National Park

Grizzly Bears

Grizzly Bear Yellowstone by Kim Keating, USGS
Grizzly Bear Yellowstone photo by Kim Keating, USGS

Yellowstone retains one of the few wild populations of grizzly bears in the lower 48 states. The grizzly is a sub-species of the brown bear that entered North America from Asia 50,000 years ago. Plains tribes invoked this great bear’s awesome spirit in dance and ceremony and hunted it, too. The grizzly symbolizes wilderness. It is a magnificent predator at the top of the food chain. Grizzly bears are generally larger than black bears. Male grizzlies will average 400 to 600 pounds here, females 200 or 350 pounds. Both can sprint up to 35 or 40 mph. Rearing up on his hind legs, an adult may stand more than 8 feet tall. Since 1975 the grizzly has been protected as a threatened species under the Endangered Species Act. The grizzly bear requires great living space: a male grizzly in greater Yellowstone will range over 800 to 2,000 square miles; a female grizzly will range over 300 and 500 square miles. Yellowstone National Park’s boundaries can not contain the grizzly, and this has helped inspired multiagency cooperation and protecting the grizzly bear throughout our greater Yellowstone Ecosystem. Logging, mining, increasing human population, more home-building, and more recreation use threaten the grizzly bear’s future. Reducing and fragmenting grizzly habitat results in more conflicts between bears in humans and livestock, and in more bears getting hit by vehicles. Roads and fragmented habitat also facilitate poaching. Exotic organisms introduced by humans, such as fish-eating lake trout, invasive weed plants, and blister rust fungus on white pines, also threatened the grizzlies food supply. Because of their low reproduction rate, protection of breeding females is key to the grizzly bear’s recovery. Scientist radio collar grizzly bears in Yellowstone so they can monitor their location and behavior.


This post incorporates text from:

Yellowstone National Park Handbook 150. 2001.
National Park Service, Division of Publications.