Status, trend, and population dynamics of the Yellowstone grizzly bear.

Authors(s): C. Schwartz, M. Haroldson, C. Dickinson, S. Podruzny and C. Whitman

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Publication Date: 0000-00-00

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Abstract: Objectives To describe the population trend from threatened status to recovery and approximate stability. Findings and Status Status, trend, and population dynamics of the Yellowstone grizzly bear. Fifty-four individual grizzly bears were captured a total of 65 times during the 2000 field season in the Greater Yellowstone Area (GYA). Thirty-two captures were new individuals that had not been previously marked. Twenty-seven captures of 24 bears were the result of management trapping efforts. Twelve of these instances resulted in relocation of the nuisance bear(s); 5 management captures resulted in the removal of nuisance individual(s). A total of 1,039 aerial radio-locations were obtained from 84 individual grizzly bears radio-monitored during all, or a portion of the 2000 field season. Twenty-eight of the grizzly bears radio-monitored were adult females. Two rounds of observation flights were conducted as part of our effort to count unduplicated females with cubs-of-the-year and document distribution of females with young (cubs, yearlings, or 2-year-olds). The first round of flights began 5 June. Thirteen grizzly bears were observed in 10 groups during 47 hours of flying before we curtailed flights due to bad weather and poor bear sightability. The second round of flights began on 17 July. A total of 108 grizzly bears in 71 groups were observed during 79 hours of flying. Twenty-two females with young were observed during observation flights; 7 of these were initial observations of unduplicated females with cubs-of-the-year. Thirty-seven unduplicated females with cubs were identified during 2000. A total of 72 cubs were observed during the initial sightings of unduplicated females. Nine single cub litters, 21 litters of twins, and 7 litters of triplets were observed. Mean litter size was 1.9. Unduplicated females with cubs were observed in 14 of 18 Bear Management Units (BMU) within the grizzly bear recovery zone. Females with young were documented in all 18 BMUs. We documented 19 known, 1 probable, and 3 possible man-caused grizzly bear mortalities during 2000; 5 were management removals. Thirteen of the known and probable man-caused mortalities were related to big-game hunting activity within the GYA. Three known and 3 probable natural mortalities were documented. An additional 4 grizzly bears (3 known and 1 possible) that died from unknown causes were discovered. The IGBST trapping efforts were conducted between 20 April and 24 May 2000 in Bear Management Units 17 and 18 in Grand Teton National Park. A total of 5 grizzly bears and 2 black bears were captured. All grizzly bears and black bears were handled, instrumented with radio transmitters, and released on site. A total of 73 trap nights were monitored by IGBST and GRTE personnel. Yellowstone Grizzly Bear Investigations for 1995-1999 are now available at http://nrmsc.usgs.gov/research/igbst-home.htm The 2000 Annual Report will be available by mid summer 2001.

Keywords: Greater Yellowstone Ecosystem, Yellowstone National Park, Grand Teton National Park, Bridger-Teton National Forest, management, population, mortality, animal, mammal, bear, Ursidae, grizzly bear, Ursus arctos horribilis, radio collar, human activity, hunting