildlife, and other governmental and non-governmental organizations engaged in conservation 

efforts in the Willamette Valley to complete a study of land-based conservation needs and 

opportunities in the valley. For the purposes of this study, land-based conservation includes actions 

to identify, preserve, restore, and manage terrestrial areas primarily for their wildlife habitat values 

while promoting nature-based recreational and educational activities where appropriate. 

The study concludes that the amount and distribution of lands currently managed for sensitive, native 

wildlife species is inadequate for depressed populations to recover to a healthy and viable condition 

across their range in the valley. The study recommends that networks of grasslands, oak woodlands, 

and riparian habitats in specific areas of the valley—subsets of Conservation Opportunity Areas 

identified by the Oregon Department of Fish and Wildlife, be provided as safe and secure habitat to 

allow populations of sensitive native wildlife and plants space and time to recover. Establishing these 

habitat networks provides an opportunity to reclaim a portion of the valley’s natural heritage for 

current and future generations of Oregonians to experience and enjoy. 

 
Willamette Valley Conservation Study 

ii Strategic Habitat Conservation In Oregon's Willamette Valley 

Acronyms 

Acronym Full Phrase 

BLM Bureau of Land Management 

CCAA Candidate Conservation Agreements with Assurances 

CLI Climate Leadership Institute 

COA Conservation Opportunity Area 

COLT Coalition of Land Trusts 

GIS Geographic Information System 

GLT Greenbelt Land Trust 

NEAT National Ecological Assessment Team 

NWR National Wildlife Refuge 

NWRS National Wildlife Refuge System 

OCCRI Oregon Climate Change Research Institute 

OCS Oregon Conservation Strategy 

ODAS Oregon Department of Administrative Services 

ODFW Oregon Department of Fish and Wildlife 

ODOT Oregon Department of Transportation 

OPB Oregon Progress Board 

PAD-US Protected Area Database – United States 

PCA Priority Conservation Area 

SHA Safe Harbor Agreement 

SHC Strategic Habitat Conservation 

TNC The Nature Conservancy 

USDC United States Department of Commerce 

USDI United States Department of the Interior 

USFWS United States Fish and Wildlife Service 

UW University of Washington 

WGWC Western Governors’ Wildlife Council 

WVCS Willamette Valley Conservation Study 

T 

 
Willamette Valley Conservation Study 

Strategic Habitat Conservation In Oregon’s Willamette Valley iii 

Table of Contents 

Executive Summary .....................................................................................................................ES-1 

Acronyms/Abbreviations .............................................................................................................. A-1 

Introduction ........................................................................................................................................ 1 

The Study ........................................................................................................................................... 4 

The Willamette Valley Today ............................................................................................................ 5 

Native Species and Habitats ........................................................................................................ 5 

A Changing Climate .................................................................................................................... 6 

Connecting People with Nature ................................................................................................... 7 

The Crucial Role of Private Landowners .................................................................................... 8 

Strategic Habitat Conservation .......................................................................................................... 9 

Biological Planning ..................................................................................................................... 9 

Selecting Conservation Targets ............................................................................................. 9 

Other Species of Conservation Concern ...................................................................................... 12

Establishing Biological Objectives ........................................................................................ 12 

Establishing Habitat Objectives ............................................................................................ 13

Habitat Objectives ................................................................................................................. 15 

Other Species of Conservation Concern ................................................................................ 17 

Conservation Design .................................................................................................................... 17 

Identifying Priority Areas for Conservation .......................................................................... 17 

GAP Analysis .............................................................................................................................. 18 

Threats Analysis .......................................................................................................................... 20 

Discussion .................................................................................................................................... 21 

Recommendations .............................................................................................................................. 23 

Conclusion ................................................................................................................................... 27 

Appendices 

Appendix A. Willamette Valley Conservation Plans ......................................................................... A-1 

Appendix B. Climate Change ............................................................................................................ B-1 

Appendix C. Priority Habitats ............................................................................................................ C-1 

Appendix D. Selection Criteria .......................................................................................................... D-1 

Appendix E. Population and Habitat Objectives ............................................................................... E-1 

Appendix F. Marxan .......................................................................................................................... F-1 
Willamette Valley Conservation Study 

iv Strategic Habitat Conservation in Oregon’s Willamette Valley 

Appendix G. Priority Conservation Areas ......................................................................................... G-1 

Appendix H. GAP Analysis ............................................................................................................... H-1 

Appendix I. Threats Analysis............................................................................................................. I-1 

Appendix J. Literature Cited .............................................................................................................. J-1 

Appendix K. Planning Team .............................................................................................................. K-1 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 1 

Introduction 

Oregonians have long recognized the value of the Willamette Valley for people—its abundant clean 

water, mild climate, and rich soils make the valley an important agricultural center. Its cities and 

towns, with their high livability standards and close proximity to outstanding recreational 

opportunities continue to draw new residents. From 1970 to 2010, the population of the counties in 

the valley grew by about 86 percent—from just under 1.5 million to about 2.7 million. The State of 

Oregon projects an additional 1.3 million new residents by 2050, an increase of about 178 percent 

since 1980. The 1.3 million new residents represents a population that is larger than today’s 

combined populations of Portland, Eugene, Salem, Gresham, Hillsboro, Beaverton, Medford, Bend, 

Springfield, and Corvallis—the ten largest cities in Oregon (ODAS 2013). 

In 2000, the State of Oregon published the Oregon State of the Environment 2000 report (OPB 

2000). The report was the first scientifically credible, comprehensive assessment of Oregon’s 

environment. Signed by all of Oregon’s former governors alive at the time (Hatfield, Straub, Roberts, 

Atiyeh, Goldschmidt, and Kitzhaber), the report concluded that “One of Oregon’s greatest 

environmental challenges for this century lies in the Willamette Valley. Transformation of prairies, 

woodlands, riparian areas, and rivers of the valley has fueled our economic growth for over 150 

years. Yet this transformation has left its mark on our environment and a debt to pay. Whether we 

can improve the ecological health of the valley, measured currently by recovery of salmon and 

watersheds, while continuing economic growth and development for home and communities will be a 

stern environmental test.” 

The Willamette Valley constitutes the southern extent 

of a larger inland ecosystem flanked by the Cascade 

Mountains to the east and the coastal mountains of 

Oregon, Washington, and British Columbia to the 

west. With its prairie and oak components, this system 

creates a stark contrast to the surrounding landscape 

dominated by coniferous forests. This uniqueness 

represents a vital part of Oregon’s biodiversity and the 

valley’s natural heritage, featuring a high degree of 

species and habitat specialization that is far different 

from that found in the surrounding matrix of 

coniferous forests (Altman and Stephens 2012). 

At the time of Euro-American settlement, which 

began in earnest only a little more than 150 years ago, 

the valley was typically described as a landscape 

dominated by vast open prairies interspersed with 

solitary oak and pine trees. The open prairies were 

surrounded by bands of oak woodlands. Closedcanopy coniferous forests were limited to the upper 

foothills and beyond (Johannessen et al. 1971; Christy 

and Alverson 2011). The valley’s major rivers were 

lined by wide extents of hardwood forests and 

shrublands, which experienced flooding on an annual 

basis (Hulse et al. 2002). 

Figure 1. Historical vegetation classes in the 

Willamette Valley based on General Land 

Survey Office data, 1851-1910 (Christy and 

Alverson 2011, used with permission). 
Willamette Valley Conservation Study 

2 Strategic Habitat Conservation in Oregon’s Willamette Valley 

For millennia, the prairies were maintained free of encroaching trees and shrubs by frequent, low 

severity fires set by the native Kalapuya people. Burning increased the distribution and quantity of 

food that could be harvested by increasing oak and filbert production, stimulating berry and root 

production (especially in the extensive camas prairies), and concentrating deer for hunting (Taft and 

Haig 2003, Connolly 2000, Johannessen et al. 1971, Hamman et al. 2011). Annual springtime 

flooding along the Willamette River rejuvenated and maintained complex riverine and floodplain 

habitats (Hulse et al. 2002). 

As settlers arrived in the valley, malaria and other introduced diseases ravaged the Kalapuya, and as 

more settlers moved in, the remaining Kalapuya were driven out (Connolly 2000, Taft and Haig 

2003). Ranching, farming, and logging practices were introduced (Christy and Alverson 2011) and 

the practice of annual burning was greatly curtailed (Taft and Haig 2003, Hamman et al. 2011, 

Johannessen et al. 1971). As burning was curtailed, the habitats changed (Connolly 2000). Oak 

densities increased and conifers began to invade the open prairies and savannas, which over time, 

converted to closed-canopy forests (Christy and Alverson 2011, ODFW 2006). As the number of 

settlers increased, annual flooding posed an ever increasing risk to life and property. To abate the 

risk, dams were built and revetments were constructed along the river’s banks. 

Habitat loss and fragmentation is an ongoing issue in the valley. A study of natural area loss 

conducted across 11 western states used public datasets to assess the degree of human modification 

to natural areas from 2001 to 2011 (Center for American Progress 2016). The conversion from 

natural areas to developed areas during this time period in the nine counties of the WVCS sums to 

almost 61,500 acres (Table 1). (The conversion to development was calculated by county area and so 

it includes some areas outside of the Willamette Valley Level III Ecoregion, the WVCS study area). 

Of particular note, however, is that in seven of the nine counties, the annual rate of conversion is 

much higher than statewide and west-side conversion rates. 

In Table 1, figures in red are rates of loss higher than the average annual rates, figures in blue are 

lower than average annual rates. For example, the rate of natural area conversion in Washington 

County was 198 percent higher than the average statewide rate, while the natural areas conversion 

rate in Lane County was 19.4 percent lower than the combined rates of the 11 western states. 

Table 1: Natural Area Development 2001-2011 

County 

Natural Areas 

Developed as of 

2011 (acres) 

Percent of 

County 

Natural Areas 

Developed 

2001-2011 

(acres) 

Rate of Natural Area Development 

Compared to: 

Oregon's 

Average Annual 

Rate1

Western States 

Average Annual 

Rate1

Multnomah 119,244 43.3% 3,718 213.5% 232.0% 

Washington 175,711 38.0% 6,583 198.0% 215.6% 

Yamhill 154,667 33.9% 4,328 87.6% 98.7% 

Clackamas 269,447 22.6% 11,734 66.9% 76.7% 

Polk 142,438 30.1% 4,124 63.8% 73.0% 

Marion 258,597 34.2% 4,779 26.0% 33.4% 

Linn 306,171 20.9% 9,479 7.9% 14.3% 

Benton 106,150 24.6% 2,223 9.8% 4.6% 

Lane 390,050 13.4% 14,508 24.0% 19.4% 

Oregon State 8,219,358 13.4% 263,418 - 10.3 

1 = Figures in red are higher than average annual rates, figures in blue are lower than average annual rates. 

Source: Center for American Progress, 2016 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 3 

The ongoing conversion of natural areas and the exclusion of fire and reduced flooding had, and 

continues to have, a marked effect on the valley’s native habitats and the wildlife they support. The 

vast prairies, savannas, oak woodlands, and riparian forests and shrublands that once dominated the 

valley’s landscape are now highly diminished, degraded, and fragmented, and no longer capable of 

supporting some of Oregon’s iconic wildlife. 

Native species and ecosystems may be at an ecological tipping point, as evidenced by the declining 

populations and range contractions of many native fish, wildlife, and plant species. Twelve species 

native to the valley are listed under the federal Endangered Species Act (ESA). Many species are 

extirpated from the valley, and many more are threatened with extirpation including the State Bird of 

Oregon, the western meadowlark (ODFW 2008). The projected human population growth will only 

increase the need for additional outputs from the valley’s working landscapes, putting ever more 

pressure on the limited remaining natural areas. 
Willamette Valley Conservation Study 

4 Strategic Habitat Conservation in Oregon’s Willamette Valley 

The Study 

The purpose of the Willamette Valley Conservation Study (WVCS) is to assess what will be needed 

to achieve the conservation of a suite of species that represent native habitats within the Willamette 

Valley, and how the Service could compliment on-going conservation actions being carried out by 

private landowners and multiple agencies and nongovernmental organizations across the valley. This 

study follows the U.S. Fish and Wildlife Service’s (Service) Strategic Habitat Conservation (SHC) 

protocol. SHC is the Service’s approach for the efficient conservation of wildlife populations with 

the overall goal of maintaining landscapes capable of supporting healthy, self-sustaining populations 

of native fish, wildlife, and plants (USFWS 2008a). 

To add a surrogate species approach to conservation in the Willamette Valley, the Service convened 

a Willamette Valley Strategic Conservation Management Team, comprising many conservation 

partners active in the Willamette Valley. Surrogate species are “species that are used to represent 

other species or aspects of the environment to obtain a conservation objective” (Caro 2010). Caro 

noted that species are selected for different reasons: (1) to document the effects of environmental 

change on biological systems; (2) for use in public relations exercises to promote understanding of 

environmental problems and (3) to locate areas of conservation significance. The Willamette Valley 

Surrogate Species Pilot (USFWS 2014) selected species for the first two reasons. The WVCS 

compliments and builds upon the pilot by selecting species for the third reason—to locate areas of 

conservation significance. 

The WVCS also incorporates and builds upon the Comprehensive Conservation Plans recently 

completed for the National Wildlife Refuges in the valley (USFW 2011, USFWS 2013a), and the 

Oregon Department of Fish and Wildlife’s (ODFW) Oregon Conservation Strategy (OCS) (ODFW 

2006, ODFW 2016). It also incorporates many of the recommendations from other studies and plans 

that have shaped conservation actions in the valley. These plans are summarized in Appendix A. 

The study area is a modified version of the Willamette Valley Level III Ecoregion as defined by 

Omernik (1987) and the Environmental Protection Agency (1999) (Figure 1.1). The study excluded 

the portion of the ecoregion in Washington State as well as lands along the Columbia River that are 

included in other similar studies. The study covers approximately 5,000 square miles, extending 120 

miles north to south and ranging from 20 to 40 miles in width. It includes the six largest cities in 

Oregon (Portland, Eugene, Salem, Gresham, Hillsboro, and Beaverton) as well as portions of Benton, 

Clackamas, Lane, Linn, Marion, Multnomah, Polk, Washington, and Yamhill counties. 

 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 5 

The Willamette Valley Today 

Native Species and Habitats 

It takes time for species to adjust to changed conditions, and from an ecological and evolutionary 

standpoint, 150 years is just the blink of an eye. Significant habitat loss and fragmentation coupled 

with the invasion of noxious, non-native plants and animals and the loss of the fires and floods that 

rejuvenated and maintained the habitats has had pronounced effects on the wildlife and plants they 

support, or once supported. 

Today, species are still adjusting and for many, the adjustment isn’t going particularly well. Evidence 

of this is found in the fact that there are now 12 species of fish, wildlife, and plants native to the 

valley whose population numbers are so low that they are listed as threatened or endangered under 

the federal Endangered Species Act (USFWS 1993a, 1997, 1998a, 2000, 2013b). Two other 

federally-listed species, the Oregon spotted frog and yellow billed cuckoo, historically bred in the 

valley, but are now extirpated. Many other species including western meadowlark, Oregon vesper 

sparrow, and yellow-breasted chat are considered by the State of Oregon to be threatened with 

extirpation from the valley (ODFW 2008). Grassland-dependent birds have suffered steep population 

declines and severe range contractions as they adjust to the new realities of the valley (Altman 1999, 

ODFW 2010). ODFW found that “In Oregon’s Willamette Valley, many grassland species have 

exhibited steady downward trends in distribution and abundance, with some likely having been 

extirpated as a breeding species” (ODFW 2010). 

Rather than living in single, large, interacting populations, wildlife inhabiting areas with fragmented 

habitats are often structured into groups of local subpopulations based on the number, size, and 

distribution of habitat patches suitable for meeting their life-history requirements (e.g., successful 

breeding, rearing young, foraging, etc.). A habitat patch is simply a distinct area of a particular 

vegetation type (e.g., riparian forest, oak woodland). A group of local subpopulations that interact 

with one another is referred to as a metapopulation (Hanski and Gilpen 1991, Hanski 1998, 

Akҫakaya et al. 2007). Species occurring as metapopulations, depend on a network of habitat patches 

to occur on the landscape that meet their minimum requirements in terms of number, size, quality, 

and distribution, to ensure their long-term persistence. If the network of habitat patches meets the 

requirements, the metapopulation persists. If not, the metapopulation will decline and eventually be 

lost (Hanski and Ovaskainen 2002). 

Based on documented valley-wide population declines and range contractions, it is reasonable to 

conclude that the valley’s current configuration of habitat within which wildlife can breed and raise 

their young free from other land management conflicts is inadequate for depressed populations of 

many of its imperiled species to recover and ensure their long-term persistence. By not expressly 

directing sufficient conservation actions on their behalf, we may be allowing these species to follow 

Columbian white-tailed deer, Oregon spotted frog, yellow-billed cuckoo, burrowing owls, lark 

sparrows, and many others as species now extirpated from the valley. 

Wintering Canada Geese 

On the other side of the population trend ledger are wintering Canada geese, the wintering population 

in the valley has greatly increased over the past several decades. In the mid-1960s, approximately 

15,000-25,000 Canada geese wintered in the Willamette Valley/Lower Columbia River region of 
Willamette Valley Conservation Study 

6 Strategic Habitat Conservation in Oregon’s Willamette Valley 

Oregon and Washington (Pacific Flyway Council 2008). The majority of these geese were dusky 

Canada geese (Branta canadensis occidentalis). The Willamette Valley NWR Complex was created 

during this timeframe, primarily to provide winter forage and sanctuary for dusky Canada geese. 

Since then, the dusky Canada goose population has fallen to about half its historic levels (Pacific 

Flyway Council 2008), while at the same time other subspecies of Canada geese have increased 

substantially. Currently, an estimated 350,000 Canada geese winter in the Willamette Valley/Lower 

Columbia River region (USFWS 2014b). The majority of the wintering goose population is 

comprised of cackling geese (Branta hutchinsii minima). Cackling geese breed in western Alaska and 

historically wintered in California, but beginning in the 1990s, the majority of the cackling geese 

population shifted from their historic winter range to the Willamette Valley (Pacific Flyway Council 

1999). Cackling goose numbers have the potential to increase which would undoubtedly result in 

increased numbers of geese wintering in the Willamette Valley. 

Approximately 6,550 acres of NWRS lands are currently dedicated to providing forage for wintering 

geese. ODFW manages two state wildlife areas within the Willamette Valley (E.E. Wilson and Fern 

Ridge) with about 100 acres of those areas provide goose forage. While these lands are managed to 

provide high quality food and sanctuary, they are far from sufficient to support all of the Canada 

geese currently wintering in the area (Mini 2012). Private lands, especially grass seed, wheat, 

pasture, and other grain and forage crops are playing a major role in providing food for wintering 

geese. However, the provision of these crops comes at a cost to the farming community in the form 

of crop depredation. Current goose management programs have had varying degrees of success, but 

even cumulatively, they have not been adequate to limit crop depredation on private lands. 

A Changing Climate 

A changing climate adds additional uncertainty to the equation. Although climate change is almost 

certain to affect the Willamette Valley (OCCRI 2010; Schafer et al. 2001), there is uncertainty about 

the direction and specific consequences it will have to its species and habitats. The University of 

Washington (UW) studied the potential effects of a changing climate on the Willamette Valley and 

their results indicate a trend toward warmer and wetter winters, and hotter and drier summers 

(Michalak et al. 2013). 

Climate change can put a species at risk if the climatic conditions within which the species persists 

(i.e., its climate envelope) moves outside of the species’ current geographic range. A climate 

envelope is modeled by associating aspects of the climate with a species’ range to estimate the 

conditions and identify the areas that are suitable to maintain that species (Araújo and Peterson 

2012). If a species’ climate envelope shifts outside its current range, the species is at risk. The 

magnitude of the risk depends on how quickly the climate envelope shifts relative to the species 

ability to respond. 

UW developed climate envelop models for several species of conservation concern in the valley and 

found that relatively few significant changes are expected. This finding suggests that average 

projected climate changes do not exceed the range of climate conditions currently tolerated by most 

of the priority conservation species in the valley (Michalak et al. 2013). Warmer, drier summer 

conditions leading to increased summer drought may actually benefit the relatively drought-tolerant 

native prairie and savanna species over the less drought-tolerant tree and other forest species, 

possibly resulting in prairie/savanna expansion (Bachelet et al. 2011). 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 7 

This is not to suggest climate change will not adversely affect the valley’s sensitive wildlife. Species 

with limited dispersal abilities, such as the endangered Fender’s blue butterfly may not be capable of 

redistributing to new areas with suitable conditions if their current locations become unsuitable. The 

combination of decreased summer flow volumes in rivers and streams and increased air temperatures 

will almost certainly lead to increases in summer water temperature (OCCRI 2010) which could have 

profound effects on a wide range of species, including aquatic insects, fish, and amphibians. 

In a study of grassland bird reproduction in shortgrass prairies, Conrey et al., (2016) found increased 

nestling mortality following very hot days and droughty days. Large storm events also resulted in 

increased nestling mortality. Across the 10 years of their study, they found lower survival rates 

during warmer and drier breeding seasons compared to average conditions. Hotter and drier summers 

are forecast for the Willamette Valley and short-term (3-month) droughts will be increasingly more 

likely (Jung and Chang 2011). The extent to which grassland bird populations are affected by these 

changes remains to be seen, but species with low population numbers are already at an increased risk 

of extirpation and anything that reduces juvenile survival rates only magnifies that risk. 

Perhaps one of the greatest threats to the Willamette Valley due to the changing climate is the likely 

immigration of people (climate migrants or climate refugees) to the valley, over and above the 

already anticipated rapid population growth. The Climate Leadership Initiative of the University of 

Oregon’s Institute for a Sustainable Environment (CLI 2008) predicted that global climate change 

could bring an influx of climate refugees to the Pacific Northwest. While it is difficult to estimate the 

extent to which this would change projected population growth in the valley, the need for planners 

and policymakers to take migration trends into account is a recognized necessity (City of Portland 

and Multnomah County 2015, ODOT 2012). A review of climate change data and studies pertinent to 

the valley is provided in Appendix B. 

Connecting People with Nature 

National wildlife refuges in the Willamette Valley currently provide wildlife-orientated outdoor 

recreation and education opportunities to approximately 500,000 visitors a year (USFWS 2013a). 

Additionally, dozens of other federal, state, and local providers own or manage a wide range of 

nature-based recreation facilities (e.g., parks, trails, open spaces) across the Willamette Valley. The 

pressure on these facilities is expected to increase as the valley’s population increases. But not only is 

the valley’s population increasing, it is aging and becoming more ethnically diverse (OPRD 2008). 

These changes will place new pressures and demands on natural areas and the natural systems that 

support wildlife and wildlife related recreation. 

Nature-based recreation and education results in important economic benefits as well. The hundreds 

of thousands of valley residents spending dollars on nature-based recreation support local 

communities and aid in their economic development (Whelan et al. 2008, Carver and Caudill 2013). 

A recent study of the demographics and economic impacts of birding based on the 2011 National 

Survey of Fishing, Hunting, and Wildlife-Associated Recreation (USDI and USDC 2011) estimated 

that 892,000 Oregonians or about 23 percent of the state’s population participated in bird watching 

activities. On a national scale, 46.7 million birders spent about $41 billion on trips and equipment, 

creating 666,000 jobs and generating $31 billion in employment income and $13 billion in local, 

state, and federal tax revenue. An economic analysis of shellfish harvesting, hunting, fishing, and 

wildlife viewing across the state of Oregon prepared for ODFW and Travel Oregon (Dean Runyan 

Associates 2009), found that in 2008, hunting, fishing, and wildlife viewing resulted in expenditures 
Willamette Valley Conservation Study 

8 Strategic Habitat Conservation in Oregon’s Willamette Valley 

of about $128,000,000 in the Willamette Valley, which creates ancillary economic benefits as the 

dollars flow through local economies. 

The Crucial Role of Private Landowners 

The overwhelming majority of the valley’s remaining habitat, as well as needed restoration 

opportunities, occur on private lands. To date, the linchpin of much of the applied conservation 

efforts within the valley has been the cultivation and maintenance of relationships with private 

landowners by the valley’s agency and non-governmental organization (NGO) conservation 

practitioners. These relationships are based upon genuine collaboration and cooperation on the part 

of all parties involved. These principles are employed on both small and large conservation actions 

ranging from targeted invasive species management up to the acquisition of lands or easements from 

private landowners wanting to protect the conservation values on their properties in perpetuity. 

The implementation of these types of voluntary conservation partnerships has contributed in no small 

part to many successful outcomes for the conservation of the valley’s sensitive, native wildlife over 

the past decade and half. While there are myriad examples that could be highlighted which 

demonstrate how positive private/public collaborations are changing the face of conservation in the 

Willamette Valley, three examples represent current collaborative conservation efforts. 

A multi-year collaboration by numerous private landowners, public agencies, and non-governmental 

organizations (NGOs), led to a true Willamette Valley success story—the recovery and delisting of 

the Oregon chub—the first fish species to be delisted in the nation. Private landowners played a 

crucial role by restoring chub habitat on their lands, participating in the introduction of chub, and 

managing their lands to perpetuate chub populations in secure habitats. 

Another multi-year effort involving several dozen private landowners, public agencies, confederated 

tribes, and non-governmental organizations throughout Polk and Yamhill Counties are restoring and 

protecting Oregon white oak habitats in the northern part of the valley. These private landowners 

have enrolled their lands in various voluntary conservation partnerships that directly benefit listed 

species and migratory birds in decline. These partnership-driven collaborations cost effectively 

leverage limited public resources for the direct benefit of the valley’s native wildlife and plants while 

at the same time, supporting working lands and local economies. 

In the southern part of the valley along the lower Coyote Creek riparian corridor, federal agencies 

and non-governmental organizations have cultivated strong relationships with private landowners 

through voluntary, nonregulatory programs to restore and protect nearly 450 acres of unique oakdominated floodplain forest and remnant native prairie meadows. Combined with 530 acres of 

federally managed lands, these efforts are directly contributing to recovering Bradshaw's lomatium as 

well as benefiting many other sensitive species. 

These success stories highlight the crucial role of private landowners and public/private cooperative 

efforts in protecting and restoring the valley’s native habitats. These efforts not only benefit wildlife 

and their habitats, but the diverse local communities (and associated economies) enmeshed within 

this landscape, through large and small restoration efforts aimed at recovering listed species, 

conserving migratory bird populations, and connecting people with nature. This partnership approach 

is the fabric of conservation delivery in the valley and future conservation success will continue to be 

based on cooperative public/private partnerships. 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 9 

Strategic Habitat Conservation 

The USFWS adopted SHC as its approach for the efficient conservation 

of wildlife populations with the overall goal of maintaining functional 

landscapes capable of supporting self-sustaining populations of native 

fish, wildlife, and plants (USFWS 2008a). Functional landscapes are 

lands and waters with the properties and elements required to support 

desirable populations of fish and wildlife, while also providing human 

society with desired goods and services, including food, fiber, water, 

energy, and living space (USFWS 2012). 

SHC is an iterative process of developing and refining a conservation 

strategy, making efficient management decisions, and using research and monitoring to assess 

accomplishments and inform future iterations. The SHC process is a cycle involving biological 

planning, conservation design, conservation delivery, and outcome-based monitoring (USFWS 

2008a). This study sets the stage for efficient conservation delivery by completing the first two 

phases of SHC—Biological Planning and Conservation Design. 

As per SHC protocols, we worked with ODFW and other governmental and non-governmental 

organizations engaged in conservation efforts in the Willamette Valley to select a suite of species to 

represent the valley’s native terrestrial habitats of concern, established population objectives for 

those species, and determined a spatial distribution of habitat needed to achieve the population 

objectives. Then, we used the conservation network design optimization algorithm Marxan (Ball and 

Possingham 2000) to identify priority areas of the valley within which the habitat objectives could be 

achieved. Each step is descried below with greater detail provided in Appendices D, E, and F. A list 

of governmental and non-governmental organizations we worked with is provided in Appendix K. 

Biological Planning 

Biological Planning involves goal setting, selecting species as conservation targets, and establishing 

quantifiable population objectives for the selected species. 

Selecting Conservation Targets 

Because it is impractical to develop conservation prescriptions for all species present in a study area 

as large as the Willamette Valley, we selected a subset of species to represent the valley’s native 

habitats. This was done under the assumption that by implementing management strategies that 

support the ecological conditions favored by the targets, the conditions for a larger set of species 

characteristic of that habitat would also be supported (USFWS 2012). 

As with the Strategic Conservation Management in Oregon’s Willamette Valley (USFWS 2014), we 

used as the basis for selecting species, the valley’s strategy habitats described in the Oregon 

Conservation Strategy (ODFW 2006). Those habitats are grasslands (including oak savanna), oak 

woodlands, riparian, and wetlands (including all freshwater wetlands and wet prairie). The WVCS 

used those habitats, but divided them slightly differently based on available GIS vegetation data 

layers that allowed us to take a finer look. We separated oak savanna from grasslands and divided 

riparian habitats into forest and shrubland constituent parts and selected species to represent those 
Willamette Valley Conservation Study 

10 Strategic Habitat Conservation in Oregon’s Willamette Valley 

parts. Wetlands were represented within wet prairies and riparian areas. Descriptions of these priority 

habitat types are in Appendix C. 

We convened a group of wildlife biologists with expertise in the valley to score and rank a list of 

species that could potentially represent the habitat types against a set of ecological and management 

criteria that assessed a species’ ability to represent the larger suite of species dependent on the same 

habitat types. A detailed description of the species selection process is provided in Appendix D. The 

list of the species selected to represent habitats (conservation targets) is in Table 2. 

Table 2: Conservation Targets 

Species Habitat 

Western meadowlark 

Oregon vesper sparrow Prairie (upland and wet) 

Western bluebird Oak savanna 

Slender-billed white-breasted nuthatch Oak woodland 

Yellow warbler Riparian hardwood forest 

Yellow-breasted chat Riparian shrublands 

Western Meadowlark 

Western meadowlark (Sturnella neglecta), the State Bird of Oregon, was selected to represent 

grassland habitats of the Willamette Valley Upland Prairie and Savanna and Willamette Valley Wet 

Prairie systems (NatureServe 2011; see Appendix C) and the species dependent upon those habitats. 

They are ground-nesting, grassland obligates that are far more likely to nest in large blocks of habitat 

(>300 acres) than smaller grassland fragments (Altman 1999). ODFW recommends maintaining 

large expanses of grassland and minimizing disturbance during the breeding season (April 15-July 

15) as an important conservation action for western meadowlarks in the valley (ODFW 21016). 

Western meadowlark were once described as “probably the most widely distributed and among the 

most abundant of the permanent resident birds” (Gabrielson and Jewett 1940), but recent surveys of 

grassland birds in the Willamette Valley documented that over a 12-year time frame (1996-2008) 

western meadowlark suffered a 60 percent decrease in relative abundance (the mean number of 

individuals tallied at each sample station) and a 30 percent decrease in the number of areas in which 

meadowlarks were detected (ODFW 2010). These results are reflected by the Breeding Bird Survey 

which documented a 10 percent decline per year from 1966 to 2007, the last year data are available 

for the valley (Sauer et al. 2008). This 10 percent decline per year equates to an overall population 

loss of about 98 percent since the mid-1960s. ODFW now considers the once common State Bird of 

Oregon as threatened with extirpation from the valley (ODFW 2008). 

Oregon Vesper Sparrow 

The Oregon vesper sparrow (Pooecetes gramineus affinins), another ground-nesting, grasslanddependent species, is one of four subspecies of vesper sparrow (Jones and Cornely 2002). It is 

endemic to the Willamette Valley. In the 1930s, it was described as an “abundant summer resident in 

the Willamette Valley” (Gabrielson and Jewett 1940), but now has “nearly vanished from western 

Oregon” (Csuti et al. 2001). Breeding Bird Surveys indicate they have declined about 8.6 percent per 

year since the mid-1960s or by about 97 percent overall (Sauer et al. 2008). ODFW considers Oregon 

vesper sparrow as being imperiled with extirpation from the valley (ODFW 2008), and recommends 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 11 

maintaining grassland habitats and reducing or avoiding mechanical operations during their nesting 

season from mid-May to mid-July as important conservation actions for the Oregon vesper sparrow 

(ODFW 2016). 

Western Bluebird 

The Western bluebird (Sialia mexicana) was selected to represent the oak savanna component of the 

Willamette Valley Upland Prairie and Savanna system (NatureServe 2011; see Appendix C). In the 

1930s, western bluebirds were so common in western Oregon that “it vies with the robin for first 

rank as a dooryard bird” (Gabrielson and Jewett 1940). These cavity-nesting birds have since 

suffered precipitous population declines due to habitat loss and degradation, and avian competition 

for nesting cavities from species such as the non-native European starling (Marshell et al. 2003). 

Recent range contractions and extirpations have been documented in mainland British Columbia, 

Vancouver Island, the San Juan Islands, north Puget lowlands, and the Long Beach Peninsula (Rich 

et al. 2004, Guinan et al. 2008, Altman 2011), although they have recently been reintroduced in the 

San Juan Islands. Western bluebirds in the Willamette Valley are now separated from the rest of the 

species range (Keyser et al. 2004). ODFW recommends maintaining or restoring grassland and oak 

savanna habitat with both snags and live trees with large, dead branches to improve availability of 

nest cavities as important conservation actions for the western bluebird (ODFW 2016). 

Slender‐billed White‐breasted Nuthatch 

The slender‐billed white‐breasted nuthatch (Sitta carolinenses aculeate) was selected to represent 

North Pacific Oak Woodlands (NatureServe 2011; see Appendix C) and species dependent on that 

habitat. It is a small, cavity-nesting, passerine closely associated with Oregon white oak woodlands 

of the Willamette Valley (Hagar 2003). Described in the 1930s as being a “regular resident of the 

Willamette Valley” and “a common bird throughout most of its territory” (Gabrielson and Jewett 

1940), they have also experienced both range contractions and population declines with extirpations 

documented in western Washington (Grubb and Pravosudov 2008, Rich et al. 2004). ODFW 

recommends maintaining large oaks containing cavities and implementing controlled burns where 

possible to maintain oak tree dominance and prevent conifer encroachment as an important 

conservation action for the slender‐billed white‐breasted nuthatch (ODFW 2016). 

Yellow Warbler 

Yellow warbler (Setophaga petechia) was selected to represent riparian hardwood forests of the 

North Pacific Lowland Riparian Forest and Shrubland system (NatureServe 2011; see Appendix C) 

and the other species dependent upon that habitat. They breed most commonly in riparian, deciduous 

thickets including cottonwood gallery forests (Lowther et al. 1999). They were once the most 

conspicuous breeding warbler in Oregon, but declined precipitously before the advent of the 

Breeding Bird Survey (BBS) (Gabrielson and Jewett 1940, cited in Marshall et al. 2003). Since the 

mid-1960s, the population declines have been attributed to the loss of riparian habitat and cowbird 

parasitism (Marshall et al. 2003, Rich et al. 2004). 

Yellow-breasted Chat 

Yellow-breasted chat (Icteria virens) were selected to represent riparian shrublands of the North 

Pacific Lowland Riparian Forest and Shrubland system (NatureServe 2011; see Appendix C) and the 
Willamette Valley Conservation Study 

12 Strategic Habitat Conservation in Oregon’s Willamette Valley 

other species dependent on that habitat such as the willow flycatcher, another bird of regional 

conservation concern (USFWS 2008). In the 1930s, yellow-breasted chat were a “common summer 

resident and breeding species in tangled thickets of stream bottoms throughout the state, except 

coastal counties” and “a common species in Jackson and Josephine Counties in the upper Rogue, 

along the Umpqua in the vicinity of Roseburg, and throughout the Willamette Valley” (Gabrielson 

and Jewett 1940). But that is far from the current condition, as ODFW now considers yellowbreasted chat as being threatened with extirpation from the valley (ODFW 2008). The BBS 

documents a population decline of 3.2 percent per year from 1966 to 2007 (Sauer et al. 2008), 

equating to a loss of 76 percent of the 1960s population. ODFW recommends restoring large, dense 

thickets of native-shrub dominated riparian areas as an important conservation action for yellowbreasted chat (ODFW 2016). 

Other Species of Conservation Concern 

While the list of species the biologists scored included bird, mammal, amphibian, fish, and plant 

species, only bird species were selected. Birds have long been used as surrogates of air quality (e.g., 

the canary in the coal mine) and are often used as surrogates for biodiversity because they are well 

known and studied, their population trends can correlate with those of other taxa (Gregory et al. 

2008), and monitoring their responses to management actions provides a measure of the effectiveness 

of the action (Stephens et al. 2011). 

Identifying networks of priority conservation areas on the basis of birds alone has been found to 

perform well in representing overall species diversity, but the overall effectiveness of the network 

design can be improved by adding other taxa, especially range-restricted taxa (Larsen et al. 2012). 

We did that by including other species of conservation concern that require special management 

needs that would not necessarily be met through a network design based solely on the selected bird 

species. These species face unique threats, limited range, legal mandates, or other special 

circumstances. The list of other species of conservation concern is in Table 3, and descriptions of the 

species are available in Appendix E. 

Table 3: Other Species of Conservation Concern 

Birds Plants 

Streaked horned lark Bradshaw’s lomatium 

Invertebrates Golden paintbrush 

Fender’s blue butterfly Kincaid’s lupine 

Taylor’s checkerspot butterfly Nelson’s checker-mallow 

Willamette valley daisy 

Establishing Biological Objectives 

Biological objectives represent a measurable expression of a desired outcome and serve as one of the 

basis for estimating how much habitat is needed to be maintained based on the current state of 

knowledge related to habitat suitability, territory size, population viability, and probability of 

occurrence in suitable habitat (USFWS 2008a). 

More than 15 years ago, Altman (1999) proposed a landbird conservation strategy of protecting, 

restoring, and managing suitable habitat in proximity to existing populations, providing habitat for 

the populations to grow and for dispersers to establish new subpopulations on newly restored habitat 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 13 

(Altman 1999, ODFW 2010). This strategy, focusing initial efforts near remaining populations and 

radiating out from them influenced the development of this study. 

SHC is an objectives-based planning protocol, requiring us to develop quantifiable objectives for the 

selected species. We chose to develop population objectives and convened panels of researchers and 

biologists with expertise in each of our conversation target species and asked them what would 

reasonable population objectives be, that when realized, would indicate that the species were well on 

the road to recovery. 

Our conservation targets fell into two broad categories: those that are rare and imperiled, with very 

small and fragmented populations that have suffered steep, long-term declines (the grassland, oak 

savanna, and riparian shrubland species) and those with somewhat larger, though still relatively small 

populations, and less certain population trends (the oak woodland and riparian forest species). 

For the rare and imperiled species (western meadowlark, Oregon vesper sparrow, western bluebird, 

and yellow-breasted chat), our expert panel suggested a long-term population goal of 6,000, which 

when met, would convey a high probability for long-term persistence (Traill et al. 2007, Reed et al. 

2003). For the species with somewhat larger populations (slender-billed white-breasted nuthatch and 

yellow warbler), the panel agreed that a long-term, aspirational goal that increased the population by 

50 percent over 50 years would indicate they were recovering and would be consistent with the goals 

of the North American Landbird Conservation Plan (Rich 2004). 

We stepped-down the long-term aspirational goals to shorter-term population objectives, which we 

used to determine habitat objectives. To do that, we calculated the annual growth rate needed for 

each species, to meet the long-term goals over a 50-year time frame and then applied that rate to the 

current population estimate for 10 years. Current population estimates, goals, and objectives are 

provided in Table 4. A detailed description of how we set population objectives is provided in 

Appendix E. 

Table 4. Population Estimates and Objectives 

Conservation Targets Current Population 

Estimate* 

Short-term 

Population Objective 

Long-term 

Population Goal 

Western meadowlark 1,200 1,656 6,000 

Oregon vesper sparrow 550 887 6,000 

Western bluebird 2,000 2,490 6,000 

Slender-billed whitebreasted nuthatch 12,100 13,447 18,150 

Yellow warbler 12,400 13,122 18,600 

Yellow-breasted chat 900 1,315 6,000 

* Population estimate is specific to the Willamette Valley. See Appendix E for a discussion on how they 

were developed. 

Establishing Habitat Objectives 

Habitat objectives describe the area and distribution of habitat across a landscape thought to be 

necessary to achieve population objectives (NEAT 2006). Appendix E provides greater detail about 

how we developed the habitat objectives. 
Willamette Valley Conservation Study 

14 Strategic Habitat Conservation in Oregon’s Willamette Valley 

Terrestrial Habitats 

Successful conservation strategies address the factors limiting population growth. For grassland 

birds, ODFW (2006, 2016) identified the loss and degradation of grassland habitats, nest predation, 

and nesting failure due to the timing of land management practices occurring during critical nesting 

times (mid-April to mid-July). The extensive loss of native grasslands has resulted in small and 

disjunct populations (i.e., disjoined and distinct from one another) that are at increased risk of 

extirpation, genetic isolation, and barriers to dispersal especially for some amphibians, reptiles, and 

small mammals. Small patches of habitat cannot satisfy the space requirements for some birds (e.g., 

western meadowlark), reptiles, and medium to large mammals (Altman et al., 2001). For the riparian 

birds the loss of large habitat patches and altered disturbance regimes that create suitable habitat 

conditions are limiting populations (ODFW 2006, 2016). For the cavity-nesting oak species, it is 

habitat loss along with fewer mature oaks with cavities and competition from nonnative species for 

those cavities (ODFW 2006, 2016). 

The expert panels summarized these factors as an insufficient number, size, and distribution of 

suitable habitat with long-term commitments to maintain breeding and rearing habitats to ensure 

long-term persistence. To address this factor, for each species we developed objectives for the 

number, size, and distribution of a network of core habitat patches—areas of suitable habitat and of 

sufficient size which contain the properties and elements required for successful reproduction and 

survival of the targeted species. Within these core habitat patches, wildlife management would be 

prioritized over other management concerns. 

To determine the amount of habitat needed for each network of core habitats, we used the largest and 

densest known subpopulations of each species in the valley as the reference from which to establish 

area requirements. These typically occurred on large, single ownership parcels with generally high 

quality habitat. As most of the landscape outside these ownerships is fragmented and of lower quality 

we assumed that 50 percent more area would be required compared to the reference to support an 

equal number of breeding pairs. The fact that territory size varies with habitat quality is well 

established and has been demonstrated empirically in the valley for grassland birds (Altman 1999, 

Altman et al. 2011). For species without reference subpopulations we used breeding territory sizes 

reported in the literature, and increased that size by 50 percent for the reasons given above. We took 

these acreage amounts and split them into the number, size, and distribution of core habitat patches 

(the network) needed to support each population objective. 

The Wetlands Conservancy mapped wetlands of conservation significance for the Western 

Governors Association’s Crucial Habitat Assessment Tool or CHAT (WGWC 2013). Where the top 

50 percent highest ranking wetlands intersected mapped grassland or riparian areas in our GIS 

landcover database, they became targets for conservation. Wet prairie habitat is included in the 

grasslands habitats. 

Aquatic Habitats 

While instream aquatic habitats were not a specific WVCS target, there have been many recent 

studies and modeling efforts that identified areas of conservation significance along the valley’s 

rivers and streams. These include anchor habitats—areas with opportunities to reconnect the river to 

its historic floodplain with limited social impact that were mapped as part of the Willamette Planning 

Atlas (Hulse et al. 2002) and by the Oregon Watershed Enhancement Board (OWEB 2014); instream 

cold water refugia (cold points) as mapped by Hulse et al. (2007); and Zone of Influence—locations 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 15 

of revetments that if removed would provide a high degree of fish habitat restoration with limited 

social impacts that were mapped as part of a U.S. Army Corps of Engineers’ study (Hulse et al. 

2013). We overlaid these mapped area of conservation significance in our GIS database with our 

targeted habitat types, and where they intersected, they became additional conservation targets. 

Habitat Objectives 

The following set of tables provides for each species/habitat combination the recommended number 

of core habitats patches, total acreage of those patches, and how they should be distributed across the 

valley. In establishing these habitat objectives, we assumed that providing a secure habitat base 

capable of supporting 50 percent of each species’ population objective would be sufficient to begin to 

recover the depressed populations, with the remainder of each species’ population objective 

occurring outside of the secure habitat base. This assumption must be tested through assumptionbased research and the objectives modified based on the results of that research. 

To distribute the core habitat patches, we split the valley into three regions along a north-south 

gradient (north is north Salem, central is from Salem to Corvallis, and south is south of Corvallis) 

and stratified the habitat objective across the three zones. To further ensure an appropriate 

distribution of these core habitat patches, recommendations are given for which Level IV Ecosystem 

(Omernick 1987) the patches should occur. A detailed discussion of these objectives and the 

assumptions used to calculate them is provided in Appendix E. 

Table 5: Grassland Core Habitat Distribution (Western Meadowlark) 

Area Number of Core Habitat Patches Total Acreage of Core Habitat Patches 

Large Medium Small Total Large Medium Small Total 

North 0 1 2 3 0 938 1,125 2,063 

Central 1 2 4 7 1,313 1,875 2,250 5,438 

South 1 2 6 9 1,313 1,875 3,375 6,563 

Total 2 5 12 19 2,625 4,688 6,750 14,063 

Since the strategy is to begin work in proximity to existing population centers, the network is located 

mostly in the southern and central parts of the valley reflecting the current and likely historic 

distribution of western meadowlark in the valley. The vast majority of the network should occur in 

the three valley lowland Level IV ecoregions. 

Table 6: Grassland Core Habitat Distribution (Oregon Vesper Sparrow) 

Area Number of Core Habitat Patches Total Acreage of Core Habitat Patches 

Large Medium Small Total Large Medium Small Total 

North 0 1 2 3 0 341 409 750 

Central 1 2 3 6 477 682 614 1,773 

South 2 4 6 12 955 1,364 1,227 3,454 

Total 3 7 11 21 1,432 2,386 2,250 6,068 

This distribution of the network, focused in the southern and central parts of the valley, reflects the 

current distribution of Oregon vesper sparrow. Because Oregon vesper sparrow occur more often in 

the valley foothills rather than the valley floor as western meadowlark do, at least 80 percent of the 

network should be located in the Valley Foothills Omernik Level IV ecoregion (Omernik 1987). 
Willamette Valley Conservation Study 

16 Strategic Habitat Conservation in Oregon’s Willamette Valley 

Table 7: Oak Savanna Core Habitat Distribution (Western Bluebird) 

Area Number of Core Habitat Patches Total Acreage of Core Habitat Patches 

Large Medium Small Total Large Medium Small Total 

North 1 3 6 10 263 563 675 1,500 

Central 2 3 6 11 525 563 675 1,763 

South 1 3 5 9 263 563 563 1,388 

Total 4 9 17 30 1,050 1,688 1,913 4,650 

Reflecting western bluebird distribution in the valley, at least two habitat patches should be located 

in each of the four Omernik Level IV Ecoregions (Omernik 1987), with the majority located in the 

Prairie Terraces and Valley Foothills Level IV ecoregions. 

Table 8: Oak Woodland Core Habitat Distribution (Slender-billed White-breasted Nuthatch) 

Area Number of Core Habitat Patches Total Acreage of Core Habitat Patches 

Large Medium Small Total Large Medium Small Total 

North 5 10 20 35 4,500 6,000 6,000 16,500 

Central 5 10 20 35 4,500 6,000 6,000 16,500 

South 5 10 19 34 4,500 6,000 5,700 16,200 

Total 15 30 59 104 13,500 18,000 17,700 49,200 

To reflect the current and likely historic distribution of nuthatches in the valley, at least six habitat 

patches should be located in each of the four Omernik Level IV Ecoregions (Omernik 1987), with the 

majority located in the Valley Terraces and Valley Foothills Level IV Ecoregions. 

Table 9: Riparian Forest Core Habitat Distribution (Yellow Warbler) 

Area Number of Core Habitat Patches Total Acreage of Core Habitat Patches 

Large Medium Small Total Large Medium Small Total 

North 3 5 11 19 1,620 1,800 1,980 5,400 

Central 2 5 11 18 1,080 1,800 1,980 4,860 

South 2 5 11 18 1,080 1,800 1,980 4,860 

Total 7 15 33 55 3,780 5,400 5,940 15,120 

Reflecting the current and likely historic distribution of yellow warblers in the valley, at least two 

habitat patches should be located in each of the four Level IV Ecoregions, but the vast majority 

should occur in the Willamette River and Tributaries Gallery Forest Level IV ecoregion. 

Table 10: Riparian Shrubland Core Habitat Distribution (Yellow-breasted Chat) 

Area Number of Core Habitat Patches Total Acreage of Core Habitat Patches 

Large Medium Small Total Large Medium Small Total 

North 1 2 4 7 450 600 600 1,650 

Central 1 3 3 7 450 900 450 1,800 

South 1 2 3 6 450 600 450 1,500 

Total 3 7 10 20 1,350 2,100 1,500 4,950 

Similar to yellow warbler habitat, at least two subpopulations should be located in each of the four 

Level IV Ecoregions, but the vast majority should occur in the Willamette River and Tributaries 

Gallery Forest Level IV ecoregion. 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 17 

Other Species of Conservation Concern 

Other species of conservation concern require site-specific actions to ensure their conservation. The 

expert panels recommended conserving specific extant populations of the listed species as the best 

way to assist in achieving recovery criteria (USFWS 2010a). The areas supporting those populations 

are included in the final portfolio of important areas for land-based conservation actions. Once a 

recovery plan is adopted for the streaked horned lark, population and habitat objectives from that 

plan would be adopted and added to this study. Additional detail regarding biological and habitat 

objectives for the other species of conservation concern is provided in Appendix E. 

Conservation Design 

The Service traditionally approached conservation with an emphasis on more, more protection, more 

restoration, and more management. Recent advances in the field of conservation biology, however, 

are leading the Service in a new direction—a strategic pursuit of sustainable landscapes. Advances in 

the fields of conservation planning and design, and landscape and population ecology have replaced 

the emphasis on “more” to the science of “how much more” and “where” as we consider how best to 

pursue our mission (NEAT 2006). Conservation Design, element two of the SHC cycle, is predicated 

on the belief that the potential to affect wildlife populations varies over space in response to site 

characteristics and landscape context. If it does not, it matters little where habitat is conserved 

(USFWS 2008a). Conservation design provides the roadmap for element three of the SHC cycle: 

conservation delivery. 

Identifying Priority Areas for Conservation 

Prioritizing areas of the Willamette Valley for conservation entails an evaluation of the relative value 

of one area against another area’s ability to meet multiple conservation objectives for species and 

habitats distributed across hundreds of thousands of acres throughout the 5,000 square-mile 

Willamette Valley ecoregion. This complexity precludes simple mapping exercises to arrive at an 

efficient conservation design. To deal with this complexity, we used the conservation network design 

optimization algorithm, Marxan (Ball et al. 2009). Marxan (and its predecessors SPEXAN and 

SITES) has been used for terrestrial and marine conservation assessments around the world (Beck 

and Odaya 2001, Andelman and Willig 2002, Noss et al. 2002, Leslie et al. 2003, Carroll et al. 2003, 

Floberg et al. 2004, USFWS 2013b, Arid Lands Initiative 2014). A detailed description of Marxan 

and how it was used is provided in Appendix F. 

Because we wanted to prioritize areas where the targeted species occur (i.e., the disjunct populations 

ODFW (2006) describes), we compiled recent bird observation data (from 2008 to 2013) from 

numerous sources. These included survey data gathered by the American Bird Conservancy, the 

Portland Bureau of Environmental Services, the Portland Chapter of The Audubon Society, the 

Oregon Department of Fish and Wildlife, and The Oregon Chapter of The Nature Conservancy. We 

also used data from a 2013 vesper sparrow survey (Altman 2013), Breeding Bird Survey data, and 

vetted eBird observations. 

The Maxan analysis identified 76 areas, within which there are recent documented occurrences of the 

target species and sufficient habitat to create and maintain core habitat patches that would contribute 

to a network or an extant population of a listed species whose protection would aid in recovering that 

species. We are calling these areas “Priority Conservation Areas” (PCAs) (Figure 1). The PCAs are 
Willamette Valley Conservation Study 

18 Strategic Habitat Conservation in Oregon’s Willamette Valley 

embedded within and a subset of the Conservation Opportunity Areas identified by ODFW (2016), 

which are areas known for their importance for fish and wildlife conservation. 

It is important to note that because the minimum amount of land that Marxan either adds to or 

excludes from the network design is 250-acres (the Marxan model used 250-acre hexagon assessment 

units), land cover types such as roads and other areas that are unsuitable for wildlife habitat are 

included in each PCA. Only about 30 percent of the area included in all of the PCAs contains the 

habitats of concern. Acreage of the various targeted habitat types and the number of PCAs within 

which they occur is provided in Table 11. 

Table 11. Habitat types and acreage within the PCAs. 

Habitat type Acreage PCAs Habitat type Acreage PCAs 

Grasslands 27,907 27 Wetlands of conservation 

concern 

11,491 52 

Oak savanna 4,848 27 Anchor habitats 6,471 11 

Oak woodlands 49,800 52 Cold points 1,091 9 

Riparian forest 27,915 75 Zones of influence 5,113 19 

Riparian shrubland 7,283 58 

Wilderness Review 

A GIS analysis of the study area was conducted to determine the potential for new wilderness areas. 

The analysis attempted to find any roadless area of 5,000 acres or greater within the valley, or any 

roadless areas within the valley that extend beyond the ecoregional boundary that equaled at least 

5,000 acres. No such areas were identified. 

The 5,786-acre Table Rock Wilderness occurs to the east of the study area about 19 miles southeast 

of Molalla. Table Rock Wilderness was designated by the United States Congress in 1984 and is 

managed by the Bureau of Land Management (BLM). 

GAP Analysis 

With PCAs identified, the next step is to determine to what extent each network already occurs on 

protected lands, such as the grasslands at W.L. Finley National Wildlife Refuge, riparian habitats at 

ODFW’s E.E. Wilson Wildlife Area, and Metro’s Smith and Bybee Wetlands. We used data from the 

Protected Area Database of the United States (PAD-US), which includes a “gap status” of protected 

lands. The gap status indicates how the lands are being managed for conservation purposes. A gap 

analysis typically only considers lands in gap status 1 and 2, which have permanent protection from 

conversion and a mandated management plan to maintain a primarily natural state, but may be 

subject to practices that suppress natural disturbances such as wildfire. We used gap status 1 and 2 

lands in this analysis, but also included some areas that were not gap status 1 or 2, but are public 

lands that contain quality habitat, have recent documented occurrences of the targeted species, are of 

sufficient size, and are governed by management plans that protect wildlife values. 

The following series of tables (Tables 12-16) provides a graphical representation of where in the 

valley network objectives are achieved, where they have been partially achieved, and where no 

protected areas are of sufficient size suitable for the network. The number in the “Objective” column 

is the habitat objective (i.e., the number core habitat patches). The number in the “Achieved” column 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 19 

 

Figure 1. Priority Conservation Area Map 
Willamette Valley Conservation Study 

20 Strategic Habitat Conservation in Oregon’s Willamette Valley 

This document continues on the next page. 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 21 

represents the number of protected areas with suitable habitat and sufficient size to be considered a 

core patch. The colors differ based on whether the objective has been achieved (green), partially 

achieved (orange), or no objectives have yet been achieved (purple). 

 = Objectives achieved 

 = Objectives partially achieved 

 = No objectives achieved 

Table 12: Grasslands (Western Meadowlark and Oregon Vesper Sparrow) 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North N/A N/A 1 1 2 0 

Central 1 1 2 0 4 0 

South 1 1 2 0 6 0 

Table 13: Oak Savanna (Western Bluebird) 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 1 0 3 0 6 0 

Central 2 0 3 0 6 1 

South 1 0 3 0 5 1 

Table 14: Oak Woodlands (Slender-billed White-breasted Nuthatch) 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 5 1 10 1 20 1 

Central 5 0 10 0 20 1 

South 5 0 10 1 19 1 

Table 15: Riparian Forests (Yellow Warbler) 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 3 1* 5 0 11 2 

Central 2 1 5 0 11 0 

South 2 1 5 1 11 3 

* Sandy River Delta (not GAP Status 1 or 2) 

Table 16: Riparian Shrublands (Yellow-breasted Chat) 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 1 1** 2 0 4 1 

Central 1 0 3 0 4 0 

South 1 0 2 0 3 1 

** Smith and Bybee Wetlands (not GAP Status 1 or 2) 

Overall, while portions of the networks are in place, lands protected to date within the PCAs are 

mostly of insufficient size to meet the objectives for even a small core habitat patch. They do 
Willamette Valley Conservation Study 

22 Strategic Habitat Conservation in Oregon’s Willamette Valley 

however create a land base from which to build upon to create bigger blocks of habitat. A detailed 

discussion of the gap analysis is provided in Appendix H. 

It is interesting to note that the three National Wildlife Refuges with the most grassland habitat (W. 

L. Finley, Ankeny, and Baskett Slough) support healthy populations of western meadowlark, and 

have so for years. Yet populations of western meadowlark and other grassland birds have declined 

precipitously around them (Altman 1999, ODFW 2010). This highlights the important point that a 

few widely-spaced “islands” of habitat set aside for wildlife, even though relatively large, do not 

provide a habitat configuration in terms of amount, distribution, and quality sufficient to maintain, let 

alone restore the depressed populations of grassland-dependent species across the valley. 

Threats Analysis 

Understanding potential threats that might render areas of a PCA unusable for conservation is a 

critical step in developing appropriate conservation strategies (Surasinghe et al. 2012; Groves 2003). 

A wide variety of agents can threaten the integrity of a PCA, but due to the historic loss and 

conversion of native habitats and the anticipated surge in population growth, anthropogenic land use 

changes will likely present a greater challenge to restoring and maintaining biodiversity in the valley 

than climate change over the course of this century (Wilson et al. 2014). Climate change may 

actually benefit oak and prairie systems of the valley (Bachelet et al. 2011). Because of that, we 

focused on the potential for future development as the greatest threat to PCAs. 

We used the Development 2050 scenario from the Willamette River Basin Planning Atlas as it 

reflects a loosening of land use policies that allows market forces freer rein across the valley’s 

landscape, creating an aggressive development scenario that was judged by project stakeholders to 

still be within the range of future development considered plausible (Hulse et al. 2002). This scenario 

mapped areas likely to be converted under loosened land use policies. 

We also looked at the projected change in each PCA that would be impacted by exurban 

development, using data from Theobald (2005). Future patterns of exurban growth were based on 

historical and current housing density patterns which were used to forecast future housing density 

projections (Theobald 2005). 

Both studies, neither of which include the potential impacts related to an influx of climate refugees, 

tend to indicate that PCAs, which are almost entirely outside current urban growth boundaries, would 

not be significantly impacted by future development. Not surprisingly, PCAs modeled to be most 

affected by future growth tend to be close to urban centers (Portland, Eugene, Corvallis). However, 

two of those PCAs currently house National Wildlife Refuges with private inholdings, and another 

supports a population of a listed plant species. That these PCAs are among the most threatened only 

highlights the need for immediate actions to conserve these valuable places for wildlife. Appendix I 

provides a detailed description of the Threats Analysis. 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 23 

Discussion 

The WVCS proposes a strategy for protecting and recovering depressed populations of the valley’s 

sensitive native wildlife through the establishment of networks of grassland, oak woodland, and 

riparian core habitats to be managed primarily for their wildlife values. Concentrating land-based 

conservation actions within select areas of the valley provides an opportunity to reestablish core 

habitat areas with enough room and the proper management needed to facilitate population growth 

and recovery. This would address two of the main factors ODFW (2006, 2016) cites as limiting the 

populations of sensitive native wildlife in the valley: (1) habitat loss and fragmentation leading to 

small, disjunct populations, which are at increased risk of extirpation and (2) management conflicts 

during critical nesting seasons for migratory birds. Concentrating land protection actions in select 

areas potentially addresses both issues. 

The select areas–the PCAs–are almost entirely a subset of Conservation Opportunity Areas (COAs) 

identified by ODFW (2016). ODFW identified COAs because “focusing investments on priority 

landscapes can increase likelihood of long-term success over larger areas, improve funding 

efficiency, and promoting cooperative efforts across ownership boundaries. Conservation 

Opportunity Areas are landscapes where broad fish and wildlife conservation goals could best be 

met. Working in these landscapes can increase the effectiveness of conservation actions at larger 

scales than can individual projects scattered about the state” (ODFW 2006). As the PCAs are 

embedded within ODFW COAs, the COAs delineate potential corridors for terrestrial wildlife 

movement. The Oregon Conservation Strategy (ODFW 2006) identifies many tools and actions 

individual landowners can use to maintain or enhance wildlife permeability on their properties. 

The PCAs were selected based on the habitat types present and because there are recent documented 

occurrences of the targeted wildlife species within them, many likely representatives of the small and 

disjunct populations ODFW (2006) describes. With suitable habitat of sufficient size, distribution, 

and appropriate management, over time, these small and disjunct populations can grow into larger, 

connected, and more secure populations. These larger populations can then become sources of 

individuals to shore up other small and disjunct populations or to establish new populations in nearby 

but generally unoccupied suitable habitat. Concentrating land protection actions in select areas 

provides the vehicle to achieve this end as the amount of land thought necessary to recreate core 

grassland, oak woodland, and riparian habitats is not trivial and protection of individual smaller 

properties in close proximity to each other can contribute to the creation of larger core patches. 

Embedding networks of variable-sized conservation reserves within the matrix of other land uses can 

also act as a buffer to the effects of climate change by minimizing the distance among reserves to 

facilitate species migrations (Heller and Zavaleta 2009). Distributing reserves across the landscape 

also helps safeguard the targeted species against natural catastrophes that could eliminate them from 

reserves in close proximity to each other and helps conserve the genetic and ecological variation that 

occurs in species and plant communities across their range (Akҫakaya 2000, Bull et al 2007, Groves 

et al 2002, Lande 1993, Margules and Pressey 2000). 

This study provides a blueprint for restoring a landscape structure favorable for sensitive native 

species of the major habitat types of the valley, but does not address other habitat types such as 

coniferous forests, instream habitats, or other specialized and local habitats as described by ODFW 

(2006), all of which deserve conserving. Providing habitat for the WVCS targeted species outside of 

the PCAs, will of course also be necessary, as those species occur beyond the PCAs. Nevertheless, 
Willamette Valley Conservation Study 

24 Strategic Habitat Conservation in Oregon’s Willamette Valley 

we believe that working together whenever possible to concentrate land-based conservation actions 

in close proximity to each other inside the PCAs to create blocks of secure habitat that are distributed 

across the valley is an important component to the recovery of many of the valley’s declining native 

and sensitive species. 

The work being accomplished by The Nature Conservancy, Greenbelt Land Trust, and the Tualatin 

Basin Partners Work Group provides examples from among the many ongoing efforts in the valley of 

how this strategy is already being implemented. In cooperation with local landowners, The Nature 

Conservancy is working to create significant blocks of wildlife habitat and a connectivity corridor 

from the Yamhill Oaks COA/PCA to Baskett Slough NWR by concentrating its land protection 

efforts in a few key areas. 

By combining TNC’s efforts with existing NRCS Wetland Reserve Program easements, a significant 

grassland/oak core habitat patch is taking shape in the Willamina Oaks COA/PCA. Likewise, 

Greenbelt Land Trust’s efforts at adding to its Bald Hill Farm holding in the Corvallis Forest and 

Balds COA/PCA is resulting in a significant area of grasslands and oak woodlands that individual 

purchases could not create alone. Greenbelt Land Trust is not only providing significant wildlife 

benefits, but creating a nearby access point to nature enjoyed by the residents of Corvallis and the 

surrounding area. 

The Tualatin Basin Partners Work Group, currently comprised of Metro, Clean Water Services, The 

Intertwine, The Wetlands Conservancy, Columbia Land Trust, and the Service, is focusing 

conservation efforts along the Tualatin River in an area characterized by relatively small lots. 

Protection of individual lots in close proximity to each other is resulting in wildlife benefits far 

greater than the individual pieces could provide alone. Metro is working to secure a wildlife corridor 

linking Chehalam Ridge to the Wapato Lake NWR. The Work Group is working toward a watershed 

with clean rivers and streams, robust natural areas, healthy and abundant fish and wildlife 

populations, and an opportunity for the 2.2 million residents of the Portland-Vancouver-Hillsboro 

metropolitan area to enjoy and connect to nature. These are a few examples of many conservation 

organizations which represent many ongoing efforts in the valley that demonstrate how focusing 

land-based conservation actions in select areas can result in benefits far greater than the sum of the 

parts. 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 25 

Recommendations 

1. Complete the network engaging as many partners as possible. 

The partnership approach, long practiced in the valley, is by far and away the best path forward to 

build upon the lands presently conserved within the PCAs to complete the network. The Strategic 

Conservation Management in Oregon’s Willamette Valley (USFWS 2014) identified many partners 

that are or could be engaged in reversing the declines of native habitats and species. This includes 

other federal, state, and local governmental agencies; non-governmental organizations; and most 

importantly, local landowners. Continuing to build and ultimately completing the conservation 

network will require contributions from as many partners as possible. 

Maintaining close coordination with the Oregon Department of Fish and Wildlife will be critical to 

the long-term success at developing the network. As the State agency, whose mission is “to protect 

and enhance Oregon’s fish and wildlife for use and enjoyment by present and future generations,” it 

is essential that ODFW and the Service be committed to common goals and strategies for restoring 

the valley’s native wildlife and plants. 

The WVCS was largely based on achieving the goal of the Oregon Conservation Strategy which is 

“to maintain healthy fish and wildlife populations by maintaining and restoring functioning habitats, 

preventing the declines of at-risk species, and reversing declines in these resources where possible” 

(ODFW 2006). Implementing conservation strategies described in this study in lock-step with 

ODFW is the surest path to success. 

The Coalition of Oregon Land Trusts (COLT) is the only association of land trusts in Oregon. COLT 

focuses on improving and advancing land conservation in the state through increased land trust 

capacity and coverage, and engagement of stakeholders. With a core value of cooperative 

partnerships with private landowners, public agencies, and community leaders to achieve land trust 

goals, COLT and its member organizations is a vital partner in conservation delivery and their 

participation in developing the network is crucial to successful implementation. 

Emerging partnerships such as the Tualatin Basin Partners Work Group and the Pacific Birds Habitat 

Joint Venture Prairie-Oak Bird Initiative, to name but a few, should also be supported. As noted 

above, the Tualatin Basin Work Group is developing a coordinated strategy for long-term habitat 

protection, restoration, and public access along the Tualatin River. The Pacific Birds Habitat Joint 

Venture is launching a Prairie-Oak Bird Initiative that will address the long-term conservation of 

prairie-oak birds in the Cascadia ecoregion. The Service should be a key player in these and the many 

other conservation-based initiatives in the valley. 

2. Develop a plan to implement WVCS findings. 

The Service will use the results of the WVCS to develop a plan to implement aspects of the WVCS 

best suited for the Service to implement. The plan would include a range of implementation 

alternatives to be analyzed through a public planning process. The alternatives will present how and 

where the Service could compliment the work of its partners by identifying areas of the valley where 

the Service would work with interested landowners wishing to voluntarily collaborate on the 

conservation of Service Trust resources. The Service calls this process Land Protection or 

Conservation Planning - which can result in the delineation or description of areas approved for 

NWRS land protection (conservation) actions, such as acquisition, easements or agreements. It is the 
Willamette Valley Conservation Study 

26 Strategic Habitat Conservation in Oregon’s Willamette Valley 

long standing policy of the Service to only acquire real property interests on a willing seller basis. 

The Service will engage local communities and seek public comments on the alternatives. 

3. Evaluate lands for their nature-based recreational and educational opportunities. 

Expanding opportunities for nature-based recreational and educational opportunities is a goal of 

ODFW, The Intertwine, Rivers to Ridges, COLT, the Service, and many other conservation partners 

in the valley. Along with evaluating the wildlife values of each parcel offered for protection, an 

analysis of the site’s potential for providing public access to nature-based recreational and 

educational opportunities should be completed. Parcels that could provide such opportunities should 

be prioritized over a parcel with similar wildlife values, but without those opportunities. 

4. Incorporate WVCS results into other Service programs. 

The PCAs developed through the WVCS represent the Service’s highest priority areas of the valley 

within which to conduct land-based conservation actions for the benefit of the valley’s native wildlife 

and plants. The Service is creating a cross-programmatic Willamette Valley Landscape Conservation 

work plan that shows how (and helps us plan how) our combined activities connect to our 

conservation objectives for the valley. Through this effort, the Service should prioritize landowner 

assistance and funding opportunities to properties within the PCAs. These programs include the 

Partners for Fish and Wildlife, Wildlife and Sport Fish Restoration Program, Cooperative 

Endangered Species Conservation Fund grants (section 6 of the ESA), Habitat Conservation Planning 

Assistance, and on-going refuge management programs, among others. 

5. Continue to engage in local conservation planning and implementation efforts. 

Local conservation planning efforts are taking place across the Willamette Valley, through Counties, 

watershed councils, land trusts, and other NGOs. The Service has, and should continue to support 

these efforts. While each group has its own set of priorities and mandates, typically these efforts 

share a common goal of restoring and preserving wildlife habitat. The Service should continue its 

history of engagement in these planning efforts as it has recently done with other conservation 

partners in Yamhill County, the Lower Calapooia-Santiam, and the Lower North Santiam to look for 

common ground in each effort’s unique goals and objectives to see where there is overlap with the 

goals and objectives of the WVCS. Common ground leads to coordinated actions. 

6. Develop and facilitate a conservation communication network. 

Several organizations in the Willamette Valley provide communications related to wildlife 

conservation activities, such as restoration projects, volunteer opportunities, and wildlife-oriented 

recreation. Forming a “Community of Practice” and network related to conservation communications 

would contribute to creating and delivering more effective, visible, and clear conservation 

communications. This network could amplify conservation needs and public opportunities to get 

involved in programs that are of interest. The Service recommends that a Conservation 

Communication Network be created for conservation communicators in the valley that would 

collaborate to craft strategies and messages for both traditional media and evolving social media. 

7. Cooperatively develop Canada Goose management strategies. 

The Service will continue to engage with relevant parties such as ODFW, the Pacific Flyway 

Council, USDA Natural Resource Conservation Service, Pacific Birds Habitat Joint Venture, Oregon 

Farm Bureau, Oregon Association of Conservation Districts, Soil and Water Conservation Districts, 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 27 

private landowners, and others to identify and develop land management strategies to support and 

manage wintering geese and reduce goose depredation impacts to producers. The Service should also 

continue to coordinate with ODFW on Canada goose hunt program within the Northwest Permit 

Zone. 

8. Employ every tool in the Service’s conservation toolbox. 

Listed below are a variety of habitat conservation tools available to the Service that could be 

employed to meet the goals and objectives of this study. Should a land protection plan be adopted, it 

is the policy of the Service to acquire interests in land only from property owners wishing to work 

with the Service. Landowners within an approved acquisition boundary who do not wish to sell an 

interest in their property are under no obligation to do so. In all acquisitions, the Service is required 

by law to offer 100 percent of fair market value, as determined by an approved appraisal that meets 

professional standards and Federal requirements. 

Donations. A donation is a gift of land received from a non-Federal source without consideration or 

an exchange of value. 

Cooperative Management Agreements. The Service can enter into cooperative agreements with 

other organizations and landowners to improve wildlife habitat management. Cooperative 

agreements may specify shared responsibilities, or a transfer of funds from the Service to another 

entity or vice-versa for management purposes. Cooperative agreements may be applied to land under 

any type of ownership in the valley. The Partners for Fish and Wildlife program is an example of a 

successful conservation program that relies on Cooperative Agreements. 

Conservation Easements. Conservation easements are a type of acquisition where the landowner 

permanently transfers some, but not all, property rights to the Service as specified by mutual 

agreement. Under a conservation easement, a landowner would still hold title to the land with certain 

restrictions on his/her use of that land, spelled out in the easement language. The Service can acquire 

easements through purchase, donation, or exchange, depending on the terms of the easement. The 

property owner pays any applicable property taxes. 

Fee Title Acquisition. A fee title interest is normally acquired when (1) the fish and wildlife 

resources on a piece of property require permanent protection that is not otherwise available; (2) the 

property is needed for development associated with a public use; (3) a pending land use could 

otherwise harm wildlife habitats; or (4) purchase is the most practical and economical way to 

assemble small tracts into a manageable unit. Fee title acquisition transfers any property rights owned 

by the landowner, including mineral and water rights, to the Federal government. A fee title interest 

may be acquired by purchase, donation, or exchange. 

Candidate Conservation Agreements with Assurances. Candidate Conservation Agreements with 

Assurances (CCAAs) are formal agreements between the Service and one or more parties to address 

the conservation needs of proposed or candidate species, or species likely to become candidates, 

before they become listed as endangered or threatened. Landowners voluntarily commit to 

conservation actions that will help stabilize or restore the species with the goal that listing will 

become unnecessary. The goal is that actions taken under a CCAA can preclude the need for federal 

listing. Although a single property owner's activities may not eliminate the need to list, conservation, 

if conducted by enough property owners throughout the species' range, can eliminate the need to list. 
Willamette Valley Conservation Study 

28 Strategic Habitat Conservation in Oregon’s Willamette Valley 

CCAAs may benefit landowners in several ways. First, if the actions preclude listing, the landowner 

is not regulated by the Endangered Species Act. Second, if the conservation actions are not sufficient 

and the species is eventually listed, the CCAA automatically becomes a permit authorizing the 

landowner incidental take of the species. Thus, the CCAA provides landowners with assurances that 

their conservation efforts will not result in future regulatory obligations in excess of those they agree 

to at the time they enter into the Agreement. Third, for landowners who want to conserve the species 

or want to manage habitat on their land, CCAAs provides an avenue to federal or state cost-share 

programs. 

Safe Harbor Agreements. A Safe Harbor Agreement (SHA) is a voluntary agreement involving 

private or other non-Federal property owners whose actions contribute to the recovery of species 

listed as threatened or endangered under the Federal Endangered Species Act. In exchange for 

actions that contribute to the recovery of listed species, participating property owners receive formal 

assurances from the Service that if they fulfill the conditions of the SHA, the Service will not require 

any additional or different management activities by the participants without their consent. 
Willamette Valley Conservation Study 

Strategic Habitat Conservation in Oregon’s Willamette Valley 29 

Conclusion 

The Oregon State of the Environment 2000 report (OPB 2000) issued a challenge to the residents of 

the Willamette Valley, noting that development over the past 150 years had fueled economic growth, 

but had come at a cost to the valley’s natural environment. The challenge is to improve the ecological 

health of the valley while continuing economic growth and development. With rapid growth in the 

Willamette Valley projected, the time is now to address this challenge–to restore and maintain a 

network of lands across the landscape that will assist in recovering the valley’s native fish, wildlife, 

and plants, while supporting the economic viability of the valley’s working landscapes. The future is 

not inevitable, but rather, what Oregonian’s choose to create together. 

Oregon residents appear to be up for the challenge. A 2016 survey of Oregonians regarding their 

attitudes toward fish and wildlife, conducted for the Oregon Legislative Task Force on Funding for 

Fish, Wildlife, and Related Outdoor Recreation and Education (Responsive Management 2016) 

found strong support for fish and wildlife conservation in Oregon. Rating on a scale of 0 (not 

important) to 10 (extremely important), Oregon residents rated strong support for healthy fish and 

wildlife populations (9.5); for natural areas to exist for enjoying and experiencing nature (9.4); and 

for ecologically important habitats and lands in Oregon being protected and conserved (9.0). The 

Service shares and supports these values. 

The WVCS identifies important areas within which to conserve, protect, enhance, and manage areas 

for their wildlife values to improve the ecological health of the valley. The Service is committed to 

working with all parties to address the critical challenge posed by Oregon’s governors in 2000, to 

improve the ecological health of the valley while continuing economic growth and development for 

the benefit of today’s and future generations of valley residents. 

 
Willamette Valley Conservation Study 

30 Strategic Habitat Conservation in Oregon’s Willamette Valley 

This document continues on the next page. 
Willamette Valley Conservation Study 

Appendix A. Willamette Valley Conservation Plans A-1 

Appendix A. Willamette Valley Conservation Plans 

Introduction 

There is a long history of conservation planning in the Valley. A review of plans such as the Oregon 

Department of Fish and Wildlife’s Oregon Conservation Strategy (ODFW 2006), the Northwest 

Power and Conservation Council’s (NPCC) Willamette Subbasin Plan (NPCC 2004), the Willamette 

Restoration Initiative’s Willamette Restoration Strategy (WRI 2001), the Pacific Northwest 

Ecosystem Research Consortium’s Willamette River Planning Atlas (Hulse et al. 2002), the 

American Bird Conservancy’s Conservation Strategy for Landbirds in Lowlands and Valleys of 

Western Oregon and Washington (Altman 2001), the Oregon Biodiversity Project (Defenders of 

Wildlife 1998), and others reveal a variety of conservation issues as well as opportunities to address 

the issues. 

The Oregon Conservation Strategy 

The U.S. Fish and Wildlife Service (USFWS) asked each 

state to develop a wildlife action plan as part of the State 

Wildlife Grants Program. In Oregon, that plan is known as 

the Oregon Conservation Strategy (ODFW 2006). The 

Oregon Conservation Strategy (OCS) synthesized existing 

plans, scientific data, and local knowledge into a broad 

vision and conceptual framework for long-term conservation 

of Oregon’s native fish, wildlife, and habitats. It identified 

six key conservation issues that affect species and habitats 

across the state: 

 Land use changes; 

 Invasive species; 

 Disruption of disturbance regimes; 

 Barriers to animal movement—aquatic passage and 

terrestrial corridors; 

 Water quality and quantity; and 

 Institutional barriers to voluntary conservation. 

Climate change has recently been added as a seventh key conservation issue and will be addressed in 

the second edition of the OCS which is in the process of development. 

The OCS notes that land use changes, whether from conversion of native habitats to agriculture or 

agriculture to more urban uses, results in the direct loss of habitat and an increase in habitat 

fragmentation, as well as the disruption of natural disturbance regimes such as fire and floods. The 

disruption has further exacerbated the loss of rare and declining habitats such as upland prairie and 

riparian bottomland forests that depend on periodic disturbance to maintain themselves on the 

landscape. 

Invasive species cause numerous negative biologic and economic problems. Invasive species can 

negatively impact food-chain dynamics, degrade habitat conditions, increase the risk of wildfire, and 

reduce the economic output of private woodlots, farms, and ranches. Invasive species are the secondlargest contributing factor of native species becoming at-risk of extinction in Oregon (ODFW 2006). 
Willamette Valley Conservation Study 

A-2 Appendix A. Willamette Valley Conservation Plans 

Barriers to animal movement affect terrestrial species in many ways. Barriers may prevent animals 

from seasonally tracking food resources or moving between breeding, rearing, and wintering 

grounds. Barriers may also block daily movements between habitat areas and a water source. The 

range of many species is currently changing in response to climate change (Chen et al. 2011). 

Barriers to newly suitable habitat may lead to local extirpations if a species is left in an area no 

longer suitable. 

As the OCS points out, water quality and quantity are inseparable issues. Adequate flows of cool, 

well-oxygenated water are directly related to healthy populations of anadromous salmonids and 

resident fish such as the ESA-listed bull trout (USFWS 1999). This issue may become an even 

greater priority in the future as a changing climate may affect both the timing and quantity of runoff, 

leading to reduced summer base flows and warmer stream temperatures (OCCRI 2010). 

The OCS contains a suite of goals and actions to address the six key conservation issues relevant to 

this study, which include: 

 Action 1.1. Conserve strategy habitats using voluntary, nonregulatory tools such as financial 

incentives, conservation easements, landowner agreements, and targeted acquisitions. 

 Action 1.2. Encourage strategic land conservation and restoration within conservation 

opportunity areas. 

 Action 1.5. Support local land use plans and ordinances that protect farm and forest lands and 

other fish and wildlife habitats in urban and rural areas. 

 Action 4.2. Maintain and restore habitats to ensure aquatic connectivity and terrestrial 

corridors in priority areas, such as conservation opportunity areas and urban centers. 

 Action 4.6. Identify, maintain, and restore important stopover sites for migratory birds. 

 Action 6.3. Improve coordination and delivery of incentive programs to more effectively 

serve landowners and more strategically address the needs of strategy species and habitats.

Strategic Conservation Management in 

Oregon’s Willamette Valley 

The Service’s Strategic Conservation Management in 

Oregon’s Willamette Valley (USFWS 2014) initiated a 

surrogate species approach to conservation. This pilot project 

identified 10 species to represent the valley’s five key habitat 

types identified by the OCS (ODFW 2006). Some of the 

species were selected to provide insight regarding the status 

of other species (e.g., Bradshaw’s lomatium and Fender’s 

blue butterfly). Other surrogates (Oregon white oak, black 

cottonwood, and American beaver) were selected because 

they represent or determine overall habitat conditions and 

inferences on other species can be made based on the status 

and trends of the surrogates. Other species, such as western 

meadowlark and Pacific lamprey, were selected because they 

are iconic species and can be used to engage the public and 

motivate conservation actions. Preliminary biological 

objectives and priority conservation and monitoring objectives were developed for each selected 

species. Partners are now engaged in those actions. 
Willamette Valley Conservation Study 

Appendix A. Willamette Valley Conservation Plans A-3 

Recovery Plan for the Prairie Species of Western Oregon and Southwestern Washington 

The US Fish and Wildlife Service and cooperating partners developed the Recovery Plan for the 

Prairie Species of Western Oregon and Southwestern Washington (USFWS 2010). The plan outlines 

recovery actions for the five listed species at the time Fender’s blue butterfly (Icaricia icarioides 

fenderi), Willamette daisy (Erigeron decumbens), Kincaid’s lupine (Lupinus sulphureus ssp. 

kincaidii), Bradshaw’s lomatium (Lomatium bradshawii), and Nelson’s checker-mallow (Sidalcea 

nelsoniana). Each of these species is threatened by the continued degradation, loss, and 

fragmentation of their native prairie ecosystems. The strategy proposed to achieve recovery of these 

species is to restore and maintain multiple functional networks of prairie habitat capable of 

supporting viable populations of each species by protecting, restoring, maintaining, and connecting 

the remaining fragments of prairie habitats or areas with potential for restoration to prairie habitats 

within their historical range. 

National Wildlife Refuge Comprehensive Conservation Plans 

The US Fish and Wildlife Service and cooperating partners developed Comprehensive Conservation 

Plans (CCPs) for the Willamette Valley NWR Complex (W. L. Finley, Ankeny, and Baskett Slough) 

in 2011 and for the Tualatin River NWR Complex (Tualatin River and Wapato Lake) in2013. The 

purpose of each CCP is to specify a management direction for each NWR for the subsequent 15 

years. The goals, objectives, and strategies for improving Refuge conditions – including the types of 

habitats at each Refuge, partnership opportunities, and management actions needed to achieve 

desired future conditions. The CCP for the Willamette Valley NWR Complex is available at 

https://www.fws.gov/refuge/William_L_Finley/what_we_do/conservation.html. The Tualatin River 

NWR Complex CCP is available at 

https://www.fws.gov/refuge/Tualatin_River/what_we_do/planning.html 

US Fish and Wildlife Service Partners for Fish and Wildlife Five-Year Strategic Plan 

The Partners for Fish and Wildlife Program initiated work within the Willamette Valley in 1998 with 

a focus on restoring wetlands close to the existing National Wildlife Refuges. Based upon these 

initial successes, the program has grown significantly, and has enrolled approximately 250 sites into 

the program across six counties within what is now referred to as the Willamette Valley Focus Area. 

In addition to working on a broader geographic scale, the program has broadened its ecological focus 

from just wetlands to all the historic habitat types of the Willamette Valley with a strong emphasis on 

sites occupied by federally listed threatened and endangered species. This work has involved not only 

private landowners, but numerous other local, state, federal, and non-governmental conservation 

organizations allowing the Partners Program to cost effectively leverage the Service investment, 

allowing the Program to further the conservation of the valley’s native habitats. The Partners for Fish 

and Wildlife Five-Year Strategic Plan Five-Year Strategic Plan anticipates that the Partner's Program 

will remain in the vanguard of a coordinated cross-programmatic intra-Service collaborative effort to 

work with myriad conservation partners throughout the Willamette Valley in the years ahead. 

Oregon State of the Environment Report 2000 

The Oregon State of the Environment 2000 report (OPB 2000) was the first scientifically credible, 

comprehensive assessment of Oregon’s environment. It was developed by a panel of scientists from 

universities throughout Oregon and was signed by the former governors living at that time (Hatfield 

(R), Straub (D), Roberts (D), Atiyeh (R), Goldschmidt (D), and Kitzhaber (D)). The Science Panel 

found that while Oregon had made great strides in resolving some of the critical problems of the past, 
Willamette Valley Conservation Study 

A-4 Appendix A. Willamette Valley Conservation Plans 

the State still faces environmental challenges that existing programs and policies may not be 

sufficient to address. That list of issues included loss of wetlands, degraded riparian areas, depleted 

fish stocks, and diminished biodiversity. 

Specific to the Willamette Valley, the report noted that an estimated 72 percent of the original 

riparian and bottomland forest is gone, as well as an estimated 99 percent of the valley’s wet prairies, 

88 percent of upland prairies, and 87 percent of the upland forests at the margins of the valley. The 

report concludes that this transformation of the valley’s landscape “has fueled our economic growth 

and settlement for over 150 years. Yet this transformation has left a mark on our environment and a 

debt to pay” (OPB 2000). 

Willamette Subbasin Plan 

As part of the Columbia River Basin Fish and Wildlife Program, the Northwest Power and 

Conservation Council (NWPCC) prepared the Willamette Subbasin Plan (NWPPC 2004). Subbasin 

plans identify priority restoration and protection strategies for habitat and fish and wildlife 

populations. The Willamette Subbasin Plan identified habitat conversion and human manipulation of 

channel structure and hydrology as over-arching conservation-related issues in the valley. In the 

aquatic realm these modifications have blocked access to spawning areas, simplified channels which 

now lack complex habitat structures required by salmonids, reduced water quality, and changed 

discharge patterns all of which have resulted in reduced native fish populations. Upland habitat 

conversion has reduced the extent of native habitats and greatly reduced the abundance of native 

wildlife. The Plan recommended the following seven priority conservation actions for the subbasin. 

 Deal with the dams—change flow regimes and establish fish passage. 

 Fix culverts and diversions to allow fish passage. 

 Focus on valley and foothills wildlife. 

 Restore lowland riparian areas. 

 Restore low-cost, high-return areas of the Willamette 

River floodplain. 

 Let the river cool itself by seeping through streamside 

gravels, alcoves, and islands. 

 Ensure that all priority themes above are taken up and 

supported in an organized way at the local level. 

The Willamette Restoration Strategy 

The Willamette Restoration Strategy (WRI 2001) was 

developed by the Willamette Restoration Initiative (WRI), 

which was established by State Executive Order 98-18, and 

charged with developing a basin-wide strategy to protect and 

restore fish and wildlife populations, enhancing water quality, 

and properly managing floodplains within the context of 

human habitation and continued growth. The strategy identified many conservation issues in the 

basin including declining fish and wildlife populations, toxins and wastes in waters, undependable 

water supplies, and continued habitat destruction. The strategy points out that many natural resources 

are being used beyond their ability to replenish themselves and population growth and development 

continue to put pressure on the land and water. 
Willamette Valley Conservation Study 

Appendix A. Willamette Valley Conservation Plans A-5 

The strategy identified 27 actions to restore the health of the Willamette basin grouped into four 

focus areas: clean water, water quantity, habitats and hydrologic processes, and institutions and 

policies. The recommended actions include establishing science-based riparian area protection 

guidelines; inventorying, mapping, and conserving priority fish and wildlife habitats in the basin; and 

recognition of the need to create new stewardship pathways for private landowners through 

agreements and incentives. 

Willamette River Planning Atlas 

With an additional 1.7 million people expected to live in the 

Willamette River basin by 2050, the Pacific Northwest 

Ecosystem Research Consortium (PNERC) developed the 

Willamette River Planning Atlas (Hulse et al. 2002) which 

analyzed three future scenarios to depict a plausible range of 

growth alternatives in the Willamette basin. The alternatives 

range from more conservation-oriented to more market-oriented. 

The atlas documented many conservation issues in the valley 

including significant alterations to river channels and loss of offchannel habitats and floodplains, changes in the timing and 

quantity of stream discharge, degraded water quality, declines of 

fish and wildlife populations related to habitat loss, introduced 

species, contaminants, and direct human disturbance. 

The three scenarios modeled in the atlas are Plan Trend, 

Conservation, and Development. The Plan Trend scenario 

assumes existing long-term land development plans and policies 

will be fully implemented. The Development scenario assumes 

greater emphasis on short-term economic gain in making land 

and water use decisions and assumes relaxation of land use laws, resulting in fewer restrictions on 

where intensive land management may occur. The Conservation Scenario projects changes in land 

and water use patterns to prioritize conservation and ecological restoration. 

The land conservation scenario is one of the most significant actions identified in the atlas. The atlas 

describes lands to be conserved to achieve a naturally functioning landscape and lands to be managed 

for sustainable production of goods and services compatible with habitat conservation values. 

The goal of the PNERC is to: "Understand ecological consequences of possible societal decisions 

related to changes in human populations and ecosystems in the Pacific Northwest and to develop 

transferable tools to support management of ecosystems at multiple spatial scales." 
Willamette Valley Conservation Study 

A-6 Appendix A. Willamette Valley Conservation Plans 

Regional Conservation Strategy for the Greater Portland-Vancouver Region 

The Intertwine Alliance, a broad coalition of public, civic, 

private, and nonprofit organizations, developed the Regional 

Conservation Strategy for the Greater Portland-Vancouver 

Region (The Intertwine Alliance 2012a) and the companion 

document, the Biodiversity Guide for the Greater PortlandVancouver Region (The Intertwine Alliance 2012b) to build 

a common understanding of the biodiversity of the 3,000 

square mile region, define the challenges facing local 

wildlife and ecosystems, and to offer a vision and framework 

for protecting and restoring the region’s natural systems. 

Among the many strategic actions proposed by The 

Intertwine Alliance, the following are included conserve 

high-priority lands and protect existing natural areas, protect 

and acquire biodiversity corridors and core habitats, increase 

farm and forestland easements to prevent conversion to other 

uses and support the long-term economic viability of local 

farm and forestland, restore ecological processes and 

functions in natural areas, monitor changing conditions and conduct appropriate research, and 

involve citizens in protecting and managing natural areas. Specifically, the strategy calls for the 

expansion of the existing natural areas network, by formally conserving or protecting existing intact 

natural lands and lands with a high restoration potential, and by creating an interconnected system of 

natural areas, semi-natural areas, and sustainably managed working lands that together can serve 

multiple purposes and provide multiple functions. 

Northern Pacific Coast Regional Shorebird Plan 

The Northern Pacific Coast Regional Shorebird Plan (Drut and Buchanan 2000) is one of 11 regional 

plans tiered to the U.S. Shorebird Conservation Plan, 2nd edition (Brown et al. 2001) reflecting 

major shorebird flyways and habitats in the United States. The plan notes that the central and 

southern parts of the Willamette Valley are of regional importance, containing a variety of shorebird 

habitats, both wetland and agricultural, which support a wide diversity of species and large number 

of individuals. The Willamette Valley supports flocks of dunlins and common snipes and appears to 

be the most important wintering area for killdeers in the Pacific Northwest (Paulson 1993). All three 

are identified as species of high conservation concern due to either declining populations and/or the 

significance of the valley to the species. 

The plan’s habitat objectives and management needs for the Willamette Valley include acquisition or 

protection of agricultural and pasture lands adjacent to Ankeny, Baskett Slough, W.L. Finley, 

Wapato Lake, and Tualatin River National Wildlife Refuges and additional lands in the central and 

southern Willamette Valley; and areas adjacent to Jackson Bottom Wetland Preserve near Hillsboro. 

Conservation Strategy for Landbirds in Lowlands and Valleys of Western 

Oregon and Washington 

The American Bird Conservancy developed The Conservation Strategy for Landbirds in Lowlands 

and Valleys of Western Oregon and Washington (Altman 2001) to stimulate and support an active 
Willamette Valley Conservation Study 

Appendix A. Willamette Valley Conservation Plans A-7 

approach to conservation of landbirds in the lowlands and valleys of western Oregon and 

Washington. Its recommendations are intended to guide land managers’ planning efforts and actions 

and expenditures of government and nongovernment organizations, and stimulate monitoring and 

research to support landbird conservation. 

The plan identified two principal conservation issues affecting landbird populations throughout the 

Westside Lowlands and Valleys—habitat loss and degradation due directly or indirectly to an 

expanding population, and extensive private land ownership. Other issues identified include the 

change and degradation of presettlement vegetation patterns, resulting from the alterations of natural 

ecological disturbance regimes such as fire and flooding; intensification of farming practices; 

alteration of hydrological regimes, particularly in riparian habitats; habitat fragmentation; exotic and 

invasive species; logging oaks and cottonwoods; and other disturbance by humans. The plan 

proposed a landbird conservation strategy for the valley by protecting, restoring, and managing 

additional suitable habitat in proximity to existing population centers, providing habitat for dispersers 

to establish new subpopulations on newly restored habitat. This strategy was adopted by the WVCS. 

Pacific Coast Joint Venture Implementation Plan for the Willamette Valley 

The Pacific Coast Joint Venture (PCJV) Implementation Plan for the Willamette Valley (Roth et al. 

2004) identifies habitat actions in support of four major bird conservation initiatives: the North 

American Waterfowl Management Plan, Partners in Flight Implementation Plans, the U.S. Shorebird 

Conservation Plan, and the North American Waterbird Conservation Plan. 

The PCJV implementation plan identifies 15 target areas for habitat protection and restoration that 

provide important wintering and migrating habitat for waterfowl, waterbirds, shorebirds, and 

landbirds, as well as a suite of other sensitive species. These areas are primarily located along the 

mainstem of the Willamette River, around the confluence areas of the Willamette’s major tributaries; 

adjacent to national wildlife refuges and Oregon’s state wildlife areas and protected areas managed 

by other state or federal agencies, private nonprofit organizations, and local governments; and in 

areas with extensive hydric soils that have been converted to other uses. 

Oregon Statewide Comprehensive Outdoor Recreation Plan 

The State of Oregon’s 2008-2012 Statewide Comprehensive Outdoor Recreation Plan (SCORP) 

entitled Outdoor Recreation in Oregon: The Changing Face of the Future (OPRD 2008), is the State’s 

five-year plan for outdoor recreation. The purpose of the SCORP is to provide information and 

recommendations to guide federal, state, and local agencies, as well as the private sector, in making 

policy and planning decisions. The SCORP describes key planning issues such as fewer youth 

learning outdoor schools and an increasingly aging and diverse population, and makes 

recommendations to address these issues. 

Willamette Valley-Puget Trough-Georgia Basin Ecoregional Assessment 

The Willamette Valley-Puget Trough-Georgia Basin Ecoregional Assessment (Floberg et al. 2004) 

was a joint product of The Nature Conservancy, The Nature Conservancy of Canada, Washington’s 

Department of Fish and Wildlife, and the Washington and Oregon Natural Heritage Programs. 

Similar to the U.S. Fish and Wildlife Service’s Strategic Habitat Conservation process, the 

assessment identified conservation targets, set conservation goals for the targets, and identified most 

important places for conserving aquatic and terrestrial native species and habitats, including a suite of 
Willamette Valley Conservation Study 

A-8 Appendix A. Willamette Valley Conservation Plans 

conservation opportunity areas (COAs) within the valley, by using a spatially-explicit decision 

support tool (SITES). The results of this project fed directly into the Willamette Valley Synthesis 

project; a description follows. 

Oregon Biodiversity Project 

The Oregon Biodiversity Project (Defenders of Wildlife 1998) was a collaborative effort between 

conservation groups, industry, and government agencies to reduce the risk of future endangered 

species designations, provide landowners more flexibility in resource management decisions, and 

establish a process to improve communication among diverse public and private interests. The 

project conducted an assessment of biodiversity conservation needs at the statewide and ecoregion 

levels, and identified the Willamette River floodplain, the north Corvallis area, and Muddy Creek 

(including Finley National Wildlife Refuge) as high priorities for landscape-scale conservation 

efforts. 

Oregon Plan for Salmon and Watersheds 

In 1995, the State of Oregon began developing what 

became known as the Oregon Plan. The original 

strategy, called the Oregon Coastal Salmon 

Restoration Initiative, was focused on recovery of 

coastal coho salmon and improvement of water quality 

statewide. In 1997, Oregon’s Legislature expanded the 

plan’s scope and renamed it the Oregon Plan for 

Salmon and Watersheds, or the Oregon Plan. The 

Oregon Watershed Enhancement Board (OWEB) 

implements the Oregon Plan through a grant program 

with the goal of restoring and protecting rivers and 

wetlands, to provide clean water and healthy habitat 

for native fish, wildlife, and people. 

Within the Willamette Basin, OWEB has funded many 

projects to protect and restore rivers and adjacent 

riparian areas, improve fish passage, and conserve 

lands, such as assisting with the McKenzie River 

Trust’s purchase of Green Island at the confluence of 

the McKenzie and Willamette rivers and the Greenbelt 

Land Trust’s purchase of Harkins Lake in the 

Willamette River Floodplain. The Harkins Lake project is a great example of landowners coming 

together to work with our conservation partners within a voluntary, nonregulatory framework, to 

conserve and restore floodplain functions. 

Willamette Valley Synthesis Project 

Several of the plans we discussed produced spatially explicit recommendations for where 

conservation actions should be focused. Not surprisingly, a large degree of overlap exists between 

the various plans; however, there were significant differences as well. In total, the assessments 

identified nearly half of the area within the Willamette Valley Ecoregion as a priority for 

conservation. Responding to the need to get Willamette Valley conservation partners working from 
Willamette Valley Conservation Study 

Appendix A. Willamette Valley Conservation Plans A-9 

the same page, The Nature Conservancy (2012) synthesized these spatially explicit recommendations 

onto one map. In crafting the synthesis, the following assessments were considered. 

 Oregon Conservation Strategy (ODFW 2006); 

 Willamette River Basin Alternative Futures Analysis (Hulse et al. 2002); 

 Willamette Valley—Puget Trough—Georgia Basin Ecoregional Assessment (Floberg et al. 

2004); 

 Critical habitat designations and recovery plans for listed species; and 

 Oregon’s Greatest Wetlands (The Wetlands Conservancy 2005). 

 
Willamette Valley Conservation Study 

A-10 Appendix A. Willamette Valley Conservation Plans 

This document continues on the next page. 
Willamette Valley Conservation Study 

Appendix B. Climate Change B-1 

Appendix B. Climate Change 

Introduction 

Human-driven global climate change is now well underway, with serious implications for a wide 

range of ecological processes, systems, and species (IPCC 2014). In Oregon, changes in streamflow 

timing and volume, shifts in timing of life cycle events, and other effects have already been 

documented, and are likely to intensify in the coming decades. Other probable effects of climate 

change in Oregon include increasing frequency and severity of wildfires and insect pest outbreaks, 

loss of estuarine habitat due to sea level rise, increases in harmful algal blooms and oceanic “dead 

zones,” and more (OCCRI 2010). In order to help natural systems adapt to such stressors, resource 

managers need as much information as possible about likely impacts to particular species, systems, 

and places. 

Climate Change Vulnerability Assessments (CCVAs) have become a key method for understanding 

these impacts and informing adaptation planning (Glick et al. 2011). CCVAs typically break up 

vulnerability into three major components: exposure, sensitivity, and adaptive capacity (Figure B1). 

Exposure represents the external threat to the target system, species, or place from changing climate; 

sensitivity represents intrinsic qualities that make the target more susceptible to negative impacts 

from climate change (e.g., a narrow suitable temperature range); and adaptive capacity represents the 

ability of the target to cope with climate change (Glick et al. 2011). 

Figure B1. Primary components of climate change 

vulnerability, from Glick et al. 2011. 

A few CCVAs that focused on or included the Willamette Valley have already been conducted. 

While these studies used an older generation of climate models (CMIP3 [Coupled Model 

Intercomparison Project Phase 3] rather than the more recent CMIP5), Knutti and Sedláček (2013) 

demonstrated that CMIP3 and CMIP5 outputs are remarkably similar when differences in emissions 

scenarios are accounted for, and that spatial climate change patterns in the two generations are very 

consistent. Because re-running existing analyses with CMIP5 instead of CMIP3 climate data would 

yield little new information, we chose not to prepare a new CCVA, but rather to summarize the most 

important existing research. If substantially improved climate projections become available in future 

years, then new CCVAs should be conducted. 
Willamette Valley Conservation Study 

B-2 Appendix B. Climate Change 

The existing studies that are most relevant to the WVCS are the Pacific Northwest CCVA 

(PNWCCVA) developed by the University of Washington, which included a Willamette Valley case 

study (Michalak et al. 2013); The Oregon Climate Assessment Report (OCCRI 2010); and a CCVA 

for Oregon Conservation Strategy species and areas in the valley (Steel et al. 2011). These studies are 

summarized below in the “Previous Assessments” section. 

Some other key studies describe how winter temperatures have already reduced average snowpack 

depth and shifted runoff timing and volume in the Willamette Valley, and show that this pattern is 

very likely to intensify in the coming decades (Chang and Jung 2010, OCCRI 2010). To estimate 

potential changes in annual flows, seasonal flows, and extreme flow events (both highs and lows) in 

the valley, Chang and Jung (2010) developed PRMS (Precipitation Runoff Modeling System) models 

of representative Willamette River sub-basins and calibrated them to a historic period (1973-2006). 

They then ran these models with future climate inputs from a combination of two emission scenarios 

and eight downscaled general circulation models (GCMs) for both the 2040s and the 2080s. The 

results show that the seasonal variation in streamflow will likely increase. Because of decreasing 

snow pack, increasing winter precipitation, and decreasing summer precipitation, winter flows will 

be heavier and summer flows lighter. The magnitude and statistical significance of these trends is 

greater in the higher greenhouse grass emission scenario. 

A related study, based on the same PRMS models, showed that short-term (3-month) droughts will 

be increasingly likely in the lower elevation sections of Willamette Basin (Jung and Chang 2011). 

Using another hydrologic model, the VIC (Variable Infiltration Capacity) model, the University of 

Washington Climate Impacts Group also projected reduced summer and increased winter flows in the 

Willamette basin as the climate warms (OCCRI 2010). Tague et al. (2008) found that the reduced 

summer flow trend would likely be mitigated in some Cascade Mountain sub-basins with a large 

groundwater contribution to streamflow, but the WVCS study area is not among these. Additionally, 

the combination of decreased summer flow volumes and increased air temperatures will almost 

certainly lead to increases in summer water temperature (OCCRI 2010). 

These probable changes in the freshwaters systems of the Willamette Valley could have profound 

impacts on a range of species, including aquatic insects, fish, and amphibians. Increased water 

temperatures could also make the Willamette River and its tributaries more vulnerable to invasive 

aquatic species. 

Previous Assessments 

University of Washington Climate Change Vulnerability Assessment 

The University of Washington (UW) partnered with natural resource managers, scientists, and 

conservation planners from multiple organizations to conduct a CCVA for the Pacific Northwest. 

Their goal was to assess the relative (not absolute) vulnerability of species and ecological systems to 

climate change. The project had multiple components, including downscaling of global climate 

projections for the Pacific Northwest, models of suitable climate niches for various species under 

current and projected conditions, a climate sensitivity database for numerous species and ecological 

system, and models of potential vegetation type under various scenarios. As part of this study, UW 

conducted a case study for the Willamette Valley, focusing on how land managers could use the 

PNWCCVA data products to inform management decisions (Michalak et al. 2013). The findings 

from this document and from the larger study that are most relevant to the WVCS are summarized in 

Figure B2. 
Willamette Valley Conservation Study 

Appendix B. Climate Change B-3 

Figure B2. Projected changes in Mean Annual Temperature and Mean Annual 

Precipitation in the Willamette Valley. The black vertical bars show the 5-model range 

of projections. Figure modified from Michalak et al. 2013. 

Downscaled Climate Change Projections 

For the PNWCCVA, UW downscaled five general circulation models, or GCMs (CCSM3, CGM3, 

GISS-ER, UKMO-HadCM3, and MIROC3.2) using two emissions scenarios developed by the 

Fourth IPCC Assessment: A2, a relatively high emissions scenario, and A1B, a medium emission 

scenario (Nakicenovic et al. 2000). The results of these models show good agreement among climate 

projections for the Willamette Valley. All models agreed that average temperatures will increase in 

all seasons. Using projections from the ensemble mean based on the A2 (medium-high) emissions 

scenario, by the end of the century, the mean annual temperature in the Willamette is projected to 

increase by 6.2°F (individual model projections under the two emission scenarios ranged from 2.7 to 

7.9°F by the end of the century). 

There is less certainty regarding precipitation. Most (3 out of 5) models project increased annual 

precipitation, but two models project a decrease. Net annual precipitation based on the ensemble 

mean of all models is projected to increase 3 percent with individual model projections ranging from 

-9 percent to +16 percent by the end of the century. Seasonally, the majority of models project 

warmer, wetter winters and hotter, drier summers. All models consistently project drier summers and 

there is good agreement that the other three seasons will be wetter. 

Species-specific Climate Envelope Models 

Climate change puts species at risk by shifting their suitable climate envelopes outside of their 

current ranges. The magnitude of the risk depends on how quickly a species’ climate envelope shifts 

and on its ability to respond to the change. A climate envelope model uses correlations between key 

climate variables and species occurrences to identify the region that currently has a suitable climate, 

then shows where that suitable region will shift to under various future climate scenarios (Araújo and 

Peterson 2012). Climate envelope models provide an estimate for the exposure aspect of the potential 

impact formula (Figure B1). 
Willamette Valley Conservation Study 

B-4 Appendix B. Climate Change 

As a part of the PNWCCVA, UW developed climate envelope models for 366 terrestrial vertebrate 

species (Langdon 2013). Their Willamette Valley case study (Michalak et al. 2013) summarized the 

outcomes for several species of concern in the ecoregion, and found that relatively few significant 

changes are expected for those species in the valley (Table B1). A map of results for an example 

species, the western meadowlark, is shown in Figure 3. Overall, the results suggest that projected 

average climate changes do not exceed the range of average climate conditions currently tolerated by 

most of the priority conservation species in the valley. Results indicate stable conditions for Oregon 

white oak, western meadowlark, yellow-breasted chat, willow flycatcher, slender-billed whitebreasted nuthatch, common nighthawk, American beaver, northern red-legged frog, and Townsend’s 

big-eared bat. Only western red cedar and Oregon vesper sparrow showed a contracting envelope in 

the valley. Purple martins were modeled to expand their range in the valley. 

Table B1. Climate niche model results for WVCS focal species. 

Species Common Name Projected Trend in the Willamette Valley 

Oregon white oak Stable in the valley, expanding upslope and east of Cascades 

Yellow-breasted chat Stable in the valley with expansion of range northward 

Oregon vesper sparrow Stable throughout much of its range and expanding to higher 

elevations but potentially contracting in the valley 

Slender-billed white-breasted nuthatch Stable in the valley and region 

Western meadowlark Stable in the valley and region 

There are a few important caveats to these results. First, climate change may lead to increases in the frequency and 

severity of extreme weather events, such as heatwaves or flooding, and these climate models do not reflect that possibility. 

Second, these habitat suitability models do not include important ecological processes and interactions such as 

competition, dispersal, disease, and stochastic events such as fires. Finally, only two future climate models were used; a 

larger sample of GCMs would provide a fuller picture of the range of possible outcomes.

Figure B3. Climate 

niche modeling results 

for the western 

meadowlark. Most of

the Willamette Valley 

was mapped as 

climatically suitable 

under both current and 

future conditions. 

Figure from Michalak et 

al. 2013. 
Willamette Valley Conservation Study 

Appendix B. Climate Change B-5 

Plant Functional Types Model 

In contrast to the vertebrate climate niche models, results from the UW’s mechanistic vegetation 

models suggest a much more dynamic future. 

They simulated future potential vegetation under climate change in the Pacific Northwest using the 

Lund-Potsdam-Jena (LPJ) global vegetation model (Sitch et al. 2003). LPJ models the potential 

distribution of plant functional types (e.g., temperate forests or grasslands) rather than individual 

species. To do this, it simulates numerous mechanistic processes, such as competition, wildfire, and 

photosynthesis among other attributes. 

Under mild climate change scenarios, the functional vegetation types in the region are projected to 

remain fairly stable, but with more extreme climate models, substantial shifts in vegetation are 

projected (Rogers et al. 2011). These changes are largely driven by an increase in summer water 

stress due to increased temperatures and reduced precipitation during summer, which leads to 

increases in major fires and thus allows for dramatic shifts in vegetation type. These potential firedriven vegetation shifts may be avertable via active fuel load management and fire suppression as 

would likely happen in a developed landscape such as the Willamette Valley. 

Land conversion to development and agriculture combined with Douglas fir encroachment has 

reduced the extent of oak woodlands to a fraction of their historical range (Larsen and Morgan 1998). 

The UW climate projections suggest that conditions may improve for this species in the Willamette 

Valley and even in some lower elevation areas adjacent to the Valley. If Douglas fir begins to die 

back due to increased summer drought or insect pest outbreaks, managers may be able to facilitate 

transformation to Oregon white oak and prairie systems (Bachelet et al. 2011). 

Climate Sensitivity Database 

Another relevant component of the PNWCCVA is the Climate Change Sensitivity Database 

(http://climatechangesensitivity.org/), which provides information about the inherent climate-change 

sensitivities of habitats and species of conservation concern in the Pacific Northwest. The database 

provides an estimate for the sensitivity aspect of the potential impact formula (Glick et al. 2011) 

(Figure B1). The database contains hundreds of records, including numerous species of concern 

within the Willamette Valley. As part of the ecoregion’s case study, Michalak et al. (2013) 

highlighted several of these species (Figure B4Error! Reference source not found.). Two species of 

frogs have the highest sensitivity (along with relatively high confidence values for that vulnerability 

score) while many bird species are less sensitive. 

There are a few key limitations to the sensitivity database. First, because empirical data on the 

sensitivities of many species are unavailable, many of the scores are based primarily on expert 

judgment and are dependent on untested assumptions. Also, the sensitivity database is not spatially 

explicit, and assumes that each species has a homogenous sensitivity to climate change within the 

Pacific Northwest. 

While western bluebird was estimated to be sensitive to the effects of climate change, its climate 

envelope model suggests that the exposure component of the Glick et al. (2011) climate change 

vulnerability formula (Figure B1) may not be substantial, meaning that the potential impacts related 

to climate change may not be significant. This same situation applies to other species the database 

rates as sensitive to climate change. The climate envelope models suggest that the average projected 

climate change in the valley will not exceed the range of average climate conditions currently 
Willamette Valley Conservation Study 

B-6 Appendix B. Climate Change 

tolerated by northern red-legged frog, Townsend’s big-eared bat, yellow-breasted chat, slender-billed 

white-breasted nuthatch, and others, even though they would sensitive to substantial climate changes 

should those changes occur. 

Oregon Climate Assessment Report 

The Oregon Climate Change Research Institute (OCCRI) is a network of over 100 researchers 

associated with the Oregon University System and its partner organizations. In 2007, OCCRI was 

asked to prepare an assessment of climate change knowledge in Oregon by the State Legislature (HB 

3543). In 2010, they published a summary of climate science for the state that describes impacts that 

have already been documented, likely future effects of climate change, and current knowledge gaps 

(OCCRI 2010). Some of the assessment’s key findings of greatest relevance to terrestrial systems in 

the Willamette Valley follow. 

 Summers will be warmer and drier (the ensemble average decrease for summer precipitation 

is 14% by the 2080s). 

 As warm, dry summers increase, forests of all types will be more susceptible to wildfire. In 

forests west of the Cascades that were historically too cool and moist to burn extensively, 

heavy fuels loads could drive large fires. 

 Climate change will lead to shifts in the distribution and abundance of numerous species of 

animals and plants. 

 Invasive species and insect pests may become more abundant. 

Figure B4. WV species of concern in the UW Climate Change Sensitivity Database. 

Blue bars indicate percent sensitivity (relative to the maximum possible score), and red 

bars indicate percent confidence in that score (relative to maximum possible). Figure 

from Michalak et al. 2013. 
Willamette Valley Conservation Study 

Appendix B. Climate Change B-7 

University of California, Davis CCVA for the Willamette Valley 

In consultation with the Oregon Department of Fish and Wildlife and the Defenders of Wildlife, a 

group of graduate students from the University of California, Davis assessed the relative climate 

change vulnerability of the valley’s priority species and areas (Steel et al 2011) as defined by the 

Oregon Conservation Strategy (ODFW 2006). They scored 46 of the valley’s 59 strategy species 

using the Climate Change Vulnerability Index developed by NatureServe (Young et al. 2010), and 

assessed the relative vulnerability of the valley’s 27 COAs (as defined in ODFW 2006) using an 

index that combined climatic and nonclimatic stressors. They found that birds, on average, were the 

least vulnerable group of species, and that plants, fishes, and invertebrates tended to be the most 

vulnerable species in the valley. In their analysis of the COAs, they found that non-climatic factors 

such as human impact and invasive species had a more significant effect on the overall vulnerability 

score than did climate change. This suggests, as does Michalak et al. (2013) and Bachelet et al. 

(2011), that climate change may not be as severe in the valley as in some other areas, and that there 

are other critical issues that may need to be addresses first, or at least simultaneously. 

Climate Change Velocity 

Climate change velocity also suggests that, relative to other regions in Western North America 

(WNA), the Willamette Valley may experience less significant climate change impacts. Climate 

change velocity, first proposed by Loarie et al. (2009), represents the speed, in kilometers per year, at 

which an organism would have to move across the landscape in order to maintain constant climatic 

conditions, which is calculated using a combination of climate change and elevation data. 

Climate change velocity is relatively high in areas with little topographic complexity, such as the 

central Columbia Plateau, because climate is consistent over large areas and organisms would have to 

travel long distances to find very different climatic conditions. 

Conversely, in areas with high topographic complexity (i.e., mountain ranges), climate velocities are 

relatively low because local conditions change quickly with movement up slope or to different 

aspects. Near the peaks of mountains, however, the velocity can be extremely high because historical 

climatic conditions can entirely disappear from the mountain, requiring organisms to move to distant 

locations to find a suitable climate (Loarie et al. 2009). 

Hamann et al. (2014) recently released a set of climate change velocity rasters for WNA using a 

refined algorithm as well as higher spatial resolution (1 km pixels) than was available in previous 

climate change velocity datasets. Figure B5 shows two of the Hamann et al. climate change velocity 

models over most of WNA, with the Willamette Valley outlined in black. 

The panel on the left of Figure 5 shows climate change velocity based on 12 biologically relevant 

climate variables, while the panel on the right shows the velocity of mean annual temperature alone. 

In both cases, the Willamette Valley has a low exposure to climate change compared to other 

regions. 

Table B2 shows the mean, minimum and maximum values across the entire extent of the datasets, as 

well as the mean for the Willamette Valley. For temperature climate change velocity, the WNA mean 

is 9.9 times higher than the valley average, and for multivariate climate velocity, the WNA mean is 

3.7 times higher than the valley average. This dataset thus lends further support to the idea, suggested 

by the UW PNWCCVA, that many of the priority species and systems of the Willamette Valley are 

less vulnerable to climate change than those in other regions of the Pacific Northwest and WNA. 
Willamette Valley Conservation Study 

B-8 Appendix B. Climate Change 

Figure B5. Climate Change Velocity for Western North America from Hamann et al. 2014. Both 

metrics are based on the differences in mean values for 1961-1990 and 2041-2070, and use the A1B 

emissions scenario with a 7 GCM ensemble. 

Table B2. Statistics for variables shown in Figure B5 over the entire dataset extent (WNA) and the 

Willamette Valley only. 

Values 

Multivariate 

Climate Change velocity 

(km/yr) 

Mean Annual Temperature 

Climate Change Velocity 

(km/yr) 

Minimum for WNA 0 0 

Maximum for WNA 49.06 24.64 

Mean for WNA 4.32 2.48 

Mean for the Willamette Valley 1.17 0.25 
Willamette Valley Conservation Study 

Appendix B. Climate Change B-9 

Figure B6. Relative resilience to climate change in 

the Willamette Valley (Buttrick et al. 2014).

Climate Change Resilience 

Just as the Hamann et al. (2014) climate velocity models can serve as a metric of climate change 

exposure, a recent geospatial analysis by Buttrick et al (2014) developed a model of relative 

resilience to climate change based on microclimate diversity and permeability that provides a metric 

of relative adaptive capacity across the landscape. They argue that two variables, microclimate 

diversity and landscape permeability, are key to climate change adaptation. Areas with high 

microclimate diversity can serve as climate refugia, increasing the likelihood of species persistence, 

and good landscape permeability allows organisms to relocate to a more suitable microclimate as 

their climate envelopes shift across the landscape. 

Microclimate diversity is a combination of 

two indices, both derived from a 30m digital 

elevation model. The first is the heat load 

index, a proxy for relative local temperature 

based on slope, aspect, and latitude, and the 

second is the compound topographic index, 

which estimates relative soil moisture 

potential based on contributing upstream areas 

and slope. Permeability, which measures how 

readily terrestrial organisms can move through 

the landscape, requires a resistance surface as 

an input layer. Resistance is based on the land 

cover type of a pixel, with roads and other 

developed land cover types having high 

resistance to ecological flows, agricultural 

pixels having moderate resistance, and natural 

types having low resistance. Permeability was 

calculated for each pixel in a resistance 

surface by testing how well connected a pixel 

was to other pixels in its neighborhood. 

Permeability and microclimate diversity were 

then combined into a single raster model of 

climate change resilience (Buttrick et al. 

2014). 

To assist with the WVCS, TNC clipped out 

the Wilmette Valley section of the resilience 

model, and then calculated the density of 

pixels that were among the most resilient 40 percent within the valley. The resulting climate change 

resilience index (Figure 6) provides a depiction of relative climate change resilience across the 

Valley. 

The blue areas in Figure B6 have the highest relative resilience. They are generally at the edges of 

the valley, where more complex topography allows for high microclimate diversity, and where 

permeability is higher because of connection to the more intact areas in the mountains that surround 

the valley. Because most of these blue areas are dominated by Douglas fir forests, which are not 

priority habits for the WVCS, the PCAs mostly do not overlap with them. The lowest scoring areas 

of the valley, shown in orange, are in the urban centers and agricultural heartland at the valley 

bottom. The PCAs mostly do not overlap with these areas, but tend to fall in the middle range of 
Willamette Valley Conservation Study 

B-10 Appendix B. Climate Change 

resilience. One exception is the Indian Head Hills area near Coburg, which is more resilient than 

most of the PCAs. This information could potentially be used to prioritize PCAs with higher 

resilience for protection, or to identify low resilience areas where “climate smart” management 

strategies (as described in Stein et al. 2014) may be needed. 

Conclusions and Possible Future Research 

Taken together, the existing studies suggest that the priority species and habitats of the WVCS are 

less vulnerable to climate change than many ecosystems and species in the broader region. Some 

priority habitats, such as prairies, savannas, and oak woodland may actually fare better under 

predicted climate change conditions (Bachelet et al. 2011). Climate niche models indicate that the 

WVCS priority bird species are fairly resilient to climate change (Michalak et al. 2013). 

This does not mean that climate change will not be a serious issue, but it does imply that protection 

from other threats such as invasive species and habitat conversion may be equally or more important 

in terrestrial systems. In aquatic systems, however, climate change impacts will be more severe, and 

analysis suggests that the valley’s rare plant and insect species may also be vulnerable (Steel et al. 

2011). 

Because of the relatively low vulnerability of the WVCS species and systems as well as the large 

body of existing research on Willamette Valley climate change impacts, we concluded that another 

CCVA was not required at this point. A new region-wide CCVA should be completed when 

improved data sets become available. For example, if a new generation of regional climate models 

were developed, it might reduce the uncertainty in precipitation projections or in the frequency of 

extreme weather events such as flooding and prolonged heat waves (Dulière et al. 2011). Such data 

would allow for a more definite understanding of the likely effects of climate change on the WVCS 

priority habitats and species. 

Other key uncertainties relating to climate change are its effects on invasive species, large fires west 

of the Cascades, and the human population growth rate, which may increase if climate refugees are 

driven out of drought-stricken regions to the south. As new research on these important topics 

becomes available, their results should be incorporated into Willamette Valley conservation planning 

and management. 

Wapato Lake and surrounding area. USFWS 
Willamette Valley Conservation Study 

Appendix C. Priority Habitats C-1 

Appendix C. Priority Habitats 

Introduction 

The native habitats that species were selected to represent are the declining and in some cases now 

rare land cover types that were once common across the Willamette Valley. The habitats, identified 

by the Oregon Department of Fish and Wildlife (ODFW) as “strategy habitats” in the Oregon 

Conservation Strategy (ODFW 2006), include Grasslands (including oak savanna), oak woodlands, 

wetlands (including wet prairies), riparian, and aquatic habitats. We used the ecological systems 

nomenclature of the International Terrestrial Ecological Systems Classification (NatureServe 2011) 

to identify the following Willamette Valley strategy habitats and ecological systems—Willamette 

Valley Upland Prairie and Savanna, Willamette Valley Wet Prairie, North Pacific Oak Woodland, 

North Pacific Lowland Riparian Forest and Shrubland, and Temperate Pacific Freshwater Emergent 

Marsh. Ecological systems are recurring groups of biological communities that are found in similar 

physical environments and are influenced by similar dynamic ecological processes, such as fire or 

flooding (Comer et al. 2003). 

Some of these systems are endemic to the valley, meaning they are only found in the valley and 

immediate vicinity. These systems once covered about two-thirds of the valley, but each has 

experienced dramatic declines since Euro-American settlement began in earnest a little over 150 

years ago (Christy and Alverson 2011; Taft and Haig 2003). Conserving and restoring these systems 

and the native species they host is a constant theme of the Oregon Conservation Strategy (ODFW 

2006) and other conservation plans developed for the valley (NWPCC 2004; Floberg et al. 2004; 

Altman 2001). 

Willamette Valley Upland Prairie and Savanna 

The Willamette Valley Upland Prairie and Savanna system is endemic to the Willamette Valley and 

the Puget Trough of Washington State (NatureServe 2011). Prior to settlement, it formed a complex 

mosaic of varying patch sizes with wet prairies and riparian forests over much of the Willamette 

Valley. It occurs on well-drained, deep soils and was maintained historically by frequent 

presettlement low-intensity fires (Johannessen et al. 1971, Christy and Alverson 2011). In the 

savannas, Oregon white oak (Quercus garryana) is the dominant tree species, but as is typical of 

savanna habitat, trees only occur at low densities, providing less than 30 percent cover. In the 

absence of disturbance such as fire, conifers invade this system and many historic savannas have 

converted to forest (Christy and Alverson 2011, ODFW 2006). This process of habitat loss through 

succession continues to this day. Succession is the process of change in an ecosystem brought about 

by the progressive replacement of one community by another in a definite order until a stable 

community (i.e. climax community) is established. 

The Willamette Valley Upland Prairie and Savanna system is comprised of five component plant 

associations (NatureServe 2011) dominated primarily by graminoids, such as California oatgrass 

(Danthonia californica), Roemer’s fescue (Festuca roemeri), and bearded wheatgrass (Elymus 

caninus). Oregon white oak is the dominant tree species although ponderosa pine (Pinus ponderosa) 

savannas are also present. A plant associations is a vegetation classification unit defined on the basis 

of a characteristic range of species composition, diagnostic species occurrence, habitat conditions, 

and physiognomy. 
Willamette Valley Conservation Study 

C-2 Appendix C. Priority Habitats 

Oak savannas historically covered about 540,000 acres or 17 percent of the valley. Upland prairie 

was the most extensive prairie type in the valley, covering approximately 707,000 acres or about 22 

percent of the valley (Christy and Alverson 2011). 

Today, less than one percent of this habitat remains as remnant patches scattered across the valley, 

making the Willamette Valley Upland Prairie and Savanna one of the most critically endangered 

ecosystems of the United States (Noss et al. 1995). Oak savanna in Washington, Oregon, and 

California has been designated by the American Bird Conservancy as one of the 20 most threatened 

bird habitats in the United States (ABC 2006). Grassland birds are among those that have 

experienced the steepest population declines in the U.S. (Rosenberg et al., 2016) 

Related to this loss has been a substantial decline of wildlife populations dependent on this habitat, 

resulting in several imperiled species being listed under the Endangered Species Act with more 

identified as species of conservation concern (ODFW 2008). Altman (2011) documents the 

extirpation of five prairie-oak bird species from the Willamette Valley since the 1940s: Lewis’s 

woodpecker (Melanerpes lewis), Say’s phoebe (Sayornis saya), short-eared owl (Asio flammeus), 

western burrowing owl (Athene cunicularia hypugaea), and lark sparrow (Chondestus grammacus). 

Plant species native to upland prairie various species of grasses such as California oatgrass 

(Danthonia californica), Roemer’s fescue (Festuca roemeri), bearded wheatgrass (Elymus caninus), 

Sandberg bluegrass (Poa secunda), prairie Junegrass (Koeleria macrantha), Lemmon’s needlegrass 

(Achnatherum lemmonii), and slender wheatgrass (Elymus trachycaulus). Native perennial forbs 

include Oregon sunshine (Eriophyllum lanatum), slender cinquefoil (Potentilla gracilis), dwarf 

checkermallow (Sidalcea virgata), lance selfheal (Prunella vulgaris ssp. lanceolata) and Tolmie 

startulip (Calochortus tolmiei). 

Listed species and species of conservation concern associated with the Willamette Valley Upland 

Prairie and Savanna system include: Fender’s blue butterfly (Icaricia icarioides fenderi syn. Plebejus 

icarioides fenderi), Taylor’s checkerspot butterfly (Euphydryas editha taylori), streaked horned lark 

(Eremophila alpestris strigata), western meadowlark (Sturnella neglecta), Oregon vesper sparrow 

(Pooecetes gramineus affinis), western burrowing owl, Lewis’ woodpecker, band-tailed pigeon 

(Patagioenas fasciata), camas pocket gopher (Thomomys bulbivorus), golden paintbrush (Castilleja 

levisecta), Kincaid’s lupine (Lupinus sulphureus ssp. kincaidii), shaggy horkelia (Horkelia congesta

ssp. congesta), Bradshaw’s lomatium (Lomatium bradshawi), Willamette Valley daisy (Erigeron 

decumbens), peacock larkspur (Delphinium pavonaceum), white-rock larkspur (Delphinium 

leucophaeum), and thin-leaved peavine (Lathyrus holochlorus).

Western meadowlark/USFWS 
Willamette Valley Conservation Study 

Appendix C. Priority Habitats C-3 

Willamette Valley Wet Prairie 

At the time of settlement, Willamette Valley wet 

prairies occurred as a mosaic of emergent marsh, 

seasonally flooded grasslands, Oregon ash 

(Fraxinus latifolia) swales, and vernal pools. 

They were a common feature, covering about 

340,000 acres or approximately 10 percent of the 

valley. Wet prairies were maintained on the 

landscape by a combination of the wetland soil 

hydrology and frequent low intensity fires. 

The Oregon State of the Environment Report 

2000 (OPB 2000) estimated that 99 percent of 

the valley’s original wet prairies are gone. Today 

this system occurs as widely dispersed habitat 

patches, generally in poor condition relative to historic conditions. They are located primarily on the 

heavy clay soils of the valley floor that are either perennially saturated or flooded during the winter 

and early spring (Christy and Alverson 2011). 

The Willamette Valley Wet Prairie system is comprised of seven component plant associations 

(NatureServe 2011), dominated primarily by graminoids, especially tufted hairgrass (Deschampsia 

caespitosa), rushes (Juncus spp.), and sedges (Carex spp.). Perennial and annual forbs such as 

common camas (Camassia quamash ssp. maxima), great camas (Camassia leichtlinii ssp. suksdorfii), 

coyote-thistle (Eryngium petiolatum), and elegant downingia (Downingia elegans) are also 

commonly found in wet prairies (IAE 2010). 

Listed species and species of conservation concern associated with the Willamette Valley Wet Prairie 

system include northern harrier (Circus cyaneus), short-eared owl (Asio flammeus), American grass 

bug (Acetropis americana), Bradshaw’s lomatium, shaggy horkelia (Horkelia congesta), Nelson’s 

checkermallow (Sidalcea nelsoniana), racemed goldenweed (Pyrrocoma racemosa var. racemosa), 

white-topped aster (Sericocarpus rigidus), and Willamette Valley daisy. 

North Pacific Lowland Riparian Forest and Shrubland 

The North Pacific Lowland Riparian Forest and Shrubland ecological system includes habitats also 

known as bottomland hardwood forests, gallery forests, wetland or riparian forests, riparian 

shrublands, and willow shrublands. It occurs from Oregon through Washington and British Columbia 

and into the temperate lowlands of Alaska. This wide-ranging system is comprised of 57 different 

plant associations (NatureServe 2011). 

At the time of settlement, riparian and wetland forests covered about 240,000 acres, or about 7 

percent of the valley. Shrublands covered an additional 13,000 acres, or about 0.4 percent of the 

valley. These forests and willow-dominated shrublands occur on low-elevation floodplains and lower 

terraces of rivers and streams. They are generally linear in character following a river or stream, but 

prior to settlement and subsequent land clearing, could extend up to 10 miles from the Willamette 

River (Christy and Alverson 2011). 

In the Willamette Valley, dominant broadleaf species include bigleaf maple (Acer macrophyllum), 

red alder (Alnus rubra), black cottonwood (Populus balsamifera ssp. trichocarpa), Sitka willow 

Willamette Valley wet prairie/©Steve Gisler, 

ODOT 
Willamette Valley Conservation Study 

C-4 Appendix C. Priority Habitats 

(Salix sitchensis), Pacific willow (Salix lucida ssp. lasiandra), red-osier dogwood (Cornus sericea), 

and Oregon ash (Fraxinus latifolia). Conifers tend to increase with succession in the absence of 

major disturbance such as floods or fires. Riverine flooding and the succession that occurs after 

major flood events are the primary ecological processes that perpetuate this system. Very earlysuccessional stages can be sparsely vegetated or dominated by herbaceous vegetation. 

Listed species and species of conservation concern associated with the North Pacific Lowland 

Riparian Forest and Shrubland ecological system include willow flycatcher (Empidonax traillii), 

yellow-breasted chat (Icteria virens), purple martin (Progne subis), yellow-billed cuckoo (Coccyzus 

americanus), western pond turtle (Actinemys marmorata), northern red-legged frog (Rana aurora), 

Oregon spotted frog (Rana pretiosa), Oregon slender salamander (Batrachoseps wrightorum), 

Nelson’s checker-mallow, Oregon giant earthworm (Driloleirus macelfreshi), silver-haired bat 

(Lasionycteris noctivagans), Yuma myotis (Myotis yumanensis), Camas pocket gopher (Thomomys 

bulbivorus), and white-footed vole (Arborimus albipes). 

The Oregon State of the Environment Report (2000) estimated that about 72 percent of the valley’s 

original riparian and bottomland forest has been converted to other uses (OPB 2000). 

Snagboat Bend provides habitat for western pond turtles, herons, and other 

species/© Joe Staff 
Willamette Valley Conservation Study 

Appendix C. Priority Habitats C-5 

North Pacific Oak Woodland 

The North Pacific Oak Woodland system occurs primarily in the Willamette Valley and 

Washington’s Puget Trough. It typically occurs along the ecotone between upland prairie and 

savanna habitats and conifer-dominated forests found at higher elevations in the valley foothills 

(Christy and Alverson 2011). An ecotone is a transition area between two systems or plant 

communities that may be a gradual blending of the communities or a sharp boundary line. This 

system is comprised of eight component plant associations in which Oregon white oak is either the 

sole dominant tree species or codominant with Douglas fir (Pseudotsuga menziesii) (NatureServe 

2011). It is associated with dry, predominantly higher-elevation sites within the valley. These sites 

likely experienced presettlement low-intensity fires, but stand density and a brushy understory 

suggest that burning was less frequent in woodlands than in prairie or savanna habitats, but was more 

frequent than in closed forests (Christy and Alverson 2011). In the absence of fire, succession tends 

to favor increased shrub dominance in the understory, increased tree density, and increased cover by 

conifers, especially Douglas fir, with the end result being conversion to a conifer forest and loss of 

oak woodland habitat (NatureServe 2011). 

Prior to settlement, woodlands with an oak component occurred on approximately 330,000 acres or 

about 10 percent of the valley. Oak was either the dominant species or occurred in combination with 

Douglas-fir, big-leaf maple, and Ponderosa pine (Christy and Alverson 2011). The Oregon State of 

the Environment Report (2000) reported that about 87 percent of the upland forests at the margins of 

the valley have been converted to other uses (OPB 2000). 

Common native plant species in oak woodlands include blue wildrye (Elymus glaucus), common 

camas, Pacific blacksnakeroot (Sanicula crassicaulis), poison-oak (Toxicodendron diversilobum), 

common snowberry (Symphoricarpos albus), and sword fern (Polystichum munitum). 

Listed species and species of 

conservation concern associated with 

the North Pacific Oak Woodland 

system include: acorn woodpecker 

(Melanerpes formicivorus), Lewis’ 

woodpecker, olive-sided flycatcher 

(Contopus cooperi), Oregon vesper 

sparrow, band-tailed pigeon, Oregon 

slender salamander, Bradshaw’s 

lomatium, and thin-leaved peavine. 

Red-legged frogs use this habitat 

during their summer migration from 

wetlands to upland habitat (IAE 

2010). 

William L. Finley National Wildlife Refuge/© Joe Staff 
Willamette Valley Conservation Study 

C-6 Appendix C. Priority Habitats 

Temperate Pacific Freshwater Emergent Marsh 

The Temperate Pacific Freshwater Emergent Marsh system includes wetlands dominated by 

emergent, typically herbaceous vegetation. This system is associated with groundwater discharge or 

seasonally high water tables. Standing water may be seasonally present, most often during the winter 

and spring months. In some areas, water table fluctuations occur to a degree that soil surfaces may 

dry and bare ground may be exposed by later summer. Today, this system mostly occurs as small 

patches confined to limited areas in suitable floodplain, topographic depressions, or along the 

margins of ponds and lakes (Rocchio and Crawford 2009). 

All larger historical emergent wetlands such as Lake Labish north of Salem, and Lousignont Lake 

and Wapato Lake near Forest Grove have been drained and converted for agricultural use (Christy 

and Alverson 2011), however, the historic Wapato Lake is now part of the Wapato Lake National 

Wildlife Refuge and actions are being planned to restore the historic lakebed. The Oregon State of 

the Environment Report reported that about 57 percent of the Willamette Valley’s original freshwater 

wetlands have been lost and 44 percent of the valley’s historical wetland plant communities are 

considered imperiled (OPB 2000). And the loss is ongoing. The report noted ongoing wetland loss, 

citing an Oregon Department of State Lands (ODSL) report that between 1982 and 1994 

approximately 6,877acres of wetland (including wet prairie) were lost, despite the State’s policy of 

no net loss of wetlands (OPB 2000). In an updated look, ODSL reported a net loss of an additional 

3,960 acres of wetland in the Willamette Valley between 1994 and 2005 (Morlan et al. 2010). 

By definition, freshwater marshes are dominated by emergent herbaceous species, mostly graminoids 

including native and nonnative grasses such as tufted hairgrass (Deschampsia caespitosa),meadow 

foxtail (Alopecurus pratensis), western mannagrass (Glyceria occidentalis), sedges, rushes, bulrushes 

(Scirpus spp.), and spikerushes (Eleocharis spp.). Forbs are also present including beggarticks 

Great egret at Wapato Lake/© Chuck and Grace Bartlett 
Willamette Valley Conservation Study 

Appendix C. Priority Habitats C-7 

(Bidens spp.), wapato (Sagittaria latifolia), and monkey-flower (Mimulus spp.). Trees and shrubs 

occur peripherally or on elevated microsites and include species such as Oregon ash, alders (Alnus 

spp.), willows (Salix spp.), red-osier dogwood (Cornus sericea), Pacific ninebark (Physocarpus 

capitatus), and Douglas spirea (Spiraea douglassii). Two nonnative, invasive species in particular, 

reed canarygrass (Phalaris arundinacea) and purple loosestrife (Lythrum salicaria), can form large, 

monotypic stands greatly decreasing a wetland’s value to native wildlife. 

Wetlands play a critical role in meeting the life-history requirements of many native migratory and 

resident wildlife species. Dabbling ducks such as shovelers, teals, wigeons, and mallards (Anas 

platyrhynchos) feed; and shorebirds such as common snipe (Gallinago gallinago), yellowlegs 

(Tringa spp.), sandpipers (Calidris spp.), and plovers (Charadrius spp.) feed and breed in emergent 

wetlands. Reptiles such as the western pond turtle, western painted turtle (Chrysemys picta); and 

amphibians such as northwestern red-legged frog, northwestern salamander (Ambystoma gracile), 

and rough-skinned newt (Taricha granulosa); are all closely associated with emergent wetlands. 

Rivers and Streams 

The valley’s rivers and streams have been altered considerably since the time of Euro-American 

settlement and populations of native fish and other aquatic organisms have declined as a result. 

Listed species include the Upper Willamette and Lower Columbia River evolutionarily significant 

units (ESUs) of Chinook salmon (Oncorhynchus tshawytscha), the Lower Columbia River ESU of 

coho salmon (Oncorhynchus kisutch), the Upper Willamette River and Lower Columbia River ESUs 

of steelhead trout (Oncorhynchus mykiss), Oregon chub (Oregonichthys crameri), and bull trout 

(Salvelinus confluentus). Other species of conservation concern include Pacific lamprey (Lampetra 

tridentate), coastal cutthroat trout (Oncorhynchus clarki ssp.), and freshwater muscles such as the 

Oregon floater (Anodonta oregonensis). An ESU is a population or group of populations that are 

substantially reproductively isolated from other conspecific populations and that represents an 

important component of the evolutionary legacy of the species. 

Prior to settlement, the Willamette River from today’s Eugene to Albany occurred as a wide swath of 

braided channels, wetlands, bottomland hardwood forests, and riparian shrublands (Hulse et al. 

2002). In places, the forests extended out from the river for up to 10 miles. The valley regularly 

flooded and the flood water deposited silts and nutrients that over time helped create the valley’s 

exceptional agricultural soils (ODFW 2006). Annual flooding also assisted in the creation and 

maintenance of the bottomland forests and shrublands as well as creating nesting habitat for the 

streaked horned lark, a species that prefers to construct its nest on bare ground. 

As settlement increased, flooding posed an ever increasing risk to life and property. To abate the risk, 

dams were built and revetments were constructed along the river’s banks. During the period from 

1850 to 1995, over 40 percent of the total area of river channels and islands was lost, reduced from 

41,000 acres to less than 23,000 acres. More than 25 percent of the total length of all channels was 

lost, reduced from 355 miles to 264 miles (Hulse et al. 2002). More than one-half of the area of small 

tributary floodplains and more than one-third of the alcoves and sloughs were lost by 1995 (Hulse et 

al. 2002). 

Between 1941 and 1968, the U.S. Army Corps of Engineers built a system of 13 multi-purpose dams 

and reservoirs with the primary purpose of flood control. Dams are located on the Tualatin, Long 

Tom, Santiam, McKenzie, Middle Fork Willamette, and Coast Fork Willamette rivers. Most of the 

dams do not provide for fish passage and as flood control dams, have greatly affected the frequency 

and extent of downstream flooding (Hulse et al. 2002). 
Willamette Valley Conservation Study 

C-8 Appendix C. Priority Habitats 

Bull trout/USFWS
Willamette Valley Conservation Study 

Appendix D. Selection Criteria D-1 

Appendix D. Selection Criteria 

Introduction 

Because it is impractical to develop conservation prescriptions for all species present in a study area 

as large as the Willamette Valley, a subset of species was selected to represent each of the priority 

habitat types under the assumption that by implementing management strategies that support the 

ecological conditions favored by the target species, the needs of the larger set of species 

characteristic of that habitat will also be met (USFWS 2012a). 

The goal of the species selection approach was to select species that best represent the priority habitat 

types and meet practical management considerations. For example, it makes little sense to select a 

species that well represents a habitat and its associated species, if monitoring that species is so 

difficult it entails great cost or effort. 

The species selection process began by developing a list of species that could represent the habitat 

types and a list of criteria against which each species would be scored. 

Species Selected for Evaluation as Conservation Targets 

The initial selection of species to be evaluated was based on their inclusion as focal species in the 

CCPs for Willamette Valley National Wildlife Refuge Complex and the Tualatin River National 

Wildlife Refuge (USFWS 2011, USFWS 2013a); the OCS (ODFW 2006); the Conservation Strategy 

for Landbirds in Lowlands and Valleys of Western Oregon and Washington (Altman 2001); and the 

Pidgeon Butte Ridge looking east/© Joe Staff 
Willamette Valley Conservation Study 

D-2 Appendix D. Selection Criteria 

Willamette Subbasin Plan (NPCC 2004); as well as consideration of their distribution and habitat 

affinities. The initial species list was sent to biologists and scientists with expertise in the valley who 

would eventually score the species and was adjusted based on comments received. The list of species 

evaluated for each priority habitat type is provided in Table D1. 

Table D1. Species Selected for Evaluation 

Prairie Oak Savanna Oak 

Woodland 

Riparian 

Forest 

Riparian 

Shrubland Wetlands Riverine 

Bradshaw's 

lomatium 

American 

kestrel 

Acorn 

woodpecker 

Brown 

creeper 

Common 

yellowthroat Dunlin Bull trout 

Golden 

paintbrush 

Fender's blue 

butterfly 

Band-tailed 

pigeon 

California 

myotis 

Northern redlegged frog Dusky 

Canada goose 

Chinook 

salmon 

Nelson's 

checkermallow 

Kincaid's 

lupine 

Black-capped 

chickadee 

Downy 

woodpecker 

Swainson's 

thrush 

Great blue 

heron 

Coastal 

cutthroat 

trout 

Northern 

harrier 

Lazuli 

bunting 

Chipping 

sparrow 

Swainson’s 

thrush 

Willow 

flycatcher 

Northern redlegged frog Coho salmon 

Oregon 

vesper 

sparrow 

Oregon white 

oak 

Oregon white 

oak 

Red-eyed 

vireo 

Yellowbreasted chat Oregon chub Oregon chub 

Peacock 

larkspur 

Slender-billed 

whitebreasted 

nuthatch 

Purple finch Western 

purple martin 

Yellow 

warbler Painted turtle Pacific lamprey 

Savannah 

sparrow 

Taylor's 

checkerspot 

butterfly 

Slender-billed 

whitebreasted 

nuthatch 

Wood duck Pintail Red-legged 

frog 

Short-eared 

owl 

Western 

bluebird 

Western grey 

squirrel 

Yellow 

Warbler 

American 

bittern 

Steelhead 

trout 

Streaked 

horned lark 

Western 

scrub jay 

Western 

wood pewee Cinnamon teal 

Western 

brook 

lamprey 

Western 

meadowlark Lesser yellowlegs 

American 

beaver 

Willamette 

valley daisy Mallard Bald eagle 

White rock 

larkspur Ring-necked duck 

 Sora 

Conservation Target Selection Criteria 

The Conservation target selection criteria were developed based on published species selection 

criteria (Altman 2001, Altman 2010, Altman and Stephens 2012, USFWS 2012) and management 

considerations (Altman 2010, USFWS 2012). The criteria were reviewed by biologists and scientists 

familiar with Willamette Valley species and habitats. Comments received were incorporated into the 

final criteria which are presented below.

Initial Screen 

1. The species represents a larger group of species, in that, when conservation actions are 

directed toward the single species, the actions will also benefit the larger group of species. 
Willamette Valley Conservation Study 

Appendix D. Selection Criteria D-3 

Ecological Criteria 

2. The species is strongly associated with a particular habitat type, or specific attribute or 

condition within that habitat type. 

3. The species has large spatial needs that can encompass the needs of other species. 

4. The species’ population dynamics track changes in the larger landscape or ecosystem. 

5. Climate change risks to the species are similar in nature and risk level to those of the larger 

group of species represented. 

6. Invasive species, pests, and pathogen risks to the species are similar in nature and risk level 

to those of the larger group of species represented. 

Management Criteria 

7. The species can be readily monitored using standard techniques that track progress toward 

meeting population objectives. 

8. Sufficient data exist to model the species habitat relationships and population viability (e.g., 

habitat suitability, occurrence probability, reproduction, recruitment, and survivorship). 

9. The species has public interest or appeal. 

Conservation Status 

10. The species has special conservation status (e.g. ODFW OCS Strategy Species; Federal ESA; 

Oregon State ESA; Birds of Conservation Concern [USFWS 2008b] Birds of Management 

Concern [USFWS 2011b], NWRS strategic growth policy [USFWS 2013d]). 

The first criterion was used as an initial screen. If, for an obvious reason, a species was poor at 

representing the habitat and the larger group of species using that habitat, then it was not scored. 

The ecological criteria relate to the species’ need for particular habitats and spatial requirements, and 

whether its population dynamics track changes within those habitats, and how climate change and 

other future threats might affect the species relative to the larger group the species represents. From a 

management perspective, we included criteria related to the ease of monitoring, the sufficiency of 

data to establish population objectives and allow for GIS modeling, and social acceptance of the 

species. 

The conservation status of the species (ODFW 2006, ORBIC 2010) was to be used as a tie-breaker, 

should applying the selection criteria result in species being ranked equally, but this was never the 

case. 

Evaluation Criteria 

In order to provide common and consistent means by which biologists and species experts could rate 

a species ability to represent a habitat and its associated species, we developed evaluation criteria as 

the basis for scoring each species. The evaluation criteria are provided below. 

Initial Screen 

1. A species represents a larger group of species, in that, when conservation actions are directed 

toward the single species, the actions benefit a group of species, i.e., good indicator species. 
Willamette Valley Conservation Study 

D-4 Appendix D. Selection Criteria 

 Yes = The species is a habitat specialist with life history requirements that encompass the 

needs of many native species associated with that habitat. 

 No = The species’ habitat requirements are too specialized or too general to represent a 

large group of native species. 

Ecological Criteria 

2. The species is strongly associated with a particular habitat type. 

 High = The species reaches highest population densities, or greatest recruitment occurs, 

within a particular habitat type. 

 Medium = The species’ population densities or recruitment are similar across a few native 

habitat types. 

 Low = The species is a habitat generalist, not strongly associated with a particular habitat 

type. 

Because our goal is self-sustaining populations, we were most concerned with identifying the habitat 

in which recruitment is highest, not necessarily where densities are greatest as the two are not 

necessarily linked (Van Horne 1983). 

3. The species has large spatial needs that encompass the needs of other species. 

 High = A single self-sustaining population of the species requires a large land base. 

 Medium = A single self-sustaining population of the species requires a moderate land 

base. 

 Low = A single self-sustaining population of the species requires a small land area. 

4. The species’ population dynamics track changes in the larger landscape or ecosystem. 

 High = Improvements in population dynamics (reproduction, recruitment, and 

survivorship) can be directly linked to improvements in the habitat type. 

 Medium = Population dynamics are moderately linked to improvements in the habitat 

type, or nonhabitat factors (e.g., intraspecific competition) equally important to 

population dynamics. 

 Low = Generalist species whose population dynamics are not linked to changes in a 

particular habitat type or nonhabitat factors govern population dynamics (e.g., 

predator/prey relationship). 

5. Climate change risks to this species are similar in nature and risk level to those of the larger 

group of species represented. 

 Yes = The species response to climate change is expected to be similar to the larger 

community the species represents. 

 No = The species has life history requirements or inherent capabilities (dispersal, food 

base) that either make the species more or less susceptible to the effects of climate 

change than that of the larger group the species represents. 

6. Invasive species, pests, and pathogen risks to this species are similar in nature and risk level 

to those of the larger group of species represented. 

 Yes = The species faces threats posed by invasive species, pests, or pathogens also facing 

the larger community the species represents. 
Willamette Valley Conservation Study 

Appendix D. Selection Criteria D-5 

 No = The species faces unique risks related to invasive species, pests, or pathogens not 

facing the larger community the species represents (such as amphibians and chyrtid 

fungus or bats and white-nose syndrome). 

Management Criteria 

7. The species can be readily monitored using standard techniques that track progress toward 

meeting population objectives 

 Yes = The species can be readily monitored using standard techniques that are 

economical, and do not require specialized equipment. 

 No =The species is difficult or costly to monitor and/or requires specialized equipment. 

8. Sufficient data about the species exist (e.g., population objectives, habitat suitability, 

occurrence probability, reproduction, recruitment, survivorship). 

 High = The species’ population objectives have been set locally or local data exists to 

establish them. Habitat, occurrence, and demographic data exist based on local research. 

 Medium = The species’ population objectives must be stepped down from national plans. 

Habitat, occurrence, and demographic data exist, but are based on research conducted 

elsewhere. 

 Low = The species population objectives, habitat occurrence, or demographic data are 

lacking. 

9. Does the species have public interest, and/or appeal? 

 Yes = The species is of interest and supported by the general public. 

 No = The species is not on the public’s radar or has negative public connotations. 

Species Status 

10. The species has special conservation status. 

 High = The species is listed, proposed for listing, or a candidate of conservation concern 

under the Federal or State Endangered Species Act. 

 Medium = The species is listed as a Bird of Conservation Concern in Bird Conservation 

Region 5. Declining population trends or local extirpations exist. The species has an 

initial listing status (Birds of Management Concern, OCS Strategy Species, OR State 

Sensitive, OR State Vulnerable, etc.). 

 Low = The species has no special status. 

Applying the Criteria 

Some criteria were split into categories that could be rated as high, medium, or low. Other criteria 

could be answered with a yes or no. Points were assigned to each categorized criteria based on 

whether it is rated high (1 point), medium (0.5 points), or low (0 points). Points were assigned to 

each yes/no criteria based on whether the answer is yes (1 point) or no (0 points). Biologists and 

scientists were asked not to score a species if they were unfamiliar with it. 

A spreadsheet was developed that allowed importance weights to be assigned within the selection 

criteria categories (ecological and management) as well as assigning importance weights to the 

categories themselves (ecological criteria could be weighted over management criteria or vice versa). 

An initial weighting was proposed that weighted ecological criteria 2:1 over management criteria 
Willamette Valley Conservation Study 

D-6 Appendix D. Selection Criteria 

because we wanted to avoid selecting a species that is weak in representing a larger group of species 

using the same habitat, but was good at meeting management criteria. This weighting scheme was 

approved by the biologists and was used in determining total scores for each species. 

Within the ecological criteria, we weighted habitat association and spatial needs criteria over the 

climate change and invasive species criteria because the science is more certain on the former two 

than the potential future response to climate change and other threats. For the management criteria, 

we weighted monitoring and data availability criteria over the public interest/appeal criterion because 

the latter criterion required us to estimate public attitudes. 

Scores from each biologist and research scientist were combined in a master list. The list was sent 

back to the group to review for logic and consistency. We then selected one or more species to 

represent each habitat type based on the scoring. 

Results 

Species selected to represent each habitat type are provided in Table D2. 

Table D2. Species Selected to Represent Habitats 

Species Habitat 

Western meadowlark and Oregon vesper sparrow Prairie 

Western bluebird Oak savanna 

Slender-billed white-breasted nuthatch Oak woodland 

Yellow warbler Riparian forest 

Yellow-breasted chat Riparian shrublands 

Willow flycatcher was initially selected to represent riparian shrublands, but data anomalies 

associated with the Breeding Bird Survey made calculating a Willamette Valley population in 

riparian shrublands problematic. For that reason, and because their habitat requirements are very 

similar, yellow-breasted chat was selected to represent riparian shrublands. The Northern red-legged 

frog was initially selected to represent wetlands, and Chinook salmon were initially selected to 

represent riverine systems. Data gaps made developing rational population objectives problematic for 

those species in the Willamette Valley; therefore, we decided to focus on the habitat itself. For that 

reason, those species were not carried through the SHC analysis. Final scores for each species/habitat 

combination are provided in Table D3.

Western meadowlark/USFWS Western bluebird/USFWS
Table D3. Final Scores for all Species/Habitat Combinations 

Prairie Oak Savanna Oak Woodland Riparian Forest Riparian Shrubland Wetlands Riverine Species Score Species Score Species Score Species Score Species Score Species Score Species Score Western meadowlark 0.88 Western bluebird 0.82 Slender-billed whitebreasted nuthatch 0.85 Yellow Warbler 0.69 Willow flycatcher 0.75 Northern red-legged frog 0.80 Chinook salmon 0.90 Northern harrier 0.60 

Slender-billed whitebreasted 

nuthatch 

0.75 Oregon white oak 0.77 Swainson’s thrush 0.63 Yellow warbler 0.74 Great blue heron 0.64 Coastal cutthroat trout 0.87 

Bradshaw's lomatium 0.56 Oregon white oak 0.73 Acorn woodpecker 0.75 Downy woodpecker 0.61 Yellow- breasted chat 0.65 Painted turtle 0.61 Coho slamon 0.71 Streaked horned lark 0.56 Lazuli bunting 0.62 Chipping sparrow 0.63 California myotis 0.57 Northern red-legged frog 0.62 Cinnamon teal 0.61 Steelhead trout 0.71 Willamette valley daisy 0.53 Kincaid's lupine 0.56 Band-tailed pigeon 0.58 Western purple martin 0.57 Common yellowthroat 0.52 Pintail 0.59 Bull trout 0.70 Nelson's checkermallow 0.52 American kestrel 0.53 Western wood pewee 0.57 Wood duck 0.55 Swainson's thrush 0.50 Mallard 0.57 Western brook lamprey 0.66 Golden paintbrush 0.49 Western scrub jay 0.47 Black-capped chickadee 0.53 Red-eyed vireo 0.49 Dusky Canada goose 0.56 Pacific lamprey 0.66 Oregon vesper sparrow 

0.49 Fender's blue butterfly 0.46 Purple finch 0.50 Brown creeper 0.44 Oregon chub 0.55 American beaver 0.62 

Savannah sparrow 

0.49 Taylor's checkerspot 0.23 Western grey squirrel 0.49 Greater yellowlegs 0.55 Bald eagle 0.62 

White rock larkspur 0.45 Sora 0.53 

Redlegged frog 

0.59 

Peacock larkspur 0.44 American bittern 0.49 Oregon chub 0.49 Short-eared owl 0.44 Dunlin 0.48 

______________________________________________________________________________________________ Willamette Valley Conservation Study

Appendix D. Selection Criteria

______________________________________________________________________________________________

D-7
Willamette Valley Conservation Study 

D-8 Appendix D. Selection Criteria 

This document continues on the next page. 
Willamette Valley Conservation Study 

Appendix E. Population and Habitat Objectives E-1 

Appendix E. Population and Habitat Objectives 

Population Objectives 

Population objectives represent a measurable expression of a desired outcome. They are expressed as 

abundance, trend, vital rate, or other measurable indices of population status, based on the best 

biological information about what constitutes a healthy, self-sustaining population (NEAT 2006). 

The objectives serve as the basis for estimating how much habitat to maintain based on the current 

state of knowledge related to habitat suitability, territory size, population viability, and probability of 

occurrence or average density in suitable habitat (USFWS 2008a). 

To set population objectives we assembled panels of research scientists and biologists with expertise 

in each of our conservation target species, and asked them—what would a reasonable population 

objective be, that when realized, would indicate that our goal of a landscape capable of supporting 

healthy, self-sustaining populations had been achieved? We also explored the most important factors 

limiting the populations of our conservation targets to ensure that those factors were addressed. 

Population objectives have already been established for some of our conservation targets in 

documents such as endangered species recovery plans. We discussed those objectives with our expert 

panels and updated them if new information warranted a change. For species without published 

objectives, we considered population status and trends, as described below, in developing population 

objectives. 

Landbirds 

The Partners In Flight (PIF) North American Landbird Conservation Plan (Rich et al. 2004), which 

was ratified by Canada, Mexico, and the United States, established population objectives for 

landbirds on a continental scale, but they were not stepped-down to any local scale. To do so, we 

worked closely with our expert panels which included ODFW, the American Bird Conservancy, the 

Pacific Coast Joint Venture, Fish and Wildlife Service biologists, and others to step-down those 

continental objectives to the Willamette Valley. 

A major challenge in establishing population objectives is to decide on an abundance that would be 

sufficient to meet the goals for each species. With an overall goal of a landscape capable of 

supporting healthy, self-sustaining populations, at the very least, the objectives should be sufficient 

to reduce the risk of extirpation to a very low level. But landbirds provide valuable economic benefits 

and ecological services that must also be considered. For example, birds provide pest control services 

by feeding on insects and rodents that harm agricultural crops, they pollinate plants and disperse 

seeds, and they provide recreational opportunities enjoyed by thousands of the valley’s residents, 

whose spending on bird watching and other recreation supports local communities and aids their 

economic development (Whelan et al. 2008, Carver and Caudill 2013). 

A recent study of the demographics and economic impacts of birding based on the 2011 National 

Survey of Fishing, Hunting, and Wildlife-Associated Recreation (USFWS and USDI 2011) estimated 

that 892,000 Oregonians, or about 23 percent of the state’s population, participated in bird watching 

activities. On a national scale, the 46.7 million birders spent about $41 billion on trips and 

equipment, creating 666,000 jobs and generating $31 billion in employment income and $13 billion 

in local, state, and federal tax revenue. With this magnitude of positive benefits, the question then 
Willamette Valley Conservation Study 

E-2 Appendix E. Population and Habitat Objectives 

becomes, what population level would be sufficient to allow these species to not only maintain their 

populations in the valley, but facilitate their provision of economic benefits and ecological services? 

To address this question, Partners in Flight proposes a “minimum acceptable abundance” objective 

by considering three additional questions: How few birds are we willing to accept given their many 

benefits? How many birds can we afford given the competing demands for the land? And, how will 

future generations judge the decisions we make today? 

ODFW developed a similar type of objective for the Upper Willamette River Conservation and 

Recovery Plan for Chinook Salmon and Steelhead (ODFW and NMFS 2011). That plan has two 

goals. The first is to achieve delisting objectives. But beyond achieving minimum population levels 

to allow delisting, ODFW proposes a “broad sense recovery” objective which they define as 

“Oregon populations of naturally produced salmon and steelhead that maintain a self-sustaining 

SMU (Species Management Unit) while providing significant ecological, cultural, and economic 

benefits.” 

We agree that a population objective, once achieved, should result in healthy, genetically diverse 

populations that are well distributed across their historic range and capable of providing recreational 

opportunities, economic benefits, and ecological services. An objective that achieves that would align 

well with ODFW’s goal for the Oregon Conservation Strategy (OCS), which is to “maintain healthy 

fish and wildlife populations by maintaining and restoring functioning habitats, prevent declines in 

at risk species, and reverse any declines in these resources where possible” (ODFW 2006). 

Setting population objectives requires knowledge of the current population size and trend, as well as 

information on historic baselines to which current populations can be compared (Rich et al. 2004). 

For example, the 1986 North American Waterfowl Management Plan adopted by the United States 

and Canada used the abundance of waterfowl in North America during the 1970s, their trends since 

that time, and the traditional distribution of waterfowl during their various life-cycle periods, as the 

baseline for establishing population objectives (NAWMPPC 2004). The 1970s populations were 

considered to be at levels that not only sustained waterfowl on the landscape, but provided valuable 

recreational opportunities which supported local communities and their economies. By concentrating 

conservation efforts to achieve the 1986 plan objectives, the 2012 update noted that many waterfowl 

populations are now substantially larger than they were at the time the original plan was adopted 

(NAWMPPC 2012). 

The North American Landbird Conservation Plan followed a similar approach, adopting a continental 

goal of restoring landbird population levels to the late 1960s population levels, which are believed to 

be achievable and realistic for most species (Rich et al. 2004). Adopting a late 1960s baseline 

population goal accepts the obvious fact that the competing demands on the land means that the 

extensive loss of native habitats that occurred since European settlement will not be reversed to any 

significant level, but would restore populations to levels capable of providing greater economic 

benefits and ecological services. The late 1960s also coincides with the beginning of the Breeding 

Bird Survey (BBS) across North America, which provides the only consistent data upon which to 

base measureable population objectives. 

With an overall goal of returning landbird population levels to that of the late 1960s as the baseline 

for establishing population objectives, PIF established four population objective categories which 

call for: 1) doubling the populations of species suffering severe population declines; 2) a 50 percent 

increase for species that have undergone moderate declines; 3) maintain or increase populations for 
Willamette Valley Conservation Study 

Appendix E. Population and Habitat Objectives E-3 

species with uncertain or unknown past trends; and 4) maintain populations of species with stable or 

increasing populations. 

For the landbird conservation target species, we set long-term (approximately 50-year) aspirational 

goals and stepped those down to short-term (10 to 20 year) actionable objectives. As discussed, we 

considered both the current population size and the long-term population trend in setting population 

objectives. In doing so it became evident that our conservation target species fell into two broad 

categories: those currently with very small and disjunct populations, most of which have suffered 

steep, long-term declines; and those with larger, though still relatively small populations, most of 

which have experienced less dramatic declines. 

The first situation applies to the valley’s grassland, oak savanna, and riparian shrubland species 

(western meadowlark, Oregon vesper sparrow, western bluebird, and yellow-breasted chat). For these 

species, documented population declines and range contractions support a conclusion that the current 

network of suitable habitat patches being managed for these species does not meet their minimum 

requirements in terms of the number, size, and distribution across the landscape to ensure their longterm persistence. Species with somewhat larger populations and less clear population trends are those 

that represent the oak woodlands and riparian forests (slender-billed white-breasted nuthatch and 

yellow warbler). 

Since population size is a major determinant of extinction risk (Soulé 1986, Traill et al. 2007, Reed et 

al. 2003, Groom et al. 2006) and species with very small and disjunct populations are at the greatest 

risk of extirpation, we wanted the objective for the first group to be at an achievable abundance that 

would infer a low probability of extirpation, or conversely, a high probability of viability over the 

long run. We explored applying the PIF standard of doubling the population of species suffering 

severe population declines, but concluded that a mere doubling of current, extremely low populations 

would still leave these species vulnerable to extirpation in the valley. Our expert panel suggested we 

consider what a minimum viable population (MVP) would be for these species. An MVP is defined 

as the smallest population size (abundance) required for a species to have a predetermined 

probability of persistence for a given length of time (Shaffer 1981, Reed et al. 2003). For example, an 

Streaked horned lark/David Maloney, USFWS 
Willamette Valley Conservation Study 

E-4 Appendix E. Population and Habitat Objectives 

MVP could be set at the minimum number of individuals necessary for a population to have a 95 

percent probability of persisting for 100 years, or a 90 percent chance of persisting for 30 

generations. 

MVPs are determined by conducting a Population Viability Analysis (PVA). A PVA models the 

combined effects of demographic, environmental, and genetic stochasticity, along with deterministic 

factors such as habitat loss, in calculating the lowest population abundance necessary for a species to 

persist over a desired time period (Akҫakaya 2000). But because species-specific data are rarely 

available to complete such in-depth analysis (as is the case for the valley species), two meta-analyses 

of PVAs were reviewed to determine if a generalized MVP abundance standard could be supported 

by the published PVAs. A meta-analysis analyzes results from different studies to identify patterns 

among study results or other relationships that emerge in the context of multiple studies. 

In a meta-analysis covering PVAs for 212 species, and implementing a standardization process to 

make reported MVPs comparable, Traill et al. (2007) was able to derive a cross-species frequency 

distribution of MVPs with a median of 4,169 individuals (95% CI = 3,577-5,129) and suggested that 

in lieu of species-specific data, to ensure the long-term persistence of a population, practitioners 

should “manage for biologically relevant MVPs [of] at least 5,000 adult individuals whilst 

addressing the concomitant mechanisms of decline.” 

Reed et al. (2003) completed a meta-analysis of PVAs generated for 102 vertebrate species based on 

actual life-history data. They determined mean and median estimates of MVPs at 7,316 and 5,816 

adults, respectively. The 102 vertebrates modeled included 2 amphibians, 28 birds, 1 fish, 53 

mammals, and 18 reptiles. They found no significant difference in MVP due to global latitude, 

taxonomic grouping, or trophic level. Reed et al. (2003) concluded that “in order to ensure the longterm persistence of vertebrate populations, sufficient habitat must be conserved to allow for 

approximately 7,000 breeding age adults.” 

But such generalizations regarding MVPs are subject to 

criticism. Flather et al. (2011) argues that extinction 

risks are “often context dependent and manifest from a 

complex interaction between life-history, environmental 

context and threat.” They contend that “MVP estimates 

both among and within species show striking variation 

for many reasons. The fundamentally contingent nature 

of MVPs means that we cannot support a universally 

applicable MVP threshold.” 

With that caveat in mind, and in lieu of PVAs for the 

species in question, we adopted an interim long-term 

(~50-year) population goal of 6,000 individuals, the 

median MVP abundance as determined by the two metaanalyses of PVA models. An aspirational goal of 6,000 

individuals for western meadowlark, western bluebird, 

Oregon vesper sparrow, and yellow-breasted chat is an 

achievable abundance for the valley that would infer 

viability over the long-run. 

We took a different approach for the two species with 

Western meadowlark/USFWS somewhat larger populations: yellow warbler and white-
Willamette Valley Conservation Study 

Appendix E. Population and Habitat Objectives E-5 

breasted nuthatch. Because of the uncertainties of the BBS trend analyses (both have nonsignificant 

trends with wide 95 percent confidence intervals) contrasted against the certainties and documented 

loss of the priority habitat types these species were chosen to represent (riparian forest and oak 

woodlands), we adopted the PIF goal of a 50 percent population increase for both species. Adopting 

this goal recognizes the trade-off of basing objectives using nonsignificant BBS trends amid 

contrasting documented declines in the primary habitat type for these species. A 50 percent increase 

over 50 years equates to a growth rate of just 0.8 percent per year, a slow growth rate, but one that 

would maintain and slowly rebuild populations and habitats over time, benefiting not just the 

conservation target species, but the other wildlife species they were chosen to represent. 

To determine the shorter-term (10 to 20 years) actionable objectives, we calculated the annual growth 

rate needed for each of these species to achieve the aspirational population goal over the course of 50 

years and applied that rate to the first 10 years. For example, to increase the population of western 

meadowlarks from their current population of approximately 1,200 to 6,000 over a 50-year period, 

would require an annual growth rate (λ) of 1.0327 (1,200 * 1.032750 = 5,996). Applying this rate for 

10 years yields a 10-year population objective of 1,656 (1,200 * 1.032710 = 1,656). 

Current population estimates came from two sources. Estimates for the rare and imperiled species 

(western meadowlark, Oregon vesper sparrow, western bluebird, and yellow-breasted chat) were 

developed by the American Bird Conservancy and Pacific Coast Joint Venture, based on multiple 

surveys and censuses conducted in the valley. 

Estimates for the more abundant species (slender-billed white-breasted nuthatch and yellow warbler) 

were developed by using recent BBS point count data (2003-2013). The methodology for using BBS 

data is explained in two documents—the Guide to the PIF Population Estimates Database (Blancher 

et al. 2007) and The Handbook to the Partners in Flight population Estimates Database, Version 2.0 

(Blancher et al. 2013). 

Bird trend data comes from the Patuxent Wildlife Research Center (Sauer et al. 2008). Trends 

specific to the Willamette Lowlands are available from the initiation of the BBS in the valley in 1968 

until 2007. Beyond 2007, trends were calculated only for entire Bird Conservation Regions (BCRs) 

making identification of trends specific to the valley far less certain. 

Since we are establishing ecoregional population objectives, we recognized the need to account for 

individuals outside the designated core habitat patches when setting the objectives. To do this we 

assumed an equal number of birds could be distributed throughout the ecoregion outside the core 

habitat patches once established. This assumption must be tested through assumption-based research 

and the objectives modified based on the 

results of that research. 

Listed Prairie Species 

Population objectives for prairie species in 

the valley that were listed under the ESA 

prior to 2010 are published in the Recovery 

Plan for the Prairie Species of Western 

Oregon and Southwestern Washington 

Taylor’s checkerspot butterfly/ 

Ted Thomas, USFWS 
Willamette Valley Conservation Study 

E-6 Appendix E. Population and Habitat Objectives 

(USFWS 2010a). These objectives are expressed in terms of population abundance, trend, and 

distribution across recovery zones that encompass the study area. The WVCS planning team met 

with the Recovery Plan authors and others engaged in recovery actions in the valley to determine if 

the population objectives remain valid. There was general agreement that the objectives remain valid, 

and those objectives were adopted for this study. Some minor changes were adopted for some of the 

conservation target species based on new information derived from field monitoring since the 

Recovery Plan was published in 2010. Suggested changes were adopted and are explained in the 

discussion of the affected species. 

Population objectives for the two recently listed species (streaked horned lark and Taylor’s 

checkerspot butterfly) have not been developed. Recovery plans will be developed for these species 

in the future. In the interim, we developed population objectives, which will be revised as appropriate 

once recovery plans are published. As described below, population objectives for Taylor’s 

checkerspot were fashioned after the population objectives developed for Fender’s blue butterfly, 

based on historical distribution in the valley and the metapopulation dynamics exhibited by Fender’s 

blue butterfly. 

Habitat Objectives 

Habitat objectives describe the area, quality, and distribution of habitat across a landscape thought to 

be necessary to achieve population objectives (NEAT 2006). 

Migratory Landbirds 

More than 15 years ago, Altman (1999) proposed a a landbird conservation strategy of protecting, 

restoring, and managing additional suitable habitat in proximity to existing population centers, 

providing habitat for dispersers to establish new subpopulations on newly restored habitat. ODFW 

(2010) suggested that these stabilized population centers could be the source of dispersers to expand 

the population elsewhere in the valley. This strategy, focusing efforts where the few remaining 

subpopulations occur, and radiating out from them, influenced the development of the population and 

habitat objectives. 

ODFW (2006) identified the factors that are limiting populations of many of the targeted species. 

Two important factors are limiting populations of grassland birds in the Willamette Valley. The first 

is the loss of grassland habitats and the 

degradation of remaining habitat due to 

invasive species and the lack of fire, 

resulting in small, disjunct populations. The 

second was nesting failure due to the timing 

of land management practices (mowing, 

haying, spraying) occurring during critical 

nesting times (mid-April to mid-July) for 

these ground-nesting species. 

For the yellow-breasted chat, ODFW 

(2006) identified the loss of large patches of 

riparian shrub habitat as an important 

limiting factor. For the two cavity-nesting 

species—western bluebird and slenderWestern bluebirds/Georg billed white-breasted nuthatch, habitat loss e Gentry, USFWS
Willamette Valley Conservation Study 

Appendix E. Population and Habitat Objectives E-7 

and degradation along with fewer mature oaks with cavities and competition for those nesting sites as 

factors limiting their populations. 

The expert panels summarized these factors as an insufficient number of core habitat patches—an 

insufficient number, size, and distribution of suitable habitat being managed free of other 

management conflicts to support healthy populations across each species historic range in the valley. 

A core habitat is an area of suitable habitat and of sufficient size that contains the properties and 

elements required for successful reproduction and survival of the targeted species. Within these core 

habitats, wildlife management would be prioritized over other management concerns. These core 

habitat areas would provide safe and secure breeding grounds to allow small, disjunct populations the 

space and time needed to begin to recover and to eventually become the source of dispersing 

individuals looking to establish new subpopulations We attempted to address this lack of core habitat 

areas by developing objectives for networks of suitable habitats to be distributed across the valley. 

In areas with highly fragmented habitats such as the Willamette Valley, the lack of source 

populations can result from the combination of small, disjunct populations coupled with nesting 

failures where they do attempt to nest (Altman 1999, ODFW 2010). A source population is a 

population that produces more offspring than is necessary to maintain a stable population size, so the 

“surplus” individuals disperse to other areas establishing new or augmenting other extent 

subpopulations (Pashley et al. 2000). Where source populations potentially exist (such as the western 

meadowlark populations at W.L. Finley and Baskett Slough National Wildlife Refuges), a lack of 

suitable habitat for the dispersers to establish new territories in areas with a high probability of nest 

success, limits the ability of these source populations to contribute to population recovery. 

To support the current and/or historic distribution of habitat and species distribution, and maintain 

multiple populations that are geographically spaced to enhance the likelihood of regional population 

persistence, we developed guidance on how the network should be distributed within the ecoregion. 

Therefore, the number and distribution of core habitat patches was uniquely determined for each 

species to reflect the variability of each species ecology, population size, area requirements, and 

patterns of historic and current habitat distribution and fragmentation, relative to latitudinal divisions 

(north to south) and also by Level IV ecoregions (Omernik 1987). The objective of a minimum 

number of core habitats distributed across the northern, central, and southern portions of the valley 

reflects the current and historic distribution of the priority habitats in the valley. For example, within 

the Willamette Valley, prairie habitat was historically and is currently unequally distributed south to 

north, so we adjusted the distribution of core habitats accordingly. 

We distributed core habitats across three zones: north (north of Salem), central (Salem to Corvallis), 

and south (south of Corvallis); and also by Level IV ecoregions (Omernik 1987). The four Level IV 

ecoregions are the Portland/Vancouver Basin, Willamette River and Tributaries Gallery Forest, 

Prairie Terraces, and Valley Foothills. 

The use of variable sized core habitat patches reflects the local realities of habitat availability and 

land ownership within the Willamette Valley. While the population objectives could theoretically be 

achieved with only a few large core habitat patches, the fewer number of patches would necessarily 

be more isolated from one another and other potentially suitable habitat patches, which would 

compromise their functionality as source populations. A greater number of core habitat patches 

distributed across the historic range of the species would better fulfill this critically important role. 

The distribution of core habitat patches within the ecoregion was based on knowledge of each species 

historic patterns of distribution and an assessment of current occupancy. 
Willamette Valley Conservation Study 

E-8 Appendix E. Population and Habitat Objectives 

To determine the amount of habitat needed to meet landbird population objectives, we used the 

largest and densest known subpopulations of each species in the valley as the reference from which 

to establish area requirements. These subpopulations typically occurred on large, single ownership 

parcels with high quality habitat. As most of the landscape outside these ownerships is fragmented 

and of lower quality, we assumed that more area would be required to support an equal number of 

breeding pairs outside of these ownerships and increased the amount of area needed from the highest 

density examples by 50 percent to establish core patch size objectives. The fact that territory size 

varies with habitat quality is well established (O’Connor et al. 1999) and has been demonstrated 

empirically in the valley for grassland birds (Altman 1999, Altman et al. 2011). For species without 

reference subpopulations we used breeding territory sizes reported in the literature, and increased that 

size by 50 percent for the reasons given above. 

Assumptions/Rationale 

Assumptions used in determining population and habitat objectives for each of the targeted landbird 

species are provided below. 

Western Meadowlark 

The population estimate is based on data from ODFW (2010), 

Altman et al. (2011), and observations from extensive 

reconnaissance throughout the Willamette Valley. For the 

purpose of calculating a population estimate, a breeding 

season male detection was considered a pair. We also 

assumed that there was a second female for 25 percent of the 

males. 

The North American Breeding Bird Survey (BBS) reports a 

statistically significant declining population trend of -10.0 

percent per year (95% confidence interval [CI] -19.4 to -0.6) 

from 1966-2007, the latest year trends were calculated for the 

Willamette Lowlands (Sauer et al. 2008). This equates to an overall population decline of over 98 

percent, the highest rate of decline among all grassland bird species in the valley. 

The habitat objective for the area needed per core habitat patch is based on the documented territory 

size of the western meadowlark at Baskett Slough NWR and at the Willamette Floodplain Research 

Natural Area at the W.L. Finley NWR. Baskett Slough NWR supports 15-20 territories on 

approximately 500 acres of mixed quality upland prairie and agricultural fields. W.L. Finley NWR 

supports 25-35 territories on approximately 600 acres of mostly highly suitable wet prairie habitat 

(Altman et al. 2011). Thus, we assumed 20 territories per 500 acres and increased that size by 50 

percent to correct for habitat quality outside these reference populations. 

Based on habitat characteristics and western meadowlark breeding requirements, a single large 

subpopulation of 30-40 breeding pairs would require a habitat patch of about 1,313 acres. A mediumsized subpopulation of 20-30 breeding pairs would require a habitat patch of about 938 acres, and a 

small subpopulation of 10-20 breeding pairs would require a 563-acre habitat patch. 

Oregon Vesper Sparrow 

The population estimate for Oregon vesper sparrow is from Altman (2016) based on. For the purpose 

of calculating a population estimate, a singing male is considered a pair. From 1968 to 2007, the BBS 

Western meadowlark/© John and 

Karen Hollingsworth 
Willamette Valley Conservation Study 

Appendix E. Population and Habitat Objectives E-9 

reports a statistically significant declining population trend of -8.6 percent per year (95% CI -32.4 to 

15.2) (Sauer et al. 2008). This equates to an overall population decline of 97.5 percent. 

The objective for area needed for a core habitat patch is based on populations at Bald Hill Farm and 

the Oregon State University Beef Ranch, both near Corvallis. These areas support 10 and 12 pairs 

respectively, on pastureland, the habitat type with the highest densities in the Willamette Valley. 

There are approximately 10 pairs on 200 acres at Bald Hill Farm and 12 pairs on 200 acres at the 

OSU Beef Ranch. Thus, we assumed 11 pairs per 200 acres, and after correcting for habitat quality, 

assumed 11 pairs per 300 acres. 

Based on the existing population size, territory size, and habitat suitability and availability, a single 

large subpopulation of >15 pairs would require a habitat patch of about 477 acres. A medium-sized 

subpopulation of 10-15 pairs would require a habitat patch of about 341 acres. A small subpopulation 

of 5-10 breeding pairs would require a 205-acre habitat patch. 

Western Bluebird 

The population estimate for western bluebird is derived from the past 10 years (2003-2012) of 

Breeding Bird Survey relative abundance data specific to the Willamette Valley, following the 

process described by Blancher et al. (2013) and corrected for BBS survey habitat representation and 

nontarget habitat biases. 

Breeding bird survey results specific to the Willamette Valley are not available, so we relied on BBS 

trend calculated for the Southern Pacific Rainforest Region (i.e., western Washington and Oregon, 

and northern California). The reported trend for that region is -1.2 percent per year. As the Southern 

Pacific Rainforest Region includes areas far less impacted than the Willamette Valley, we estimate 

that the reported trend underestimates the decline in the Willamette Valley by an unknown degree. 

Western bluebirds defend a relatively small breeding territory, ranging from one to several acres 

(Csuti et al. 2001). For this analysis, we used a conservative breeding territory of five acres. The area 

needed for a core habitat patch is based on increasing this approximate territory size by 50 percent in 

lieu of a reference high density population. 

Based on territory size, and habitat suitability and availability, a single large subpopulation of 30-40 

pairs would require a habitat patch of about 263 acres. A medium-sized subpopulation of 20-30 pairs 

would require a habitat patch of about 188 acres. A small subpopulation of 10-20 breeding pairs 

would require about a 113-acre habitat patch. 

Slender-billed White-breasted Nuthatch 

The population estimate for slender-billed white-breasted nuthatch is derived from the past 10 years 

(2003-2012) of Breeding Bird Surveys’ relative abundance data specific to the Willamette Valley, 

following the process described by Blancher et al. (2013) and corrected for BBB survey habitat 

representation and nontarget habitat biases. 

From 1968-2007, the BBS reports a nonstatistically significant population trend in the Willamette 

Lowlands of -3.0 percent per year, (95% CI -22.5 to 16.5) (Sauer et al. 2008). 

The slender-billed white-breasted nuthatch defends territories of various sizes ranging from a few 

acres to nearly 100 acres depending on habitat conditions (Csuti et al. 2001). For this analysis, we 

used a conservative home-range figure of 10 acres. The area needed for a core habitat patch is based 
Willamette Valley Conservation Study 

E-10 Appendix E. Population and Habitat Objectives 

on increasing this approximate territory size by 50 percent in lieu of a reference high density 

population. 

Based on habitat characteristics and breeding requirements, a large subpopulation consisting of 50 

pairs or more, would require about a 900-acre habitat patch. A medium subpopulation of 30-50 pairs 

would require about a 600-acre patch, and a small population of 10-30 pairs would require about 300 

acres. 

Yellow Warbler 

The population estimate for the yellow warbler is derived from the past 10 years (2003-2012) of 

Breeding Bird Survey (BBS) relative abundance data specific to the Willamette Valley following the 

process described by Blancher et al. (2013) and corrected for BBS habitat representation and 

nontarget habitat biases. 

The BBS reports a nonstatistically significant population trend for the Willamette Lowlands of +2.5 

percent per year from 1968-2007 (95% CI -16.9 to 21.9) (Sauer et al. 2008). 

Yellow warblers defend territories of various sizes ranging from a few acres to nearly 100 acres 

depending on habitat (Csuti et al. 2001). For this analysis, we used a conservative home-range figure 

of three acres. The area needed for a core habitat patch is based on increasing this approximate 

territory size by 50 percent in lieu of a reference high density population. 

Based on habitat characteristics and breeding requirements, a large subpopulation consisting of 100-

140 pairs would require about a 540-acre habitat patch. A medium subpopulation of 60-100 pairs 

would require about a 360-acre patch, and a small population of 20-60 pairs would require about 180 

acres. 

Yellow-breasted Chat 

The population estimate for yellow-breasted chat is from the American Bird Conservancy based on 

available data from multiple riparian bird surveys, anecdotal observations, and professional 

knowledge. 

From 1968-2007, the BBS reports a non-statistically significant population trend for the Willamette 

Lowlands of -2.4 percent per year (95% CI -10.7 to 6.0) (Sauer et al. 2008). 

The objective for the area needed for a core habitat patch is based on a high density population at the 

State of Oregon’s EE Wilson Wildlife Area, near Corvallis. The area supports approximately 30 pairs 

in 300 acres of high quality shrubland habitat. Thus, after correcting for habitat quality outside of this 

high-quality reference habitat, we assumed 30 pairs could be supported on 450 acres of typical 

riparian shrubland habitat in the valley. 

Based on habitat characteristics and breeding requirements, a large subpopulation consisting of 25-35 

pairs or more, would require about a 450-acre habitat patch. A medium subpopulation of 15-25 pairs 

would require about a 300-acre patch, and a small population of 5-15 pairs would require about 150 

acres. 
Willamette Valley Conservation Study 

Appendix E. Population and Habitat Objectives E-11 

Listed Prairie Species Habitat Objectives 

The Recovery Plan for the Prairie Species of Western Oregon and Southwestern Washington 

(USFWS 2010a) does not include habitat objectives per se. For the listed plant species we met with 

the authors of the Recovery Plan, and others actively engaged in restoration of these imperiled 

species, to explore how much habitat would be necessary to meet the population objectives. With 

specific populations already targeted, the panel agreed that sufficient prairie habitat would be 

identified for the targeted grassland species (western meadowlark and Oregon vesper sparrow) and 

additional habitat objectives for the plant species was not warranted. 

For Fender’s blue butterfly (FBB) we examined the linear relationship between prairie patch size and 

minimum FBB population size, from the past five years (2009-2013) of 17 occupied FBB sites across 

the Willamette Valley. Most functioning networks consist of three subpopulations. To meet delisting 

criteria most recovery zones would need to support three or four functioning networks with each 

network needing to support a minimum of 400-1,000 butterflies, or approximately 130-330 

butterflies per subpopulation (if each subpopulation is expected to support 1/3 of the population). 

Using linear regression, we investigated the significance of the relationship between prairie patch 

size and minimum Fender’s blue butterfly population size. Using this relationship we calculated the 

minimum patch size range needed by dividing the area required to support a minimum of 130-330 

butterflies per subpopulation and a minimum of 400-1,000 butterflies per network. 

We found a significant relationship between prairie patch size and minimum Fender’s blue butterfly 

population size over the past five years (F = 

10.35, p = 0.006, R2

 = 0.33). Each hectare (ha) 

of prairie habitat translates to approximately a 

minimum FBB population of about 23 adults (10 

per acre). A Fender’s blue butterfly population 

that would likely contribute to delisting would 

require between 14.1 and 35.3 acres (5.7 and 

14.3 ha) of prairie habitat per subpopulation or a 

total between 42.3 and 105.3 acres (17.1 and 

42.6 ha) of prairie habitat per functioning 

network. 

Due to the lack of any similar information for Taylor’s checkerspot butterfly, we adopted the 

Fender’s blue butterfly standard for Taylor’s checkerspot. 

Wetlands 

Oregon’s Wetland Conservation Strategy (ODSL 1995) recommended that planning efforts should be 

made to identify priority wetlands, based on functional value and regionally representative wetland 

types for restoration and protection. The Willamette Valley and the Willamette Greenway were 

identified by the Oregon Department of State Lands (ODSL) as priority regions for wetland 

restoration and acquisition due the significant historical loss of wetlands, water quality issues, 

presence of rare wetland plant communities and species, threats due to urbanization, and landowner 

interest (ODSL 1995). This same approach, protecting priority wetlands, was recommended in the 

Strategic Conservation Management in Oregon’s Willamette Valley (USFWS 2014). 
Willamette Valley Conservation Study 

E-12 Appendix E. Population and Habitat Objectives 

To identify priority wetlands, we used spatial data provided by The Wetlands Conservancy which 

was the same data set that was used to identify wetlands of conservation concern for the Oregon 

portion of the Western Governors Association’s Crucial Habitat Assessment Tool or CHAT (WGWC 

2013). The CHAT scored and prioritized the conservation value of wetlands of conservation value by 

sub-watershed (Hydrologic Unit Code 8 [HUC-8]). By design this approach resulted in wetlands 

scoring high for conservation value in each subwatershed, and did not consider how they would score 

compared to wetlands across the entire Willamette Valley ecoregion. Using the same ecological 

attributes and weighting scheme as was used to identify wetlands of conservation value for the 

CHAT, the Wetlands Conservancy also mapped the conservation value of wetlands across the entire 

ecoregion resulting in a map that identified the wetlands of greatest conservation value across the 

entire ecoregion, rather than individual subwatersheds. We intersected the wetlands map with our 

vegetation map and targeted those wetlands that intersected our priority habitats for conservation 

(e.g., riparian forests and shrublands, wet prairies). 

Rivers and Streams 

There have been many recent studies and modeling efforts of the Willamette River and its major 

tributaries that identify areas of conservation significance. The studies and areas include the 

following: The Willamette River Planning Atlas (Hulse et al. 2002) which projected and analyzed 

alternative futures in the basin and identified areas of high restoration potential; mapping of the 2-

year floodplain along the mainstem Willamette River (River Design Group 2012a); the Middle Fork 

and Coast Fork (River Design Group 2012b) and lower McKenzie River (River Design Group 2013); 

the U.S. Army Corps of Engineers’ study that identified priority revetments for removal (Hulse et al. 

2013); mapping of cold water refugia along the mainstem (Hulse et al. 2007); mapping of “anchor 

habitats” by the Oregon Watershed Enhancement Board (OWEB 2014); and mapping of 

Conservation Opportunity Areas by ODFW (2006) and TNC (2012). 

The studies and conservation plans—summarized in Appendix A, all link the simplification of 

channel complexity and armoring along the Willamette River mainstem with the resultant loss of side 

channels, alcoves, and off-channel refugia as major contributors to the decline of aquatic organisms 

in the Willamette Valley (ODFW 2006, Hulse et al. 2002, NPCC 2004, WRI 2001, OPB 2000). The 

Pacific Lamprey Assessment and Template for Conservation Measures (Luzier et al. 2011) identified 

stream and floodplain degradation, primarily the extensive channelization and loss of side channels 

as a threat that ranked high for both scope and severity for Pacific lamprey in the Willamette basin. 

To address these issues, The Upper Willamette River Conservation and Recovery Plan for Chinook 

salmon and steelhead (ODFW and NMFS 2011), consistently recommends both the protection of 

intact riparian areas, floodplains, and high-quality off-channel habitats; and the restoration of areas to 

improve the amount, complexity, diversity, and connectivity of riparian, confluence, and off-channel 

habitats, as important actions to assist in the recovery of listed salmonids. Of course, these habitats 

are also important for terrestrial species as well, providing critical life history elements. 

The mainstem Willamette River and its major tributaries primarily serve as migration corridors and 

larval and juvenile rearing habitat. Therefore, the project team decided to focus conservation efforts 

on habitat features important to these life-cycle phases. We used a number of different data sources 

to assist in identifying priority areas for riverine conservation. The Willamette River Basin Planning 

Atlas (Hulse et al. 2002) prioritized areas for restoration, based on an analysis of the potential to 

restore channel complexity and floodplain forests, and the presence of sociocultural constraints, such 

as human population density, property value, transportation infrastructure, and the presence of prime 
Willamette Valley Conservation Study 

Appendix E. Population and Habitat Objectives E-13 

agricultural soils. Areas of high restoration potential with low sociocultural constraints were 

prioritized and mapped. We included these areas as conservation targets in the Marxan model. 

The U.S. Army Corps of Engineers completed a study that prioritized revetments for removal or 

modification to restore natural river function (Hulse et al. 2013). That study mapped the area along 

72 revetments whose hydrology during a 2-year recurrence interval flood would likely be influenced 

as a consequence of revetment removal or modification. These areas were termed zones of influence. 

Of the 72 zones of influence studied, 15 were identified as priority areas because they occur in areas 

previously prioritized for restoration by the Willamette River Basin Planning Atlas. We included 

those 15 priority zones of influence where they intersected with priority habitat types as conservation 

targets in the Marxan model. 

The Oregon Watershed Enhancement Board (OWEB) and the Willamette Special Investment 

Partnership (Willamette SIP) focus on two core geographic regions for investments in protecting and 

restoring the Willamette River—the historic meander corridor of the Willamette mainstem (including 

the first few river miles of the Coast and Middle Fork Willamette rivers); and seven selected tributary 

subwatersheds (OWEB 2014). Along the mainstem, the Willamette SIP targets major tributary 

confluences and river sections where there are opportunities to reconnect the river to its historic 

floodplain. These areas are called Anchor Habitats. Anchor Habitats were one of the data layers used 

in developing the Synthesis Map of Conservation Opportunity Areas (TNC 2012), and where they 

intersected priority habitat types, the Anchor Habitats were included as targets in the Marxan model. 

Floodplains inundated by a 2-year storm event have been mapped along the Willamette River from 

Eugene to Oregon City (River Design Group 2012a); the Middle Fork and Coast Fork of the 

Willamette River (River Design Group 2012b); and the McKenzie River below Leaburg Dam (River 

Design Group 2013). The Middle Fork analysis area extends 17 miles from Dexter Dam downstream 

to the confluence with the Coast Fork. The Coast Fork analysis area extends from two miles 

downstream of the Highway 58 Bridge to the confluence with the Middle Fork. Floodplain 

inundation mapping was completed to gain a better understanding of river corridor connectivity and 

to identify potential opportunities for protecting floodplain resources and restoring impaired habitats. 

We used the intersection of floodplain inundation maps with priority habitat types as targets in the 

Marxan model. 

 
Willamette Valley Conservation Study 

E-14 Appendix E. Population and Habitat Objectives 

This document continues on the next page. 
Willamette Valley Conservation Study 

Appendix F. Marxan F-1 

Appendix F. Marxan 

Introduction 

The Willamette Valley Marxan analysis was designed to identify in an integrated and efficient 

manner and building upon lands already conserved, key areas of the valley within which a network 

of core habitat patches could be established and threatened and endangered populations conserved. 

This process entailed evaluating thousands of areas throughout the entire Willamette Valley, to 

identify areas that could meet multiple conservation goals. This complexity makes it nearly 

impossible to select a highly efficient conservation network design, relying solely on expert 

knowledge. To deal with this challenge, we identified Priority Conservation Areas (PCAs) using the 

conservation network design optimization algorithm Marxan (Ball and Possingham 2000). Marxan 

(and its predecessors SPEXAN and SITES) has been used for many terrestrial and marine 

conservation assessments around the world (e.g., Beck and Odaya 2001, Andelman and Willig 2002, 

Noss et al. 2002, Leslie et al. 2003, Carroll et al. 2003, Floberg et al. 2004, USFWS 2013, Arid 

Lands Initiative 2014). 

Based on user-specified inputs, Marxan creates conservation designs that satisfy key principles of 

systematic conservation planning, including efficiency, complementarity, representativeness, and 

adequacy (Ardron et al. 2010). The Marxan algorithm quickly arrives at near-optimal conservation 

designs that meet user goals (e.g., 5,438 acres of western meadowlark habitat in the central valley) 

while minimizing user-specified constraints (e.g. estimated cost in dollars, total acreage, or more 

abstract constraints such as the level of human impact). Marxan also seeks to minimize the total outer 

perimeter of the conservation network in order to create a less fragmented solution. All of these 

factors (goals, constraints, and fragmentation) are considered by Marxan’s objective function. 

Marxan works by first generating a random initial conservation network design, then altering it 

slightly and testing the new version against its objective function. It iterates through this process 

millions of times to allow Marxan to thoroughly explore the enormous problem space. Early in the 

process, Marxan will sometimes move toward a design with a poorer objective function score. This 

approach, known as simulated annealing, is critical in helping the algorithm avoid this from 

happening (Game and Grantham 2008) so that more efficient solutions can eventually be achieved. 

There are a few key limitations to Marxan. The quality of its network design is dependent on the 

quality of the data used (e.g., landcover types, threatened and endangered species locations). For 

instance, there may be unmapped populations of listed species that could contribute to recovery that 

Marxan cannot factor into its network design. Marxan cannot factor in landowner interest, or pre‐

existing stakeholder and political conflicts (Ardon et al. 2010). As land-based conservation actions 

are dependent on landowner interest, significant opportunities may fall outside of the final network 

design. 

Before running Marxan, several methodological and conservation decisions had to be made. We 

needed to define the size and shape of Marxan planning units, select conservation features, choose 

data layers to represent the selected conservation targets, define which constraints or costs should be 

minimized, and calibrate Marxan parameters. After running the model, we also had to refine the 

boundary of the Marxan solution based on expert knowledge, as is recommended by Game and 

Grantham (2008). The remainder of this appendix describes how these decisions were made. 
Willamette Valley Conservation Study 

F-2 Appendix F. Marxan 

Planning Units 

Marxan requires that all input data layers be aggregated to polygon planning units (PUs) that 

seamlessly cover the analysis area. In other words, a spatial database is developed that includes, for 

each PU, the total acreage of each Marxan target as well as a “constraint” score. These PUs are the 

building blocks of the conservation network, and their geometry can greatly influence Marxan 

outputs. It is possible to use PUs that are based on natural ecological divisions like watersheds, or 

political divisions like land ownership parcels, but their irregular sizes and edge lengths can lead to 

selection biases and so regular grids are preferred. In this case, we chose a grid, and selected 

hexagons instead of squares because squares often result in overly rectilinear conservation designs. 

Marxan PU resolution should generally be no finer than the conservation target data can support and 

no coarser than is useful for management decisions (Ardon et al. 2010). We identified 250 acres as an 

appropriate PU size given uncertainty in the input data, and subdivided the 3,200,000-acre study area 

into a grid of 13,388 hexagons comprised of 250 acres each. 

Locking In Special Areas 

Marxan allows for some PUs to be “locked in” so that they are always included in the final 

conservation network design. This is useful for areas that are of key importance to a particular fine 

filter target, which may not have enough overlap with other targets to be picked up by the Marxan 

algorithm. It can also be appropriate to lock in areas that are already part of the conservation 

network, so that the solution builds off existing protected areas. For the Willamette Valley analysis, 

we locked in PUs representing both coarse and fine filter targets and portions of the existing 

conservation estate. 

We locked in 31 PUs (4,750 acres) for key populations of endangered plants (Bradshaw’s lomatium, 

Kinkaid’s lupine, and the Willamette daisy), using shapefiles provided by Rebecca Currin (USFWS) 

in 2014. We locked in 103 PUs (25,750 acres) for the Taylor’s checkerspot and Fender’s blue 

butterflies. The Taylor’s checkerspot population location data were provided by Richard Szlemp 

(USFWS) in 2013, and Fender’s blue locations data were provided by Tyler Hicks (Washington State 

University) in 2013. Experts on the endangered plants and butterflies in the valley agreed that 

locking in these fine filter targets was appropriate and sufficient. 

We also locked in two key bird areas delineated by Bob Altman of the American Bird Conservancy. 

One is the Indian Head Hills area near Coburg in the South Willamette Valley, which has a high 

density of declining grassland birds. The other is an area of pastures near Molalla where vesper 

sparrow and western meadowlark observations have occurred nearby. Including the bird areas added 

31 PUs, or 4,750 acres. Finally, we locked in 159 PUs (39,750 acres) that intersected the approved 

boundaries for the National Wildlife Refuges in the valley. 

Locking Out Areas Outside Oregon Department of Fish and 

Wildlife Conservation Opportunity Areas 

In the fall of 2015, the Oregon Department of Fish and Wildlife (ODFW) finalized an update to their 

Conservation Opportunity Areas (COAs). ODFW also used Marxan to identify priority areas. They 

had a different suite of target species and habitats than the WVCS, but to the degree possible, we 

wanted the WVCS PCAs to be a subset of the ODFW COAs while still meeting WVCS conservation 
Willamette Valley Conservation Study 

Appendix F. Marxan F-3 

objectives. In order to accomplish this, we “locked out” all PUs that did not have any intersection 

with the ODFW COAs, unless they were already locked in as previously described. Marxan never 

includes locked out PUs in its solutions regardless of how much target habitat they contain. 

Marxan was able to identify an efficient design almost entirely within the ODFW COAs with the 

notable exception of particular subpopulations of threatened and endangered species the recovery 

team locked-in to the final design. Because the ODFW COAs and the WVCS PCAs were created 

using different PUs, there is some mismatch in their edges. Overall, 91.0 percent of the area of the 

final PCAs falls within the area of ODFW COAs, providing a highly consistent map of important 

areas for conservation actions in the valley. 

Data Layers Representing Conservation Targets 

The priority habitats for the WVCS are prairie (wetland and upland), oak savanna, oak woodland, 

riparian forest, and riparian shrublands. The Oregon Conservation Strategy (ODFW 2006) was the 

basis for selecting these habitats, which are described in Appendix C. 

After deciding on target habitats, we had to identify the best available spatial data representing the 

location of these habitats in the Willamette Valley. Numerous Land Use/Land Cover (LULC) layers 

are available in the valley, including the National Land Cover Dataset (NLCD), The Coastal Change 

Analysis Program (C-CAP) Land Cover layer, LANDFIRE Current Vegetation Class, the Northwest 

Habitat Institute (NWHI) vegetation layer, and others. Each dataset has its strengths and weaknesses, 

and so we decided to combine all relevant layers into a single spatial database. To do this, a Landsat 

image from 2010 was broken up into polygons with distinct spectral signatures using eCognition, 

producing about 250,000 polygons. Because these polygons were often too large to capture wetlands, 

which were important to this study, we also incorporated a modified version of the National 

Wetlands Inventory (NWI). This data layer, which was developed by the Institute for Natural 

Resources in Portland, Oregon, was essentially “burnt in” to the eCognition polygon layer, and the 

NWI attributes of these wetland polygons were used to assign their vegetation class. 

The other polygons were assigned vegetation classes based on agreement among existing LULC 

maps and other ancillary information such as LiDAR-derived vegetation height. The final product 

was a set of polygons that covered the entire study are, each with a vegetation type assignment based 

on multiple datasets. The dataset was also hand edited in 2014 after field visits revealed that some 

areas that were mapped as pasture had been converted to vineyards or Christmas tree farms. Because 

these high structure agriculture types are easy to detect with high resolution imagery, many of these 

errors could be caught and corrected in the office. 

The composite vegetation layer had 20 different vegetation classes (Table F1). Some of these classes 

directly corresponded to our priority habitats, and were used as Marxan Targets. However, because 

true prairie habitat is now very rare in the valley, we chose to represent prairie with landcover types 

that are fairly compatible with grassland-dependent species, and can support our target species well, 

with minor changes in management (e.g., delaying haying of pasture until after chicks have fledged). 

These vegetation classes include unmanaged pasture, grasslands within protected areas, and 

pasture/hay. Together, these classes comprised the prairie target habitat in the Marxan model. To 

avoid prioritizing prairie habitat that was never historically open, we only targeted these areas when 

they overlapped with historical prairie or savanna as defined by the 1951 historical vegetation map of 

the Willamette Valley (Christy and Alverson 2011). We also did not target oak savanna areas that 

were not historically open. 
Willamette Valley Conservation Study 

F-4 Appendix F. Marxan 

Table F1. Classes in the composite vegetation layer prepared for this study, with their 

correspondence to Marxan target habitats 

Vegetation Class Corresponding Marxan Target Habitat 

Cultivated Agriculture Not a target 

Deciduous Forest Not a target 

Developed/High Intensity Not a target 

Developed/Low Intensity Not a target 

Developed/Medium Intensity Not a target 

Developed/Open Space Not a target 

Grassland/Herbaceous in Protected Areas Grassland 

Harvested Forest - Regeneration Not a target 

High Structure Agriculture Not a target 

North Pacific Maritime Dry-Mesic Douglas-firWestern Hemlock Forest Not a target 

North Pacific Oak Woodland Oak Woodland 

Oak Savanna Oak Savanna 

Pasture/Hay Prairie 

Riparian Forest Riparian Forest 

Riparian Shrubland Riparian Shrubland 

Scrub/Shrub Not a target 

Seed/Sod Grass Not a target 

Temperate Pacific Freshwater Emergent Marsh Not a target 

Unconsolidated Shore Not a target 

Unmanaged Pasture Grassland 

Water Not a target 

Although the oak woodland target habitat was directly represented in the composite vegetation layer, 

there are not enough acres of oak-dominant woodland in the valley to meet population objectives for 

the target species (slender-billed white-breasted nuthatch). There are, however, many acres of 

woodlands which are dominated by other types of trees but that also include a sizable minority of oak 

trees. Because these areas could be restored to oak woodland with active management (e.g., removal 

of conifers), we chose to include them in the oak woodlands Marxan target. This gave Marxan more 

flexibility when satisfying oak woodland goals, and thus allowed for a more efficient solution. 

Stacked Targets 

In many cases, not all parts of a habitat’s distribution area are equivalent in terms of conservation 

delivery. For example, planners might value all patches of a particular habitat type, but recognize that 

patches over a certain size are likely to be more functional than smaller patches. Thus, they might 

favor large patches of this habitat when creating a network design, while accepting smaller patches 

when they are needed to meet acreage goals or when they overlap with other important targets. In 

order to give Marxan a similar preference for certain subsets of a target (e.g., larger patches), 

“stacked targets” can be used. This essentially means that although all of a habitat distribution is 

targeted by Marxan, those areas with special attributes that make them more valuable are targeted 

twice and are more likely to be included in the final conservation network design. In a Marxan 

analysis in the Columbia Plateau (ALI 2014), for example, stacked targeting of shrub steppe patches 
Willamette Valley Conservation Study 

Appendix F. Marxan F-5 

over 500 acres in size allowed Marxan to favor these areas while still selecting smaller patches as 

needed. 

In the Willamette Valley, stacked targets were used for all habitat types (Table F2). For each priority 

habitat, in order to select areas where the targeted species are known to occur, we favored areas that 

were within 2 km of a recent observation (5 years or less) of the habitat’s target species. In the case 

of prairie habitat, because our broad definition included such a large acreage of agricultural lands that 

could potentially be managed to support grassland species as well, we only targeted those areas that 

were within 2 km of either a recent western meadowlark or vesper sparrow observation. 
Table F2. Marxan targets and their acreage goal levels. Goal levels were capped at 70% of available acreage. The “base” habitats are 

shown in bold, and their “stacked targets” are nested beneath them in italics. Each subsection of the valley (North, South, and Central) had 

unique targets (see Executive Summary and Appendix E for more information). 

Target 

Habitat acreage goals 

based on population 

targets 

Available habitat 

(acres) 

Marxan acreage goals 

(capped at 70% of 

available) 

North Valley 

Oak Savanna in historically open areas 1,500 3,371.8 1,500.0  within 2km of a recent western bluebird observation 1,500 235.2 164.6 Prairie* in historically open areas 2,813 79,820.0 **  within 2km of a recent vesper sparrow observation 750 8,984.6 750.0  within 2km of a recent western meadowlark observation 2,063 9,948.9 2,063.0 Oak Woodland 16,500 63,574.8 16,500.0  within 2km of a recent white-breasted nuthatch observation 16,500 13,513.6 9,459.5Riparian Forest 5,400 46,014.2 5,400.0  within 2km of a recent yellow warbler observation 5,400 10,497.6 5,400.0  that intersects anchor habitats with high restoration potential 5,400 1,756.9 1,229.9 that intersects Willamette floodplain segments with cold points 5,400 172.3 120.6 that intersects wetlands with high WGA CHAT scores 5,400 4,237.6 2,966.3  that intersects areas with high suitability for revetment removal 5,400 1,920.8 1,344.6Riparian Shrubland 1,650 11,460.0 1,650.0  within 2km of a recent yellow-breasted chat observation 1,650 758.3 530.8  that intersects anchor habitats with high restoration potential 1,650 495.6 346.9

F-6

______________________________________________________________________________________________

Appendix F. Marxan ______________________________________________________________________________________________ Willamette Valley Conservation Study
Target 

Habitat acreage goals 

based on population 

targets 

Available habitat 

(acres) 

Marxan acreage goals 

(capped at 70% of 

available) 

 that intersects Willamette floodplain segments with cold points 1,650 76.5 53.5  that intersects wetlands with high WGA CHAT scores 1,650 1,684.7 1,179.3  that intersects areas with high suitability for revetment removal 1,650 350.7 245.5 

Central Valley 

Oak Savanna in historically open areas 1,763 3,176.7 1,763.0  within 2km of a recent western bluebird observation 1,763 1,144.7 801.3 Prairie* in historically open areas 7,211 76,253.3 **  within 2km of a recent vesper sparrow observation 1,773 8,610.3 1,773.0  within 2km of a recent western meadowlark observation 5,438 15,060.2 5,438.0 Oak Woodland 16,500 41,655.5 16,500.0  within 2 km of a recent white-breasted nuthatch observation 16,500 15,016.7 10,511.7 Riparian Forest 4,860 24,319.0 4,860.0  within 2 km of a recent yellow warbler observation 4,860 9,751.7 4,860.0  that intersects anchor habitats with high restoration potential 4,860 2,070.8 1,449.5  that intersects Willamette floodplain segments with cold points 4,860 266.5 186.5  that intersects wetlands with high WGA CHAT scores 4,860 3,712.1 2,598.5  that intersects areas with high suitability for revetment removal 4,860 2,464.2 1,724.9 Riparian Shrubland 1,950 5,187.4 1,950.0 

______________________________________________________________________________________________ Willamette Valley Conservation Study

Appendix F. Marxan

______________________________________________________________________________________________

F-7
Target 

Habitat acreage goals 

based on population 

targets 

Available habitat 

(acres) 

Marxan acreage goals 

(capped at 70% of 

available) 

 within 2 km of a recent yellow-breasted chat observation 1,950 936.3 655.4  that intersects anchor habitats with high restoration potential 1,950 430.3 301.2 that intersects Willamette floodplain segments with cold points 1,950 80.4 56.3 that intersects wetlands with high WGA CHAT scores 1,950 829.2 580.4  that intersects areas with high suitability for revetment removal 1,950 536.2 375.3

South Valley 

Oak Savanna in historically open areas 1,388 5,965.1 1,388.0  within 2 km of a recent western bluebird observation 1,388 757.8 530.4 Prairie* in historically open areas 8,748 113,398.8 **  within 2 km of a recent vesper sparrow observation 2,185 23,411.6 2,185.0  within 2 km of a recent western meadowlark observation 6,563 32,772.5 6,563.0 Oak Woodland 16,200 54,061.7 16,200.0  within 2 km of a recent white-breasted nuthatch observation 16,200 15,981.1 11,186.8Riparian Forest 4,860 32,417.1 4,860.0  within 2 km of a recent yellow warbler observation 4,860 11,200.5 4,860.0  that intersects anchor habitats with high restoration potential 4,860 3,370.6 2,359.4 that intersects Willamette floodplain segments with cold points 4,860 634.9 444.4 that intersects wetlands with high WGA CHAT scores 4,860 5,772.9 4,041.0 

F-8

______________________________________________________________________________________________

Appendix F. Marxan ______________________________________________________________________________________________ Willamette Valley Conservation Study
Target 

Habitat acreage goals 

based on population 

targets 

Available habitat 

(acres) 

Marxan acreage goals 

(capped at 70% of 

available) 

 that intersects areas with high suitability for revetment removal 4,860 1,701.0 1,190.7 

South Valley Riparian Shrubland 1,500 6,486.4 1,500.0 within 2 km of a recent yellow-breasted chat observation 1,500 1,411.3 987.9 that intersects anchor habitats with high restoration potential 1,500 1,156.7 809.7 

 that intersects Willamette floodplain segments with cold points 1,500 275.6 192.9  that intersects wetlands with high WGA CHAT scores 1,500 1,622.1 1,135.5  that intersects areas with high suitability for revetment removal 1,500 369.3 258.5 

* As was described above, the Prairie target includes Grassland/Herbaceous in protected areas, Pasture/Hay, and Unmanaged Pasture.

** Because the 10-year Prairie acreage goals can easily be met in areas near western meadowlark and vesper sparrow observations, we did not target prairie that

was further than 2 km from an observation. 

______________________________________________________________________________________________ Willamette Valley Conservation Study

Appendix F. Marxan

______________________________________________________________________________________________

F9
Willamette Valley Conservation Study 

F-10 Appendix F. Marxan 

To identify areas near existing breeding populations, we compiled recent bird observation data from 

numerous sources. These included survey data gathered by the American Bird Conservancy, The 

Portland Bureau of Environmental Services, the Portland Chapter of The Audubon Society, the 

Oregon Department of Fish and Wildlife, and The Oregon Chapter of The Nature Conservancy. We 

also used data from a vesper sparrow survey conducted by Bob Altman in 2013, some incidental 

vesper sparrow observation also provided by Bob Altman, Breeding Bird Survey data, and vetted 

eBird observations. 

Because we wanted to focus on areas that currently or very recently had breeding populations, we 

only used breeding season records from 2008 to 2013. Breeding season was defined as May-June, but 

for the resident species (western meadowlark and slender-billed white-breasted nuthatch) we also 

used the last half of April, and for the migrant species (yellow warbler, western bluebird, vesper 

sparrow, and yellow-breasted chat) we included the first half of July. 

In addition to favoring habitat near recent occurrences of the associated target species, we also used 

several other stacked targets for riparian forests and shrublands. Aquatic habitats were not directly 

targeted in this analysis, but we did favor riparian areas that could provide benefits to aquatic systems 

while still meeting terrestrial habitat goals. We did this by configuring Marxan so that it preferred to 

meet acreage goals for riparian targets in places where they overlapped with existing aquatic priority 

areas (Table F2). 

These existing aquatic priority areas included the following GIS layers: sections of the Willamette 

River floodplain with high restoration potential and low social impact from the Willamette River 

Planning Atlas (Hulse et al. 2002); the Willamette River’s 2-year floodplain (River Design Group 

2012a); layers from a US Army Corps of Engineers’ study that identified priority revetments for 

removal (Hulse et al. 2013); cold water refugia (Hulse et al. 2007); “anchor habitats” mapped by the 

Oregon Watershed Enhancement Board (OWEB 2014); and wetlands of conservation concern 

identified by The Wetlands Conservancy for the Western Governors Association’s Crucial Habitat 

Assessment Tool or CHAT (WGWC 2013). We overlaid these areas of conservation significance 

with the riparian forest and shrubland habitat layers, and the areas of intersection became targets for 

conservation. 

Setting Goal Levels 

Marxan requires specific goals levels for each target. They can either be a percent of the total 

distribution or specific acreage goals. For this analysis, acreage goals were identified for target 

habitats by estimating the amount of land required to support resilient populations of their particular 

target species. This process is described in Appendix E. 

For all targets, we capped the goals at 70 percent of the total available distribution. Targeting more 

than that can cause Marxan to include every PU that has even a very small portion of the target in the 

solution, which leads to inefficient designs. 

Constraint Layer 

Marxan uses a constraint layer in order to optimize the selection of spatial units (This is called the 

cost layer in the Marxan documentation, but the term constraint is preferred here because this 

analysis does not rely solely on an economic cost layer, and so referring to cost can be misleading). 

The constraint layer allows it to favor PUs that are less constrained in their ability to meet 
Willamette Valley Conservation Study 

Appendix F. Marxan F-11 

conservation goals (though Marxan may still select highly constrained PUs if they are essential to 

meet a goal). To prepare the constraint layer, we identified a set of variables that can limit the 

landscape’s ability to meet conservation goals, and then compiled the best available spatial data for 

each of these factors. We then used different combinations of the variables to develop three 

alternative constraint layers. One of the constraint layers represented environmental integrity, another 

represented socioeconomic constraints, and the third was designed to make Marxan favor areas 

inside the Synthesis Conservation Opportunity Area (COA) polygons developed by the Oregon 

Chapter of the Nature Conservancy (TNC 2012). 

The environmental integrity constraint layer is based on two variables: Land Use/Land Cover 

(LULC) types, and the number of highway miles in a PU. The social constraints layer combines three 

variables: land cost, actively farmed prime agricultural farmland, and tax lot size. The Synthesis 

COA layer considers the location of the PU relative to the location of COA. All constraint variables 

are described in detail below. 

Integrity Factors 

Land Use/Land Cover 

The LULC cover types were based on the same composite vegetation layer that we used for target 

habitats, described above. Each cover type was scored for its general wildlife value on a scale of 1 to 

10, with the best cover type(s) receiving a 1 and the worst cover type(s) receiving a 10 (Table F3). 

All of the target habitats (e.g., prairies, oak woodlands) received a score of 1. Developed areas, high 

intensity agriculture, and grass seed fields were scored high for their wildlife constraints, meaning 

that Marxan would attempt to avoid those areas. 

Table F3. LULC types in the Willamette Valley and their wildlife conservation value scores. 

Land Use/Land Cover Score 

Cultivated Ag 8 

Deciduous Forest 5 

Developed/High Intensity 10 

Developed/Low Intensity 8 

Developed/Medium Intensity 10 

Developed/Open Space 5 

Grassland/Herbaceous 1 

Harvested Forest – Regeneration 8 

High Structure Ag 10 

North Pacific Maritime Dry-Mesic Douglas-fir-Western Hemlock Forest 5 

North Pacific Oak Woodland 1 

Oak Savanna 1 

Pasture/Hay 5 

Riparian Forest 1 

Riparian Shrubland 1 

Scrub/Shrub 1 

Seed/Sod Grass 8 

Temperate Pacific Freshwater Emergent Marsh 1 

Unconsolidated Shore 1 

Unmanaged Pasture 3 

Water 5 
Willamette Valley Conservation Study 

F-12 Appendix F. Marxan 

Road Density 

Negative effects of roads on ecosystems and species have been well documented. These effects 

include, but are not limited to, “mortality..., modification of animal behavior, alteration of the 

physical environment, alteration of the chemical environment, spread of exotics, and increased use of 

areas by humans” (Trombulak and Frissell 2000). Based on expert opinion, however, small, 

secondary roads were not considered to be a constraint on our target avian species because they can 

easily and safely cross them. Further, the breeding territories of some of these species are known to 

include secondary roads, and their behavior does not appear to be affected by such roads. Only state 

highways were considered to be constraining in this analysis. 

We calculated the number of highway miles per PU, then linearly scaled this variable from 1 to 10 to 

create an index of highway density. We scaled all constraint variables from 1 to 10 so that variables 

with large ranges (e.g., tax lots) would not have excessive influence on the final index value and 

model results. All things being equal, Marxan will favor PUs with the lower highway density index 

over PUs with similar biological attributes but with a higher highway density index. 

Social Factors 

Prime Agricultural Farmland		

For reasons discussed above, we wanted Marxan to avoid prime farmland as much as possible. An 

area is designated as prime agricultural farmland based on its soil type. We mapped actively farmed 

areas with prime agricultural farmland soils, and then calculated the percent of this land use type in 

each PU. If a PU was 100 percent actively farmed prime agricultural farmland, then it was given a 

score of 10 (highly constrained; to be avoided). If it had none of these areas, it was assigned a value 

of 1 (not constrained, to be favored). 

Tax Lot Size

Favoring PUs with larger average lot sizes over PUs dominated by small lots makes it easier to 

achieve habitat objectives, because cobbling a large number of small parcels together is generally 

inefficient and logistically complex. Using county tax lot data for all areas in the Willamette Valley 

outside of Urban Growth Boundaries (UGBs), we calculated the average tax lot size within each PU. 

We then linearly scaled and inverted these values to generate a tax lot size index, where PUs with the 

smallest mean lot size had a score of 10, and those with the largest had a score of 1. PUs inside 

UGBs were assigned the maximum value of 10. 

Land Value

We also used appraised land values compiled from county tax lot data in our constraints layer. When 

land value is used as a constraint, Marxan will essentially attempt to minimize the purchase price of 

lands selected while still meeting the conservation goals. Mean land value was calculated for each 

250-acre PU in areas outside UGBs. The mean was about $25,000 per acre, with a range of less than 

$500 to well over $1 million per acre. Marxan will avoid higher land cost areas if it can achieve 

conservation goals on lower cost land. We assigned the PUs a cost score based on the average land 

value (Table F4). 

 
Willamette Valley Conservation Study 

Appendix F. Marxan F-13 

Table F4. Constraint scores derived from average cost per acre for each PU. The most 

expensive PUs are the most constrained (10), and the cheapest are the least constrained (1). 

Mean Price per Acre ($) Score Mean Price per Acre ($) Score 

0-10,000 1 >50,000-60,000 6 

>10,000-20,000 2 >60,000-70,000 7 

>20,000-30,000 3 >70,000-80,000 8 

>30,000-40,000 4 >80,000-90,000 9 

>40,000-50,000 5 >90,000 or in UGB 10 

Synthesis Conservation Opportunity Areas 

We used conservation priority areas identified in a previous multi-partner analysis as a third 

constraint layer. These areas were mapped by the Oregon Chapter of The Nature Conservancy 

(TNC), which worked with conservation partners to produce a synthesis of the major Willamette 

Basin planning efforts. These prior planning efforts included: TNC’s Willamette Valley–Puget 

Trough–Georgia Basin Ecoregional Assessment (Floberg et al. 2004); the Pacific Northwest 

Ecosystem Research Consortium’s Willamette River Basin Alternative Futures Analysis (Hulse et al. 

2002); the ODFW’s Oregon Conservation Strategy (ODFW 2006); critical habitat designations and 

recovery plans for listed species; and Oregon’s Greatest Wetlands as delineated by The Wetlands 

Conservancy (2005). 

The TNC analysis found a large degree of overlap between the plans, but significant differences as 

well. The effort resulted in the development of a Willamette Basin Synthesis Map of Conservation 

Opportunity Areas (COAs). 

These COAs represent the shared priorities of many key partners in the Valley, and we wanted to 

take advantage of this valuable product while allowing Marxan to select areas outside the Synthesis 

COAs if they had especially high conservation value. We chose not to constrain the solution to only 

those PUs that intersected the Synthesis COAs, as we did with the updated ODFW COAs, because 

the Synthesis COAs have a smaller footprint in the WVCS analysis area (972,916 acres vs. 1,168,872 

in the ODFW COAs) which would make it harder for Marxan to efficiently satisfy WVCS objectives 

in these areas. 

In order to keep the new design mostly within the Synthesis COAs while giving Marxan some 

flexibility, we made areas outside of COAs more constrained than areas within Synthesis COAs. 

Each PU outside of a Synthesis COA was scored with a 10 (constrained by the absence of a COA), 

and a PU wholly within a Synthesis COA received a score of 1 (not constrained). PUs that span a 

Synthesis COA boundary were scored by the percent of the PU outside the Synthesis COA. For 

example, if 80 percent of the PU was outside the COA, it received a score of 8. 

Factor Weights 

For constraint layers made of combinations of variables, relative weights were assigned to the 

individual factors. Larger weights (coefficients) were assigned to those factors believed to be more 

important in constraining an area’s ability to meet conservation goals than other factors. Weights 

used in the Marxan analysis are shown in Table F5. 
Willamette Valley Conservation Study 

F-14 Appendix F. Marxan 

Table F5. Weights for the variables rolled up into the landscape integrity and socioeconomic 

constraint indices 

Landscape Integrity Variables Weight (0-1) Socioeconomic Variables Weight (0-1) 

LULC 0.7 Land Cost 0.4 

Highway Miles 0.3 Lot Size 0.3 

Landscape Integrity Total 1 Prime Farmland 0.3 

Socioeconomic Total 1 

Combining All Constraints 

Because Marxan works with only one constraint layer, the three constraint layers (Integrity, Social, 

Synthesis COAs) were rolled up into a single index of combined constraints. Landscape Integrity and 

Socioeconomic constraints were each given a weight of 0.3 and the COAs constraint layer was given 

a weight of 0.4, for a total of 1. The combined constraints index is a linear combination of all the 

constraint factors (Table F6). These were calculated for each PU and scaled from 1 to 10, multiplied 

by the coefficients in the table below, then added together. The coefficients are the individual factor 

weights multiplied by the weight given to the category of constraint. For example, the coefficient for 

land use/land cover cost is 0.21 [0.7 (individual factor weight) * 0.3 (landscape integrity weight)]. 

Table F6. Factor weights used in combined constraint index 

Constraint Weight 

Landscape Integrity 

 Land use/land cover 0.21 

 Length of highway in PU 0.09 

Social Factors 

 Land Cost 0.12 

 Lot Size 0.09 

 Prime agricultural soils 0.09 

Synthesis COAs 0.4 

Total 1 

Calibrating Marxan 

After selecting the targets, constraint layer, and goal levels, the Willamette Valley Marxan model 

was calibrated to ensure that it was consistently finding very good solutions. For Marxan, a lower 

objective function score is better than a higher score as it indicates that a particular conservation 

design is obtaining the required goals efficiently. Parameters that require calibration are: the number 

of iterations, the boundary length modifier, the range of the constraint layer, and the species penalty 

factor. The effect of these parameters on Marxan solutions and the calibration procedures are 

described below. 
Willamette Valley Conservation Study 

Appendix F. Marxan F-15 

Calibrating the Number of Iterations 

During a single run, Marxan iterates through millions of different conservation network designs, 

evaluating each one. By adjusting the number of iterations per run, users can give Marxan more or 

less time for the runs to converge on spatially similar, near-optimal solutions. The design problem 

that Marxan solves can vary greatly in complexity, depending on the number of PUs and the number 

of targets. The more complex the problem is, the more time is required to attain very low-scoring 

solutions in most runs. To be sure that the number of iterations was high enough for Marxan to 

achieve converging and low-scoring solutions, eight versions of the model, differing only in this 

parameter, were run 100 times each(Table F7). 

As the number of iterations was increased, the score went down; this indicates that the model was 

finding better solutions when given more time. The range in scores also decreased, meaning that the 

100 runs became more consistent with each other. Range over mean is a useful metric—when it 

levels off (Figure F1), it indicates that further increases to the number of iterations will not improve 

consistency and scores, and would thus add processing time with little benefit. Based on this 

analysis, we used 20 million iterations per run in the Willamette Valley Marxan analysis. 

Table F7. Marxan number of iterations calibration results. Each row summarizes 100 runs. 

No. of 

Iterations 

Min Score Max Score Mean Score Range Range/ 

Mean 

Processing Time 

2.5 million 8,994,336.3 8,994,964.9 8,994,602.0 628.6 0.0070% 4 mins and 16 secs 

5 million 8,994,068.5 8,994,402.7 8,994,221.2 334.2 0.0037% 6 mins and 49 secs 

7.5 million 8,993,945.8 8,994,272.5 8,994,077.4 326.7 0.0036% 8 mins and 52 secs 

10 million 8,993,904.6 8,994,158.3 8,994,021.0 253.7 0.0028% 11 mins and 5 secs 

15 million 8,993,842.1 8,994,045.3 8,993,938.7 203.1 0.0023% 

14 mins and 43 

secs 

20 million 8,993,784.5 8,993,990.1 8,993,890.9 205.6 0.0023% 

19 mins and 51 

secs 

25 million 8,993,764.6 8,993,948.8 8,993,855.5 184.2 0.0020% 

23 mins and 45 

secs 

30 million 8,993,765.9 8,993,922.7 8,993,829.9 156.8 0.0017% 29 mins and 9 secs 
Willamette Valley Conservation Study 

F-16 Appendix F. Marxan 

Figure F1. Change in range/mean of scores with number of iterations. The black 

line is a power equation fitted to the blue points with an R2

 value of 0.954.

Calibrating the Boundary Length Modifier 

Another important Marxan parameter is the Boundary Length Modifier (BLM). It controls the level 

of spatial clumping in the solution. If the BLM is set to 0, then solutions will be formed with no 

regard to their overall pattern, and are typically very dispersed. As the BLM is increased, Marxan’s 

solutions become more clumped and connected, because the algorithm favors PUs adjacent to those 

already selected over equally valuable PUs that are isolated from previously selected ones. This is a 

key parameter because, as was previously discussed, fragmented systems can create undesirable 

conditions for wildlife and can make management more difficult and costly. 

To calibrate this parameter, we ran multiple versions of the model that differed only in their BLM 

values (Figure 2). As the BLM values (point labels) decrease, the total boundary length (y-axis) 

increases and the total constraint (x-axis) of the solutions increases. Based on this chart as well as 

maps of the solutions at each BLM setting, we decided on a BLM value of 0.3, which produced a 

solution with a moderate overall constraint score that also appeared reasonably unfragmented on the 

map. 

Calibrating the Species Penalty Factor 

The Species Penalty Factor (SPF) is a multiplier for each Marxan target that determines a scoring 

penalty if Marxan fails to meet user goals for that target (Game and Granthem 2008). Although it is 

called the Species penalty factor, this parameter also applies to habitat types and other targets. 

According to Ardron et al. (2010), Marxan is considered to be performing best when all target goals 

0.00000

0.00001

0.00002

0.00003

0.00004

0.00005

0.00006

0.00007

0.00008

0 5 10 15 20 25 30 35

Range of Score/ mean score

Number of Iterations (Millions)
Willamette Valley Conservation Study 

Appendix F. Marxan F-17 

Figure 2. Changes in total boundary length and total cost of the solution as the boundary 

length modifier value changes. BLM values are shown beside each data point. 

are met in 70-90 percent of runs. Using an SPF of 100 for all targets as a somewhat arbitrary starting 

value, we found that all goals were met in about 89 percent of Marxan runs, which falls in the desired 

range. Thus, an SPF of 100 for all Marxan targets seemed appropriate and further calibration was not 

required. 

Refinement of Marxan Outputs 

We ran Marxan with the acreage goals from Table F2 and all parameters specified above. Due to the 

complexity of the problem (there are 213,388 possible network designs), Marxan is unable to guarantee 

finding the single design that minimizes the objective function to the maximum extent possible 

(Ardon et al. 2010). To increase our confidence that the final design was a very good solution, we 

completed 100 runs, each with 20,000,000 iterations. Marxan then selected as the “best solution” the 

single most efficient network design (i.e., the design with the best objective function score) out of the 

100 runs tested. During these 100 runs of 20 million iterations each, 2 billion alternative conservation 

network designs were evaluated. We used the best solution from these runs as the basis for our PCAs. 

To create draft PCAs, we merged contiguous PUs into single PCAs. The result was a set of 136 

PCAs ranging in size from single, isolated PUs (250 acres each), to 137 merged, contiguous PUs 

(34,250 acres). 

0

0.01

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

0.18 0.2

0.22 0.25

0.3

0.35

0.4 0.45

0.5

14,000

16,000

18,000

20,000

22,000

24,000

26,000

28,000

30,000

32,000

2,000 2,500 3,000 3,500 4,000

Boundary Length (meters)

Sum of constraint index for selected PUs

Boundary Length

Modifier Value
Willamette Valley Conservation Study 

F-18 Appendix F. Marxan 

Because Marxan is a decision support tool, designed to guide the selection of an efficient 

conservation reserve, its output should never be interpreted as “The Answer” (Ardon et al., 2010) An 

external review is recommend as a “reality check” of the results. We conducted that check and based 

on expert knowledge of the valley, we made some minor refinements to this Marxan solution. We 

reduced fragmentation by deleting isolated PCAs that were made up of only 1 or 2 PUs, unless they 

had been locked in for rare plants or butterflies. This removed 50 PUs (12,500 acres). We also 

removed two PUs (500 acres) that had almost no intersection with either the TNC Synthesis or the 

revised ODFW COAs and included only riparian habitat. 

To ensure we came very close to meeting our goals, we then replaced much of the habitat from the 

deleted PCAs by adding PUs to the design. We selected several PUs, at the edges of existing PCAs, 

that had a high habitat density. We also enhanced connectivity in the design by adding PUs between 

PCAs that were separated by only one or two PUs, as long as there was some habitat in the 

intervening PUs. Finally, we added in PUs containing several key places in the existing conservation 

estate that were not included in the solution. These included the Chahalpam Wildlife Area, near 

Stayton, OR, as well as the Trappist Abbey near Lafayette, Oregon. In total, we added 43 PUs back 

in (10,750 acres) to the Marxan solution. The final conservation design includes 76 PCAs made up of 

1,273 PUs (318,250 acres). 
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-1 

Appendix G. Priority Conservation Areas 

Introduction 

Conservation partners working in the Willamette Valley have completed several major planning 

efforts that identified areas within the valley that provide, or could provide with restoration, 

significant benefits for water quality, watershed health, wildlife habitat, species conservation, and 

other environmental values (Appendix A). These planning efforts differed in goals, methodologies, 

and scope, but many produced spatially explicit recommendations for where conservation work 

should be focused. In total, these assessments identified almost half of the Willamette Valley 

Ecoregion as a priority for conservation. 

The Nature Conservancy (TNC) worked with conservation partners to synthesize the findings of the 

major Willamette Basin planning efforts to produce the Willamette Basin Synthesis Map of 

Conservation Opportunity Areas (COAs). In developing the Oregon Conservation Strategy, the 

Oregon Department of Fish and Wildlife also mapped COAs. COAs are defined by ODFW as 

“landscapes where broad fish and wildlife conservation goals could best be met” (ODFW 2006). 

They were established because “focusing investments on priority landscapes can increase likelihood 

of long-term success over larger areas, improve funding efficiency, and promoting cooperative 

efforts across ownership boundaries” (ODFW 2006). There is a high degree of overlap between the 

two mapping efforts. These COAs are recognized by conservation partners in the valley as providing 

a spatially-explicit strategic framework within which to focus conservation actions. The Service 

supports and is committed to working within this strategic framework. 

Priority Conservation Areas 

Because the Service’s goals are a subset of the goals of the various planning efforts, the Service 

identified a subset of COAs to focus actions that could best meet the goals of the WVCS. The Maxan 

analysis identified 76 areas, within which, our habitat objectives could be met (see Figures 1, 2, and 

3). We are calling these areas Priority Conservation Areas (PCAs).The PCAs lay almost entirely 

within the boundaries of the previously identified COAs. Only when we identified an important 

population of a threatened or endangered species (a fine-filter target) beyond an existing COA does a 

PCA occur outside of a previously mapped COA. 

PCAs were typically named after the name of the Willamette Valley Synthesis COA (TNC 2012) in 

which the PCA is located. In some instances, multiple PCAs are within a single large COA. When 

this happened, we added a location modifier such as “north” or “south”. In some instances, a PCA 

spans more than one COA. When that happened, we included both COA names, such as Finley 

NWR/Muddy Creek, separating the 2 COA names with a slash (/). In a few instances new names 

were developed to clarify the location of the PCA. 

Table G1 provides the name for each PCA, its size (acreage), the County within which it is located, 

and a brief description of the conservation targets present. Federally listed species are followed by 

their listing status (LE = Listed Endangered, LT = Listed Threatened). If the PCA includes 

designated Critical Habitat (CH) for the species, the acronym ‘CH’ follows the listing status. As 

objectives were developed for the southern, central, and northern sections of the valley, the PCAs are 

identified by color which section they occur (South PCAs 1-17, Central 18-45, North 46-72). 
Willamette Valley Conservation Study 

G-2 Appendix G. Priority Conservation Areas 

This document continues on the next page. 
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-3 

 

Figure 1. Priority Conservation Area Map South Zone 
Willamette Valley Conservation Study 

G-4 Appendix G. Priority Conservation Areas 

This document continues on the next page.
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-5 

Figure 2. Priority Conservation Area Map Central Zone 
Willamette Valley Conservation Study 

G-6 Appendix G. Priority Conservation Areas 

This document continues on the next page.
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-7 

Figure 3. Priority Conservation Area Map North Zone 
Willamette Valley Conservation Study 

G-8 Appendix G. Priority Conservation Areas 

This document continues on the next page. 
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-9 

Table G1. Priority Conservation Areas. 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

Southern Section 

1. Upper 

Coyote Creek 750 Lane 

This small, riparian-focused PCA is located along the 

headwaters of Coyote Creek near the Territorial Highway 

north of the town of Crow. It contains riparian forests and 

shrublands and wetlands of conservation significance. 

2. Coast Fork 

Willamette 

River 

750 Lane 

Located along the Coast Fork of the Willamette River 

from the north end of Elijah Bristow State Park to the Fall 

Creek confluence, this PCA contains riparian forests and 

shrublands known to support conservation target species 

and wetlands of conservation significance. 

3. Middle Fork 

- Coast Fork 

Confluence/ 

Mount Pisgah 

6,500 Lane 

Large PCA that includes TNC’s Confluence Preserve, 

Buford Park, and Mount Pisgah. Mount Pisgah is an 

Audubon Society designated Important Bird Area. 

Targeted habitats include grasslands, oak savanna and 

woodlands, riparian forests, shrublands, and wetlands of 

conservation significance that support sensitive species 

and a regionally significant population of Bradshaw’s 

lomatium (LE). Riparian areas include anchor habitat and 

zones of influence. 

4. Lower 

McKenzie 

Oaks 

1,750 Lane 

Located east of Springfield and south of Highway 126, 

this PCA contains large stands of oak woodlands that 

support the slender-billed white-breasted nuthatch. 

5. Lower 

McKenzie 

River 

3,500 Lane 

Located along the Lower McKenzie River at Mohawk 

Creek, this PCA contains oak woodlands, and riparian 

forests and shrublands that are wetlands of conservation 

significance. 

6. West 

Eugene - 

Spencer 

Creek/Coyote 

Creek 

37,500 Lane 

Located west of Eugene, this very large PCA includes the 

ecologically significant West Eugene Wetlands and 

ODFW’s Fern Ridge Wildlife Area. The PCA abuts the 

Fern Ridge Reservoir, which is an Audubon Society 

designated Important Bird Area. The grasslands, oak 

savannas and woodlands, riparian forests and shrublands, 

and wetlands create rare habitats that support many 

sensitive species. ESA listed species include Willamette 

daisy (LE, CH), Fender’s blue butterfly (LE, CH), and 

Kincaid’s lupine (LT, CH). 

7. Coburg 

Hills (south) 5,250 Lane 

Located along the southern extent of the Coburg Hills, 

this PCA contains grasslands, oak savanna, and oak 

woodlands that are known to support conservation target 

species. Grassland habitats support Fenders blue butterfly 

(LE, CH). 
Willamette Valley Conservation Study 

G-10 Appendix G. Priority Conservation Areas 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

8. McKenzieWillamette 

Confluence / 

Harper's Bend 

Horseshoe Bar 

8,750 Lane 

Linn 

Large riparian-focused PCA located along the mainstem 

Willamette River north of Eugene. PCA contains riparian 

forests and shrublands, wetlands, zones of influence, cold 

points, and anchor habitat. McKenzie River Trust’s Green 

Island is located in this PCA. 

9. Coburg 

Hills (north) 6,500 Linn 

Located along the northern extent of the Coburg Hills, 

this PCA is a stronghold for Oregon vesper sparrow. It 

contains grasslands, oak savanna, and oak woodlands. 

The PCA also supports an important population of 

Kincaid’s lupine (LT). 

10. Calapooia 

Oak Savanna 250 Linn 

Small PCA located along the upper Calapooia River that 

includes McClun Wayside County Park. The PCA 

supports an important population of Willamette daisy 

(LE) and includes oak and riparian forest habitats. 

11. Ingram 

Island 2,500 Benton Linn 

Riparian-focused PCA located along the mainstem 

Willamette River between Corvallis and Eugene. 

Greenbelt Land Trust’s Harkins Lake property is located 

here. The PCA contains riparian forests and shrublands, 

wetlands of conservation significance, and important 

salmonid habitat elements (zones of influence, cold 

points, and anchor habitat). 

12. Sweet 

Home 

Lomatium Site 

750 Linn 

Small PCA, located south of Highway 20 near Sweet 

Home that includes the City’s Hobart Nature Reserve. 

The PCA includes an important population of Bradshaw’s 

lomatium (LE) and supports riparian forest and 

shrublands that are wetlands of conservation significance. 

13. Long TomWillamette 

Confluence 

6,750 Benton 

Linn 

PCA includes the Long Tom and Willamette River 

confluence along with the Snagboat Bend Unit of the 

W.R. Finley NWR. Targeted habitats include riparian 

forests and shrublands that support conservation target 

species, wetlands of conservation significance, and 

important salmonid habitat elements (zones of influence, 

cold points, and anchor habitat). 

14. Finley 

NWR /Muddy 

Creek 

13,750 Benton 

Large PCA centered on the W. L. Finley NWR, an 

Audubon Society designated Important Bird Area. The 

PCA includes many WVCS targeted species and habitats 

including grasslands, oak savanna and woodlands, 

riparian forests and shrublands, wetlands of conservation 

significance, and important populations of all 

conservation target species, including species listed under 

the ESA: streaked horned lark (LT, CH), Kincaid’s lupine 

(LT), Nelson’s checkermallow (LT), and Willamette 

daisy (LE, CH). The Refuge contains an experimental 

population of golden paintbrush (LT) and a 366-acre 
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-11 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

patch of wet prairie within the Willamette Floodplain 

Research Natural Area-the largest contiguous patch of 

wet prairie remaining in the valley. 

15. Oak Creek 

Prairie and 

Savanna 

500 Linn 

Small PCA along Oak Creek south of Lebanon and 

Highway 20, that supports a regionally significant 

population of Bradshaw’s lomatium (LE). 

16. East Slope 

Mary's Peak 1,750 Benton 

Located southwest of Corvallis along the Alsea Highway 

(Hwy 34) and Greasy Creek, the grasslands of this PCA 

support western meadowlark and important populations 

of Fender’s blue butterfly (LE) and Kincaid’s lupine 

(LT). Scattered oak woodlands occur along the hillslopes. 

17. 

StahlbuschJohn Smith 

Islands 

1,750 Benton 

Linn 

Riparian focused PCA along the mainstem Willamette 

River east of the Corvallis Airport. The PCA supports 

riparian forests and shrublands, wetlands of conservation 

significance, and important salmonid habitat elements 

(zones of influence, cold points, and anchor habitat). 

Central Section 

18. Bowers 

Rock-Truax 

Island 

2,250 Benton 

Linn 

Riparian focused PCA along the mainstem Willamette 

River between Albany and Corvallis that includes riparian 

forests and shrublands, wetlands of conservation 

significance, and important salmonid habitat elements 

(zones of influence, cold points, and anchor habitat). 

19. South 

Santiam 

(south) 

750 Linn 

Located along the South Santiam River south of Highway 

226, this PCA contains riparian forests and shrublands 

that are known to support conservation target species, 

wetlands of conservation significance, and zones of 

influence. 

20. Corvallis 

Area Forests 

and Balds 

(TCB-1) 

250 Benton 

Small PCA that is thought to have once provided habitat 

for the Taylor’s checkerspot butterfly (LE), and 

potentially could again. 

21. Golden 

Valley - 

Richardson 

Gap 

3,250 Linn 

Located just south of the Santiam River in the eastern part 

of the valley, this PCA supports grasslands, large patches 

of oak woodlands and scattered oak savanna. 

22. Corvallis 

Area Forests 

and Balds 

(south) 

18,750 Benton 

Located west and southwest of Corvallis, this large PCA 

supports many WVCS sensitive species targets and 

includes grasslands, oak savanna and woodlands, riparian 

forests and shrublands, and wetlands of conservation 

significance. The PCA supports important populations of 

Willamette daisy (LE, CH), Fender’s blue butterfly (LE, 

CH) and Kincaid’s lupine (LT, CH) and hosts one of 

Oregon’s two known extant populations of Taylor’s 

checkerspot butterfly (LE, CH). Jackson-Frazier 
Willamette Valley Conservation Study 

G-12 Appendix G. Priority Conservation Areas 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

Wetlands, Fitten Green Natural Area, Greenbelt Land 

Trust’s Bald Hill Farm and Lupine Meadows, and other 

conservation areas are located in this ecologically 

significant PCA. 

23. Lower 

Calapooia 

River 

750 Benton 

Linn 

Located just west of Albany, this riparian-focused PCA 

includes riparian forests, wetlands of conservation 

significance, and important fish habitat elements (cold 

points and anchor habitat). 

24. Corvallis 

Area Forests 

and Balds 

(TCB-2) 

250 Benton 

Small PCA that is thought to have once provided habitat 

for the Taylor’s checkerspot butterfly (LE), and 

potentially could again. 

25. Corvallis 

Area Forests 

and Balds 

(TCB-3) 

250 Benton 

This PCA is centered on Beazell Forest, which supports 

one of Oregon’s two known extant populations of 

Taylor’s checkerspot butterfly (LE). 

26. Corvallis 

Area Forests 

and Balds 

(TCB-4) 

250 Benton 

Small PCA that is thought to have once provided habitat 

for the Taylor’s checkerspot butterfly (LE), and 

potentially could again. 

27. South 

Santiam 

(north) 

1,250 Linn 

This riparian-focused PCA located along the South 

Santiam River north of Highway 226 includes the 

confluence with Crabtree Creek, riparian forests and 

shrublands, wetlands of conservation significance, and 

zones of influence. 

28. Corvallis 

Area Forests 

and Balds 

(TCB-5) 

250 Benton 

Small PCA that is thought to have once provided habitat 

for the Taylor’s checkerspot butterfly (LE), and 

potentially could again. 

29. Santiam 

Confluences 

(2) 

750 Marion 

Linn 

Located at the confluence of the North Santiam and the 

South Santiam, this PCA includes the confluence with 

Edgar Slough, riparian forests known to support yellow 

warbler, riparian shrublands, and wetlands of 

conservation significance. 

30. Santiam 

Confluences 

(3) 

750 Marion 

Linn 

Located along the North Santiam River just north of 

Jefferson Scio Drive, this PCA contains a large patch of 

riparian forest and shrubland that includes wetlands of 

conservation significance. An important population of 

Kincaid’s lupine is located in this PCA. 

31. 

Luckiamute 

River 

250 Polk 

Located in the northern section of Kings Valley west of 

Corvallis, this PCA includes oak woodlands and 

grasslands that once provided habitat for the Taylor’s 

checkerspot butterfly (LE), and potentially could again 

with proper management. 
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-13 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

32. Corvallis 

Area Forests 

and Balds 

(north) 

9,500 Benton 

Polk 

Located north and northeast of Corvallis, this PCA 

supports grasslands, oak savanna and woodlands, riparian 

forests and shrublands, wetlands, and listed species: 

Fender’s blue butterfly (LE) and Kincaid’s lupine 

(LT).Taylor’s checkerspot butterfly (LE) is thought to 

have once inhabited this area. The PCA includes 

ODFW’s E. E. Wilson Wildlife Area, an Audubon 

Society designated Important Bird Area and a stronghold 

for yellow-breasted chat. 

33. Santiam 

Confluences 

(1) 

750 Marion 

Linn 

Located along the Santiam River just east of I-5, this PCA 

contains a large patch of riparian forest that supports 

yellow-breasted chat, wetlands of conservation 

significance, and zones of influence. 

34. Santiam 

Confluences 

(4) 

3,250 Marion 

Linn 

Located along the North Santiam River south of the town 

of Marion, this PCA includes Wiseman Island and its 

significant stands of riparian forests and shrublands that 

support both yellow warbler and yellow-breasted chat. 

Also contains large wetlands of conservation significance. 

35. 

Luckiamute 

River (TCB) 

250 Polk 

Small PCA that is thought to have once provided habitat 

for the Taylor’s checkerspot butterfly (LE), and 

potentially could again. 

36. Santiam 

Confluences 

(5) 

2,250 Marion 

Linn 

Located along the North Santiam River south of Stayton, 

this PCA includes large patches of riparian forest and 

shrublands that support targeted species and wetlands of 

conservation significance. 

37. Upper 

Lukiamute 

(FBB) 

250 Polk 

Small PCA that is thought to have once provided habitat 

for the Taylor’s checkerspot butterfly (LE), and 

potentially could again. 

38. Habeck 

Oaks (south) 1,250 Polk 

Located south of the Monmouth Highway east of the 

intersection with Kings Valley Highway (Hwy 223), this 

PCA includes portions of Cooper Creek and includes 

large stands of oak woodlands and oak savanna known to 

support targeted species. Riparian forests occur along 

Cooper Creek. 

39. Beaver 

Creek-Upland 

Larkspur 

250 Marion 

This small PCA located east of Sublimity contains 

grasslands that support important populations of 

Willamette daisy (LT, CH) and Bradshaw’s lomatium 

(LT). 

40. Habeck 

Oaks (mid) 750 Polk 

Located north of the Monmouth Highway (Hwy 194) and 

east of Kings Valley Highway (Hwy 223), this PCA 

includes oak woodlands and savanna that support western 

bluebird and slender-billed white-breasted nuthatch. 

41. Willamette 

Mainstem 1,500 Marion Polk 

This riparian-focused PCA is along the Willamette River 

just west of Ankeny NWR. It contains riparian forests and 
Willamette Valley Conservation Study 

G-14 Appendix G. Priority Conservation Areas 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

Section 6 

Connectivity 

Area 

shrublands, wetlands of conservation significance, and 

zones of influence. 

42. Ankeny 

NWR-Salem 

Hills 

28,000 Marion 

Polk 

PCA includes the grasslands, riparian forests and 

shrublands, and wetlands of the Ankeny NWR, an 

Audubon Society designated Important Bird Area. PCA 

also includes the Santiam and Little Luckiamute 

confluences with the Willamette. Oak savanna and 

woodlands on the Salem Hills support an important 

slender-billed white-breasted nuthatch population. 

Ankeny NWR supports Nelson’s checkermallow (LT) 

and streaked horned lark (LT, CH). Salmonid habitat 

elements occur along the Willamette and Santiam rivers 

(zones of influence, cold points, and anchor habitat). 

43. Black 

Rock (TCB) 250 Polk 

Small PCA that is thought to have once provided habitat 

for the Taylor’s checkerspot butterfly (LE), and 

potentially could again. 

44. Habeck 

Oaks (north) 4,500 Polk 

Located southeast of Dallas and west of Kings Valley 

Highway (Hwy 223), this PCA includes large patches of 

oak woodlands and savanna known to support western 

bluebird and slender-billed white-breasted nuthatch. 

45. Minto 

Island 3,500 Marion Polk 

This PCA includes both Hayden Island and Minto Island 

with its ~1,200-acre Minto-Brown Island Park. Riparian 

forests and shrublands are known to support targeted 

species. The islands also include wetlands of conservation 

significance, and important fish habitat elements (zones 

of influence and anchor habitat). 

Northern Section 

46. Baskett 

Slough NWR 

(east) 

7,000 Polk 

PCA centered on Baskett Slough NWR, an Audubon 

Society designated Important Bird Area. Grasslands, oak 

savanna and woodlands support western meadowlark, 

Oregon vesper sparrow, western bluebird, and slenderbilled nuthatch. Baskett Slough NWR prairies support the 

largest population of the endangered Fender’s blue 

butterfly (LE, CH) within its range along with Kincaid’s 

lupine (LT), Willamette daisy (LE, CH), and streaked 

horned lark (LT, CH). The PCA provides important 

migratory bird wintering areas and stopover sites, and 

includes the Mud Slough area east of the Refuge which is 

an Audubon Society designated Important Bird Area. 

47. Mill Creek 500 Polk 

Located along Mill Creek at Highway 22, grasslands of 

this small PCA support an important population of 

Fender’s blue butterfly (LE, CH) and Kincaid’s lupine 

(LT, CH). 
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-15 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

48. Baskett 

Slough NWR 

(west) 

3,000 Polk 

Located west of Baskett Slough NWR, north of Highway 

22, and east of Van Well Road, this PCA includes 

grasslands and oak woodlands known to support targeted 

conservation species such as western meadowlark, 

Oregon Vesper sparrow, and slender-billed whitebreasted nuthatch. 

49. Eola Hills 8,000 Polk 

Located in the Eola Hills east of Baskett Slough NWR, 

this PCA contains large patches of oak woodlands that 

support targeted species such as the slender-billed whitebreasted nuthatch and western bluebird. Grasslands 

support western meadowlark. 

50. Grand 

Island (south) 13,500 Marion Yamhill 

This large, riparian-focused PCA is located west of 

Kaiser and extends north (downstream) along the 

Willamette River to include Willamette Mission Park and 

the confluence of Lambert Slough. The PCA includes 

large patches of riparian forests and shrublands that are 

known to support targeted conservation species. Also 

includes wetlands of conservation significance and 

important salmonid habitat elements (zones of influence, 

cold points, and anchor habitat). 

51. Red Prairie 1,250 Polk 

Located north of Highway 22 and east of Red Prairie 

Road, this PCA contains grasslands and oak woodlands 

known to support western meadowlark, Oregon vesper 

sparrow, and slender-billed white-breasted nuthatch. 

52. Willamina 

Oaks South 3,000 Polk 

Located at the junction of Highways 18 and 22, this PCA 

includes grasslands and oak savanna and woodlands. A 

large complex of protected grasslands and oak woodlands 

is located within this PCA which includes TNC’s Noble 

Oaks Reserve. 

53. Willamina 

Oaks North 1,250 Yamhill 

Located north of Highway 18 near the intersection with 

Highway 22, this PCA of oak savanna and woodlands 

supports important populations of Fender’s blue butterfly 

and Kincaid’s lupine. 

54. Rock 

Creek 1,250 Clackamas 

Riparian-focused PCA located southwest of Mollala, just 

west of Highway 213. Riparian forests support targeted 

species. PCA also includes riparian shrublands and 

wetlands of conservation significance. 

55. South Fork 

Yamhill River 1,000 Yamhill 

Riparian-focused PCA located west of Amity and north 

of Highway 153 with riparian forests that support targeted 

species. PCA also includes wetlands of conservation 

significance. 

56. Yamhill 

Oaks 17,750 Yamhill 

Large PCA located in Yamhill County north of Highway 

18 that contains large patches of oak woodlands known to 

support targeted species. PCA also includes grasslands, 
Willamette Valley Conservation Study 

G-16 Appendix G. Priority Conservation Areas 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

oak savanna, riparian forests and shrublands known to 

support targeted species. Grasslands and savanna support 

important populations of Fender’s blue butterfly (LE, 

CH) and Kincaid’s lupine (LT, CH). TNC’s Yamhill 

Oaks Reserve is in this PCA. 

57. Mollala 

River and 

Grasslands 

8,750 Clackamas 

PCA includes grasslands known to support western 

meadowlark and Oregon vesper sparrow. Riparian forests 

and wetlands of conservation significance occur along the 

river. 

58. Grand 

Island (north) 2,250 Yamhill 

Located west of St. Paul along the mainstem Willamette 

River, this riparian-focused PCA includes riparian forests 

known to support targeted species. The PCA also includes 

wetlands of conservation significance and zones of 

influence. 

59. Champoeg 1,000 Yamhill 

Spanning both sides of the Willamette River, this PCA 

includes Champoeg State Park and includes riparian 

forests and shrublands. Oak woodlands known to support 

the slender-billed white-breasted nuthatch are found 

along the hillsides. 

60. Trapist 

Abbey 2,250 Yamhill 

Located north of the town of Lafayette, this PCA includes 

the oak woodlands of Our Lady of Guadalupe Trappist 

Abbey and other nearby woodlands. A conservation 

easement protects the Abby’s oak habitat. 

61. PuddingMollala 

Confluence 

5,250 Clackamas 

This PCA includes the lower reach of the Pudding River, 

its confluence with the Molalla River, and the Molalla 

and Willamette River confluence. Molalla River State 

Park is located here. Large riparian forests and shrublands 

support conservation target species. PCA includes large 

wetlands of conservation concern and anchor habitat. Oak 

woodlands occur along the south-facing hills north of the 

Willamette River. 

62. Oak Ridge/ 

Moore's 

Valley (east) 

2,250 Yamhill 

Located west of the Oak Ridge Road and Fairdale Road 

intersection, this PCA supports large patches of oak 

woodlands. Grasslands support an important population 

of Fender’s blue butterfly (LE, CH) and Kincaid’s lupine 

(LT, CH). 

63. Oak Ridge/ 

Moore's 

Valley (west) 

750 Yamhill 

Located just west of PCA 62, this PCA includes large 

patches of oak woodlands. The North Yamhill River 

flows through this PCA. 

64. Clackamas 

River 6,250 Clackamas 

Located west of Highway 211 and north of Estacada, this 

PCA includes grasslands and riparian forests known to 

support conservation target species including western 

meadowlark and Oregon vesper sparrow. Wetlands of 

conservation significance occur in the riparian forests. 
Willamette Valley Conservation Study 

Appendix G. Priority Conservation Areas G-17 

Priority 

Conservation 

Area 

Size 

(acres) County Primary Conservation Targets Present 

65. Mount 

Richmond 1,250 Yamhill 

This PCA is located along Turner Creek near its 

confluence with the North Santiam River. Grasslands 

support a population of Fender’s blue butterfly (LE). Oak 

woodlands occur along the hillsides. 

66. Tualatin 

River NWR 8,750 Washington 

PCA is centered on the Tualatin River NWR, an Audubon 

Society designated Important Bird Area. The PCA 

contains grasslands, oak woodlands, riparian forests, and 

wetlands of conservation significance. 

67. Tualatin 

River 1,500 Washington 

Located upstream of the Tualatin River NWR, this PCA 

includes the riparian habitats of the Tualatin River and 

Burris and Christensen creeks, which are wetlands of 

conservation significance. 

68. Tualatin 

Headwaters 1,000 Washington 

Located south of the town of Cherry Grove along the 

headwaters of the Tualatin River, this PCA includes 

riparian forests and shrublands known to support 

conservation target species. Oak woodlands occur along 

the hillsides. 

69. Wapato 

Lake NWR/ 

Ribbon Ridge 

12,500 Washington 

Yamhill 

This PCA is centered on the wetland habitats of the 

Wapato Lake NWR and the oak woodlands of Ribbon 

Ridge. Wapato Lake NWR contains wetlands of 

conservation significance. 

70. Scoggins 

Valley 1,250 Washington 

Located west and south of Henry Hagg Lake, the 

grassland habitats of this PCA support important 

populations of Kincaid’s lupine (LT) and the 

northernmost known population of Fender’s blue 

butterfly (LE). 

71. Jackson 

Bottoms Area 6,500 Washington 

This PCA, located in the mid- Tualatin River watershed, 

includes the 650-acre Jackson Bottom Wetlands Preserve, 

an Audubon Society designated Important Bird Area. The 

PCA includes riparian forests and shrublands and 

wetlands of conservation significance. 

72. Gales 

Creek 1,250 Washington 

Located northwest of Forest Grove along Gales Creek, 

this PCA includes the confluence with Kelly Creek, 

riparian forests and shrublands, and wetlands of 

conservation significance. 

73. Sandy 

River Delta 6,250 Multnomah 

PCA includes the Sandy River Delta and the riparian 

habitats of the lower Sandy River to Metro’s Oxbow 

Regional Park. The Delta is located near Troutdale at the 

confluence of the Sandy and Columbia rivers. The US 

Forest Service manages the delta. The delta includes 

grasslands, riparian forests and shrublands that support 

conservation target species as well as wetlands of 

conservation significance. 

 
Willamette Valley Conservation Study 

G-18 Appendix G. Priority Conservation Areas 

74. Banks 

Swamp 1,500 Washington 

Banks Swamp (also known as the Killin Wetlands) is an 

Audubon Society designated Important Bird Area. The 

PCA is located along Highway 6 west of Banks and 

contains an important remnant of the Willamette Valley 

scrub-shrub marsh present before settlement. The PCA 

contains riparian forests and shrublands that support 

yellow warbler and large wetlands of conservation 

significance. 

75. Smith and 

Bybee 

Wetlands 

2,250 Multnomah 

Located near the confluence of the Willamette and 

Columbia rivers within the City of Portland, this PCA is 

centered on Metro’s 2,000-acre Smith and Bybee 

Wetlands Natural Area. The PCA includes riparian 

forests and shrublands, wetlands of conservation 

significance, and seasonal mud-flat habitats. It provides 

important migratory bird wintering area and stopover site. 

76. McKay 

Creek - Red 

Slide Hill 

2,500 Washington 

Located along McKay Creek north of the city of North 

Plains, this riparian-focused PCA also includes the East 

Fork McKay Creek. Riparian forests along the creeks 

create large wetlands of conservation significance. 

LE = Listed Endangered; LT = Listed Threatened; CH = Critical Habitat (Designated) 

Wetland/ 

USFWS 
Willamette Valley Conservation Study 

Appendix H. GAP Analysis H-1 

Appendix H. Gap Analysis 

Introduction 

The purpose of a gap analysis is to compare priority areas for conservation against the amount and 

distribution of protected lands within the planning area. Priority areas that are not adequately 

represented in the portfolio of protected lands represent a “gap” in the conservation area network 

(Margules and Pressey 2000, Groves 2003). Identifying gaps is an important step in systematic 

conservation planning. The purpose of the gap analysis conducted for this study was to compare the 

amount and distribution of protected lands within PCAs against the habitat objective, to determine if 

a given objective is satisfied by the current configuration of protected lands. The difference between 

what is already protected and the habitat objective represents a gap in meeting WVCS conservation 

objectives. 

In order to make sure we were working with the most up-to-date information, we contracted with the 

Institute for Natural Resources (INR) to update the Protected Area Database of the United States 

(PAD-US). Administered by the U.S. Geologic Survey, PAD-US is the official inventory of 

protected open space in the United States. INR contacted federal, state, and local agencies and land 

trusts active in the Willamette Valley, to update their inventory of protected lands and their gap 

status. Reporting is voluntary and land protection is ongoing, so there cannot be 100 percent 

assurance that all protected lands are included. 

We used the updated data in completing the gap analysis. PAD-US data includes a “gap status” of 

protected lands. The gap status indicates how the lands are being managed for conservation purposes. 

A gap analysis typically only considers lands in gap statuses 1 and 2, which identify the lands in 

permanent protection from conversion with a mandated management plan, to maintain a primarily 

natural state the lands, however, may be subject to practices that suppress natural disturbances such 

as wildfire. Gap status 3 lands have permanent protection, but may be subject to extractive activities 

such as logging or mining, and as such, do not convey an appropriate level of protection needed to 

meet the Service’s conservation goals for the valley. We used gap status 1 and 2 lands in this 

analysis, but also included some areas that were not gap status 1 or 2, but are public lands that 

contain quality habitat, are of sufficient size, and are governed by management plans that protect 

wildlife values. 

Sustaining a diversity of healthy populations over time requires conserving a sufficient variety and 

amount of habitat and building an ecologically-connected network of conservation areas to allow the 

movement of species in response to climate change. Adequate protection, therefore, cannot be 

measured just by the amount of acres under conservation status anywhere in the valley, but rather by 

securing the habitat objectives—the number, size, and distribution of habitat patches under some 

form of conservation status that prioritizes management for the conservation target species. 

The discussion, just as the population and habitat objectives, is broken-down into the northern part of 

the valley (north of Salem, PCAs 46-76), the central part of the valley (Salem to Corvallis, PCAs 18-

45), and the southern valley (south of Corvallis PCAs 1-17). 

Grasslands 

North 

In the northern part of the valley, the objective is to manage 2,813 acres of core grassland habitat for 

western meadowlark, Oregon vesper sparrow, and other grassland dependent species. This habitat 

should be distributed across the northern valley in order to support three subpopulations of western 
Willamette Valley Conservation Study 

H-2 Appendix H. GAP Analysis 

Streaked horned lark/© Joe Staff 

meadowlark (one medium subpopulation 

[20-30 breeding pairs on 938 acres], and 

two small subpopulations [10-20 breeding 

pairs on 563 acres each]). 

About 1,970 acres of grassland habitat 

within the northern PCAs is currently 

protected. This represents about 70 percent 

of the total objective, but these grasslands 

are found primarily in only two PCAs: 

Baskett Slough National Wildlife Refuge 

(Refuge) (east) [PCA 46], which has the 

vast majority of protected grasslands (1,740 acres) and represents about 89 percent of the protected 

grasslands; and Tualatin River National Wildlife Refuge [PCA 67] (207 acres). A third site has less 

than 20 acres of protected grasslands. The habitat at Baskett Slough Refuge meets the objective for 

the single medium core patch. No other area has sufficient protected grasslands to satisfy the small 

core patch objective. 

Important PCAs for additional grassland conservation include additional areas around the Baskett 

Slough Refuge (east and west) [PCAs 46 and 48] to benefit from a potential source population of 

western meadowlarks on the Refuge, Eola Hills [PCA 49], and the Molalla River and Grasslands 

[PCA 57]. In the Molalla area, establishing a protected core habitat patch could be an important step 

in recovering these species in the northern part of the valley. The Yamhill Oaks [PCA 56] has over 

2,000 acres of grassland habitat, but there are no recent documented occurrences of western 

meadowlark or Oregon vesper sparrow so this area is not an immediate priority area for grassland 

birds. 

Center 

In the central part of the valley, the objective is for 7,211 acres of core grassland habitat be managed 

for western meadowlark, vesper sparrow, streaked horned lark, and other grassland dependent 

species The habitat should be distributed in order to support seven subpopulations, comprised of one 

large subpopulation of western meadowlark (30-40 breeding pairs on 1,313 acres), two medium 

subpopulations (20-30 breeding pairs on 938 acres each), and four small subpopulations (10-20 

breeding pairs on 563 acres each). 

There are currently approximately 2,900 acres of protected grassland habitat within the central PCAs, 

or about 40 percent of the overall objective. These are found in only two PCAs: 2,434 acres at 

Ankeny NWR-Salem Hills [PCA 42] and 469 acres at Corvallis Area Forests and Balds (south) [PCA 

22]. Ankeny NWR/Salem Hills [PCA 42] has almost 87 percent of the protected grassland habitat 

within the PCAs in this part of the valley. 

Protected lands within Ankeny NWR-Salem Hills [PCA 42] meet the habitat objective for the large 

core habitat patch. Protected areas in the Corvallis Area Forests and Balds (south) [PCA 22] and the 

Corvallis Area Forests and Balds (north) [PCA 32] provide building blocks for achieving additional 

habitat objectives for either small or medium core patches. 

Priority areas for grassland birds include Ankeny NWR-Salem Hills [PCA 42] and Corvallis Area 

Forests and Balds (south and north) [PCA 22 and PCA 32]. 
Willamette Valley Conservation Study 

Appendix H. GAP Analysis H-3 

South 

In the southern part of the valley, the objective is for 8,745 acres of core grassland habitat to be 

managed for western meadowlark, vesper sparrow, streaked horned lark, and other grasslanddependent species. This habitat should be distributed in order to support 9 subpopulations, consisting 

of 1 large subpopulation of western meadowlark (30-40 breeding pairs on 1,313 acres acres), 2 

medium subpopulations (20-30 breeding pairs on 938 acres each), and 6 small subpopulations (10-20 

breeding pairs on 563 acres each). 

There are currently approximately 3,147 acres of protected grassland habitat within the southern 

PCAs, or about 36 percent of the overall objective. These protected grasslands occur in 4 of the 

southern PCAs. 

Finley NWR/Muddy Creek [PCA 14] has the largest block of protected grasslands (2,544 acres) 

which is about 93 percent of the total protected. Two other PCAs each have less than 400 acres of 

protected grasslands. These are West Eugene-Spencer Creek/Coyote Creek [PCA 6] (399 acres); 

Coburg Hills (south) [PCA 7] (157) acres; and Middle Fork-Coast Fork Confluence/Mount Pisgah 

[PCA 3] (47 acres). 

Finley NWR/Muddy Creek [PCA 14] meets the habitat objective for the large core habitat patch and 

is the only area that meets any of the habitat objectives. 

Important PCAs for additional grassland conservation include Finley NWR/Muddy Creek [PCA 14]; 

West Eugene-Spencer Creek/Coyote Creek [PCA 6]; Middle Fork-Coast Fork Confluence/Mount 

Pisgah [PCA 3]; and Coburg Hills (north) [PCA 9]. 

Oak Savanna 

Very little oak savanna remains in the valley today and very little of that is protected. 

North 

In the northern portion of the valley, the objective is for 1,500 acres of core oak savanna habitat to be 

managed for the western bluebird and other oak savanna wildlife. This acreage should be distributed 

in order to support 10 subpopulations of western bluebird, consisting of 1 large subpopulation (20-30 

breeding pairs on 263 acres); 3 medium subpopulations (20-30 breeding pairs on 188 acres each); 

and 6 small subpopulations (10-20 breeding pairs on 113 acres each) 

Very little oak savanna is currently protected in the north part of the valley with protected areas 

found in only two PCAs to any extent: Eola Hills [PCA 49] has 105 acres and Baskett Slough NWR 

(east) [PCA 46] has 32 acres. 

While no PCA has sufficient protected oak savanna to meet a habitat objective, Eola Hills [PCA 49] 

is close to meeting the requirements for a small core habitat patch. 

Important PCAs for additional oak savanna conservation include Baskett Slough NWR (east) [PCA 

46] and Eola Hills [PCA 49]. Yamhill Oaks [PCA 56] has over 1,000 acres of mapped oak savanna, 

by far the most of any PCA, but no observations of western bluebird have been recorded there over 

the past five years, making oak savanna conservation in this PCA a somewhat lower priority. 

Center 

In the central part of the Willamette Valley, the objective is for 1,763 acres of core oak savanna 

habitat to be managed for the western bluebird and other oak savanna wildlife. This habitat should be 

distributed in order to support 11 subpopulations of western bluebird consisting of 2 large 
Willamette Valley Conservation Study 

H-4 Appendix H. GAP Analysis 

subpopulations (30-40 breeding pairs on 263 acres each); 3 medium subpopulations (20-30 breeding 

pairs on 188 acres each); and 6 small subpopulations (10-20 breeding pairs on 113 acres each) 

Only 2 central PCAs have any protected oak savanna habitat. Corvallis Area Forests and Balds 

(north) [PCA 32] has 234 acres and Corvallis Area Forests and Balds (south) [PCA 22] has 56 acres. 

Habitat protected in ODFW’s E.E. Wilson Wildlife Area within the Corvallis Area Forests and Balds 

(north) [PCA 32] satisfies the acreage objective for a small core habitat patch. 

Important PCAs for additional oak savanna conservation include Ankeny NWR-Salem Hills [PCA 

42]; Corvallis Area Forests and Balds (south [PCA 22] and north [PCA 32] sections); Golden Valley 

– Richardson Gap [PCA 21]; and Habeck Oaks (south) [PCA 38]. 

South 

In the southern part of the valley, the objective is for 1,388 acres of core oak savanna habitat to be 

managed for the western bluebird and other oak savanna wildlife. The habitat should be distributed in 

order to support 9 subpopulations of western bluebird, consisting of 1 large subpopulation (20-30 

breeding pairs on 263 acres); 3 medium subpopulations (20-30 breeding pairs on 188 acres each); 

and 5 small subpopulations (10-20 breeding pairs on 113 acres each). 

In the southern part of the valley, protected oak savanna occurs in only 3 PCAs. The greatest amount 

is 132 acres in the Coburg Hills (south) [PCA 7]: followed by 55 acres in the Finley NWR/Muddy 

Creek [PCA 14]: and 24 acreas in the West Eugene-Spencer Creek/Coyote Creek [PCA 6]. 

Habitat protected in the Coburg Hills (south) [PCA 7] satisfies the objectives needed for a small core 

habitat patch. 

Important PCAs for additional oak savanna conservation include Finley NWR/Muddy Creek [PCA 

14]; West Eugene-Spencer Creek/Coyote Creek [PCA 6]; and Coburg Hills (north [PCA 9] and south 

[PCA 7]). 

Oak Woodlands 

North 

In the northern section of the valley, the objective is for 16,500 acres of core oak woodland habitat to 

be managed for the slender-billed white-breasted nuthatch, and other oak woodland wildlife. Habitat 

should be distributed in order to support 35 subpopulations of the slender-billed white-breasted 

nuthatch, consisting of 5 large subpopulations (50 breeding pairs or more on 900 acres each), 10 

medium subpopulations (30-50 breeding pairs on 600 acres each), and 20 small subpopulations (10-

30 breeding pairs on 300 acres each). 

There are approximately 2,617 acres of protected oak woodland habitat in the northern PCAs, 

representing about 16 percent of the habitat objective. Three PCAs each have more than 200 acres of 

protected habitat: Eola Hills [PCA 49] has 1,249 acres; Trappist Abbey [PCA 60] has 495 acres; and 

Baskett Slough NWR (east) [PCA 46] has 430 acres. Willamina Oaks South [PCA 52] with 151 acres 

and Yamhill Oaks [PCA 56] with 186 acres contribute to the total. 

Eola Hills [PCA 49] satisfies the habitat objectives for a large core habitat patch. Trapist Abbey 

[PCA 60] satisfies the habitat objectives for a medium core patch although there are no recent 

documented occurrences of the slender-billed white-breasted nuthatch at the Abbey. Baskett Slough 

NWR (east) [PCA 46] satisfies the objectives for a small core patch. 
Willamette Valley Conservation Study 

Appendix H. GAP Analysis H-5 

Priorities for additional conservation include the Yamhill Oaks [PCA 56], Eola Hills [PCA 49], 

Trapist Abbey [PCA 60], Baskett Slough NWR (east [PCA 46] and west [PCA 48]), Willaminia 

Oaks South [PCA 52], and Wapato Lake NWR/Ribbon Ridge [PCA 69]. 

Center 

In the central part of the valley, the objective is for 16,500 acres of core oak woodland habitat to be 

managed for the slender-billed white-breasted nuthatch and other oak woodland wildlife. This habitat 

should be distributed in order to support 35 subpopulations, consisting of 5 large subpopulations (50 

pairs or more on 900 acres each); 10 medium subpopulations (30-50 pairs on 600 acres each); and 20 

small subpopulations (10-30 pairs on 300 acres each) 

There are about 555 acres of protected oak woodland habitat in the central part of the valley, which 

accounts for just a little over 3 percent of the habitat objective. These acres occur in just 4 PCAs. 

Corvallis Area Forests and Balds (south) [PCA 22] with 462 acres is the only PCA with greater than 

300 acres of protected oak woodland. None have greater than 600 acres. There are two PCAs that 

each have less than 50 acres: Ankeny NWR-Salem Hills [PCA 42] has 50 acres; and Corvallis Area 

Forests and Balds (north) [PCA 32] has 40 acres. 

Protected areas within Corvallis Area Forests and Balds (south) [PCA 22] meet the objectives for a 

small core habitat patch. Protected oak woodlands occur on Fitton Greem and at Bald Hill Farm. 

Efforts to connect these habitats could result in a medium or large core habitat patch. 

Important PCAs for additional oak woodland conservation include Corvallis Area Forests and Balds 

(south [PCA 22] and north [PCA 32]), Ankeny NWR-Salem Hills [PCA 42], Habeck Oaks (mid) 

[PCA 40], and Golden Valley–Richardson Gap [PCA 21]. 

South 

In the southern part of the valley, the objective is for 16,200 acres of core oak woodland habitat to be 

managed for the slender-billed white-breasted nuthatch, and other oak woodland wildlife. Habitat 

should be distributed in order to support 34 subpopulations of slender-billed white-breasted nuthatch, 

consisting of 5 large subpopulations (50 pairs or more on 900 acres each), 10 medium subpopulations 

(30-50 pairs on 600 acres each), and 19 small subpopulations (10-30 pairs on 300 acres each). 

There are about 1,620 acres of protected oak woodland habitat in the southern PCAs of the valley. 

There are only two protected areas within the PCAs with greater than 400 acres of protected oak 

woodland habitat in each: Finley NWR/Muddy Creek [PCA 14] has 708 acres and Coburg Hills 

(south) [PCA 7] has 491 acres. Other areas contributing oak woodland habitat include West EugeneSpencer Creek/Coyote Creek [PCA 6] has 230 acres, and Middle Fork-Coast Fork Confluence/Mount 

Pisgah [PCA 3] has 189 acres. An additional PCA has less than 5 acres of protected oak woodland. 

Protected habitat within Finley NWR/Muddy Creek [PCA 14] satisfies the habitat requirement for a 

medium core patch and Coburg Hills (south) [PCA 7] satisfies the requirement for a small core patch. 

Priority areas for additional oak woodland conservation include West Eugene-Spencer Creek/Coyote 

Creek [PCA 6]; Finley NWR/Muddy Creek [PCA 14]; Lower McKenzie River [PCA 5]; and Middle 

Fork-Coast Fork Confluence/Mount Pisgah [PCA 3]. 

Riparian Forest 

North 

In the northern section, the objective is for 5,400 acres of core riparian forest habitat to be managed 

for the yellow warbler and other riparian forest wildlife. Habitat should be distributed in order to 
Willamette Valley Conservation Study 

H-6 Appendix H. GAP Analysis 

support 19 subpopulations, consisting of 3 large subpopulations (540 acres each), 5 medium 

subpopulations (360 acres each), and 11 small subpopulations (180 acres each). 

Approximately 765 acres of protected riparian forest occur within the northern PCAs. Three PCAs 

have over 100 protected acres each: Tualatin River NWR [PCA 66] has 209 acres; the Sandy River 

Delta [PCA 73] has 962 acres; and the Banks Swamp [PCA 74] has a little over 100 acres. 

The Sandy River Delta [PCA 73] is comprised of two sections: the Wild and Scenic River section 

upstream of the delta, and the delta itself. Protected areas within the delta meet the requirements for a 

large core patch, and protected areas in the Wild and Scenic River section meet the requirements for 

a small subpopulation. While the delta does not have GAP 1 or 2 status according to PAD-US, it is 

managed by the Sandy River Management Plan (USFS 1995), which proposes adequate management 

of the delta’s habitat values to consider it protected. Protected riparian forests on the delta meet the 

requirements for a large core habitat patch. 

Tualatin River NWR [PCA 66] meets the criteria for a second small core patch. 

Priority PCAs for additional riparian forest conservation include Grand Island (south) [PCA 50], 

which has less than 3 of its 2,300 acres of riparian forest in conservation status; Pudding-Mollala 

Confluence [PCA 61]; Tualatin River NWR [PCA 66]; and Mollala River and Grasslands [PCA 57]. 

Center 

In the central section of the valley, the objective is for 4,860 acres of core riparian forest habitat to be 

managed for the yellow warbler and other riparian forest wildlife. This habitat should be distributed 

in order to support 18 yellow warbler subpopulations, consisting of 2 large subpopulations (540 acres 

each), 5 medium subpopulations (360 acres each), and 11 small subpopulations (180 acres each). 

Approximately 1,120 acres of riparian forest are protected within the central PCAs, representing 

about 23 percent of the objective. Ankeny NWR-Salem Hills [PCA 42] has 574 acres, and is the only 

PCA with more than 180 protected acres. Other PCAs with protected riparian forest of any 

consequence, include Corvallis Area Forests and Balds (south) [PCA 22] with 139 acres; and 

Corvallis Area Forests and Balds (north) [PCA 32] and Santiam Confluences (5) [PCA 36] each with 

just under 100 acres. Three PCAs have from 50 to 80 acres protected each: Bowers Rock-Truax 

Island [PCA 18]; Minto Island [PCA 45]; and Santiam Confluences (2) [PCA 29]. 

Protected riparian forest in Ankeny NWR-Salem Hills [PCA 42] meets the objective for 1 of the 2 

large core habitat patches. No other PCA has a sufficient quantity of protected riparian forest to meet 

any other habitat objective. 

Priority areas for additional conservation include: Ankeny NWR-Salem Hills [PCA 42]; Bowers 

Rock-Truax Island [PCA 18]; Corvallis Area Forests and Balds (north [PCA 32] and south [PCA 

22]); Minto Island [PCA 45]; and the Santiam Confluences PCAs [PCAs 29, 30, 34, and 36]. 

South 

In the southern section of the valley, the objective is for 4,860 acres of core riparian forest habitat to 

be managed for the yellow warbler and other riparian forest wildlife. Habitat should be distributed to 

support 18 subpopulations of yellow warbler, consisting of 2 large subpopulations (540 acres each), 5 

medium subpopulations (360 acres each), and 11 small subpopulations (180 acres each). 

There are approximately 2,520 acres of protected riparian forest habitat within the southern PCAs, or 

52 percent of the habitat objective. There are four PCAs with greater than 180 acres of protected 

bottomland hardwood forests each: Finley NWR/Muddy Creek [PCA 14] has about 990 acres; West 

Eugene-Spencer Creek/Coyote Creek [PCA 6] has 888 acres; Middle Fork-Coast Fork 
Willamette Valley Conservation Study 

Appendix H. GAP Analysis H-7 

Confluence/Mount Pisgah [PCA 3] has 242 acres; and McKenzie-Willamette Confluence/Harper’s 

Bend-Horseshoe Bar [PCA 8] has 230 acres. 

Finley NWR/Muddy Creek [PCA 14] has sufficient protected riparian forest to meet the objectives 

for 1 large core habitat patch. Protected habitat distribution in West Eugene-Spencer Creek/Coyote 

Creek [PCA 6] satisfy the requirements for 1 medium and 1 small core habitat patches. McKenzieWillamette Confluence/Harper’s Bend-Horseshoe Bar [PCA 8] and Middle Fork-Coast Fork 

Confluence/Mount Pisgah [PCA 3] meet the objectives for 2 additional small core patches. 

Priority PCAs for riparian forest conservation include: Finley NWR/Muddy Creek [PCA 14]; 

McKenzie-Willamette Confluence/Harper’s Bend-Horseshoe Bar [PCA 8]; West Eugene-Spencer 

Creek/Coyote Creek [PCA 6]; Middle Fork-Coast Fork Confluence/Mount Pisgah [PCA 3]; Long 

Tom–Willamette Confluence [PCA 13]; and Ingram Island [PCA 11]. 

Riparian Shrubland 

North 

In the northern section of the valley, the objective is for 1,650 acres of core riparian shrubland habitat 

to be managed for the yellow-breasted chat and other riparian shrubland wildlife. Habitat should be 

distributed to support 7 subpopulations, consisting of 450 acres for 1 large subpopulation, 300 acres 

each for 2 medium subpopulations, and 150 acres each for 4 small subpopulations. Approximately 

238 acres of riparian shrubland have been protected within the northern PCAs, representing 14 

percent of the objective. Metro’s Smith and Bybee Wetlands [PCA 75] with about 630 acres of 

shrubland and the Sandy River Delta [PCA 73] with 216 acres have the most shrubland habitat in the 

north part of the valley. Banks Swamp [PCA 74] has 90 acres of protected shrubland. Banks Swamp 

(also known as Kilian Wetlands) is recognized by the Audubon Society as an Important Bird Area. 

Metro has been actively engaged in protecting this important site. 

Three other PCAs have from 20-45 acres of protected shrubland habitat: Tualatin River NWR [PCA 

66] has 43 acres; Pudding-Mollala Confluence [PCA 61] has 21 acres; and Trapist Abbey [PCA 60] 

has 20 acres protected. 

Smith and Bybee Wetlands [PCA 75] which does not have GAP 1 or 2 status according to PAD-US, 

is managed by the Smith and Bybee Wetlands Natural Area: Comprehensive Natural Resource Plan 

(Metro 2012) which conveys adequate protection of the resource values and is considered to meet the 

requirements for a large core habitat patch. 

Protected habitat on the Sandy River Delta [PCA 73] satisfies the requirements for a small core 

patch. 

Important PCAs for additional riparian shrubland conservation include Grand Island (south) [PCA 

50] where almost none of the mapped 636 acres of riparian shrubland is protected, Pudding-Mollala 

Confluence [PCA 61]; Tualatin River NWR [PCA 66]; and Mollala River and Grasslands [PCA 57]. 

Center 

In the central section of the valley, the objective is for 1,950 acres of core riparian shrubland habitat 

to be managed for yellow-breasted chat and other riparian shrubland wildlife, that is distributed to 

support 1 large subpopulation (450 acres); 3 medium subpopulations (300 acres each); and 4 small 

subpopulations (150 acres each). 

There are only about 205 acres of protected riparian shrubland habitat within the central PCAs, or 

about 10 percent of the objective. No PCAs have greater than 100 protected acres of riparian 
Willamette Valley Conservation Study 

H-8 Appendix H. GAP Analysis 

Yellow breasted chat/USFWS 

shrubland. Only 4 PCAs have more than 10 protected acres: Corvallis Area Forests and Balds (north) 

[PCA 32] has 96 acres which includes ODFW’s E.E. Wilson Wildlife Management Area; Ankeny 

NWR-Salem Hills [PCA 42] has about 48 acres; Corvallis Area Forests and Balds (south) [PCA 22] 

has about 35 acres; and Minto Island [PCA 45] has a little over 10 acres. No other PCA has more 

than 10 acres of protected habitat. None of the PCAs meet any of the habitat objectives. 

Priority PCAs for riparian shrubland conservation include Ankeny NWR-Salem Hills [PCA 42]; 

Bowers Rock-Truax Island [PCA 18]; Corvallis Area Forests and Balds (north [PCA 32] and south 

[PCA 22]); Minto Island [PCA 45]; and Santiam Confluences [PCAs 29, 30, 33, and 34]. 

South 

In the southern section of the valley, the objective is for 1,500 acres of core riparian shrubland habitat 

to be managed for yellow-breasted chat and other riparian shrubland wildlife. Habitat should be 

distributed to support 6 subpopulations of yellow-breasted chat, consisting of 1 large subpopulation 

(450 acres), 2 medium subpopulations (300 acres each), and 3 small subpopulations (150 acres each). 

Approximately 510 acres of riparian shrubland are protected within the southern PCAs, primarily 

within 3 PCAs: Finley NWR/Muddy Creek [PCA 14] with 184 acres; West Eugene-Spencer 

Creek/Coyote Creek [PCA 6] with 214 acres; and McKenzie-Willamette Confluence/Harper's Bend 

Horseshoe Bar [PCA 8] with 56 acres. Two other PCAs each have between 10-50 acres of protected 

riparian shrubland habitat. 

Finley NWR/Muddy Creek [PCA 14] meets the objectives for 1 of the 3 small core patches. 

Protected riparian shrublands in the West Eugene-Spencer Creek/Coyote Creek [PCA 6] are too 

scattered to be considered a core habitat patch. With additional efforts, small, medium, or large core 

habitat patches could be protected. No other areas are close to meeting the objectives. 

Priority areas for additional riparian shrubland conservation include: Finley NWR/Muddy Creek 

[PCA 14]; West Eugene-Spencer Creek/Coyote Creek [PCA 6]; McKenzie-Willamette 

Confluence/Harper's Bend Horseshoe Bar [PCA 8]; Middle Fork-Coast Fork Confluence/Mount 

Pisgah [PCA 3]; Ingram Island [PCA 11]; and Long Tom-Willamette Confluence [PCA 13]. 

Discussion 

Overall, there are not enough lands being managed for the targeted species to meet all of the 

objectives for any targeted species/habitat combination. 

 

 
Willamette Valley Conservation Study 

Appendix H. GAP Analysis H-9 

The following series of tables provides a graphical representation of where in the valley objectives 

have been achieved, where they have been partially achieved, and where no protected areas are of 

sufficient size to meet any of the objectives. The number in the “Objective” column is the 

subpopulation/habitat patch objective. The number in the “Achieved” column is the number of 

subpopulations/habitat patches secured under some form of habitat protection. 

Table H1. The Status of Achieving Habitat Protection Objectives in the Willamette Valley 

Grassland 

Section Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North N/A N/A 1 1 2 0 

Center 1 1 2 0 4 0 

South 1 1 2 0 6 0 

Oak Savanna 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 1 0 3 0 6 0 

Center 2 0 3 0 6 1 

South 1 0 3 0 5 1 

Oak Woodland 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 5 1 10 1 20 1 

Center 5 0 10 0 20 1 

South 5 0 10 1 19 1 

Riparian Forest 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 3 1* 5 0 11 2 

Center 2 1 5 0 11 0 

South 2 1 5 1 11 3 

Riparian Shrubland 

Area Large Medium Small 

Objective Achieved Objective Achieved Objective Achieved 

North 1 1** 2 0 4 1** 
Willamette Valley Conservation Study 

H-10 Appendix H. GAP Analysis 

Center 1 0 3 0 4 0 

South 1 0 2 0 3 1 

* Sandy River Delta (not GAP 1 or 2) 

**= Objective met by lands not currently rated as GAP Status 1 or 2. See text for explanation.

 = Objectives achieved 

 = Objectives partially achieved 

 = No objectives achieved 
Willamette Valley Conservation Study 

Appendix I. Threats Analysis I-1 

Appendix I. Threats Analysis 

Introduction 

Estimating the level of threat that a priority area might be converted to some other land use rendering 

it unsuitable for conservation is an important step in systematic conservation planning (Margules and 

Pressey 2000). Understanding potential threats is a critical step in developing appropriate 

conservation strategies, and identifying the Priority Conservation Areas (PCAs) most threatened with 

conversion and thus in most need of urgent attention (Surasinghe et al. 2012; Groves 2003). 

Threats analyses require peering into the future which always adds an element of uncertainty. 

Unpredictable changes to land use laws further cloud the situation, as has been the recent history in 

Oregon and the Willamette Valley. Passage of Senate Bill 100 in 1973 marked a milestone for land 

use planning in Oregon. It required every city and county to prepare a comprehensive plan in 

accordance with a set of general statewide planning goals. The planning goals covered a wide range 

of topics including preservation of agricultural lands (Goal 3), forest lands (Goal 4), and open spaces, 

scenic and historic areas, and natural resources (Goal 5). Over the ensuing years, three ballot 

measures to overturn SB 100 were rejected by the voters. 

In 2004, Oregon voters passed Ballot Measure 37 which allowed property owners whose property 

value had been reduced by environmental or other land use regulations enacted after they became 

owners of the property to claim compensation from state or local governments. In lieu of 

compensation, the measure provided that the government responsible for the regulation may choose 

to “remove, modify or not apply” the regulation. Thousands of Measure 37 compensation claims 

were filed, but because municipalities could not afford the compensations costs, the land use laws 

were typically waived unleashing new developments in areas current laws would not allow. 

In 2007, Oregon voters passed Ballot Measure 49 which modified Measure 37 to give landowners 

with Measure 37 claims the right to build homes as compensation for land use restrictions imposed 

after they acquired their properties. It also allowed claimants to transfer homebuilding rights upon 

sale or transfer of the property. While Measure 49 significantly pared back Measure 37, one only has 

to drive the back roads of the Willamette Valley to readily see the steady fragmentation of farmlands 

and wildlife habitat resulting from Measures 37 and 49. The point here is that that the laws and rules 

passed by one generation may be repealed by the next adding uncertainty to any threats analysis. 

When factored in conjunction with a steady increase in land values this suggests some degree of 

urgency to develop additional conservation capacity within the Willamette Valley. 

A wide variety of agents can threaten the integrity of core priority areas, but due to the historic loss 

and conversion of native habitats and the anticipated surge in population growth (ODAS 2013), 

anthropogenic land use will likely present a greater challenge to restoring and maintaining 

biodiversity this century, than climate change (Wilson et al. 2014). Because of that, we focused on 

the potential for future development to occur within priority core areas as the main threat facing 

unprotected PCAs. An analysis of this type requires the development of alternative future scenarios 

that may play out over time in the planning area. We focused on two analyses conducted by others. 

The first is the projected future developed for the Willamette River Basin Planning Atlas (Hulse et al. 

2002), and the second is projected exurban housing impacts (Theobald 2005). 
Willamette Valley Conservation Study 

I-2 Appendix I. Threats Analysis 

Willamette River Basin Planning Atlas 

As described in the Willamette River Basin Planning Atlas: Trajectories of Environmental and 

Ecological Change (Hulse et al. 2002), the Willamette River basin was the subject of an extensive 

study of potential alternative futures that, over a 30-month period, involved a broad cross-section of 

stakeholders including lay and professional citizen groups, agriculture, industry, and scientists. This 

broad cross-section of stakeholders created, mapped, and evaluated a set of three land use scenarios 

for the year 2050: Plan Trend, Development, and Conservation (Hulse et al 2004). All three futures 

assume a doubling of the 1990 human population by 2050 (Baker et al. 2004), consistent with growth 

projections for the valley (ODAS 2013). 

The Plan Trend 2050 scenario represents the valley’s expected landscape in 2050 if current land use 

policies are implemented and recent trends continue. Development 2050 reflects a loosening of land 

use policies that allows market forces freer rein across all components of the valley’s landscape, but 

still within the range of what stakeholders considered plausible. Conservation 2050 places greater 

emphasis on ecosystem protection and restoration, reflecting a plausible balance among ecological, 

social, and economic considerations as defined by the stakeholders (Baker et al. 2004). 

These alternative future scenarios represent the most in-depth, stakeholder vetted scenarios for the 

valley in existence. The scenarios are spatially and temporally explicit, with projections provided by 

decade until the year 2050. The results are presented in the Willamette River Basin planning Atlas 

(Hulse et al. 2002), and further described in Ecological Applications, a peer-reviewed scientific 

journal (Baker et al. 2004). The scenarios and supporting metadata are available at 

http://www.fsl.orst.edu/pnwerc/wrb/access.html. Because this analysis is about potential 

development threats to identified core priority areas, we focused our analysis on the Development 

2050 scenario. 

Since 1973, Oregon has maintained a strong statewide land use planning program. The foundation of 

the program is a set of 19 Statewide Planning Goals that express the state's policies on land use and 

related topics, such as the protection of natural resources, scenic and historic areas, open spaces, 

farmland, and forests; and provide an orderly and efficient transition from rural to urban land uses. 

Under Oregon law, each of the state’s cities and metropolitan areas created an urban growth 

boundary (UGB) around their perimeters, which is a land use planning line to control urban 

expansion onto farm and forest lands beyond the UGB. Land inside the UGB is designated for urban 

uses. The location of a UGB is revised periodically, in order to maintain a 20-year supply of land to 

meet population and employment growth projections. 

Under Plan Trend 2050, new development occurs only within designated UGBs and existing rural 

residential zones. But because of the projected population growth, the amount of urbanized land, plus 

land influenced by rural development, increases, but by less than 25 percent. Rural residential zones 

are projected to be completely built-out by 2020. UGBs are expanded by 11 percent (51,000 acres). 

Under the Development 2050 scenario, new development occurs at lower densities over a larger rural 

area, leading to the fragmentation and conversion of agricultural fields. UGBs expand by 29 percent 

(129,000 acres) and the areas influenced by rural structures increases by 68 percent (121,500 acres). 

Projected Land Use Modifications 

We also looked at the projected percentage of change in each PCA that would be functionally 

modified by human land use (e.g., exurban housing growth, infrastructure) by 2050, using data from 
Willamette Valley Conservation Study 

Appendix I. Threats Analysis I-3 

Theobald (2005). Forecasted patterns of exurban growth were generated by the Spatially Explicit 

Regional Growth Model, which used historical and current housing density patterns to develop a 

simulation model that forecasts future housing density patterns and projections (Theobald 2005). 

Results 

To complete the threats analysis, we intersected land cover maps developed for the Development 

2050 scenario and changes in exurban growth, with the map of PCAs. We calculated the percentage 

of increase in developable land use types from 2010 to 2050 within each PCA for the Development 

2050 scenario, and from 2010 to 2020 for the exurban housing development scenario, and plotted the 

results on scatter charts. The charts were divided into quadrats (Threat Levels 1-4) based on the 

amount of targeted habitat types within the PCA and the increase in developable land use types: 

 Threat Level 1: PCAs with greater than (>) 2,000 acres of combined targeted habitat and >10 

percent of the land is located within future development land use zones. 

 Threat Level 2: PCAs with less than (<) 2,000 acres of combined targeted habitat but with 

>10 percent of the land located within future development land use zones. 

 Threat Level 3: PCAs with >2,000 acres of combined targeted habitat, but with <10 percent 

of the land located within future development land use zones. 

 Threat Level 4: PCAs with <2,000 acres of combined targeted habitat, and with <10 percent 

of the land located within future development land use zones. 

PCAs that have none of their lands impacted by projected development are not included in the 

results. 

Development 2050 Scenario 

The analysis of the Development 2050 scenario revealed that none of the PCAs fall within Threat 

Level 1. Only seven PCAs fall within Threat Level 2, and 14 PCAs fall within Threat Level 3. These 

PCAs are identified in Table I1. 

Not surprisingly, most of the PCAs under the greatest threat for future development occur close to 

major urban areas (Portland and Eugene). Two of these PCAs currently house national wildlife 

refuges and one supports a population of a listed plant species. 

Some of the PCAs with multiple wildlife values, such as West Eugene-Spencer Creek/Coyote Creek 

[PCA 6] and the Corvallis Area Forests and Balds (south) [PCA 21], which provide habitat for most 

of the targeted wildlife species as well as several listed species are in Threat Category 2. That these 

PCAs are among the most threatened only highlights the need for immediate actions to conserve 

these valuable places. 

Table I1. PCAs Predicted to be Impacted by Development (2050 Scenario) 

PCA 

ID PCA Name Habitat Acres 

% Land Cover 

Developed 

(2010-2050) 

PCAs in Threat Category 2 

72 Gales Creek 155 42.0% 

4 Lower McKenzie Oaks 1,391 28.2% 

66 Tualatin River NWR 1,357 21.6% 

71 Jackson Bottoms Area 918 16.4% 
Willamette Valley Conservation Study 

I-4 Appendix I. Threats Analysis 

PCA 

ID PCA Name Habitat Acres 

% Land Cover 

Developed 

(2010-2050) 

12 Sweet Home Lomatium Site 54 12.8% 

69 Wapato Lake NWR/Ribbon Ridge 1,952 11.3% 

5 Lower McKenzie River 1,635 10.3% 

PCAs in Threat Category 3 

6 West Eugene-Spencer Creek/ Coyote Creek 19,095 8.5% 

57 Mollala River and Grasslands 2,809 6.3% 

49 Eola Hills 3,948 5.6% 

22 Corvallis Area Forests and Balds (south) 11,063 4.9% 

42 Ankeny NWR-Salem Hills 12,477 4.2% 

7 Coburg Hills (south) 2,153 3.7% 

50 Grand Island (south) 3,316 2.7% 

8 McKenzie-Willamette Confluence/Harper's Bend 

Horseshoe Bar 2,176 1.8% 

3 Middle Fork-Coast Fork Confluence/Mount Pisgah 3,129 1.5% 

56 Yamhill Oaks 8,529 1.0% 

14 Finley NWR/Muddy Creek 6,942 0.2% 

46 Baskett Slough NWR (east) 3,356 0.2% 

32 Corvallis Area Forests and Balds (north) 3,270 0.2% 

9 Coburg Hills (north) 3,271 0.1% 

Projected Land Use Modifications 

The results of the projected percent change in human land use (e.g., exurban housing growth, 

infrastructure) by 2050, using data from Theobald scenario largely mimicked those from the 

Willamette River Basin Planning Atlas. The analysis revealed that none of the PCAs fell within 

threat category 1 and only a handful of PCAs fell within threat category2. These are all in 

Washington County, which is expected to grow rapidly over the coming decades. Wapato Lake 

NWR/Ribbon Ridge [PCA 69] falls within this category. 

All of the 14 PCAs with more than 2,000 acres of targeted habitat types fell into threat category 3. 

None of PCAs is expected to lose more than five percent of their area to exurban housing. Ankeny 

NWR-Salem Hills [PCA 42] at 4.9 percent loss had the highest predicted loss of these 14 PCAs 

(Table I2). 

Table I2. PCAs Predicted to be Impacted by Exurban Housing Development 

PCA 

ID PCA Name Habitat Acreage 

Change in 

Human Land Use 

(2010-2050) 

PCAs in Threat Category 2 

74 Banks Swamp 300 20.7% 

72 Gales Creek 156 19.1% 

71 Jackson Bottoms Area 918 16.7% 

67 Tualatin River 257 15.2% 

76 Dairy Creek - Red Slide Hill 173 10.6% 

69 Wapato Lake NWR/ Ribbon Ridge 1,953 10.0% 
Willamette Valley Conservation Study 

Appendix I. Threats Analysis I-5 

PCA 

ID PCA Name Habitat Acreage 

Change in 

Human Land Use 

(2010-2050) 

PCAs in Threat Category 3 

42 Ankeny NWR-Salem Hills 12,477 4.9% 

50 Grand Island (south) 3,316 3.1% 

56 Yamhill Oaks 8,529 2.5% 

57 Mollala River and Grasslands 2,809 2.0% 

49 Eola Hills 3,948 1.0% 

8 McKenzie-Willamette Confluence/Harper's Bend 

Horseshoe Bar 

2,176 1.0% 

6 West Eugene-Spencer Creek/Coyote Creek 19,095 0.9% 

22 Corvallis Area Forests and Balds (south) 11,063 0.9% 

3 Middle Fork-Coast Fork Confluence/Mount Pisgah 3,129 0.6% 

7 Coburg Hills (south) 2,153 0.4% 

46 Baskett Slough NWR (east) 3,356 0.4% 

32 Corvallis Area Forests and Balds (north) 3,270 0.2% 

14 Finley NWR/Muddy Creek 6,942 0.1% 

9 Coburg Hills (north) 3,271 0.0% 

 
Willamette Valley Conservation Study 

I-6 Appendix I. Threats Analysis 

This document continues on the next page. 
Willamette Valley Conservation Study

Appendix J. Literature Cited J-1

Altman, B. 1997. Distribution, abundance, and habitat associations of declining and state sensitive 

bird species breeding in Willamette Valley grasslands. Prepared for: Oregon Department of Fish 

and Wildlife. 

Altman, B. 1999. Status and conservation of state sensitive grassland bird species in the Willamette 

Valley. A report to the Oregon Department of Fish and Wildlife. 

Altman, B. 2001. Conservation Strategy for Landbirds in Lowlands and Valleys of Western Oregon 

and Washington. Prepared for: Oregon-Washington Partners in Flight. 

Altman, B., M. Hayes, S. Janes, and R. Forbes. 2001. Wildlife of Westside Grassland and Chaparral 

Habitats. In. Johnson, D.H., and T.A. O’Neil. 2001. Wildlife-Habitat Relationships in Oregon and 

Washington. Oregon State University Press. Corvallis, OR. 

Altman, B. 2010. Habitat and Population Objectives for Landbirds in Priority Upland and Riparian 

Habitats in the Puget Lowlands Ecoregion. Pacific Coast Joint Venture. 

Altman, B. 2011. Historical and current distribution and populations of bird species in prairie-oak 

habitats in the Pacific Northwest. Northwest Science 85:194-222. 

Altman, B., M. Blakeley-Smith, K. Halsted, and A. Kreager. 2011. Western meadowlarks and wet 

prairie habitat in the Willamette Valley: population enhancement through private land habitat 

restoration. 

Altman, B. and J.L. Stephens. 2012. Land managers guide to bird habitat and populations in oak 

ecosystems of the Pacific Northwest. American Bird Conservancy and Klamath Bird Observatory. 

Akcakaya, R.H. 2000. Viability analysis with habitat-based metapopulation models. Population 

Ecology 42:45-53. 

Akcakaya, R.H., G. Mills, and C.P. Doncaster. 2007. The role of metapopulations in conservation in:

Key topics in conservation biology. Macdonald D.W. and K. Service eds. 2007. Blackwell 

Publishing Ltd. Malden, MA. 

American Bird Conservancy (ABC). 2006. Top 20 most threatened bird habitats in the United States. 

Bird Conservation, Summer 2006. 

Andelman, S.J., and M.R. Willig. 2002. Alternative configurations of conservation reserves for 

Paraguayan bats: considerations of spatial scale. Conservation Biology 16:1352-1363. 

Araújo, M.B., and A.T. Peterson. 2012. Uses and misuses of bioclimatic envelope modeling. Ecology 

93:1527-1539. 

Ardron, J.A., H.P. Possingham, and C.J. Klein, (editors). 2010. Marxan Good Practices Handbook, 

Version 2. Pacific Marine Analysis and Research Association, Victoria, BC, Canada. 

Arid Lands Initiative. 2014. Spatial Conservation Priorities in the Columbia Plateau Ecoregion: 

Methods and data used to identify collaborative conservation priority areas for the Arid Lands 

Initiative. https://www.sciencebase.gov/catalog/folder/52050595e4b0403aa6262c64. 

Bachelet, D., B.R. Johnson, S.D. Bridgham, P.V. Dunn, H.E. Anderson, and B.M. Rogers. 2011. 

Climate change impacts on western Pacific Northwest prairies and savannas. Northwest Science 

85:411-429. 

Appendix J. Literature Cited 
Willamette Valley Conservation Study 

J-2 Appendix J. Literature Cited 

Baker. J.P., D.W. Hulse, S.V. Gregory, D. White, J. Van Sickle, P.A. Berger, D. Dole, and N.H. 

Schumaker. 2004. Alternative Futures for the Willamette River Basin, Oregon. Ecological 

Applications 14:313-324. 

Ball, I.R. and H.P. Possingham. 2000. MARXAN (V1.8.2): Marine Reserve Design Using Spatially 

Explicit Annealing, a Manual. 

Ball, I.R., H.P. Possingham, and M. Watts. 2009. Marxan and relatives: Software for spatial 

conservation prioritization. Chapter 14:185-195 in Spatial Conservation Prioritization: 

Quantitative methods and computational tools. Moilanen, A., K.A. Wilson, and H.P. Possingham 

(editors.). Oxford University Press, Oxford, UK. 

Beck, M.W., and M. Odaya. 2001. Ecoregional planning in marine environments: Identifying priority 

sites for conservation in the northern Gulf of Mexico. Aquatic Conservation 11:235-242. 

Bachelet, D., B.R. Johnson, S.D. Bridgham, P.V. Dunn, H.E. Anderson, and B.M. Rogers. 2011. 

Climate change impacts on western Pacific Northwest prairies and savannas. Northwest Science 

85(2):411-429. 

Blancher, P.J., K.V. Rosenberg, A.O. Panjabi, B. Altman, J. Bart, C.J. Beardmore, G.S. Butcher, D. 

Demarest, R. Dettmers, E.H. Dunn, W. Easton, W.C. Hunter, E.E. Iñigo-Elias, D.N. Pashley, C.J. 

Ralph, T.D. Rich, C.M. Rustay, J.M. Ruth, and T.C. Will. 2007. Guide to the Partners in Flight 

Population Estimates Database. Version: North American Landbird Conservation Plan 2004. PIF 

Technical Series No. 5. 

Blancher, P.J., K.V. Rosenberg, A.O. Panjabi, B. Altman, A.R. Couturier, W.E. Thogmartin, and the 

Partners in Flight Science Committee. 2013. Handbook to the Partners in Flight Population 

Estimates Database, Version 2.0. PIF Technical Series No. 6. 

Brennan, L.A., and W.P. Kuvlesky Jr. 2005. North American Grassland Birds: An Unfolding 

Conservation Crisis? Journal of Wildlife Management 69:1-13. 

Bull, James C., Nicola J. Pickup, Brian Pickett, Michael P. Hassell, and Michael B. Bonsall. 2007. 

Metapopulation extinction risk is increased by environmental stochasticity and assemblage 

complexity. Proc. R. Soc. B. 274:87-96. Buttrick, S., B. Unnasch, M. Schindel, K. Popper, S. 

Scott, A. Jones, B. McRae, and M. Finnerty. 2014. Resilient Sites for Terrestrial Conservation in 

the Northwest. The Nature Conservancy. 

https://www.conservationgateway.org/ConservationByGeography/NorthAmerica/UnitedStates/ore

gon/science/Pages/Resilient-Landscapes.aspx. 

Brennan, L.A., and W.P. Kuvlesky. 2005. North American Grassland Birds: an unfolding crisis. 

Journal of Wildlife Management 69:1-13. 

Brown, S., C. Hickey, B. Harrington, and R. Gill, eds. 2001. The U.S. Shorebird Conservation Plan, 

2nd ed. Manomet Center for Conservation Sciences, Manomet, MA. 

Carroll, C., R.F. Noss, P.C. Paquet, and N.H. Schumaker. 2003. Use of population viability analysis 

and reserve selection algorithms in regional conservation plans. Ecological Applications 

13:S1773‐S1789 

Carver, E., and J. Caudill, Ph.D. 2013. Banking on Nature: The Economic Benefits to Local 

Communities of National Wildlife Refuge Visitation. Division of Economics. U.S. Fish and 

Wildlife Service, Washington DC. 

Center for American Progress. 2016. The Disappearing West. Available at 

www.disappearingwest.org. Accessed December 1, 2016. 
Willamette Valley Conservation Study

Appendix J. Literature Cited J-3

Chappell, C.B., R.C. Crawford, C. Barrett, J. Kagen, D.H. Johnson, M. O’Mealy, G.A. Green, H.L. 

Ferguson, W.D. Edge, E.L. Greda, and T.A. O’Neil. 2001. Wildlife Habitats: Descriptions, Status, 

Trends, and System Dynamics. In. Johnson, D.H., and T.A. O’Neil. 2001. Wildlife-Habitat 

Relationships in Oregon and Washington. Oregon State University Press. Corvallis, OR. 

Chen, I., J.K. Hill, R. Ohlemϋller, D.B. Roy, and C.D. Thomas. 2011. Rapid range shifts of species 

associated with high levels of global warming. Science. 333:1024-1026. 

Christy, J.A., and E.R. Alverson. 2011. Historical vegetation of the Willamette Valley, Oregon, circa 

1850. Northwest Science 85:93-107. 

Chang, H., and I.W. Jung. 2010. Spatial and temporal changes in runoff caused by climate change in 

a complex large river basin in Oregon. Journal of Hydrology, 388(3):186-207. 

Climate Leadership Initiative. 2008. Preparing the Pacific Northwest for Climate Change: A 

Framework for Integrative Preparation Planning for Natural, Human, Built and Economic 

Systems. Climate Leadership Initiative, Institute for a Sustainable Environment, University of 

Oregon. Eugene, OR. 

City of Portland and Multnomah County. 2015. Climate Action Plan: local strategies to address 

climate change. Portland, OR. 

Columbia River Inter-Tribal Fish Commission (CRITFC). 2011. Tribal Pacific lamprey restoration 

plan for the Columbia River Basin. Columbia River Inter-Tribal Fish Commission, Portland, OR. 

Connolly, T.J. 2000. Anthropological and Archaeological Perspectives on Native Fire Management 

of the Willamette Valley. Paper presented at the 81st Annual Meeting of the American 

Association for the Advancement of Science, Pacific Division (Symposium: Fire History in the 

Pacific Northwest: Human and Climatic Influences), June 11-14, 2000, Ashland, OR. 

http://www.orww.org/Kalapuya-Amin_2006/Program/ConnollyT/Indian_Burning_20000611.pdf 

Conresy, Reesa Y., Susan K. Skagen, Amy A. Yackel Adams, and Arvind O. Panjabi. 2016. 

Extremes of heat, drought, and precipitation depress reproductive performance in shortgrass 

prairie passerines. Ibis. 185:614-629. 

Csuti, B., T.A. O’Neil, M.M. Shaughnessy, E.P. Gaines, and J.C. Hak. 2001. Atlas of Oregon 

Wildlife: Distribution, Habitat, and Natural History, 2nd edition. Oregon State University Press. 

Corvallis, OR. 

Dean Runyan Associates. 2009. Fishing, Hunting, Wildlife Viewing, and Shellfishing in Oregon: 

2008 State and County Expenditure Estimates. Prepared for the Oregon Department of Fish and 

Wildlife and Travel Oregon. 72p. 

Defenders of Wildlife. 1998. Oregon’s living landscape: strategies and opportunities to conserve 

biodiversity. University of Arizona Press. Tucson, AZ. 

Dulière, V., Y. Zhang, and E.P. Salathé Jr. 2011. Extreme Precipitation and Temperature over the 

U.S. Pacific Northwest: A Comparison between Observations, Reanalysis Data, and Regional 

Models. Journal of Climate, 24(7):1950-1964. 

Drut, M.S., and J.B. Buchanan. 2000. Northern Pacific Coast Regional Shorebird Plan. U.S. Fish and 

Wildlife Service. Portland, OR. 

Flather, C.H., G.D. Hayward, S.R. Beissinger, and P.A. Stephens. 2011. Minimum viable 

populations: Is there a ‘magic number’ for conservation practitioners? Trends in Ecology and 

Evolution 26:307–316. 
Willamette Valley Conservation Study 

J-4 Appendix J. Literature Cited 

Floberg, J., M. Goering, G. Wilhere, C. MacDonald, C. Chappell, C. Rumsey, Z. Ferdana, A. Holt, P. 

Skidmore, T. Horsman, E. Alverson, C. Tanner, M. Bryer, P. Iachetti, A. Harcombe, B. 

McDonald, T. Cook, M. Summers, D. Rolph. 2004. Willamette Valley-Puget Trough-Georgia 

Basin Ecoregional Assessment, Volume One: Report. Prepared by The Nature Conservancy with 

support from the Nature Conservancy of Canada, Washington Department of Fish and Wildlife, 

Washington Department of Natural Resources (Natural Heritage and Nearshore Habitat 

programs), Oregon State Natural Heritage Information Center, and the British Columbia 

Conservation Data Centre. 

Gabrielson, I.N., and S.G. Jewett. 1940. Birds of Oregon. Oregon State College, Corvallis, OR. 

(reprinted in 1970 as Birds of the Pacific Northwest. Dover Publishing. New York, NY.) 

Game, E.T., and H.S. Grantham. 2008. Marxan User Manual for Marxan version 1.8.10. University 

of Queensland, St. Lucia, Queensland, Australia, and Pacific Marine Analysis and Research 

Association, Vancouver, BC, Canada. 

Glick, P., B.A. Stein, and N.A. Edelson, editors. 2011. Scanning the Conservation Horizon: A Guide 

to Climate Change Vulnerability Assessment. National Wildlife Federation, Washington, DC. 

http://www.habitat.noaa.gov/pdf/scanning_the_conservation_horizon.pdf

Gregory, R.D., P. Vořišek, D.G. Noble, A. Van Strien, A. Klvaňova ́, M. Eaton, A.W.G. Meyling, A. 

Joys, R.P.B. Foppen, and I.J. Burfield. 2008. The generation and use of birds population 

indicators in Europe. Bird Conservation International 18:S223-S244. 

Groom, M.J., G.K. Meefe, and C.R. Carroll. 2006. Principles of Conservation Biology, Third 

Edition. Sinauer Associates, Inc. Sunderland, MA. 

Groves, C.R. 2003. Drafting a conservation blueprint: a practitioner’s guide to planning for 

biodiversity. Island Press. Washington DC. 

Groves, C., L. Valutis, D. Vosick, B. Neely, K. Wheaton, J. Touval, and B. Runnels. 2000a. 

Designing a Geography of Hope: A Practitioner’s Handbook for Ecoregional Conservation 

Planning. The Nature Conservancy. Langley, VA. 

Groves, C.R., D.B. Jensen, L.L. Valutis, K.H. Redford, M.L. Shaffer, J.M. Scott, J.V. Baumgartner, 

J.V. Higgins, M.W. Beck, and M.G. Anderson. 2002. Planning for Biodiversity Conservation: 

Putting Conservation Science into Practice. BioScience. 52:499-512. 

Grubb Jr., T.C., and V.V. Pravosudov. 2008. White-breasted Nuthatch (Sitta carolinensis), The Birds 

of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the 

Birds of North America at http://bna.birds.cor-nell. edu/bna/species/054

Guinan, J.A., P.A. Gowaty, and E.K. Eltzroth. 2008. Western Bluebird (Sialia mexicana), The Birds 

of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the 

Birds of North America Online: http://bna.birds.cornell.edu/bna/species/510 

Hanski, I., and M. Gilpen. 1991. Metapopulation dynamics: brief history and conceptual domain. 

Biological Journal of the Linnean Society 42:3-16 

Hanski, I.A. 1998. Metapopulation dynamics. Nature 396:41-49. 

Hanski, I., and O. Ovaskainen. 2002. Extinction debt at extinction threshold. Conservation Biology 

16:666-673. 
Willamette Valley Conservation Study

Appendix J. Literature Cited J-5

Hagar, J.C. 2003. White‐breasted nuthatch (Sitta carolinensis). Pp 449‐451. In Marshall, D.B., M.G. 

Hunter, and A.L. Contreras. Birds of Oregon: A General Reference. Oregon State University 

Press, Corvallis, OR. 

Hamman, S.T., P.W. Dunwiddie, J.L. Nuckols, and M. McKinley. 2011. Fire as a restoration tool in 

the Pacific Northwest prairies and oak woodlands: challenges, Successes, and future directions. 

Northwest Science 85:317-328. 

Hamann, A., D.R. Roberts, Q.E. Barber, C. Carroll, and S.E. Nielsen. 2014. Velocity of climate 

change algorithms for guiding conservation and management. Global Change Biology. DOI:10. 

Heller, Nicole E., and Erika S. Zavaleta. 2009. Biodiversity Management in the Face of Climate 

Change: A Review of 22 Years of Recommendations. Biological Conservation, 142:14-32. 

Hellerstein, D., N. Higgins, and M. Roberts. 2015. Options for improving conservation programs: 

Insights from auction theory and economic experiments, ERR-181. U.S. Department of 

Agriculture, Economic Research Service, January 2015. 

Hulse D., S. Gregory, and J. Baker editors. 2002. Willamette River Basin Planning Atlas: 

Trajectories of Environmental and Ecological Change, 2nd edition. Oregon State University Press, 

Corvallis, OR. 

Hulse, D.W., A. Branscomb, C. Enright, S.V. Gregory, and R. Whitman. 2007. Linking cold-water 

refuges into a biologically effective network in the southern Willamette River floodplain: 

outlining key locations and knowledge gaps. 

Hulse, D.W., A. Branscomb, C. Brehm, C. Enright, S.V. Gregory, and S. Wright. 2013. Assessment 

of potential for improving ESA-listed fish habitat associated with operations and maintenance of 

the U.S. Army Corps of Engineers Willamette Project: an approach to prioritizing revetments for 

removal or modification to restore natural river function. U.S. Army Corps of Engineers, Portland, 

OR. 

Institute for Applied Ecology (IAE). 2010. Benton County, Oregon: prairie conservation strategy. 

December 2010. 

IPCC (Intergovernmental Panel on Climate Change). 2014. Climate Change 2014: Impacts, 

Adaptation, and Vulnerability. Part A: Global and Sectoral Aspects. Contribution of Working 

Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change 

[Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea, T.E. Bilir, M. Chatterjee, 

K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken, P.R. 

Mastrandrea, and L.L.White (eds.)]. Cambridge University Press, Cambridge, UK, and New 

York, NY. 

Johannessen, C.L., W.A. Davenport, A. Millet, and S. McWilliams. 1971. The Vegetation of the 

Willamette Valley. Annals of the Association of American Geographers 61:286-302. 

Johnson, D.H., and M. Winter. 1999. Reserve design for grasslands: considerations for bird 

populations. Pages 391-396 in D. Harmon, (editor). On the Frontiers of Conservation: 

Proceedings of the Tenth Conference on Research and Resource Management in Parks and on 

Public Lands. The George Wright Soc. Biennial Conf., Asheville, NC. Jamestown, ND: Northern 

Prairie Wildlife Research Center Online. 

http://www.npwrc.usgs.gov/resource/birds/desgrs/index.htm (Version 16MAY2000). 

Johnson, D.H., and L.D. Igl. 2001. Area Requirements of Grassland Birds: A Regional Perspective. 

The Auk. 118:24-34. 
Willamette Valley Conservation Study 

J-6 Appendix J. Literature Cited 

Jones, S.L., and J.E. Cornely. 2002. Vesper Sparrow (Pooecetes gramineus), The Birds of North 

America Online (A. Poole, Editor). Ithaca: Cornell Lab of Ornithology. 

http://bna.birds.cornell.edu/bna/species/624

Jung, I.W., and H. Chang. 2011. Assessment of future runoff trends under multiple climate change 

scenarios in the Willamette River Basin, OR. Hydrological Processes 25:258-277. 

Kauffman, J.B., M. Mahrt, L.A. Mahrt, and W.D. Edge. 2001. Wildlife of Riparian Habitats. In. 

Johnson, D.H., and T.A. O’Neil. 2001. Wildlife-Habitat Relationships in Oregon and Washington. 

Oregon State University Press. Corvallis, OR. 

Keyser, A.J., M.T. Keyser, and D.E.L. Promislow. 2004. Life-history variation and demography in 

western bluebirds (Salix mexicana) in Oregon. The Auk 121:118-133. 

Knutti, R., and J. Sedláček. 2013. Robustness and uncertainties in the new CMIP5 climate model 

projections. Nature Climate Change, 3(4):369-373. 

Lande, Russell. 1993. Risks of population extinction from demographic and environmental 

stochasticity and random catastrophes. The American Naturalist. 142:911-927. 

Langdon, J.G.R. 2013. Forecasting the Impact of Climate Change on Terrestrial Biodiversity and 

Protected Areas in the Pacific Northwest. Master's Thesis, University of Washington, 2013. 

http://hdl.handle.net/1773/23708. 

Larson, F.W., J. Blandt, A. Balmford, and C. Rahbek. 2012. Birds as biodiversity surrogates: will 

supplementing birds with other taxa improve effectiveness? Journal of Applied Ecology. 49:349-

356. 

Leslie, H., M. Ruckelshaus, I.R. Ball, S. Andelman, and H.P. Possingham. 2003. Using sitting 

algorithms in the design of marine reserves network. Ecological Applications, 13:185–198. 

Loarie, S.R., P.B. Duffy, H. Hamilton, G.P. Asner, C.B. Field, and D.D. Ackerly. 2009. The velocity 

of climate change. Nature 462:7276 

Lowther, P.E., C. Celada, N.K. Klein, C.C. Rimmer, and D.A. Spector. 1999. Yellow Warbler 

(Setophaga petechia), The Birds of North America Online (A. Poole, Editor). Ithaca: Cornell Lab 

of Ornithology. http://bna.birds.cornell.edu/bna/species/454

Luzier, C.W., H.A. Schaller, J.K. Bromstrom, C. Cook-Tabor, D.H. Goodman, R.D. Nelle, K. 

Ostrand, and B. Streif. 2011. Pacific Lamprey (Entosphenus tridentatus) Assessment and 

Template for Conservation Measures. U.S. Fish and Wildlife Service, Portland, OR. 

Margules, C.R. and R.L. Pressey. 2000. Systematic Conservation Planning. Nature 405:243‐253. 

Marshall, D.B., M.G. Hunter, and A.L. Contreras, eds. 2003. Birds of Oregon: A General Reference. 

Oregon State University Press. Corvallis, OR. 

Metro. 2012. Smith and Bybee Wetlands Natural Area: Comprehensive Natural Resource Plan. 

David Evans and Associates, Inc. Portland, OR. 

Michalak, J.L., J.C. Withey, and J.J. Lawler. 2013. Willamette Valley Climate Change Adaptation 

Workshop. Report prepared for the North Pacific Landscape Conservation Cooperative. School of 

Environmental and Forest Sciences, University of Washington, Seattle, WA. 

https://www.sciencebase.gov/catalog/file/get/527c38b0e4b0050d7e26b7e9?f=__disk__f7%2F0f%

2Fb5%2Ff70fb5e26ed740213bbfcecb32ab23f7cfa41634>. 
Willamette Valley Conservation Study

Appendix J. Literature Cited J-7

Michalak, J.L., J.C. Withey, and J.L. Lawler. 2013. Willamette Valley Climate Change Adaptation 

Workshop. Report prepared for the North Pacific Landscape Conservation Cooperative. School of 

Environmental and Forest Sciences. University of Washington, Seattle, WA. 

Mini, A.E. 2012. The Role of Body Size in the Foraging Strategies and Management of Avian 

Herbivores: A Comparison of Dusky Canada Geese (Branta canadensis occidentalis) and 

Cackling Geese (B. hutchinsii minima) Wintering in the Willamette Valley of Oregon. 

Dissertation for the degree of Doctor of Philosophy in Wildlife Science. Oregon State University. 

Corvallis, OR. 

Morlan, J.C., E.F. Blok, J. Miner, and W.N. Kirchner. 2010. Wetland and Land Use Change in the 

Willamette Valley, Oregon: 1994 to 2005. U.S. Fish and Wildlife Service, Portland, OR, and 

Oregon Department of State Lands, Salem, OR. 

National Ecological Assessment Team (NEAT). 2006. Strategic Habitat Conservation: A report from 

the National Ecological Assessment Team. June 29, 2006. 

Nakicenovic, N. et al. 2010. Special report on emissions scenarios, working group III, 

Intergovernmental Panel on Climate Change (IPCC). Cambridge University Press, Cambridge, 

UK. ISBN 0 521.80493. 

Natural Resource Conservation Service (NRCS). 1975. Soil Survey of Benton County, OR. 

Natural Resource Conservation Service (NRCS). 1982. Soil Survey of Washington County, OR. 

NatureServe. 2011. International Ecological Classification Standard: Terrestrial Ecological 

Classifications. NatureServe Central Databases. Arlington, VA. Data current as of July 31, 2011. 

North American Waterfowl Management Plan, Plan Committee (NAWMPPC). 2004. North 

American Waterfowl Management Plan 2004. Implementation Framework: Strengthening the 

Biological Foundation. Canadian Wildlife Service, U.S. Fish and Wildlife Service, Secretaria de 

Medio Ambiente y Recursos Naturales. 

North American Waterfowl Management Plan, Plan Committee (NAWMPPC). 2012. North 

American Waterfowl Management Plan 2012: People Conserving Waterfowl and Wetlands. 

Canadian Wildlife Service, U.S. Fish and Wildlife Service, Secretaria de Medio Ambiente y 

Recursos Naturales. 

Northwest Power and Conservation Council (NPCC). 2004. Draft Willamette Subbasin Plan. 

Prepared by the Willamette Restoration Initiative. 

Noss, R.F., E.T. LaRoe III, and J.M. Scott. 1995. Endangered Ecosystems of the United States: a 

preliminary assessment of loss and degradation. U.S. Department of the Interior. Biological 

Report 28. Feb. 1995. 

Noss, R.F., C. Carroll, K. Vance‐Borland, and G. Wuerthner. 2002. A multicriteria assessment of the 

irreplaceability and vulnerability of sites in the Greater Yellowstone Ecosystem. Conservation 

Biology 16:895‐908. 

O’Connor, R.J., M.T. Jones, R.B. Boone, and T.B. Lauber. 1999. Linking Continental Climate, Land 

Use, and Land Patterns with Grassland Bird Distribution across the Conterminous United States. 

Studies in Avian Biology 19:45-59. 

O’Neil, T.A., and D.H. Johnson. 2001. Oregon and Washington Wildlife Species and Their Habitats. 

In. D.H. Johnson, and T.A. O’Neil. 2001. Wildlife-Habitat Relationships in Oregon and 

Washington. Oregon State University Press. Corvallis, OR. 
Willamette Valley Conservation Study 

J-8 Appendix J. Literature Cited 

Omernik, J.M. 1987 Ecoregions of the conterminous United States: Annals of the Association of 

American Geographers 77:118-125. 

Oregon Climate Change Research Institute (OCCRI). 2010. Oregon Climate Assessment Report, 

Dello, K.D, and P.W. Mote (eds). College of Oceanic and Atmospheric Sciences, Oregon State 

University, Corvallis, OR. 

Oregon Biodiversity Information Center (OBIC). 2010. Rare, Threatened and Endangered Species of 

Oregon. Institute for Natural Resources, Portland State University, Portland, OR. 

Oregon Department of Administrative Services (ODAS). 2013. Forecasts of Oregon's County 

Populations and Components of Change, 2010-2050. March 28, 2013. 

Oregon Department of Environmental Quality (ODEQ). 2014. 2013 Oregon Air Quality Data 

Summaries. July 2014. 

Oregon Department of Fish and Wildlife (ODFW). Undated. The Willamette Valley Landowner’s 

Guide to Creating Habitat for Grassland Birds. 

Oregon Department of Fish and Wildlife (ODFW). Undated. Landowner’s Guide to Creating 

Grassland Habitat for Western Meadowlark and Oregon’s Other Grassland Birds. 

Oregon Department of Fish and Wildlife (ODFW). 2006. The Oregon Conservation Strategy. 

ODFW, Salem, OR. 

Oregon Department of Fish and Wildlife (ODFW). 2008. ODFW Sensitive Species List. ODFW, 

Salem, OR. 

Oregon Department of Fish and Wildlife (ODFW). 2010. Declining and state sensitive bird species 

breeding in the Willamette Valley Grasslands: 2008/09 status update. ODFW, Salem, OR. 

Oregon Department of Fish and Wildlife (ODFW). 2016. Oregon Conservation Strategy. Oregon 

ODFW, Salem, Oregon 

Oregon Department of Fish and Wildlife (ODFW) and National Marine Fisheries Service (NMFS). 

2011. Upper Willamette River Conservation and Recovery Plan for Chinook salmon and 

steelhead. ODFW, Salem, OR. 

Oregon Department of State Lands (ODSL). 1995. Oregon’s Wetland Conservation Strategy: Issue 

Analysis, Public Discussion and Recommendations. 

Oregon Department of Transportation (ODOT). 2012. ODOT’s Climate Change Adaptation Strategy 

Report. Salem, OR. 

Oregon Parks and Recreation Department (OPRD). 2008. Outdoor Recreation in Oregon: The 

changing face of the future. The 2008-2012 Oregon Statewide Comprehensive Outdoor 

Recreation Plan. February 2008. 

Oregon Progress Board (OPB). 2000. Oregon State of the Environment Report 2000: Statewide 

Summary. 

Oregon Watershed Enhancement Board (OWEB). 2014. Anchor Habitat Maps. 

http://www.oregon.gov/OWEB/Pages/SIPMaps.aspx. Accessed December 24, 2014. 

Pacific Flyway Council. 1998. Pacific Flyway management plan for Northwest Oregon-Southwest 

Washington Canada goose agricultural depredation control (unpublished report). Canada goose 

agricultural depredation working group, Pacific Flyway Study Comm. [c/o USFWS], Portland, 

OR. 
Willamette Valley Conservation Study

Appendix J. Literature Cited J-9

Pacific Flyway Council. 1999. Pacific Flyway management plan for the cackling Canada goose 

(unpublished report). Cackling Canada Goose Subcomm., Pacific Flyway Study Comm. [c/o 

USFWS],Portland, OR. 

Pacific Flyway Council. 2008. Pacific Flyway management plan for the dusky Canada goose 

(unpublished report). Dusky Canada Goose Subcomm., Pacific Flyway Study Comm. [c/o 

USFWS], Portland, OR. 

Pashley, D.N., C.J. Beardmore, J.A. Fitzgerald, R.P. Ford, W.C. Hunter, M.S. Morrison, K.V. 

Rosenberg. 2000. Partners in Flight: Conservation of the Land Birds of the United States. 

American Bird Conservancy. The Plains, VA. 

Paulson, D. 1993. Shorebirds of the Pacific Northwest. University of Washington Press, Seattle, WA. 

Pearson, S.F., and B. Altman. 2005. Range-wide Streaked Horned Lark (Eremophila alpestris 

strigata) Assessment and Preliminary Conservation Strategy. Washington Department of Fish and 

Wildlife, Olympia, WA. 

Reed, D.H., J.J. O’Grady, B.W. Brook, J.D. Ballou, and R. Frankham. 2003. Estimates of minimum 

viable population sizes for vertebrates and factors influencing those estimates. Biological 

Conservation. 113:23-34. 

Responsive Management. 2016. Oregon Residents’ Opinions On and Values Related To the Oregon 

Department of Fish and Wildlife. Conducted for the Oregon Legislative Task Force on Funding 

for Fish, Wildlife, and Related Outdoor Recreation and Education. Responsive Management, 

Harrisonburg, VA. 188pp.Rogers, B.M., J.T. Randerson,. and G.B. Bonan. 2013. High-latitude 

cooling associated with landscape changes from North American boreal forest fires. 

Biogeosciences, 10:699-718. 

Rosenberg, K. V., J. A. Kennedy, R. Dettmers, R. P. Ford, D. Reynolds, J.D. Alexander, C. J. 

Beardmore, P. J. Blancher, R. E. Bogart, G. S. Butcher, A. F. Camfield, A. Couturier, D. W. 

Demarest, W. E. Easton, J.J. Giocomo, R.H. Keller, A. E. Mini, A. O. Panjabi, D. N. Pashley, T. 

D. Rich, J. M. Ruth, H. Stabins, J. Stanton, T. Will. 2016. Partners in Flight Landbird 

Conservation Plan: 2016 Revision for Canada and Continental United States. Partners in Flight 

Science Committee. 119 pp. 

Rich, T.D., C.J. Beardmore, H. Berlanga, P.J. Blancher, M.S.W. Bradstreet, G.S. Butcher, D.W. 

Demarest, E.H. Dunn, W.C. Hunter, E.E. Iñigo-Elias, J.A. Kennedy, A.M. Martell, A.O. Panjabi, 

D.N. Pashley, K.V. Rosenberg, C.M. Rustay, J.S. Wendt, T.C. Will. 2004. Partners in Flight 

North American Landbird Conservation Plan. Cornell Lab of Ornithology. Ithaca, NY. 

River Design Group. 2012a. Willamette River Floodplain Inundation Mapping: Eugene to Oregon 

City. River Design Group, Corvallis, OR. 

River Design Group. 2012b. Middle Fork and Coast Fork Willamette River Floodplain Inundation 

Mapping. River Design Group, Corvallis, OR. 

River Design Group. 2013. McKenzie River Floodplain Inundation Mapping. River Design Group, 

Corvallis, OR. 

Rocchio, J., and R. Crawford. 2009. Field Guide to Washington’s Ecological Systems. Washington 

Natural Heritage Program. Washington Department of Natural Resources. Olympia, WA. 

Roth, E., B. Taylor, and E. Scheuering. 2004. Pacific Coast Joint Venture Implementation Plans: 

Willamette Valley (draft) Oregon Habitat Joint Venture. West Linn, OR. 
Willamette Valley Conservation Study 

J-10 Appendix J. Literature Cited 

Sauer, J.R., J.E. Hines, and J. Fallon. 2008. The North American Breeding Bird Survey, Results and 

Analysis 1966-2007. Version 5.15.2008. (Archived) USGS Patuxent Wildlife Research Center, 

Laurel, MD. 

Selman, M., S. Greenhalgh, M. Taylor, and J. Guiling. 2008. Paying for Environmental Performance: 

potential cost savings using a reverse auction in program sign-up. WRI Policy Note 

Environmental Markets No 5. World Resources institute. Washington DC. 

Shafer, S.l., P.J. Bartlein, and R.S. Thompson. 2001. Potential changes in the distributions of western 

North America tree and shrub taxa under future climate scenarios. Ecosystems 4:200-215. 

Shaffer, M.L. 1981. Minimum population sizes for species conservation. BioScience 31:131-134. 

Shriver, W., G. Vickery, and P.D. Vickery. 1999. Aerial Assessment of Potential Florida 

Grasshopper Sparrow Habitat: Conservation in a Fragmented Landscape. Florida Field Naturalist 

27:1-9. 

Sitch, S., B. Smith, I.C. Prentice, A. Arneth, A. Bondeau, W. Cramer, J,O. Kaplan, S. Levis, W. 

Lucht, M.T., et al. (2003). Evaluation of ecosystem dynamics, plant geography and terrestrial 

carbon cycling in the LPJ dynamic global vegetation model. Global Change Biology 9:161-185. 

Soulé, M.E., editor. 1986. Conservation Biology: the science of scarcity and diversity. Sinauer 

Associates, Inc. Sunderland, MA. 

Steel, Z.L., M. Wilkerson, P. Grof-Tisza, and K. Sulzner. 2011. Assessing species and area 

vulnerability to climate change for the Oregon Conservation Strategy: Willamette Valley 

Ecoregion. Conservation Management Program, University of California, Davis, CA. 

Stein, B.A., P. Glick, N. Edelson, and A. Staudt (editors). 2014. Climate-Smart Conservation: Putting 

Adaptation Principles into Practice. National Wildlife Federation, Washington, D.C. 

http://www.nwf.org/pdf/Climate-Smart-Conservation/NWF-Climate-Smart-Conservation_5-08-

14.pdf. 

Stephens, J.L., K. Kreitinger, C.J. Ralph, and M.T. Green. 2011. Informing Ecosystem Management: 

Science and Process for Landbird Conservation in the Western United States. Biological 

Technical Publication BTP-R1014-2011. 

Surasinghe, T.D., J.R. Couter, R.F. Baldwin, and R.J. Johnson. 2012. Use of threat-analysis to assess 

the effects of land development on biodiversity in a Blue Ridge-Piedmont landscape. Journal of 

Conservation Planning 8:1-11. 

Tague, C., G. Grant, M. Farrell, J. Choate, and A. Jefferson. 2008. Deep groundwater mediates 

streamflow response to climate warming in the Oregon Cascades. Climatic Change 86 (1):189-

210. 

Taft, O.W., and S.M. Haig. 2003. Historical wetlands in Oregon’s Willamette Valley: implications 

for restoration of winter waterbird habitat. Wetlands 23:51-46 

The Intertwine Alliance. 2012a. Regional Conservation Strategy for the Greater Portland-Vancouver 

Region (A. Sihler, editor). The Intertwine Alliance, Portland, OR. 

The Intertwine Alliance. 2012b. Biodiversity Guide for the Greater Portland-Vancouver Region (A. 

Sihler, editor). The Intertwine Alliance, Portland, OR. 

The Nature Conservancy (TNC). 2012. Willamette Basin Synthesis Project Map (created 2008, 

updated 2012). 
Willamette Valley Conservation Study

Appendix J. Literature Cited J-11

Theobald, D.M. 2005. Landscpae Patterns of Exurban Growth in the USA from 1980 to 2020. 

Ecology and Society 10(1):32. http://www.ecologyandsociety.org/vol10/iss1/art32/

Thilenius, J.F. 1968. The Quercus garryana forests of the Willamette Valley, Oregon. Ecology 

49:1124-1133. 

Thorson, T.D., S.A. Bryce, D.A. Lammers, A.J. Woods, J.M. Omernik, J. Kagan, D.E. Pater, and 

J.A. Comstock. 2003. Ecoregions of Oregon (poster/map). U.S. Geology Survey, Reston, VA. 

Traill, L.W., B.W. Brook, R.R. Frankham, and C.J.A. Bradshaw. 2010. Pragmatic population 

viability targets in a rapidly changing world. Biological Conservation 143:28-34. 

Trombulak, S.C., and C.A. Frissell. 2000. Review of ecological effects of roads on terrestrial and 

aquatic communities. Conservation Biology 14:18–30. 

U.S. Fish and Wildlife Service, and U.S. Department of Commerce, U.S. Census Bureau. 2011. 

National Survey of Fishing, Hunting, and Wildlife-Associated Recreation. 

U.S. Fish and Wildlife Service (USFWS). 1993a. Endangered and Threatened Wildlife and Plants; 

Determination of Threatened Status for the Plant “Sidalcea nelsonianna” (Nelson’s checkermallow). 58 FR 8235. 

U.S. Fish and Wildlife Service (USFWS). 1997. Endangered and Threatened Wildlife and Plants; 

Determination of Threatened Status for Castilleja levisecta (Golden Paintbrush). 62 FR 31740. 

U.S. Fish and Wildlife Service (USFWS). 1998a. Endangered and Threatened Wildlife and Plants; 

Final Endangered Status for Lomatium bradshawii (Bradshaw’s lomatium). 53 FR 38448. 

U.S. Fish and Wildlife Service (USFWS). 1999. Endangered and Threatened Wildlife and Plants; 

Determination of Threatened Status for Bull Trout in the Coterminous United States; Final Rule 

Notice of Intent To Prepare a Proposed Special Rule Pursuant to Section 4(d) of the Endangered 

Species Act for the Bull Trout; Proposed Rule. 64 FR 5891. 

U.S. Fish and Wildlife Service (USFWS). 2000. Endangered and Threatened Wildlife and Plants; 

Endangered Status for Erigeron decumbens var. decumbens (Willamette Daisy) and Fender’s Blue 

Butterfly (Icaricia icarioides fenderi) and Threatened status for Lupinus sulphureus ssp. kincaidii

(Kincaid’s Lupine). 65 FR 3875. 

U.S. Fish and Wildlife Service (USFWS). 2008a. Strategic habitat conservation handbook: a guide to 

implementing the technical elements of strategic habitat conservation (Version 1.0). A report from 

the National Technical Assistance Team. February 11, 2008. 

U.S. Fish and Wildlife Service. 2008b. Birds of Conservation Concern 2008. USFWS, Division of 

Migratory Bird Management, Arlington, VA. http://www.fws.gov/ migratorybirds/ 

U.S. Fish and Wildlife Service (USFWS). 2010a. Recovery Plan for the Prairie Species of Western 

Oregon and Southwest Washington. USFWS, Portland, OR. 

U.S. Fish and Wildlife Service (USFWS). 2011a. Comprehensive Conservation Plan for the 

Willamette Valley National Wildlife Refuge Complex. 

U.S. Fish and Wildlife Service (USFWS). 2011b. Birds of Management Concern and Focal Species. 

USFWS, Migratory Bird Program. November 2011. 

U.S. Fish and Wildlife Service (USFWS). 2012. Draft Guidance on Selecting Species for Design of 

Landscape-scale Conservation. July 20, 2012. 
Willamette Valley Conservation Study 

J-12 Appendix J. Literature Cited 

U.S. Fish and Wildlife Service (USFWS). 2013a. Tualatin River National Wildlife Refuge 

Comprehensive Conservation Plan. Tualatin, OR. 

U.S. Fish and Wildlife Service (USFWS). 2013b. Determination of Endangered Status for the 

Taylor's Checkerspot Butterfly and Threatened Status for the Streaked Horned Lark; Final Rule. 

78 FR 61451. 

U.S. Fish and Wildlife Service (USFWS). 2013c. Land Protection Plan, Bear River Watershed 

Conservation Area. USFWS, Lakewood, CO. 

U.S. Fish and Wildlife Service (USFWS). 2103d. A Landscape-scale Approach to National Wildlife 

Refuge System Planning. 

U.S. Fish and Wildlife Service (USFWS). 2014a. Strategic Conservation Management in Oregon’s 

Willamette Valley: Surrogate Species Pilot 1.0. Portland, OR. 

U.S. Fish and Wildlife Service (USFWS). 2014b. Waterfowl population status, 2014. USFWS, 

Washington, DC. 

U.S. Fish and Wildlife Service (USFWS). 2014c. Endangered and Threatened Wildlife and Plants; 

Determination of Threatened Status for the Western Distinct Population Segment of the Yellowbilled Cuckoo (Coccyzus americanus). 79 FR 59992. 

U.S. Fish and Wildlife Service (USFWS) and U.S. Geological Survey (USGS). 2004. Writing Refuge 

Management Goals and Objectives: A Handbook. 

U.S. Forest Service. 1995. Sandy River Delta Plan, Columbia River Gorge National Scenic Area. 

Prepared by David Evans and Associates, Inc., Portland, OR. 

Van Horne, B. 1983. Density as a misleading indicator of habitat quality. Journal of Wildlife 

Management 47:893-901. 

Vesely, David G. 2011. A Guide to Conserving Wildlife on Willamette Valley Farms. Oregon 

Wildlife Institute. Corvallis, OR. 

Vesely, David G. and Daniel K. Roseburg. 2010. Wildlife Conservation in the Willamette Valley’s 

Remnant Prairies and Oak Habitats: A Research Synthesis. Oregon Wildlife Institute. Corvallis, 

OR. 

Western Governors’ Wildlife Council (WGWC). 2013. Western Governors’ Crucial Habitat 

Assessment Tool (CHAT): vision, definitions and guidance for state systems and regional viewer. 

http://www.westgovchat.org 

Whelan, C.J., D.G. Wenny, and R.J. Marquis. 2008. Ecosystem services provided by birds. Ann. 

N.Y. Acad. Sci. 1134:25-60. 

Wilson, T.S., B.M. Sleeter, R.R. Sleeter, and C.E Soulard. 2014. Land use threats and protected 

areas: a scenario-based landscape level approach. Land 3(2):362-389 

Willamette Restoration Initiative (WRI). 2001. The Willamette Restoration Strategy. Willamette 

River Initiative. Portland, OR. 

Wilson, Tamera S., Benjamin M. Sleeter, Rachel R. Sleeter, and Christopher E. Soulard. 2014. Landuse threats and protected areas: a scenario-based, landscape level approach. Land 3:362-389. 

Young, B., E. Byers, K. Gravuer, K. Hall, G. Hammerson, and A. Redder. 2010. Guidelines for 

Using the NatureServe Climate Change Vulnerability Index: Release 1.2. NatureServe. 
Willamette Valley Conservation Study 

Appendix K. Planning Team    K-1 

Appendix K. Planning Team 

Charles Houghten U.S. Fish and Wildlife Service, Refuges 

Kevin O’Hara U.S. Fish and Wildlife Service, Refuges 

Tom Miewald U.S. Fish and Wildlife Service, Refuges 

Mike Marxen U.S. Fish and Wildlife Service, Refuges 

Liz Cruz U.S. Fish and Wildlife Service, Refuges 

Damien Miller U.S. Fish and Wildlife Service, Refuges 

Erin Holmes U.S. Fish and Wildlife Service, Refuges 

Joe Engler U.S. Fish and Wildlife Service, Refuges 

Jim Houck U.S. Fish and Wildlife Service Refuges, Retired 

Steve Smith U.S. Fish and Wildlife Service Refuges, Retired 

Scott McCarthy U.S. Fish and Wildlife Service, Refuges, Retired 

Jock Beal U.S. Fish and Wildlife Service Refuges, Retired 

Doug Spencer U.S. Fish and Wildlife Service Refuges, Retired 

Mike Green U.S. Fish and Wildlife Service, Migratory Birds 

Joe Sands U.S. Fish and Wildlife Service, Migratory Birds 

Mikki Collins U.S. Fish and Wildlife Service, Ecological Services 

Cat Brown U.S. Fish and Wildlife Service, Ecological Services 

Jeff Dillon U.S. Fish and Wildlife Service, Ecological Services 

Jarod Jebousek U.S. Fish and Wildlife Service, Partners for Fish and Wildlife 

Chris Seal U.S. Fish and Wildlife Service, Partners for Fish and Wildlife 

Sam Lohr U.S. Fish and Wildlife Service, Fisheries 

Christina Wang U.S. Fish and Wildlife Service, Fisheries 

Joan Haggar U.S. Geological Service 

Kathy Pendegrass Natural Resource Conservation Service 

Ann Kreager Oregon Department of Fish and Wildlife 

Sue Belke Oregon Department of Fish and Wildlife 

Susan Barnes Oregon Department of Fish and Wildlife 

AnnMary Meyers Oregon Department of Fish and Wildlife 

Rebecca Currin Oregon Department of Agriculture 

Bob Altman American Bird Conservancy 

Jimmy Kagan Institute for Natural Resources 

Sue Vrilakas Institute for Natural Resources 

Tom Kaye Institute for Applied Ecology 

Dana Ross Institute for Applied Ecology 

Greg Fitzpatrick Fitzpatrick Ecological Consulting 

Dan Bell The Nature Conservancy 

Michael Schindel The Nature Conservancy 

Cheryl Schultz, Ph.D. Washington State University 

Dave Hulse, Ph.D. University of Oregon 

Madeline Steele SWCA Environmental Consultants 

John Bauer The Wetlands Conservancy 

 
Willamette Valley Conservation Study 

K-2 Appendix K. Planning Team 

U.S. Department of the Interior

U.S. Fish & Wildlife Service

National Wildlife Refuge System Lands Division

911 N.E. 11th Avenue

Portland, OR 97232-4181

https://www.fws.gov/yourwillamettevalley/index.html

National Wildlife Refuge System Information

1 800/344 WILD

March 2017

The mission of the U.S. Fish & Wildlife Service

is working with others to conserve, protect, and

enhance fish, wildlife, and plants and their

habitats for the continuing benefit of the

American people.

Cover Photo:

Willamette Valley panorama

©Don Hankins