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Wildlife must increasingly balance trade‐offs between the need to access important foods and the mortality risks associated with human‐dominated landscapes. Human disturbance can profoundly influence wildlife behavior, but managers know little about the relationship between disturbance–behavior dynamics and associated consequences for foraging. We address this gap by empirically investigating the consequences of human activity on a keystone predator–prey interaction in a region with limited but varied industrial disturbance. Using stable isotope data from 226 hair samples of grizzly bears (Ursus arctos horribilis) collected from 1995 to 2014 across 22 salmon‐bearing watersheds (88,000 km2) in British Columbia, Canada, we examined how human activity influenced their consumption of spawning salmon (Oncorhynchus spp.), a fitness‐related food. Accounting for the abundance of salmon and other foods, salmon consumption strongly decreased (up to 59% for females) with increasing human disturbance (as measured by the human footprint index) in riparian zones of salmon‐bearing rivers. Declines in salmon consumption occurred with disturbance even in watersheds with low footprints. In a region currently among the least influenced by industrial activity, intensification of disturbance in river valleys is predicted to increasingly decouple bears from salmon, possibly driving associated reductions in population productivity and provisioning of salmon nutrients to terrestrial ecosystems. Accordingly, we draw on our results to make landscape‐scale and access‐related management recommendations beyond current streamside protection buffers. This work illustrates the interaction between habitat modification and food security for wildlife, highlighting the potential for unacknowledged interactions and cumulative effects in increasingly modified landscapes. [ABSTRACT FROM AUTHOR]

Commercial trade is one of the leading threats to bears as they are targeted for trophies, food and medicines. While the threat from illegal trade and trafficking has been extensively studied in Asia, understanding of bear trade dynamics outside this region is limited. Poland is an end use destination for wildlife products such as trophies and wildlife-based traditional medicines. To gain an understanding of the bear trade in Poland, we conducted an analysis of (1) seizure data, (2) Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) trade data and (3) online surveys of Polish websites. We found that the trade of bears in Poland predominantly involves a demand for traditional bear-based medicines and, to a lesser extent, trophies. While trade in bear-based medicines and trophies is permissible with appropriate permits, illegal trade in such commodities is occurring in violation of CITES and European Union Wildlife Trade Regulations and in case of brown bear specimens—also national laws. This may possibly be due to a lack of public awareness regarding laws governing the import and export of bear parts and derivatives in which case education and awareness raising programmes might prove beneficial in eradicating trafficking of bear-based medicines and trophies. The use of bear bile for traditional medicine in Eastern Europe has not been previously documented and merits further research as to its scale, the source of bears used for these purposes and the potential impacts to bear populations. [ABSTRACT FROM AUTHOR]

Abstract Wildlife must increasingly balance trade‐offs between the need to access important foods and the mortality risks associated with human‐dominated landscapes. Human disturbance can profoundly influence wildlife behavior, but managers know little about the relationship between disturbance–behavior dynamics and associated consequences for foraging. We address this gap by empirically investigating the consequences of human activity on a keystone predator–prey interaction in a region with limited but varied industrial disturbance. Using stable isotope data from 226 hair samples of grizzly bears (Ursus arctos horribilis) collected from 1995 to 2014 across 22 salmon‐bearing watersheds (88,000 km2) in British Columbia, Canada, we examined how human activity influenced their consumption of spawning salmon (Oncorhynchus spp.), a fitness‐related food. Accounting for the abundance of salmon and other foods, salmon consumption strongly decreased (up to 59% for females) with increasing human disturbance (as measured by the human footprint index) in riparian zones of salmon‐bearing rivers. Declines in salmon consumption occurred with disturbance even in watersheds with low footprints. In a region currently among the least influenced by industrial activity, intensification of disturbance in river valleys is predicted to increasingly decouple bears from salmon, possibly driving associated reductions in population productivity and provisioning of salmon nutrients to terrestrial ecosystems. Accordingly, we draw on our results to make landscape‐scale and access‐related management recommendations beyond current streamside protection buffers. This work illustrates the interaction between habitat modification and food security for wildlife, highlighting the potential for unacknowledged interactions and cumulative effects in increasingly modified landscapes.

Historical persecution of grizzly bears in North America reduced the species range by 55%. Today, dedicated recovery efforts and shifting societal perceptions have supported the recovery and expansion of grizzly bear populations in many areas. With increasing overlap between people and bears, conservation actions and scientific inquiry are now shifting efforts toward supporting coexistence with bears. Here, we assessed the demography and behavior of grizzly bears in a coexistence landscape in southeast British Columbia, Canada, where abundant grizzly bear populations occur among busy, human‐settled valleys. Between 2016 and 2022, we captured 76 individual grizzly bears and monitored their conflict behavior, survival, and reproduction for 160 animal‐years. The cause of death for 14 animals with a functioning collar was human–wildlife conflict (n = 6), road or rail collision (n = 6), unknown but human suspected (n = 1), and natural (n = 1). Subadult survival was the lowest recorded in North America, while adult survival was similar to other studies, suggesting an intense demographic filter for young animals. We estimate that human‐caused mortality is underreported in government databases by 65%, or for every recorded mortality, there are ~2 that go unreported. Reporting was especially low for road and rail mortalities. Grizzly bear mortality in the Elk Valley due to collisions and conflicts with people is an order of magnitude greater than elsewhere in British Columbia. Combining DNA‐ and collar‐based estimates of population growth, we show that grizzly bear abundance is stable due to source‐sink dynamics, whereby ~7 immigrant bears per year offset the high mortality rates in the area. Grizzly bears dispersing into the valley are often young and more conflict‐naïve, creating a conflict spiral that can be interrupted by reducing mortality of young animals. Creating a self‐sustaining population of bears in the Elk Valley that is not reliant on immigration will require targeted efforts to reduce or secure attractants on private property and strategies to minimize collisions with trains and vehicles. [ABSTRACT FROM AUTHOR]

Abstract Historical persecution of grizzly bears in North America reduced the species range by 55%. Today, dedicated recovery efforts and shifting societal perceptions have supported the recovery and expansion of grizzly bear populations in many areas. With increasing overlap between people and bears, conservation actions and scientific inquiry are now shifting efforts toward supporting coexistence with bears. Here, we assessed the demography and behavior of grizzly bears in a coexistence landscape in southeast British Columbia, Canada, where abundant grizzly bear populations occur among busy, human‐settled valleys. Between 2016 and 2022, we captured 76 individual grizzly bears and monitored their conflict behavior, survival, and reproduction for 160 animal‐years. The cause of death for 14 animals with a functioning collar was human–wildlife conflict (n = 6), road or rail collision (n = 6), unknown but human suspected (n = 1), and natural (n = 1). Subadult survival was the lowest recorded in North America, while adult survival was similar to other studies, suggesting an intense demographic filter for young animals. We estimate that human‐caused mortality is underreported in government databases by 65%, or for every recorded mortality, there are ~2 that go unreported. Reporting was especially low for road and rail mortalities. Grizzly bear mortality in the Elk Valley due to collisions and conflicts with people is an order of magnitude greater than elsewhere in British Columbia. Combining DNA‐ and collar‐based estimates of population growth, we show that grizzly bear abundance is stable due to source‐sink dynamics, whereby ~7 immigrant bears per year offset the high mortality rates in the area. Grizzly bears dispersing into the valley are often young and more conflict‐naïve, creating a conflict spiral that can be interrupted by reducing mortality of young animals. Creating a self‐sustaining population of bears in the Elk Valley that is not reliant on immigration will require targeted efforts to reduce or secure attractants on private property and strategies to minimize collisions with trains and vehicles.

Species at the periphery of their range are typically limited in density by poor habitat quality. As a result, the central–marginal hypothesis (CMH) predicts a decline in genetic diversity of populations toward the periphery of a species' range. Grizzly bears (Ursus arctos) once ranged throughout most of North America but have been extirpated from nearly half of their former range, mainly in the south. They are considered a species at risk even in Canada's remote North, where they occupy the northernmost edge of the species' continental distribution in a low‐productivity tundra environment. With climate change, one of their main prey species in the tundra (caribou), which has always shown yearly fluctuations, is declining, but simultaneously, grizzlies appear to be expanding their range northward in the same tundra environment. Yet, a lack of population density estimates across the North is hindering effective conservation action. The CMH has implications for the viability of peripheral populations, and the links between population fluctuations, potential bottlenecks, and genetic diversity need to be determined to contribute to species' conservation. Using noninvasive genetic sampling from 2012 to 2014 and autosomal DNA genotyping (via microsatellites), we estimated bear density using a spatial capture–recapture framework and analyzed genetic diversity using observed heterozygosity (Ho), allelic richness (AR), and expected heterozygosity (He). We compared our findings to other studies that used comparable methodologies on grizzly bears and a related species (black bears; Ursus americanus). We found densities of grizzly bears that were low for the species but characteristic for the region (5.9 ± 0.4 bears/1000 km2), but with high Ho (0.81 ± 0.05), AR (7 ± 0.78), and He (0.71 ± 0.03), despite a signal of recent bottlenecks. In both species, peripherality was not correlated with Ho but was negatively correlated with density. We suggest that the apparent growth of this expanding population of grizzlies offsets the negative impacts of recent bottlenecks on Ho. Indigenous knowledge provides historical context (on the order of centuries, e.g., arctic large mammal fluctuations, grizzly bear bottlenecks) for the current bear population dynamics (on the order of decades, e.g., climate change, northern grizzly bear expansion). [ABSTRACT FROM AUTHOR]

Recent genomic analyses have provided substantial evidence for past periods of gene flow from polar bears (Ursus maritimus) into Alaskan brown bears (Ursus arctos), with some analyses suggesting a link between climate change and genomic introgression. However, because it has mainly been possible to sample bears from the present day, the timing, frequency, and evolutionary significance of this admixture remains unknown. Here, we analyze genomic DNA from three additional and geographically distinct brown bear populations, including two that lived temporally close to the peak of the last ice age. We find evidence of admixture in all three populations, suggesting that admixture between these species has been common in their recent evolutionary history. In addition, analyses of ten fossil bears from the now-extinct Irish population indicate that admixture peaked during the last ice age, whereas brown bear and polar bear ranges overlapped. Following this peak, the proportion of polar bear ancestry in Irish brown bears declined rapidly until their extinction. Our results support a model in which ice age climate change created geographically widespread conditions conducive to admixture between polar bears and brown bears, as is again occurring today. We postulate that this model will be informative for many admixing species pairs impacted by climate change. Our results highlight the power of paleogenomics to reveal patterns of evolutionary change that are otherwise masked in contemporary data.

The polar bear (Ursus maritimus) has become a symbol of the threat to biodiversity from climate change. Understanding polar bear evolutionary history may provide insights into apex carnivore responses and prospects during periods of extreme environmental perturbations. In recent years, genomic studies have examined bear speciation and population history, including evidence for ancient admixture between polar bears and brown bears (Ursus arctos). Here, we extend our earlier studies of a 130,000- to 115,000-y-old polar bear from the Svalbard Archipelago using a 10x coverage genome sequence and 10 new genomes of polar and brown bears from contemporary zones of overlap in northern Alaska. We demonstrate a dramatic decline in effective population size for this ancient polar bear's lineage, followed by a modest increase just before its demise. A slightly higher genetic diversity in the ancient polar bear suggests a severe genetic erosion over a prolonged bottleneck in modern polar bears. Statistical fitting of data to alternative admixture graph scenarios favors at least one ancient introgression event from brown bears into the ancestor of polar bears, possibly dating back over 150,000 y. Gene flow was likely bidirectional, but allelic transfer from brown into polar bear is the strongest detected signal, which contrasts with other published work. These findings may have implications for our understanding of climate change impacts: Polar bears, a specialist Arctic lineage, may not only have undergone severe genetic bottlenecks but also been the recipient of generalist, boreal genetic variants from brown bears during critical phases of Northern Hemisphere glacial oscillations. [ABSTRACT FROM AUTHOR]

Extinct cave bears inhabited a large part of Eurasia in a wide diversity of habitats during the Pleistocene. This study investigates via tooth wear analysis the feeding habits of 66 individuals belonging to three genetically different species located in the Urals and eastern Europe: Ursus rossicus from Kizel cave, U. kanivetz from Secrets cave, and U. ingressus from Shiriaevo 1 cave. For the microwear analysis, the three species were compared with a reference collection of extant ursids. The dietary space of U. kanivetz does not match any of the extant species' spaces. U. rossicus and U. ingressus tended towards some of the extant species' measurements without any overlapping. For all three sites, the same microwear pattern was identified for all age groups (juvenile, prime, and old adult), meaning no differences related to ontogeny were found. The extinct species presented a larger number of coarse scratches compared to extant species, pointing to a preference for abrasive food items like dry grass or shrubs typical of the mammoth steppe biome during the cold season. These results indicate a niche partitioning between U. rossicus and U. kanivetz that co-existed in the same area, and in this way they avoiding competition. [ABSTRACT FROM AUTHOR]

Abstract Foraging niche variation within a species can contribute to the maintenance of phenotypic diversity. The multiniche model posits that phenotypes occupying different niches can contribute to the maintenance of balanced polymorphisms. Using coastal populations of black bears (Ursus americanus kermodei) from British Columbia, Canada, we examined potential foraging niche divergence between phenotypes (black and white “Spirit” coat color) and between genotypes (black‐coated homozygote and heterozygous). We applied the Bayesian multivariate models, with biotracers of diet (δ13C and δ15N) together comprising the response variable, to draw inference about foraging niche variation. Variance–covariance matrices from multivariate linear mixed‐effect models were visualized as the Bayesian standard ellipses in δ13C and δ15N isotopic space to assess potential seasonal and annual niche variation between phenotypes and genotypes. We did not detect a difference in annual isotopic foraging niche area in comparisons between genotypes or phenotypes. Consistent with previous field experimental and isotopic analyses, however, we found that white phenotype Spirit bears were modestly more enriched in δ15N during the fall foraging season, though with our modest sample sizes these results were not significant. Although also not statistically significant, variation in isotopic niches between genotypes revealed that heterozygotes were moderately more enriched in δ13C along hair segments grown during fall foraging compared with black‐coated homozygotes. To the extent to which the pattern of elevated δ15N and δ13C may signal the consumption of salmon (Oncorhynchus spp.), as well as the influence of salmon consumption on reproductive fitness, these results suggest that black‐coated heterozygotes could have a minor selective advantage in the fall compared with black‐coated homozygotes. More broadly, our multivariate approach, coupled with knowledge of genetic variation underlying a polymorphic trait, provides new insight into the potential role of a multiniche mechanism in maintaining this rare morph of conservation priority in Canada's Great Bear Rainforest and could offer new understanding into polymorphisms in other systems.

The American black bear (Ursus americanus) was long thought to be solitary and its social organization has not been well described. Here, we present new data on black bear social structure. The objectives of the study were to make detailed observations of the behavior of wild black bears to determine their social interactions and structure. We tested whether black bears interacted socially beyond mating and competing for resources, if black bears tracked relationships and interacted regularly even when resources were not limited, and whether the social structure of a population of black bears was based on a matrilinear hierarchy. We collected data by direct observation of bears from 1993 to 2014. Observations of 1210 social interactions at a provisioning site indicated that females compete and form matrilinear hierarchies. Dominant bears established a hierarchy for food, control of space, and control of younger bears. Post interaction scent marking took place, which suggested that dominant females were conditioning subordinates to their scent marks. Affiliative behavior occurred between related and unrelated bears and helped to establish the social structure of the bear community. Based on our data, human–bear conflicts can be reduced by behavioral modifications by humans when they encounter bears. Knowledge of bear behavior and the matrilinear hierarchy provide a basis for non‐lethal management of bears that find themselves in a bear–human conflict situation. [ABSTRACT FROM AUTHOR]

Contemporary climate change is predicted to expose some species to altered predation regimes. Losses of Arctic sea ice are causing polar bears to increasingly forage on colonial seaduck eggs in lieu of ice-based hunting of marine mammals. Although polar bear predation of bird eggs has now been widely documented, it is unclear whether this change in predator behavior is having population-level consequences for Arctic breeding birds. In this study, we tested whether changes in the number of common eider nests on 76 islands in Hudson Strait, Canada, were related to variation in polar bear presence. We found that polar bear sign detected during eider breeding surveys was strongly correlated with spatial patterns of polar bears observed during aerial surveys. However, changes in eider nest count did not appear to be clearly related to polar bear sign at either the island scale or the island-cluster scale. This results of this study, therefore, suggest that the spatial overlap between eiders and polar bears varies across the landscape, but patterns of polar bear spatial variation do not seem to have driven large-scale redistribution of nesting common eiders.

Polar bears are an arctic, marine adapted species that is closely related to brown bears. Genome analyses have shown that polar bears are distinct and genetically homogeneous in comparison to brown bears. However, these analyses have also revealed a remarkable episode of polar bear gene flow into the population of brown bears that colonized the Admiralty, Baranof and Chichagof islands (ABC islands) of Alaska. Here, we present an analysis of data from a large panel of polar bear and brown bear genomes that includes brown bears from the ABC islands, the Alaskan mainland and Europe. Our results provide clear evidence that gene flow between the two species had a geographically wide impact, with polar bear DNA found within the genomes of brown bears living both on the ABC islands and in the Alaskan mainland. Intriguingly, while brown bear genomes contain up to 8.8% polar bear ancestry, polar bear genomes appear to be devoid of brown bear ancestry, suggesting the presence of a barrier to gene flow in that direction.

Foraging niche variation within a species can contribute to the maintenance of phenotypic diversity. The multiniche model posits that phenotypes occupying different niches can contribute to the maintenance of balanced polymorphisms. Using coastal populations of black bears (Ursus americanus kermodei) from British Columbia, Canada, we examined potential foraging niche divergence between phenotypes (black and white "Spirit" coat color) and between genotypes (black‐coated homozygote and heterozygous). We applied the Bayesian multivariate models, with biotracers of diet (δ13C and δ15N) together comprising the response variable, to draw inference about foraging niche variation. Variance–covariance matrices from multivariate linear mixed‐effect models were visualized as the Bayesian standard ellipses in δ13C and δ15N isotopic space to assess potential seasonal and annual niche variation between phenotypes and genotypes. We did not detect a difference in annual isotopic foraging niche area in comparisons between genotypes or phenotypes. Consistent with previous field experimental and isotopic analyses, however, we found that white phenotype Spirit bears were modestly more enriched in δ15N during the fall foraging season, though with our modest sample sizes these results were not significant. Although also not statistically significant, variation in isotopic niches between genotypes revealed that heterozygotes were moderately more enriched in δ13C along hair segments grown during fall foraging compared with black‐coated homozygotes. To the extent to which the pattern of elevated δ15N and δ13C may signal the consumption of salmon (Oncorhynchus spp.), as well as the influence of salmon consumption on reproductive fitness, these results suggest that black‐coated heterozygotes could have a minor selective advantage in the fall compared with black‐coated homozygotes. More broadly, our multivariate approach, coupled with knowledge of genetic variation underlying a polymorphic trait, provides new insight into the potential role of a multiniche mechanism in maintaining this rare morph of conservation priority in Canada's Great Bear Rainforest and could offer new understanding into polymorphisms in other systems. [ABSTRACT FROM AUTHOR]

Hibernating bears survive up to 6 months without feeding while yet maintaining metabolic homeostasis. We previously reported expression changes in energy metabolism-related genes in the liver of hibernating Japanese black bears. The present study examined the role of microRNAs in the regulation of hepatic gene expression during hibernation. The quantitative analyses revealed significant increases in the expression of 4 microRNAs (miR-221-3p, miR-222-3p, miR-455-3p, and miR-195a-5p) and decreases of 2 microRNAs (miR-122-5p and miR-7a-1-5p) during hibernation. RNA sequencing and in silico target prediction regarding 3 upregulated microRNAs (miR-221-3p, miR-222-3p and miR-455-3p) found 13 target mRNAs with significantly decreased expression during hibernation. The transfection of microRNA mimics into cells showed that miR-222 and miR-455 reduced solute carrier family 16 member 4 (SLC16A4) and fatty acid synthase (FASN) mRNA expression, respectively. Our results suggest that the increased levels of hepatic miRNA during hibernation (miR-222-3p and miR-455-3p) negatively regulate the expression of targeted genes predicted to be involved in the transport of energy source and de novo fatty acid synthesis, is consistent with a regulatory role of these miRNAs in energy metabolism in hibernating black bears. [ABSTRACT FROM AUTHOR]

a loose/broken stalagmite containing small fragments of cemented bones were collected from the Postojna Cave to investigate whether deoxyribonucleic acid (DNA) can be determined. The study is complemented by the Fourier-transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) analysis in order to determine the alteration of the bones and to test whether this analysis can be used as an indicator of possible DNA preservation. In addition, geochemical analyses were conducted in order to determine whether the associated flowstone/stalagmite is suitable for elucidating the timing of bone thanatocoenosis and further palaeoenvironmental analyses. The organic matter (collagen) is poorly preserved. However, we succeeded in amplifying a 94 bp long fragment of the cytochrome b (Cyt b) gene of mitochondrial DNA (mtDNA) in polymerase chain reaction (PCR) for one sample, and in sequencing the amto that of the Cyt b of the cave bear (Ursus deningeri or Ursus spelaeus sensu lato). The uranium-thorium dating of the speleothem covering the bones revealed its thanatocoenosis occurred prior to 55 ka, most likely in the late marine isotope stage 4 or early marine isotope stage 3. High porosity and recrystallisation of the flowstone/stalagmite at this part of the cave prevent high-resolution palaeoclimatic interpretation; however, low-resolution stable isotope geochemistry suggests a steppe-like environment during the subsequent growth of the speleothem.

Abstract 1. Preserving genetic and phenotypic diversity can help safeguard not only biodiversity but also cultural and economic values. 2. Here, we present data that emerged from Indigenous‐led research at the intersection of evolution and ecology to support conservation planning of a culturally salient, economically valuable, and rare phenotypic variant. We addressed three conservation objectives for the white‐phased ‘Spirit bear’ polymorphism, a rare and endemic white‐coated phenotype of black bear (Ursus americanus) in Kitasoo/Xai'xais and Gitga'at Territories and beyond in coastal British Columbia, Canada. First, we used non‐invasively collected hair samples (n = 385 bears over ∼18,000 km2) to assess the spatial variation in the frequency of the allele that controls the white‐coloured morph (mc1r). Second, we compared our observed allele frequencies at mc1r with those expected under Hardy–Weinberg equilibrium. Finally, we examined how well current protected areas in the region aligned with spatial hotspots of Spirit bear alleles. 3. We found that landscape‐level allele frequency was lower than previously reported. For example our systematic sampling estimated a frequency of 0.25 (95% CI [0.13, 0.41]) on Gribbell Island compared with the previously reported estimate of 0.56. Also, in contrast with previous reports, we failed to detect a statistically significant departure from Hardy–Weinberg equilibrium at mc1r, which calls into question the previously posited role of homozygote gene flow, heterozygote disadvantage, and positive assortative mating in the maintenance of this polymorphism. Finally, we found a discrepancy between the placement of protected areas and the 90th percentile hotspots (upper 10% of all estimated values) of Spirit bear alleles, with ∼50% of hotspots falling outside of protected areas. 4. These results provide new insight into hypotheses related to the maintenance of this rare polymorphism, and directly relevant information to support evidence‐based opportunities for Indigenous Nations of the area to attend to gaps in conservation planning.

Reliable methods to measure stress-related glucocorticoid responses in free-ranging animals are important for wildlife management and conservation. Such methods are also paramount for our ability to improve our knowledge of the ecological consequences of physiological processes. The brownbear (Ursus arctos) is a large carnivore of ecological and cultural importance and is important for management. Here, we provide a physiological validation for an enzyme immunoassay (EIA) to quantify glucocorticoid metabolites in brown bear feces. We also provide an evaluationof the effects of sample exposure to ambient temperature on measured fecal glucocorticoid metabolite (fGCM) concentrations. We evaluated three EIA systems: a cortisol assay, an 11- oxoetiocholanolone assay, and an 11b-hydroxyetiocholanolone assay. Of these, the cortisol assay provided the best discrimination between peak fGCM concentrations detected 1–4 d after injections of synthetic adrenocorticotrophic hormone and preinjection baseline concentrations in four individual brown bears. The time of exposure to ambient temperature had substantial but variable effects on measured fGCM concentrations, including variation both between samples from the same individual and among samples from different bears. We propose that the validated EIA system for measuring fGCM concentrations in the brown bear could be a useful noninvasive method to monitor stress in this species. However, we highlight that this method requires that fecal samples be frozen immediately after defecation, which could be a limitation in many field situations. [ABSTRACT FROM AUTHOR]

Loose bone fragments coated with calcite precipitate including a loose/broken stalagmite containing small fragments of cemented bones were collected from the Postojna Cave to investigate whether deoxyribonucleic acid (DNA) can be determined. The study is complemented by the Fourier-transform infrared spectroscopy - attenuated total reflectance (FTIR-ATR) analysis in order to determine the alteration of the bones and to test whether this analysis can be used as an indicator of possible DNA preservation. In addition, geochemical analyses were conducted in order to determine whether the associated flowstone/stalagmite is suitable for elucidating the timing of bone thanatocoenosis and further palaeoenvironmental analyses. The organic matter (collagen) is poorly preserved. However, we succeeded in amplifying a 94 bp long fragment of the cytochrome b (Cyt b) gene of mitochondrial DNA (mtDNA) in polymerase chain reaction (PCR) for one sample, and in sequencing the amplified products. The 70 bp long sequence obtained corresponds to that of the Cyt b of the cave bear (Ursus deningeri or Ursus spelaeus sensu lato). The uranium-thorium dating of the speleothem covering the bones revealed its thanatocoenosis occurred prior to 55 ka, most likely in the late marine isotope stage 4 or early marine isotope stage 3. High porosity and recrystallisation of the flowstone/stalagmite at this part of the cave prevent high-resolution palaeoclimatic interpretation; however, low-resolution stable isotope geochemistry suggests a steppe-like environment during the subsequent growth of the speleothem. [ABSTRACT FROM AUTHOR]

Aim: Assessing the relevance of niche evolution in the diversification patterns and geographical distribution of species driven by climate remains a challenge. We apply an integrative approach to evaluate the role of the environment on the phylogeography of bear species, incorporating fossil data to characterize the changes in the ecological niche through time. We evaluate our approach with the four extant species of bears within Ursus, the best represented taxon in the fossil record of the family Ursidae. Location: Eurasia and North America. Taxa: Asian black bear, Ursus thibetanus; American black bear, U. americanus; Brown bear, U. arctos; and Polar bear, U. maritimus. Methods: We built a genetic and a geographical database from all published mitochondrial DNA sequences and of species occurrence records. We defined the most significant climatic variables based on each species ecological realm using correlation matrices, and characterized the ecological niches and existing environmental conditions with ellipsoid models. We inferred their current and Last Glacial Maximum (LGM) ecological niche modellings (ENMs) and compared the results with the fossil record. We estimated the times of divergence (d‐loop sequences) of lineages and applied a phyloclimatespace approach to discern the phylogeographical patterns along each species' ecological space. Results: Ecological niche modelling showed wider niches for U. thibetanus and U. americanus encompassing higher temperature and precipitation, while U. arctos and U. maritimus showed an opposite pattern. LGM models were consistent with the fossil record, predicting 55%–89% of the fossil occurrences (within their suitability areas). The phyloclimatespace revealed different degrees of environmental signal in the lineages' phylogeographical patterns and ecological trajectories associated with LGM climatic conditions. Results indicated habitat tracking and ecological expansion since the LGM towards more extreme precipitation and temperature conditions for three species, except U. maritimus that showed ecological niche reduction. Main Conclusions: Incorporating fossil information from the LGM improved our characterization and interpretation of ecological models, by enabling definition of the limits of the climatic conditions explored by the species in the past. Our approach also provided insights about the existing set of environmental conditions shaping the ecological niche divergence of Ursus bears. We were able to depict key features of the lineages' evolutionary history, ecology and distribution, revealing the dynamics of niche occupation and the environmental signal on the phylogeographical patterns of Ursus. [ABSTRACT FROM AUTHOR]

This study is focused on cave bears from the Grotta del Bandito (Cuneo Province, Piedmont Region, Northern Italy), especially their teeth. The morphodynamic analyses have been elaborated and compared with other cave bears from Northern Italy, and other cave bear taxa from particular European sites. The Grotta del Bandito bears are similar in size to other cave bears from Italy, and no differences were observed with the other cave bear species or subspecies (e.g. U. ingressus, U. s. ladinicus, U. s. eremus). Thus their inclusion in the U. gr. spelaeus is the most appropriate classification, and they show a simpler dental surface than the "modern" cave bears (i.e. ingressus). The question of whether a single species of spelaeus lived in North Italy, is also introduced. In fact, the differences in size are probably the result of population variability, and no clear evidence of other spelaeoid species and/or subspecies, i.e. ingressus, s. ladinicus and s. eremus, was discovered. [ABSTRACT FROM AUTHOR]

Lead (Pb) exposure is associated with adverse health effects in both humans and wildlife. Blood lead levels (BLL) of sentinel wildlife species can be used to monitor environmental lead exposure and ecosystem health. BLL analyzers, such as the LeadCare®, are validated for use in humans, assessed for use in some avian species and cattle, and are increasingly being used on wildlife to monitor lead exposure. The LeadCare® analyzers use a technique called anodic stripping voltammetry (ASV). Species-specific conversion equations have been proposed to approximate the levels found with gold standard measuring methods such as inductively coupled plasma mass spectrometry (ICP-MS) because the ASV method has been shown to underestimate BLL in some species. In this study we assessed the LeadCare® Plus (LCP) for use on Scandinavian brown bears (Ursus arctos). LCP measurements were correlated with ICP-MS with a Bland-Altman analyzed bias of 16.3–22.5%, showing a consistent overestimation of BLL analyzed with LCP. Based on this analysis we provide conversion equations for calculating ICP-MS BLL based on the LCP results in Scandinavian brown bears. Our study shows that the LeadCare® Plus can be used for monitoring of lead exposure by approximating gold standard levels using conversion equations. This enables comparison with other gold standard measured BLL within the observed range of this study (38.20–174.00 μg/L). Our study also found that Scandinavian brown bears are highly exposed to environmental lead.

This document discusses the interaction between black bears and beekeeping in Florida. It highlights the areas in Florida where black bear populations are concentrated and the frequency of bear depredations on apiaries. The manuscript emphasizes prevention as the best defense against bear attacks on beehives, recommending the use of platforms and electric fences as effective deterrents.

Abstract Morphometric and morphotypic variability of the cave bear upper incisors from two different geographic regions (Caucasus and Urals), different stratigraphic periods (middle and late Pleistocene), and bearing different mitochondrial haplogroups (kudarensis and ingressus) was studied. The specific diet of the cave bears, i.e. hard vegetables, led to noticeable differences between their incisors and the incisors of the brown bear (Ursus arctos). It was found that the upper incisors of the Caucasian cave bears from different stratigraphic periods demonstrate consistent development of their morphology. The late Pleistocene cave bears from the Urals show a greater similarity to the Caucasian cave bears from earlier periods than with the cave bears from later periods. Our results suggest that the incisor morphology has evolved independently in the Caucasian and Ural cave bears as they belong to different phylogenetic lineages and display different ways of adaptation to local environmental conditions. [ABSTRACT FROM AUTHOR]

Resource waves—spatial variation in resource phenology that extends feeding opportunities for mobile consumers—can affect the behaviour and productivity of recipient populations. Interspecific diversity among Pacific salmon species (Oncorhynchus spp.) creates staggered spawning events across space and time, thereby prolonging availability to terrestrial wildlife.We sought to understand how such variation might influence consumption by terrestrial predators compared with resource abundance and intra‐ and interspecific competition.Using stable isotope analysis, we investigated how the proportion of salmon in the annual diet of male black bears (Ursus americanus; n = 405) varies with species diversity and density of spawning salmon biomass, while also accounting for competition with sympatric black and grizzly bears (U. arctos horribilis), in coastal British Columbia, Canada.We found that the proportion of salmon in the annual diet of black bears was ≈40% higher in the absence of grizzly bears, but detected little effect of relative black bear density and salmon biomass density. Rather, salmon diversity had the largest positive effect on consumption. On average, increasing diversity from one salmon species to ~four (with equal biomass contributions) approximately triples the proportion of salmon in diet.Given the importance of salmon to bear life histories, this work provides early empirical support for how resource waves may increase the productivity of consumers at population and landscape scales. Accordingly, terrestrial wildlife management might consider maintaining not only salmon abundance but also diversity. The species diversity of spawning salmon present in watersheds, not abundance, predicts the proportion of salmon in the annual diet of coastal black bears (Ursus americanus). Additionally, grizzly bear (Ursus arctos) presence reduces salmon consumption by ~40%, no matter the level of salmon diversity available. [ABSTRACT FROM AUTHOR]

Abstract This study presents a new database of dental microwear features for extant bear species, which is used to interpret palaeodiet in brown bear (Ursus arctos) from the late Middle Pleistocene site of Grays Thurrock, U.K. Applying light stereomicroscopy techniques in dental microwear analysis, we highlight, for the first time, that the talonid area of the first lower molar (m1) in extant ursids is most effective in the differentiation of dietary ecospaces. Extant bear species can be separated into different parts of a dietary ecospace revealing microwear features that mirror their dietary preferences. Of particular note is the differentation of ecospaces within modern brown bear populations from different geographical regions and the potential for identifying seasonal variation in diet. The results demonstrate that the diet of thelate Middle Pleistocene brown bear from the interglacial site of Grays Thurrock was closely comparable to that of the modern U. arctos from northern Europe, the American black bear (Ursus americanus), and the sun bear (Helarctos malayanus). This suggests the dietary importance of fibrous food, as well as soft fruits and invertebrates and a small vertebrate component. This finding is in agreement with climatic conditions and habitats inferred for the MIS 9 interglacial. The creation and testing of a dental microwear database for all modern bear species provides a foundation for subsequent application to other extinct Pleistocene bear populations. Highlights • New and comprehensive dental microwear database for modern Ursidae is presented. • Talonid area of m1 is most effective in the differentiation of ursid ecospaces. • Dietary ecospaces were established for the extant species. • Dietary differences can be traced also in brown bears from different latitudes. • The ecospace and palaeodietary niche were established for the fossil Grays bears, UK. [ABSTRACT FROM AUTHOR]

Spatially explicit capture–recapture methods do not assume that animals have equal access to sampling devices (e.g., detectors), which allows for gaps in the sampling extent and nonuniform (e.g., clustered) sampling designs. However, the performance (i.e., relative root mean squared error [RRMSE], confidence interval coverage, relative bias and relative standard error) of clustered detector arrays has not been thoroughly evaluated. I used simulations to evaluate the performance of various detector and cluster spacings, cluster configurations (i.e., number of detectors arranged in a square grid), sampling extents and number of sampling occasions for estimating population density, the relationship between detection rate and distance to a detector from the animal's center of activity (σ) and base detection rates, using American black bears (Ursus americanus) as a case study. My simulations indicated that a wide range of detector configurations can provide reliable estimates if spacing between detectors in clusters is ≥1σ and ≤3σ. A number of cluster configurations and occasion lengths produced estimates that were unbiased, resulted in good spatial coverage, and were relatively precise. Moreover, increasing the duration of sampling, establishing large study areas, increasing detection rates and spacing clusters so that cross‐cluster sampling of individuals can occur could help ameliorate deficiencies in the detector layout. These results have application for a wide array of species and sampling methods (e.g., DNA sampling, camera trapping, mark‐resight and search‐encounter) and suggest that clustered sampling can significantly reduce the effort necessary to provide reliable estimates of population density across large spatial extents that previously would have been infeasible with nonclustered sampling designs. Simulations were performed to evaluate clustered sampling designs for estimating population density using spatially explicit capture‐recapture methods. Clustered sampling designs were reliable and robust for a wide array of detector spacings, cluster configurations, and occasion lengths. These results are applicable to a wide range of species and sampling methods and indicate clustered sampling methods can be efficacious over large sampling extents. [ABSTRACT FROM AUTHOR]

Abstract The Villafranchian ursids of Greece are scanty, represented by a few isolated teeth and bones. During our last field campaigns in the Mygdonia Basin (Macedonia, Greece) we discovered an almost complete cranium, as well as some cranial, dental and postcranial remains, which are presented in this article. The new material originates from the locality Tsiotra Vryssi (TSR), dated to the late Villafranchian (1.8–1.2 Ma). The specimens are described and compared with ursids from various European localities; their morphological characters and dimensions place it with Ursus etruscus Cuvier, 1823, while the dental features are most similar to the specimens from Pietrafitta (Italy). The TSR cranium was CT-scanned in order to create a 3D virtual model and study its internal anatomy. Its observed endocranial traits exhibit primitive conditions, confirming the basal position of U. etruscus among the Pleistocene European ursids. Most of these features are shared with U. arctos and clearly differ from U. deningeri and U. spelaeus. Finally, we provide a revision of the known Greek material of U. etruscus and the biostratigraphic distribution of the Miocene–Pleistocene ursids of Greece. The earliest secure appearance of Ursus etruscus in Greece is found in the locality Dafnero 1 (Western Macedonia), dated to the end of the middle Villafranchian at ∼2.0 Ma, whereas its probable last occurrence is known from the locality Apollonia 1 of the Mygdonia Basin, dated to the latest Villafranchian at ∼1.2 Ma. [ABSTRACT FROM AUTHOR]

Transcriptome analysis of polar bear (Ursus maritimus) tissues identified sequences with similarity to Porcine Endogenous Retroviruses (PERV). Based on these sequences, four proviral copies and 15 solo long terminal repeats (LTRs) of a newly described endogenous retrovirus were characterized from the polar bear draft genome sequence. Closely related sequences were identified by PCR analysis of brown bear (Ursus arctos) and black bear (Ursus americanus) but were absent in non-Ursinae bear species. The virus was therefore designated UrsusERV. Two distinct groups of LTRs were observed including a recombinant ERV that contained one LTR belonging to each group indicating that genomic invasions by at least two UrsusERV variants have recently occurred. Age estimates based on proviral LTR divergence and conservation of integration sites among ursids suggest the viral group is only a few million years old. The youngest provirus was polar bear specific, had intact open reading frames (ORFs) and could potentially encode functional proteins. Phylogenetic analyses of UrsusERV consensus protein sequences suggest that it is part of a pig, gibbon and koala retrovirus clade. The young age estimates and lineage specificity of the virus suggests UrsusERV is a recent cross species transmission from an unknown reservoir and places the viral group among the youngest of ERVs identified in mammals.

Vitamin A is a fat-soluble vitamin required for many physiological functions. It is known that polar bears (Ursus maritimus) store a large amount of vitamin A within hepatic stellate cells (HSCs). However, the molecular mechanisms for high-capacity storage of vitamin A by polar bear HSCs are unknown. We biochemically and histochemically analyzed lecithin:retinol acyltransferase (LRAT), an enzyme responsible for conversion of retinol to its storage form, retinylesters, in the liver. Surprisingly, LRAT activities of the liver microsome fractions from polar bears weighing 100-500 kg were considerably lower than those obtained from rats (Rattus norvegicus). Although there is a possibility that the quality of polar bear liver specimens was reduced during transport, intrinsic LRAT activity of polar bears might actually be lower than those of other mammals. Fluorescent immunohistochemistry revealed that LRAT and cellular retinol-binding protein (CRBP) I were well co-localized within the liver lobules of polar bears. Taking into account that retinol bound to CRBP I is prevented from degradation and becomes a good substrate of LRAT, we hypothesized that CRBP I effectively conveys retinol to the LRAT, thereby circumventing the low enzymatic activity of LRAT in polar bear livers. As the top predator in the Arctic, polar bears have access to large amounts of vitamin A via the food web. We suggest that polar bears acquired an efficient mechanism of esterification of vitamin A within the liver during the course of their evolution. [ABSTRACT FROM AUTHOR]

Behavioral differences within a population can allow use of a greater range of resources among individuals. The brown bear (Ursus arctos) is a generalist omnivore that occupies diverse habitats and displays considerable plasticity in food use. We evaluated whether brown bear foraging that resulted in deviations from a proposed optimal diet influenced body condition and, in turn, denning duration in Lake Clark National Park and Preserve, Alaska. To assess assimilated diet, we used sectioned guard hair samples (n = 23) collected in autumn to determine stable carbon and nitrogen isotope ratios. To index proportional contributions of meat and vegetation to assimilated diets, we compared the carbon (δ13C) and nitrogen (δ15N) values of hair samples with the values identified for major food categories. We then compared percentage body fat and body mass in relation to the proportion of assimilated meat in the diet using linear models. We also examined the influence of autumn percentage body fat and mass on denning duration. Percentage body fat was not influenced by the proportion of assimilated meat in the diet. Additionally, percentage body fat and body mass did not influence denning duration. However, body mass of bears assimilating proportionately more meat was greater than bears assimilating less meat. Our results provide support for previous findings that larger bears consume higher amounts of protein to maintain their body size and therefore forage further from the proposed optimal diet. Additionally, our results demonstrate that individuals can achieve similar biological outcomes (e.g., percentage body fat) despite variable foraging strategies, suggesting that individuals within generalist populations may confer an adaptive advantage through behavioral plasticity. [ABSTRACT FROM AUTHOR]