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Little is known about the denning ecology of American black bears (Ursus americanus) in the Cascade Mountains of western Oregon. Extensive logging during the late 20th century altered the landscape significantly and may have affected the availability and quality of denning habitat. We visited 104 dens of 54 radiocollared bears during 1993–98 to document den-site characteristics and bear behavior in the Cascade Mountains of western Oregon. We also monitored bears in the spring and fall to estimate denning chronology. In addition, we randomly selected 5-ha quadrats to search for fungal activity and potential den sites. Eighty percent of dens we located were in trees that had cavities created by fungal activity. The remaining dens were located in rocky outcroppings and caves, under logs, or on the ground. We found no selection of dens based on micro- or macro aspect, elevation, or slope. Bears denned more than expected in mature timber with trees that averaged >50.8 cm diameter at breast height (dbh). Mean den entry date for bears in our study was November 20, and mean den emergence date was April 15. Pregnant females entered dens earlier and emerged later than barren females, females with yearlings, and all male age classes. Bears were more likely to abandon dens at lower elevations with little snow accumulation and less secure den structures. Fungal activity was randomly distributed throughout the study area. Fifty-one potential tree and log den structures were found in 27 of 64 quadrats we sampled. This information can help federal and state foresters schedule and design management activities within stands of timber containing denning habitat, aid wildlife managers in setting bear hunting seasons, and help timber cruisers and biologists detect and avoid disturbance of active dens.
Correction factors that relate the dry mass of food items consumed by brown bears (Ursus arctos) to the volume of the corresponding residue in the feces have been determined for various foods consumed by brown bears in North America, but the values of some important foods used by European populations remain unknown. We estimated the correction factors for wild cherries (Prunus avium), beechnuts (Fagus sylvatica), hazelnuts (Corylus avellana), and supplemental foods (corn, oats, and sugar beets) provided to bears in many areas of Europe. In 2011, we fed captive bears from the Warsaw Municipal Zoological Garden, Poland, with known amounts of these foods and measured the volume of their remains in their feces. Overall, correction factors for supplemental foods were lower than for natural foods. We recommend use of the values estimated in this study and further evaluations of correction factors for bear food items not yet assessed.
Identifying the relationships between human land use and wildlife habitat use is an essential component in any attempt to mitigate human–wildlife conflict and conserve imperilled wildlife populations. We studied habitat selection by Asiatic black bears (Ursus thibetanus) by employing a resource selection function (RSF), using GPS relocation data for 9 bears in 2008 and 2009. We focused on habitat selection in summer when human–bear conflicts are most frequent in the central Japanese Alps. Logistic regression indicated that bears were positively associated with red pine (Pinus densiflora) forest and regenerating lands and negatively associated with both larch (Larix leptolepis) and coniferous plantation. Almost all bears tended to select areas with steep slopes that were close to roads and rivers. An index of human–bear encounter risk, estimated using the predicted RSF map and road density, suggested that only 5.3% of the study area was secure habitat with low human access for bears. Selection by bears for red pine woodlands is one of the reasons for the prevalence of conflicts in summer. We recommend that wildlife managers exercise caution because lethal control of bears in the most frequently selected areas may have a serious effect on the population. Our study, as well as further spatially defined habitat research, can provide information crucial to the appropriate habitat management needed to conserve bears and mitigate conflict in the long term.
Opportunities for viewing grizzly bears (Ursus arctos) and American black bears (U. americanus) from roadways in Yellowstone National Park (YNP) have increased in recent years. Unlike the panhandling bears common prior to the 1970s, current viewing usually involves bears feeding on natural foods. We define roadside bear viewing opportunities that cause traffic congestion as “bear-jams.” We investigated characteristics of bear-jams and their frequency relative to whitebark pine (Pinus albicaulis) cone production, an important fall food for bears, during 1990–2004. We observed a difference in diel distribution of bear-jams between species (χ2 = 70.609, 4 df, P < 0.001) with the occurrence of grizzly bear-jams being more crepuscular. We found evidence for decreasing distances between bears and roadways and increasing durations of bears-jams. The annual proportion of bear-jams for both species occurring after the week of 13–19 August were 3–4 times higher during poor cone crop years than good. We suggest that native foods found in road corridors may be especially important to some individual bears during years exhibiting poor whitebark pine crops. We discuss management implications of threats to whitebark pine and increasing habituation of bears to people.
Predation on returning runs of adult salmon (Oncorhynchus spp.) can have a large influence on their spawning success. At McNeil River State Game Sanctuary (MRSGS), Alaska, brown bears (Ursus arctos) congregate in high numbers annually along the lower McNeil River to prey upon returning adult chum salmon (O. keta). Low chum salmon escapements into McNeil River since the late 1990s have been proposed as a potential factor contributing to concurrent declines in bear numbers. The objective of this study was to determine the extent of bear predation on chum salmon in McNeil River, especially on pre-spawning fish, and use those data to adjust the escapement goal for the river. In 2005 and 2006, 105 chum salmon were radiotagged at the river mouth and tracked to determine cause and location of death. Below the falls, predators consumed 99% of tagged fish, killing 59% of them before they spawned. Subsequently, the escapement goal was nearly doubled to account for this pre-spawning mortality and to ensure enough salmon to sustain both predators and prey. This approach to integrated fish and wildlife management at MRSGS can serve as a model for other systems where current salmon escapement goals may not account for pre-spawning mortality.
In 2007, Grand Teton National Park authorized construction of several paved, non-motorized pathways situated within existing road corridors, primarily designed for pedestrian and bicycle use. Construction of the first 13-km section was completed during 2008. The pathway resulted in direct loss of wildlife habitat, new human activities, and a wider zone of human use. We examined how these changes affected American black bear (Ursus americanus) movements, habitat use, activity, corridor crossings, and visibility to human visitors. Thirty (12F, 18M) bears, fitted with global positioning system (GPS) radiocollars, were monitored during 1–3 study periods: pre-pathway (2001–07), construction (2008), and pathway (2009–10). During 2009–10, we deployed 6 trail counters to document human use of the pathway. Counts of humans ranged from 0 to 148 detections/counter/hour. Mean counts peaked during mid-summer (15 Jun–30 Aug) and during midday (1100–1600 hrs). Bears did not shift their home ranges in response to human use of the pathway, nor did they reduce their frequency of corridor crossings. Instead, bears altered the way they used the areas near the corridor. Across the study periods, bears showed greater selection for steep slopes and for areas farther from the corridor, and they were increasingly likely to cross the corridor in areas providing vegetative cover. Near the corridor, bears decreased their activity by approximately 35% during midday and increased their activity by about 10% during morning and evening. Proportion of corridor crossings occurring at night also increased 20–40%. These behavioral changes allowed bears to continue using areas near the corridor while reducing encounter rates with humans on the pathway. However, the observed shift of activity toward morning, evening, and night may increase the likelihood that human–bear encounters would occur during the low light conditions of dawn and dusk and increase the probability of vehicle collisions.
Human–wildlife conflict challenges wildlife managers globally. In Japan, the Asiatic black bear (Ursus thibetanus) is listed as a vulnerable species under IUCN's Red List of Threatened Species. In Hyogo Prefecture it is listed as an endangered local population, but bears are considered a nuisance because of agricultural damage and occasional human casualties. The bear population in the prefecture is increasing, and human–bear conflicts are also increasing. We conducted a mail survey in July 2010 of residents in 58 villages (n = 2,315) to examine their perceptions of risks, government performance, and acceptance of bears. Survey response was 52% (n = 1,210). Eighty-one percent of respondents reported that risks from bears had increased and 83% believed there were too many bears around their village. Risk perception was negatively correlated with acceptance capacity of bears. In contrast to our prediction, increased agreement that government provided necessary information was associated with greater perceived risk from bears. However, agreement that the government listened to people's concerns was a significant factor predicting respondents' behavior in taking preventive actions such as reporting bear sightings. This study suggests that, by providing problem-prevention information and adequate opportunities for residents to voice their concerns, government officials may be able to increase residents' confidence in their ability to prevent bear-related problems and their tolerance of interactions with bears. If widespread, such outcomes would improve conservation of bears of Japan.
Three species of bears occur in Bangladesh, but most populations have declined to very low numbers or disappeared completely. No systematic surveys have been conducted to determine status and distribution of the remnant populations. Therefore, we conducted surveys at 87 sites with historical records of bears. Footprints, claw marks, and other signs were used to identify bears to species level. In addition, semi-structured interviews were carried out targeting local community members to determine the status of bears. Bear signs were documented in 26 sites in the northeast, 42 sites in the southeast, and 1 site in the north-central region of Bangladesh. With the exception of a single sign that presumably came from a sun bear (Helarctos malayanus), all were identified as Asiatic black bear (Ursus thibetanus). Additionally, we documented one recent occurrence of a captive sun bear captured in the southeastern region of Bangladesh not covered in our survey. We conclude that the sloth bear (Melursus ursinus) is possibly extinct in Bangladesh. Although Asiatic black bear signs were recorded from many sites, the populations are scattered and likely to be very low in numbers. Similarly, the single confirmed record of sun bear suggests that the species is possibly a vagrant from adjoining Indian populations and the populations in Bangladesh are not self-sustaining. Deforestation and hunting are major threats to bears in Bangladesh. Unless urgent conservation measures are taken and degraded forest areas are restored, we suspect that the Asiatic black bear may soon become extinct in Bangladesh.
We assessed American black bear (Ursus americanus) harvest trends, generally, and black bear harvest over bait, specifically, in Alaska from 1992 to 2010 at 3 spatial scales: statewide, on drainages adjacent to and including National Park Service (NPS) units, and on NPS lands. Statewide, black bear reported harvest increased by an average of 93 bears/year, and harvest over bait increased by an average of 21 bears/year over this period. Harvest over bait increased by 4.3% (SE = 4.3) annually, and harvest by other methods increased by 3.9%/year (SE = 3.1). The proportion of females harvested over bait was 30.9% compared to 26.4% by other methods. Harvest increased around Lake Clark National Park and Preserve, while other units and adjacent lands had stable or decreasing harvest rates. Few bears were harvested using bait on NPS units (≤37 bears; <2 bears/year) with ≤34 (91.9%) of these bears harvested in Wrangell St. Elias National Park and Preserve. Only 3 bears were harvested over bait by rural Alaska residents from NPS lands from 1992 to 2010. Thus, little to no population-level effects arose from the practice of bear baiting on NPS lands. Rather, the complexity surrounding the practice of bear baiting is centered on the management goals of minimizing food-conditioning of bears, fostering public safety, preventing defense of life and property killing of individual bears, and maintaining natural processes and behaviors. We recommend application of the formal field of conservation ethics and argument analysis as one path forward in assessing policy on bear baiting on Alaskan NPS units and recommend that the issue of harvesting bears over bait on NPS lands not be falsely characterized as a conservation or population management issue.