Spatial variation in density of American black bears in northern Yellowstone National Park |
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Authors: | Nathaniel R. Bowersock Andrea R. Litt Michael A. Sawaya Kerry A. Gunther Frank T. van Manen |
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Affiliation: | 1. Department of Ecology, Montana State University, P.O. Box 173460, Bozeman, MT, 59717-3460 USA;2. Sinopah Wildlife Research Associates, Missoula, MT, 59804 USA;3. Bear Management Office, Yellowstone Center for Resources, Yellowstone National Park, P.O. Box 168, Yellowstone National Park, WY, 82190 USA;4. U.S. Geological Survey, Northern Rocky Mountain Science Center, Interagency Grizzly Bear Study Team, 2327 University Way, Suite 2, Bozeman, MT, 59715 USA |
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Abstract: | The quality and availability of resources are known to influence spatial patterns of animal density. In Yellowstone National Park, relationships between the availability of resources and the distribution of grizzly bears (Ursus arctos) have been explored but have yet to be examined in American black bears (Ursus americanus). We conducted non-invasive genetic sampling during 2017–2018 (mid-May to mid-July) and applied spatially explicit capture-recapture models to estimate density of black bears and examine associations with landscape features. In both years, density estimates were higher in forested vegetation communities, which provide food resources and thermal and security cover preferred by black bears, compared with non-forested areas. In 2017, density also varied by sex, with female densities being higher than males. Based on our estimates, the northern range of Yellowstone National Park supports one of the highest densities of black bears (20 black bears/100 km2) in the northern Rocky Mountains (6–12 black bears/100 km2 in other regions). Given these high densities, black bears could influence other wildlife populations more than previously thought, such as through displacement of sympatric predators from kills. Our study provides the first spatially explicit estimates of density for black bears within an ecosystem that contains the majority of North America's large mammal species. Our density estimates provide a baseline that can be used for future research and management decisions of black bears, including efforts to reduce human–bear conflicts. |
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Keywords: | abundance American black bear density non-invasive genetic sampling resource spatially explicit capture-recapture Ursus americanus Yellowstone National Park |
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