The Body and Life of a Bear

Bear is a large, powerful animal with thick, shaggy fur. Bears prey on other animals and are classified by zoologists as carnivores — that is, animals that eat chiefly meat. But most bear species also eat other foods, including fruit, nuts, leaves, insects, and fish.

The Alaskan brown bear is the largest carnivore that lives on land. It grows about 9 feet (2.7 meters) long and may weigh up to 1 ,700 pounds (770 kilograms). The sun bear, also called the Malayan bear, is the smallest bear. It is 3 to 4 feet (91 to 1 20 centimeters) long and weighs only 60 to 100 pounds (27 to 45 kilograms).

A mother brown bear and her cubs fish for salmon

Most wild bears live north of the equator. They are found in Asia, Europe, and North America, and in the Arctic near the North Pole. Only one species, the spectacled bear, lives in South America. No wild bears live in Africa, Antarctica, or Australia.

The body of a bear. Most bears have heavy bodies with long, thick fur, loose skin, and large, hairy heads. Bears have small eyes and cannot see well. Their small, rounded ears stand straight up, but they hear only fairly well. They have an excellent sense of smell. Bears have short, strong legs and large feet. Each foot has five toes, and each toe ends in a long, heavy claw. The claws can always be seen because, unlike those of a cat, they have no covering. A bear uses its claws to dig up roots, ants, termites, and other food, or to tear its prey.

A bear's walk differs from that of most other animals. Most animals walk and run on their toes. A bear, like a human being, puts the entire sole of its foot on the ground with each step and the heel of the foot strikes the ground first. The hind feet of a large bear may be 12 to 16 inches (30 to 41 centimeters) long. The large feet, the short legs, and heel-first way of stepping make bears look slow and clumsy. But bears are agile and can move fast. Polar bears can run at speeds of up to 35 miles (56 kilometers) an hour.

The life of a bear. Bears usually live alone and never gather in groups. During the mating season in the summer, a male and a female bear may live together for about a month. Then the male wanders away and the female prepares a place for her cubs to be born.

Winter sleep. Some bears spend much of the winter in a state similar to sleeping. Many scientists consider the bear's winter sleep to be an example of hibernation. Many other scientists, however, do not consider bears to be true hibernators. They point out that a bear's body temperature, unlike that of other hibernating mammals, does not drop greatly during winter sleep. In addition, a bear awakens easily and may become fairly active on mild winter days. These scientists use such terms as "winter lethargy" or "incomplete hibernation" to describe the bear's sleep period. See Hibernation.

A bear prepares for its winter sleep by eating large amounts of food during late summer and storing fat within its body for energy. When food becomes scarce, the bear goes to its den. The den may be a cave or a brush pile, or a burrow that the bear has dug under the roots of a large tree. Some kinds of bears may build shelters of twigs or dig shallow holes in hillsides. Female polar bears find ice caves or dig dens in the snow.

Brown bears and black bears, both of which live in regions that have harsh winters, almost always have a period of winter sleep. Species found in areas with milder winters may enter dens for only brief periods. Tropical species, such as sun bears and sloth bears, do not have a winter sleep period. Although polar bears live in the Arctic, they normally remain active during the winter. These bears spend the winter wandering the polar ice near open water and preying on seals and other marine mammals that come ashore.

Cubs. Most bear cubs are born during the mother's winter sleep period. A female bear usually has two cubs at a time, but the number may vary from one to four. The cubs weigh only ½ to 1 pound (0.23 to 0.5 kilogram) at birth. Their eyes are closed, and they have no fur. The eyes open about a month after birth, and by that time the body is covered with thick, soft fur. The cubs stay in the den with their mother for about two months. In spring, they come out, frisky and playful. They grow rapidly and may weigh 40 pounds (18 kilograms) by autumn. Cubs stay with the mother for one or two years. She teaches them to hunt for food.

Food. Bears are meat-eating animals, but they also eat many other foods. They hunt mice, ground squirrels, and other small animals in fields and forests. They may wade into streams and catch fish with their front paws or strong jaws. Favorite foods of bears include ants, birds' eggs, and grubs (see Grub). Bears sometimes prey on livestock, especially lambs and young pigs. Their diet also may include acorns, berries, fruits, nuts, and the leaves and roots of plants. Bears are fond of honey and will rip apart beehives or the nests of wild bees to get it. Their long, thick fur helps protect them from bee stings.

Habits. Bears often wander far in search of food. A grizzly bear may claim an area of 10 to 12 square miles (26 to 31 square kilometers) as its private hunting ground. Polar bears swim well and are often found living on islands of ice drifting more than 200 miles (320 kilometers) from land.

Bears are usually peaceful animals. They try to avoid a fight and run from danger. They have few enemies except other bears and humans. Bears show no fear of people and often wander into camping areas looking for food. However, all bears are short-tempered and get angry quickly. They are fierce fighters and will attack anything that seems to threaten them or their cubs, food, or homes. An angry bear moves quickly in spite of its great size. One blow from its powerful front paws can kill even large animals, such as cattle and deer. The long, thick claws are also dangerous weapons. Few bears lose a fight with another kind of animal.

Wild bears live from 15 to more than 30 years. In zoos, a brown bear has lived as long as 47 years, and a polar bear for 34 years.