American black bears appear in a variety of colors despite  their name. In the eastern part, most of these bears have shiny black fur, but in the west they grow brown, red, or even yellow coats. To the north, the black bear is actually gray or white in color. Even in the same litter , both brown and black furred bears may be born. Black bears are the smallest of all American bears, ranging in length from five to six feet, weighing from three hundred to five hundred pounds. Their eyes and ears are small and their eyesight and hearing are not as good as their sense of smell. Like all bears, the black bear is timid and rarely dangerous, but if attacked, most can climb trees or cover ground at great speed. When angry or frightened, they are formidable  _ . Black bears feed on leaves, roots, fruit, insects, fish, and even larger animals. One of the most interesting characteristics of bears, including the black bear, is their winter sleep. Unlike squirrels and many other woodland animals, bears do not actually sleep through the winter months. Although the bear does not eat during the winter months, sustaining  itself from body fat, its temperature remains almost normal, and it breathes regularly four or five times per minute. Most black bears live alone, except during the mating  season. They prefer to live in caves. Baby black bears are born in January or February after a gestation  period of six to nine months, and they stay with their mother until they are fully grown or about one and a half years old. Black bears can live as long as thirty years in the wild, and even longer in some nature reserves. American black bears may have   _   colours according to the passage.
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