The North American Grizzly Bear

Appearance

Range and Population

Brown bears are found in Asia, Europe, and North America, giving them the widest range of any bear species. They also previously inhabited North Africa. In North America, grizzly bears previously ranged from Alaska down to Mexico and as far east as the western shores of Hudson Bay; the species is now found in Alaska, south through much of western Canada, and into portions of the northwestern United States (including Washington, Idaho, Montana and Wyoming), extending as far south as Yellowstone and Grand Teton National Parks. 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. An article published in 1954 suggested they may be present in the tundra areas of the Ungava Peninsula and the northern tip of Labrador-Quebec. 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 has since significantly decreased due to hunting and habitat loss. In 2008, it was estimated there were 16,014 grizzly bears. A revised Grizzly bear count in 2012 for British Columbia was 15,075. Population estimates for British Columbia are based on hair-snagging, DNA-based inventories, mark-and-recapture, and a refined multiple regression model. In 2003, researchers from the University of Alberta spotted a grizzly on Melville Island in the high Arctic, which is the most northerly sighting ever documented. The Alaskan population of 30,000 individuals is the highest population of any province / state in North America. Populations in Alaska are densest along the coast, where food supplies such as salmon are more abundant. The Admiralty Island National Monument protects the densest population: 1,600 bears on a 1,600 square-mile island.

Biology

Grizzly bears hibernate for 5 to 7 months each year (except where the climate is warm, as the California grizzly did not hibernate). During this time, female grizzly bears give birth to their offspring, who then consume milk from their mother and gain strength for the remainder of the hibernation period. To prepare for hibernation, grizzlies must prepare a den, and consume an immense amount of food as they do not eat during hibernation. Grizzly bears do not defecate or urinate throughout the entire hibernation period. The male grizzly bear's hibernation ends in early to mid-March, while females emerge in April or early May. In preparation for winter, bears can gain approximately 180 kg (400 lb), during a period of hyperphagia, before going into hibernation. The bear often waits for a substantial snowstorm before it enters its den: such behavior lessens the chances predators will find the den. The dens are typically at elevations above 1,800 m (5,900 ft) on north-facing slopes. There is some debate amongst professionals as to whether grizzly bears technically hibernate: much of this debate revolves around body temperature and the ability of the bears to move around during hibernation on occasion. Grizzly bears can "partially" recycle their body wastes during this period. Although inland or Rocky Mountain grizzlies spend nearly half of their life in dens, coastal grizzlies with better access to food sources spend less time in dens. In some areas where food is very plentiful year round, grizzly bears skip hibernation altogether.