BROWN BEAR (Ursus arctos)


ALASKAN WILDLIFE NOTEBOOK SERIES


From

Alaska Department of Fish and Game
by:
Sterling Eide and Sterling Miller

Brown bears occur throughout Alaska except on the islands south of Fredrick Sound in southeastern Alaska, the islands west of Unimak in the Aleutian Chain and the islands of the Bering Sea. They also occur in Europe, Asia, Canada and in limited numbers in a few western states. Brown bears are very much a part of the Alaskan scene and are a favorite topic with most hunters, hikers and fishermen.

GENERAL DESCRIPTION: Formerly, taxonomists listed brown and grizzly bears as separate species. All brown and grizzly bears are now classified as the same species, Ursus arctos. In popular usage brown bear refers to members of this species found in coastal areas, while those found inland are commonly called grizzlies. In this paper brown bear is used in the general sense: it refers to all members of Ursus arctos.

The brown bear resembles its close relative the black bear, Ursus americanus. The brown bear, however, is usually larger, has a more prominent shoulder hump and longer, straighter claws. Other characteristics such as the shape and relative massiveness of the head help to differentiate these species. The most positive identification is provided by measurement of the upper rear molar. In the brown bear, the length of the crown of this tooth is more than one and one quarter inches. In black bear, it is less than one and one quarter inches. Color is not very reliable key in differentiating these bears for both species have many color phases. Black bears, for example, occur in many hues of brown. Brown bear colors range from dark brown through blond.

Bear weights vary throughout the year. Bears weigh less in the spring and early summer. They gain weight rapidly during the late summer and fall and are waddling fat just prior to denning. At this time most mature males weigh between 400 and 900 pounds (181.8-409.1 kg) with extremely large individuals weighing as much as 1,400 pounds (636.4 kg). Females weigh one-half to three quarters as much.

An extremely large brown bear has a skull approaching 18 inches long (45.7 cm). Such a bear when standing on its hind feet is about nine feet (2.7 m) tall. Inland bears are usually smaller than coastal bears, perhaps because they lack the rich supply of fish.

Brown bears have been known to live 30 years in captivity where they do not have to forage for food. In the wild a brown bear is an old timer at 20.

LIFE HISTORY: Mating takes place from May through July with the peak of activity in early June. Brown bears generally do not have strong mating ties, but individual bears have been observed remaining with their mates for more than a month. Males may mate with more than one female during breeding season. The hairless young, weighing less than a pound, are born the following January and February in a winter den. Litter size ranges from one to four cubs, but two is most common. Offspring typically separate from their mothers in May or June of their third year of life. Following separation, the mother can breed again and produce a new litter of cubs the following year. In some parts of Alaska research results reveal that offspring may not separate from their mothers until they are three-to-five years old. This appears to be most common in areas where food is scarce or where bear populations are most dense. Also, in environments without much bear food, females may skip one-to-three years before producing new litters.

Bear populations vary depending on the productivity of the environment. In areas of low productivity such as on Alaska's north slope, studies have revealed bear densities as low as one bear per 100 square miles. In areas teeming with bear food such as Admiralty Island in southeastern Alaska, densities as high as one bear per square mile have been found. In central Alaska, both north and south of the Alaska Range, bear densities tend to be intermediate, about one bear per 15-17 square miles. These are average figures which shouldn't be interpreted to mean that each bear has this much territory for its exclusive use. The area occupied by any individual bear overlaps that used by many other individuals.

SAFETY: All brown bears should be treated with respect and can be safely observed only from distances of at least 100 yards. This is especially true for family groups of a female and her offspring as mother bears are very protective towards their young. Bears protecting a food source, such as the buried carcass of a moose or caribou, should also be treated with special caution. In bear country, campers can best avoid conflicts with bears if they minimize food odors and store their food out of a bears reach and away from camp.

FOOD HABITS: The brown bear is omnivorous. Common foods include berries, grass, sedge, horsetail, vow parsnip, fish and roots of many plants. In some parts of Alaska, brown bears have been shown to be capable predators of newborn moose and caribou. They can also kill and consume healthy adults of these species and domestic animals. Bears are fond of all kinds of carrion as well as garbage in human dumps.

Except for females with offspring and breeding animals, bears are typically solitary creatures and avoid the company of other bears. Exceptions to this occur where food sources are particularly concentrated such as streams where bears can catch salmon swimming upstream to spawn. At one such area on the McNeil River, biologists have observed more than 60 bears at one time.

WINTER DORMANCY: In the winter when food is unavailable or scarce, most Alaskan brown bears enter dens and sleep through the winter. In their dens bears enter a state of winter dormancy or hibernation. In this state their body temperatures and metabolic rates are slightly reduced and other physiological changes occur which reduce their need for food to zero. In northern areas with long and hard winters bears may spend six-to-seven months in dens. In areas with relatively warmer winters such as Kodiak Island, it appears that a few bears may not enter dens all winter. Available evidences suggest that pregnant females are the first to enter dens in the fall, and these same females, with their newborn cubs, are the last to exit dens. Adult males, on the other hand, appear to enter dens later and emerge earlier than most other bears.

HUNTING: Bear hunting is popular in Alaska. Bear meat should be thoroughly cooked to prevent contracting trichinosis, a parasitic disease that may be fatal to man. Bear hunting seasons are held in both spring and fall in some areas but only in the fall in other areas. Cubs and females with offspring may not be killed.

A bear should be examined closely, preferably with binoculars, before shooting to determine if the pelt has rubbed spots since skins without rubbed spots are preferred by most hunters. A little extra time spent observing a bear before shooting may also prevent the hunter form taking a sow which has cubs hidden nearby.

RESEARCH AND CONSERVATION: Alaska contains more than 98 percent of the United States population of brown bears and more than 70 percent of the North American population. From this it can be seen that Alaska has a special responsibility for this large carnivore. The Alaska Department of Fish and Game is responsible for managing bears in Alaska and has conducted numerous studies to assure that this important species is correctly managed. Preservation of bear habitat and prevention of over-harvest are both important components of these management efforts. As Alaska continues to develop it is increasingly important for land management agencies and the public to recognize that maintaining sufficient amounts of habitat for brown bears to continue to thrive in Alaska will, in some places, mean forgoing opportunities for some kinds of economic development in some places.