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Live capture is an important tool for wildlife research, conservation, and management as it allows for insight into movement, behavior, demographics, diet, and health of wildlife populations. Live capture is also used for conservation translocations or to remove animals from human‐wildlife conflict situations. Improving trapping efficiency is beneficial for ethical considerations of wildlife handling, human safety, and the best use of limited resources. American black bears (Ursus americanus) are often captured using traps. Culvert‐ and box‐style traps are frequently transported using a trailer, and some are affixed to trailers, elevating the trap from the ground. Traps can be set on the ground or on trailers to reduce the set‐up and take‐down times. Although trap elements such as length, height, and visibility can influence trapping efficiency, it is unknown whether trailer presence influences capture success. We assessed the influence of single‐axle trailer presence on capture success of trapping black bears in northeastern Alberta, Canada, during spring 2022 and 2023. We compared capture success between the 2 methods and the influence of trailer presence on age and sex class. Sixty traps were set for a total of 472 trap‐nights resulting in 133 captures of 80 individual bears. Traps set with trailers present required, on average, 1.6 times more trap‐nights per capture (4.9) than those set without trailers (3.1). When only considering new captures, traps with trailers present required 1.9 times more trap‐nights to capture a bear, at 8.5 trap‐nights/capture for traps on trailers and 4.5 trap‐nights/capture when trailers were absent. Trailer presence reduced the success of overall and initial bear captures but did not influence recapture success or the proportion of captured bear age and sex classes. We conclude that wildlife researchers and managers should consider improving trap efficiency of black bears by removing traps from trailers. [ABSTRACT FROM AUTHOR]

The present case report aims to describe a postmortem finding of a colloid goiter, without obvious clinical signs of endocrine disease in a 30-year-old American black bear (Ursus americanus) from the “Zoo” in the city of Sofia, Bulgaria. A clinical examination due to a bad general condition was performed under anesthesia and a computed tomography was conducted. After the established irreversible spondylarthrosis changes the bear was euthanized. Postmortem, the thyroid gland was pathologically examined and typical findings for a colloid goiter were observed. Hibernating mammals such as the American black bear have been shown to enter a state of physiological hypothyroidism during hibernation. Hormonal signals from the thyroid gland have been suggested to be a key mediator of hibernation. From the presented case could be assumed that the captive life conditions and the prolonged life of the zoo bears may affect the function of their thyroid gland.

Simple Summary: This case report highlights two wild juvenile American black bears that were admitted to a rehabilitation facility but were euthanized due to severe immobility and joint laxity. Known musculoskeletal diseases of young bears are usually caused by trauma in the wild, or potentially rickets (a form of malnutrition) if raised in captivity. However, Case 1 was diagnosed with abnormal cartilage development (chondrodysplasia), likely of genetic origin, and Case 2 had osteoporosis and unidentified collagen abnormalities which are both unique to the current literature. With growing black bear populations, and increasing wildlife–human interface, we advise wildlife biologists and veterinarians to monitor and evaluate similar cases to help us further understand these uncommon diseases. Severe musculoskeletal disease characterized by marked joint laxity was the cause of euthanasia in two wild juvenile American black bears (Ursus americanus) admitted to a rehabilitation facility in eastern Tennessee in 2023. Previously, almost all reported musculoskeletal diseases in this population were of traumatic etiology, even in malnourished yearlings. Case 1 was an orphaned 11-month-old male cub exhibiting disproportionate dwarfism, progressive immobility, and joint laxity. Necropsy findings suggested either chondrodysplasia or rickets, and imaging findings supported a skeletal dysplasia. Case 2 was a 14-month-old emaciated male yearling exhibiting joint laxity and immobility. Necropsy findings showed osteoporosis and serous atrophy of fat, and imaging findings were inconsistent with a skeletal dysplasia. Both cases were clinically inconsistent with rickets based on normal calcium, phosphorous, and parathyroid hormone concentrations; however, Case 1 had hypovitaminosis D (9 nmol/L) compared to healthy juvenile black bears. We hypothesize that Case 1 had a genetic chondrodysplasia while the osteoporosis of Case 2 was due to chronic malnutrition. The goal of this case report is to inform wildlife agencies and facilities to monitor for similar, non-trauma-related debilitating musculoskeletal disease in free-ranging bears and evaluate cases that allow us to further understand the disease processes involved. [ABSTRACT FROM AUTHOR]

Use of dens during winter is an important strategy for American black bears (Ursus americanus) for both energy conservation and reproduction; and occupancy of suitable den sites has implications for reproductive fitness. Denning strategies may change as a result of changing climatic conditions and habitat loss. Black bears occupy arid environments in the eastern Sierra Nevada and the western ranges of the Great Basin Ecosystem. Our objectives were to identify: (1) which physical characteristics of habitat influenced selection of den sites at multiple spatial scales and (2) which environmental factors influenced timing of entrance and exit of dens by females and males. We evaluated selection of den sites by black bears at three spatial scales (300, 1000, and 4000 m) from 2011 to 2022. Terrain ruggedness was important for selection of den sites at all spatial scales. Within a 300‐m buffer from the den, bears selected den sites with rugged terrain, lower horizontal visibility, and greater canopy cover, resulting in more concealment and protection than that of the surrounding environment. Within 1000‐ and 4000‐m buffers around each den, bears selected den sites with rugged terrain, northern aspects, and steep slopes. At the 4000‐m scale, we observed interactions between sex with slope and distance to roads; females selected den sites on steeper slopes and closer to roads than did males. Females remained in the dens longer than males by entering earlier in the autumn and exiting later in the spring. Male bears exited their dens earlier with increasing consecutive days above freezing temperatures, but that relationship was weak for females. Knowing what characteristics are important for selection of den sites, and influence timing of denning, will be important for understanding how shifting climatic patterns will affect bears, particularly in arid environments that may be prone to wider fluctuations in climatic drivers of denning in the future. [ABSTRACT FROM AUTHOR]

Wildlife space use is a key component to consider when determining effective conservation and management practices. Home range size and resource selection can vary temporally and spatially depending on mortality risks in the area and access to food resources. Lands used for coal mining can contain unique mortality risks and food resources for American black bears (Ursus americanus) relative to surrounding landscapes due to hunting restrictions, vegetation planted as part of the reclamation process, and other anthropogenic food resources. We examined the influence of mining sites on resource selection of female black bears in southern West Virginia, USA, during 2007 and 2008. We estimated home range size with Brownian Bridge movement models and evaluated variation in home range size with mixed‐effects linear regression. We evaluated resource selection with mixed‐effects Poisson point process models. On mine sites, the mean 95% home range for female black bears was 1,996 ha (SD = 2,633) in the autumn and 544 ha (SD = 238) in the spring, and on non‐mine sites the mean 95% home range was 1,926 ha (SD = 1,292) in the autumn and 771 ha (SD = 480) in the spring. Our resource selection model indicated black bears used nonhunting zones associated with mine lands much greater than their availability, and that black bears in mine areas disproportionately used areas in close proximity to anthropogenic structures. Interannual variation in home range size was likely associated with mast conditions, because smaller home ranges were associated with high mast production. Our data suggest black bears may be using non‐hunting zones within mine lands as refugia from hunting and are using anthropogenic food sources available at refuse sites on mine lands, which may increase regional black bear populations in areas with high mining activity. [ABSTRACT FROM AUTHOR]

The prevalence, intensity, or outcome of interference competition and interspecific killing between predominantly solitary species operating on large spatial scales is challenging to document or test. Here, we present a detailed account of inter‐ and intraspecific interactions from contemporaneous GPS location data and in‐field investigation. In June 2018, a GPS‐collared female cougar (Puma concolor) maintained strong site fidelity for a period of 19 days, indicative of parturition behavior and establishment of a nursery site. In early July 2018, three GPS‐collared black bears (Ursus americanus) arrived at the nursery site, after which the female cougar abandoned the site. Site investigation showed that one or more bears predated an unknown number of cougar kittens. The evidence supports ecological theory suggesting that body size, mass, or group number is an important predictor of outcome. Our observation provides an example of bears potentially making risk–reward trade‐offs by eliminating a potential competitor that at the same time provisions carrion as critical food resources. These real‐time inter‐ and intraspecies competitive interactions as documented using GPS collars allow for greater insight into individual fitness and community‐level effects. [ABSTRACT FROM AUTHOR]

From 2014-2019, 8 juvenile black bears (Ursus americanus) from different geographic regions were presented to the California Department of Fish and Wildlife because of emaciation, alopecia, and exfoliative dermatitis that resulted in death or euthanasia. Autopsy and histopathology revealed that all 8 bears had generalized hyperkeratotic dermatitis, folliculitis, and furunculosis. Skin structures were heavily colonized by fungal hyphae and arthrospores; fungal cultures of skin from 7 bears yielded Trichophyton equinum, a zoophilic dermatophyte reported only rarely in non-equid species. Additional skin conditions included mites (5), ticks (2), and coagulase-negative Staphylococcus sp. infections (2). No other causes of morbidity or mortality were identified. Molecular comparisons performed at the University of Texas Fungal Reference Laboratory determined that all isolates produced identical banding patterns, potentially representing a clonal population. Dermatophytosis is commonly localized and limited to the stratum corneum of the epidermis and hair follicles. Generalized disease with dermal involvement is rare in immunocompetent individuals; illness, malnutrition, age, or immunosuppression may increase susceptibility. Underlying causes for the severe disease impact in these bears were not evident after physical or postmortem examination. The mechanism by which bears from different geographic locations had severe, T. equinum-associated dermatophytosis from a potentially clonal dermatophyte could not be explained and warrants further investigation.

Hibernation is a period of metabolic suppression utilized by many small and large mammal species to survive during winter periods. As the underlying cellular and molecular mechanisms remain incompletely understood, our study aimed to determine whether skeletal muscle myosin and its metabolic efficiency undergo alterations during hibernation to optimize energy utilization. We isolated muscle fibers from small hibernators, Ictidomys tridecemlineatus and Eliomys quercinus and larger hibernators, Ursus arctos and Ursus americanus. We then conducted loaded Mant-ATP chase experiments alongside X-ray diffraction to measure resting myosin dynamics and its ATP demand. In parallel, we performed multiple proteomics analyses. Our results showed a preservation of myosin structure in U. arctos and U. americanus during hibernation, whilst in I. tridecemlineatus and E. quercinus, changes in myosin metabolic states during torpor unexpectedly led to higher levels in energy expenditure of type II, fast-twitch muscle fibers at ambient lab temperatures (20 °C). Upon repeating loaded Mant-ATP chase experiments at 8 °C (near the body temperature of torpid animals), we found that myosin ATP consumption in type II muscle fibers was reduced by 77–107% during torpor compared to active periods. Additionally, we observed Myh2 hyper-phosphorylation during torpor in I. tridecemilineatus, which was predicted to stabilize the myosin molecule. This may act as a potential molecular mechanism mitigating myosin-associated increases in skeletal muscle energy expenditure during periods of torpor in response to cold exposure. Altogether, we demonstrate that resting myosin is altered in hibernating mammals, contributing to significant changes to the ATP consumption of skeletal muscle. Additionally, we observe that it is further altered in response to cold exposure and highlight myosin as a potentially contributor to skeletal muscle non-shivering thermogenesis.

Abstract The prevalence, intensity, or outcome of interference competition and interspecific killing between predominantly solitary species operating on large spatial scales is challenging to document or test. Here, we present a detailed account of inter‐ and intraspecific interactions from contemporaneous GPS location data and in‐field investigation. In June 2018, a GPS‐collared female cougar (Puma concolor) maintained strong site fidelity for a period of 19 days, indicative of parturition behavior and establishment of a nursery site. In early July 2018, three GPS‐collared black bears (Ursus americanus) arrived at the nursery site, after which the female cougar abandoned the site. Site investigation showed that one or more bears predated an unknown number of cougar kittens. The evidence supports ecological theory suggesting that body size, mass, or group number is an important predictor of outcome. Our observation provides an example of bears potentially making risk–reward trade‐offs by eliminating a potential competitor that at the same time provisions carrion as critical food resources. These real‐time inter‐ and intraspecies competitive interactions as documented using GPS collars allow for greater insight into individual fitness and community‐level effects.

Immobilization kits including butorphanol-azaperone-medetomidine (BAM) and nalbuphine-azaperone-medetomidine can provide effective, safe, and easy-to-use protocols in bears. Nalbuphine-azaperone-medetomidine is not commercially available but may be useful for wildlife agencies because it does not contain controlled substances. This study directly compared BAM to nalbuphine-azaperone-medetomidine immobilization in 10 juvenile healthy black bears (10 mo old; four females, six males) undergoing prerelease examinations after rehabilitation. Bears were immobilized via remote delivery of 1 mL of BAM (n¼5) or nalbuphine-azaperone-medetomidine (n¼5) intramuscularly in the shoulder during December (randomized, blinded trial). Bears were intubated, monitored with an electrocardiogram, pulse oximeter, capnograph, noninvasive blood pressure cuff, and rectal thermometer, and underwent physical examination, sample collection, morphometrics, and ear-tag placement. Induction, physiologic, and recovery parameters were recorded, including arterial blood gas analysis. The anesthetic agents were antagonized with atipamezole and naltrexone. There were no differences between protocols in induction or recovery times. There were no differences between protocols in heart rate, respiratory rate, temperature, oxygen saturation, end-tidal CO2, mean arterial pressure, or blood gas analysis or any differences between male and female bears in any parameters. Bears were hypertensive and normoxemic with low oxygen saturation via pulse oximeter, but all recovered smoothly and were released within 2 h of recovery. This study supports that nalbuphineazaperone-medetomidine is clini-cally as safe and effective as BAM in American black bears. [ABSTRACT FROM AUTHOR]

Investigating spatial patterns of animal occupancy and reproduction in peripheral populations can provide insight into factors that form species range boundaries. Following historical extirpation, American black bears (Ursus americanus) recolonized the western Great Basin in Nevada from the Sierra Nevada during the late 1900s. This range expansion, however, has not continued further into the Great Basin despite the presence of additional habitat. We aimed to quantify whether reduced reproduction toward the range edge contributes to this range boundary. We analyzed black bear detections from 100 camera traps deployed across black bear distribution in western Nevada using a multistate occupancy model that quantified the probability of occupancy and reproduction (i.e., female bears with cubs occupancy) in relation to changes in habitat type and habitat amount toward the range boundary. We detected a strong effect of habitat amount and habitat type on the probability of black bear occupancy and reproduction. At similar levels of landscape‐scale habitat amount (e.g., 50%), estimated probability of occupancy for adult bears in piñon‐juniper woodlands near the range boundary was 0.39, compared to ~1.0 in Sierra Nevada mixed‐conifer forest (i.e., core habitat). Furthermore, estimated probability of cub occupancy, conditional on adult bear occupancy, in landscapes with 50% habitat was 0.32 in Great Basin piñon‐juniper woodlands, compared to 0.92 in Sierra Nevada mixed‐conifer forest. Black bear range in the western Great Basin conforms to the center–periphery hypothesis, with piñon‐juniper woodland at the range edge supporting ecologically marginal habitat for the species compared to habitat in the Sierra Nevada. Further geographic expansion of black bears in the Great Basin may be limited by lower occupancy of reproducing females in piñon‐juniper woodland. Center–periphery range dynamics may be common in large carnivore species, as their dispersal ability allows them to colonize low‐quality habitat near range edges. [ABSTRACT FROM AUTHOR]

Bear damage to western larch trees on intensively managed public and private forest lands of the Intermountain West continues to be a problem for forest managers. Bark stripping and subsequent cambium feeding by bears commences upon den emergence in the spring, when foraging options are most restrictive. Various damage reduction methods are often controversial (snaring, hunting, supplemental feeding), or do not always adequately resolve the problem (silvicultural strategies); hence, a need exists for the development of alternative nonlethal techniques to reduce damage. We tested the efficacy of three candidate repellents (Hot Sauce®, Tree Guard™, and grizzly bear feces) to reduce spring/summer bear damage to western larch trees on reforestation units in northern Idaho. Plots were laid out and treated in early June and examined for damage four months later. Thirty-four of 300 (11.3%) treated trees were damaged by black bears. Of the newly damaged trees, the highest damage rates were on the control plots: 15 of 75 (20%) trees. Damage levels to trees on treatment plots were 8-9.3%. Mean area of damage, or bark removal, on newly damaged trees only, was 452.8 cm2. Almost half (47%) of the bear-damaged trees were completely girdled. Chi-square contingency table analysis showed that the damage rate of treated trees was less than of control trees. No difference in mean surface area of damage was detected among treatments. Further testing is necessary to reveal the true potential of chemical repellents for reducing black bear damage to conifers in the spring. A wide array of chemicals should be evaluated for their potential.

Simple Summary: I trained an American black bear in human care to choose different response buttons when presented with an image of either a highly preferred or a less preferred food item. The bear learned to choose the appropriate response button when presented with the preferred food item at above chance levels and differentiated between the use of the buttons appropriately. However, she did not reach a high level of performance with the less preferred food item even after over 1000 trials, suggesting that performing a conditional discrimination on the basis of preferences may be challenging for black bears. However, the work presented here represents the first attempt to train a bear to indicate her relative preferences using something like a Likert scale commonly used with humans to indicate their preferences and could be a valuable welfare tool for animals in human care. Similar work with gorillas suggests that bears are as capable as great apes in learning such tasks and would also benefit from this type of technical enrichment. A preference scale for use by nonhuman animals would allow them to communicate their degree of liking for individual items rather than just relative preferences between pairs of items. It would also allow animals to report liking for images of objects that would be difficult to directly interact with (e.g., potential mates and habitat modifications). Such scales can easily be presented using touchscreen technology. Few zoos have used touchscreen technology for species other than nonhuman primates. I present a description of efforts taken to create such a scale for use with a single zoo-housed American black bear (Ursus americanus). Although the bear did not reach a high level of proficiency with assigning preferred and non-preferred food items to categorical responses of "like" and "dislike," she was able to learn how to use the like and dislike buttons differentially for a single preferred and less preferred food item and she selected the correct response button for the preferred item at above chance levels. These data contribute to our limited understanding of black bear cognition and suggest that conditional discriminations may be difficult for black bears. This finding can inform continued efforts to create a simpler tool for nonhumans to communicate their preferences to human caregivers in a more nuanced way than is currently possible. More generally, the current study contributes to the growing body of work supporting the use of touchscreen technology for providing enrichment to less studied species like bears. [ABSTRACT FROM AUTHOR]

Human-bear (Ursus spp.) interactions (HBI) commonly occur in residential areas throughout North America. Negative HBI can be alleviated by using bear-resistant garbage cans (BRC) and by securing other bear attractants (e.g., bird feeders). Since the early 2000s, human and Florida black bear (U. americanus floridanus) densities have increased substantially throughout Florida, USA, concurrently producing an increase in HBI. In central Florida, an area with high densities of humans and black bears, we surveyed 2 neighborhoods that occurred in an urban ordinance zone established in 2016 that required residents to secure anthropogenic food sources. Residents were supplied with BRC in 2017, and our surveys in 2017 and 2018 assessed the changes in HBI in the year before and after receiving BRC as well as the attitudes of residents toward ordinance measures and the perceived effectiveness of BRC. We found that a combination of preventive measures practiced by residents along with use of BRC effectively reduced HBI by 54%, especially bears eating garbage (reduced to 0%). Consequently, residents spent more time outdoors in their neighborhoods and experienced an elevated quality of life because fear of HBI lessened. We also analyzed public calls to the Florida Fish and Wildlife Conservation Commission concerning HBI. Public calls declined during the 5 years after the ordinance was established compared to 5 years prior. A reduction in HBI (especially conflicts) and public acceptance of using BRC is a long-term goal for management of black bears in Florida. [ABSTRACT FROM AUTHOR]

Tick abundance and diagnosed cases of tick-borne diseases have been increasing in the United States. American black bear (Ursus americanus) populations have also been increasing in the eastern United States. As a competent host of several species of ticks and a mammal capable of traveling long distances, the role of black bears as hosts for ticks requires further evaluation. Ectoparasite surveys were conducted on black bears in Pennsylvania to evaluate tick presence, abundance, spatial distribution, and association with Sarcoptes scabiei, the etiological agent of sarcoptic mange, on bears to better understand their role in tick ecology and to improve on-host surveillance techniques. Tick burden was evaluated using standard area sampling (10.16 × 10.16 cm squares) on pre-designated body regions on black bears from June 2018–December 2019. In total, 278 unique individual black bears were evaluated, with all ticks identified as Ixodes scapularis (n = 1976; 76.7% adults, 23.3% immatures). Tick presence differed by body region on bears, with the highest percentage of tick observations located on bear ears and muzzle. Ticks also partitioned on black bears by life-stage, with immature ticks primarily recorded on the lower extremities of bears and adult ticks primarily recorded on the front-quarters of bears. This includes the first known record of I. scapularis larvae parasitizing black bears, and observations of all three mobile life-stages concurrently parasitizing bears. Tick abundance was also statistically significant dependent on season, with the highest abundance of ticks recorded in spring and lowest abundance in fall. Adult ticks were less likely to be present on bears with mange. These data reveal the important role black bears may serve in tick ecology and dispersal as all three mobile life-stages of I. scapularis were found parasitizing a mammal capable of traveling far distances in a region with high numbers of Lyme disease cases.

The phylogeography of the American black bear (Ursus americanus) is characterized by isolation into glacial refugia, followed by population expansion and genetic admixture. Anthropogenic activities, including overharvest, habitat loss, and transportation infrastructure, have also influenced their landscape genetic structure. We describe the genetic structure of the American black bear in the American Southwest and northern Mexico and investigate how prehistoric and contemporary forces shaped genetic structure and influenced gene flow. Using a suite of microsatellites and a sample of 550 bears, we identified 14 subpopulations organized hierarchically following the distribution of ecoregions and mountain ranges containing black bear habitat. The pattern of subdivision we observed is more likely a product of postglacial habitat fragmentation during the Pleistocene and Holocene, rather than a consequence of contemporary anthropogenic barriers to movement during the Anthropocene. We used linear mixed‐effects models to quantify the relationship between landscape resistance and genetic distance among individuals, which indicated that both isolation by resistance and geographic distance govern gene flow. Gene flow was highest among subpopulations occupying large tracts of contiguous habitat, was reduced among subpopulations in the Madrean Sky Island Archipelago, where montane habitat exists within a lowland matrix of arid lands, and was essentially nonexistent between two isolated subpopulations. We found significant asymmetric gene flow supporting the hypothesis that bears expanded northward from a Pleistocene refugium located in the American Southwest and northern Mexico and that major highways were not yet affecting gene flow. The potential vulnerability of the species to climate change, transportation infrastructure, and the US–Mexico border wall highlights conservation challenges and opportunities for binational collaboration. [ABSTRACT FROM AUTHOR]

Mange, a parasitic skin disease caused by various species of mites, is found in free-ranging wildlife populations and has been increasingly reported in American black bears (Ursus americanus) over the last decade in New York State (NYS), USA. Our goal was to describe the geographic, seasonal, and demographic factors associated with mange in this species in NYS. Our retrospective study used historic, opportunistic data from diagnostic necropsy records and visual sighting reports collected by the NYS Wildlife Health Program from 2009 to 2018. We used chi-square tests for independence and odds ratios to examine whether geographic location, year, season, sex, age, and reason for laboratory submission were associated with mange in bears. We used maps and seasonal analysis to investigate emerging patterns. We confirmed increased black bear mange reports in recent years. Necropsy data revealed more bears submitted to the laboratory because of mange, mainly caused by Sarcoptes scabiei; females were more likely than males to present with sarcoptic mange. We found that cases of mange in the Northern Zone were widely disseminated throughout the region, whereas cases in the Southern Zone were concentrated in two areas along the Pennsylvania border. Seasonally, mange cases showed peaks occurring in late spring to early summer and in fall. Our results were on the basis of available data; a comprehensive statewide surveillance program would be useful to better understand the apparent increase in mange and its potential impact on both the welfare of individual animals and the population of black bears in NYS. Additional research on the timing of transmission dynamics associated with females in winter dens may be helpful to wildlife managers to identify strategies to mitigate deleterious spread of the disease in black bears. [ABSTRACT FROM AUTHOR]

Information about how animal abundance varies across landscapes is needed to inform management action but is costly and time‐consuming to obtain; surveys of a single population distributed over a large area can take years to complete. Surveys employing small, spatially replicated sampling units improve efficiency, but statistical estimators rely on assumptions that constrain survey design or become less reasonable as larger areas are sampled. Efficient methods that avoid assumptions about similarity of detectability or density among replicates are therefore appealing. Using simulations and data from >3500 black bears sampled on 73 independent study areas in Ontario, Canada, we (1) quantified bias induced by unmodeled spatial heterogeneity in detectability and density; (2) evaluated novel, design‐based estimators of average density across replicate study areas; and (3) evaluated two estimators of the variance of average density across study areas: an analytic estimator that assumed an underlying homogeneous spatial Poisson point process for the distribution of animals' activity centers, and an empirical estimator of variance across study areas. In simulations where detectability varied in space, assuming spatially constant detectability yielded density estimates that were negatively biased by 20% to 30%; estimating local detectability and density from local data and treating study areas as independent, equal replicates when estimating average density across study areas using the design‐based estimator yielded unbiased estimates at local and landscape scales. Similarly, detectability of black bears varied among study areas and estimates of bear density at landscape scales were higher when no information was shared across study areas when estimating detectability. This approach also maximized precision (relative SEs of estimates of average black bear density ranged from 7% to 18%) and computational efficiency. In simulations, the analytic variance estimator was robust to threefold variation in local densities but the empirical estimator performed poorly. Conducting multiple, similar SECR surveys and treating them as independent replicates during analyses allowed us to efficiently estimate density at multiple scales and extents while avoiding biases caused by pooling spatially heterogeneous data. This approach enables researchers to address a wide range of ecological or management‐related questions and is applicable with most types of SECR data. [ABSTRACT FROM AUTHOR]

Aim: Decades of research on species distributions has revealed geographic variation in species‐environment relationships for a given species. That is, the way a species uses the local environment varies across geographic space. However, the drivers underlying this variation are contested and still largely unexplored. Niche traits that are conserved should reflect the evolutionary history of a species whereas more flexible ecological traits could vary at finer scales, reflecting local adaptation. Location: North America. Methods: We used mammal observations during a 5‐year period from the iNaturalist biodiversity database and a local ensemble modelling approach to explore spatial variation in American black bear (Ursus americanus) relationships with eight ecological correlates. We tested four biologically driven hypotheses to explain the patterns of local adaptation. We evaluated non‐stationarity in ecological relationships using a Stationarity Index and tested predictive performance using an independent, national‐level animal occurrence data set. Results: We documented considerable spatial non‐stationarity in all eight environmental relationships, with the greatest spatial variation occurring in bear's relationship to climatic factors. Notably, the greatest variation in environmental relationships tended to occur along the current boundaries of the species' range, potentially representing the ecological limits to the species geographic range. We additionally documented that spatial variation in relationships with land cover and anthropogenic factors were best explained by niche conservatism at the subspecies level, whereas climatic relationships were better explained by local adaptation. Main Conclusions: Based on these results, we propose that the current distribution of American black bear is determined by an evolutionary legacy of habitat relationships unique to each subspecies combined with more fine‐scale local adaptation to climatic conditions. This result suggests that black bears should be adaptable to climatic changes over the 21st century and that management of habitat and human‐bear relationships could be considered at the subspecies level. [ABSTRACT FROM AUTHOR]

Black bear (Ursus americanus) populations in California have increased in abundance and distribution despite rising trends in the urban encroachment of wildlands. As human-black bear conflicts increase, opportunities to study the relocation of black bears in an adaptive management setting are important for improving the management of this high-profile species. Habituated black bears, some tamed and made tractable through human-controlled food conditioning, were relocated to a remote region of the Klamath Mountains to analyze home range use, survival, return rates, and mortality. Relocated black bears with known outcomes demonstrated an 80% return rate, with 55% not surviving beyond five months. Female bears established home ranges significantly larger than males, and may suggest an enhanced maternal instinct in search of similar nutritional conditions prior to relocation. This study showed that the relocation of food-conditioned black bears resulted in high return rates, poor survival, and risk to public safety.

Although most prey have multiple predator species, few studies have quantified how prey respond to the temporal niches of multiple predators which pose different levels of danger. For example, intraspecific variation in diel activity allows white‐tailed deer (Odocoileus virginianus) to reduce fawn activity overlap with coyotes (Canis latrans) but finding safe times of day may be more difficult for fawns in a multi‐predator context. We hypothesized that within a multi‐predator system, deer would allocate antipredation behavior optimally based on combined mortality risk from multiple sources, which would vary depending on fawn presence. We measured cause‐specific mortality of 777 adult (>1‐year‐old) and juvenile (1–4‐month‐old) deer and used 300 remote cameras to estimate the activity of deer, humans, and predators including American black bears (Ursus americanus), bobcats (Lynx rufus), coyotes, and wolves (Canis lupus). Predation and vehicle collisions accounted for 5.3 times greater mortality in juveniles (16% mortality from bears, coyotes, bobcats, wolves, and vehicles) compared with adults (3% mortality from coyotes, wolves, and vehicles). Deer nursery groups (i.e., ≥1 fawn present) were more diurnal than adult deer without fawns, causing fawns to have 24–38% less overlap with carnivores and 39% greater overlap with humans. Supporting our hypothesis, deer nursery groups appeared to optimize diel activity to minimize combined mortality risk. Temporal refuge for fawns was likely the result of carnivores avoiding humans, simplifying diel risk of five species into a trade‐off between diurnal humans and nocturnal carnivores. Functional redundancy among multiple predators with shared behaviors may partially explain why white‐tailed deer fawn predation rates are often similar among single‐ and multi‐predator systems. [ABSTRACT FROM AUTHOR]

Free-ranging American black bears (Ursus americanus) often share habitat with humans and domestic animals, predisposing them to anthropogenic conflicts. Rehabilitation under professional care is a management option for orphaned, injured, and/or ill bears. Across several southeastern states, rescued bears are assessed and treated at the University of Tennessee and rehabilitated at Appalachian Bear Rescue (ABR). Records from 1996–2021 showed 337 bears (170 males, 166 females, 1 unknown) from nine states were admitted to ABR. Three bears were admitted twice, resulting in 340 admissions (42 neonates <3 mo old, 206 cubs 3–12 mo, 87 yearlings 1–2 yr, and 5 adults >2 yr). Bears presented as orphans (58%), malnourished (24%), injured or ill (12%), or confiscated/other (6%). Individuals were returned to the wild (85%); died or were euthanized (12%); or were placed into professional care (3%). Of released bears, 195 had complete medical records available for evaluation; 31% were healthy upon intake while the remaining were treated successfully for malnutrition and internal parasites (49%), orthopedic (9%) and soft tissue injuries (5%), or other diseases (5%). Causes of death determined during necropsies performed (n=30) were classified as trauma (50%), developmental (13%), undetermined (13%), malnutrition (13%), infectious or inflammatory (7%), and toxicosis (3%). Despite the lack of maternal care and high prevalence of malnutrition and trauma, most bears recovered to release with appropriate husbandry and medical care. This study provides a foundation for research to further improve care of rehabilitating black bears. [ABSTRACT FROM AUTHOR]

A total of 4,846 (84.5±87.15, 3–429: mean±SD, range) subadult or adult Dirofilaria ursi were recovered from 56 American black bears (Ursus americanus) in Ontario, 1975–77. Yearling bears had fewer worms than older bears; age classes greater than 2.5 yr had similar numbers of worms. Dead worms comprised 3.7% of all worms. There was one dead worm in total in 10 yearling bears and consistently more dead worms in older bears. The occurrence of worms within local sites in bears differed over time. Increasing numbers of worms appeared first in peritracheal sites (Site 1) following 1–3 seasons of transmission, in abundance in perirenal sites (Site 2) following the second season of transmission, and in lateral and ventral trunk and abdomen plus medio-proximal legs (Site 3) following three and four seasons of transmission. Few worms occupied other sites (Site 4). The proportion of worms recovered from the four sites was 46, 30, 19.8, and 3.9%, respectively. Dead worms comprised only 3.2% of worms in the first three definitive sites but 14% of worms in other sites. These data are consistent with primary, secondary, and tertiary site preferences for mature D. ursi in this species. Circulating microfilaremia in peripheral blood was periodic in 7/10 experiments and revealed a pattern of variable numbers during the day, highest in the evening and lowest during the night. The time of high density of microfilariae in peripheral blood was synchronous with the feeding cycle of Simulium venustum, the vector of D. ursi. Immediately postmortem, microfilariae were at highest densities in blood of lungs regardless of their relative density in peripheral blood. These data can direct diagnostic efforts to maximize detection of adult D. ursi in tissues and larvae in blood samples of naturally infected bears. [ABSTRACT FROM AUTHOR]

Spatial capture–recapture (SCR) models are powerful analytical tools that have become the standard for estimating abundance and density of wild animal populations. When sampling populations to implement SCR, the number of unique individuals detected, total recaptures, and unique spatial relocations can be highly variable. These sample sizes influence the precision and accuracy of model parameter estimates. Testing the performance of SCR models with sparse empirical data sets typical of low‐density, wide‐ranging species can inform the threshold at which a more integrated modeling approach with additional data sources or additional years of monitoring may be required to achieve reliable, precise parameter estimates. Using a multi‐site, multi‐year Utah black bear (Ursus americanus) capture–recapture data set, we evaluated factors influencing the uncertainty of SCR structural parameter estimates, specifically density, detection, and the spatial scale parameter, sigma. We also provided some of the first SCR density estimates for Utah black bear populations, which ranged from 3.85 to 74.33 bears/100 km2. Increasing total detections decreased the uncertainty of density estimates, whereas an increasing number of total recaptures and individuals with recaptures decreased the uncertainty of detection and sigma estimates, respectively. In most cases, multiple years of data were required for precise density estimates (<0.2 coefficient of variation [CV]). Across study areas there was an average decline in CV of 0.07 with the addition of another year of data. One sampled population with very high estimated bear density had an atypically low number of spatial recaptures relative to total recaptures, apparently inflating density estimates. A complementary simulation study used to assess estimate bias suggested that when <30% of recaptured individuals were spatially recaptured, density estimates were unreliable and ranged widely, in some cases to >3 times the simulated density. Additional research could evaluate these requirements for other density scenarios. Large numbers of individuals detected, numbers of spatial recaptures, and precision alone may not be sufficient indicators of parameter estimate reliability. We provide an evaluation of simple summary statistics of capture–recapture data sets that can provide an early signal of the need to alter sampling design or collect auxiliary data before model implementation to improve estimate precision and accuracy. [ABSTRACT FROM AUTHOR]

Societal Impact Statement Yosemite National Park, California, USA has hundreds of apple trees in orchards that were planted in the 1800s by local settlers. These orchards played a cultural role in the early history of the land that was to become a national park. Most of Yosemite’s orchards are well over one hundred years old and have reached the end of their lifespan. Genetic data has facilitated the assignment of cultivar names to historic apple trees within Yosemite and this information will be used to develop an Orchard Management Plan. Yosemite will use this Plan to balance orchard conservation with other necessities such as reducing human‐wildlife conflict from bears that enter developed areas to consume fruit from the trees. Summary Yosemite National Park, California, USA has hundreds of historic apple trees that were planted within orchards in the 1800s, prior to the establishment of the park. These apple trees have been a concern within Yosemite for decades because their fruit attracts bears and other wildlife into visitor recreation areas, causing undesirable wildlife–human interactions. Herein, 361 of Yosemite's apple trees were genotyped to determine cultivar identities. The cultivar names of 117 apple trees were identified by matching genotypic data with genetic data available for an apple cultivar reference dataset for the United States Department of Agriculture‐Agricultural Research Service (USDA‐ARS) National Plant Germplasm System as well as collections maintained by other sources. An additional 92 trees were determined to be likely cultivars because they matched genotypes in a reference set of trees whose identities are not known. A total of 152 trees had unique genotypes that did not match reference datasets. Cultivar information, made possible by having digital genetic information available, will allow for the preparation of a more comprehensive Orchard Management Plan. As such, park managers will be able use the Plan to more effectively make decisions about balancing orchard conservation with other park necessities, including eliminating the human–wildlife conflict that results from bears entering developed areas to feed on the fruit trees.

Abstract Landscape genetic analyses allow detection of fine‐scale spatial genetic structure (SGS) and quantification of effects of landscape features on gene flow and connectivity. Typically, analyses require generation of resistance surfaces. These surfaces characteristically take the form of a grid with cells that are coded to represent the degree to which landscape or environmental features promote or inhibit animal movement. How accurately resistance surfaces predict association between the landscape and movement is determined in large part by (a) the landscape features used, (b) the resistance values assigned to features, and (c) how accurately resistance surfaces represent landscape permeability. Our objective was to evaluate the performance of resistance surfaces generated using two publicly available land cover datasets that varied in how accurately they represent the actual landscape. We genotyped 365 individuals from a large black bear population (Ursus americanus) in the Northern Lower Peninsula (NLP) of Michigan, USA at 12 microsatellite loci, and evaluated the relationship between gene flow and landscape features using two different land cover datasets. We investigated the relative importance of land cover classification and accuracy on landscape resistance model performance. We detected local spatial genetic structure in Michigan's NLP black bears and found roads and land cover were significantly correlated with genetic distance. We observed similarities in model performance when different land cover datasets were used despite 21% dissimilarity in classification between the two land cover datasets. However, we did find the performance of land cover models to predict genetic distance was dependent on the way the land cover was defined. Models in which land cover was finely defined (i.e., eight land cover classes) outperformed models where land cover was defined more coarsely (i.e., habitat/non‐habitat or forest/non‐forest). Our results show that landscape genetic researchers should carefully consider how land cover classification changes inference in landscape genetic studies.

© 2015 The Authors. Stable isotope analysis is a powerful method for estimating the impacts animals have on their environment (resource use), revealing their ecological niches. We demonstrated the use of a stable isotope mixing model for measuring the ecological niches of consumers. In particular, we used the model IsotopeR to estimate the resource use of two species with complex, omnivorous diets: invasive Norway rats from the Aleutian Islands, AK, and American black bears from Yosemite National Park, CA. Marginal posterior distributions for major food sources (for populations, groups and individuals) described the resource axes that partly define the realized niches of these omnivores. We used measures of these resource axes to inform resource management in the Aleutians and Yosemite. Results from our analyses confirm that coastal rats did not rely on marine birds on rat-infested islands in the Aleutians. Instead, rats foraged primarily on terrestrial plants and preferred amphipods when they were available. We also use stable isotopes to confirm that plants and acorns are the largest contributors to black bear nutrition in Yosemite and learned that female bears foraged for acorns and pine nuts more heavily than males. Although it is unclear if Norway rats can maintain viable populations in the Aleutians without access to marine-derived animal protein, results from our analyses suggest their dependence on such nutrients. In addition, sex-specific differences in foraging for high-fat acorns and pine nuts in Yosemite suggest black bear populations in the Sierra Nevada may be limited by the productivity and health of hard mast species. As demonstrated here, stable isotope analysis has wide applicability for investigating the resource use and ecological niches of animals. We anticipate and encourage its rapid development in this fundamental field of ecology.

Remote camera use by hunters offers the potential to collect citizen‐derived data on multiple species using hunter surveys, but the effectiveness of this approach is untested. We examine whether observations from remote cameras that hunters use at their black bear (Ursus americanus) bait sites and reported via hunter surveys are an effective method to monitor species. We compared data collected from pseudo‐bear bait sites established for this study to hunter established bear bait site observations from the same study area. We also quantified observations reported on hunter surveys as a landscape index alternative to white‐tailed deer (Odocoileus virginianus) hunter indices, gray wolf (Canis lupus) surveys, and mustelid (Mustelidae) trapper indices. We did not detect a difference in hunter‐reported camera observations versus our observations for four of the six species recorded at pseudo‐bear bait sites. Hunters were over nine times more likely to report photographing wolves and nearly one third as likely to report photographing mustelids. We observed a relationship between trapper survey‐derived mustelid indices and the camera‐derived index, but not for deer or wolves. Foremost, these results emphasize the need to further evaluate the utility of remote camera data derived from hunters. The widespread use of remote cameras by hunters, the low‐cost of hunter surveys, and the potential to collect accurate community composition and occurrence/presence indices, points to the value of adding questions to hunter surveys regarding multiple species of interest. [ABSTRACT FROM AUTHOR]

Tick abundance and diagnosed cases of tick-borne diseases have been increasing in the United States. American black bear (Ursus americanus) populations have also been increasing in the eastern United States. As a competent host of several species of ticks and a mammal capable of traveling long distances, the role of black bears as hosts for ticks requires further evaluation. Ectoparasite surveys were conducted on black bears in Pennsylvania to evaluate tick presence, abundance, spatial distribution, and association with Sarcoptes scabiei, the etiological agent of sarcoptic mange , on bears to better understand their role in tick ecology and to improve on-host surveillance techniques. Tick burden was evaluated using standard area sampling (10.16 × 10.16 cm squares) on pre-designated body regions on black bears from June 2018–December 2019. In total, 278 unique individual black bears were evaluated, with all ticks identified as Ixodes scapularis (n = 1976; 76.7% adults, 23.3% immatures). Tick presence differed by body region on bears, with the highest percentage of tick observations located on bear ears and muzzle. Ticks also partitioned on black bears by life-stage, with immature ticks primarily recorded on the lower extremities of bears and adult ticks primarily recorded on the front-quarters of bears. This includes the first known record of I. scapularis larvae parasitizing black bears, and observations of all three mobile life-stages concurrently parasitizing bears. Tick abundance was also statistically significant dependent on season, with the highest abundance of ticks recorded in spring and lowest abundance in fall. Adult ticks were less likely to be present on bears with mange. These data reveal the important role black bears may serve in tick ecology and dispersal as all three mobile life-stages of I. scapularis were found parasitizing a mammal capable of traveling far distances in a region with high numbers of Lyme disease cases. [Display omitted] • First record of Ixodes scapularis larvae parasitizing black bears. • All three I. scapularis mobile life-stages concurrently parasitizing black bears. • I. scapularis life-stage segregation on black bears. • Standardized tick survey findings can be used to improve on-host surveillance. • Bears with sarcoptic mange less likely to have adult ticks present. [ABSTRACT FROM AUTHOR]

In temperate regions of the world, food resources are seasonally limited, which causes some wildlife species to seek out nutrient‐rich resources to better meet their caloric needs. Animals that utilize high‐quality resources may reap fitness benefits as they prepare for mating, migration, or hibernation. American black bears (Ursus americanus) are omnivores that consume both plant and animal food resources to meet macronutrient needs. Black bears capitalize on high‐quality food resources, such as soft mast in summer and hard mast during autumn, but we know less about the importance of resource quality during spring. Therefore, we sought to understand the relationship between the spatiotemporal variation in the availability of food and resource selection of black bears during spring. We also aimed to infer potential changes in foraging tactics, from opportunistic foraging to more active selection. Although black bears are described as opportunistic omnivores, we hypothesized they select areas with high‐quality forage when available. We instrumented 7 black bears with GPS collars in 2017 and 2018 and estimated fine‐scale resource selection with integrated step‐selection functions. We found evidence that black bear movements were influenced by forage quality of vegetative food resources. However, we failed to find evidence that black bears actively alter their movements to take advantage of seasonal neonate elk. Although black bears represent a substantial cause of mortality for neonate elk, we found that black bears likely feed on neonates encountered opportunistically while traveling between patches of high‐quality forage. Few studies have shown evidence of an omnivorous species capitalizing on spatiotemporal variation in forage quality, yet our data suggest this may be an important strategy for species with diverse diets, particularly where resources are seasonally limited. [ABSTRACT FROM AUTHOR]

Sarcocystis spp. are protozoan parasites that cause a spectrum of lesions in various hosts. Hepatic sarcocystosis and encephalitis have been described in captive American black bears (Ursus americanus) and polar bears (Ursus maritimus), and in a free-ranging grizzly bear (Ursus arctos horribilis), but have not previously been reported in free-ranging American black bears. This study aimed to characterize the presence and lesions associated with Sarcocystis spp. in free-ranging bears in British Columbia, Canada from samples submitted to the provincial diagnostic laboratory. From 2007 to 2019, 102 free-ranging American black bear and grizzly bear tissues were examined postmortem for sarcocystosis using histopathology and follow-up molecular diagnostics. Sarcocystosis was confirmed in 41 (40%) free-ranging bears including 39 American black bears and two grizzly bears. Microscopic lesions included multifocal necrotizing hepatitis, nonsuppurative encephalitis, and/or intramuscular sarcocysts with or without associated inflammation. Sarcocystosis was considered the cause of death in eight (20%) of these bears, exclusively in cubs of the year (<1 yr old). Sarcocystis canis was identified in 22/32 (69%) cases where molecular characterization was performed and was the etiologic agent associated with bears that died of sarcocystosis. Confirmed cases were distributed widely across British Columbia. While there was an alternate proximate cause of death in the other confirmed bears, sarcocystosis may have contributed. Age was a significant risk factor, with yearlings presenting more often with fulminant lesions; however, there was a sampling bias toward juvenile bear submissions due to size and ease of transport. Further research is needed to understand the disease epidemiology and significance to population health. [ABSTRACT FROM AUTHOR]

Context: Black bear connectivity studies are scarce in the southern distribution where the species is endangered. The identification of corridors is a strategy to promote conservation in human-modified landscapes. Objectives: Assess and validate long-distance corridors in the southern black bear distribution using resistance models, occurrence records, and radio-telemetry of an individual that dispersed between the Sierras Madres of Mexico. Methods: We acquired black bear occurrence records from several sources and telemetry records from one dispersal individual in northern Mexico. We generated ensemble habitat suitability models and resistance landscape surfaces to generate cumulative resistant kernel and least-cost paths to identify connectivity core areas and corridors of importance through Natural Protected Areas. Finally, we assessed long-distance corridors. Results: We developed three habitat suitability models for black bears southern range; one matches the current distribution of the species. When including radio-tracking records, the landscape resistance is reduced to arid sites with low habitat suitability. We used least resistance connectivity surfaces to merge subpopulations within each Sierra Madre. The long-distance corridor models indicate narrow routes that require individuals with plastic behavioral dispersal capacity. Almost 20% of the connectivity core areas are within Natural Protected Areas. These are the first large-scale corridors using resistance layers in the southern black bear distribution. Conclusions: Corridors can be functional for a range of temperate and dry habitat species. Landscape connectivity models should include the monitoring of dispersal individuals to identify the plasticity of organisms and the tangible barriers for them. [ABSTRACT FROM AUTHOR]

© 2015 The Authors. Stable isotope analysis is a powerful method for estimating the impacts animals have on their environment (resource use), revealing their ecological niches. We demonstrated the use of a stable isotope mixing model for measuring the ecological niches of consumers. In particular, we used the model IsotopeR to estimate the resource use of two species with complex, omnivorous diets: invasive Norway rats from the Aleutian Islands, AK, and American black bears from Yosemite National Park, CA. Marginal posterior distributions for major food sources (for populations, groups and individuals) described the resource axes that partly define the realized niches of these omnivores. We used measures of these resource axes to inform resource management in the Aleutians and Yosemite. Results from our analyses confirm that coastal rats did not rely on marine birds on rat-infested islands in the Aleutians. Instead, rats foraged primarily on terrestrial plants and preferred amphipods when they were available. We also use stable isotopes to confirm that plants and acorns are the largest contributors to black bear nutrition in Yosemite and learned that female bears foraged for acorns and pine nuts more heavily than males. Although it is unclear if Norway rats can maintain viable populations in the Aleutians without access to marine-derived animal protein, results from our analyses suggest their dependence on such nutrients. In addition, sex-specific differences in foraging for high-fat acorns and pine nuts in Yosemite suggest black bear populations in the Sierra Nevada may be limited by the productivity and health of hard mast species. As demonstrated here, stable isotope analysis has wide applicability for investigating the resource use and ecological niches of animals. We anticipate and encourage its rapid development in this fundamental field of ecology.

Silviculture was used to direct the development of young redwood stands toward old forest stand structures. Two variable-density thinning treatments and an unthinned control treatment were monitored for 10 years following treatment in young coast redwood (Sequoia sempervirens) stands in northern California, USA. The intent of these treatments was for forest restoration by accelerating the development of old forest features. The thinning treatments increased individual tree growth in both low and moderate density thinning treatments as compared to the control. The variable-density thinning also resulted in greater stand structural variability and was successful at increasing the relative proportion of redwood. Black bears (Ursus americanus) caused major damage to residual trees and showed a preference for more vigorous trees. Most of this damage occurred in the first four years after thinning. The confounding effects of thinning to favor larger trees and bear damage preferentially affecting more vigorous and large trees reduced the effectiveness of these treatments by eliminating the stems intended to form the future old forest structures. It also indicates forest managers need a conservative approach that leaves greater numbers of residual trees in redwood stands when bears are present. Thinning should leave sufficient trees to form the old forest structure plus ample allowances for bear-caused mortality. The long-term outcome of stand development in these thinned redwood forests is uncertain because of high rates of mortality in young trees.

We describe for the first time in the peer-reviewed literature observations of American black bear (Ursus americanus Pallas, 1780), grizzly bear (Ursus arctos Linnaeus, 1758), and polar bear (Ursus maritimus Phipps, 1774) at the same locations. Using remote cameras we documented 401 bear-visits of all three species at three camps in Wapusk National Park, Canada, from 2011–2017. These observations add to a growing body of evidence that grizzlies are undergoing a substantial range increase in northern Canada and the timing of our observations suggests denning locally. Polar and grizzly bears are of conservation concern regionally and internationally, so from the literature we assessed the potential effects on conservation efforts from interactions between these three species. In aggregate, those effects are likely to be positive for grizzlies and weakly negative for black and polar bears; further research is needed. Range overlap of these three species in this dynamic ecotonal region should not be viewed as a threat to any of them, but rather as an ecological response to environmental change that needs to be better understood.

Recent sarcoptic mange epizootics have affected free-ranging black bears (Ursus americanus) in the northeastern US, but not in North Carolina. To determine whether black bears in eastern North Carolina have exposure to Sarcoptes scabiei, serum samples from hunter-harvested black bears (n=45) were collected and evaluated for antibodies using a commercial enzyme-linked immunosorbent assay previously validated in black bears. No dermal lesions consistent with sarcoptic mange were identified in the sampled bears. The seroprevalence among these asymptomatic bears was 18%, with no significant difference between sexes or association with age. This suggests that exposure to Sarcoptes scabiei occurs within the population, and highlights the importance of serosurveys in regions without a history of clinical mange. [ABSTRACT FROM AUTHOR]

Black bear (Ursus americanus) populations in California have increased in abundance and distribution despite rising trends in the urban encroachment of wildlands. As human-black bear conflicts increase, opportunities to study the relocation of black bears in an adaptive management setting are important for improving the management of this highprofile species. Habituated black bears, some tamed and made tractable through human-controlled food conditioning, were relocated to a remote region of the Klamath Mountains to analyze home range use, survival, return rates, and mortality. Relocated black bears with known outcomes demonstrated an 80% return rate, with 55% not surviving beyond five months. Female bears established home ranges significantly larger than males, and may suggest an enhanced maternal instinct in search of similar nutritional conditions prior to relocation. This study showed that the relocation of food-conditioned black bears resulted in high return rates, poor survival, and risk to public safety. [ABSTRACT FROM AUTHOR]

In parts of the Pacific Northwest, black bears emerge from winter dens with depleted fat reserves and feed on mature conifers by stripping bark and consuming sugar-rich sapwood. Peeling by bears affects commercial conifers through direct loss of the tree or degraded log quality at stand harvest. Bears generally peel trees from 15-30 years old in intensively managed forests until preferred foods such as fruits and berries are available, and a single bear can peel several trees per day. Dying trees have a signature red canopy and are detected in annual aerial forest health surveys; however, trees that scar over peeling are not detected by aerial surveys. Previous studies reported results of damage summaries for northwest Oregon from flights, adjusted for bias; however, they offered no estimates of economic impact. Using landowner survey data, another study estimated an annual timber loss to bears at approximately $11.5 million across part of western Oregon. While informative, these estimates used broad assumptions to derive primary impacts and did not address secondary impacts. We used aerial health surveys, the national land cover database, and the Regional Economic Models Inc. (REMI) PI+ model to estimate the primary and secondary (indirect and induced) impacts of bear peeling in western Oregon. Because the accuracy and precision of aerial estimates (i.e., percentage of dead trees/polygon) was unknown, we calculated 4 scenarios of loss: 1%, 10%, 30%, and 100% loss. Under these scenarios, black bear damage to commercial forests negatively impacted Oregon’s gross domestic product between $0.9-$89 million annually, and resulted in an annual loss of between 11 and 1,012 jobs in the state. We will explain our methodology in this study as well as current efforts to improve the accuracy and precision of damage estimates, and ultimately our understanding of the economic impacts of black bear peeling.

Conservation and management efforts have resulted in population increases and range expansions for some apex predators, potentially changing trophic cascades and foraging behavior. Changes in sympatric carnivore and dominant scavenger populations provide opportunities to assess how carnivores affect one another. Cougars (Puma concolor) were the apex predator in the Great Basin of Nevada, USA, for over 80 years. Black bears (Ursus americanus) have recently recolonized the area and are known to heavily scavenge on cougar kills. To evaluate the impacts of sympatric, recolonizing bears on cougar foraging behavior in the Great Basin, we investigated kill sites of 31 cougars between 2009 and 2017 across a range of bear densities. We modeled the variation in feeding bout duration (number of nights spent feeding on a prey item) and the proportion of primary prey, mule deer (Odocoileus hemionus), in cougar diets using mixed‐effects models. We found that feeding bout duration was driven primarily by the size of the prey item being consumed, local bear density, and the presence of dependent kittens. The proportion of mule deer in cougar diet across all study areas declined over time, was lower for male cougars, increased with the presence of dependent kittens, and increased with higher bear densities. In sites with feral horses (Equus ferus), a novel large prey, cougar consumption of feral horses increased over time. Our results suggest that higher bear densities over time may reduce cougar feeding bout durations and influence the prey selection trade‐off for cougars when alternative, but more dangerous, large prey are available. Shifts in foraging behavior in multicarnivore systems can have cascading effects on prey selection. This study highlights the importance of measuring the impacts of sympatric apex predators and dominant scavengers on a shared resource base, providing a foundation for monitoring dynamic multipredator/scavenger systems. [ABSTRACT FROM AUTHOR]

Trichinella spp. nematodes are commonly found in bear species (Ursidae) and can pose severe health risks to humans when infective first-stage larvae are ingested in meat. Samples of tongue or masseter muscle from 22 male and 11 female American black bears (Ursus americanus; mean age 6.5 yr, range 1–16 yr) and 22 male, eight female, and one unknown sex grizzly bears (Ursus arctos; mean age 8.8 yr, range 2–28 yr), from Yukon, Canada, were tested to determine prevalence and intensity of Trichinella spp. infection. For black bears, prevalence was 20% and mean intensity was 401 larvae per gram of tissue (LPG), whereas for grizzly bears, prevalence was 71%, and mean infection intensity was 35 LPG. Isolates from all positive samples were identified as genotype Trichinella-T6 by multiplex PCR. For black bears, prevalence is the highest reported in Canada and infection intensity the highest recorded in North America. One black bear had a larval burden of 1,173 LPG, the second highest recorded in any host species. The prevalence in grizzly bears was the highest reported in Canada for this host. In total, 90% (27 of 30) of infected bears had infection burdens above the human food safety threshold of ≥1 LPG, reinforcing the importance of communicating the health risks to people consuming bear meat. [ABSTRACT FROM AUTHOR]

Archived serum samples taken between 1997 and 2017 from 170 American black bears (Ursus americanus) in the Lake Tahoe area between California and Nevada, US, were tested for Toxoplasma antibodies to assess the seroprevalence of this agent. Samples were screened using a commercial porcine Toxoplasma (enzyme-linked immunosorbent assay [ELISA]) modified with Protein A/G peroxidase and compared to a traditional fluorescent antibody test. Results were analyzed to determine if there were differences in seroprevalence based on the test used, sex of bears, or habitat usage (urban-suburban vs. wildland). No significant differences in seroprevalence were attributable to any of these parameters. The overall seropositivity for bears was 36% (62/170), with urban-suburban bears scoring lower (31%; 37/119) than rural-wildland bears (40%; 18/45). Our results strongly support the use of a Protein A/G-modified ELISA for determining Toxoplasma exposure in black bears. We found somewhat lower levels of Toxoplasma antibodies in black bears from this region than in several reports from populations in the eastern US. [ABSTRACT FROM AUTHOR]

The interspecific interactions of apex predators are integral to the function of ecological communities, but most studies have focused on understanding their top down effects. Kleptoparasitism (the stealing of procured food) by dominant scavengers can have negative effects on populations and behaviors of apex predators. We captured 7 pumas (Puma concolor) and fitted them with GPS collars to investigate potential kill sites (n = 352), some of which we monitored with camera traps (n = 58). We analyzed whether observed kleptoparasitism by American black bears (Ursus americanus) affected puma energetics and foraging behavior. We found that black bears were the most frequent scavenger of puma kills (72.4%), and we documented bears scavenging puma kills during every month. The top model for bear detection of puma kills included prey size, temperature, and canopy cover, with bears more likely to scavenge from adult black-tailed deer (Odocoileus hemionus columbianus) carcasses in warmer temperatures and under dense canopy cover. When black bear scavenging occurred, pumas spent 22% less time at their kill and incurred energetic losses. In response, pumas shortened their inter-kill intervals by 1.3 days thus increasing their kill rates. Our results demonstrate how a dominant scavenger directly mediates the foraging behavior of an apex predator. These results suggest that community interactions do not necessarily start at the top in top-down systems, and the effects of predators on prey populations can only be understood within their respective ecological communities. [ABSTRACT FROM AUTHOR]

The impact of wildlife--vehicle collisions on drivers and wildlife populations has been gaining attention in the United States. Given the established success of wildlife crossings with fencing in reducing wildlife crashes and connecting habitat, information is needed on cost-effective means of implementation for departments of transportation. When wildlife crossings are constructed, they are often built into new road projects as a series of 2 or more underpasses and/or overpass structures connected by exclusionary fencing. Given limited transportation budgets and the prevalence of maintenance activities more so than new construction in many states, enhancing existing underpasses on previously constructed roads has been recognized as a cost-effective mitigation opportunity. More research is needed, however, on the effects of adding fencing to existing underpasses, particularly those that are too far from one another to be connected with contiguous fencing. In this study, we evaluated the effectiveness of this measure when applied to isolated underpasses. Approximately 1.6 km of 2.4-m-high wildlife fencing was added to each of 2 existing underpasses, a large bridge underpass and a large box culvert, situated approximately 8 km apart from one another on Interstate 64 in Virginia, USA. We conducted a 2-year post-fencing camera monitoring study and compared the findings from a 2-year pre-fencing study with regard to collision frequencies with white-tailed deer (Odocoileus virginianus) and black bears (Ursus americanus); the use of the underpasses by wildlife; and roadside deer activity. We also evaluated deer activity data to compare different fence end designs applied at the study sites. After fencing installation, deer--vehicle collisions (DVCs) were reduced by 96.5% and 88% at the box culvert and bridge underpass, respectively, and there were no increases in DVCs within 1.6 km of the fence ends. Deer crossings increased 410% at the box culvert and 71% at the bridge underpass. Use of the culvert and bridge underpasses by other mammals increased 81% and 165%, respectively. Although deer use of the underpasses was much greater than their activity at any of the fence ends, there was relatively high deer activity at the fence ends that did not tie into a feature such as right-of-way fencing. Our study found that the addition of wildlife fencing to certain existing isolated underpasses can be a highly cost-effective means of increasing driver safety and enhancing habitat connectivity for wildlife. The benefits from crash reduction exceeded the fencing costs in 1.8 years, and fencing resulted in an average saving of >$2.3 million per site over the 25-year lifetime of the fencing. The results add to the growing body of knowledge about effective ways we can use existing infrastructure to connect wildlife habitat and increase driver safety. [ABSTRACT FROM AUTHOR]

Attacks on humans by bears (Ursus spp.) have increased in recent decades, as both human and bear populations have increased. To help mitigate the risk of future attacks, it is important to understand the circumstances in past attacks. Information and analyses exist regarding fatal attacks by both American black bears (Ursus americanus) and brown bears (U. arctos) as well as non-fatal attacks by brown bears. No similarly thorough analyses on non-fatal attacks by black bears are available. Our study addressed this information gap by analyzing all (n = 210) agency-confirmed, non-fatal attacks by black bears in the 48 conterminous United States during 2000 to 2017. Most attacks were defensive (52%), while 15% were predatory and 33% were food-motivated. Of defensive attacks, 85% were by female bears, and 91% of those females had young. Of predatory attacks, 95% were by male bears, and of food-motivated attacks, 80% were by male bears. Forty percent of defensive attacks by female bears involved dogs (Canis lupus familiaris). Sixty-four percent had an attractant present during the attack and 74% indicated there were reports of property damage by bears or of bears getting a food-reward in the area prior to the attack. A classification and regression tree model show the highest proportion of severe attacks were among a female victim who was with a dog and who fought back during an attack. When compared with previous studies of fatal attacks by black bears, which are typically predatory attacks by male bears, our results illustrate clear differences between fatal and non-fatal attacks. Our study also lends evidence to the hypothesis that dogs can trigger defensive attacks by black bears. These results have implications for risk assessment, attack mitigation, and how we advise the public to respond to an attacking bear. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Yosemite National Park, California, USA has hundreds of apple trees in orchards that were planted in the 1800s by local settlers. These orchards played a cultural role in the early history of the land that was to become a national park. Most of Yosemite's orchards are well over one hundred years old and have reached the end of their lifespan. Genetic data has facilitated the assignment of cultivar names to historic apple trees within Yosemite and this information will be used to develop an Orchard Management Plan. Yosemite will use this Plan to balance orchard conservation with other necessities such as reducing human‐wildlife conflict from bears that enter developed areas to consume fruit from the trees. Summary: Yosemite National Park, California, USA has hundreds of historic apple trees that were planted within orchards in the 1800s, prior to the establishment of the park. These apple trees have been a concern within Yosemite for decades because their fruit attracts bears and other wildlife into visitor recreation areas, causing undesirable wildlife–human interactions.Herein, 361 of Yosemite's apple trees were genotyped to determine cultivar identities. The cultivar names of 117 apple trees were identified by matching genotypic data with genetic data available for an apple cultivar reference dataset for the United States Department of Agriculture‐Agricultural Research Service (USDA‐ARS) National Plant Germplasm System as well as collections maintained by other sources.An additional 92 trees were determined to be likely cultivars because they matched genotypes in a reference set of trees whose identities are not known. A total of 152 trees had unique genotypes that did not match reference datasets.Cultivar information, made possible by having digital genetic information available, will allow for the preparation of a more comprehensive Orchard Management Plan. As such, park managers will be able use the Plan to more effectively make decisions about balancing orchard conservation with other park necessities, including eliminating the human–wildlife conflict that results from bears entering developed areas to feed on the fruit trees. [ABSTRACT FROM AUTHOR]

Trichinellosis is a zoonotic disease caused by one of the most widely distributed parasite groups in the world, Trichinella. Infection and illness in humans occurs following the consumption of undercooked meat containing larvae. Many cases of trichinellosis go unreported, but symptomatic disease can present with nausea, diarrhea, vomiting, fatigue, and in severe cases, death. Since the eradication of Trichinella from the commercial swine industry, wildlife meat, specifically black bear and feral pig, has become the main cause of human trichinellosis in the United States. California continues to be home to the majority of these cases. Despite this change in epidemiology, few studies have focused on importance of wildlife as a reservoir of human trichinellosis. The most recently reported prevalence estimate of Trichinella in California black bears was over 30 years ago, in 1977. To our knowledge, there have been no published reports on the prevalence of Trichinella in California feral pigs. Furthermore, human, black bear, and feral pig population growth, coupled with increased urban development, has created an expanding ecological niche for parasite transmission, thus increasing the risk of Trichinella infection for consumers of wildlife meat. Given the lack of contemporary data and knowledge, there is a need to generate estimates of the current burden of Trichinella in California wildlife in order to assess the foodborne risk this potentially lethal parasite poses to the public.

A major threat to mammalian carnivores is death due to human conflict, including carnivore use of anthropogenic food sources, predation of livestock, or car accidents. To reduce conflicts, it is critical to target proactive mitigations using reliable evidence on where conflict is likely to occur. We tested hypotheses about the importance of anthropogenic and environmental predictors in explaining the timing and distribution of human conflict with black bears (Ursus americanus) and cougars (Puma concolor) in a North American hotspot of human-carnivore conflict. Using reported conflict locations and spatial data in use-availability models, we estimated and mapped the probability of conflict for both species, including seasonally for bears, between 2011 and 2017. We found conflict increased for both species along the urban-wildland interface. Conflict with black bears was present in all seasons and increased with intermediate human density (i.e. suburban neighbourhoods). However, in autumn, bear conflict was more common in agricultural areas. Conversely, cougar conflict was primarily in rural areas, as their main attractant was livestock. We recommend targeting areas and times of expected conflict with proactive mitigations, such as bear-resistant garbage bins in communities adjacent to forests, electric fences that deter both carnivore species, and elimination of rural food attractants in autumn.