Bear

I

Introduction

Bear, any of a group of mammals distinguished by a large, stocky body; powerful limbs; dense fur; and a short, stumpy tail. Bears live in North America, South America, Europe, and Asia, where they occupy a wide range of habitats, including mountain, forest, and Arctic wilderness. Over the last century bear populations have steadily declined as humans have overhunted bears and encroached on their habitat. Climate change has also threatened polar bears in the Arctic.

Zoologists (scientists who study animals) classify eight species of bears: giant panda, spectacled bear, sun bear, sloth bear, Asiatic black bear, American black bear, brown bear, and polar bear. All of these species, with the exception of some populations of spectacled bears and sun bears, live north of the equator. Bears are not currently found in Africa, Australia, or Antarctica. All bears share a similar anatomy, but individual species vary in size, diet, and type of habitat. For example, polar bears live in frozen Arctic wilderness, where they feed primarily on seals, while sun bears live in Asian rain forests and dine on insects, fruits, nuts, and small animals. Reaching weights of 800 kg (1,760 lb), polar bears may grow 12 times larger than their smaller cousins the sun bears, which rarely exceed 66 kg (146 lb) in weight.

Bears have long fascinated humans. Paleolithic art as well as more recent paintings and sculpture illustrate the fear and 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.

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II

Physical Description

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. Bears may have the best sense of smell of any mammal—some can detect odors up to a mile or more 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 Carnivora 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 hindfeet, with the heel touching the ground, while the toes of the forefeet are used more for balance. This distribution of weight toward the hindfeet 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.

III

Types of Bears

The bear family includes eight species, each showing remarkable variation in physical features and habits. Some scientists believe that bears and animals in the raccoon family share a common ancestor and are more closely related to each other than to other carnivores. Other scientists believe that bears are more closely related to walruses and sea lions. In the past, zoologists placed the giant panda in the raccoon family, but recent analysis of the giant panda’s genetic makeup and fossil evidence have convincingly established the giant panda as a member of the bear family.

A

Giant Panda

Possibly the world’s best-known wild animal, the giant panda has a round body, a bullet-like head with small ears, and a short, stumpy tail. Its shaggy coat is white with a black patch around each eye and a ring of black around the shoulders, front legs, and chest. The giant panda can reach a length of 1.5 m (5 ft) and weigh 100 kg (220 lb).

The giant panda has the smallest range and smallest population of all the bears. Only about 1,600 individuals live in bamboo forests in the mountains of south-central China. Bamboo makes up about 99 percent of the giant panda’s diet, and the bear spends 12 to 14 hours each day eating up to 18 kg (40 lb) of bamboo leaves and stems or 39 kg (85 lb) of shoots. The giant panda brings food to its mouth with its front paws, using a long wrist bone that works like a thumb to grasp bamboo stems. Despite their cute, cuddly appearance, giant pandas can be provoked to aggressive defensive behavior.

With such a small population, a narrow habitat range, and a highly specialized diet, the giant panda is widely considered in great danger of extinction. It has been classified as an endangered species by both the United States Fish and Wildlife Service and the World Conservation Union (IUCN), a nongovernmental organization that compiles global information on threatened and endangered species. These classifications offer the animals protection and provide opportunities for conservation management, including strictly enforced protection from hunting in their habitats. The Chinese government, as well as many private organizations and zoos around the world, support conservation activities that encourage local people to protect the giant panda and its habitat. A number of programs sponsored by zoos or other breeding centers have attempted to breed giant pandas in captivity, although most of these programs have proved unsuccessful. Among the difficulties faced by captive breeders has been the problem of encouraging a female giant panda to mate with a selected male during the two to three days of the year when she is most fertile, a period known as estrus.

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