GRIZZLY BEAR

Grizzly bear (Ursus arctos) also called silvertip large North American brown bear of the family Ursidae. Grizzly bears, including the Alaskan brown bears, are usually considered to be races of a single species, Ursus arctos (see brown bear). More than 80 forms of grizzly bears have been described, most as distinct species but now generally treated as subspecies of U. arctos, or U. horribilis of some authors. Grizzlies once ranged over western North America from Mexico to Alaska. Their numbers are few in the United States and Mexico and are much reduced elsewhere. They are protected in national parks and in zoos; their natural habitat is northern, open regions. The 9 or 10 populations of Alaskan brown bears (sometimes separated as U. middendorffi, U. gyas, and others) are native to the coasts and offshore islands of Alaska. Both grizzly and Alaskan brown bears are massive animals with humped shoulders and an elevated forehead that contributes to a somewhat concave profile. The fur is brownish to buff, and the hairs are usually silver- or pale-tipped to give a grizzled effect. Large adult grizzlies may be about 2.5 m (8 feet) long and weigh about 410 kg (900 pounds). Adult Kodiak bears (U. a. middendorffi), the largest living land carnivore, may attain a length of more than 3 m and a weight of 780 kg. Omnivorous animals, grizzly and Alaskan brown bears feed on game, fish, berries, and occasionally even grass. They often cache food in shallow holes, and they dig readily and strongly in search of rodents. Methodical animals, they develop deeply rutted trails in which each passing bear treads in the footsteps of its predecessor. Bears living in the north retire to dens in winter. Cubs, usually twins, are born at this time of year after about 68 months' gestation; at birth, they weigh about 0.50.75 kg. Because of their bulk and long, straight claws, these bears rarely climb even as cubs. They are, however, surprisingly agile and can run as fast as 48 km (30 miles) per hour. Grizzlies have been known to attack humans without evident provocation. They are highly prized as big game and have been the subject of many North American Indian legends.