Grizzly Bears (Ursus arctos horribilis)
The grizzly bear is the second largest land carnivore in North America. It has a strong, heavy body with an average length of 1.8 metres from nose to tail. It is distinguished from other bears by the large shoulder hump that supports its massive front legs, its extremely long front claws and the concave facial profile of its large head. The grizzly bear’s fur is usually darkish brown, but can vary from ivory yellow to black. It has long hairs on its head and shoulders that often have white tips and give the bear the “grizzled” appearance from which it derives its name. Its legs and feet tend to be even darker in colour.
Although grizzlies are carnivores and have the digestive system of carnivores, they are normally omnivores: their diets consist 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 protien-enriched diet in coastal areas potentially grow larger than inland individuals. Grizzly bears also readily scavenge food or carrion left behind by other animals.
Like most bears there is a large variation in size and weight depending on where they are found in North America. Most adult female grizzlies weigh 130–200 kg (290–440 lb), while adult males weigh on average 180–360 kg (400–790 lb). The average total length in this subspecies is 198 cm (6.50 ft), with an average shoulder height of 102 cm (3.35 ft) and hindfoot length of 28 cm (11 in). In the Yukon River area, mature female grizzlies can weigh as little as 100 kg (220 lb). One study found that the average weight for an inland male grizzly was around 270 kg (600 lb) and the average weight for a coastal male was around 408 kg (900 lb). For a female, these average weights would be 136 kg (300 lb) inland and 227 kg (500 lb) coastal, respectively. On the other hand, an occasional huge male grizzly has been recorded which greatly exceeds ordinary size, with weights reported up to 680 kg (1,500 lb). A large coastal male of this size may stand up to 3 m (10 feet) tall on its hind legs and be up to 5 ft (1.5 m) at the shoulder.
In North America, grizzly bears previously ranged from Alaska to Mexico and as far east as the western shores of Hudson Bay. 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. Only about 1,500 grizzlies are left in the lower 48 states of the US.
Grizzly bears have one of the lowest reproductive rates of all terrestrial mammals in North America. This is due to numerous ecological factors. Grizzly bears do not reach sexual maturity until they are at least five years old. Once mated with a male in the summer, the female delays embryo implantation until hibernation, during which miscarriage can occur if the female does not receive the proper nutrients and caloric intake. On average, females produce two cubs in a litter and the mother cares for the cubs for up to two years, during which the mother will not mate. Once the young leave or are killed, females may not produce another litter for three or more years, depending on environmental conditions. Male grizzly bears have large territories, up to 4,000 km2 (1,500 sq mi), making finding a female scent difficult in such low population densities.
References: Wikipedia, Canadian Geographic