The grizzly bear (Ursus arctos ssp.) is any North American subspecies of the brown bear, including the mainland grizzly (Ursus arctos horribilis), the Kodiak bear (U. a. middendorffi), the peninsular grizzly (U. a. gyas), and the recently extinct California grizzly (U. a. californicus†) and Mexican grizzly bear (U. a. nelsoni†). Specialists sometimes call the grizzly the North American brown bear because the grizzly and the brown bear are one species on two continents. It should not be confused with the black grizzly or Ussuri brown bear (U. a. lasiotus) which is another giant brown bear subspecies inhabiting Russia, Northern China, and Korea. In some places, the grizzly is nicknamed the silvertip bear for the silvery, grizzled sheen in its fur.
Since the mainland grizzly is so widespread, it is representative and archetypal for the whole subspecific group. Even so, classification is being revised along genetic lines. Except for females with cubs, grizzlies are normally solitary, active animals, but in coastal areas, grizzlies gather around streams, lakes, rivers, and ponds during the salmon spawn. Every other year, females (sows) produce one to four young (usually two) which are small and weigh only about 500 grams (1 lb). A sow is protective of her offspring and will attack if she thinks she or her cubs are threatened.
Most adult female grizzlies weigh 130–200 kg (290–440 lb), while adult males weigh on average 180–360 kg (400–790 lb). 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). Newborn bears may weigh less than 500 grams (1.1 lb). 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 kilograms (600 lb) and the average weight for a coastal male was around 408 kilograms (900 lb). For a female, these average weights would be 136 kilograms (300 lb) inland and 227 kilograms (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 metres (9.8 ft) tall on its hind legs and be up to 1.5 metres (4.9 ft) at the shoulder. Although variable from blond to nearly black, grizzly bear fur is typically brown in color with white tips. A pronounced hump appears on their shoulders; the hump is a good way to distinguish a black bear from a grizzly bear, as black bears do not have this hump.