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Interactions among recreational users and grizzly bears (Ursus arctos) are a continuous challenge for bear managers. Yellowstone National Park, Wyoming, USA uses a system of designated backcountry campsites to manage overnight use and provides bear-resistant food-storage devices for recreational users. Few studies have evaluated how this type of management and recreation influences grizzly bear behavior. We used global positioning system (GPS) data for humans and bears to determine how overnight use influenced grizzly bear movement behavior. We determined times of day campsites were occupied and contrasted grizzly bear locations to random locations near occupied campsites. We conducted a similar analysis ignoring campsite occupancy to assess the utility of including a temporal variable. Grizzly bears were 0.35 times as likely as random locations to be ≤200 m from occupied campsites (95% CI = 0.19–0.62, P ≤ 0.001). Conversely, when human occupancy was ignored, bears were 2.11 times more likely than random locations to be ≤200 m from campsites (95% CI = 1.85–2.41, P ≤ 0.001). We conclude that overnight backcountry camping can displace grizzly bears within 200 m of campgrounds. To avoid confounding results, we suggest considering use of a temporal variable in studies of human–bear interactions.
Supplemental feeding is often believed to be a successful tool for reducing human–bear (Ursus arctos) conflicts, especially in Europe. However, effectiveness of this measure is poorly understood and there is growing concern for potential negative side-effects. This is particularly true for supplemental feeding using livestock carrion. Carrion feeding is considered especially effective in reducing livestock depredations by diverting bears from pastures and meeting their protein needs. In Slovenia, year-round supplementary feeding of bears with livestock carrion and corn was intensive and in some areas practiced for over 100 years. However, in 2004 the use of livestock carrion was banned in accordance with European Union regulations. This provided an opportunity to study the effects of carrion feeding on livestock depredations by bears. We used sheep as they represented 97% of all depredation events by brown bears in Slovenia. We analyzed whether bears selectively used carrion feeding stations over corn feeding stations (i.e., indicating that carrion might be more effective in diverting bears from sheep pastures) during 1994–2011, and compared the annual frequency and seasonal distribution of sheep depredations 5 years before and after the ban on livestock carrion feeding during 1999–2009. We found no support that bears selected carrion feeding sites over feeding sites with corn. When controlled for changes in bear and sheep numbers, there was no indication that the ban on carrion feeding increased sheep depredations. Moreover, complementary data indicated that natural protein sources were considerably more important than livestock carrion and that use of carrion peaked in spring, when sheep are rarely outdoors and thus unavailable for depredation. Because of the observed lack of effectiveness, high costs, and potential negative side-effects, we discourage supplemental feeding with livestock carrion to reduce livestock depredations.
Wildlife management personnel often transport human food-conditioned (FC) bears (Ursidae) from developed areas (areas with high human-use) to undeveloped areas to reduce the number of bear incidents and property damage in developed areas. Our goal was to determine if American black bears (Ursus americanus) return to developed areas after being transported to undeveloped areas in Yosemite National Park. Using capture records (1992–2011) for 29 bears transported in 2006–08, we determined if FC (n = 20) and not human food-conditioned (NFC; n = 9) bears were equally likely to return to developed areas following transport. We also reported the fate of these transported bears through 2011. We found that FC bears were more likely to return to developed areas than NFC bears. Of the 16 returning bears, 15 were FC (9 juveniles, 6 adults) and one was NFC. The other 8 NFC bears were never reported as entering developed areas, and no NFC bears were reported as killed. By 2011, 65% of FC bears (13 of 20) were euthanized by wildlife management personnel (n = 10) or harvested near developed areas (n = 3). We recommend that Yosemite National Park discontinue the transport of FC bears and consider removing problem bears from the population.
Species distribution models are used in ecology and conservation biology to draw inferences about the drivers of species' ranges. However, poor conceptual background, environmental variable selection, and algorithm selection can contribute to misleading model predictions. We assessed the effects of environment variable selection and compared statistical performance and output maps of correlative resource- and biotope-based models for estimating the habitat and potential distribution of the Andean bear (Tremarctos ornatus) in Bolivia's Tropical Andes. The resource-based approach estimated bear habitat using 7 resources associated with 3 ecological functions: feeding, shelter, and access to water. In contrast, the biotope model described the habitat by applying 11 environmental predictors related to topography, vegetation, and human activities. Both models performed equally well overall and better than random, with shelter as the most influential variable for the resource model and Yunga forest for the biotope model. However, discrepancies in the extent and arrangement of predicted bear distribution between models differed and emphasized the effect of variable selection, which could influence the delineation of conservation areas for this species. We suggest using a resource-based approach when modelling species distribution because of the more direct relationship to the species investigated and greater ease of interpreting results.
Quantitative documentation of bear (Ursidae) mating behavior is sparse and incomplete. Understanding subtleties of mating behavior and how it differs between successful and unsuccessful mate pairings is a crucial first step to permit empirical testing of sexual selection hypotheses and to inform captive breeding efforts. Because bears possess extremely sensitive olfactory systems and are well known for marking behaviors, it is probable that they are able to sense reproductive status of conspecifics using chemosensory cues. However, very little is currently known of these phenomena in most bear species, including American black bears (Ursus americanus). Our study documents the entire consummatory phase of mating behavior and provides behavioral evidence of chemosensory communication of estrus status in American black bears. Using quantitative ethological methods, we discovered that successful mounts (with ejaculation) averaged 29-fold longer duration than unsuccessful mounts, with no overlap. Males were selective as to which specific estrus (of polyestrous females) and what day within a peak estrus they successfully mounted, and most investigated the females' anogenital region before mounting. Also, females housed together had synchronized estruses. We suggest it is feasible to estimate whether the mating activity of free-ranging bears is successful using only partial observation of the event (first 20 min). Moreover, our study supports the conclusion that chemosensory communication is used by black bears to identify conspecific estrus status. These data advance our basic understanding of bear mating behavior, are applicable to bear wildlife management and conservation efforts, and lay the foundation for further study of the ecology and evolution of sexual selection in bears.
Remains of bowhead whales (Balaena mysticetus) harvested by Iñupiat whalers are deposited in bone piles along the coast of Alaska and have become persistent and reliable food sources for polar bears (Ursus maritimus). The importance of bone piles to individuals and the population, the patterns of use, and the number, sex, and age of bears using these resources are poorly understood. We implemented barbed-wire hair snaring to obtain genetic identities from bears using the Point Barrow bone pile in winter 2010–11. Eighty-three percent of genotyped samples produced individual and sex identification. We identified 97 bears from 200 samples. Using genetic mark–recapture techniques, we estimated that 228 bears used the bone pile during November to February, which would represent approximately 15% of the Southern Beaufort Sea polar bear subpopulation, if all bears were from this subpopulation. We found that polar bears of all age and sex classes simultaneously used the bone pile. More males than females used the bone pile, and males predominated in February, likely because 1/3 of adult females would be denning during this period. On average, bears spent 10 days at the bone pile (median = 5 days); the probability that an individual bear remained at the bone pile from week to week was 63% for females and 45% for males. Most bears in the sample were detected visiting the bone pile once or twice. We found some evidence of matrilineal fidelity to the bone pile, but the group of animals visiting the bone pile did not differ genetically from the Southern Beaufort Sea subpopulation, nor did patterns of relatedness. We demonstrate that bowhead whale bone piles may be an influential food subsidy for polar bears in the Barrow region in autumn and winter for all sex and age classes.
The sloth bear (Melursus ursinus) is a threatened species endemic to the Indian subcontinent. To date, no reliable method has been developed for identifying individuals or monitoring their populations. Here we describe a non-invasive genetic monitoring technique for individual identification of sloth bears. After testing 18 microsatellites developed for other carnivore species, including ursids, we optimized a panel of 7 highly polymorphic microsatellite loci that yielded a cumulative Probability of Identity between siblings value of 2.15E-03. We used this panel to identify 55 individual sloth bears from 190 fecal and 4 hair samples collected in tiger reserves in central India. This panel can be used for population genetic studies and population monitoring of sloth bears.
GPS collars have greatly increased the number of locations obtained for individual animals during telemetry studies, but missed location attempts (missed fixes) may create bias in habitat analyses unless appropriately modeled. We placed GPS collars on captive grizzly bears (Ursus arctos) and observed their behavior while the collars attempted to obtain locations. Bear behavior influenced indices of GPS signal attenuation, the angle of the GPS antenna to the horizon, and collar height above the ground, but because bears sometimes rotate their collars, antenna angle varied within a behavior, particularly when collars fit snugly. We used a model selection approach to evaluate the influence of the angle of the GPS antenna to the horizon, collar height above the ground, and bear behavior on fix success. The model with both antenna angle and collar height was most parsimonious. We recommend fitting GPS collars such that the GPS antenna is opposite the battery pack (i.e., oriented up) for greatest fix success. Because collars sometimes rotate, sensors recording the antenna's angle to the horizon and bear height would help researchers model missed fixes related to signal attenuation caused by behavior. Although captive bear behavior may differ from wild bears, we provide a first look at the relative influences of antenna angle, antenna height, and bear behavior. When antenna angle and height information is not available, using activity sensors and bear movement rates to identify resting behavior should be considered to reduce bias in habitat analyses of GPS collar data.