Food habits of Yellowstone grizzly bears, 1977–1987

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.

Temporal changes in the population density and diet of brown bears in eastern Hokkaido, Japan

“…The sizeable presence of herbaceous plants in the early summer of 1978, and from spring to early summer of 1998-2000, corroborates earlier studies of Hokkaido brown bears (Aoi 1985;Ohdachi and Aoi 1987;Yamanaka and Aoi 1988;Sato 2002) and those of other regions of the world (Cicnjak et al 1987;Mattson et al 1991;Clevenger et al 1992;Elgmork and Kaasa 1992;McLellan and Hovey 1995;Persson et al 2001).…”

“…In contrast, ripened corn is available only from late August to early September. The large amount of berries, acorns, and nuts in the bear diets in the fall of 1998-2000 corresponds with other areas of Hokkaido (Aoi 1985;Ohdachi and Aoi 1987;Yamanaka and Aoi 1988;Sato 2002), as well as with other areas of the world (Cicnjak et al 1987;Mattson et al 1991;Clevenger et al 1992;Elgmork and Kaasa 1992;McLellan and Hovey 1995).…”

Predormancy omnivory in European cave bears evidenced by a dental microwear analysis of Ursus spelaeus from Goyet, Belgium

“…This gain results from a balance between energy expenditure, intake, foraging time, and fat accumulation, depending primarily on availability, foraging efficiency, body size, and condition (45,46). As a result, a mixed diet is the most common one in extant bears in the fall, which may include one dominant item such as terrestrial vertebrates (mostly ungulates and rodents) (47-50), insects (especially ants) (51), roots (52), berries (50,52), or hard mast (53). Dietary specialization, based on a single food source, in extant bears is unlikely in the fall.…”

Animal Habitat Quality and Ecosystem Functioning: Exploring Seasonal Patterns Using Ndvi

“…However, pulses in primary production not only influence animal behavior during the season of low energy availability but also may control the habitat quality for reproduction. For example, in mammals, such as the brown bear, adapted to low resource availability during winter and spring (Hellgren 1998), pregnant females do not feed for a long period of the year; thus breeding success depends critically on a pulse in energy availability for fat storage during the hyperphagia period in summer and fall (Mattson et al 1991, Craighead et al 1995, Hissa 1997, Inman and Pelton 2002.…”