![]() ![]() If a female bear is unable to gain enough weight during the summer and fall, her body will tell her to not proceed with the pregnancy and the embryo will reabsorb. When a female grizzly becomes pregnant, the development of the embryo temporarily stops for several months, a process called “delayed implantation.” Delayed implantation is characteristic of all bear species and some other families of carnivores, including weasels and seals. Females can mate with more than one male during her breeding season. Grizzly bears begin to look for mates in the spring and early summer. Pregnant females are the first to enter dens in the fall followed by females with cubs solitary males enter dens the latest. Females with older cubs emerge earlier and solitary females and males are the first to exit dens in the spring. Females with newborn cubs are the last to leave their dens in the spring. Grizzly bear hibernation is not as deep of a sleep as some other hibernators, like bats or ground squirrels, and they will quickly wake up when disturbed. They don’t even go to the bathroom during this time. Pregnant females give birth in the dens and nurse their cubs until they are large enough to venture outside in the spring as snow melts and new food become available.ĭepending on the length of the winter season, grizzly bears can stay in their dens for up to seven months. When inside the den, grizzly bears slow down their heart rate, reduce their temperature and metabolic activity, and live off stored fat reserves. ![]() In late fall or winter, the bears find a hillside and dig a hole to serve as their winter den. Throughout the summer and autumn, grizzly bears build up fat reserves by consuming as much food as they can find. Grizzly bears hibernate in warm dens during the winter to minimize energy expenditure at a time when natural foods are not available and to permit their tiny young to be born in a warm and secure environment. Winter can be very tough for many species of wildlife, because the season brings harsh weather and little food. In many habitats they prefer riparian areas along rivers and streams. Grizzly bears can be found in woodlands, forests, alpine meadows, and prairies. Thanks to conservation efforts since about 1975, grizzly bears are recovering well in Yellowstone and elsewhere in the Northern Rockies and are even beginning to recolonize prairie habitats along the Rocky Mountain Front in Montana. The southern populations in Canada’s British Columbia and Alberta are greatly reduced. A large population of grizzly bears lives inland in Alaska and northern Canada. Populations persisted in the Northern Rocky Mountains including Yellowstone and Glacier National Parks and in northwestern Montana and extreme northern Idaho next to Canada. Control actions and habitat loss extirpated them from 98 percent of their original habitat in the U.S., including the Great Plains and all habitats south of Yellowstone National Park and Grand Teton National Park in Wyoming, including California, Idaho, and Washington. ![]() Grizzly bears once roamed throughout the entire western United States south into Mexico, including the Great Plains and along rivers in desert habitats. A large female can weigh 110 to 160 kilograms (about 250 to 350 pounds) in the lower-48 States. Grizzly bears weigh upward of 700 pounds (315 kilograms). The males are heavier than the females and can weigh 200 to 300 kilograms (about 400 to 600 pounds). They have very long claws on their front feet that also give them extra ability to dig after food and to dig their dens. The hump is where a mass of muscles attach to the bear’s backbone and give the bear additional strength for digging. They have a dished face, short, rounded ears, and a large shoulder hump. ![]() Grizzly bears are large and range in color from very light tan (almost white) to dark brown. Brown bears also occur in Russia, Europe, Scandinavia, and Asia. In North America there are two subspecies of brown bear (Ursus arctos ) : the Kodiak bear, which occurs only on the islands of the Kodiak Archipelago, and the grizzly bear, which occurs everywhere else. However, most of these bears are now considered the same subspecies. Many people in North America use the common name “grizzly bear” to refer to the smaller and lighter-colored bear that occurs in interior areas and the term “brown bear” to refer to the larger and typically darker-colored bear in coastal areas. The grizzly bear is a kind of brown bear. ![]()
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