Range and Diet of Grizzly Bear
Brown bears are found in Asia, Europe and North America, giving them one of the widest ranges of bear species. The ancestors of the grizzly bear originated in Eurasia and traveled to North America approximately 50,000 years ago. This is a very recent event in evolutionary time, causing the North American grizzly bear to be very similar to the brown bears inhabiting Europe and Asia. In North America, grizzly bears previously ranged from Alaska to Mexico and as far east as the Hudson Bay area. In North America, the species is now found only in 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. There may still be a small population in Colorado in the southern San Juan Mountains. In September 2007 a hunter produced evidence of grizzly bear rehabilitation in the Selway-Bitterroot ecosystem, in Idaho and western Montana, by killing a male grizzly bear. 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 bear also appears on the Flag of California, though they are extinct in the state, the last one having been shot in 1922. In Canada there are approximately 25,000 grizzly bears occupying British Columbia, Alberta, the Yukon, the Northwest Territories, Nunavut and the northern part of Manitoba. Combining Canada and the United States, grizzly bears inhabit approximately half the area of their historical range. In British Columbia, grizzly bears inhabit approximately 90% of their original territory. There were approximately 25,000 grizzly bears in British Columbia when the European settlers arrived. However, population size significantly decreased due to hunting and habitat loss. In 2008 it was estimated that there were 16,014 grizzly bears. Population estimates for British Columbia are based on Hair-Snagging, DNA-based inventories, Mark-Recapture and a refined Multiple Regression model. Other provinces and the United States may use a combination of different methods for population estimates. Therefore it is difficult to say precisely what methods were used to produce total population estimates for Canada and North America as they were likely developed from a variety of different studies. The grizzly bear currently has legal protection in Mexico, European countries, some areas of Canada and in the United States.
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.
Diet
Although grizzlies are of the order Carnivora and have the digestive system of carnivores, they are actually omnivores, since their diet consists of both plants and animals. They have been known to prey on large mammals, when available, such as moose, deer, sheep, elk, bison, caribou and even black bears. Grizzly bears 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 also readily scavenge food, on carrion left behind by other animals.
The grizzly bears that reside in the American Rocky Mountains are not as large as Canadian or Alaskan grizzlies. This is due, in part, to the richness of their diet, which in Yellowstone consists mostly of whitebark pine nuts, as well as roots, tubers, grasses, various rodents, army cutworm moths and scavenged carcasses. None of these, however, match the fat content of the salmon available in Alaska and British Columbia.
Plants make up approximately 80%–90% of a grizzly bears’ diet. Various berries make up a large portion of this. These can include blueberries (Vaccinium cyanococcus), blackberries (Rubus fruticosus), salmon berries (Rubus spectabilis), cranberries (Vaccinium oxycoccus), buffalo berries (Shepherdia argentea), and huckleberries (Vaccinium parvifolium), depending on the environment. Insects such as ladybugs, ants and bees are also eaten, but only if they are available in large quantities. At low quantities, the energy gained is not worth the foraging energy output. When food is abundant, grizzly bears will feed in groups, foraging together. For example, many grizzly bears will visit meadows right after there has been an avalanche or glacier slide. This is due to an influx of legumes, such as Hedysarum, which the grizzlies consume in massive amounts. When food sources become scarcer, however, they separate once again.
In preparation for winter, bears can gain approximately 400 lb (180 kg), during a period of hyperphagia, before going into a state of false hibernation. The bear often waits for a substantial snowstorm before it enters its den, such behavior lessening the chances that predators will be able to locate the den. The dens themselves are typically located at elevations above 6,000 feet (1,800 m) 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 skip hibernation altogether.