Coastal Marten Project

Coastal martens, a distinct population segment of the Pacific marten and analogous to the Humboldt marten, are a squirrel-sized weasel that historically occurred from the northern border of Oregon to Sonoma County in California. The contemporary distribution of coastal martens appears to be substantially reduced and facing multiple threats. Population declines were so severe that coastal martens were considered extremely rare or extirpated until the mid-1990’s when martens were detected by researchers in northwestern California. Consequently, the coastal marten is federally listed as threatened, is listed as state endangered in California, and is a species of Greatest Conservation Need in Oregon and California.

Additional survey efforts were conducted throughout the 2010’s, expanding the understanding of contemporary marten distribution to include four geographically isolated populations. Despite advancements in our understanding of Humboldt marten distribution in northern California and southern Oregon, many critical data gaps remain.

We are collaborating with state and federal agencies, tribal communities, private-industry partners, and other academic researchers to better define the geographic extent and connectivity of these putative marten populations. Documenting underlying variation in habitat associations, demography, and genetic composition of coastal martens within populations will facilitate assessments of resiliency, redundancy, and representation that are needed to understand the vulnerability of martens to compounding threats of climate change, altered disturbance regimes, and habitat fragmentation and to implement effective recovery actions.

Hoopa Fisher Project

Female fishers give birth and raise their offspring in cavities in live trees and standing-dead trees. Fishers do not excavate cavities, but rather depend on fungal-decay processes or cavity-excavating species (e.g., piliated woodpeckers). Selection of habitat characteristics by reproductive females can mediate the influence of adverse environmental conditions on the fitness of offspring. Previous research has suggested that cavities and burrows used for reproduction by cavity-obligate species offer thermoregulatory benefits, access to prey, and can limit predation pressure.

In close collaboration with the Hoopa Valley Tribe, we hypothesized that female fishers select particular characteristics of reproductive den cavities at discrete stages of offspring development to mediate adverse biotic and environmental effects on their offspring.

We found that natal and early-maternal dens buffered minimum temperatures significantly more than late-maternal dens and cavities used during the nonreproductive season. A male fisher skull was also less likely to fit through the cavity openings of natal dens than through the openings of cavities used by adult females during the nonreproductive season. Litter survival was significantly lower at natal dens than at late-maternal dens. The age of adult female fishers did not affect the probability of litter survival. Our results emphasize the vulnerability of vertebrate offspring during early developmental periods and how cavity-obligate species select cavities to mediate environmental conditions during reproduction (Matthews et al. 2019).

Hoopa Ringtail Project

Ringtails, the smallest member of the raccoon family, is a species of conservation concern in California and Oregon, yet little is known about their basic ecology in the northwestern edge of their distribution. Diurnal rest sites, such as cavities in live and standing-dead trees, are an essential habitat element for ringtails and co-occurring mesocarnivores. Ringtails use diurnal rest sites as shelter during adverse weather conditions, refugia from predators, such as the co-occurring fisher, and dens to raise young.

We collaborated with the Hoopa Valley Tribe and Humboldt State University to better understand the forest conditions associated with rest sites selected by ringtails can inform forest management practices. Using data collected via radio telemetry, we found that ringtails were more likely to select rest sites in mature older forests compared to oak woodland and open areas and were less likely to select rest sites closer to perennial water sources. We did not detect an effect of fishers on the selection of rest sites. These results indicate that both late- and some early-seral forest conditions provide suitable habitat for ringtail rest sites and ultimately demonstrate that ringtails use a mosaic of seral stages in the forests of the Pacific Northwest (Gundermann et al., 2023).

In the news

• BNN Correspondents. 2024. Unlocking the mysteries of the ringtail: A groundbreaking study in California's Hoopa Valley. BNN. February 24. Read the article.
• Lundeberg, S. 2024. Study provides rare glimpse of the ringtail, an important but poorly understood predator. Oregon State University Newsroom. February 24. Read the article.

Kings River Fisher Project

Fishers are known to have large home ranges for their body size and are commonly associated with features of older trees and forests. These patterns can vary across geographic areas due to factors such as prey type/availability, forest composition/management history, climatic patterns, and presence of competitors/predators. Thus, to provide accurate information for forest management, it is important to quantify the size and composition of home ranges and core areas at regional and local scales when possible. This is especially true at the southernmost extent of the fisher distribution in the southern Sierra Nevada, where fishers are federally endangered and conditions differ from areas where fishers occur further north and east. The southern Sierra has also experienced unprecedented drought, tree mortality, and wildfire activity in recent years.

We found fishers frequently used areas of live forest and areas affected by tree mortality while selecting against warmer areas, areas further from streams, and areas along ridges. Following a period of wide-spread tree mortality, fishers started strongly avoiding non-forested areas. Variation in individual-level fisher selection was greatest during drought and tree mortality periods. A manuscript for this project is in preparation.

Gifford Pinchot Fisher and Marten Project

The conservation of forest-obligate carnivores is a pressing priority for land managers, regulatory agencies, and tribal communities in the Pacific Northwest following decades of unregulated trapping for fur, predator-control campaigns, and habitat loss related to logging and development. The consequences of a changing climate threaten to further affect species persistence through decreasing snow packs, increasing wildfire frequency and severity, and changing forest-pathogen dynamics. Two species of particular conservation concern in the Pacific Northwest are fishers and martens. Fishers were extirpated from Washington and from all but southern Oregon by the mid-1900s and martens are expected to suffer range contractions and further population declines as high-elevation forests are altered by a changing climate.

As a conservation measure for fisher, the Washington Department of Fish and Wildlife and partners reintroduced fishers from central British Columbia to the Gifford Pinchot National Forest in the southern Cascade Mountains of Washington between 2015 and 2017. However, the success of this effort is unknown. Fishers are a predator of marten and directly compete with them. The effect of the fisher reintroduction effort on marten populations remains unexplored.

We surveyed for fishers and martens with remote cameras between 2019 and 2021 to estimate their distribution, co-occurrence, and habitat relationships. We are currently identifying species photographed by the remote cameras and modeling species detection data.

Klamath Plateau Fisher Project

Female fishers give birth and raise their offspring in cavities in live trees and standing-dead trees. Fishers do not excavate cavities, but rather depend on fungal-decay processes or cavity-excavating species (e.g., piliated woodpeckers). Selection of habitat characteristics by reproductive females can mediate the influence of adverse environmental conditions on the fitness of offspring. Previous research has suggested that cavities and burrows used for reproduction by cavity-obligate species offer thermoregulatory benefits, access to prey, and can limit predation pressure.

In close collaboration with the Hoopa Valley Tribe, we hypothesized that female fishers select particular characteristics of reproductive den cavities at discrete stages of offspring development to mediate adverse biotic and environmental effects on their offspring.

We found that natal and early-maternal dens buffered minimum temperatures significantly more than late-maternal dens and cavities used during the nonreproductive season. A male fisher skull was also less likely to fit through the cavity openings of natal dens than through the openings of cavities used by adult females during the nonreproductive season. Litter survival was significantly lower at natal dens than at late-maternal dens. The age of adult female fishers did not affect the probability of litter survival. Our results emphasize the vulnerability of vertebrate offspring during early developmental periods and how cavity-obligate species select cavities to mediate environmental conditions during reproduction (Matthews et al. 2019).

Oregon Fisher Recovery Project

Fishers were once widely distributed across the forested portions of western Oregon. Today, fishers occupy approximately 15% of their former distribution between the west slope of the Oregon Cascades and the Pacific Ocean. The reintroduction of fishers to suitable, formerly-occupied portions of their historical range have contributed to significant range expansions in New England and the Great Lakes regions. Preliminary results from the reintroduction of fishers to Washington and California indicate that populations are becoming established, and that these actions are necessary for recovering fishers in the West Coast. The establishment and persistence of a reintroduced population of fishers to the Oregon Cascades will be contingent on a sustained, collaborative partnership between state and federal agencies, tribal communities, private-industry partners, academic institutions, and conservation stakeholders.

We collaboratively investigated the feasibility of reintroducing fishers in Oregon and concluded that unoccupied portions of the historical distribution of fishers in the southern Oregon Cascades could support a reintroduced fisher population (Matthews et al. 2021). We are working with partners to further investigate potential levels of predation and competitive pressure on fishers as well as available prey resources necessary to meet energetic needs.

West Coast Fisher Distribution Modeling Project

Fishers are a medium-sized carnivore of conservation concern in portions of their distribution. Fishers in the southern Sierra Nevada are federally threatened and other populations have been evaluated for federal listing on several occasions. Small and isolated populations are the most immediate and challenging threat to fisher persistence in Washington, Oregon and California.

Species distribution, habitat associations, and population size are critical information needs for species recovery. Fisher distribution patterns and habitat associations have been evaluated using presence-only and expert opinion models. These models frequently fail to meet assumptions (e.g., representative sampling, constant detection probabilities); increasing calls for analyses in detection-non detection frameworks.

We are modeling the distribution, habitat associations, and population sizes of fisher across Washington, Oregon, and California. We are developing a hierarchical model of detection-non detection data using occupancy and integrated modeling to estimate these important parameters. Our results will be a useful decision-support tool to promote species recovery in the face of stochastic events and a changing climate.

Yosemite, Sequoia, and Kings Canyon Fisher Project

Fishers are a medium-sized carnivore listed as federally endangered in the southern Sierra Nevada Mountains. Small and isolated populations are the most immediate and challenging threat to fisher persistence. Understanding species distribution and habitat associations are critical information needs for species recovery and conservation. In collaboration with National Park Service partners, we are modeling the distribution and habitat associations of fishers in Yosemite, Sequoia, and Kings Canyon National Parks to assist with ongoing conservation and management efforts. We are developing a hierarchical model of detection-non detection data using occupancy and habitat modeling to estimate the distribution and habitat associations of fisher. We will use these predicted associations to forecast the effects of differing management scenarios and stochastic effects on fishers within the National Parks. Our results will be a useful decision-support tool to promote species recovery in the face of stochastic events and a changing climate.

Klamath-Siskiyou Carnivore Project

A century of fire suppression and a changing climate have resulted in increasingly frequent and severe wildfires in the western United States. These conditions have created challenging circumstances for the sustainable management of forest and cultural resources and the conservation of forest-dependent wildlife species. Although many forest-dependent species evolved in fire-prone landscapes, changing fire regimes are recognized as a threat to the persistence of fishers. Fishers were consequently listed as federally-endangered and state-threatened in a portion of California and are a Species of Greatest Conservation Need in California, Oregon, and Washington.

We are partnering with federal, state, Tribal, private-industry, non-profit, and academic partners to fill key information gaps on the effects of wildfire and fuels management on fishers and co-occurring wildlife. Our history of annually monitoring fishers on the Klamath National Forest and neighboring private timberlands in northern California and southern Oregon since 2006 provides long-term data needed to discern the potential population-level effects of wildfire, fuels treatments, and conservation actions. For example, our work on fishers provided the opportunity to investigate the effects of removing approximately 20% of the population to reintroduce them to an unoccupied portion of their historical distribution in the northern Sierra Nevada Mountains between 2009 and 2011 (Green et al. 2018). We also investigated the effects of the mixed-severity 2014 Beaver Fire and short-term effects of post-fire management (e.g., salvage logging, replanting) on this population of fishers (Green et al. 2022). We are currently investigating the effects of fuels management and the 2022 McKinney Fire.

Northern Sierra Fisher Reintroduction Project

Understanding if fishers can persist in forests that are managed for timber production is an important area of research. Evaluations of fisher population viability on managed landscapes, however, have received surprisingly little attention, even though they may play an important role in fisher recovery. Forests in the western United States available for fisher recolonization include extensive landscapes managed for timber production. Though fishers can occupy and reproduce in these forests, large-scale harvest of late-successional forests were also some of the primary causes for fisher population decreases across North America. Thus, understanding whether fisher populations can persist in systems used for timber production is imperative to their conservation.

We used a reintroduction of fishers to a privately-owned forest managed for timber production in northern California to experimentally evaluate the viability of a fisher population on a landscape managed for timber production. We studied this reintroduced population of fishers for 8 years using annual live-captures and year-round tracking with radio telemetry. Using population modeling with spatial capture-recapture methods, we estimated this population of fishers to be growing during the study period. The density of the reintroduced fisher population in 2017 (10.8 fishers/100 km2) was within the reported range of fisher densities across the western United States. The reintroduction of fishers to previously occupied portions of their range is an important component of fisher conservation and will play a role in the recovery of the species in western portions of the fisher’s range. Our results suggest that forests managed for timber production with landscape conditions similar to our study area may be important for future fisher reintroductions and species recovery (Green et al. 2022).

Pacific Northwest Porcupines Project

North American porcupines have a broad geographic distribution across much of the continent, but recent evidence suggests that their populations may be declining in some areas, including the Pacific Northwest. Estimating baseline historical and contemporary distributions of Porcupines is necessary for initiating monitoring efforts and, if necessary, informing strategic conservation actions. We collaborated with Humboldt State University to compile occurrence records of porcupines in Washington, Oregon, and California from 1908 to 2018. We modeled the historical and contemporary distributions of porcupines and found a recent shift in the occupied environmental niche of porcupines in the Pacific Northwest away from forested areas and towards desert scrub and grassland vegetation communities (Appel et al. 2021).

We are also collaborating with Humboldt State University, Rogue Detection Teams, and the Levi Lab at Oregon State University to evaluate the effectiveness of non-invasive survey methods for porcupine. Methods include sodium-soaked wood blocks, non-invasive genetic sampling, and scat-detection teams.

Portland Urban Coyote Project

Coyotes are charismatic animals that often evoke excitement when encountered by people in urban areas. The Portland Urban Coyote Project capitalizes on this excitement and uses education, outreach, and research to improve habitat for urban wildlife, increase awareness of the importance of coyotes for ecosystem sustainability, and reduce negative interactions between coyotes and people. We use community science to document patterns in human-coyote interactions in Washington, Multnomah, and Clackamas Counties. Coyotes are an important component of many urban landscapes and are a compelling conduit for people in urban areas to observe, appreciate, and conserve wildlife.

We are collaborating with Portland State University, Portland Audubon, Willamette River Keepers, the Tualatin Soil and Water Conservation District, and the Oregon Department of Fish and Wildlife to analyze patterns in human perceptions in over 5,000 community-reported interactions with coyotes. We are also developing virtual and hands-on learning opportunities to present to community members using results from our analyses. For additional information please visit our project website.

Sierra Nevada Red Fox

The Sierra Nevada red fox is a rare and endangered subspecies of red fox limited to upper montane forests, subalpine, and alpine environments of California and Oregon. Updated information on its contemporary distribution and density is needed to guide and evaluate conservation and management actions.

We combined 12 years (2009–2020) of detection and non-detection data collected throughout California and Oregon to model the potential distribution and density of Sierra Nevada red foxes throughout their historical and contemporary ranges. We estimated a density of approximately one fox per 100 km2 distributed throughout 22,926 km2 in three distinct regions of California and Oregon–Sierra Nevada, Lassen Peak, and Oregon Cascades. Sierra Nevada red foxes were most likely to be found in areas with low minimum temperatures and high snow water equivalent. Our results provided a contemporary baseline to inform the development and evaluation of conservation and management actions, and guide future survey efforts (Green et al. 2023).

Southern Sierra Nevada Carnivore Project

California experienced a severe drought from 2012-2015 which led to a massive bark beetle outbreak in the water stressed trees. It has been estimated that this led to the death of over 100 million trees with the majority located in the central and southern Sierra Nevada. This tree mortality and drought contributed to severe fire conditions and in 2021 and 2022 the SSN experienced a series of uncharacteristically large and severe wildfires that combined burned over 2,670 km2.

Both the tree mortality and subsequent wildfires represent major disturbance events that have the potential to profoundly affect wildlife populations. Concerns about these ecological disturbances are particularly acute for the federally endangered southern Sierra Nevada fisher population. The ways that these dramatic changes in forest composition may impact fisher, and other forest dependent mammals, are complex and varied may result in significant changes to their abundance and spatial distribution.

We are collaborating with the U.S. Forest Service Region 5 Carnivore Monitoring Program to model the response of the southern Sierra Nevada fisher population to the widespread tree mortality and subsequent large-scale wildfires. This project will provide the information needed to make informed decisions regarding the conservation and restoration of healthy, diverse, and resilient ecosystems.

Yosemite Alpine Carnivore Community Project

Many populations of carnivores have been declining on account of a variety of stressors. Climate change poses particular risks to alpine and subalpine ecosystems. Research into the impacts of climate change is frequently focused on single species, thus there is a lack of information about alpine and subalpine community dynamics in the face of climate change.

We are collaborating with Yosemite National Park to model the occupancy patterns and diet composition of members of the alpine and subalpine community within the park. We are using a combination of remote cameras to photograph species and scat-detection dogs to find scat to identify to species. Our research will provide additional insights to the carnivore community dynamics in these high-elevation areas that are expected to experience some of the most dramatic changes due to climate change.

Yosemite Cougar Project

The cougar is the most widely distributed wild mammal in the western hemisphere and occurs in a variety of biomes. Despite their widespread distribution, cougars can be difficult to study at broad geographic scales because they exhibit large home ranges, wide-ranging movement patterns, and low population densities. Thus, little is empirically known about the abundance or density of cougars in remote and less-developed areas, and whether these areas might support higher cougar densities than developed or fragmented landscapes.

In the Sierra Nevada of California, cougars are thought to be declining and occur within and interact with a diverse ecological community that includes a suite of other species of conservation interest. Clarifying the density and distribution of cougars, including how landscape structure influences their occurrence, may both inform their conservation and mitigate potential negative effects on other species of conservation concern.

We collaborated closely with Yosemite National Park, Rogue Detection Teams, and the Mammalian Ecology and Conservation Unit at the University of California Davis to estimate the abundance, density, and distribution of cougars in Yosemite National Park. We modeled spatial encounter data collected in 2019 and 2020 from DNA-based individual identification of scats with detection count data derived from remote cameras to estimate cougar density and detection probability.

We estimated there to be 31 cougars in Yosemite, with higher densities associated with productive, vegetated areas. We found detection probability by scent detection teams was higher for females than males and positively correlated with survey effort, proximity to trails, and distance farther from roads and streams. Our study illustrates the utility of noninvasive survey methods that yield individual identities in rugged and remote environments, where capture and handling of cryptic, low-density animals is logistically challenging and cost prohibitive (Martin et al. In Press).

Yosemite Raccoon Project

Managing human-wildlife incidents dominates the attention and resources of many wildlife management programs. National Parks in the United States have a long history with human-wildlife interactions and conflicts. Improvements in communication with visitors, food-storage infrastructure, regulation enforcement, and the management of habituated and food-conditioned animals have led to decreases in human-wildlife conflicts. Yosemite National Park is well known for its history of human-bear conflicts but in the Yosemite Valley portion of Yosemite National Park, conflicts with raccoons now outnumber those with black bears. Like bears, raccoons pose a risk of property damage and injury to humans, but they also pose a risk of zoonotic disease transmission and a risk of predation to species of conservation concern.

To better understand the behavior and ecology of Yosemite Valley raccoons and to inform future management efforts aimed at reducing these potential negative outcomes, we collaborated with Yosemite National Park to evaluate the influence of anthropogenic food availability on raccoon space use using global positioning system tracking collars. We collected a mean (SD) of 555 (349) locations on 11 raccoons (7M, 4F) between December 2016 and May 2018 and developed a resource selection model to evaluate selection by raccoons within their home ranges in Yosemite Valley.

Raccoons were located more frequently in developed areas (i.e., areas with structures or other capital projects) of Yosemite Valley compared to undeveloped areas and showed a stronger selection pattern for developed areas where people gathered for consuming food (e.g., picnic areas, campgrounds). Leveraging the successful strategies for managing human-bear interactions and adapting management to accommodate the ecology and behaviors of raccoons and other species involved in human-wildlife conflict will offer a foundation for a holistic human-wildlife interaction program in our National Parks (Anderson et al. In Press).