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American black bears (Ursus americanus Pallas, 1780) are opportunistic foragers, and across most of their range in North America, their diet is predominantly vegetation with limited consumption of vertebrates and invertebrates. However, they are also predators of ungulates, especially neonates, with regional variation in the amount of predation pressure they exert. We used scat analysis to examine the diet of black bears during the calving season in a moose (Alces alces (Linnaeus, 1758)) – woodland caribou (Rangifer tarandus caribou (Gmelin, 1788)) system in the Boreal forest of northern Ontario, Canada. Bears consumed herbaceous plants (46.5%), fruits and (or) seeds (20.0%), moose (3.3% adults; 4.3% calves), American beaver (Castor canadensis Kuhl, 1820; 8.5%), and insects (mostly ants; 4.2%). Bears had the highest consumption of moose and beaver in early spring, before switching to a more vegetation-dominated diet. We did not detect evidence of caribou consumption. Based on our results, black bear consumption of moose, particularly neonates, may warrant further investigation.

Brown bears (Ursus arctos) diverged from the cave bear lineage c. 1.2 million years ago and likely originated in Asia, where the oldest fossils belong to a Middle Pleistocene chronology. Brown bear fossils from the Middle Pleistocene are scarce in the Iberian Peninsula, especially when compared to the cave bear record and they are mainly located in the southern half of the peninsula. The oldest evidence in the Iberian Peninsula is from c. 250 ka, which is 300 ka younger than the oldest European records (~550 ka; L’Arago). Here we present the brown bear fossil assemblage from Postes cave (Fuentes de León, Extremadura, southern Iberian Peninsula). Postes cave has yielded some of the oldest evidence for brown bears in Iberia with a minimum date of 244 191±2261 a BP (number of identified specimens (NISP) = 4). Additionally, the uppermost part of the Pleistocene deposit has yielded one of the largest Middle Pleistocene brown bear collections in the Iberian Peninsula (NISP = 73) with a chronology roughly between 193 and 244 ka BP, comprising both cranial and postcranial remains and including a complete hemimandible. The Postes mandible fits well within the Middle Pleistocene brown bear range of variation, as it is significantly different in size and shape from the Holocene brown bears, based on geometric morphometric analyses. We show that these differences are due to allometry. This site provides more insight into the Middle Pleistocene morphological variation of brown bears in western Europe and underscores the need for additional Middle Pleistocene fossils in the northern half of Iberia to further test palaeobiogeographical hypotheses of this species’ entrance into the largest of the southern European peninsulas.

Human-dominated landscapes contain fragmented natural land cover interspersed throughout an urban matrix. Animals that occupy human-dominated landscapes often grow and reproduce differently than conspecifics. Female American black bears (Ursus americanus) produce litters for the first time usually at age 4 years; 2-year-olds rarely give birth. We visited winter bear dens and trapped bears in spring and summer to compare the reproductive output and weight of female black bears within the city limits of Asheville, North Carolina, and three forested rural sites in North Carolina and Virginia representative of the undeveloped habitat of Asheville. Urban yearling females weighed nearly double (45.0 kg ± 8.1 [± SD]; n = 36) that of yearling females from the three rural study sites (23.2 ± 8.5 [Pisgah], 23.6 ± 8.3 [Virginia SW], and 23.9 ± 9.7 [Virginia NW]; n = 95). Across all sites, hard mast production during the autumn, when females were cubs, did not affect their weights as yearlings. Seven of 12 (58%) 2-year-old urban bears produced 11 cubs (mean litter size = 1.6 ± 0.8), but no 2-year-old rural females produced cubs. Production of hard mast in the autumn, when females were yearlings, did not influence cub production by 2-year-old female bears at the urban site. We hypothesize that reproduction by 2-year-old bears is linked to the availability of anthropogenic food sources associated with urban environments. To inform population level management decisions, managers and researchers should quantify urban food sources and the effects on black bear life history. If high fecundity allows urban populations to sustain relatively high mortality rates, then urban bear populations may be source populations for surrounding, rural areas. Alternately, if reproduction in urban populations cannot match high time-specific or age-specific urban mortality rates, then urban populations may be sinks for the surrounding areas.

Investigating factors underlying human-wildlife conflicts in agricultural landscapes is important for both preventing crop damage and wildlife conservation. Although environments surrounding crop fields are considered causal factors, incorporating individual aspects of animals, such as demographic and physical characteristics, into the investigation may aid the prediction of how nuisance control affects wildlife population structures. Here, we assessed the relationship of corn consumption by Hokkaido brown bears (Ursus arctos) with both demographic (sex and age) and physical (body size) characteristics and environmental factors (human presence and crop accessibility). We estimated the proportion of corn in the lifespan diet for both female (n = 61) and male (n = 62) bears using carbon and nitrogen stable isotope analyses. Then, we analyzed the factors correlated with corn consumption using a generalized linear model. Female and male bears consumed corn from 1.3 to 30.9% and 1.3 to 42.0% of their lifespan diet, respectively. Corn consumption by female bears was not correlated with any explanatory variables, whereas that of male bears was positively correlated with their body size and crop accessibility but negatively correlated with human presence. Large male bears were more likely to have consumed more corn than small male bears, but the selective harvest of large bears may cause dwarfism of their overall population, impacting the local population dynamics. To reduce agricultural damage and population structure alteration of brown bears, the opportunity for them to learn to eat crops must be eliminated through border management between forests and agricultural fields and the relocation of agricultural fields when possible.

The lower molar (m1) of cave bears from Late Pleistocene localities of the Urals was studied employing the methods of traditional morphometry and geometric morphometrics. On the basis of the size and shape variation of m1, the small cave bear (Ursus ex gr. savini-rossicus) was found to have been a part of the faunas from the caves Skazka, Viasher, Dynamitnaya, Chudesnitsa, and Chernye Kosti. The small cave bear presence in faunas from the Medvezhya, Makhnevskaya Ledyanaya, Asha 1, Ignat’evskaya, and Barsuchii Dol caves was confirmed as well. The species range of the small cave bear encompassed the Northern, Middle, and Southern Urals in the Late Pleistocene. The ranges of the small cave bear and cave bear (Ursus kanivetz) overlapped from the beginning (marine isotope stage 5e) to the middle (middle marine isotope stage 3) of the Late Pleistocene.

Seeds of Whitebark Pine (Pinus albicaulis) are a major food for Grizzly Bears (Ursus arctos) in the Yellowstone ecosystem. In Canada, Grizzly Bears are known to eat Whitebark Pine seeds, but little additional information, such as the extent of such use and habitat characteristics of feeding sites, is available. Because Grizzly Bears almost always obtain Whitebark Pine seeds by excavating cones from persistent caching sites (middens) made by Red Squirrels (Tamiasciurus hudsonicus), it is possible to infer Whitebark Pine feeding when bears are located near excavated middens in Whitebark Pine stands. During 2013–2018, I conducted a retrospective study in Banff National Park using data from 23 Grizzly Bears equipped by Parks Canada staff with global positioning system (GPS) collars. My objectives were to use GPS fixes to determine the percentage of these bears that had been located in close proximity to excavated middens containing Whitebark Pine seeds and to describe the habitat at these excavated middens. I linked 15 bears (65%) to excavated middens and, by inference, consumption of Whitebark Pine seeds. Excavated middens occurred on high-elevation (mean 2103 ± 101 [SD] m), steep (mean 26° ± 8°) slopes facing mostly (96%) north through west (0–270°). Use of Whitebark Pine seeds by at least 65% of the 23 studied Grizzly Bears suggests that conservation of Whitebark Pine in Banff National Park would concomitantly benefit the at-risk population of Grizzly Bears.

Since the late 1700s, reports of polar bears (Ursus maritimus) using tools (i.e., pieces of ice or stones) to kill walruses (Odobenus rosmarus) have been passed on verbally to explorers and naturalists by their Inuit guides, based on local traditional ecological knowledge (TEK) as well as accounts of direct observations or interpretations of tracks in the snow made by the Inuit hunters who reported them. To assess the possibility that polar bears may occasionally use tools to hunt walruses in the wild, we summarize 1) observations described to early explorers and naturalists by Inuit hunters about polar bears using tools, 2) more recent documentation in the literature from Inuit hunters and scientists, and 3) recent observations of a polar bear in a zoo spontaneously using tools to access a novel food source. These observations and previously published experiments on brown bears (Ursus arctos) confirm that, in captivity, polar and brown bears are both capable of conceptualizing the use of a tool to obtain a food source that would otherwise not be accessible. Based on the information from all our sources, this may occasionally also have been the case in the wild. We suggest that possible tool use by polar bears in the wild is infrequent and mainly limited to hunting walruses because of their large size, difficulty to kill, and their possession of potentially lethal weapons for both their own defense and the direct attack of a predator.

In human‐dominated landscapes, connectivity is crucial for maintaining demographically stable mammalian populations. Here, we provide a comprehensive noninvasive genetic study for the brown bear population in the Hellenic Peninsula. We analyze its population structuring and connectivity, estimate its population size throughout its distribution, and describe its phylogeography in detail for the first time. Our results, based on 150 multilocus genotypes and on 244‐bp sequences of the mtDNA control region, show the population is comprised by three highly differentiated genetic clusters, consistent with geographical populations of Pindos, Peristeri, and Rhodope. By detecting two male bears with Rhodopean ancestry in the western demes, we provide strong evidence for the ongoing genetic connectivity of the geographically fragmented eastern and western distributions, which suggests connectivity of the larger East Balkan and Pindos‐Dinara populations. Total effective population size (Ne) was estimated to be 199 individuals, and total combined population size (NC) was 499, with each cluster showing a relatively high level of genetic variability, suggesting that migration has been sufficient to counteract genetic erosion. The mtNDA results were congruent with the microsatellite data, and the three genetic clusters were matched predominantly with an equal number of mtDNA haplotypes that belong to the brown bear Western mitochondrial lineage (Clade 1), with two haplotypes being globally new and endemic. The detection of a fourth haplotype that belongs to the Eastern lineage (Clade 3a1) in three bears from the western distribution places the southernmost secondary contact zone between the Eastern and Western lineages in Greece and generates new hypotheses about postglacial maxima migration routes. This work indicates that the genetic composition and diversity of Europe's low‐latitude fringe population are the outcome of ancient and historical events and highlight its importance for the connectivity and long‐term persistence of the species in the Balkans.

The first paleoparasitological analysis of coprolites of a cave bear (Ursus kanivetz Vereshchagin, 1973) was performed. Material for research was obtained from different deeps at the excavation of Ignatievskaya Cave (Chelyabinsk Region, Southern Urals, Russia, 54°53’N 57°46’E). Fossil coprolites were find from the excavations N 1-2, situated et the 120 meters from the entry of cave. The depth of excavations was 1.9 m. Radiocarbon analysis show that the age of cave bear bones was more than 27500 years. Coprolites were analyzed by combine method and sedimentation. Slides were viewed under the Meiji microscope with Х100 and Х400 magnification and made a pictures by the Vision camera. Eggs were defined using scientific descriptions available in the national and foreign literature. As a result from the paleoparasitological analysis, the presence Nematodes eggs was detected. Eggs are belonged to Baylisascaris transfuga Rudolphi, 1819 – specific parasite of Ursidae. Obviously, that helminth infected different species of bears already at the Late Pleistocene period and had a wide spreading. This is the first finding of the nematode B. transfuga of Pleistocene age and the first finding of parasites in the cave bear coprolites.

The use of camera traps in ecology helps affordably address questions about the distribution and density of cryptic and mobile species. The random encounter model (REM) is a camera‐trap method that has been developed to estimate population densities using unmarked individuals. However, few studies have evaluated its reliability in the field, especially considering that this method relies on parameters obtained from collared animals (i.e., average speed, in km/h), which can be difficult to acquire at low cost and effort. Our objectives were to (1) assess the reliability of this camera‐trap method and (2) evaluate the influence of parameters coming from different populations on density estimates. We estimated a reference density of black bears (Ursus americanus) in Forillon National Park (Québec, Canada) using a spatial capture–recapture estimator based on hair‐snag stations. We calculated average speed using telemetry data acquired from four different bear populations located outside our study area and estimated densities using the REM. The reference density, determined with a Bayesian spatial capture–recapture model, was 2.87 individuals/10km2 [95% CI: 2.41–3.45], which was slightly lower (although not significatively different) than the different densities estimated using REM (ranging from 4.06–5.38 bears/10km2 depending on the average speed value used). Average speed values obtained from different populations had minor impacts on REM estimates when the difference in average speed between populations was low. Bias in speed values for slow‐moving species had more influence on REM density estimates than for fast‐moving species. We pointed out that a potential overestimation of density occurs when average speed is underestimated, that is, using GPS telemetry locations with large fix‐rate intervals. Our study suggests that REM could be an affordable alternative to conventional spatial capture–recapture, but highlights the need for further research to control for potential bias associated with speed values determined using GPS telemetry data., We tested the reliability of the Random Encounter Model, a camera‐trap method, to estimate black bear densities in the same study area where we were conducting a hair‐snagging sampling with a traditional spatial capture–recapture model. We also tested the influence of a parameter (average speed) imported from other bear populations that is required to calculate the densities with this camera‐trap estimator. We conclude that the Random Encounter Model can be an affordable alternative to conventional spatial capture–recapture for black bears.

The rather limited human ability to understand animal vision and visual signalling has frequently clouded our expectations concerning the visual abilities of other animals. But there are multiple reasons to suspect that visual signalling is more widely employed by animals than previously thought. Because visibility of visual marks depends on the background in which they are seen, species spending most of their time living in dark conditions (e.g., in forests and/or having crepuscular and nocturnal habits) may rely on bright signals to enhance visual display. Here, as a result of experimental manipulations, we present, for the frst time ever, evidence supporting the use of a new channel of intraspecifc communication by a mammal species, i.e., brown bear Ursus arctos adult males relying on visual marks during mating. Bear reactions to our manipulation suggest that visual signalling could represent a widely overlooked mechanism in mammal communication, which may be more broadly employed than was previously thought

Apex predators can shape communities via cascading top–down effects, but the degree to which such effects depend on predator life history traits is largely unknown. Within carnivore guilds, complex hierarchies of dominance facilitate coexistence, whereby subordinate species avoid dominant counterparts by partitioning space, time, or both. We investigated whether a major life history trait (hibernation) in an apex carnivore (black bears Ursus americanus) mediated its top–down effects on the spatio-temporal dynamics of three sympatric mesocarnivore species (coyotes Canis latrans, bobcats Lynx rufus, and gray foxes Urocyon cinereoargenteus) across a 15,000 km2 landscape in the western USA. We compared top–down, bottom–up, and environmental effects on these mesocarnivores using an integrated modeling approach. Black bears exerted top–down effects that varied as a function of hibernation and were stronger than bottom–up or environmental impacts. High black bear activity in summer and fall appeared to buffer the most subordinate mesocarnivore (gray foxes) from competition with dominant mesocarnivores (coyotes and bobcats), which were in turn released by black bear hibernation in winter and early spring. The mesocarnivore responses occurred in space (i.e., altered occupancy and site visitation intensity) rather than time (i.e., diel activity patterns unaffected). These results suggest that the spatio-temporal dynamics of mesocarnivores in this system were principally shaped by a spatial predator cascade of interference competition mediated by black bear hibernation. Thus, certain life history traits of apex predators might facilitate coexistence among competing species over broad time scales, with complex implications for lower trophic levels.

Hair cortisol concentration (HCC) is being used increasingly to evaluate long‐term stress in many mammalian species. Most of the cortisol is assumed to passively diffuse from circulating blood into hair follicles and gradually accumulate in growing hair. However, our research with free‐ranging grizzly bears (Ursus arctos) suggests HCC increases significantly within several hours following capture, a time too brief to be explained by this mechanism alone. In this study with captive grizzly bears, we sought to determine if a brief spike in blood cortisol concentration, thus mimicking a single stressful event, would cause an increase in HCC over a 7‐day period. To do this, we administered a single intravenous dose (5 μg/kg) of cosyntropin to three captive unanaesthetised adult female grizzly bears on two occasions, during April when hair growth was arrested and during August when hair was growing. In both trials, the cosyntropin caused a two‐fold or greater increase in serum cortisol levels within 1 hr but did not appear to influence HCC at 1, 48, and 168 hr following cosyntropin administration. We conclude the cosyntropin‐induced cortisol spike was likely insignificant when compared to the adrenocortical response that occurs in free‐ranging bears when captured. We suggest further study with a larger sample of captive bears to evaluate the combined effects of anaesthesia and multiple doses of cosyntropin administered over several hours would better simulate the adrenocortical response of free‐ranging grizzly bears during capture., Administration of cosyntropin to captive grizzly bears caused increased serum cortisol levels within 1 hr. However, cosyntropin did not influence hair cortisol concentration at 1, 48, and 168 hr following administration. Cosyntropin‐induced hair cortisol levels were insignificant compared to free‐ranging bears during capture.

Arctic climate change poses serious threats to polar bears (Ursus maritimus) as reduced sea ice makes seal prey inaccessible and marine ecosystems undergo bottom-up reorganization. Polar bears' elongated skulls and reduced molar dentition, as compared to their sister species the grizzly bear (Ursus arctos), are adaptations associated with hunting seals on sea ice and a soft, lipid-rich diet of blubber and meat. With significant declines in sea ice, it is unclear if and how polar bears may be altering their diets. Clarifying polar bear dietary responses to changing climates, both today and in the past, is critical to proper conservation and management of this apex predator. This is particularly important when a dietary strategy may be maladaptive. Here, we test the hypothesis that hard-food consumption (i.e., less preferred foods including bone), inferred from dental microwear texture analysis, increased with Arctic warming. We find that polar bears demonstrate a conserved absence of hard-object feeding in Alaska through time (including approximately 1000 years ago), until the 21st century, consistent with a highly conserved and specialized diet of soft blubber and flesh. Notably, our results also suggest that some 21st-century polar bears may be consuming harder foods (e.g., increased carcass utilization, terrestrial foods including garbage), despite having skulls and metabolisms poorly suited for such a diet. Prior to the 21st century, only polar bears with larger mandibles demonstrated increased hard-object feeding, though to a much lower degree than closely related grizzly bears which regularly consume mechanically challenging foods. Polar bears, being morphologically specialized, have biomechanical constraints which may limit their ability to consume mechanically challenging diets, with dietary shifts occurring only under the most extreme scenarios. Collectively, the highly specialized diets and cranial morphology of polar bears may severely limit their ability to adapt to a warming Arctic.

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., Cougars have recently experienced the recolonization of black bears in the Great Basin, Nevada, USA, and are known to scavenge on cougar kills. We investigated the variation in feeding bout duration and the proportion of mule deer in cougar diets between 2009 and 2017 across a range of bear densities. 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, highlighting the importance of measuring the combined impacts of sympatric apex predators on shared resources and provides a foundation for monitoring dynamic multipredator systems.

Body condition in mammals fluctuates depending on energy intake and expenditure. For brown bears (Ursus arctos), high‐protein foods facilitate efficient mass gain, while lipids and carbohydrates play important roles in adjusting dietary protein content to optimal levels to maximize energy intake. On the Shiretoko Peninsula, Hokkaido, Japan, brown bears have seasonal access to high‐lipid pine nuts and high‐protein salmon. To assess seasonal and annual fluctuation in the body condition of adult female brown bears in relation to diet and reproductive status, we conducted a longitudinal study in a special wildlife protection area on the Shiretoko Peninsula during 2012–2018. First, analyses of 2,079 bear scats revealed that pine nuts accounted for 39.8% of energy intake in August and salmon accounted for 46.1% in September and that their consumption by bears varied annually. Second, we calculated the ratio of torso height to torso length as an index of body condition from 1,226 photographs of 12 adult females. Results indicated that body condition continued to decline until late August and started to increase in September when salmon consumption increased. In addition, body condition began to recover earlier in years when consumption of both pine nuts and salmon was high. Furthermore, females with offspring had poorer body condition than solitary females, in particular in late August in years with low salmon consumption. Our findings suggest that coastal and subalpine foods, which are unique to the Shiretoko Peninsula, determine the summer body condition of female brown bears, as well as their survival and reproductive success., To clarify seasonal and annual fluctuation in the body condition of adult female brown bears in relation to food habits and reproductive status, we conducted a 7‐year longitudinal study that included scat sampling and direct observation of bears in a special wildlife protection area on the Shiretoko Peninsula. Using photographic evaluation to assess the body condition of free‐ranging brown bears, we noninvasively monitored the body condition of identifiable bears throughout the study period. Our findings suggest that coastal and subalpine foods, which are unique to the Shiretoko Peninsula, determine the summer body condition of female brown bears as well as their survival and reproductive success.

This research provides the first in-depth analysis of fine-scale grizzly bear habitat selection and movement patterns in response to the linear footprints cleared for below-ground pipelines in Alberta. Using an extensive set of GPS location data from collared grizzly bears, we were able to determine that grizzly bears selected for younger pipelines (mean age since last construction~6.5 years), which are known to have a greater abundance of important bear foods. Bears also selected for wider corridors that were disturbed for construction more than once. During the spring season, sex/age class was an important predictor of grizzly bear use of pipelines, with adult female bears more likely to use these features than other sex/age classes. Examination of movement patterns revealed that pipeline density influenced grizzly bears’ movement rates and path straightness, particularly in the spring, when bears moved more slowly and movement paths were more tortuous in areas with higher pipeline densities. These movement patterns are consistent with foraging behavior and further indicate that bears are not exhibiting avoidance behaviors or displacement by pipeline features, and pipelines may be functioning as seasonally important foraging areas for grizzly bears in Alberta.

Identifying mechanisms of population change is fundamental for conserving small and declining populations and determining effective management strategies. Few studies, however, have measured the demographic components of population change for small populations of mammals (, This research investigates population dynamics in two adjacent but genetically and geographically distinct, threatened brown bear (Ursus arctos) populations in southwestern British Columbia, Canada, following the caseation of hunting in that area. Differences in independent female and cub survival between the populations resulted in population increase in the larger, partially connected population, and population decrease in the smaller, isolated population. We suggest that when populations are small and isolated, population growth is rare and, even with intensive management, becomes prohibitive for population recovery.

Reforestation, which converts abandoned farmland back into forestland by planting woody species, can provide habitat for wildlife, including the brown bear (Ursus arctos Linnaeus, 1758). In the Shiretoko World Heritage site, northern Japan, where brown bears occur at high density, conifers have been planted since the 1970s to reforest abandoned farmland. In this area, brown bears were first observed digging for cicada Lyristes bihamatus Motschulsky, 1861 = Auritibicen bihamatus (Motschulsky, 1861) nymphs from 2000. Our preliminary observations suggested that the emergence of digging behavior might be associated with reforestation. We examined whether reforestation provided a foraging habitat for brown bears. We found that digging occurred only within the restored conifer forests, but not within the natural forest. The densities of cicada nymphs in the restored forests were higher than in the natural forest. These results indicate that the reforestation of abandoned farmland provides a foraging habitat for brown bears by increasing the availability of cicada nymphs in the Shiretoko World Heritage site.

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.

El oso negro (Ursus americanus) redujo significativamente su área de distribución en México en el siglo XX. En los últimos años, sin embargo, hay evidencia de su presencia en áreas fuera del rango de distribución propuesto. El objetivo es documentar un conjunto de registros nuevos de oso negro para los estados de Guanajuato, Querétaro y San Luis Potosí en el centro-este de México. Se detectaron osos negros como resultado de acciones de monitoreo que incluyeron cámaras trampa, avistamientos y observación indirecta (huellas y eventos de depredación), realizados entre los años 2000 y 2019. Detectamos la presencia de oso negro a través de seis registros en los estados de Guanajuato, Querétaro y San Luis Potosí, en un área cercana a la distribución más sureña para esta especie en el Continente Americano. Cinco de las observaciones ocurrieron dentro de áreas naturales protegidas. Las observaciones aumentan el número de especies de mamíferos registrados en el estado de Guanajuato a 95 y confirman la presencia del oso negro en los estados de Querétaro y San Luis Potosí. Las observaciones proveen evidencia que respalda la hipótesis de que las poblaciones de oso negro del noreste de México se mueven hacia el centro-este de México a través de la Sierra Madre Oriental (SMO). La presencia de oso negro en el centro-este de México señala la necesidad de intensificar el monitoreo sistemático de la biodiversidad en la SMO y en áreas protegidas de la región a través de programas de monitoreo y conservación.

In several primates and carnivores, pronation/supination angles of the forearm skeleton were examined, and it is thought that a larger angle is useful to acquire dexterous behaviors in feeding and/or life style, including climbing. In this study, the pronation/supination angles in Asiatic black, brown and polar bears were nondestructively examined. These specimens were classified as adult or non-adult. Three or four carcasses of each group of Asiatic black and brown bears were used for CT analysis, whereas only one adult polar bear was used. The forearms were positioned within the gantry of a CT scanner in both maximally supinated and pronated states. Extracted cross-sectional CT images of two positions were superimposed by overlapping the outlines of each ulna. The centroids of the radii were detected, and then the centroid of each radius and the midpoint of a line which connects between both ends of the surface of each radius facing the ulna, were connected by lines to measure the angle of rotation as an index of pronation/supination. In adult brown and polar bears, the angles were smaller as compared with the other groups (Asiatic black and non-adult brown bears). Asiatic black and non-adult brown bears can climb trees, whereas adult brown bears and polar bears cannot. This suggests that the pronation/supination angle is related to arboreal activity in Ursidae.

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., We evaluated the performance of multiple of resistance surfaces generated from two different land cover data sets to quantify the effects of landscape features on gene flow. We observe models with land cover defined with more complexity (i.e., eight land cover classes) out performed those models that defined land cover using a binary classification scheme (i.e., habitat/non‐habitat or forest/non‐forest.) Our analyses demonstrate that different land cover data sets classifications can result in disparate landscape–genetic associations.

The brown bear (Ursus arctos L.) is an omnivorous large mammal that has an essential function in many ecosystems as a seed disperser. We studied the brown bear's role as a seed dispersal agent in a mixed temperate forest in northern Anatolia, Turkey. We collected 197 fecal samples from the field during the brown bear's active period for two consecutive years. We extracted seeds of 34 plant taxa from fecal samples. Among these taxa, 29 had intact seeds, whereas seeds of 5 were found to be entirely or mostly physically damaged. Damaged seeds belonged to fruits of acorn, capsule, nut, and drupe-like nut types, while no or few seeds from fleshy fruits such as berry, drupe, pome, and rosehip types had damage. Seeds from pome type fruits of Malus sylvestris and Pyrus elaeagnifolia had a higher germination percentage in feces than in the control (fresh seeds collected from the field), but that was quite the opposite in berries of Lonicera caucasica and Vaccinium arctostaphylos. No difference in germination percentage was found between feces and control groups in seeds from rosehips. Our results reveal that seeds of several species found in the study area are dispersed by the brown bear, especially those with fleshy fruits (e.g., Rosaceae members). In this study, we established the role of the brown bear as a seed dispersal agent in northern Anatolian mixed temperate forests. Our study suggests that fruit type is a determinant of the success of endozoochorous seed dispersal by the brown bear.

The paper summarizes numerous scattered data from the last 120 years on the former distribution of the brown bear (Ursus arctos) in Bulgaria. Data from 52 (13 fossil and 39 subfossil) sites (from the Middle Pleistocene to the 19th century AD) are presented. The brown bear former distribution was much wider than the present occurrence. The species range covered the whole territory of the country, including mountain regions, as well as vast lowland and plain landscapes. The geographical, altitudinal and chronological distribution are presented and analyzed. The record from the Kozarnika Cave (1.000,000–700,000 years BP) is one of the earliest records of this species in Europe. About 73% of the localities are situated between 100 and 500 m a. s. l. Twelve sites contain Paleolithic finds, one Mesolithic, 14 Neolithic, six Chalcolithic, five from the Bronze Age, and two from the Iron Age. The remaining 12 subrecent sites are dated to the last ca. 2,400 years. Most of the species findings came from archeological sites – prehistoric and ancient settlements. The distribution of Ursus arctos once covered the entire territory of the country, including the vast regions such as Ludogorie, Dobruja, the Danube Lowland, the Upper Thracian Lowland, as well as the Sakar, Strandja, Sredna Gora, and the Predbalkan Mts.

Scavenging, an underappreciated mechanism of prey consumption for many predators, can contribute substantially to nutritional intake. Facultative scavengers such as brown bears (Ursus arctos Linnaeus, 1758) may both kill and scavenge Pacific salmon (genus Oncorhynchus Suckley, 1861), though the extent of scavenging and factors affecting this behavior are unclear. We tagged 899 sockeye salmon (Oncorhynchus nerka (Walbaum in Artedi, 1792)) carcasses and placed them on streambanks over 5 years at multiple sites in southwestern Alaska (USA) where brown bears annually prey on spawning sockeye salmon. Examination of carcasses revealed overall scavenging rates of 15% after 1 day and 54% after 3 days. Scavenging rate varied by site and year and increased throughout the salmon run. Contrary to predictions, scavenging was more frequent in senescent or bear-killed carcasses than ripe carcasses. Carcass consumption ranged from minimal to almost complete; body and brain tissues were most frequently consumed after 3 days (68% and 63% of carcasses, respectively). We also documented secondary scavenging (i.e., tissue consumption on two separate events) and delayed scavenging (i.e., scavenging observed after 3 days but not 1 day). Taken together, the results indicated that scavenging in these streams contributes significantly to total consumption of salmon by bears, with ramifications for other components of these salmon-dependent ecosystems.

Harvest can disrupt wildlife populations by removing adults with naturally high survival. This can reshape sociospatial structure, genetic composition, fitness, and potentially affect evolution. Genetic tools can detect changes in local, fine-scale genetic structure (FGS) and assess the interplay between harvest-caused social and FGS in populations. We used data on 1614 brown bears, Ursus arctos, genotyped with 16 microsatellites, to investigate whether harvest intensity (mean low: 0.13 from 1990 to 2005, mean high: 0.28 from 2006 to 2011) caused changes in FGS among matrilines (8 matrilines; 109 females ≥4 years of age), sex-specific survival and putative dispersal distances, female spatial genetic autocorrelation, matriline persistence, and male mating patterns. Increased harvest decreased FGS of matrilines. Female dispersal distances decreased, and male reproductive success was redistributed more evenly. Adult males had lower survival during high harvest, suggesting that higher male turnover caused this redistribution and helped explain decreased structure among matrilines, despite shorter female dispersal distances. Adult female survival and survival probability of both mother and daughter were lower during high harvest, indicating that matriline persistence was also lower. Our findings indicate a crucial role of regulated harvest in shaping populations, decreasing differences among “groups,” even for solitary-living species, and potentially altering the evolutionary trajectory of wild populations. anthropogenic, dispersal, hunting, male mating, maternal, predator, survival

To assess the trophic position of the exceptionally large-sized brown bears from the Pleistocene of Yakutia, we used stable nitrogen and carbon isotope analyses of the collagen contained in fossil bones and teeth. Modern brown bears of Yakutia were compared to the large Pleistocene predators. As a result of the measurements taken for the Pleistocene bears, we obtained δ13С values typical of terrestrial ecosystems and relatively high δ15N values typical of such Pleistocene predators as the cave lion. We explain the high δ15N values of the bone collagen of the study fossil bears, as well as other Pleistocene brown bears of Yakutia and Chukotka, by (1) the absence of large competitors such as Arctodus simus, which allowed the bears to use large amounts of animal food; (2) the physiological effect of hibernation, expressed in an increased content of 15N in the bone collagen; and (3) an increased content of 15N in vegetation due to more severe climatic conditions, which affects the isotopic composition of the entire mammoth fauna of western Beringia. The δ13C and δ15N values of modern brown bears in Yakutia indicate a plant diet, suggesting that the modern brown bears (compared to fossils) occupy a fundamentally different trophic niche adapted to the modern low-productivity ecosystems of Yakutia.

Spatial capture–recapture (SCR) models have increasingly been used as a basis for combining capture–recapture data types with variable levels of individual identity information to estimate population density and other demographic parameters. Recent examples are the unmarked SCR (or spatial count model), where no individual identities are available and spatial mark–resight (SMR) where individual identities are available for only a marked subset of the population. Currently lacking, though, is a model that allows unidentified samples to be combined with identified samples when there are no separate classes of “marked” and “unmarked” individuals and when the two sample types cannot be considered as arising from two independent observation models. This is a common scenario when using noninvasive sampling methods, for example, when analyzing data on identified and unidentified photographs or scats from the same sites. Here we describe a “random thinning” SCR model that utilizes encounters of both known and unknown identity samples using a natural mechanistic dependence between samples arising from a single observation model. Our model was fitted in a Bayesian framework using NIMBLE. We investigate the improvement in parameter estimates by including the unknown identity samples, which was notable (up to 79% more precise) in low-density populations with a low rate of identified encounters. We then applied the random thinning SCR model to a noninvasive genetic sampling study of brown bear (Ursus arctos) density in Oriental Cantabrian Mountains (North Spain). Our model can improve density estimation for noninvasive sampling studies for low-density populations with low rates of individual identification, by making use of available data that might otherwise be discarded., This research has received financial support from the Spanish Ministry for the Ecological Transition and the Demographic Challenge (Government of Spain). We are grateful to the Brown Bear Foundation (Fundación Oso Pardo), and Raquel Godinho (CIBIO-InBIO, Portugal) and Jose Vicente López-Bao (University of Oviedo) for providing the original brown bear data set from the Eastern Cantabrian Mountains (Spain).

An assessment of the current state of the brown bear population (Ursus arctos meridionalis Midd. 1851) within the western Caucasus has been carried out. By the end of 2010, the range of bears is shown to have shrunk almost to the borders of Sochi National Park, the Caucasus Nature Reserve, and nearby environs. Over the last ten years, about 20 000 hectares of bear habitats were lost due to resort construction, including fall and den stations on the Aibga and Psekhako ridges, which are the most important for the species. The bear migration routes in the Mzymta River valley and the upper Pshekha area were disturbed. Food waste dumps within the bear habitats (in tourist camps and construction areas) have caused the development of synanthropic individuals. The population numbers have decreased approximately by half since the mid-1990s, but are now stable at the level of about 300 individuals. The age and sex ratios indicate a normal population structure, which is characteristic of moderately exploited bear populations. In 2013‒2018, the share of females with yearling cubs in the total number of bears ranged within 9.6–10.4%, the proportion of bear yearling cubs being 21%. Among the females with yearling cubs, 55% had one bear cub, while 35% had two cubs. On average, the number of cubs per female is 1.6 ± 0.1. The bear migration routes from the northern and southern foothills toward the highlands of the Caucasus Nature Reserve have mostly been preserved. In general, the bears have adapted to the conditions that have changed over the past ten years, and one of the adaptation mechanisms appears to be the significance of the Nature Reserve territory in the spatial structure of the bear population.

The variability of cheek teeth over time was studied with the use of univariate and multivatiate statistical analyses for 1370 tooth specimens of the Kudaro cave bear (Ursus kudarensis) (Baryshnikov 1985) collected in the Kudaro 1 and Kudaro 3 caves in the Caucasus. The material examined included two chronosubspecies: U. k. praekudarensis (middle part of the Middle Pleistocene, nearly 350 000 years ago) and U. k. kudarensis (Late Pleistocene, nearly 120 000–40 000 years ago), as well as a sample of intermediate stratigraphic position referred to as a “transitional form” (the end of the Middle Pleistocene, nearly 250 000 years ago). Our study detected no single pathway of evolutionary change in the cheek teeth of U. kudarensis, instead showing specific modifications for the premolars, molars, and even individual teeth (e.g., m3) in the context of high individual variability. In size, the teeth of U. k. praekudarensis occupied an intermediate position between the more robust teeth of the “transitional form” and the smaller teeth of U. k. kudarensis. By the range of morphometric characters (size and crown proportions), the “transitional form” was more closely related to U. k. kudarensis than to U. k. praekudarensis. At the same time, the parameters of allometric variation of the “transitional form” either related it to U. k. praekudarensis or were of the original nature. The calculated rate of evolution of the metric characters was found to be dissimilar not only for different teeth but also for different measurements of the same tooth crown, and these modifications themselves were oppositely directed. A comparison with the main evolutionary trends in European cave bears revealed the unique, independent character of evolution of the cheek teeth in the Kudaro cave bear, which is expressed to different degrees for the upper and lower rows of teeth.

Bear attacks, although rare, can inflict life-threatening injuries. We present the case of a 50-y-old woman from rural Pennsylvania who was attacked by a North American black bear, Ursus americanus. She sustained multiple complex injuries including near-complete scalp avulsion, bilateral ear avulsions, and fractures of the face, ribs, and pelvis. These injuries are similar to those sustained in other bear maulings reported in the literature and required both acute intervention and a multidisciplinary approach to recovery.