A symbol of America’s wildlands, the

grizzly or brown bear is one of the

largest North American land mammals.

The grizzly bear’s historic range

covered much of North America from

the mid-plains westward to California

and from central Mexico north

throughout Alaska and Canada. Today,

the grizzly bear is found in only about

2 percent of its original range in the

lower 48 states.

Grizzly bears need a very large home

range (50 to 300 square miles for

females; 200 to 500 square miles for

males), encompassing diverse forests

interspersed with moist meadows and

grasslands in or near mountains. In the

spring, bears usually range at lower

elevations and go to higher altitudes for

winter hibernation.

Larger than the black bear, male

grizzly bears stand about 7 feet tall

and weigh from 300 to 600 pounds

(and occasionally more than 800).

Females are smaller, usually weighing

between 200 and 400 pounds. Although

a standing grizzly is commonly

perceived to be a threatening pose,

bears stand when they are simply

curious or surveying their

surroundings. Otherwise they

generally remain on all fours.

The grizzly can be distinguished from

the black bear by its concave face,

high-humped shoulders, and long,

curved claws. Its thick fur, which varies

from light brown to nearly black, may

appear frosted, hence the name

“grizzly,” or the less common

“silvertip.” The grizzly has shorter,

rounder ears than the black bear.

Except for mating and caring for the

young, grizzly bears lead primarily

solitary lives, spending most of their

time foraging, (looking for food). The

grizzly is North America’s largest

omnivore, meaning it eats both plants

and other animals. About 80 to 90

percent of the grizzly’s food is green

vegetation and insects. Grizzlies eat

wild fruits and berries, nuts, bulbs or

roots of certain plants, and sometimes

tear rotten logs apart or turn over

heavy stones in search of insects or

their larvae.

Most of the meat in the grizzly’s 

diet comes from carcasses (carrion) 

of big game animals, although it will

sometimes prey on elk or moose calves

or smaller mammals. For grizzlies

along the west coast of Canada and in

Alaska, salmon is an important food

source.

The grizzly bear must eat enough to

store huge amounts of fat needed to

sustain it through its long winter sleep.

The grizzly’s ability to eat large

quantities of rich food and store fat

without suffering from heart disease or

cholesterol problems is of great interest

to medical scientists. If scientists can

determine how grizzlies accomplish

this, that information may be useful in

preventing human heart disease.

At the top of the food chain, adult

grizzly bears have little to fear from

other wild animals. Grizzly cubs may

fall prey to mountain lions, wolves, and

other bears if they stray too far from

their mother.

Early in the fall, grizzly bears begin

looking for a proper place to dig their

dens and may travel many miles before

finding a suitable area. Generally, they

seek a high, remote mountain slope

where deep snow will lie until spring to

serve as insulation. Grizzlies sometimes

dig beneath the roots of large trees to

create their dens. Obstructing roots are

chewed up and loose rocks and earth

are thrust through the narrow entrance

by the powerful strokes of the grizzly’s

forepaws.

The grizzly bear will generally enter its

den in October or November. During

the next 5 to 6 months, the grizzly will

get no water or nourishment of any

kind but will use up its accumulated fat.

Male grizzly bears usually emerge from

the den in March or April while females

emerge in mid-April and May. When a

grizzly comes out of its den, the first

food is sometimes carrion from animals

that did not survive the winter. A

grizzly will usually travel to lower

elevations to reach vegetated areas.

Mating season is from June through

July. Grizzly bear embryos do not begin

to develop until the mother begins her

winter hibernation, although mating

Grizzly Bear Facts

Ursus arctos horribilis

U.S. Fish & Wildlife Service

The grizzly has the second slowest

reproductive rate of all North

American mammals (the musk ox has

the slowest), making it harder for it to

rebound from threats to its survival.
may have taken place up to 6 months

before. As with other bears, if the

mother has not accumulated enough fat

to sustain herself as well as developing

cubs, the embryos may not implant

(develop).

In January, usually one to three cubs,

each weighing only a pound or less, are

born. The cubs gain weight quickly and

often have reached 20 pounds by the

time they come out of the den. As many

as half of all cubs may not reach

breeding age — a leading reason for

the grizzly’s low numbers.

Cubs remain dependent upon their

mother’s milk for almost a year, stay

with their mother for 2 to 3 years, and

reach breeding maturity at about 41⁄2 to

51⁄2 years. In some cases they may not

breed until 81⁄2 years of age. When they

do reach breeding age, females only

breed every 3 or more years. Males

compete with each other for breeding

opportunities and seek females each

year. Grizzlies usually live to be 15 to

20 years of age. A few survive up to

30 years.

Between 1800 and 1975, grizzly bear

populations in the lower 48 states

decreased from estimates of more than

50,000 to fewer than 1,000. The grizzly

was eliminated from much of the West

by the late 1800s. As mountainous areas

were settled, development contributed

to an increase in human-caused

mortality. Livestock depredation

control, habitat deterioration,

commercial trapping, unregulated

hunting, and the perception that

grizzlies threatened human life were

leading causes of the animal’s decline.

In 1975, the U.S. Fish & Wildlife Service

listed the grizzly bear as a threatened

species under the Endangered Species

Act, meaning it is considered likely to

become endangered (“endangered”

means a species is considered in danger

of extinction within all or a significant

portion of its range).

Many of the current threats to the

survival of grizzly bears are associated

with degradation of habitat due to rural

or recreational development, road

building, and energy and mineral

exploration. Habitat destruction in

valley bottoms and riparian areas is

particularly harmful to grizzlies

because they use these “corridors” to

travel from one area to another when

they are searching for food. Some

private landowners and companies are

trying to help grizzlies by voluntarily

protecting grizzly habitat.

Some grizzly bears are accidentally

killed by hunters who mistake them for

black bears, which are legal game.

Grizzlies also become habituated to

humans because of what biologists call

“attractants,” which include garbage,

pet foods, livestock carcasses, human

foods, and items associated with

improper camping practices. This can

eventually lead to conflicts between

people and bears both in populated

areas of the grizzly’s range and in back

country recreation sites.

Today, in the lower 48 states, grizzlies

can be found in Wyoming, Montana,

Idaho, and Washington. There are at

least 300–400 grizzlies living in the

northwestern Montana Rockies, about

400–600 in and around Yellowstone

National Park, about 45–50 in the

Selkirk Mountains in northern Idaho

and northeast Washington, another 35–

40 in the Cabinet-Yaak ecosystem in

northern Idaho and western Montana,

and 5–30 in the North Cascades. In

Alaska, where they are called brown

bears, they are estimated to number

more than 30,000. There are about

22,000 grizzly bears in Canada.

One goal of the Fish and Wildlife

Service’s plan to restore the grizzly

bear in the lower 48 states is to recover

grizzly populations in all of the

ecosystems known to have suitable

habitat. The six ecosystems in the

conterminous U.S. that have been

identified by biologists as suitable for

grizzly bears are Yellowstone

(northwestern Wyoming, southwestern

Montana, and eastern Idaho), Northern

Continental Divide and Cabinet-Yaak

(northwestern Montana), Bitterroot

(central Idaho and western Montana),

Selkirks (Idaho and eastern

Washington), and the North Cascades

(Washington). There is currently no

scientific evidence of grizzlies in the

Bitterroot ecosystem (although they

previously inhabited the area), so

reintroduction of bears from other areas

is necessary to recover that population.

The grizzly bear recovery effort has

been met with some successes thus far.

Grizzlies in the Yellowstone ecosystem

have increased significantly. There has

also been some success in the Northern

Continental Divide ecosystem but more

work needs to be done in all of the

areas to reach recovery.

These successes have been largely due

to efforts of the Interagency Grizzly

Bear Committee. Established in 1983,

the committee includes representatives

from the U.S. Fish & Wildlife Service;

U.S. Forest Service; National Park

Service; Bureau of Indian Affairs;

Bureau of Land Management; state

agencies in Idaho, Montana,

Washington, and Wyoming; and

Canadian wildlife agencies in Alberta

and British Columbia.

U.S. Department of the Interior

U.S. Fish & Wildlife Service

http://www.fws.gov

April 2000

The grizzly can be distinguished from

the black bear by its concave face,

high-humped shoulders, and long,

curved claws.

The grizzly’s den is often dug beneath

the roots of a large tree on a mountain

slope where snow will lie through the

winter months to serve as insulation.