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Bears have long
fascinated humans. Ancient cave art and more recent paintings and sculpture illustrate
the fear as well as admiration with which people regard the awesome
power and acute intelligence of bears. In fairy tales, bears are the
symbolic image of brave deeds. In folk literature, the bear's habit
of disappearing in winter months and emerging in spring evokes a
theme of spiritual renewal, the replenishment of food, and the
return of prosperity. In modern times, as the recreational use of
parks and wilderness areas has grown dramatically, humans have
experienced increased contact with bears. Bear attacks on humans are
rare, however. American black bears killed fewer than 40 people
during the 20th century. Grizzly bears, a type of brown bear, are
more dangerous, but attacks on humans are still rare. In United
States national parks that are home to grizzlies, injury rates from
grizzly bears are about one person per 2 million visitors. Bears
prefer to avoid humans, but when attacks do occur, they are usually
the result of humans surprising these nervous, shy, and easily
frightened animals. Bears are bulky
animals with wide shoulders, a short back, short and thick legs,
broad paws, and a short tail. They have an elongated head, rounded
ears that stand straight up, small eyes, and a long snout. Bears
hunt for food using an acute sense of hearing and an extremely keen
sense of smell--some can detect odors from more than a mile away.
Bear eyesight is probably similar in acuity (sharpness) to human
vision. Black bears, and likely other bears, have color vision,
which helps them identify ripe fruits and nuts.
Bears
have 32 to 42 teeth, depending on the species, and these teeth
reflect a varied diet of both plants and animals. Although all bears
are members of the order Carnivore and are meat eaters, all but
polar bears have become omnivorous--that is, they eat many types of
foods, including lichens, roots, nuts, fruits, berries, seaweed,
grasses, honey, grubs, caterpillars, and ants. Bear teeth are not as
sharp or specialized for shearing meat as are those of some other
carnivores, such as cats. For instance, canine teeth in most
carnivores are generally large and pointed and are used for killing
prey. In bears, however, these teeth are relatively small, and bears
typically use them more to defend themselves or as tools. The molar
teeth of bears are broad and flat, adapted to shredding and grinding
plant food into small, easily digested pieces. Bears have four limbs that end in paws. Each
paw has five long, sharp claws that are unretractile--unlike cats,
bears are not able to retract their claws. Depending on the species,
these claws may be used to climb trees, rip open termite nests and
beehives, dig up roots, or catch prey. Bears walk differently than
most carnivores, which tend to walk on their toes in a way that is
adapted for speed. Like humans, bears have a plantigrade stance,
walking with their weight on the soles of their hind feet, with the
heel touching the ground, while the toes of the forefeet are used
more for balance. This distribution of weight toward the hind feet
gives bears a lumbering gait. Although bears are slower than most
other carnivores, such as lions and wolves, a running bear can still
reach speeds of 50 km/h (30 mph). Bears are far stronger than other
carnivores, and their limbs are more flexible and agile. Bear fur is long and shaggy. Fur color varies
among species, ranging from all white, blonde, or cream to black and
white to all black or all brown. Fur color may also vary within a
species. American black bears, for instance, may be black, brown,
reddish-brown, or bluish-black. Several species, such as the sun
bear and spectacled bear, have lighter-colored chest and facial
markings.
Males are larger than
females in all bear species, but the difference between the sexes
varies and is greatest in the largest species. Huge male polar bears
may weigh twice as much as female polar bears, while smaller male
and female sun bears are similar in weight. The life span of bears is not well known. The
range seems to be about 25 to 40 years. Bears in the wild tend to
die at a younger age than do their counterparts in zoos.
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