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

Authors(s): C. Schwartz

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Publication Date: 0000-00-00

Type: annual report

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Abstract: Objectives To describe the population trend from threatened status to recovery and approximate stability. Findings and Status These data include information collected by the Interagency Grizzly Bear Study Team (members include USGS-BRD, NPS, WYDGF, IDFG, MTDFWP, USFWS, USFS) for the entire Greater Yellowstone Ecosystem. Data obtained within GTNP is not broken out separately. Sixty-three individual grizzly bears were captured a total of 73 times during the 2001 field season in the Greater Yellowstone Ecosystem (GYE). Forty captures were new individuals that had not been previously marked. Thirty-two captures of 28 bears were the result of management trapping efforts. Fifteen of these instances resulted in relocation of the nuisance bear(s). A total of 933 aerial radio-locations were obtained from 82 individual grizzly bears radio-monitored during all, or a portion of the 2001 field season. Thirty-one 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 19 June. Seventy-nine grizzly bears were observed in 49 groups during 72 hours of flying. The second round of flights began on 17 July. A total of 171 grizzly bears in 120 groups were observed during 72 hours of flying. Thirty-seven females with young were observed during observation flights; 20 of these were initial observations of unduplicated females with cubs-of-the-year. Forty-two unduplicated females with cubs were identified during 2001. A total of 78 cubs were observed during the initial sightings of unduplicated females. Thirteen single cub litters, 22 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 (cubs, yearlings or 2-year-olds) were documented in all 18 BMUs. We documented 20 known and 1 probable human-caused grizzly bear mortalities in the GYE during 2001. Nineteen human-caused mortalities, including 6 adult females and 8 total females, occurred within the USFWS Recovery Zone and 10-mile perimeter. Sixteen losses were from management removals, including 4 bears that were initially translocated, but became involved in subsequent conflicts and were removed. Thirteen and 3 management removals occurred in Wyoming and Montana, respectively. Five natural (4 known and 1 probable) mortalities were documented. Six grizzly bears that died from unknown causes were documented during 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