grizzly bears
The grizzly bear (Ursus arctos ssp.) is any North American subspecies of brown bear, including the mainland grizzly (Ursus arctos horribilis), Kodiak bear (U. a. middendorffi), peninsular grizzly (U. a. gyas), and the recently extinct California grizzly (U. a. californicus†)[1][2] and Mexican grizzly bear (U. a. nelsoni†). Specialists sometimes call the grizzly the North American brown bearbecause the grizzly and the brown bear are one species on two continents.[1] 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.[3][4][5]
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.[1] Except for females with cubs,[6] 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)[7] which are small and weigh only about 500 grams (1 lb) at birth. A sow is protective of her offspring and will attack if she thinks she or her cubs are threatened.The ancestors of the grizzly bear subspecies were brown bears originating in Eurasia that traveled to North America approximately 50,000 years ago.[9] This is a very recent event, on an evolutionary timescale, causing the North American grizzly bear to be very similar to brown bears inhabiting Siberia and northeast Asia. The closest Eurasian subspecies to the grizzly bears are believed to be the Ussuri brown bear(U. a. lasiotus) for mainland grizzlies and the Kamchatka brown bear (U. a. beringianus) for the coastal Alaskan and Kodiak bears which arrived in North America shortly before the Bering land bridge flooded.
When it received its scientific name in 1815, the grizzly was classified as a separate species from all other bears. However, modern genetic testing reveals the grizzly to be a subspecies of the brown bear (Ursus arctos). So in Eurasia, it is the "brown bear"; in North America, it is the "grizzly".
In other words, the grizzly and the brown bear are one species on two continents. Currently, Rausch and others classify three subspecies of the new "North American brown bear":U. a. horribilis, middendorffi, and gyas. But more recent studies of mtDNA suggest that this three-fold division of living grizzlies needs revision. Further testing of Y-chromosomes is required to yield an accurate new taxonomy with different subspecies.[1]
Coastal grizzlies, often referred to by the popular but geographically redundant synonym of "brown bear" or "Alaskan brown bear" are larger and darker than inland grizzlies, which is why they, too, were considered a different species from grizzlies. Kodiak grizzly bears were also at one time considered distinct. Thus, at one time there were five different "species" of brown bear, including three in North America
