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The Grizzly or Brown bear (Ursus arctos) is one of the largest and most well-known bears in North America and throughout much of Eurasia. These bears can live up to 30 years in the wild and reach a length of nearly 10 feet and weigh up to 1700 lbs. This species is the most widely distributed of all bears. Brown bears are easily distinguished from other bears by their large size; broad, flat skull; immense forward shoulder hump; and long, curved claws. Like most mammals, brown bears are nocturnal. They are omnivorous and derive most of their diet from plant matter, including berries, roots, young shoots, and nuts. Fish, insects, and mammals are also important diet items. Both males and females have been characterized as polygamous, with the male sequestering the female during the breeding season from late May to early July. During winter sleep, the fetus attaches to the uterine wall and develops. cubs (usually two) are born 8 weeks after implantation. cubs weigh about 1 pound at birth. Feeding on milk during winter, cubs immerge from the den weighing 15 to 20 pounds. Population estimates put the number of brown bears in North America at about 32,000 with 95% of these bears living in Alaska. Bear numbers appear to be on the increase in the Rocky Mountain states, where human populations are relatively dense and conflicts can occur. Statistically, bear-human encounters are rarely aggressive. This photograph was taken in Jasper National Park by Biology Instructor Roy Rea of the University of Northern BC with a canon 5D camera and 300 mm f/2.8 lens.
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Title Annotation:grizzly bear
Publication:The American Biology Teacher
Article Type:Brief article
Geographic Code:1USA
Date:Mar 1, 2012
Words:268
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