Grizzly Bears That Kill Livestock

Abstract

Thirty-seven grizzly bears (Ursus arctos) equipped with radio transmitters were monitored in and around Yellowstone National Park between 1974 and 1979. Ten of the bears were known or suspected to kill livestock; 3 preyed on cattle, 6 on sheep, and 1 on both. Bears that killed livestock ranged widely in and out of Yellowstone Park and normally exhibited foraging habits similar to those of other bears. All subadult and adult bears known to have the opportunity killed sheep. Most bears that came into contact with cattle did not make kills. All known cattle killers were adult bears, while 4 sheep killers were subadults. Sheep grazing should be reduced as much as possible on grizzly range, and cattle grazing allowed only if owners are willing to absorb predation losses. Int. Conf Bear Res. and Manage. 5:186-190 Investigations of grizzly bear ecology in and around Yellowstone National Park were begun by an interagency team in 1973. The relationship between grizzly bears and livestock on national forests was investigated as a subproject during the years 1975-1979. Information on grizzly bear-livestock relation? ships was scarce. Hubbard and Harris (1960) published a popular account of historical inci? dents. Sarber (unpubl. rep., Alaska Coop. Wildl. Res. Unit, 1939) investigated cases of bears preying on cattle and found that many cattle died of other causes. Eide (1965) concluded that brown bears were an effective predator on cattle on Ko? diak Island. Murie (1948) documented cases of grizzly bear predation on cattle in the southern portion of our study area and expressed concern about the effects of a general predator control policy on the grizzly bear population. Data on movements and home ranges of the Yellowstone grizzly showed that they are very mobile and range widely throughout Yellowstone National Park and surrounding forests (Craighead 1980, Knight et al., 1976 Annual Rep. Interagen? cy Study Team, Yellowstone grizzly bear investi? gations, 1977, Blanchard and Knight 1980). If, as a result of this mobility, bears were killing livestock and in return being killed by stockmen, the entire population could be affected. This pa? per reports our findings on grizzly bear-livestock relationships. The study area centered around Yellowstone National Park and included portions of Wyoming, Idaho, and Montana. Some of this area outside 1 Present address: Colville Confederated Tribes, P.O. Box 150, Nespelem, WA 99155. of the park was subjected to livestock grazing (Fig. 1). A complete description of the vegeta? tion and physiography of the area was given by Knight et al. (1976 Annual Rep. Interagency Study Team, Yellowstone grizzly bear investiga? tions, 1977). We wish to acknowledge the assis? tance of Mr. Ross Davis and Mr. William Enget, both sheepmen from St. Anthony, Idaho. Sever? al sheepherders and cattle association riders con? tributed information and assistance, although sometimes unwittingly. Personnel of the Bridger Teton, Gallatin, Shoshone, and Targhee National Forests were cooperative and gave assistance when needed. Mr. Tom Toman, Wyoming Game and Fish Commission, was very cooperative as were all personnel from the State University, and Mr. Randall Hall, Supervisor, Shoshone National Forest, have reviewed the manuscript.