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USGS2025

Triangulating habitat suitability for the locally extirpated California grizzly bear

Reintroducing locally extirpated wildlife species is often necessary to meet recovery goals. However, because current field data cannot be gathered about these species, efforts to identify suitable habitat are often complicated and controversial. Here we present a case study examining a novel approach for identifying suitable habitat for the locally extirpated brown bear, known as the “grizzly,” in California, USA. Once home to a large population of grizzlies, the last credible sighting of a grizzly in California was in 1924, but recent discussions have explored a reintroduction. To study potential grizzly bear habitat suitability in California, we use a multi-model approach in which we consider three indirect methods, or “analogies,” each of which incorporates both environmental and social variables. In the “historical analogy,” we used a unique record of human encounters and museum specimens to build a habitat model of grizzlies in California 150 years ago. In the “geographic analogy,” we used data about contemporary brown bears in Europe and North America to identify potential suitable habitat in California. In the “taxonomic analogy,” we examined data from other large carnivores currently extant in California to draw conclusions about grizzlies. Because these methods yield varying results, we adopt a process known in the social sciences as “triangulation” to compare them. We show that a triangulation approach can improve our understanding of potential suitable habitat, clarifying the strengths and weaknesses of various methods and producing robust yet conservative estimates. Our findings suggest that large areas of suitable habitat for grizzlies exist in California. However, we note that place-based social science research and long-term investment in co-existence would be necessary to maintain suitability. The “analogy and triangulation” approach demonstrates the value of multi-model approaches for habitat suitability, especially for reintroductions.

California↗

USGS2024

Population genetics of museum specimens indicate decreasing genetic resiliency: The case of two bumble bees of conservation concern

Genetic resiliency is the likelihood that populations retain sufficient genetic diversity to respond to environmental change. It is rarely examined through time in conservation genetic studies due to challenges of acquiring and sequencing historical specimens. Focusing on populations of two sibling bumble bee species of conservation concern with different recent patterns of decline, we used museum specimens collected between 1960 and 2020 and 15 microsatellite markers to assess genetic resiliency (allelic richness, expected heterozygosity, and inbreeding) through time and across geographic space. We find evidence of decreasing allelic richness through time, starting at least 30 years before observed abundance declines in one species and at least 20 years before present in a species with apparently stable abundance. We also found increasing expected heterozygosity through time, indicating increased inbreeding, in the putatively stable species. We demonstrate that genetic measurements taken from specimens collected through time can be used to detect population decline in imperiled species before decreases in abundance are detected. We also demonstrate the importance of interpreting population genetic metrics within the context of historical patterns to assess species' conservation statuses. Finally, we discuss the limitations of currently available population genetic methods, including the influence of isolation by distance and sampling density on measurements of genetic structure, and the influence of demographic characteristics and choice of genetic markers on estimates of genetic diversity and structure. We call for further development of individual-based modeling methods to measure genetic structure, as opposed to commonly applied population-based metrics, to overcome these limitations.

Biological Conservation↗

USGS2023

A hidden cost of single species management: Habitat-relationships reveal potential negative effects of conifer removal on a non-target species

Land management priorities and decisions may result in population declines for non-target wildlife species. In the western United States, large-scale removal of conifer from sagebrush ecosystems ( Artemisia spp.) is occurring to recover greater sage-grouse ( Centrocercus urophasianus ) populations and may result in pinyon jay ( Gymnorhinus cyanocephalus ) habitat loss. Jay populations have experienced long-term declines, due to unknown causes, resulting in a recent petition for listing under the Endangered Species Act of 1973. We developed a Bayesian hierarchical model of jay abundance, using 13 years of point count data (2008–2020) collected across the western United States, to estimate regional population trends, model habitat requirements, assess conifer removal effects on jays, and generate hypotheses regarding jay population declines. Our model included climate and landcover covariates and regional trends in pinyon jay density. We applied our modeled habitat relationships to map predicted pinyon jay density, given 2008 and 2020 resource conditions, and map density changes from 2008 to 2020. Our results indicate pinyon jay populations are declining within Bird Conservation Region 16. Jay density was positively associated with sagebrush cover, Palmer Drought Severity Index, and pinyon-juniper cover. Conversely, jay populations were negatively associated with Normalized Difference Vegetation Index (NDVI). We found higher pinyon jay densities within locations possessing both sagebrush and pinyon-juniper cover; conditions characteristic of phase I and II conifer encroachment which are preferentially targeted for conifer removal to restore sagebrush communities. Conifer removal, if conducted at locations with high pinyon jay densities, is therefore likely to negatively affect jay abundance.

Arizona, California, Colorado, Idaho, Kansas, Mont↗

USGS2021

Social identity, values, and trust in government: How stakeholder group, ideology, and wildlife value orientations relate to trust in a state agency for wildlife management

Our objective was to understand how social identity and values influenced general public and stakeholder trust in a state wildlife management agency (SWMA). In particular, we wanted to examine how stakeholder group, political ideology, and wildlife value orientation influenced trust in a SWMA. Data were derived from a study of state residents, hunters and livestock producers related to wolf management. Results suggest differences in agency trust correlated with all three factors and the interaction between stakeholder group and wildlife value orientation. Livestock producers reported lower levels of trust in the agency, compared to hunters and the general public. Individuals with conservative or middle-of-the-road ideologies reported less trust in the agency than individuals with a liberal ideology did. Respondents with traditional wildlife values also had less trust in the agency compared to mutualist, pluralist, and distanced respondents. Results suggested similarities in the ideologies and wildlife value orientations of livestock producers and hunters, although these groups differed significantly in their trust in the agency. Agencies face the challenge of managing common-pool, public-trust resources for stakeholders who hold different values and ideologies, and who are differentially affected by management decisions.

Minnesota↗

USGS2012

Common coastal foraging areas for loggerheads in the Gulf of Mexico: Opportunities for marine conservation

Designing conservation strategies that protect wide-ranging marine species is a significant challenge, but integrating regional telemetry datasets and synthesizing modeled movements and behavior offer promise for uncovering distinct at-sea areas that are important habitats for imperiled marine species. Movement paths of 10 satellite-tracked female loggerheads ( Caretta caretta ) from three separate subpopulations in the Gulf of Mexico, USA, revealed migration to discrete foraging sites in two common areas at-sea in 2008, 2009, and 2010. Foraging sites were 102–904 km away from nesting and tagging sites, and located off southwest Florida and the northern Yucatan Peninsula, Mexico. Within 3–35 days, turtles migrated to foraging sites where they all displayed high site fidelity over time. Core-use foraging areas were 13.0–335.2 km 2 in size, in water <50 m deep, within a mean distance to nearest coastline of 58.5 km, and in areas of relatively high net primary productivity. The existence of shared regional foraging sites highlights an opportunity for marine conservation strategies to protect important at-sea habitats for these imperiled marine turtles, in both USA and international waters. Until now, knowledge of important at-sea foraging areas for adult loggerheads in the Gulf of Mexico has been limited. To better understand the spatial distribution of marine turtles that have complex life-histories, we propose further integration of disparate tracking data-sets at the oceanic scale along with modeling of movements to identify critical at-sea foraging habitats where individuals may be resident during non-nesting periods.

Florida↗

USGS2013

Conservation status of freshwater gastropods of Canada and the United States

This is the first American Fisheries Society conservation assessment of freshwater gastropods (snails) from Canada and the United States by the Gastropod Subcommittee (Endangered Species Committee). This review covers 703 species representing 16 families and 93 genera, of which 67 species are considered extinct, or possibly extinct, 278 are endangered, 102 are threatened, 73 are vulnerable, 157 are currently stable, and 26 species have uncertain taxonomic status. Of the entire fauna, 74% of gastropods are imperiled (vulnerable, threatened, endangered) or extinct, which exceeds imperilment levels in fishes (39%) and crayfishes (48%) but is similar to that of mussels (72%). Comparison of modern to background extinction rates reveals that gastropods have the highest modern extinction rate yet observed, 9,539 times greater than background rates. Gastropods are highly susceptible to habitat loss and degradation, particularly narrow endemics restricted to a single spring or short stream reaches. Compilation of this review was hampered by a paucity of current distributional information and taxonomic uncertainties. Although research on several fronts including basic biology, physiology, conservation strategies, life history, and ecology are needed, systematics and curation of museum collections and databases coupled with comprehensive status surveys (geographic limits, threat identification) are priorities.

Fisheries↗

USGS2001

What is the Ohio Gap Analysis Program (GAP)?

The Gap Analysis Program (GAP) is a program for identifying the degree to which native species and natural communities are represented in present-day conservation lands. Those areas where unique biological communities and conservation lands do not overlap constitute gaps in our conservation effort. GAP aids in the protection of biodiversity through a regional assessment of the conservation status of native species and natural land-cover types. This assessment provides a practical approach based on available data to identify potential conservation areas and strategies. GAP is a preliminary step to the more focused, local studies needed to establish boundaries for potential biodiversity management areas. GAP is conducted as state-level projects and is coordinated by the U.S. Geological Survey (USGS) Biological Resources Discipline (BRD). It is a cooperative effort among regional, state, and Federal agencies and private groups.

Ohio↗

USGS2026

Long lives, short futures: Freshwater turtle and tortoise imports to the United States highlight global trade and conservation challenges

Global trade of freshwater turtles and tortoises presents substantial conservation, biosecurity, and regulatory challenges, particularly for long-lived species that are already highly imperiled. While the United States has historically played a key role in supplying the international chelonian trade, investigations into its role as an importer remain limited. We used import data from the U.S. Fish and Wildlife Service Law Enforcement Management Information System (LEMIS) between 2000 and 2022 to evaluate the trade of freshwater turtles and tortoises. Over 2.5 million individuals were imported into the United States during this period, comprising 172 species that are likely imported for the pet trade, food, and traditional medicine markets. Reported annual imports for freshwater turtles increased until approximately 2013 and decreased thereafter, whereas reported annual imports for tortoises have remained relatively constant. Two species, Chinese softshell turtles ( Pelodiscus sinensis ) and Horsfield's tortoises ( Testudo horsfieldii ) represent 62.9% of all imports. Imported species were largely classified as Vulnerable, Endangered, or Critically Endangered by the IUCN Red List, yet the conservation status of a concerning number of species ( n = 45; 26.2%) has not been evaluated. Many imports appear to be sourced from wild populations (28.3% of freshwater turtles, 71.3% of tortoises); however, captive-sourced imports increased significantly over time across both groups. Import volumes raise concerns regarding the sustainability of freshwater turtle and tortoise trade, the potential for invasive species establishment, and disease spread. Our results highlight the need for updated IUCN assessments, verification of trade records, and strengthening of biosecurity screening at U.S. ports of entry.

Biological Conservation↗

USGS2019

Research priorities for freshwater mussel conservation assessment

Freshwater mussels are declining globally, and effective conservation requires prioritizing research and actions to identify and mitigate threats impacting mussel species. Conservation priorities vary widely, ranging from preventing imminent extinction to maintaining abundant populations. Here, we develop a portfolio of priority research topics for freshwater mussel conservation assessment. To address these topics, we group research priorities into two categories: intrinsic or extrinsic factors. Intrinsic factors are indicators of organismal or population status, while extrinsic factors encompass environmental variables and threats. An understanding of intrinsic factors is useful in monitoring, and of extrinsic factors are important to understand ongoing and potential impacts on conservation status. This dual approach can guide conservation status assessments prior to the establishment of priority species and implementation of conservation management actions.

Biological Conservation↗

USGS2020

A Bayesian framework for assessing extinction risk based on ordinal categories of population condition and projected landscape change

Many at-risk species lack standardized surveys across their range or quantitative data capable of detecting demographic trends. As a result, extinction risk assessments often rely on ordinal categories of risk based on explicit criteria or expert elicitation. This study demonstrates a Bayesian approach to assessing extinction risk based on this common data structure, using three freshwater mussel species being considered for listing under the US Endangered Species Act. The probability that a population is classified under each risk category was modeled as a function of projected landscape change using ordered probit regression, assuming observed categories reflect a latent, continuous probability of persistence. All three species were more likely than not (mean probability >0.5) to be classified as extirpated or low condition throughout their range based on effects of urban development and hydrologic alteration. Spatial variation in estimates revealed strongholds and high-risk areas relevant to conservation decision making. Projected change in probabilities of each risk category based on multiple land-use and climate models was generally small relative to high baseline risk resulting from past landscape changes. Assessing extinction risk based on probabilities of ordinal condition as a function of landscape patterns may provide a flexible and robust approach for many at-risk taxa by adjusting species' demographic criteria to match relative risk categories, following standardized criteria, or using expert elicitation for data-deficient species. This approach provides decision makers with a useful measure of uncertainty around ordinal classifications and provides a framework for estimating future risk based on projections of anthropogenic stressors.

Alabama, Georgia, Kentucky, North Carolina, South ↗

USGS1995

The value and vulnerability of small estuarine islands for conserving metapopulations of breeding waterbirds

Compelling arguments for preserving large habitat ‘islands’ have been made for a number of animal groups, but most commonly for terrestrial birds. We argue that, for many species of waterbirds nesting in coastal estuaries, maintaining numerous small islands may be a more effective management strategy than maintaining larger islands or reserves. In this study, the number of great white heron Ardea herodias nests over a 5-year period (1986–91) was negatively correlated with island area in the Florida Keys, USA. Nest densities were highest in the 2–10 ha island size range and lowest for islands larger than 100 ha. These small islands also attract nesting black skimmers Rynchops niger , brown pelicans Pelecanus occidentalis , and several species of terns and gulls. Small estuarine islands are vulnerable to sea level rise, erosion from watercraft, and, for dredge material islands, lack of sufficient maintenance because of competing needs for beach nourishment. Managers need to enforce more buffering and protection of these islands and argue for more dredged material allocations in some areas.

Florida↗

USGS2019

Managing the trifecta of disease, climate, and contaminants: Searching for robust choices under multiple sources of uncertainty

Wood frogs, like other amphibian species worldwide, are experiencing population declines due to multiple stressors. In the northeastern United States, wood frog declines are thought to result from a reduction in successful metamorphosis in part due to climate change, disease (specifically ranavirus) and contaminant exposure. The presence of multiple stressors can increase uncertainty in characterizing the main effects of each stressor, as well as understanding the degree to which their effects interact (additively or synergistically) to impact populations. This uncertainty adds inherent challenges to selecting appropriate management actions for conserving populations. Finding solutions that are robust to these uncertainties can improve management amid absent or equivocal knowledge. We used a Bayesian Belief Network (BBN), a quantitative tool that allowed us to evaluate how potential management actions might mitigate the effects of increasingly frequent and severe droughts, ranavirus exposure, and methylmercury on wood frog populations in the northeastern US. In our system, successful wood frog recruitment was largely driven by hydroperiod regardless of other stressors. Our modelling indicated that increased hydroperiod lowered the probability of complete metamorphosis failure from 0.6 to 0.37, suggesting that under the conditions tested in the model, pond hydrology, is more important for successful recruitment than either methylmercury or ranavirus exposure. As more information becomes available on stressor interactions, model scenarios could be re-run and management options re-evaluated.

Biological Conservation↗

USGS2023

Geographic and taxonomic variation in adaptive capacity among mountain-dwelling small mammals: implications for conservation status and actions

Contemporary climate change is modifying the distribution, morphology, phenology, physiology, evolution, and interspecific interactions of species. Effects of climate change are mediated not only through the magnitude of change experienced (exposure) and an animal's sensitivity to such changes, but also through the ability of the population or species to adjust to climatic variability and change genetically, behaviorally, or spatially (via its distribution) (i.e., adaptive capacity; AC). Here, we used an attribute-based framework to systematically evaluate and compare the AC of American pikas ( Ochotona princeps ) against four other mountain-dwelling small mammals of North America to determine whether pikas are disproportionately vulnerable to climate change, as has been postulated. Unlike previous analyses, we also compared AC across O. princeps lineages and across three taxonomic (and thus, spatial) scales. Our results indicate that pikas have markedly lower adaptive capacity than all compared species except bushy-tailed woodrats ( Neotoma cinerea ), and that our assessments of species generally align with earlier characterizations of climate-change vulnerability based on life-history characteristics. Although AC did not differ dramatically among pika lineages, some attributes are likely constraining AC differently in various parts of the geographic range. Comparisons across taxonomic levels of pikas illustrated that, although AC levels were comparable in pika lineages versus range-wide, AC was assessed as lower in interior-Great-Basin pikas than across the entire O.p. schisticeps lineage. We conclude that the comparatively lower AC of pikas results in particularly high susceptibility to anthropogenic climate change, corroborating results from numerous other recent investigations of pikas' climate-responsiveness. Adaptive-capacity evaluations appear useful as a consistent way to identify sentinel species or populations and for conservation prioritization.

Biological Conservation↗

USGS1991

Conservation of the yellow-shouldered blackbird Agelaius xanthomus, an endagered West Indian species

The yellow-shouldered blackbird Agelaius xanthomus , endemic to Puerto Rico and Mona Island, is endangered, mainly because of brood parasitism by the shiny cowbird Molothrus bonariensis , which reached Puerto Rico at least 30 years ago. The yellow-shouldered blackbird populations have since declined, about 770–1200 remaining (470–900 on Mona Island) by 1982–1986 compared to a population of about 2400 in 1975. Nearly all nests of blackbirds in most of its habitats are parasitized by cowbirds. This significantly reduces nesting success, but blackbirds have evolved no defenses against brood parasitism. Removal of cowbirds from the yellow-shouldered blackbird nesting grounds, modeled after similar programmes for the brown-headed cowbird Molothrus ater on Kirtland's warbler Dendroica kirtlandii nesting areas, significantly increased blackbird production. Blackbirds readily accept nest boxes, and breeding populations can be established in otherwise unusable sites and can be concentrated in mangrove habitats, were they are more easily protected by cowbird removal. Furthermore, yellow-shouldered blackbird pairs using cavities, including nest boxes, fledged more young per nest than pairs using open nests.

Boquerón Commonwealth Forest, Roosevelt Roads Nava↗

USGS2015

Home in the heat: Dramatic seasonal variation in home range of desert golden eagles informs management for renewable energy development

Renewable energy is expanding quickly with sometimes dramatic impacts to species and ecosystems. To understand the degree to which sensitive species may be impacted by renewable energy projects, it is informative to know how much space individuals use and how that space may overlap with planned development. We used global positioning system–global system for mobile communications (GPS-GSM) telemetry to measure year-round movements of golden eagles ( Aquila chrysaetos ) from the Mojave Desert of California, USA. We estimated monthly space use with adaptive local convex hulls to identify the temporal and spatial scales at which eagles may encounter renewable energy projects in the Desert Renewable Energy Conservation Plan area. Mean size of home ranges was lowest and least variable from November through January and greatest in February–March and May–August. These monthly home range patterns coincided with seasonal variation in breeding ecology, habitat associations, and temperature. The expanded home ranges in hot summer months included movements to cooler, prey-dense, mountainous areas characterized by forest, grasslands, and scrublands. Breeding-season home ranges (October–May) included more lowland semi-desert and rock vegetation. Overlap of eagle home ranges and focus areas for renewable energy development was greatest when eagle home ranges were smallest, during the breeding season. Golden eagles in the Mojave Desert used more space and a wider range of habitat types than expected and renewable energy projects could affect a larger section of the regional population than was previously thought.

California↗

USGS1992

Implications of morphological variation among populations of California roach Lavinia symmetricus (Cyprinidae) for conservation policy

The California roach Lavinia symmetricus is a small cyprinid native to Central California. Populations of roach are presently isolated from one another due to degradation of stream habitats between them. We examined eight populations, each from a tributary system of the San Joaquin River, to determine if morphological differences existed among them. These tributaries are now isolated from one another by dams or areas of unsuitable habitat. We found significant differences among drainages for all of the characters studied. Discriminant analysis classified 70% of the individuals to the correct drainage. The differences were not clinal because adjacent drainages were not grouped together in discriminant space. The most distinct population was as different from a nearby population (36 stream km) as from populations from other more distant tributaries and could possibly merit subspecies status. These results suggest that each population has been isolated long enough to develop morphological adaptions to local environment conditions. With one exception, the differences among the populations were too small for formal taxonomic recognition but suggest that management should focus on preserving local populations throughout the species' range, rather than scattered populations in a few reserves. This policy would serve to protect the genetic diversity of California roach, local aquatic habitats, and other even more poorly known species.

California↗

USGS2005

The potential conservation value of unmowed powerline strips for native bees

The land area covered by powerline easements in the United States exceeds the area of almost all national parks, including Yellowstone. In parts of Europe and the US, electric companies have altered their land management practices from periodic mowing to extraction of tall vegetation combined with the use of selective herbicides. To investigate whether this alternate management practice might produce higher quality habitat for native bees, we compared the bee fauna collected in unmowed powerline corridors and in nearby mowed grassy fields at the Patuxent Wildlife Research Center (MD). Powerline sites had more spatially and numerically rare species and a richer bee community than the grassy fields, although the difference was less pronounced than we expected. Powerline sites also had more parasitic species and more cavitynesting bees. Bee communities changed progressively through the season, but differences between the site types were persistent. The surrounding, nongrassland landscape likely has a strong influence on the bee species collected at the grassland sites, as some bees may be foraging in the grasslands but nesting elsewhere. Improving habitat for native bees will help ameliorate the loss of pollination services caused by the collapse of wild and managed honeybee populations. This study suggests that powerline strips have the potential to provide five million acres of bee-friendly habitat in the US if utilities more generally adopt appropriate management practices.

Biological Conservation↗

USGS2025

Coexistence beyond disciplinary silos: Five dimensions of analysis for more convivial human-predator interactions

Understanding human-predator interactions has been a central goal of conservation for decades, yet many previous efforts have approached this challenge from disciplinary perspectives focused on single case studies. There is a need for more transdisciplinary and multi-sited research to enrich our understandings of the complexity of human-nonhuman interactions and to design ways to make them more convivial. The multi-year CONVIVA “convivial conservation” research project addressed this gap, involving scholars from natural sciences, social sciences and humanities to promote coexistence, biodiversity and justice in conservation across four diverse case studies of apex predators: jaguars in Brazil, wolves in Finland, lions in Tanzania, and brown bears in California, United States. In this article, we set out two key contributions. First, we highlight how our project created iterative, dialogue-based reflections amongst different disciplines and perspectives to inform research questions, methods and units of analysis, fulfilling what we see as a key need in the literature. Second, we operationalise our collaboration beyond disciplinary silos into a novel framework of five interconnected dimensions of analysis, that characterise human-predator interactions, drawing on a range of lenses and including a series of guiding questions. We also showcase empirical material from our cases across wildlife, environment, interactions, institutions and justice dimensions. We present our approach, framework and findings with collective reflections and an invitation for adaptation and further research on their suitability to other contexts and species.

Biological Conservation↗