Grizzly Bear
Grizzly bear
The grizzly bear (Ursus arctos ), a member of the family Ursidae, is the most widely distributed of all bear species . Although reduced from prehistoric times, its range today extends from Scandinavia to eastern Siberia, Syria to the Himalayan Mountains, and, in North America, from Alaska and northwest Canada into the northwestern portion of the lower 48 states. Even though the Russian, Alaskan, and Canadian populations remain fairly large, the grizzly bear population in the northwestern continental United States represents only about 1% of its former size of less than 200 years ago. Grizzly bears occupy a variety of habitats, but in North America they seem to prefer open areas including tundra , meadows, and coastlines. Before the arrival of Europeans on the continent, grizzlies were common on the Great Plains. Now they are found primarily in wilderness forests with open areas of moist meadows or grasslands .
Female grizzly bears vary in size from 200–450 lb (91–204 kg), whereas the much larger males can weigh up to 800 lb (363 kg). The largest individuals—from the coast of southern Alaska—weigh up to 1,720 lb (780 kg). Grizzly bears measure from 6.5–9 ft (2–2.75 m) tall when standing erect. To maintain these tremendous body sizes, grizzly bears must eat large amounts of food daily. They are omnivorous and are highly selective feeders. During the six or seven months spent outside their den, grizzly bears will consume up to 35 lb (16 kg) of food, chiefly vegetation, per day. They are particularly fond of tender, succulent vegetation, tubers, and berries, but also supplement their diet with insect grubs, small rodents, carrion, salmon , trout, young deer, and livestock, when the opportunity presents itself. In Alaska, along the McNeil River in particular, when the salmon are migrating upstream to spawn in July and August, it is not unusual to see congregations of dozens of grizzly bears, along the riverbank or in the river, catching and eating these large fish.
Grizzly bears breed during May or June, but implantation of the fertilized egg is delayed until late fall when the female retreats to her den in a self-made or natural cave, or a hollow tree. Two or three young are born in January,
February, or March, and are small (less than 1 lb/0.45 kg) and helpless. They remain in the den for three or four months before emerging, and stay with their mother for one and a half to four years. The age at which a female first reproduces, litter size, and years between litters are determined by nutrition, which induces females to establish foraging territories which exclude other females. These territories range from 10–75 mi2 (26–194 km2). Males tend to have larger ranges extending up to 400 mi2 (1,036 km2) and incorporate the territories of several females. Young females, however, often stay within the range of their mother for some time after leaving her care, and one case was reported of three generations of female grizzly bears living within the same range.
Grizzly bear populations have been decimated over much of their original range. Habitat destruction and hunting are the primary factors involved in their decline. The North American population, particularly in the lower 48 states, has been extremely hard hit. Grizzly bears numbered near 100,000 in the lower 48 states as little as 180 years ago, but, today, fewer than 1,000 remain on less than 2% of their original range. This population has been further fragmented into seven small, isolated populations in Washington, Idaho, Montana, Wyoming, and Colorado. This decline and fragmentation makes their potential for survival tenuous. The U. S. Fish and Wildlife Service considers the grizzly bear to be threatened in the lower 48 states.
Little has been done to protect this declining species in the lower 48 states. In 1999 it was agreed to begin slowly reintroducing grizzlies into the 1.2 million acre (49,000 ha) area of the Selway-Bitterroot Wilderness on the border of Idaho and Montana. Unfortunately, the project was put on hold as of 2001 due to unfounded fear of the animal. Habitat loss due to timbering, road building, and development in this region is still a major problem and will continue to impact these threatened populations of bears.
[Eugene C. Beckham ]
RESOURCES
BOOKS
Nowak, R. M., ed. Walker's Mammals of the World 5th ed. Baltimore: Johns Hopkins University Press, 1991.
PERIODICALS
"Interior Department Caves in to Grizzly Bear Scare." USA Today, August 6, 2001.
OTHER
Craighead Environmental Research Institute. [cited May 2002]. <http://www.grizzlybear.org>.
"New Grizzly Bear Recovery Plan: Bad News for Bears." Wild Forever, 1993.