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USGS2025

Greater white-fronted goose habitat use in Louisiana provides water depth management insights

Numerous waterfowl species have altered their geographic distribution in recent decades. The greater white-fronted goose ( Anser albifrons ) has shifted its wintering distribution from coastal marshes in Texas and Louisiana, USA, to interior landscapes, creating challenges for conservation managers. Although the range shift has been primarily attributed to landscape-scale changes in rice production, effects of fine-scale habitat conditions on greater white-fronted goose habitat use are unknown. Thus, information on fine-scale environmental conditions could provide information to managers working to mitigate effects of the shift. We used global positioning system neck collars to monitor 78 greater white-fronted geese in Louisiana each winter during 2016–2019 and visited all used locations to record vegetation height, water depth, and land cover. We modeled greater white-fronted goose habitat use in 4 regions across Louisiana (central, coastal, north, southwest), and evaluated effects of vegetation height, water depth, land cover, and interactions. In our candidate model set, we included a sampling null, which accounted for differences in sampling frequencies among hunt seasons and diel periods. The top model in the central, coastal, and north regions included water depth, whereas the top model in the southwest region included water depth, vegetation height, and land cover. Parameter estimates and confidence intervals indicated that goose habitat use was higher at sites with >5.1 cm of water compared to dry sites or sites with <5.1 cm of water. In the southwest region, goose habitat use was highest in areas identified as other land cover (e.g., corn, cotton, rye, sugarcane) and lowest in open water. Although Louisiana has substantial anthropogenic food resources in the form of rice agriculture and abundant grazing opportunities afforded by mild winters, our results indicate that wet areas provide better habitat to greater white-fronted geese than dry areas. New agricultural flooding regimes in Louisiana could improve habitat quality and potentially mitigate some effects of the winter distribution shift.

Louisiana↗

USGS2016

Movement and survival of an amphibian in relation to sediment and culvert design

Habitat disturbance from stream culverts can affect aquatic organisms by increasing sedimentation or forming barriers to movement. Land managers are replacing many culverts to reduce these negative effects, primarily for stream fishes. However, these management actions are likely to have broad implications for many organisms, including amphibians in small streams. To assess the effects of culverts on movement and survival of the Idaho giant salamander ( Dicamptodon aterrimus ), we used capture-mark-recapture surveys and measured sediment in streams with 2 culvert types (i.e., unimproved culverts, improved culverts) and in streams without culverts (i.e., reference streams). We predicted culverts would increase stream sediment levels, limit movement, and reduce survival of Idaho giant salamanders. We also determined the effect of sediment levels on survival of salamanders because although sediment is often associated with distribution and abundance of stream amphibians, links with vital rates remain unclear. To estimate survival, we used a spatial Cormack–Jolly–Seber (CJS) model that explicitly incorporated information on movement, eliminating bias in apparent survival estimated from traditional (i.e., non-spatial) CJS models caused by permanent emigration beyond the study area. To demonstrate the importance of using spatial data in studies of wildlife populations, we compared estimates from the spatial CJS to estimates of apparent survival from a traditional CJS model. Although high levels of sediment reduced survival of salamanders, culvert type was unrelated to sediment levels or true survival of salamanders. Across all streams, we documented only 15 movement events between study reaches. All movement events were downstream, and they occurred disproportionately in 1 stream, which precluded measuring the effect of culvert design on movement. Although movement was low overall, the variance among streams was high enough to bias estimates of apparent survival compared to true survival. Our results suggest that where sedimentation occurs from roads and culverts, survival of the Idaho giant salamander could be reduced. Though culverts clearly do not completely block downstream movements of Idaho giant salamanders, the degree to which culvert improvements affect movements under roads in comparison to unimproved culverts remains unclear, especially for rare, but potentially important, upstream movements.

Idaho, Montana↗

USGS2016

Effects of lek count protocols on greater sage-grouse population trend estimates

Annual counts of males displaying at lek sites are an important tool for monitoring greater sage-grouse populations ( Centrocercus urophasianus ), but seasonal and diurnal variation in lek attendance may increase variance and bias of trend analyses. Recommendations for protocols to reduce observation error have called for restricting lek counts to within 30 minutes of sunrise, but this may limit the number of lek counts available for analysis, particularly from years before monitoring was widely standardized. Reducing the temporal window for conducting lek counts also may constrain the ability of agencies to monitor leks efficiently. We used lek count data collected across Wyoming during 1995−2014 to investigate the effect of lek counts conducted between 30 minutes before and 30, 60, or 90 minutes after sunrise on population trend estimates. We also evaluated trends across scales relevant to management, including statewide, within Working Group Areas and Core Areas, and for individual leks. To further evaluate accuracy and precision of trend estimates from lek count protocols, we used simulations based on a lek attendance model and compared simulated and estimated values of annual rate of change in population size (λ) from scenarios of varying numbers of leks, lek count timing, and count frequency (counts/lek/year). We found that restricting analyses to counts conducted within 30 minutes of sunrise generally did not improve precision of population trend estimates, although differences among timings increased as the number of leks and count frequency decreased. Lek attendance declined >30 minutes after sunrise, but simulations indicated that including lek counts conducted up to 90 minutes after sunrise can increase the number of leks monitored compared to trend estimates based on counts conducted within 30 minutes of sunrise. This increase in leks monitored resulted in greater precision of estimates without reducing accuracy. Increasing count frequency also improved precision. These results suggest that the current distribution of count timings available in lek count databases such as that of Wyoming (conducted up to 90 minutes after sunrise) can be used to estimate sage-grouse population trends without reducing precision or accuracy relative to trends from counts conducted within 30 minutes of sunrise. However, only 10% of all Wyoming counts in our sample (1995−2014) were conducted 61−90 minutes after sunrise, and further increasing this percentage may still bias trend estimates because of declining lek attendance.

Journal of Wildlife Management↗

USGS2010

Spatial models of Northern Bobwhite populations for conservation planning

Since 1980, northern bobwhite (Colinus virginianus) range-wide populations declined 3.9% annually. Within the West Gulf Coastal Plain Bird Conservation Region in the south-central United States, populations of this quail species have declined 6.8% annually. These declines sparked calls for land use change and prompted implementation of various conservation practices. However, to effectively reverse these declines and restore northern bobwhite to their former population levels, habitat conservation and management efforts must target establishment and maintenance of sustainable populations. To provide guidance for conservation and restoration of habitat capable of supporting sustainable northern bobwhite populations in the West Gulf Coastal Plain, we modeled their spatial distribution using landscape characteristics derived from 1992 National Land Cover Data and bird detections, from 1990 to 1994, along 10-stop Breeding Bird Survey route segments. Four landscape metrics influenced detections of northern bobwhite: detections were greater in areas with more grassland and increased aggregation of agricultural lands, but detections were reduced in areas with increased density of land cover edge and grassland edge. Using these landscape metrics, we projected the abundance and spatial distribution of northern bobwhite populations across the entire West Gulf Coastal Plain. Predicted populations closely approximated abundance estimates from a different cadre of concurrently collected data but model predictions did not accurately reflect bobwhite detections along species-specific call-count routes in Arkansas and Louisiana. Using similar methods, we also projected northern bobwhite population distribution circa 1980 based on Land Use Land Cover data and bird survey data from 1976 to 1984. We compared our 1980 spatial projections with our spatial estimate of 1992 populations to identify areas of population change. Additionally, we used our projection of the spatial distribution and abundance of bobwhite to predict areas of population sustainability. Our projections of population change and sustainability provide guidance for targeting habitat conservation and rehabilitation efforts for restoration of northern bobwhite populations in the West Gulf Coastal Plain.

Journal of Wildlife Management↗

USGS2025

Movements and habitat use vary across the Rocky Mountain Population of trumpeter swans

The Rocky Mountain Population (RMP) of trumpeter swans Cygnus buccinator (hereafter, swans) in North America includes breeders in the Greater Yellowstone Area (GYA) and other western states (together, United States segment) and western provinces of Canada (Canada segment). Conservation concern for the United States segment stems from its slow population growth and the resident nature of GYA swans, which intermingle with migrating Canada segment swans in wintering habitats. Thus, understanding variation in migratory behavior and habitat use by swans in the two population segments can inform how management actions may affect the RMP. We used telemetry data from 55 RMP swans captured in the western United States to understand their movements and habitat use. For 45 swans (60 swan-years) that spent the summer in the United States, distance traveled between breeding and wintering areas ranged from 0 km (i.e., no migration in 22% of swan-years) to 473 km, with an average of nonzero movements of 118 ± 95 km (SD). Swans traveled farther distances when maximum temperatures were lower. For 10 swans (16 swan-years) that spent the summer in Canada, five appeared to molt but not to nest, and four appeared to nest in one or more years. Migration timing was similar for molting and nesting swans. All five molting swans and one nesting swan spent at least one previous summer in the GYA. Migratory connectivity of all birds was weaker in years when more swans migrated to Canada for the summer. During the breeding season, Canada swans used low-elevation lakes, but United States swans used high-elevation lakes. Both groups of swans increased use of crop fields outside of the breeding season. Our study shows interchange between the United States and Canada segments, a finding that challenges the efficacy of existing population designations. Furthermore, variation in movement behavior of GYA swans suggests possible actions, such as restoring winter habitats to increase swan distribution and migration, to support swan conservation.

Rocky Mountains↗

USGS1993

Survival of northern pintails banded during winter in North America, 1950-88

From 1950 through 1988, the continental breeding population of northern pintails ( Anas acuta ) varied from 2.0 million to 9.9 million. Because pintails have high fidelity to certain wintering grounds along coasts and large bodies of water, management on these wintering areas may increase population size if changes in winter survival rate are related to changes in population size. I used band-recovery data to estimate survival rates for winter-banded pintails and to test for sex-specific, temporal, and geographic variation in survival rates. Survival rate estimates varied between 0.632 and 0.806 for males, and 0.421 and 0.769 for females. Males had higher ( P < 0.0001) average annual survival rates than females. Limited geographic variation occurred in estimates of average annual survival rates for males, and no variation occurred for females. Males had lower average annual survival rates in the Imperial Valley than in central California ( P = 0.007) or in the Gulf Coast ( P = 0.092). Little annual variation was found within time periods. However, longer-term variation was found in survival rate estimates for males and females. Males had higher ( P = 0.054) average annual survival rates in the Pacific Flyway during 1959-61, a period of drought, breeding-population decline, and restrictive hunting regulations, than during 1950-58, a period with a higher breeding population and liberal regulations. The increase in wintering population size in the Pacific Flyway during the 1970's was associated with a higher average annual survival rate for females in the Pacific Flyway than during the 1950's. Results from the Pacific Flyway suggested that an interaction may exist between population size and the effect of harvest regulations on survival of males. Changes in harvest regulations appeared to have a greater effect at lower population levels.

North America↗

USGS2011

Detection probability in aerial surveys of feral horses

Observation bias pervades data collected during aerial surveys of large animals, and although some sources can be mitigated with informed planning, others must be addressed using valid sampling techniques that carefully model detection probability. Nonetheless, aerial surveys are frequently employed to count large mammals without applying such methods to account for heterogeneity in visibility of animal groups on the landscape. This often leaves managers and interest groups at odds over decisions that are not adequately informed. I analyzed detection of feral horse (Equus caballus) groups by dual independent observers from 24 fixed-wing and 16 helicopter flights using mixed-effect logistic regression models to investigate potential sources of observation bias. I accounted for observer skill, population location, and aircraft type in the model structure and analyzed the effects of group size, sun effect (position related to observer), vegetation type, topography, cloud cover, percent snow cover, and observer fatigue on detection of horse groups. The most important model-averaged effects for both fixed-wing and helicopter surveys included group size (fixed-wing: odds ratio = 0.891, 95% CI = 0.850–0.935; helicopter: odds ratio = 0.640, 95% CI = 0.587–0.698) and sun effect (fixed-wing: odds ratio = 0.632, 95% CI = 0.350–1.141; helicopter: odds ratio = 0.194, 95% CI = 0.080–0.470). Observer fatigue was also an important effect in the best model for helicopter surveys, with detection probability declining after 3 hr of survey time (odds ratio = 0.278, 95% CI = 0.144–0.537). Biases arising from sun effect and observer fatigue can be mitigated by pre-flight survey design. Other sources of bias, such as those arising from group size, topography, and vegetation can only be addressed by employing valid sampling techniques such as double sampling, mark–resight (batch-marked animals), mark–recapture (uniquely marked and identifiable animals), sightability bias correction models, and line transect distance sampling; however, some of these techniques may still only partially correct for negative observation biases.

Journal of Wildlife Management↗

USGS2011

The importance of within-year repeated counts and the influence of scale on long-term monitoring of sage-grouse

Long‐term population monitoring is the cornerstone of animal conservation and management. The accuracy and precision of models developed using monitoring data can be influenced by the protocols guiding data collection. The greater sage‐grouse ( Centrocercus urophasianus ) is a species of concern that has been monitored over decades, primarily, by counting the number of males that attend lek (breeding) sites. These lek count data have been used to assess long‐term population trends and for multiple mechanistic studies. However, some studies have questioned the efficacy of lek counts to accurately identify population trends. In response, monitoring protocols were changed to have a goal of counting lek sites multiple times within a season. We assessed the influence of this change in monitoring protocols on model accuracy and precision applying generalized additive models to describe trends over time. We found that at large spatial scales including >50 leks, the absence of repeated counts within a year did not significantly alter population trend estimates or interpretation. Increasing sample size decreased the model confidence intervals. We developed a population trend model for Wyoming greater sage‐grouse from 1965 to 2008, identifying significant changes in the population indices and capturing the cyclic nature of this species. Most sage‐grouse declines in Wyoming occurred between 1965 and the 1990s and lek count numbers generally increased from the mid‐1990s to 2008. Our results validate the combination of monitoring data collected under different protocols in past and future studies—provided those studies are addressing large‐scale questions. We suggest that a larger sample of individual leks is preferable to multiple counts of a smaller sample of leks.

Wyoming↗

USGS2017

Greater sage-grouse population trends across Wyoming

The scale at which analyses are performed can have an effect on model results and often one scale does not accurately describe the ecological phenomena of interest (e.g., population trends) for wide-ranging species: yet, most ecological studies are performed at a single, arbitrary scale. To best determine local and regional trends for greater sage-grouse ( Centrocercus urophasianus ) in Wyoming, USA, we modeled density-independent and -dependent population growth across multiple spatial scales relevant to management and conservation (Core Areas [habitat encompassing approximately 83% of the sage-grouse population on ∼24% of surface area in Wyoming], local Working Groups [7 regional areas for which groups of local experts are tasked with implementing Wyoming's statewide sage-grouse conservation plan at the local level], Core Area status (Core Area vs. Non-Core Area) by Working Groups, and Core Areas by Working Groups). Our goal was to determine the influence of fine-scale population trends (Core Areas) on larger-scale populations (Working Group Areas). We modeled the natural log of change in population size ( peak M lek counts) by time to calculate the finite rate of population growth ( λ ) for each population of interest from 1993 to 2015. We found that in general when Core Area status (Core Area vs. Non-Core Area) was investigated by Working Group Area, the 2 populations trended similarly and agreed with the overall trend of the Working Group Area. However, at the finer scale where Core Areas were analyzed separately, Core Areas within the same Working Group Area often trended differently and a few large Core Areas could influence the overall Working Group Area trend and mask trends occurring in smaller Core Areas. Relatively close fine-scale populations of sage-grouse can trend differently, indicating that large-scale trends may not accurately depict what is occurring across the landscape (e.g., local effects of gas and oil fields may be masked by increasing larger populations).

Wyoming↗

USGS2006

Patch size and landscape effects on density and nesting success of grassland birds

Current management recommendations for grassland birds in North America emphasize providing large patches of grassland habitat within landscapes that have few forest or shrubland areas. These Bird Conservation Areas are being proposed under the assumption that large patches of habitat in treeless landscapes will maintain viable populations of grassland birds. This assumption requires that patch size and landscape features affect density and nesting success of grassland birds, and that these effects are consistent among years and regions and across focal species. However, these assumptions have not yet been validated for grassland birds, and the relative importance of local vegetation structure, patch size, and landscape composition on grassland bird populations is not well known. In addition, factors influencing grassland bird nesting success have been investigated mostly in small-scale and short-duration studies. To develop management guidelines for grassland birds, we tested the spatial and temporal repeatability of the influence of patch size and landscape composition on density and nesting success of 3 grassland passerines, after controlling for local-scale vegetation structure, climate, and—when analyzing nest success—bird density. We conducted our study during 4 years (1998–2001) in 44 study plots that were set up in 3 regions of the northern tallgrass prairie in Minnesota and North Dakota, USA. In these study plots we measured density and nesting success of clay-colored sparrows ( Spizella pallida ), Savannah sparrows ( Passerculus sandwichensis ), and bobolinks ( Dolichonyx oryzivorus ). Statistical models indicated that density was influenced by patch size, landscape, region, and local vegetation structure more so than by local vegetation structure alone. Both magnitude and direction of the response of density to patch size varied among regions, years, and species. In contrast, the direction of landscape effects was consistent among regions, years, and between Savannah sparrows and bobolinks. In each species, this landscape effect was independent of patch size. Nesting success was not clearly influenced by patch size or landscape composition, and none of the factors that influenced avian density also influenced nesting success in any of the 3 species. General statements on “optimal habitat” for grassland birds should therefore be viewed cautiously. Instead, long-term studies in different regions as well as a deeper understanding of the local system are needed to determine which factors are most important for grassland birds in a particular area.

Journal of Wildlife Management↗

USGS2025

Greater sage-grouse seasonal habitat associations: A review and considerations for interpretation and management applications

Habitat features needed by wildlife can change in composition throughout the year, particularly in temperate ecosystems, leading to distinct seasonal spatial-use patterns. Studies of species-habitat associations therefore often focus on understanding relationships within discrete seasonal periods with common goals of prediction (e.g., habitat mapping) and inference (e.g., interpreting model coefficients). Across the range of the greater sage-grouse ( Centrocercus urophasianus ) of western North America, the increasing use of high-frequency tracking devices has led to a surge in habitat association studies covering multiple temporal periods and spatial extents. We reviewed the literature for seasonal habitat association studies corresponding to the second and third orders of selection (Johnson 1980). Our objectives were to summarize the methodological approaches used to estimate habitat associations to aid understanding in cross-study comparisons and identify common habitat features reported as selected or avoided within different seasonal periods. We reviewed 71 second- and third-order studies published from 2007–2023 that evaluated covariates collected in a geographic information system (GIS) and modeled probability of selection or intensity of use. The most common study design evaluated a single level of selection (third-order) and was multi-scale (i.e., covariates were measured at varying spatial grains). The most common model approach estimated habitat associations using resource selection functions (RSFs) fit with logistic regression. Studies mostly focused on the breeding periods and winter, but all seasons throughout the annual cycle were covered. There was clear support for selection of sagebrush and avoidance of trees and rugged terrain across seasons, and strong selection of mesic conditions in summer. However, habitat associations for most covariates were mixed, with proportionally equivalent selection and avoidance reported, even within the same seasons. Different factors hampered cross-study comparisons, including variation in study design, but additional contributors likely included important context-dependent habitat associations, such as functional responses to changing habitat availability. We suggest collaborative studies leveraging multiple datasets can help improve seasonal habitat inference by removing the effects of variable study designs.

Journal of Wildlife Management↗

USGS2000

Evaluating immunocontraception for managing suburban white-tailed deer in Irondequoit, New York

Immunocontraception is frequently proposed as an alternative to lethal removal of females for deer management. However, little information is available for evaluating the potential of applying immunocontraceptives to free-ranging populations. Our objectives were to estimate effort required to apply porcine zona pellucida (PZP) to individual deer and assess the utility of using immunocontraception to control growth of deer populations. The study was conducted in a 43-km2 suburban community with about 400 deer. Effort per deer was measured as time required to capture and mark deer, and then to apply booster immunocontraceptive treatments by remote injection. Estimates of numbers of females to treat to control population growth were based on the generalized sustained-yield (SY) model adapted for contraception of females. The SY curve was calibrated using data on deer abundance acquired from aerial population surveys and nutritional condition of females removed by a concurrent culling program. Effort was influenced by 4 factors: deer population density, approachability of individual deer, access to private and public land, and efficacy of the contraceptive treatment. Effort and deer density were inversely related. Cumulative effort for treatment increased exponentially because some deer were more difficult to approach than others. Potential of using immunocontraception at low deer population densities (<25% ecological carrying capacity) is limited by the interaction of the proportion of breeding-age females in the population and treatment efficacy, as well as encounter rates. Immunocontraception has the best potential for holding suburban deer populations between 30 and 70% of ecological carrying capacity, but is likely to be useful only in localized populations when the number of females to be treated is small (e.g., <200 deer).

New York↗

USGS1994

Seasonal and annual survival of emperor geese

Population levels of emperor geese ( Chen canagica ) in Alaska in 1993 were about half that estimated in the 1960s. Survival information is necessary for managers to decide how to best enhance recovery of this species to former levels. We calculated seasonal and annual estimates of emperor goose survival from resightings of neck-collared birds. Geese were neck collared in 1988-90 on their breeding grounds in the Yukon-Kuskokwim Delta, Alaska, and resighted each spring and fall, 1988-92, at staging areas on the Alaska Peninsula. Adult monthly survival rates during overwinter periods (1 Oct-30 Apr) were not different (P = 0.281) among years ( Ŝ' = 0.940, SE = 0.009), whereas monthly rates of oversummer (1 May-30 Sep) survival showed annual variation (P = 0.048). However, we constrained oversummer survival to a single estimate of 0.980 (0.010). Monthly survival estimates for juveniles during their first overwinter period did not vary among years (P = 0.999) and was 0.710 (0.018). Subsequent monthly survival for juveniles was 0.943 (0.010), similar to that for adults. We developed an adjustment procedure to account for philopatric behavior of geese and this enabled us to use data for postbanding (1 Aug-30 Sep) periods. Survival estimates were low compared with those for other goose species, particularly for juveniles. We addressed collar loss and heterogeneity in resighting probabilities and felt their contribution to potential model bias was insignificant. Annual survival among adults (Ŝ' = 0.631, SE = 0.023) was not different (P = 0.709) from that observed during 1982-85 (Petersen 1992). The similarity in survival rates in these studies suggests that harvest regimes did not differ between the 2 periods. This suggests that continued subsistence harvest has contributed to persistent low population levels in emperor geese.

Alaska↗

USGS2022

Integrating distance sampling survey data with population indices to separate trends in abundance and temporary immigration

Managers rely on accurate estimators of wildlife abundance and trends for management decisions. Despite the focus of contemporary wildlife science on developing methods to improve inference from wildlife surveys, legacy datasets often rely on index counts that lack information about the detection process. Data integration can be a useful tool for combining index counts with data collected under more rigorous designs (i.e., designs that account for the detection process), but care is required when datasets represent different population processes or are mismatched in space and time. This can be particularly problematic in cases where animals aggregate in response to a spatially or temporally limited resource because individuals may temporarily immigrate from outside the study area and be included in the abundance index. Abundance indices based on brown bear ( Ursus arctos ) feeding aggregations within coastal meadows in early summer in Lake Clark National Park and Preserve, Alaska, USA, are one such example. These indices reflect the target population (brown bears residing within the park) and temporary immigrants (i.e., bears drawn from outside the park boundary). To properly account for the effects of temporary immigration, we integrated the index data with abundance data collected via park-wide distance sampling surveys, the latter of which properly addressed the detection process. By assuming that the distance data provide inference on abundance and the index counts represent some combination of abundance and temporary immigration processes, we were able to decompose the relative contribution of each to overall trend. We estimated that the density of brown bears within our study area was 38–54 adults/1,000 km 2 during 2003–2019 and that abundance increased at a rate of approximately 1.4%/year. The contribution of temporary immigrants to overall trend in the index was low, so we created 3 hypothetical scenarios to more fully demonstrate how the integrated approach could be useful in situations where the composite trend in meadow counts may obscure trends in abundance (e.g., opposing trends in abundance and temporary immigration). Our work represents a conceptual advance supporting the integration of legacy index data with more rigorous data streams and is broadly applicable in cases where trends in index values may represent a mixture of population processes.

Alaska↗

USGS2005

Population genetics of Gunnison sage-grouse: Implications for management

The newly described Gunnison sage-grouse ( Centrocercus minimus ) is a species of concern for management because of marked declines in distribution and abundance due to the loss and fragmentation of sagebrush habitat. This has caused remaining populations to be unusually small and isolated. We utilized mitochondrial DNA sequence data and data from 8 nuclear microsatellites to assess the extent of population subdivision among Gunnison sage-grouse populations in southwestern Colorado and southeastern Utah, USA. We found a high degree of population structure and low amounts of gene flow among all pairs of populations except the geographically adjacent Gunnison and Curecanti populations. Population structure for Gunnison sage-grouse was significantly higher than has been reported for greater sage-grouse ( C. urophasianus ). Further, we documented low levels of genetic diversity in some populations (particularly Dove Creek/Monticello and Piñon Mesa with an average of only 3.00 and 2.13 alleles per locus respectively) indicating that translocations from larger, more genetically diverse populations may be warranted. Bayesian analysis identified 3 potential migrants (involving San Miguel, Dove Creek/Monticello, Crawford, and Curecanti). Further, this analysis showed that 4 individuals from Cerro/Cimarron were more closely related to birds from San Miguel than to its geographically closer neighbors Gunnison and Curecanti. This suggests the Cerro/Cimarron area may act as a stepping stone for gene flow between San Miguel and Gunnison and that habitat restoration and protection in areas between these 2 basins should be a priority in an attempt to facilitate natural movement among these populations. Conservation plans should include monitoring and maintaining genetic diversity, preventing future habitat loss and fragmentation, enhancing existing habitat, and restoring converted sagebrush communities.

Journal of Wildlife Management↗

USGS2010

A sightability model for mountain goats

Unbiased estimates of mountain goat (Oreamnos americanus) populations are key to meeting diverse harvest management and conservation objectives. We developed logistic regression models of factors influencing sightability of mountain goat groups during helicopter surveys throughout the Cascades and Olympic Ranges in western Washington during summers, 20042007. We conducted 205 trials of the ability of aerial survey crews to detect groups of mountain goats whose presence was known based on simultaneous direct observation from the ground (n 84), Global Positioning System (GPS) telemetry (n 115), or both (n 6). Aerial survey crews detected 77 and 79 of all groups known to be present based on ground observers and GPS collars, respectively. The best models indicated that sightability of mountain goat groups was a function of the number of mountain goats in a group, presence of terrain obstruction, and extent of overstory vegetation. Aerial counts of mountain goats within groups did not differ greatly from known group sizes, indicating that under-counting bias within detected groups of mountain goats was small. We applied HorvitzThompson-like sightability adjustments to 1,139 groups of mountain goats observed in the Cascade and Olympic ranges, Washington, USA, from 2004 to 2007. Estimated mean sightability of individual animals was 85 but ranged 0.750.91 in areas with low and high sightability, respectively. Simulations of mountain goat surveys indicated that precision of population estimates adjusted for sightability biases increased with population size and number of replicate surveys, providing general guidance for the design of future surveys. Because survey conditions, group sizes, and habitat occupied by goats vary among surveys, we recommend using sightability correction methods to decrease bias in population estimates from aerial surveys of mountain goats.

Journal of Wildlife Management↗

USGS2020

Black bear movement and food conditioning in an exurban landscape

Conflicts between humans and wildlife have become increasingly important challenges for resource managers along the urban‐wildland interface. Food conditioning (i.e., reliance by an animal on anthropogenic foods) of American black bears (Ursus americanus ) is related to conflict behavior (i.e., being bold or aggressive toward humans, consuming human food or garbage, causing property damage) and often occurs in communities adjacent to Great Smoky Mountains National Park (GRSM or Park), USA. The goal of our study was to evaluate black bear space use in GRSM and in exurban areas on surrounding private lands and to identify factors associated with food conditioning and conflict behavior. We radio‐collared 53 bears (29 males, 24 females) from 2015 to 2017 to compare space use characteristics and used carbon isotopic signatures (δ13C) from bear hair to assess food conditioning. We then performed an integrated step selection function (iSSF) analysis to characterize and compare movement and resource use as related to food conditioning. Based on the stable isotope analyses, 24 bears were classified as food conditioned (FC; 16 males and 8 females) and 37 were not food conditioned (NFC; 14 males and 23 females). Annual 95% kernel density estimate (KDE) home ranges and 50% KDE core area estimates of female and male bears did not differ by level of food conditioning (i.e., mean δ13C), but 95% and 50% home ranges of FC females were smaller than NFC females when data from 2015, a year of food scarcity and abnormally large home ranges, were excluded. The mean proportion of exurban development (e.g., roads, buildings, openings) within 95% KDE and 50% KDE home ranges of females increased with mean δ13C (i.e., greater food conditioning). The iSSF models indicated that FC bears were more likely to use forest openings associated with higher levels of development than NFC bears. We used those models to demonstrate how landscape modifications can reduce bear use of exurban areas, particularly for NFC bears. Our stable isotope, movement, and resource use data indicate that conflict behaviors displayed by many bears within GRSM were learned in areas outside Park boundaries. © 2020 The Wildlife Society.

Tennessee, North Carolina↗

USGS2015

Camera traps and mark-resight models: The value of ancillary data for evaluating assumptions

Unbiased estimators of abundance and density are fundamental to the study of animal ecology and critical for making sound management decisions. Capture–recapture models are generally considered the most robust approach for estimating these parameters but rely on a number of assumptions that are often violated but rarely validated. Mark-resight models, a form of capture–recapture, are well suited for use with noninvasive sampling methods and allow for a number of assumptions to be relaxed. We used ancillary data from continuous video and radio telemetry to evaluate the assumptions of mark-resight models for abundance estimation on a barrier island raccoon (Procyon lotor) population using camera traps. Our island study site was geographically closed, allowing us to estimate real survival and in situ recruitment in addition to population size. We found several sources of bias due to heterogeneity of capture probabilities in our study, including camera placement, animal movement, island physiography, and animal behavior. Almost all sources of heterogeneity could be accounted for using the sophisticated mark-resight models developed by McClintock et al. (2009b) and this model generated estimates similar to a spatially explicit mark-resight model previously developed for this population during our study. Spatially explicit capture–recapture models have become an important tool in ecology and confer a number of advantages; however, non-spatial models that account for inherent individual heterogeneity may perform nearly as well, especially where immigration and emigration are limited. Non-spatial models are computationally less demanding, do not make implicit assumptions related to the isotropy of home ranges, and can provide insights with respect to the biological traits of the local population.

North Carolina↗