Craig Pass Closed for the Season; Mammoth to Norris Closed Sept. 14-30
The road linking West Thumb and Old Faithful is closed for the season—traffic should detour through West Thumb, Lake, and Canyon. The road from Mammoth to Norris is closed for two weeks—traffic should detour over Dunraven Pass. More »
Food Habits of Grizzly Bears and Black Bears in the Yellowstone Ecoystem
Bears are omnivores that have relatively unspecialized digestive systems similar to those of carnivores. The primary difference is that bears have an elongated digestive tract, an adaptation that allows bears more efficient digestion of vegetation than other carnivores (Herrero 1985). Unlike ruminants, bears do not have a cecum and can only poorly digest the structural components of plants (Mealey 1975). To compensate for inefficient digestion of cellulose, bears maximize the quality of vegetal food items ingested, typically foraging for plants in phenological stages of highest nutrient availability and digestibility (Herrero 1985).
The food habits of grizzly bears in Greater Yellowstone Ecosystem (GYE) have been described in detail by Knight et al. (1984) and Mattson et al. (1991). Overall, army cutworm moths, whitebark pine nuts, ungulates, and cutthroat trout are the highest quality food items available to grizzly bears in the GYE. These foods impart the greatest nutritive value in exchange for the least foraging effort (Craighead et al. 1995). Grizzly bear food habits are influenced by annual and seasonal variation in available foods.
Gunther, K.A., and R.A. Renkin. 1990. Grizzly bear predation on elk calves and other fauna of Yellowstone National Park. Int. Conf. Bear Res. And Manage. 8:329-334.
Herrero, S. 1978. A comparison of some features of the evolution, ecology and behavior of black and grizzly/brown bears. Carnivore 1(1):7-17. _____. 1985. Bear Attacks-Their Causes and Avoidance. Winchester Press, New Century Publishers, Inc., Piscataway, N.J. 287pp.
Knight, R.R., D.J. Mattson, and B.M. Blanchard. 1984. Movements and habitat use of the Yellowstone grizzly bear. U.S. Dep. Inter., Natl. Park Serv., Interagency Grizzly Bear Study Team. Unpubl. Rep. 177pp.
_____, B.M. Blanchard, and D.J. Mattson. 1988. Yellowstone Grizzly bear investigations: Annual report of the Interagency Grizzly Bear Study Team, 1987. U.S. Dep. Inter., Natl. Park Serv. 80pp.
Mattson, D.J., and C. Jonkel. 1990. Stone pines and bears. Pages 223-236 in Proceedings-Symposium on Whitebark Pine Ecosystems: Ecology and Management of a High-Mountain Resource, U.S. Dep. Agric., U.S. For. Serv. 386pp.
Mattson, D.J., B.M. Blanchard, and R.R. Knight. 1991. Food habits of Yellowstone grizzly bears, 1977-87. Can. J. Zool. 69:1619-1629.
Mattson, D.J., B.M. Blanchard, and R.R. Knight. 1992. Yellowstone grizzly bear mortality, human habituation, and whitebark pine seed crops. J. Wildl. Manage. 56:432-442.
Mattson, D.J. 1997. Use of Ungulates by Yellowstone grizzly bears Ursus arctos. Biol. Conserv. 81:161-177.
Mealay, S.P. 1975. The natural food habits of free-ranging grizzly bears in Yellowstone National Park, 1973-1974. M.S. Thesis, Montana State Univ., Bozeman. 158pp.
Reinhart, D.P. 1990. Grizzly bear habitat use on cutthroat trout spawning streams in tributaries of Yellowstone Lake. M.S. Thesis, Montana State Univ., Bozeman. 128pp.
Did You Know?
Yellowstone contains approximately one-half of the world’s hydrothermal features. There are over 10,000 hydrothermal features, including over 300 geysers, in the park.