|
Brown Bear
Brown bears (Ursus arctos) occur throughout
Alaska except on the islands south of Frederick Sound in southeastern
Alaska, the islands west of Unimak in the Aleutian Chain, and the
islands of the Bering Sea. They also occur in Canada, Asia, Europe,
and in limited numbers in a few western states. Brown bears are very
much a part of the Alaska scene and are a favorite topic with most
hunters, hikers, photographers, and fishers.
General description: Formerly, taxonomists listed
brown and grizzly bears as separate species. Technically, brown and
grizzly bears are classified as the same species, Ursus arctos.
Brown bears on Kodiak Island are classified as a distinct subspecies
from those on the mainland because they are genetically and physically
isolated. The shape of their skulls also differs slightly.
The term “brown bear” is commonly used to
refer to the members of this species found in coastal areas where
salmon is the primary food source. Brown bears found inland and in
northern habitats are often called “grizzlies.” In this
paper, brown bear is used to refer 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, less prominent ears, and
longer, straighter claws. Both the prominent hump and the long claws
of the brown bear are adaptations that are related to feeding behavior.
The long claws are useful in digging for roots or excavating burrows
of small mammals. The musculature and bone structure of the hump are
adaptations for digging and for attaining bursts of speed necessary
for capture of moose or caribou for food. Color is not a reliable
key in differentiating these bears because both species have many
color phases. Black bears, for example, occur in many hues of brown,
and even shades of blue and white. Brown bear colors range from dark
brown through light blond.
Bear weights vary depending on the time of year. Bears
weigh the least in the spring or early summer. They gain weight rapidly
during late summer and fall and are waddling fat just prior to denning.
At this time most mature males weigh between 500 and 900 pounds (180-410
kg) with extremely large individuals weighing as much as 1,400 pounds
(640 kg). Females weigh half to three-quarters as much. An extremely
large brown bear may have a skull 18 inches long (46 cm) and 12 inches
wide (30 cm). Such a bear, when standing on its hind feet, is about
9 feet (2.7 m) tall. Inland bears are usually smaller than coastal
bears, probably because they do not have a readily available supply
of protein-rich food, such as salmon, in their diet.
Brown bears have been known to live 34 years in the
wild, though this is rare. Usually, old males may reach 22 years.
Old females may live to 26. Brown bears have an especially good sense
of smell and under the right conditions may be able to detect odors
more than a mile distant. Their hearing and eyesight are probably
equivalent to that of humans. When bears stand upright, it is not
to get ready to charge but to test the wind and to see better.
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. Individual bears are rarely seen with
a mate for more than a week. Males may mate with more than one female
during breeding season. The hairless young, weighing less than a pound,
are born the following January or February in a winter den. Litter
size ranges from one to four cubs, but two is most common. Offspring
typically separate from their mothers as 2-year olds in May or June.
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 3 to 5 years old. This appears to be most common in
areas where food is scarce. In some of these areas, 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 300 square miles. In areas teeming with easily available food,
such as Admiralty Island in Southeast 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 15-23 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 may
overlap that used by many other individuals.
Safety: All brown bears should be treated with
respect and can be safely observed only from a distance 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, store their food out of a bear’s reach and away from their
camp, and avoid camping on bear travel routes.
Food habits: Like humans, brown bears consume
a wide variety of foods. Common foods include berries, grasses, sedges,
horsetails, cow parsnips, fish, ground squirrels, and roots of many
kinds of 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 types 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 concentrated
such as streams where bears can catch salmon swimming upstream to
spawn. At McNeil River Falls, the largest concentration of brown bears
occurs annually. Biologists have observed more than 60 bears at one
time, attracted by spawning salmon.
Winter dormancy: In the winter when food is
unavailable or scarce, most Alaska brown bears enter dens and hibernate
through the winter. While in this state, their body temperatures,
heart rate, and other metabolic rates are reduced. Their need for
food and water is eliminated. In northern areas with long hard winters,
bears may spend from 5 to 7 ½ months in dens. In areas with relatively
warmer winters, such as Kodiak Island, a few bears may stay active
all winter. Pregnant females are usually the first to enter dens in
the fall. These 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 and,
with proper management, can occur without causing populations to decline.
Bear hunting seasons are held in both spring and fall in some areas
but only in fall in other areas. Cubs and females with offspring may
not be killed. Bear meat should be thoroughly cooked to prevent contracting
trichinosis,
a parasitic disease that may be fatal to man.
Hunters should examine bears closely with binoculars
before shooting to determine if the pelt has spots where the hair
has been rubbed away. Such rubbed spots result in a poorer quality
hide. A little extra time spent observing a bear before shooting may
also prevent the hunter from taking a female that has cubs hidden
nearby. An excellent guide to judging trophy brown bears and distinguishing
between sexes of bears is the Take a Closer Look video which
is available for viewing at most Alaska Department of Fish and Game
offices.
Research and conservation: Because Alaska contains
over 98 percent of the United States population of brown bears, and
more than 70 percent of the North American population, it has a special
responsibility for this large carnivore. The Alaska Department of
Fish and Game is responsible for managing bears in Alaska and for
ensuring that management is based on scientific knowledge of the biology
of bear populations. Important components of this management effort
include maintaining healthy populations of bears throughout Alaska,
conservation of bear habitat, prevention of overharvest, and conducting
the studies necessary to understand population requirements. As Alaska
continues to develop, it is increasingly important for the public
to recognize that conserving sufficient amounts of habitat is necessary
for brown bears to continue to thrive in Alaska.
Text: Sterling Eide and Sterling Miller
Illustration: R.T. Wallen
Revised by Harry Reynolds and reprinted 1994, website revisions 2003
View a range
map for brown bears.
Wildlife Notebook Series Home
|
