Grizzly bears reach weights of 180–680 kilograms (400–1,500
pounds) and stand a height of 2.44 m (8 feet) tall when standing
on its hind legs; the male is on average 1.8 times as heavy as
the female, an example of sexual dimorphism. This dimorphism
suggests that size is an important factor in the male's ability
to successfully compete for and attract breeding opportunities.
Their coloring ranges widely across geographic areas, from blond
to deep brown or black. These differences, once attributed to
subspeciation, are now thought to be primarily due to the
different environments these bears inhabit, particularly with
regard to diet and temperature.
The grizzly has a large hump over the shoulders which is a muscle mass used to power the forelimbs in digging. The head is large and round with a concave facial profile. In spite of their massive size, these bears can run at speeds of up to fifty-five kilometers per hour (thirty-five miles per hour).
Normally a solitary active animal, in coastal areas the grizzly congregates alongside streams and rivers during the salmon spawn. Every other year females (sows) produce one to four young (most commonly two) which are small and weigh only about 500 grams (one pound). Sows are very protective of their offspring.
The current range of the grizzly bear extends from Alaska, south through much of Western Canada, and into portions of the Northwestern United States including Idaho, Montana, Washington and Wyoming, extending as far south as Yellowstone and Grand Teton National Parks, but is most commonly found in Canada. Its original range also included much of the Great Plains and the Southwestern states, but it has been extirpated in most of those areas. The grizzly currently enjoys legal protection in the United States. However, it is expected that its repopulation of its former range will be a slow process, due equally to the ramifications of reintroducing such a large animal to areas which are prized for agriculture and livestock and also to the bear's slow reproductive habits (bears invest a good deal of time in raising young). There are currently about 60,000 wild grizzly bears currently located throughout North America. Brown bears (of which the grizzly bear is a subspecies) can live up to thirty years in the wild, though twenty to twenty-five is normal.
Bears have been known to prey on large mammals such as moose,
deer, sheep, caribou and even black bears. Grizzly bears will
feed on fish such as salmon, trout, and bass, and those with
access to a more protein-enriched diet in coastal areas
potentially grow larger than interior individuals. Grizzly bears
will readily scavenge food, behavior that can lead them into
conflict with other species, such as wolves and humans.
The grizzly bears that reside in the American northwest are not as large as Canadian or Alaskan sub-species Ursus arctos. This is due, in part, to the richness of their diet which in Yellowstone consists of whitebark pine nuts, roots, tubers, grasses, various rodents, army cutworm moths and scavenged carcasses, none of which match the fat content of the salmon available in Alaska and British Columbia. During early spring, as the bears emerge from their dens, elk and bison calves are actively sought. The bear will move in a zig-zag pattern, nose to the ground, hoping to find a meal.
In preparation for winter, bears will gain hundreds of kilograms of fat, during a period of hyperphagia, before going into a state of false hibernation. The bear will often wait for a substantial snowstorm before it enters its den. Presumably, this behavior lessens the chances that predators will be able to locate the den. The dens themselves are typically located at elevations above 6,000 feet on northern-facing slopes. There is some debate amongst professionals as to whether grizzly bears technically hibernate. Much of the debate revolves around body temperature and the ability of the bears to move around during hibernation on occasion. Grizzly bears have the ability to "partially" recycle their body wastes during this period. In some areas where food is plentiful year round, grizzly bears forgo hibernation altogether.
This Grizzly Bear Page is Copyright The Animal Web Guide © 2004 - 2009 Chuck Ayoub