Food habits of Yellowstone grizzly bears, 1977-1987
Canadian Journal of Zoology
By: David J. Mattson, Bonnie M. Blanchard, and Richard R. Knight
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Abstract
Food habits of grizzly bears were studied for 11 years in the Yellowstone area of Wyoming, Montana, and Idaho by analyzing scats. Ungulate remains constituted a major portion of early-season scats, graminoids of May and June scats, and whitebark pine seeds of late-season scats. Berries composed a minor portion of scats during all months. The diet varied most among years during May, September, and October, and was most diverse during August. Defecation rates peaked in July and were low in April through June. Among-years differences in scat content were substantial; estimates of average scat composition took 4-6 years to stabilize. Major trends in diet were evident and reflected long-term variation. We suggest that long-term studies are necessary to adequately document bears' food habits in variable environments; the Yellowstone grizzly bears' diet varied with seasonal and yearly availability of high-quality foods, lack of berries and large fluctuations in the size of pine seed crops were major factors limiting bear density in the Yellowstone area, and the availability of edible human refuse buffered the limitations imposed by inadequate berry and pine seed crops prior to the 1970s.
Suggested Citation
Mattson, D.J., Blanchard, B.M., Knight, R.R., 1990, Food habits of Yellowstone grizzly bears, 1977-1987: Canadian Journal of Zoology, v. 69, p. 1619-1629.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Food habits of Yellowstone grizzly bears, 1977-1987 |
| Series title | Canadian Journal of Zoology |
| Volume | 69 |
| Year Published | 1990 |
| Language | English |
| Publisher | Canadian Science Publishing |
| Description | 11 p. |
| First page | 1619 |
| Last page | 1629 |
| Country | United States |
| State | Idaho, Montana, Wyoming |
| Other Geospatial | Yellowstone National Park |