Grizzly Bear Scientific name:Ursus arctos horribilis

Grizzly Bear
Scientific name:Ursus arctos horribilis
The grizzly bear is a North American subspecies of the brown bear.Dramatic gatherings of grizzly bears can be seen at prime Alaskan fishing spots when the salmon run upstream for summer spawning.
Range and habitat
The North American continent for the past million years, the grizzly bear has managed to outlive both the saber-toothed tiger and the mastodon. The Great Plains and the Rockies and Sierras of the American West have been reduced to a fraction of their former numbers.Grizzlies once lived in much of western North America and even roamed the Great Plains. Today, most grizzlies live in Alaska and Canada and those bears are found almost exclusively in some 10 million acres of Idaho, Montana and Wyoming.
Physical characteristics
The term "grizzly" refers to the white-tipped hairs that give it a frosty grizzled appearance, particularly those of the Rocky Mountains, and colors can range from a grayish color through yellow-brown to a dark-brown or nearly black coloration. The color depends largely on the grizzly bear habitat and also on the indigenous climate.
Most female grizzlies weigh 150–350 kg, while males weigh on average 230–450 kg. Newborn bears may weigh less than 500 grams.
Despite their enormous size, brown bears are extremely fast, having been clocked at speeds of 30 miles per hour (48 kilometers per hour).
Species
Subspecies
As of 2005, 16 subspecies have been recognized.
The subspecies have been listed as follows:
Ursus arctos arctos – Eurasian brown bear    Europe, Caucasus, Siberia (except the east) and Mongolia.    A predominantly dark colored (rarely light colored), moderately-sized subspecies with dark claws, the Eurasian browns occurring in Siberia are larger than their European counterparts, as they are hunted less. Where found in Europe, primarily a forest creature
Ursus arctos alascensis– Alaska   
Ursus arctos beringianus – Kamchatka brown bear (or Far Eastern brown bear)        Kamchatka Peninsula and Paramushir Island. This is a very large, dark colored form. Light colored forms are encountered less than in European-Siberian subspecies. The claws are dark.
Ursus arctos californicus – California golden bear (extinct)           
Ursus arctos collaris – East Siberian brown bear East Siberia from the Yenisei River to the Altai Mountains, also occurs in northern Mongolia.
Ursus arctos crowtheri – Atlas bear (extinct)           
Ursus arctos dalli       
Ursus arctos horribilis – Grizzly bear    Western Canada, Alaska, and the northwestern United States, historically existed in Great Plains   
Ursus arctos isabellinus – Himalayan brown bear Nepal, Pakistan, and Northern India    Having a reddish-brown or sandy coat color, this bear is smaller than most other brown bears found on the Asian continent.
Ursus arctos lasiotus – Ussuri brown bear (or Amur brown bear, black grizzly or horse bear) Russia: Southern Kuril Islands, Sakhalin, Maritime territory, and the Ussuri/Amur river region south of the Stanovoy Range, China: northeastern Heilongjiang, Japan: Hokkaidō.This bear is thought to be the ancestor of U. a. horribilis.
Ursus arctos middendorffi – Kodiak bear Kodiak, Afognak, Shuyak Islands (Alaska)    This is the largest subspecies of brown bear, with other coastal brown bears reaching as big.
Ursus arctos nelsoni – Mexican grizzly bear (extinct)    Northern Mexico, including Chihuahua, Coahuila, and Sonora, southwestern United States including southern ranges of Texas, Arizona, and New Mexico.   
Ursus arctos pruinosus – Tibetan blue bear Western China and Tibet.
Ursus arctos sitkensis – Baranof Island Appearing to be more closely related to the polar bear than to other brown bears.
Ursus arctos stikeenensis           
Ursus arctos syriacus – Syrian brown bear Occurs in the trans-Caucasus, Syria, Iraq,Turkey (Asia Minor), Iran, Afghanistan, western Himalayas and the Pamir-Alai and Tien Shan mountains, probable historical presence in Israel.
Hunting and diet
Although grizzlies are of the order Carnivora and have the digestive system of carnivores, they are normally omnivores, since their diet consists 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 protein-enriched diet in coastal areas potentially grow larger than interior individuals. Grizzly bears also readily scavenge food on carrion left behind by other animals.
The grizzly bear is omnivorous, eating anything from fish, honey and ants to beached whales. They also feed on dead game and other carrion. On rare occasions they kill elk and dig out ground squirrels and foxes.
Reproduction
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.The grizzly bear females do not become pregnant immediately because bears have developed a procedure called delayed implantation. 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.
At birth, the grizzly is blind and toothless and weights about 500 grams.
Predatory
Adult brown bears are powerful, top-of-the-food chain predators, . They can be dangerous to humans, particularly if surprised or if a person gets between a mother bear and her cubs.
Human are the only predators.
Life expectancy
Its Life span About 20 to 30 years.