Timing of grizzly bear (Ursus arctos) parturition during hibernation has been explained by ancestral traits (delayed implantation, altricial young, obligate maternal denning), but the ultimate driver underlying precise timing has not been fully explored. Capitalizing on an observed latitudinal increase in denning duration among four populations in interior North America, we tested two alternative hypotheses. First, that birth timing results from a physiological cue that synchronizes implantation with the onset of hibernation, allowing females to forgo reproduction should they lack adequate fat stores. Alternatively, that parturition is optimally timed relative to den exit to balance an energetic tradeoff between minimizing lactation time to protect the mother and maximizing developmental time to increase cub survival. Using parturition dates previously predicted from accelerometer data (27 Dec-28 Feb), we classified 115 females according to apparent litter survival when first visually observed after den exit: 57% successful (with cubs), 22% unsuccessful (alone), and 21% unknown (not observed). The number of days between birth and den exit showed no association with latitude (p = 0.29). It averaged 103 days among successful females but only 77 days among unsuccessful females (p < 0.001) owing to later births and earlier exit. With each increasing degree of latitude, birth date increased by 1.0 and number of days between den entry and birth increased by 2.5 (p < 0.001). Implantation dates were not centered on den entry dates (p < 0.001). These results supported the energetic tradeoff hypothesis and suggested natural selection has favored a consistent number of days between parturition and den exit under average body conditions and shifts toward later or earlier births for females with lower or higher levels of bodily stored energy, respectively. This flexible tradeoff may support resilience to climate change and present a possible mechanism explaining reduced natality and cub survival in high-density populations.

Huckleberries (Vaccinium spp.) are a nutritionally important food to grizzly bears (Ursus arctos) in interior, western North America. They provide sugar-rich calories in late summer and fall prior to denning. We developed a resource selection function of high-quality huckleberry habitat important to Cabinet-Yaak and Selkirk female grizzly bears using field-verified huckleberry foraging radiolocations acquired during prime months of huckleberry fruiting (July 15-September 15, 2010-2019, n = 22). Logistic regression analysis identified a model with 12 significant variables in predicting huckleberry habitat important to female grizzly bears (Somers' D = 0.729; K-S statistic = 0.570, p < 0.00001). Most influential variables (p < 0.00001; positive [+] or negative [-] relationship) include canopy closure (-), moisture deficit (-), time since last wildfire (-), solar radiation (+), snow water equivalent (-), and growing degree days above 5°C (-). On average, 28% of an adult female annual home range includes predicted huckleberry habitat ( x ¯ = 61 ± 6.4 [SE] square kilometers). Seasonal ranges of females overlap extensively within predicted huckleberry habitat, and degree of overlap trends with quality of habitat. Mothers and daughters display similar selection patterns for predicted huckleberry habitat, suggesting huckleberries are an important component of dispersal patterns, range expansion, and connectivity (via linkage areas) to other populations. Model values were significantly associated with long-term berry production, allowing estimates of amount of this food resource available on the landscape. Using energetic predictions of huckleberry foraging in these areas, we find that a smaller average body size of Cabinet-Yaak and Selkirk adult females ( x ¯ = 94 kg lean body mass) lessens the energetic constraints of a huckleberry-dominant diet and may be a direct outcome of huckleberries being a primary food resource for these populations.

Per- and polyfluoroalkyl substances (PFAS) and pesticides are globally distributed contaminants that persist in terrestrial food webs, yet baseline data for large omnivores in the continental U.S. remain limited. This study quantified PFAS and pesticides in whole blood from free-ranging black bears (Ursus americanus, n = 15) and grizzly bears (Ursus arctos horribilis, n = 9) in the Cabinet-Yaak Ecosystem of northwestern Montana. Using high-resolution mass spectrometry-based methods (GC-MS/MS and LC-MS/MS), 52 PFAS and 186 pesticides were analyzed. PFAS were detected in all bears, with total PFAS concentrations ranging from 79.5 to 317 pg/mL. PFAS profiles were dominated by long-chain perfluoroalkyl carboxylic acids, particularly PFOA, PFDA, and PFUnDA, with minimal contribution from short-chain compounds. Species was the strongest ecological predictor of PFAS concentrations, although variability across age, sex, and capture location were observed. Only two pesticides, piperonyl butoxide and permethrin, were detected at quantifiable concentrations (2070-12,600 pg/mL), and no correlations were observed between pesticide and PFAS concentrations, indicating independent exposure pathways. The predominance of long-chain PFAS suggests diffuse environmental sources and bioaccumulation within terrestrial food webs. Although measured concentrations were generally low relative to other wildlife toxicological studies, the persistence and protein-binding properties of long-chain PFAS warrant continued monitoring, particularly for long-lived omnivores. These results establish baseline contaminant concentrations for two apex omnivores in a remote ecosystem and highlight the utility of large mammals as integrative sentinels of environmental contaminant exposure for regional monitoring and wildlife conservation. Continued monitoring in the Cabinet-Yaak and across western North America will be critical for assessing temporal trends, identifying new contaminant sources, and evaluating ecological health in bear populations.

Small, isolated wildlife populations are often at great conservation risk. Quantitative monitoring of their conservation status over time and evidence of recovery is relatively rare. We carried out population surveys of grizzly bears (Ursus arctos) pre- (2005) and post- (2020-2021) conservation management, to assess the efficacy of strategic measures applied to the at-risk Canadian South Selkirk grizzly bear population in southeastern British Columbia. We evaluated our management outcomes by comparing our recent survey results with recovery targets outlined in a 2016 Recovery Management Plan, which included abundance, trend, number and distribution of females, distribution of reproductive females, mortality rates, and inter-population connectivity. Surveys consisted of remote genetic sampling where DNA from hair roots generated genotypes identifying individuals, sex, and family units. In 2020-2021, we identified 73 individuals (41 females, 32 males) that were used in a spatially explicit capture-recapture (SECR) density estimate, and 8 individuals sampled opportunistically at rub sites that were used in our connectivity analysis. We estimated the average number of bears using the area at any one time to be 69 (95% CI = 56-86). This estimate exceeded our closure-corrected recovery target of 60 bears. Densities were highest in the northern and central portions of the area, but the average density was estimated to be 17 grizzly bears/1,000 km2 (95% CI = 14-22). Female distribution and evidence of reproduction varied spatially but occurred in all 6 delineated subunits, which exceeded our target of occurring in 5 subunits. Human-caused female mortality reported over the past 6 years was 0.5 bears/year, well below our target of 1 bear/year. We identified 9 immigrants (1F, 8M) from the Purcell Mountains who bred 27 offspring (12F, 15M) with other South Selkirk mates. This level of connectivity and gene flow represented a substantial increase for this previously fragmented population. Our results suggest that 15 years of conservation management have significantly improved the status of the Canadian South Selkirk grizzly bear population.

Genetic monitoring is important in small, fragmented populations that rely on gene flow to maintain genetic diversity. The Selkirk, Yaak, and Cabinet grizzly bear (Ursus arctos) populations are among the smallest in North America and are near the southernmost extent of the species’ range. These populations received little to no effective migration for generations but have recently experienced increased gene flow through natural migration and a population augmentation program. A long-term dataset of grizzly bear microsatellite genotypes from 1973 to 2021 presented a unique opportunity to examine genetic trends in these populations over time. We used this dataset of 464 bears to evaluate if gene flow affected observed heterozygosity (HO), expected heterozygosity (HE), allelic richness (AR), and average pairwise relatedness (r) in each of these populations. We also estimated effective population size (Ne) using the temporal and linkage disequilibrium (LD) methods. Post gene flow, AR increased in the Selkirk and Cabinet populations and r decreased in all three populations. We did not observe any significant changes in HE or HO, but HE values in our populations were significantly higher than those estimated using a model without gene flow. Our Ne estimates were consistent between the temporal and LD methods and ranged from 15.2 to 15.8, 15.4–17.5, and 5.6–8.9 for the Selkirk, Yaak, and Cabinet populations, respectively. Overall, our findings indicate that gene flow is increasing or maintaining genetic diversity in these populations. However, Ne remains low and additional connectivity or augmentation may be needed, particularly in the Cabinet population.

Conservation planning and decision-making can be enhanced by ecological models that reliably transfer to times and places beyond those where models were developed. Transferrable models can be especially helpful for species of conservation concern, such as grizzly bears (Ursus arctos). Currently, only four grizzly bear populations remain in the contiguous United States. We evaluated transferability of previously derived individual-based, integrated step selection functions (iSSFs) developed from GPS-collared grizzly bears in the Northern Continental Divide Ecosystem by applying them within the nearby Selkirk (SE), Cabinet-Yaak (CYE), and Greater Yellowstone Ecosystems (GYE). We simulated 100 replicates of 5000 steps for each iSSF in each ecosystem, summarized relative use into 10 equal-area classes for each sex, and overlaid GPS locations from bears in the SE, CYE, and GYE on resulting maps. Spearman rank correlations between numbers of locations and class rank were >= 0.96 within each study area, indicating models were highly predictive of grizzly bear space use in these nearby populations. Assessment of models using smaller subsets of data in space and time demonstrated generally high predictive accuracy for females. Although generally high across space and time, predictive accuracy for males was low within some watersheds and in summer within the SE and CYE, potentially due to seasonal effects, vegetation, and food assemblage differences. Altogether, these results demonstrated high transferability of our models to landscapes in the Northern Rocky Mountains, suggesting they may be used to evaluate habitat suitability and connectivity throughout the region to benefit conservation planning.

The influence of bottom-up food resources and top-down mortality risk underlies the demographic trajectory of wildlife populations. For species of conservation concern, understanding the factors driving population dynamics is crucial to effective management and, ultimately, conservation. In southeastern British Columbia, Canada, populations of the mostly omnivorous grizzly bear (Ursus arctos) are fragmented into a mosaic of small isolated or larger partially connected sub-populations. They obtain most of their energy from vegetative resources that are also influenced by human activities. Roads and associated motorized human access shape availability of food resources but also displace bears and facilitate human-caused mortality. Effective grizzly bear management requires an understanding of the relationship between habitat quality and mortality risk. We integrated analyses of bottom-up and top-down demographic parameters to understand and inform a comprehensive and efficient management paradigm across the region. Black huckleberry (Vaccinium membranaceum) is the key high-energy food for grizzly bears in much of southeastern British Columbia. Little is known about where and why huckleberries grow into patches that are useful for grizzly bears (i.e., densely clustered fruiting shrubs that provide efficient access to high energy food) and how forage supply and mortality risk influence population vital rates. By following 43 grizzly bears tracked with global positioning system (GPS) collars (57 bear years) in a 14,236-km(2) focal area spanning the Selkirk and Purcell mountain ranges, we developed a model to identify huckleberry patches from grizzly bear use data. Over 2 years we visited 512 sites used by bears, identifying more than 300 huckleberry patches. We used boosted regression tree modeling associating geophysical, ecological, soil, climate, and topographical variables with huckleberry patches. We integrated this modeled food layer depicting an important pre-hibernation resource, into broader bottom-up and top-down analyses. In addition to berries, we examined bottom-up variables indexing vegetative productivity that were previously found to be predictive of bear use (e.g., alpine, canopy cover, greenness, riparian). We also examined top-down variables including road presence, road density, distance-to-road, secure habitat (defined as 500m away from a road open to vehicular access), highways, human development, and terrain ruggedness. We evaluated the relationship of these variables to female habitat selection, fitness, and population density, testing the predictability and interrelatedness of covariates relative to bottom-up and top-down influences. We estimated resource selection functions with 20,293 GPS telemetry locations collected over 10 years from 20 female grizzly bears. We modeled fitness using logistic regression of spatially explicit reproductive data derived from genetically identified family pedigrees consisting of a mother, father, and offspring. Data included 33 mothers and 72 offspring (1-8 offspring per female). We estimated density through spatial capture-recapture analysis of 126 grizzly bears detected with hair-sampled DNA 287 times between 1998 and 2005. In all 3 analyses (habitat selection, fitness, and density), huckleberry patches were the most influential bottom-up factor and secure habitat was the most consistent top-down variable (road density was similarly predictive). All of the best supported models contained bottom-up and top-down variables except the male density model, which only contained a top-down variable (secure habitat). These results suggest that both bottom-up and top-down forces drive several population processes of grizzly bears in the region, especially for females. We found that 38% of huckleberry patches (235 km(2)) predicted by the top model were in non-secure habitat and that these patches were associated with lower fitness and density relative to those in secure habitat. Grizzly bear density was 2.6 times higher in habitat with road densities <0.6 km/km(2), supporting the use of this road density target for management. The models predict that applying motorized access controls to backcountry areas with huckleberry patches would increase grizzly bear abundance by 23% on average across the region and 125% in the lowest density portion of the study area (Yahk). Managing both bottom-up and top-down influences is necessary to best mitigate the expanding human footprint, which is affecting many carnivore species worldwide. We provide evidence that bottom-up forces were more influential for female habitat selection, fitness, and density than top-down effects. We also uncovered a critical pattern in the magnitude of top-down and bottom-up influences on behavioral (habitat selection) and demographic (population density and fitness) responses. We show that the relative influence of top-down influences on habitat selection and fitness are relatively weak compared to bottom-up influences, whereas top-down pressures exert much stronger limiting forces on population density. Forming conservation decisions around behavioral responses alone may misdirect actions and have limited benefits to populations. This insight can facilitate more effective decision-making for grizzly bear conservation. Our findings highlight the importance of considering both bottom-up and top-down influences, suggesting cautious interpretation of habitat selection models for any species. A comprehensive examination with population-level metrics such as density, vital rates, and fitness may be needed for effective management.

Abstract: Population fragmentation is stressing wildlife species worldwide. In populations with minimal genetic structure across potential fractures, detecting fragmentation can be challenging. Here we apply a relatively unused approach, genetic pedigree analysis, to detect fragmentation in the American black bear (Ursus americanus) across 2 highway corridors that are bordered by large, contiguous populations. We compared our results with movements detected through Global Positioning System (GPS) telemetry of collared bears between 2005 and 2010. We used 20-locus microsatellite genotypes to identify 104 first-order relatives (parent–offspring or full siblings) within 383 black bears, sampled between 2002 and 2012. We compared numbers of pairs of immediate relatives found on either side of 2 highways—U.S. Highway 2 in northwestern Montana, USA, and BC Highway 3 in southeastern British Columbia, Canada—with an expected rate, the mean across 22 lines parallel to each highway at 1-km intervals. We found that over similar geographic scales, dispersal was lower across the transportation corridors than adjacent areas without a highway corridor. The observed number of migrants across Highway 2 was 3, well below the confidence interval of the expected number of 15.1 migrants/available bears (95% CI = 12.2–18.0). Highway 3 had 6 migrants, compared with the expected 13.1 bears (95% CI = 10.8–15.5). None of 16 black bears wearing GPS radiocollars for 1 year crossed Highway 2, yet 6 of 18 crossed Highway 3. These results suggest that even though 33% of radiocollared black bears crossed Highway 3, there appeared to be less dispersal across the transportation corridors than across other regions in the study area. Pedigree and telemetry results were more closely aligned in the Highway 2 system, with both methods suggesting more intense fragmentation than we found along Highway 3. Our results identified pedigree analysis as another tool for investigating population fragmentation, particularly in situations where genetic differentiation is too weak to determine migration rates using individual-based methods, such as population assignment.

The worldwide decline of large carnivores is concerning, particularly given the important roles they play in shaping ecosystems and conserving biodiversity. Estimating the capacity of an ecosystem to support a large carnivore population is essential for establishing reasonable and quantifiable recovery goals, determining how population recovery may rely on connectivity, and determining the feasibility of investing limited public resources toward recovery. We present a case study that synthesized advances in habitat selection and spatially-explicit individual-based population modeling, while integrating habitat data, human activities, demographic parameters and complex life histories to estimate grizzly bear carrying capacity in the North Cascades Ecosystem in Washington. Because access management plays such a critical role in wildlife conservation, we also quantified road influence on carrying capacity. Carrying capacity estimatesranged from 83 to 402 female grizzly bears. As expected, larger home ranges resulted in smaller populations and roads decreased habitat effectiveness by over 30%. Because carrying capacity was estimated with a static habitat map, the output is best interpreted as an index of habitat carrying capacity under current conditions. The mid-range scenario results of 139 females, or a total population of 278 bears, represented the most plausible scenario for this ecosystem. Grizzly bear distribution generally corresponded to areas with higher quality habitat and less road influence near the central region of the ecosystem. Our results reaffirm the North Cascades Ecosystem's capacity to support a robust grizzly bear population. Our approach, however, can assist managers anywhere ecosystem-specific information is limited. This approach may be useful to land and wildlife managers as they consider grizzly bear population recovery objectives and make important decisions relative to the conservation of wildlife populations worldwide.

Mortality resulting from human-wildlife conflicts affects wildlife populations globally. Since 2004, we have been researching conservation issues and implementing a comprehensive program to reduce human-bear conflicts (Ursus spp.; HBC) for 3 small, fragmented, and threatened grizzly bear (U. arctos) populations in the trans-border region of southwest Canada and northwest USA. We explored the temporal and spatial patterns of conflict mortality and found that HBC contributed significantly to the threatened status of these populations by causing decline, fragmentation, and decreased habitat effectiveness. Our program to reduce HBCs primarily included strategic private lands purchased to reduce human density in wildlife corridors, the reduction of bear attractants where human settlement and agriculture exists, and the nonlethal management of conflict bears. Attractant management strategies encompassed public education, cost-share electric fencing, bear-resistant garbage containers, and deadstock containment. We taught bear safety courses and bear spray training to increase tolerance and give people tools to avoid negative encounters with bears. We radio-collared and used nonlethal management on potential conflict bears and have a similar to 75% success rate in that the bear was alive and out of conflict situations over the life of the radio-collar. We identified important backcountry grizzly bear foraging habitat for motorized access control to reduce conflict and mortality and provide habitat security to reproductive females. Ongoing monitoring has demonstrated that our comprehensive HBC program has resulted in a significant reduction in human-caused mortality, increased inter-population connectivity, and improved habitat effectiveness. Several challenges remain, however, including an increase in the numbers of young grizzly bears living adjacent to agricultural areas. Herein we discuss strategies for how to integrate conservation vision into future HBC reduction programs.

The North Cascades of Washington was one of 6 recovery areas where grizzly bears were known or believed to exist at the time of listing under the Endangered Species Act (ESA) in 1975. The North Cascades recovery plan identified the need for a National Environmental Policy Act process to evaluate a range of alternatives to restore this grizzly bear population. In January of 2017 the Draft Grizzly Bear Restoration Plan for the North Cascades Ecosystem was released for public comment by the National Park Service and the U.S. Fish and Wildlife Service. This plan evaluated four alternatives for population restoration. Alternative A was “No Action” with continued existing management practices focused on improved sanitation, poaching control, motorized access, education, and monitoring to evaluate natural restoration. Alternative B was “Ecosystem Evaluation Restoration” which would transplant up to 10 grizzly bears to the North Cascades and monitor those individuals for 2 years before deciding whether to proceed with additional releases. Alternative C was “Incremental Restoration” in which 5-7 grizzly bears per year would be transplanted to the North Cascades to achieve an initial population of 25 individuals. Monitoring would determine success of the program and the need for additional releases of bears. Alternative D was “Expedited Restoration” in which 5-7 grizzly bears/year would be transplanted to the North Cascades until a population of approximately 200 individuals was achieved. All action alternatives possess an experimental (ESA 10j) population option. The draft document is available for review and comment through March 14, 2017 at: https://parkplanning.nps.gov/projectHome.cfm?projectId=44144

Background: Most biological functions are synchronized to the environmental light: dark cycle via a circadian timekeeping system. Bears exhibit shallow torpor combined with metabolic suppression during winter dormancy. We sought to confirm that free-running circadian rhythms of body temperature (Tb) and activity were expressed in torpid grizzly (brown) bears and that they were functionally responsive to environmental light. We also measured activity and ambient light exposures in denning wild bears to determine if rhythms were evident and what the photic conditions of their natural dens were. Lastly, we used cultured skin fibroblasts obtained from captive torpid bears to assess molecular clock operation in peripheral tissues. Circadian parameters were estimated using robust wavelet transforms and maximum entropy spectral analyses.Results: Captive grizzly bears housed in constant darkness during winter dormancy expressed circadian rhythms of activity and Tb. The rhythm period of juvenile bears was significantly shorter than that of adult bears. However, the period of activity rhythms in adult captive bears was virtually identical to that of adult wild denning bears as was the strength of the activity rhythms. Similar to what has been found in other mammals, a single light exposure during the bear's active period delayed subsequent activity onsets whereas these were advanced when light was applied during the bear's inactive period. Lastly, in vitro studies confirmed the expression of molecular circadian rhythms with a period comparable to the bear's own behavioral rhythms.Conclusions: Based on these findings we conclude that the circadian system is functional in torpid bears and their peripheral tissues even when housed in constant darkness, is responsive to phase-shifting effects of light, and therefore, is a normal facet of torpid bear physiology.

ABSTRACTThe conservation status of the 2 threatened grizzly bear (Ursus arctos) populations in the Cabinet‐Yaak Ecosystem (CYE) of northern Montana and Idaho had remained unchanged since designation in 1975; however, the current demographic status of these populations was uncertain. No rigorous data on population density and distribution or analysis of recent population genetic structure were available to measure the effectiveness of conservation efforts. We used genetic detection data from hair corral, bear rub, and opportunistic sampling in traditional and spatial capture–recapture models to generate estimates of abundance and density of grizzly bears in the CYE. We calculated mean bear residency on our sampling grid from telemetry data using Huggins and Pledger models to estimate the average number of bears present and to correct our superpopulation estimates for lack of geographic closure. Estimated grizzly bear abundance (all sex and age classes) in the CYE in 2012 was 48–50 bears, approximately half the population recovery goal. Grizzly bear density in the CYE (4.3–4.5 grizzly bears/1,000 km2) was among the lowest of interior North American populations. The sizes of the Cabinet (n = 22–24) and Yaak (n = 18–22) populations were similar. Spatial models produced similar estimates of abundance and density with comparable precision without requiring radio‐telemetry data to address assumptions of geographic closure. The 2 populations in the CYE were demographically and reproductively isolated from each other and the Cabinet population was highly inbred. With parentage analysis, we documented natural migrants to the Cabinet and Yaak populations by bears born to parents in the Selkirk and Northern Continental Divide populations. These events supported data from other sources suggesting that the expansion of neighboring populations may eventually help sustain the CYE populations. However, the small size, isolation, and inbreeding documented by this study demonstrate the need for comprehensive management designed to support CYE population growth and increased connectivity and gene flow with other populations. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

ABSTRACTFragmentation is a growing threat to wildlife worldwide and managers need solutions to reverse its impacts on species' populations. Populations of grizzly bears (Ursus arctos), often considered an umbrella and focal species for large mammal conservation, are fragmented by human settlement and major highways in the trans‐border region of southern British Columbia, northern Montana, Idaho, and northeastern Washington. To improve prospects for bear movement among 5 small fragmented grizzly bear subpopulations, we asked 2 inter‐related questions: Are there preferred linkage habitats for grizzly bears across settled valleys with major highways in the fragmented trans‐border region, and if so, could we predict them using a combination of resource selection functions and human settlement patterns? We estimated a resource selection function (RSF) to identify high quality backcountry core habitat and to predict front‐country linkage areas using global positioning system (GPS) telemetry locations representing an average of 12 relocations per day from 27 grizzly bears (13F, 14M). We used RSF models and data on human presence (building density) to inform cost surfaces for connectivity network analyses identifying linkage areas based on least‐cost path, corridor, and circuit theory methods. We identified 60 trans‐border (Canada–USA) linkage areas across all major highways and settlement zones in the Purcell, Selkirk, and Cabinet Mountains encompassing 24% of total highway length. We tested the correspondence of the core and linkage areas predicted from models with grizzly bear use based on bear GPS telemetry locations and movement data. Highway crossings were relatively rare; however, 88% of 122 crossings from 13 of our bears were within predicted linkage areas (mean = 8.3 crossings/bear, SE = 2.8, range 1–31, 3 bears with 1 crossing) indicating bears use linkage habitat that could be predicted with an RSF. Long‐term persistence of small fragmented grizzly bear populations will require management of connectivity with larger populations. Linkage areas identified here could inform such efforts. © 2015 The Wildlife Society.

We use genetic detection data from concurrent hair corral and bear rub sampling to provide abundance and density estimates for the threatened grizzly bear (Ursus arctos) populations in the Cabinet Mountain and Yaak regions in northwestern Montana and northern Idaho collectively known as the Cabinet-Yaak Ecosystem (CYE). We used Huggins models in Program MARK and model averaging to generate region- and sex-specific abundance estimates. To estimate the average number of bears present, we estimated mean bear residency on our sampling grid from telemetry data and used it to correct our super population estimates for lack of geographic closure. Total grizzly bear abundance in the CYE in 2012 was 49 (95% CI: 44-62) with an average of 45 (95% CI: 42-65) present at any one time. Population size in the Cabinet and Yaak regions was equal: Cabinet: 22 (95% CI: 20-36); Yaak: 22 (95% CI: 22-39). Grizzly bear density in the CYE was 4.5 (95% CI: 3.7-5.3) grizzly bears/1000 km2. With parentage analysis, we document the first natural migrants to the critically low and interbred Cabinet population and the Yaak population by bears born to parents in neighboring populations. These events support data from other sources suggesting that the expansion of neighboring populations may eventually help sustain the CYE populations.

The remote and ecologically rich forests of northwest Montana are home to an endangered population of grizzly bears (Ursus arctos). Within the Cabinet/Yaak ecosystem, recent research suggests an average population estimate of 45 bears. While grizzly bear core-areas and security requirements have been identified in the Cabinet/Yaak ecosystem, figuring out how to best manage the lush vegetation that provides foraging opportunities within that defined habitat has yet to occur. Large portions of this designated habitat are in need of ecological restoration. Since a high percentage of the Cabinet/Yaak grizzly bear’s diet is supplied through berries, grasses, and forbs, it is crucial to develop the knowledge today that can transform portions of the forest back into the edible landscapes that were once historically abundant. Because huckleberries (Vaccinium spp.) comprise a substantial amount of the annual diet volume for Cabinet/Yaak grizzly bears, land managers are beginning to design projects with the intention of increasing the amount of huckleberry foraging opportunities on the forest. Strong anecdotal evidence suggests that huckleberry prefers minimal overstory, yet few studies have been undertaken that document the plant’s response to management. Addressed is a partnership that has formed between the Yaak Valley Forest Council, USDA Forest Service, and the USDI Fish and Wildlife Service to monitor and document the effects the vegetative treatments have on huckleberry abundance.

We used mark-recapture analysis to investigate the dynamics of a black bear (Ursus americanus) population in northern Idaho where food availability varies seasonally and annually. We conducted noninvasive genetic sampling (NGS) during 2003-2006 in the Purcell Mountains of Idaho to collect black bear DNA samples for individual identification of bears. We used a combination of both mark-recapture and genetic analyses to evaluate whether variation in vital rates and genetic substructure was a function of changing food productivity in the study area. We found a heterozygote deficiency and detected genetic substructure within a single year, suggesting we sampled multiple subpopulations (a Wahlund effect). Our mark-recapture analyses suggested this pattern was in response to interannual variation in summer berry abundance. This project demonstrated the potential pitfalls of interpreting mark-recapture data over short time periods without ancillary data that can be used to evaluate mechanisms of population change. We found NGS provided information not only for traditional mark-recapture analysis but also complimentary insights into demography gained through genetic analyses. Combining mark-recapture estimates with analyses of population genetics provides a more complete understanding of population dynamics than either method alone, thus improving ecological inferences and effective management. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.

Abstract Berry‐producing shrubs are culturally, economically, and ecologically important for both people and animals in the Pacific Northwest of the United States. We examined huckleberry (Vaccinium membranaceum) and serviceberry (Amelanchier alnifolia) productivity across the Cabinet–Yaak grizzly bear recovery zone in Northern Idaho and Western Montana. An index of annual berry productivity was measured at field plots from 1989 to 2010. Temperature, precipitation, and snow indices were derived from nearby Snowpack Telemetry (SNOTEL) stations. Huckleberry production was highest during cool springs with high July diurnal temperature ranges. April–June growing‐degree days and July temperature range explain 70% of the inter‐annual variability in huckleberry productivity. Serviceberry production was correlated with maximum snow‐water equivalent and April–June growing‐degree days, which explained 86% of the variance in annual serviceberry production. These models show potential to forecast annual berry production and to anticipate potential bear–human interactions. Further development of models is essential to better predict the potential changes in important wildlife resources in the context of climate change. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.

Population fragmentation compromises population viability, reduces a species ability to respond to climate change, and ultimately may reduce biodiversity. We studied the current state and potential causes of fragmentation in grizzly bears over approximately 1,000,000 km(2) of western Canada, the northern United States (US), and southeast Alaska. We compiled much of our data from projects undertaken with a variety of research objectives including population estimation and trend, landscape fragmentation, habitat selection, vital rates, and response to human development. Our primary analytical techniques stemmed from genetic analysis of 3,134 bears, supplemented with radiotelemetry data from 792 bears. We used 15 locus microsatellite data coupled with measures of genetic distance, isolation-by-distance (IBD) analysis, analysis of covariance (ANCOVA), linear multiple regression, multi-factorial correspondence analysis (to identify population divisions or fractures with no a priori assumption of group membership), and population-assignment methods to detect individual migrants between immediately adjacent areas. These data corroborated observations of inter-area movements from our telemetry database. In northern areas, we found a spatial genetic pattern of IBD, although there was evidence of natural fragmentation from the rugged heavily glaciated coast mountains of British Columbia (BC) and the Yukon. These results contrasted with the spatial pattern of fragmentation in more southern parts of their distribution. Near the Canada-US border area, we found extensive fragmentation that corresponded to settled mountain valleys and major highways. Genetic distances across developed valleys were elevated relative to those across undeveloped valleys in central and northern BC. In disturbed areas, most inter-area movements detected were made by male bears, with few female migrants identified. Northsouth movements within mountain ranges (Mts) and across BC Highway 3 were more common than eastwest movements across settled mountain valleys separating Mts. Our results suggest that relatively distinct subpopulations exist in this region, including the Cabinet, Selkirk South, and the decades-isolated Yellowstone populations. Current movement rates do not appear sufficient to consider the subpopulations we identify along the Canada-US border as 1 inter-breeding unit. Although we detected enough male movement to mediate gene flow, the current low rate of female movement detected among areas is insufficient to provide a demographic rescue effect between areas in the immediate future (0-15 yr). In Alberta, we found fragmentation corresponded to major eastwest highways (Highways 3, 11, 16, and 43) and most inter-area movements were made by males. Gene flow and movement rates between Alberta and BC were highest across the Continental Divide south of Highway 1 and north of Highway 16. In the central region between Highways 1 and 11, we found evidence of natural fragmentation associated with the extensive glaciers and icefields along the Continental Divide. The discontinuities that we identified would form appropriate boundaries for management units. We related sex-specific movement rates between adjacent areas to several metrics of human use (highway traffic, settlement, and human-caused mortality) to understand the causes of fragmentation. This analysis used data from 1,508 bears sampled over a 161,500-km(2) area in southeastern BC, western Alberta, northern Idaho, and northern Montana during 1979-2007.This area was bisected by numerous humantransportation and settlement corridors of varying intensity and complexity. We used multiple linear regression and ANCOVA to document the responses of female and male bears to disturbance. Males and females both demonstrated reduced movement rates with increasing settlement and traffic. However, females reduced their movement rates dramatically when settlement increased to >20% of the fracture zone. At this same threshold, male movement declined more gradually, in response to increased traffic and further settlement. In highly settled areas (>50%), both sexes had a similar reduction in movements in response to traffic, settlement, and mortality. We documented several small bear populations with male-only immigration, highlighting the importance of investigating sex-specific movements. Without female connectivity, small populations are not viable over the long term. The persistence of this regional female fragmented metapopulation likely will require strategic connectivity management. We therefore recommend enhancing female connectivity among fractured areas by securing linkage-zone habitat appropriate for female dispersal, and ensuring current large source subpopulations remain intact. The fragmentation we documented may also affect other species with similar ecological characteristics: sparse densities, slow reproduction, short male-biased dispersal, and a susceptibility to human-caused mortality and habitat degradation. Therefore, regional inter-jurisdictional efforts to manage broad landscapes for inter-area movement will likely benefit a broad spectrum of species and natural processes, particularly in light of climate change. (C) 2011 The Wildlife Society.