| optimization of conditions for long-term prefreezing storage of brown bear sperm before cryopreservation. | brown bear ejaculates are usually collected in field conditions and may need to be shipped to a laboratory for the application of reproductive biotechnologies before cryopreservation. the aim of this study was to extend the prefreezing step to 48 hours (1 hour vs. long-term storage [ls] to 24 and 48 hours) to enable the sample to be transported. the effects of storage temperature (experiment 1), glycerol concentration (experiment 2), and dilution rate (experiment 3) on sperm were evaluated. elec ... | 2015 | 26234462 |
| a comparison of grizzly bear demographic parameters estimated from non-spatial and spatial open population capture-recapture models. | capture-recapture studies are frequently used to monitor the status and trends of wildlife populations. detection histories from individual animals are used to estimate probability of detection and abundance or density. the accuracy of abundance and density estimates depends on the ability to model factors affecting detection probability. non-spatial capture-recapture models have recently evolved into spatial capture-recapture models that directly include the effect of distances between an anima ... | 2015 | 26230262 |
| hydrogen sulfide and nitric oxide metabolites in the blood of free-ranging brown bears and their potential roles in hibernation. | during winter hibernation, brown bears (ursus arctos) lie in dens for half a year without eating while their basal metabolism is largely suppressed. to understand the underlying mechanisms of metabolic depression in hibernation, we measured type and content of blood metabolites of two ubiquitous inhibitors of mitochondrial respiration, hydrogen sulfide (h2s) and nitric oxide (no), in winter-hibernating and summer-active free-ranging scandinavian brown bears. we found that levels of sulfide metab ... | 2014 | 24909614 |
| grizzly bear hair reveals toxic exposure to mercury through salmon consumption. | mercury obtained from the diet accumulates in mammalian hair as it grows thus preserving a record of mercury intake over the growth period of a given hair segment. we adapted a microanalysis approach, using laser ablation inductively coupled plasma mass spectrometry, to characterize temporal changes in mercury exposure and uptake in wild and captive grizzly bears. captive grizzlies fed diets containing known and varied amounts of mercury provided data to allow prediction of hg ingestion rates in ... | 2014 | 24904971 |
| fellatio in captive brown bears: evidence of long-term effects of suckling deprivation? | sexually stimulating behaviors that are not linked to reproduction are rare among non-human (especially non-primate) mammals. such behaviors may have a function in the hierarchy of social species. in solitary species, such behaviors are more enigmatic, and possibly indicative of something abnormal. here, we report on a case of two male brown bears, raised in captivity since being orphaned as cubs, which engaged in recurrent fellatio multiple times per day until at least 10 years old. the roles o ... | 2014 | 24899532 |
| study yields “genghis khan” of brown bears, new understanding of brown and polar bear evolution. | | 2014 | 24860012 |
| evidence of rapid change in genetic structure and diversity during range expansion in a recovering large terrestrial carnivore. | recovery of natural populations occurs often with simultaneous or subsequent range expansions. according to population genetic theory, genetic structuring emerges at the expansion front together with decreasing genetic diversity, owing to multiple founder events. thereupon, as the expansion proceeds and connectivity among populations is established, homogenization and a resurgence of genetic diversity are to be expected. few studies have used a fine temporal scale combined with genetic sampling ... | 2015 | 25904665 |
| a "clearcut" case? brown bear selection of coarse woody debris and carpenter ants on clearcuts. | forest management alters habitat characteristics, resulting in various effects among and within species. it is crucial to understand how habitat alteration through forest management (e.g. clearcutting) affects animal populations, particularly with unknown future conditions (e.g. climate change). in sweden, brown bears (ursus arctos) forage on carpenter ants (camponotus herculeanus) during summer, and may select for this food source within clearcuts. to assess carpenter ant occurrence and brown b ... | 2015 | 26190890 |
| population genomics reveal recent speciation and rapid evolutionary adaptation in polar bears. | polar bears are uniquely adapted to life in the high arctic and have undergone drastic physiological changes in response to arctic climates and a hyper-lipid diet of primarily marine mammal prey. we analyzed 89 complete genomes of polar bear and brown bear using population genomic modeling and show that the species diverged only 479-343 thousand years bp. we find that genes on the polar bear lineage have been under stronger positive selection than in brown bears; nine of the top 16 genes under s ... | 2014 | 24813606 |
| oxygen supplementation in anesthetized brown bears (ursus arctos)-how low can you go? | hypoxemia is anticipated during wildlife anesthesia and thus should be prevented. we evaluated the efficacy of low flow rates of supplemental oxygen for improvement of arterial oxygenation in anesthetized brown bears (ursus arctos). the study included 32 free-ranging brown bears (yearlings, subadults, and adults; body mass 12-250 kg) that were darted with medetomidine-zolazepam-tiletamine (mzt) from a helicopter in sweden. during anesthesia, oxygen was administered intranasally from portable oxy ... | 2014 | 24807187 |
| prioritizing sites for protection and restoration for grizzly bears (ursus arctos) in southwestern alberta, canada. | as the influence of human activities on natural systems continues to expand, there is a growing need to prioritize not only pristine sites for protection, but also degraded sites for restoration. we present an approach for simultaneously prioritizing sites for protection and restoration that considers landscape patterns for a threatened population of grizzly bears (ursus arctos) in southwestern alberta, canada. we considered tradeoffs between bottom-up (food resource supply) and top-down (mortal ... | 2015 | 26168055 |
| a mass burial of brown bears (ursus arctos l., 1758) from the upper pleistocene of the northern urals. | | 2015 | 26164331 |
| brown and polar bear y chromosomes reveal extensive male-biased gene flow within brother lineages. | brown and polar bears have become prominent examples in phylogeography, but previous phylogeographic studies relied largely on maternally inherited mitochondrial dna (mtdna) or were geographically restricted. the male-specific y chromosome, a natural counterpart to mtdna, has remained underexplored. although this paternally inherited chromosome is indispensable for comprehensive analyses of phylogeographic patterns, technical difficulties and low variability have hampered its application in most ... | 2014 | 24667925 |
| effect of active cooling and α-2 adrenoceptor antagonism on core temperature in anesthetized brown bears (ursus arctos). | hyperthermia is a common complication during anesthesia of bears, and it can be life threatening. the objective of this study was to evaluate the effectiveness of active cooling on core body temperature for treatment of hyperthermia in anesthetized brown bears (ursus arctos). in addition, body temperature after reversal with atipamezole was also evaluated. twenty-five adult and subadult brown bears were captured with a combination of zolazepam-tiletamine and xylazine or medetomidine. a core temp ... | 2015 | 26056880 |
| behavioural differences between single scandinavian brown bears (ursus arctos) and females with dependent young when experimentally approached by humans. | carnivore-human encounters that result in human injury present a conservation and management challenge and it is therefore important to understand under what conditions such incidents occur. females with cubs are often involved when humans are injured by brown bears ursus arctos. in scandinavia, this is particularly true for unarmed recreational forest users. our aim was to document behavioural differences between single bears and females with cubs in order to develop recommendations to minimize ... | 2015 | 25830333 |
| major decline in marine and terrestrial animal consumption by brown bears (ursus arctos). | human activities have had the strongest impacts on natural ecosystems since the last glacial period, including the alteration of interspecific relationships such as food webs. in this paper, we present a historical record of major alterations of trophic structure by revealing millennium-scale dietary shifts of brown bears (ursus arctos) on the hokkaido islands, japan, using carbon, nitrogen, and sulfur stable isotope analysis. dietary analysis of brown bears revealed that salmon consumption by b ... | 2015 | 25776994 |
| litter loss triggers estrus in a nonsocial seasonal breeder. | sexually selected infanticide (ssi) is often presumed to be rare among seasonal breeders, because it would require a near immediate return to estrus after the loss of an entire litter during the mating season. we evaluated changes in reproductive strategies and the reproductive fate of females that experienced litter loss during the mating season in a seasonal breeder with strong evidence for ssi, the brown bear. first, we used a long-term demographic dataset (1986-2011) to document that a large ... | 2014 | 24558586 |
| polar bears exhibit genome-wide signatures of bioenergetic adaptation to life in the arctic environment. | polar bears (ursus maritimus) face extremely cold temperatures and periods of fasting, which might result in more severe energetic challenges than those experienced by their sister species, the brown bear (u. arctos). we have examined the mitochondrial and nuclear genomes of polar and brown bears to investigate whether polar bears demonstrate lineage-specific signals of molecular adaptation in genes associated with cellular respiration/energy production. we observed increased evolutionary rates ... | 2014 | 24504087 |
| seasonal changes in isoform composition of giant proteins of thick and thin filaments and titin (connectin) phosphorylation level in striated muscles of bears (ursidae, mammalia). | seasonal changes in the isoform composition of thick and thin filament proteins (titin, myosin heavy chains (myhcs), nebulin), as well as in the phosphorylation level of titin in striated muscles of brown bear (ursus arctos) and hibernating himalayan black bear (ursus thibetanus ussuricus) were studied. we found that the changes that lead to skeletal muscle atrophy in bears during hibernation are not accompanied by a decrease in the content of nebulin and intact titin-1 (t1) isoforms. however, a ... | 2015 | 25761688 |
| application of brown bear (ursus arctos) records for retrospective assessment of mercury. | because mercury (hg) is released into the atmosphere, wildlife living in habitats located far from point sources of metal may still be at risk. mercury accumulation, previously considered a risk for aquatic ecosystems, is also found in many wildlife terrestrial species. the aim of the present study was to examine total hg concentrations in the brown bear (ursus arctos) by measurement of metal in hair from museum collections in iran. another objective of this investigation was to characterize the ... | 2015 | 25734629 |
| wolves trigger a trophic cascade to berries as alternative food for grizzly bears. | this is a forum article in response to: barber-meyer, s. (2015) trophic cascades from wolves to grizzly bears or changing abundance of bears and alternate foods? journal of animal ecology, 83, doi: 10.1111/1365-2656.12338. we used multiple data sets and study areas as well as several lines of evidence to investigate potential trophic linkages in yellowstone national park. our results suggest that a trophic cascade from wolves to elk to berry production to berry consumption by grizzly bears may n ... | 2015 | 25732407 |
| effect of season and high ambient temperature on activity levels and patterns of grizzly bears (ursus arctos). | understanding factors that influence daily and annual activity patterns of a species provides insights to challenges facing individuals, particularly when climate shifts, and thus is important in conservation. using gps collars with dual-axis motion sensors that recorded the number of switches every 5 minutes we tested the hypotheses: 1. grizzly bears (ursus arctos) increase daily activity levels and active bout lengths when they forage on berries, the major high-energy food in this ecosystem, a ... | 2015 | 25692979 |
| evaluation of the accuracy of different methods of monitoring body temperature in anesthetized brown bears (ursus arctos). | there is some evidence that the handheld rectal thermometer does not accurately measure core temperature in bears. the objective of this study was to compare body temperature measured by the handheld digital thermometer (hdt), deep rectally inserted core temperature capsules (ctcs), and gastrically inserted ctcs in anesthetized brown bears (ursus arctos). twenty-two brown bears were immobilized with a combination of zolazepam-tiletamine and xylazine or medetomidine. after immobilization, one ctc ... | 2014 | 25632668 |
| no evidence for the effect of mhc on male mating success in the brown bear. | mate choice is thought to contribute to the maintenance of the spectacularly high polymorphism of the major histocompatibility complex (mhc) genes, along with balancing selection from parasites, but the relative contribution of the former mechanism is debated. here, we investigated the association between male mhc genotype and mating success in the brown bear. we analysed fragments of sequences coding for the peptide-binding region of the highly polymorphic mhc class i and class ii drb genes, wh ... | 2014 | 25470381 |
| [mitochondrial cytochrome b gene variation in brown bear (ursus arctos linnaeus, 1758) from southern part of russian far east]. | the genetic variability of brown bear ursus arctos from the southern part of the russian far east was first ex- amined based on the variations in the mitochondrial dna cytochrome b sequence. the presence of two phylogenetic groups of haplotypes described previously for other parts of the species range was demonstrated. part of the samples belonged to the haplotype group distributed across the whole range, while another part belonged to the rare group previously only reported for japan and alaska ... | 2013 | 25438600 |
| alternative procedures for the cryopreservation of brown bear ejaculates depending on the flexibility of the "in cooling" period (5°c). | the adaptability of cryopreservation protocols for brown bear spermatozoa collected under field conditions and frozen in a nearby laboratory (transported for a few hours) or shipped to a reference laboratory for sex sorting (transported for a few days) was evaluated. forty-nine electroejaculates from 15 mature brown bears were extended to 100×10(6) sperm/ml in a tes-tris-fructose based extender and cryopreserved (-20°c/min to -100°c and stored at -196°c). after thawing, the quality of the semina ... | 2014 | 25315224 |
| salvaging urospermic ejaculates from brown bear (ursus arctos). | the objective of this study was to reverse the osmotic stress of sperm in urine contaminated bear ejaculates that were obtained by electroejaculation using pre-freezing washing or density gradient centrifugation isolation. in experiment 1, ejaculates were divided into six aliquots, five were diluted in each washing extender: 200, 300, 400, 500 and 700 mosm/kg (prepared from a tes-tris-fructose base, adding water or fructose as corresponds), at a 1:2 ratio (raw semen: washing solution, v/v); and ... | 2014 | 25278437 |
| low cardiac output as physiological phenomenon in hibernating, free-ranging scandinavian brown bears (ursus arctos) - an observational study. | despite 5-7 months of physical inactivity during hibernation, brown bears (ursus arctos) are able to cope with physiological conditions that would be detrimental to humans. during hibernation, the tissue metabolic demands fall to 25% of the active state. our objective was to assess cardiac function associated with metabolic depression in the hibernating vs. active states in free-ranging scandinavian brown bears. | 2014 | 25224464 |
| stress and reproductive hormones in grizzly bears reflect nutritional benefits and social consequences of a salmon foraging niche. | physiological indicators of social and nutritional stress can provide insight into the responses of species to changes in food availability. in coastal british columbia, canada, grizzly bears evolved with spawning salmon as an abundant but spatially and temporally constrained food source. recent and dramatic declines in salmon might have negative consequences on bear health and ultimately fitness. to examine broadly the chronic endocrine effects of a salmon niche, we compared cortisol, progester ... | 2013 | 24312230 |
| de novo snp discovery in the scandinavian brown bear (ursus arctos). | information about relatedness between individuals in wild populations is advantageous when studying evolutionary, behavioural and ecological processes. genomic data can be used to determine relatedness between individuals either when no prior knowledge exists or to confirm suspected relatedness. here we present a set of 96 snps suitable for inferring relatedness for brown bears (ursus arctos) within scandinavia. we sequenced reduced representation libraries from nine individuals throughout the g ... | 2013 | 24260529 |
| ancestral polymorphisms and sex-biased migration shaped the demographic history of brown bears and polar bears. | recent studies have reported discordant gene trees in the evolution of brown bears and polar bears. genealogical histories are different among independent nuclear loci and between biparentally inherited autosomal dna (adna) and matrilineal mitochondrial dna (mtdna). based on multi-locus genomic sequences from adna and mtdna, we inferred the population demography of brown and polar bears and found that brown bears have 6 times (adna) or more than 14 times (mtdna) larger population sizes than pola ... | 2013 | 24236053 |
| haematological and biochemical reference intervals for free-ranging brown bears (ursus arctos) in sweden. | establishment of haematological and biochemical reference intervals is important to assess health of animals on individual and population level. reference intervals for 13 haematological and 34 biochemical variables were established based on 88 apparently healthy free-ranging brown bears (39 males and 49 females) in sweden. the animals were chemically immobilised by darting from a helicopter with a combination of medetomidine, tiletamine and zolazepam in april and may 2006-2012 in the county of ... | 2014 | 25139149 |
| grizzly bears exhibit augmented insulin sensitivity while obese prior to a reversible insulin resistance during hibernation. | the confluence of obesity and diabetes as a worldwide epidemic necessitates the discovery of new therapies. success in this endeavor requires translatable preclinical studies, which traditionally employ rodent models. as an alternative approach, we explored hibernation where obesity is a natural adaptation to survive months of fasting. here we report that grizzly bears exhibit seasonal tripartite insulin responsiveness such that obese animals augment insulin sensitivity but only weeks later ente ... | 2014 | 25100064 |
| selenium in brown bears (ursus arctos) from croatia: relation to cadmium and mercury. | muscle (n = 111), liver (n = 111), and kidney cortex (n = 101) samples from brown bears (ursus arctos) were collected in the 2009 and 2010 hunting seasons in croatia and analysed for selenium (se), cadmium (cd), and total mercury (hg). the aim was to assess the levels of these elements according to age, sex, and season of collection, and to investigate possible se/cd and se/hg interactions. median se concentrations were 0.139 μg/g in muscle, 0.409 μg/g in liver and 1.75 μg/g wet mass in kidney c ... | 2014 | 25072771 |
| indigenous knowledge and science unite to reveal spatial and temporal dimensions of distributional shift in wildlife of conservation concern. | range shifts among wildlife can occur rapidly and impose cascading ecological, economic, and cultural consequences. however, occurrence data used to define distributional limits derived from scientific approaches are often outdated for wide ranging and elusive species, especially in remote environments. accordingly, our aim was to amalgamate indigenous and western scientific evidence of grizzly bear (ursus arctos horribilis) records and detail a potential range shift on the central coast of brit ... | 2014 | 25054635 |
| compensatory heterogeneity in spatially explicit capture-recapture data. | spatially explicit capture-recapture methods, used widely to estimate the abundance of large carnivores, allow for movement within home ranges during sampling. probability of detection is a decreasing function of distance from the home range center, with one parameter for magnitude and another for spatial scale. sex-based and other differences in home range size potentially cause heterogeneity in individual detection and bias in estimates of density. the two parameters of detection have hitherto ... | 2014 | 25000765 |
| factors affecting date of implantation, parturition, and den entry estimated from activity and body temperature in free-ranging brown bears. | knowledge of factors influencing the timing of reproduction is important for animal conservation and management. brown bears (ursus arctos) are able to vary the birth date of their cubs in response to their fat stores, but little information is available about the timing of implantation and parturition in free-ranging brown bears. body temperature and activity of pregnant brown bears is higher during the gestation period than during the rest of hibernation and drops at parturition. we compared m ... | 2014 | 24988486 |
| stable isotopes reveal rail-associated behavior in a threatened carnivore. | human-wildlife conflict is a leading cause of adult mortality for large carnivores worldwide. train collision is the primary cause of mortality for threatened grizzly bears (ursus arctos) in banff national park. we investigated the use of stable isotope analysis as a tool for identifying bears that use the railway in banff. rail-associated bears had higher δ(15)n and δ(34)s values than bears sampled away from the rail, but similar δ(13)c values. because elevated δ(15)n values are indicative of h ... | 2014 | 24936982 |
| macronutrient optimization and seasonal diet mixing in a large omnivore, the grizzly bear: a geometric analysis. | nutrient balance is a strong determinant of animal fitness and demography. it is therefore important to understand how the compositions of available foods relate to required balance of nutrients and habitat suitability for animals in the wild. these relationships are, however, complex, particularly for omnivores that often need to compose balanced diets by combining their intake from diverse nutritionally complementary foods. here we apply geometric models to understand how the nutritional compo ... | 2014 | 24841821 |
| a simple and novel method for retrieval of pasteurellaceae from swab samples collected in the field. | traditionally it has been difficult or impossible to collect and preserve bacterial samples of especially fastidious bacteria in mixed primary cultures, unless the samples could be transported to a laboratory within approximately 24 h. therefore, a simple novel method for preserving swab samples until bacterial isolation can be completed in the laboratory was developed and evaluated. pasteurellaceae bacteria were used as a representative for fastidious bacteria. a 7.5% glucose serum medium was u ... | 2013 | 23897719 |
| home range size variation in female arctic grizzly bears relative to reproductive status and resource availability. | the area traversed in pursuit of resources defines the size of an animal's home range. for females, the home range is presumed to be a function of forage availability. however, the presence of offspring may also influence home range size due to reduced mobility, increased nutritional need, and behavioral adaptations of mothers to increase offspring survival. here, we examine the relationship between resource use and variation in home range size for female barren-ground grizzly bears (ursus arcto ... | 2013 | 23844162 |
| papillary cystadenocarcinoma of the mammary gland with metastases to the gastrointestinal tract in a himalayan brown bear (ursus arctos). | a 17-yr-old, multiparous female brown bear (ursus arctos) bred in captivity at the himalayan nature park, kufri, shimla, himachal pradesh, india, died after a short progressive illness of 2 wk duration. clinically, the bear had dyspnea and was pyretic, inappetent, and lethargic. within the right pectoral mammary gland was an 11-cm diameter, round, firm, subcutaneous mass. at postmortem examination, the mammary gland revealed a well-differentiated, multinodular infiltrative mass with multiple non ... | 2013 | 23805565 |
| could brown bears (ursus arctos) have survived in ireland during the last glacial maximum? | brown bears are recorded from ireland during both the late pleistocene and early-mid holocene. although most of the irish landmass was covered by an ice sheet during the last glacial maximum (lgm), irish brown bears are known to have hybridized with polar bears during the late pleistocene, and it is suggested that the irish brown bear population did not become extinct but instead persisted in situ through the lgm in a southwestern ice-free refugium. we use historical population modelling to demo ... | 2013 | 23676655 |
| molecular phylogeography of the brown bear (ursus arctos) in northeastern asia based on analyses of complete mitochondrial dna sequences. | to further elucidate the migration history of the brown bears (ursus arctos) on hokkaido island, japan, we analyzed the complete mitochondrial dna (mtdna) sequences of 35 brown bears from hokkaido, the southern kuril islands (etorofu and kunashiri), sakhalin island, and the eurasian continent (continental russia, bulgaria, and tibet), and those of four polar bears. based on these sequences, we reconstructed the maternal phylogeny of the brown bear and estimated divergence times to investigate th ... | 2013 | 23619144 |
| determinants of lifetime reproduction in female brown bears: early body mass, longevity, and hunting regulations. | in iteroparous mammals, conditions experienced early in life may have long-lasting effects on lifetime reproductive success. human-induced mortality is also an important demographic factor in many populations of large mammals and may influence lifetime reproductive success. here, we explore the effects of early development, population density, and human hunting on survival and lifetime reproductive success in brown bear (ursus arctos) females, using a 25-year database of individually marked bear ... | 2013 | 23600257 |
| size selectivity of predation by brown bears depends on the density of their sockeye salmon prey. | can variation in prey density drive changes in the intensity or direction of selective predation in natural systems? despite ample evidence of density-dependent selection, the influence of prey density on predatory selection patterns has seldom been investigated empirically. we used 20 years of field data on brown bears (ursus arctos) foraging on sockeye salmon (oncorhynchus nerka) in alaska, to test the hypothesis that salmon density affects the strength of size-selective predation. measurement ... | 2013 | 23594549 |
| comment on "nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage". | based on nuclear and mitochondrial dna, hailer et al. (reports, 20 april 2012, p. 344) suggested early divergence of polar bears from a common ancestor with brown bears and subsequent introgression. our population genetic analysis that traces each of the genealogies in the independent nuclear loci does not support the evolutionary model proposed by the authors. | 2013 | 23539580 |
| body temperature during hibernation is highly correlated with a decrease in circulating innate immune cells in the brown bear (ursus arctos): a common feature among hibernators? | hibernation involves periods of severely depressed metabolism (torpor) and decreases in body temperature (tb). small arctic mammals (<5kg), in which tb generally drop drastically, display leukopenia during hibernation. this raised the question of whether the decreased leukocyte counts in mammalian hibernators is due to torpor per se or is secondary to low tb. the present study examined immune cell counts in brown bears (ursus arctos), where torpor is only associated with shallow decreases in tb. ... | 2013 | 23532623 |
| genomic evidence for island population conversion resolves conflicting theories of polar bear evolution. | despite extensive genetic analysis, the evolutionary relationship between polar bears (ursus maritimus) and brown bears (u. arctos) remains unclear. the two most recent comprehensive reports indicate a recent divergence with little subsequent admixture or a much more ancient divergence followed by extensive admixture. at the center of this controversy are the alaskan abc islands brown bears that show evidence of shared ancestry with polar bears. we present an analysis of genome-wide sequence dat ... | 2013 | 23516372 |
| spatial patterns of breeding success of grizzly bears derived from hierarchical multistate models. | conservation programs often manage populations indirectly through the landscapes in which they live. empirically, linking reproductive success with landscape structure and anthropogenic change is a first step in understanding and managing the spatial mechanisms that affect reproduction, but this link is not sufficiently informed by data. hierarchical multistate occupancy models can forge these links by estimating spatial patterns of reproductive success across landscapes. to illustrate, we surve ... | 2014 | 24762089 |
| predator avoidance during reproduction: diel movements by spawning sockeye salmon between stream and lake habitats. | daily movements of mobile organisms between habitats in response to changing trade-offs between predation risk and foraging gains are well established; however, less in known about whether similar tactics are used during reproduction, a time period when many organisms are particularly vulnerable to predators. we investigated the reproductive behaviour of adult sockeye salmon (oncorhynchus nerka) and the activity of their principal predator, brown bears (ursus arctos), on streams in south-western ... | 2014 | 24702169 |
| tolerance of brown bear spermatozoa to conditions of pre-freezing cooling rate and equilibration time. | specific protocols for the cryopreservation of endangered cantabrian brown bear spermatozoa are critical to create a genetic resource bank. the aim of this study was to assess the effect of cooling rates and equilibration time before freezing on post-thawed brown bear spermatozoa quality. electroejaculates from 11 mature bears were extended to 100 × 10(6) spermatozoa/ml in a tes-tris-fructose-based extender, cryopreserved following performance of the respective cooling/equilibration protocol eac ... | 2014 | 24629590 |
| pitfalls in comparing modern hair and fossil bone collagen c and n isotopic data to reconstruct ancient diets: a case study with cave bears (ursus spelaeus). | stable isotope analyses provide one of the few means to evaluate diet of extinct taxa. however, interpreting isotope data from bone collagen of extinct animals based on isotopic patterns in different tissues of modern animal proxies is precarious. for example, three corrections are needed before making comparisons of recent hair and ancient bone collagen: calibration of carbon-13 variations in atmospheric co2, different isotopic discrimination between diet-hair keratin and diet-bone collagen, an ... | 2014 | 24588112 |
| admixture and gene flow from russia in the recovering northern european brown bear (ursus arctos). | large carnivores were persecuted to near extinction during the last centuries, but have now recovered in some countries. it has been proposed earlier that the recovery of the northern european brown bear is supported by migration from russia. we tested this hypothesis by obtaining for the first time continuous sampling of the whole finnish bear population, which is located centrally between the russian and scandinavian bear populations. the finnish population is assumed to experience high gene f ... | 2014 | 24839968 |
| linking genotype, ecotype, and phenotype in an intensively managed large carnivore. | numerous factors influence fitness of free-ranging animals, yet often these are uncharacterized. we integrated gps habitat use data and genetic profiling to determine their influence on fitness proxies (mass, length, and body condition) in a threatened population of grizzly bears (ursus arctos) in alberta, canada. we detected distinct genetic and habitat use (ecotype) clusters, with individual cluster assignments, or genotype/ecotype, being correlated (pearson r = 0.34, p < 0.01). related indivi ... | 2014 | 24567749 |
| decrease in the red cell cofactor 2,3-diphosphoglycerate increases hemoglobin oxygen affinity in the hibernating brown bear ursus arctos. | during winter hibernation, brown bears (ursus arctos) reduce basal o(2) consumption rate to ∼25% compared with the active state, while body temperature decreases moderately (to ∼30°c), suggesting a temperature-independent component in their metabolic depression. to establish whether changes in o(2) consumption during hibernation correlate with changes in blood o(2) affinity, we took blood samples from the same six individuals of hibernating and nonhibernating free-ranging brown bears during wint ... | 2013 | 23174858 |
| genetic relationships of extant brown bears (ursus arctos) and polar bears (ursus maritimus). | polar bears (ursus maritimus) and brown bears (ursus arctos) are closely related species for which extensive mitochondrial and nuclear phylogenetic comparisons have been made. we used previously published genotype data for 8 microsatellite dna loci from 930 brown bears in 19 populations and 473 polar bears in 16 populations to compare the population genetic relationships of extant populations of the species. genetic distances (nei standard distance = 1.157), the proportion of private alleles (52 ... | 2012 | 23125409 |
| bears are simply voles writ large: social structure determines the mechanisms of intrinsic population regulation in mammals. | the literature reveals opposing views regarding the importance of intrinsic population regulation in mammals. different models have been proposed; adding importance to contrasting life histories, body sizes and social interactions. here we evaluate current theory based on results from two scandinavian projects studying two ecologically different mammal species with contrasting body sizes and life history traits: the root vole microtus oeconomus and the brown bear ursus arctos. we emphasize four ... | 2014 | 24481982 |
| the effects of automated scatter feeders on captive grizzly bear activity budgets. | although captive bears are popular zoo attractions, they are known to exhibit high levels of repetitive behaviors (rbs). these behaviors have also made them particularly popular subjects for welfare research. to date, most research on ursid welfare has focused on various feeding methods that seek to increase time spent searching for, extracting, or consuming food. prior research indicates an average of a 50% reduction in rbs when attempts are successful and, roughly, a 50% success rate across st ... | 2014 | 24467390 |
| sampling designs matching species biology produce accurate and affordable abundance indices. | wildlife biologists often use grid-based designs to sample animals and generate abundance estimates. although sampling in grids is theoretically sound, in application, the method can be logistically difficult and expensive when sampling elusive species inhabiting extensive areas. these factors make it challenging to sample animals and meet the statistical assumption of all individuals having an equal probability of capture. violating this assumption biases results. does an alternative exist? per ... | 2013 | 24392290 |
| spatial analysis of factors influencing long-term stress in the grizzly bear (ursus arctos) population of alberta, canada. | non-invasive measures for assessing long-term stress in free ranging mammals are an increasingly important approach for understanding physiological responses to landscape conditions. using a spatially and temporally expansive dataset of hair cortisol concentrations (hcc) generated from a threatened grizzly bear (ursus arctos) population in alberta, canada, we quantified how variables representing habitat conditions and anthropogenic disturbance impact long-term stress in grizzly bears. we charac ... | 2013 | 24386273 |
| environmental factors and habitat use influence body condition of individuals in a species at risk, the grizzly bear. | metrics used to quantify the condition or physiological states of individuals provide proactive mechanisms for understanding population dynamics in the context of environmental factors. our study examined how anthropogenic disturbance, habitat characteristics and hair cortisol concentrations interpreted as a sex-specific indicator of potential habitat net-energy demand affect the body condition of grizzly bears (n = 163) in a threatened population in alberta, canada. we quantified environmental ... | 2014 | 27293664 |
| quantifying long-term stress in brown bears with the hair cortisol concentration: a biomarker that may be confounded by rapid changes in response to capture and handling. | the measurement of cortisol in hair is becoming important in studying the role of stress in the life history, health and ecology of wild mammals. the hair cortisol concentration (hcc) is generally believed to be a reliable indicator of long-term stress that can reflect frequent or prolonged activation of the hypothalamic-pituitary-adrenal axis over weeks to months through passive diffusion from the blood supply to the follicular cells that produce the hair. diffusion of cortisol from tissues sur ... | 2014 | 27293647 |
| stress and reproductive hormones reflect inter-specific social and nutritional conditions mediated by resource availability in a bear-salmon system. | food availability can influence the nutritional and social dynamics within and among species. our investigation focused on grizzly and black bears in coastal british columbia, canada, where recent and dramatic declines in their primary prey (salmon) raise concerns about potentially negative effects on bear physiology. we examined how salmon availability relates to stress and reproductive hormones in coastal grizzly (n = 69) and black bears (n = 68) using cortisol and testosterone. in hair sample ... | 2014 | 27293631 |
| [new data on the phylogeography and genetic diversity of the brown bear ursus arctos linnaeus, 1758 of northeastern eurasia (mtdna control region polymorphism analysis)]. | an analysis of polymorphism of the fragment of the control region of mitochondrial dna of 53 tissue samples of the brown bear ursus arctos from several regions of the eastern part of russia was carried out. it was found that most of the described haplotypes belong to cluster 3a, the most common in eurasia, and do not form regionally specific haplogroups. however, among the bears from western and eastern siberia, as well as the island of kunashir, three haplotypes were identified, which are close ... | 2016 | 25735154 |
| predicting grizzly bear density in western north america. | conservation of grizzly bears (ursus arctos) is often controversial and the disagreement often is focused on the estimates of density used to calculate allowable kill. many recent estimates of grizzly bear density are now available but field-based estimates will never be available for more than a small portion of hunted populations. current methods of predicting density in areas of management interest are subjective and untested. objective methods have been proposed, but these statistical models ... | 2013 | 24367552 |
| perception of human-derived risk influences choice at top of the food chain. | on human-used landscapes, animal behavior is a trade-off between maximizing fitness and minimizing human-derived risk. understanding risk perception in wildlife can allow mitigation of anthropogenic risk, with benefits to long-term animal fitness. areas where animals choose to rest should minimize risk from predators, which for large carnivores typically equate to humans. we hypothesize that high human activity leads to selection for habitat security, whereas low activity enables trading securit ... | 2013 | 24367549 |
| confronting uncertainty in wildlife management: performance of grizzly bear management. | scientific management of wildlife requires confronting the complexities of natural and social systems. uncertainty poses a central problem. whereas the importance of considering uncertainty has been widely discussed, studies of the effects of unaddressed uncertainty on real management systems have been rare. we examined the effects of outcome uncertainty and components of biological uncertainty on hunt management performance, illustrated with grizzly bears (ursus arctos horribilis) in british co ... | 2013 | 24223134 |
| immobilization of grizzly bears (ursus arctos) with dexmedetomidine, tiletamine, and zolazepam. | safe and effective immobilization of grizzly bears (ursus arctos) is essential for research and management. fast induction of anesthesia, maintenance of healthy vital rates, and predictable recoveries are priorities. from september 2010 to may 2012, we investigated these attributes in captive and wild grizzly bears anesthetized with a combination of a reversible α2 agonist (dexmedetomidine [dexm], the dextrorotatory enantiomer of medetomidine) and a nonreversible n-methyl-d-aspartate (nmda) agon ... | 2014 | 24171564 |
| brown bear sperm double freezing: effect of elapsed time and use of puresperm(®) gradient between freeze-thaw cycles. | the use of sexed spermatozoa has great potential to captive population management in endangered wildlife. the problem is that the sex-sorting facility is a long distance from the semen collection place and to overcome this difficulty two freeze-thaw cycles may be necessary. in this study, effects of refreezing on brown bear electroejaculated spermatozoa were analyzed. we carried out two experiments: (1) to assess the effects of the two freezing-thawing cycles on sperm quality and to analyze thre ... | 2013 | 24135084 |
| nuclear genomic sequences reveal that polar bears are an old and distinct bear lineage. | recent studies have shown that the polar bear matriline (mitochondrial dna) evolved from a brown bear lineage since the late pleistocene, potentially indicating rapid speciation and adaption to arctic conditions. here, we present a high-resolution data set from multiple independent loci across the nuclear genomes of a broad sample of polar, brown, and black bears. bayesian coalescent analyses place polar bears outside the brown bear clade and date the divergence much earlier, in the middle pleis ... | 2012 | 22517859 |
| how much lox is a grizzly bear worth? | using grizzly bears as surrogates for "salmon ecosystem" function, the authors develop a generalizable ecosystem-based management framework that enables decision makers to quantify ecosystem-harvest tradeoffs between wild and human recipients of natural resources like fish. | 2012 | 22505846 |
| a forensic dna profiling system for northern european brown bears (ursus arctos). | a set of 13 dinucleotide str loci (g1a, g10b, g1d, g10l, mu05, mu09, mu10, mu15, mu23, mu26, mu50, mu51, mu59) were selected as candidate markers for a dna forensic profiling system for northern european brown bear (ursus arctos). we present results from validation of the markers with respect to their sensitivity, species specificity and performance (precision, heterozygote balance and stutter ratios). all strs were amplified with 0.6ng template input, and there were no false bear genotypes in t ... | 2012 | 22483764 |
| dna metabarcoding multiplexing and validation of data accuracy for diet assessment: application to omnivorous diet. | ecological understanding of the role of consumer-resource interactions in natural food webs is limited by the difficulty of accurately and efficiently determining the complex variety of food types animals have eaten in the field. we developed a method based on dna metabarcoding multiplexing and next-generation sequencing to uncover different taxonomic groups of organisms from complex diet samples. we validated this approach on 91 faeces of a large omnivorous mammal, the brown bear, using dna met ... | 2014 | 24128180 |
| infanticide as a male reproductive strategy has a nutritive risk effect in brown bears. | behavioural strategies to reduce predation risk can incur costs, which are often referred to as risk effects. a common strategy to avoid predation is spatio-temporal avoidance of predators, in which prey typically trade optimal resources for safety. analogous with predator-prey theory, risk effects should also arise in species with sexually selected infanticide (ssi), in which females with dependent offspring avoid infanticidal males. ssi can be common in brown bear (ursus arctos) populations an ... | 2013 | 24088563 |
| validation of a novel cognitive bias task based on difference in quantity of reinforcement for assessing environmental enrichment. | cognitive bias tasks purport to assess affective states via responses to ambiguous stimuli. we hypothesized that a novel cognitive bias task based on positive reinforcement using quantity differences would detect changes in affect in captive grizzly bears (ursus arctos horribilis). we trained bears (n = 8) to respond differently (nose or paw touch) to two stimuli (light or dark gray cue cards), with responses counterbalanced across bears. the two cues signaled a small or large food reward, respe ... | 2014 | 24045850 |
| male reproductive strategy explains spatiotemporal segregation in brown bears. | spatiotemporal segregation is often explained by the risk for offspring predation or by differences in physiology, predation risk vulnerability or competitive abilities related to size dimorphism. most large carnivores are size dimorphic and offspring predation is often intraspecific and related to nonparental infanticide (npi). npi can be a foraging strategy, a strategy to reduce competition, or a male reproductive strategy. spatiotemporal segregation is widespread among large carnivores, but i ... | 2013 | 23461483 |
| plant consumption by grizzly bears reduces biomagnification of salmon-derived polychlorinated biphenyls, polybrominated diphenyl ethers, and organochlorine pesticides. | the present study characterizes the uptake and loss of persistent organic pollutants (pops) in grizzly bears (ursus arctos horribilis) by sampling and analyzing their terrestrial and marine foods and fecal material from a remote coastal watershed in british columbia, canada. the authors estimate that grizzly bears consume 341 to 1,120 µg of polychlorinated biphenyls (pcbs) and 3.9 to 33 µg of polybrominated diphenyl ethers daily in the fall when they have access to an abundant supply of returnin ... | 2013 | 23401324 |
| physiologic evaluation of capture and anesthesia with medetomidine-zolazepam-tiletamine in brown bears (ursus arctos). | physiologic variables during anesthesia with medetomidine-zolazepam-tiletamine were evaluated in 52 free-ranging brown bears (ursus arctos) darted from a helicopter and in six captive brown bears darted at a zoo. during anesthesia, rectal temperature, respiratory rate, heart rate, and pulse oximetry derived hemoglobin oxygen saturation were recorded. arterial blood samples were collected and immediately analyzed for evaluation of pulmonary gas exchange, acid-base status, and selected hematologic ... | 2011 | 22946363 |
| complete mitochondrial genome of a pleistocene jawbone unveils the origin of polar bear. | the polar bear has become the flagship species in the climate-change discussion. however, little is known about how past climate impacted its evolution and persistence, given an extremely poor fossil record. although it is undisputed from analyses of mitochondrial (mt) dna that polar bears constitute a lineage within the genetic diversity of brown bears, timing estimates of their divergence have differed considerably. using next-generation sequencing technology, we have generated a complete, hig ... | 2010 | 20194737 |
| does learning or instinct shape habitat selection? | habitat selection is an important behavioural process widely studied for its population-level effects. models of habitat selection are, however, often fit without a mechanistic consideration. here, we investigated whether patterns in habitat selection result from instinct or learning for a population of grizzly bears (ursus arctos) in alberta, canada. we found that habitat selection and relatedness were positively correlated in female bears during the fall season, with a trend in the spring, but ... | 2013 | 23341983 |
| the antioxidant effects of soybean lecithin- or low-density lipoprotein-based extenders for the cryopreservation of brown-bear (ursus arctos) spermatozoa. | egg yolk low-density lipoproteins (ldl) and soybean lecithin were evaluated as replacements for egg yolk in extenders used for the cryopreservation of brown-bear spermatozoa. the motility, viability and acrosomal status of post-thawed spermatozoa were analysed, and an egg-yolk extender was used as a control. the total antioxidant capacity of these extenders was tested. soybean lecithin showed an effect that was dependent on the soybean concentration (2%, 3.5% and 5%) and source (type a: 24% l-α- ... | 2013 | 23312130 |
| bear maulings treated in calgary, alberta: their management and sequelae. | between 1994 and 2005, seven patients underwent surgery at the foothills medical centre, calgary, alberta, for injuries sustained in bear maulings. the purpose of the present study was to document these cases and add to the literature on the management and the potential complications of bear attacks. | 2006 | 19554108 |
| grizzly bears, salmon, and contaminant transport. | | 2005 | 16201606 |
| balancing precision and risk: should multiple detection methods be analyzed separately in n-mixture models? | using multiple detection methods can increase the number, kind, and distribution of individuals sampled, which may increase accuracy and precision and reduce cost of population abundance estimates. however, when variables influencing abundance are of interest, if individuals detected via different methods are influenced by the landscape differently, separate analysis of multiple detection methods may be more appropriate. we evaluated the effects of combining two detection methods on the identifi ... | 2012 | 23251342 |
| the addition of heat shock protein hspa8 to cryoprotective media improves the survival of brown bear (ursus arctos) spermatozoa during chilling and after cryopreservation. | the cantabrian brown bear survives as a small remnant population in northern spain and semen cryopreservation for future artificial insemination is one of the measures being implemented for conservation of this species. as part of this program we investigated the value of adding heat shock protein a8 (hspa8) to media (n-[tris(hydroxymethyl)methyl]-2-aminoethanesulfonic acid-tris-fructose with 20% egg yolk) used for chilling and cryopreserving the spermatozoa. semen samples from eight brown bears ... | 2013 | 23237481 |
| administration of antiprogestin j956 for contraception in bears: a pharmacological study. | effective and reversible control of reproduction in bears is highly desirable for conservation and management programs in zoos to establish genetically variable ex-situ populations of bears within the constraints of limited space in captivity. the reproductive physiology of bears is characterized by two main traits--seasonality and delayed implantation, which is progesterone dependent. this offers the opportunity to interrupt early pregnancy by short-term administration of antiprogestins. the ai ... | 2001 | 11572441 |
| the percentage of spermatozoa lost during the centrifugation of brown bear (ursus arctos) ejaculates is associated with some spermatozoa quality and seminal plasma characteristics. | cryopreservation of brown bear (ursus arctos) semen requires centrifugation to increase concentration and/or remove urine contamination. however, a percentage of the spermatozoa are lost in the process. this percentage varies considerably between males and ejaculates, and we have studied the effect of sperm quality and seminal plasma characteristics on the spermatozoa recovery rate after centrifugation. one hundred and thirty one sperm samples obtained from fifteen brown bear males by electroeja ... | 2012 | 23084761 |
| spinal cord compression in two related ursus arctos horribilis. | two 15-yr-old grizzly bear littermates were evaluated within 9 mo of each other with the symptom of acute onset of progressive paraparesis and proprioceptive ataxia. the most significant clinical examination finding was pelvic limb paresis in both bears. magnetic resonance examinations of both bears showed cranial thoracic spinal cord compression. the first bear had left-sided extradural, dorsolateral spinal cord compression at t3-t4. vertebral canal stenosis was also observed at t2-t3. images o ... | 2012 | 23082524 |
| reciprocal modulation of internal and external factors determines individual movements. | movement is fundamental to individual and population dynamics, as it allows individuals to meet their basic requirements. although movement patterns reflect interactions between internal and external factors, only few studies have examined the effects of these factors on movement simultaneously, and they generally focused on particular biological contexts (e.g. dispersal, foraging). however, the relative importance of these factors in driving individual routine movements might reflect a species' ... | 2013 | 23039315 |
| temporal organization of activity in the brown bear (ursus arctos): roles of circadian rhythms, light, and food entrainment. | seasonal cycles of reproduction, migration, and hibernation are often synchronized to changes in daylength (photoperiod). ecological and evolutionary pressures have resulted in physiological specializations enabling animals to occupy a particular temporal niche within the diel cycle leading to characteristic activity patterns. in this study, we characterized the annual locomotor activity of captive brown bears (ursus arctos). locomotor activity was observed in 18 bears of varying ages and sexes ... | 2012 | 22972838 |
| gene flow between insular, coastal and interior populations of brown bears in alaska. | the brown bears of coastal alaska have been recently regarded as comprising from one to three distinct genetic groups. we sampled brown bears from each of the regions for which hypotheses of genetic uniqueness have been made, including the bears of the kodiak archipelago and the bears of admiralty, baranof and chichagof (abc) islands in southeast alaska. these samples were analysed with a suite of nuclear microsatellite markers. the 'big brown bears' of coastal alaska were found to be part of th ... | 1998 | 9787441 |
| an empirical evaluation of genetic distance statistics using microsatellite data from bear (ursidae) populations. | a large microsatellite data set from three species of bear (ursidae) was used to empirically test the performance of six genetic distance measures in resolving relationships at a variety of scales ranging from adjacent areas in a continuous distribution to species that diverged several million years ago. at the finest scale, while some distance measures performed extremely well, statistics developed specifically to accommodate the mutational processes of microsatellites performed relatively poor ... | 1997 | 9409849 |
| seasonal variations of blood haptoglobin level of brown bears in japan. | haptoglobin (hp), a hemoglobin-binding protein, is known as an acute phase protein increasing in blood during inflammation in most mammals. on the basis of our previous studies on purification and characterization of bear hp (comp. biochem. physiol. 110b, 785-789, 1995), in this study, we developed an immunoassay method to measure serum hp level in bear, and measured the concentration of hp in blood samples collected from 84 reared and 25 wild brown bears in hokkaido, japan. the mean serum hp co ... | 1996 | 8759283 |
| using a reference population yardstick to calibrate and compare genetic diversity reported in different studies: an example from the brown bear. | in species with large geographic ranges, genetic diversity of different populations may be well studied, but differences in loci and sample sizes can make the results of different studies difficult to compare. yet, such comparisons are important for assessing the status of populations of conservation concern. we propose a simple approach of using a single well-studied reference population as a 'yardstick' to calibrate results of different studies to the same scale, enabling comparisons. we use a ... | 2012 | 22850697 |
| climate and reproduction of grizzly bears in yellowstone national park. | | 1978 | 567281 |
| [conditioned reflexes in brown bears to relative and absolute values of cues]. | | 1971 | 5563664 |
| [amino oxidases in the blood serum and in some tissues of brown bears and snakes]. | | 2013 | 14120394 |
| grizzly bears: skulls wanted. | | 1914 | 17781833 |
| capture, anesthesia, and disturbance of free-ranging brown bears (ursus arctos) during hibernation. | we conducted thirteen immobilizations of previously collared hibernating two- to four-year-old brown bears (ursus arctos) weighing 21-66 kg in central sweden in winter 2010 and 2011 for comparative physiology research. here we report, for the first time, an effective protocol for the capture and anesthesia of free-ranging brown bears during hibernation and an assessment of the disturbance the captures caused. bears were darted in anthill, soil, or uprooted tree dens on eleven occasions, but two ... | 2012 | 22815757 |