An adult female weighs from 250 to 350 pounds, while a male reaches 400 to 600 pounds. In Idaho and Montana, grizzlies breed from May through July, with most activity in June. They hibernate from November through April. Young born in January during hibernation nurse for almost one year. Cubs usually stay with their mother for two years, then leave to establish their own home range.
Grizzly bears require a large area for movement and food searches.
The grizzly bear is an omnivore that feeds on berries, whitebark pine nuts, dead animals, bulbs, roots, grasses, and insects. The U.S. Fish and Wildlife Service is the principal Federal agency responsible for conserving, protecting and enhancing fish, wildlife and plants and their habitats for the continuing benefit of the American people. The agency enforces Federal wildlife laws, administers the Endangered Species Act, manages migratory bird populations, restores nationally significant fisheries, conserves and restores wildlife habitat such as wetlands, and helps foreign governments with their conservation efforts. It also oversees the Federal Aid program that distributes hundreds of millions of dollars in excise taxes on fishing and hunting equipment to state fish and wildlife agencies.