BIO 203

Interactions with Other Species

     Except for mating and caring for their young, grizzly bears primarily lead solitary lives, but they are still considered to be the most social bear in North America (U.S. Fish and Wildlife Service, 2000). They usually hibernate for 5 to 8 months out of the year, so they do not have much time during the year to interact. They only really interact with each other when they are breeding or when the mothers are raising their young cubs. The cubs usually stay with their mothers for about 2 to 3 years before they go off on their own (MacDonald, n.d.).
    Grizzly bears are not territorial and will roam anywhere from 50 to 500 square miles. They usually travel to the areas where there is an abundance of food. They spend most of their lives simply searching for food and eating. Grizzlies are considered to be omnivores because they are hunters that eat meat such as elk, white tail deer, moose, caribou, bison calves, ants, trout, and salmon. They also forage for berries such as salmonberries and other plants. Even though they are such massive animals, grizzly bears tend to feed on smaller things such as clover, dandelion, whitebark, limber pinenuts, cow parsnip, grasses, roots, bulbs, insects, insect nests, starchy tubers, and nuts. They usually search for foods that they can find easily and quickly (Silverstein et al., 1998).
    Adult grizzly bears are at the top of their food chain chain (U.S. Fish and Wildlife Service, 2000). They have no real predators besides humans and other bears, even though they try to avoid them at all costs. Humans are not only the biggest predators of grizzlies because humans hunt them, but also because the increasing human population is causing the grizzly bears' habitat to be taken over (Horejsi 2008). As detailed on the Habitat and Geography page of this website, grizzlies and humans are often in close proximity due to their converging territories.

U.S Department of Transportation

     Grizzlies are very protective and will attack anything that seems to be a threat to their cubs or food. Grizzly bear cubs, on the other hand, are often preyed upon by mountain lions, wolves and other bears. Around 1900 the grizzly bear population started to decline, and by 1975 they had become protected under the Endangered Species Act (Brown Bear, n.d.). Today the grizzly bear population in the lower United States is around 1,200 and they are considered to be a threatened species. In Alaska however, there are estimated to be around 30,000 grizzlies. Grizzly bears are still being illegally hunted today by farmers because they damage their crops. They are also being killed by poachers for their teeth, claws, hide, and internal organs. Grizzly bears' internal organs, especially their gallbladders are sold in the Asian medical market because the bile it produces is used in medicines (MacDonald, n.d.). 

Life History and Reproduction