We present a new paradigm for understanding habituation and the role it plays in brown bear (Ursus arctos) populations and interactions with humans in Alaska. We assert that 3 forms of habituation occur in Alaska: bear-to-bear, bear-to-human, and human-to-bear. We present data that supports our theory that bear density is an important factor influencing a bear's overt reaction distance (ORD); that as bear density increases, overt reaction distance decreases, as does the likelihood of bear–human interactions. We maintain that the effects of bear-to-bear habituation are largely responsible for not only shaping bear aggregations but also for creating the relatively safe environment for bear viewing experienced at areas where there are high densities of brown bears. By promoting a better understanding of the forces that shape bear social interactions within populations and with humans that mingle with them, we can better manage human activities and minimize bear–human conflict.

We assess the potential for American black bears (Ursus americanus) to limit the growth of colonizing or severely reduced grizzly bear (Ursus arctos) populations. Managers are faced with the challenge of increasing the size of small (N < 75) grizzly bear populations in the North Cascade, Selkirk, Cabinet–Yaak, and Bitterroot recovery areas of the USA and Canada. These populations are mainly limited by human-caused mortality. However, other factors such as competition from black bears could impose additional constraints. Brown and grizzly bears and American black bears evolved separately until about 13,000 years ago and, as a probable consequence, they can have substantial diet overlap. Where meat and roots are available, grizzly bears consume more of these foods than do black bears. Where fleshy fruits and succulent forbs are the primary high quality bear foods, as in the North Cascade, Selkirk, and Cabinet–Yaak ecosystems, dietary overlap between grizzly and black bears can be almost complete. Largely because they are smaller, black bears can exist at roughly 10 times the density of grizzly bears, use ranges that are, on average, four-fifths smaller, and are more efficient than grizzly bears at using low densities of small berries. We postulate that the primary impact of black bears on grizzly bears is through reduced reproduction and recruitment caused by exploitation competition, despite the documented ability of most grizzly bears to dominate most black bears during physical confrontations. Such an effect would be greatest in areas where both species rely on berries and forbs, where grizzly bear populations have been extirpated, substantially reduced, or are absent but within dispersal distance, and where black bear populations are comparatively robust. On this basis we postulate that exploitation competition by resident black bears, together with mortality caused by Native Americans, slowed or even curbed the invasion of grizzly bears east across North America during the late Pleistocene and early Holocene. We also postulate that grizzly bears are absent on some coastal islands within dispersal distance of robust grizzly bear populations because of competitive exclusion by black bears.

 We used Doncaster's test to differentiate home range overlap in range use from mutual attraction in grizzly bears (Ursus arctos) based on global positioning system (GPS) telemetry data. From a sample of 61 collared bears, 404 pairs of GPS locations placed 2 or more bears ≤500 m from each other at about the same time (within 3 hr). From these 404 pairs, 68 were significantly positive associations (mutual attraction) in which 65% were male–female (MF) and 35% were the same sex. Most MF associations involved adults. Male and female bears had associations with 1.8 and 1.2 partners/year, respectively. Associations between males occurred twice as often in the pre-berry season than in the berry season, whereas female–female (FF) associations occurred more frequently in the berry season. The length of same-sex associations was significantly shorter than MF associations. Fifty-one percent of MF pairs associated more than once within a single year. For MF associations, the mean distance between individuals was 152 m. Our findings suggest that grizzly bears can spend a considerable amount of time interacting with conspecifics and that behavioral interactions between grizzly bears are more complicated than we understand. Human activity that affects grizzly bear associations could disrupt social behavior and ultimately reproduction.

Pondweeds (Potamogeton spp.) are common foods of waterfowl throughout the Northern Hemisphere. However, consumption of pondweeds by bears has been noted only once, in Russia. We documented consumption of pondweed rhizomes by grizzly bears (Ursus arctos) in the Yellowstone region, 1977–96, during investigations of telemetry locations obtained from 175 radiomarked bears. We documented pondweed excavations at 25 sites and detected pondweed rhizomes in 18 feces. We observed grizzly bears excavating and consuming pondweed on 2 occasions. All excavations occurred in wetlands that were inundated during and after snowmelt, but dry by late August or early September of most years. These wetlands were typified by the presence of inflated sedge (Carex vesicaria) and occurred almost exclusively on plateaus of Pliocene–Pleistocene detrital sediments or volcanic rhyolite flows. Bears excavated wetlands with pondweeds when they were free of standing water, most commonly during October and occasionally during spring prior to the onset of terminal snowmelt. Most excavations were about 4.5 cm deep, 40 cubic decimeter (dm³) in total volume, and targeted the thickened pondweed rhizomes. Starch content of rhizomes collected near grizzly bear excavations averaged 28% (12% SD; n = 6). These results add to the documented diversity of grizzly bear food habits and, because pondweed is distributed circumboreally, also raise the possibility that consumption of pondweed by grizzly bears has been overlooked in other regions.

The Parsnip River area in British Columbia (BC), Canada, provides important habitat for grizzly bears (Ursus arctos). This area contains 2 adjacent topographic regions: (1) a relatively pristine portion of the Hart Ranges of the Canadian Rocky Mountains, and (2) a plateau on which timber harvests have occurred. Increasing human modification of both landscapes may affect the quality of grizzly bear habitat. Therefore, we examined denning behavior and den-site selection of grizzly bears in this area based on data from 61 grizzly bears radiocollared between 1997 and 2002 (34 plateau, 27 mountain bears). Adult females residing in the mountainous landscape arrived earlier to their denning areas (14 Oct versus 26 Oct), entered dens earlier (23 Oct versus 9 Nov), and emerged later (11 May versus 24 Apr) than plateau females, spending on average 36 days longer in their dens (200 days versus 164 days). Dens used in consecutive years by mountain females tended to be closer to one another (x̄ = 2.4 km) than those of plateau females (x̄ = 5.1 km). Dens in the mountains were excavations into sloping ground (74%), or natural caves (26%), using rocks as the primary stabilizing structure (47%). Resource selection functions (RSF) revealed that mountain grizzly bears selected dens in alpine habitats at mid-to-upper elevations. Plateau bears mainly excavated dens under the base of trees (90%), where roots stabilized material (80%). These dens primarily were located in older-aged forest stands ranging from 45–99 years (40%) or >100 years (50%); RSFs further revealed that grizzly bears on the plateau selected stands with tall trees. Plateau dens also were located away from roads, possibly because of less disturbance and because older trees were farther from roads.

Highways are one of the leading causes of wildlife habitat fragmentation and may particularly affect wide-ranging species, such as American black bears (Ursus americanus). We initiated a research project in 2000 to determine potential effects of a 4-lane highway on black bear ecology in Washington County, North Carolina. The research design included a treatment area (highway construction) and a control area and a pre- and post-construction phase. We used data from the pre-construction phase to determine whether we could detect scale dependency or directionality among allele occurrence patterns using geostatistics. Detection of such patterns could provide a powerful tool to measure the effects of landscape fragmentation on gene flow. We sampled DNA from roots of black bear hair at 70 hair-sampling sites on each study area for 7 weeks during fall of 2000. We used microsatellite analysis based on 10 loci to determine unique multi-locus genotypes. We examined all alleles sampled at ≥25 sites on each study area and mapped their presence or absence at each hair-sample site. We calculated semivariograms, which measure the strength of statistical correlation as a function of distance, and adjusted them for anisotropy to determine the maximum direction of spatial continuity. We then calculated the mean direction of spatial continuity for all examined alleles. The mean direction of allele frequency variation was 118.3° (SE = 8.5) on the treatment area and 172.3° (SE = 6.0) on the control area. Rayleigh's tests showed that these directions differed from random distributions (P = 0.028 and P < 0.001, respectively), indicating consistent directional patterns for the alleles we examined in each area. Despite the small spatial scale of our study (approximately 11,000 ha for each study area), we observed distinct and consistent patterns of allele occurrence, suggesting different directions of gene flow between the study areas. These directions seemed to coincide with the primary orientation of the best habitat areas. Furthermore, the patterns we observed suggest directions of potential source populations beyond the 2 study areas. Indeed, nearby areas classified as core black bear habitat exist in the directions indicated by our analysis. Geostatistical analysis of allele occurrence patterns may provide a useful technique to identify potential barriers to gene flow among bear populations.

The Prudhoe Bay region of northern Alaska has large oil fields and hunting on adjacent lands, and there are concerns about potential effects on grizzly bears (Ursus arctos) in this region. Because effects on grizzly bear populations may include loss of genetic variation, we assessed the genetic variation and family relationships among grizzly bears in this region as part of a long-term research and monitoring project. We determined genotypes at 14 microsatellite DNA loci for 78 bears from the Prudhoe Bay region from samples collected 1990–2002. The genetic data identified one or both potential parents of 33 offspring. Potential parent–offspring and siblings had pair-wise relatedness indices of approximately 0.5, as expected. The entire sample of related and unrelated bears in the Prudhoe Bay region had a mean pair-wise relatedness index of approximately zero. Approximately 5.3% of the bears had relatedness indices within the range of first-order relatives (parent–offspring or siblings). Genetic differentiation is low (F_st = 0.0225) among the bears in the Prudhoe Bay region and neighboring areas of the western Brooks Range and the Arctic National Wildlife Refuge. Bears in the Prudhoe Bay region have a high level of genetic variation relative to some other areas in North America. High genetic variation and low relatedness among individual bears in the Prudhoe Bay region are probably maintained by a stable population size with gene flow across the North Slope of Alaska. Our data indicate that reduction of genetic variation in the grizzly bears in the Prudhoe Bay region is not presently a management concern.

Effective management of American black bears (Ursus americanus) requires an understanding of population demographics. In 2002, we obtained DNA from hair collected at barbed-wire traps to estimate black bear population size and study population genetics on Stockton (4,069 ha) and Sand (1,193 ha) islands at Apostle Islands National Lakeshore (AINL), Wisconsin. Hair samples also were collected from 2 nuisance bears on Oak Island. We analyzed 372 hair samples from Stockton and Sand islands collected on 4 occasions at about 14-day intervals. Genetic analysis of 6 microsatellite DNA markers resulted in 71 captures of 26 individuals on Stockton Island and 13 captures of 6 individuals on Sand Island. The estimated bear populations on Stockton and Sand islands were 26 (SE = 0.54, 95% CI [confidence interval] = 26–26) and 6 (SE = 0.60, 95% CI = 6–7) individuals, respectively. The estimated density on Stockton Island was 0.64 bears/km² and on Sand Island was 0.50 bears/km². Genetic variation within both island populations was higher (mean H_E ≥ 0.77) than could be maintained by populations of this size in isolation, suggesting substantial immigration from the mainland population occurred. Genetic assignment testing using log genotype likelihoods demonstrated sufficient variation between bear populations on Stockton and Sand islands to permit identification of natal origins. The 2 bears from Oak Island were genetically intermediate between Stockton and Sand islands. Islands within AINL contain small black bear populations of high density that are genetically distinct and apparently influenced by immigration from the mainland population.

To investigate feeding habits, carbon and nitrogen stable isotope ratios were measured in hair sampled from Asiatic black bears (Ursus thibetanus) inhabiting an alpine area, including the Northern Japanese Alps and the periphery of villages in Nagano Prefecture, in central Japan. Asiatic black bears in the Northern Japanese Alps are subject to little human influence, but in rural areas human encounters with bears seeking food in cornfields and garbage have become an issue that needs to be resolved. We investigated the feeding habits of bears by analyzing the isotopic changes along the entire length of hair samples. Rural bears, including nuisance bears, showed slightly higher δ¹⁵N and δ¹³C values than alpine bears, suggesting that rural nuisance bears may have greater access to anthropogenic food resources than their alpine counterparts. Hair samples were further examined by growth section analysis (GSA), in which sectioned samples from the root to the tip are used for isotopic analysis, to estimate feeding history during hair growth. Hairs of alpine bears exhibited low δ¹⁵N and δ¹³C values from the root to the tip, and the deviation was small. In contrast, hairs of rural bears, particularly of nuisance bears, showed large deviations in isotope values. One bear captured in a cornfield showed high δ¹³C values at its hair root. Another bear that thrived on garbage showed high δ¹⁵N and δ¹³C values at its hair root, similar to those of Japanese people. One captured bear, assumed to be part of nuisance activities, showed low δ¹⁵N and δ¹³C values from hair root to tip, suggesting that captured bears are not always the ones causing damage. By comparing and classifying GSA fluctuation patterns, we estimated the dependence of nuisance bears on human-related food sources. We expect these methods to provide relevant information for bear conservation and management programs.

The objective of this study was to define the conditions under which the body mass of polar bears (Ursus maritimus) can be estimated by morphometry with acceptable accuracy (high precision and low bias). Morphometric and body mass values from 563 polar bears captured and handled in southern Hudson Bay during 1984–86 and 2000–03 were analyzed to determine the effects of sample size and time on the accuracy of estimated body mass (EBM) and to determine the effect of using EBM versus observed body mass (OBM) to calculate body condition index (BCI) values. When sample size was small (≤25), variation around the difference between OBM and EBM was large. However, precision improved markedly with increasing sample size, stabilizing within approximately 3% for sample sizes ≥100. Morphometric–body mass relationships developed for southern Hudson Bay polar bears in the mid-1980s consistently overestimated body masses of bears handled since 2000 by approximately 4%, suggesting relationships within the population had changed over time (increased bias). This was verified by new prediction equations developed for each period that showed the EBM of polar bears captured in 2000–03 is 7–18% less than that for bears captured in the mid-1980s when morphometric values are held constant. Accuracy was reduced when EBM, instead of OBM, was used as a predictor variable for calculation of the BCI. This was caused by both loss of precision and increase in bias as a result of compounding the error associated with the EBM. Although body mass can be estimated accurately by morphometry under specific conditions, we recommend that investigators routinely weigh a proportion of bears captured per field season to ensure and maintain accuracy. The OBM values can be used to both verify the accuracy of EBM values and to calculate BCI values for representative bears.

Andean bears (Tremarctos ornatus) in Colombia face serious threats, including hunting, habitat loss, and bear–human interactions. Interactions are increasing, but data about these encounters are not consistently compiled. Likewise, bear management needs have not been evaluated. Solutions to these threats and needs are complex and will depend upon biological as well as cultural and political considerations. The objectives of this paper are to (1) quantify and characterize recent bear–human interactions in Colombia with respect to type and geographic distribution, and (2) identify conservation threats within the context of a general management program for Andean bears in Colombia. The study area is the entire range of the Andes Mountains in Colombia. The study is based on 43 written responses to surveys distributed during the early part of 1997 to local government officials that summarized 257 bear–human interactions at 94 localities (138 observations, 66 attacks or depredation, 34 hunting kills of bears, and 19 live captures or sale of parts). Interactions were reported most frequently in the Eastern Cordillera (108). This was explained by recent increases in the level of human activities in that region. We recommend (1) that the survey be continued to estimate bear–human interaction trends, and (2) that Colombian officials focus their bear conservation and management activities on the Western and Eastern Cordilleras, in areas where human density is lowest and the amount of natural forest is greatest, but where deforestation as a result of human colonization is increasing.

There is a long history of conflict in the western United States between humans and grizzly bears (Ursus arctos) involving agricultural attractants. However, little is known about the spatial dimensions of this conflict and the relative importance of different attractants. This study was undertaken to better understand the spatial and functional components of conflict between humans and grizzly bears on privately owned agricultural lands in Montana. Our investigations focused on spatial associations of rivers and creeks, livestock pastures, boneyards (livestock carcass dump sites), beehives, and grizzly bear habitat with reported human–grizzly bear conflicts during 1986–2001. We based our analysis on a survey of 61 of 64 livestock producers in our study in the Rocky Mountain East Front, Montana. With the assistance of livestock and honey producers, we mapped the locations of cattle and sheep pastures, boneyards, and beehives. We used density surface mapping to identify seasonal clusters of conflicts that we term conflict hotspots. Hotspots accounted for 75% of all conflicts and encompassed approximately 8% of the study area. We also differentiated chronic (4 or more years of conflicts) from non-chronic hotspots (fewer than 4 years of conflict). The 10 chronic hotpots accounted for 58% of all conflicts. Based on Monte Carlo simulations, we found that conflict locations were most strongly associated with rivers and creeks followed by sheep lambing areas and fall sheep pastures. Conflicts also were associated with cattle calving areas, spring cow–calf pastures, summer and fall cattle pastures, and boneyards. The Monte Carlo simulations indicated associations between conflict locations and unprotected beehives at specific analysis scales. Protected (fenced) beehives were less likely to experience conflicts than unprotected beehives. Conflicts occurred at a greater rate in riparian and wetland vegetation than would be expected. The majority of conflicts occurred in a small portion of the study area, where concentrations of attractants existed that overlapped with bear habitat. These hotspots should be the target of management and conservation efforts that focus on removing or protecting attractants using non-lethal techniques.

Interviews with farmers (1998–2000) in 5 communities along the edge of the Sungai Wain Protection Forest, East Kalimantan, Indonesian Borneo, indicated that crop damage caused by sun bears (Helarctos malayanus) was higher than normal following the 1997–98 El Niño Southern Oscillation Event. Widespread drought and forest fires reduced habitat and fruit availability for sun bears on the islands of Borneo and Sumatra. The main source of antagonism toward bears resulted from the damage they caused to stands of old coconut trees, which frequently killed the trees. This prompted farmers to seek removal of the bears. Bear damage to annual crops generally spurred a less hostile reaction. Experiments with metal sheeting affixed to the trunks of coconut trees to deter climbing by bears were successful, at least in the short term (<3 years). Inexpensive and easily applicable crop-protection devices such as this could help protect sun bears in the future, as increased human–bear conflicts are anticipated due to rapid human population growth, unabated forest destruction and fragmentation, and increased susceptibility of remaining forests to fires.