USFWS photo by Scott Schliebe 

Female polar bears prepare large dens on the mainland or on sea ice where they will 

give birth and spend winter. Usually two cubs are born in December or January. 

While the cubs are born blind, hairless, and no bigger than squirrels, they grow very 

rapidly. Polar bear cubs remain with their mother for 2-1/4 years. 

U.S. Fish & Wildlife Service


The Polar Bear


Ursus maritimus 

The polar bear, or “Nanuuq,” as the 

Eskimos call it, lives only in the Northern

Hemisphere, on the arctic ice cap, and 

spends most of its time in coastal areas. 

Polar bears are widely dispersed in 

Canada, extending from the northern 

arctic islands south to the Hudson Bay 

area. They are also found in Greenland, 

on islands off the coast of Norway, on the 

northern coast of the former Soviet 

Union, and on the northern and 

northwestern coasts of Alaska in the 

United States. 

Some polar bears may make extensive 

north-south migrations as the pack ice 

recedes northward in the spring and 

advances southward in the fall. They also 

may travel long distances during the 

breeding season to find mates, or in 

search of food. 

Appearance 

The polar bear is the largest member of 

the bear family, with the exception of 

Alaska’s Kodiak brown bears, which equal 

polar bears in size. Males stand from 8 to 

11 feet tall and generally weigh from 500 

to 1,000 pounds, but may weigh as much 

as 1,400 pounds. Females usually stand 8 

feet tall and weigh 400 to 700 pounds, but 

may reach 700 pounds. Part of the reason 

the polar bear weighs so much is that it 

stores about a 4-inch layer of fat to keep 

it warm. 

The polar bear has a longer, narrower 

head and nose, and smaller ears, than 

other bears. 

Although the polar bear’s coat appears 

white, each individual hair is actually a 

clear, hollow tube. Some of the sun’s rays 

bounce off the fur, making the polar 

bear’s coat appear white. During the 

summer months, adult bears molt, or 

gradually shed their coats and grow new 

ones, which look pure white. By the 

following spring, the sunshine has caused 

their coats to turn a yellowish shade. 

Polar bears also sometimes may have a 

yellowish shade to their coats caused by 

staining from seal oils. 

The polar bear’s coat helps it blend in 

with its snow-covered environment, which

is a useful hunting adaptation. The polar 

bear’s front legs appear slightly bowllegged and pigeon-toed, and fur covers 

the bottoms of its paws. These 

adaptations help the polar bear keep 

them from slipping on ice. 

Feeding Habits

 Because the polar bear rarely eats 

vegetation, it is considered a carnivore, or 

meat-eater. The ringed seal is the polar 

bear’s primary prey. A polar bear may 

stalk a seal by waiting quietly for it to 

emerge from its blow hole or “atluk,” an 

opening seals make in the ice allowing 

them to breathe or climb out of the water 

to rest. The polar bear will often have to 

wait for hours for a seal to emerge. 

Because the polar bear’s coat is 

camouflaged against the whiteness of the 

ice and snow, the seal may not see the 

bear. Polar bears typically eat only the 

seal’s skin and blubber, or fat, and the 

remaining meat is an important food 

source for other animals of the Arctic. For 

example, Arctic foxes feed almost 

entirely on the remains of polar bear kills 

during the winter. 

Polar bears also prey on walrus, but, 

because of the walrus’s ferocity and size, 

bears are usually only successful preying 

on the young. The carcasses of whales, 

seals, and walrus are also important food 
sources for polar bears. In fact, because of

their acute sense of smell, polar bears can

sense carcasses from many miles away. 

Polar bears can cover significant 

distances on land, but are most agile in 

the sea. They are excellent swimmers, 

and can reach speeds of up to 6 mph in the

water. They are good divers, too. When 

being pursued by hunters in open water, 

polar bears have been known to escape by

plunging 10 to 15 feet below the surface 

and resurfacing a good distance away. 

They also have been seen swimming 100 

miles or more from ice or land. 

Reproduction 

Polar bears reach breeding maturity at 3 

to 5 years of age. Males may travel great 

distances in search of female mates. 

While breeding usually takes place in 

April, the embryos may not implant 

(develop) until the following year, 

depending on whether the mother has had

a stable enough supply of food to sustain 

herself while allowing her to feed the 

developing cubs through the winter. 

In October and November, male polar 

bears begin to head out on the pack ice 

where they spend the winter. Pregnant 

females, however, seek sites on the 

mainland or on sea ice to dig large dens in

snow where they will give birth and 

spend the winter. The temperature inside 

the polar bear’s den can be as much as 40 

degrees warmer than outside. Usually 

two cubs are born in December or 

January. When the cubs first arrive, they 

are blind, hairless, and no bigger than 

squirrels. However, the cubs grow rapidly

from the rich milk provided by their 

mother. 

As soon as spring comes, the mother bear 

leads her cubs to the coast along the open 

sea, where seals and walrus are abundant.

The mother will fiercely protect her cubs 

from any perceived danger. The cubs 

remain with their mother for 2-1/4 years. 

Because of this, most adult female polar 

bears breed only every third year. 

Protection 

Polar bears have traditionally played an 

important role in the culture and 

livelihood of Eskimos and other Native 

people of the North. They depend on the 

animals for food and clothing. 

In the United States, polar bears are a 

federally protected species under the 

Marine Mammal Protection Act of 1972. 

This protection prohibits hunting of polar

bears by non-Natives and establishes 

special conditions for the importation of 

USFWS photo by Dave Olsen 

polar bears or their parts and products 

into the United States. Eskimos and 

other Alaska Natives are allowed to 

harvest some polar bears for subsistence 

and handicraft purposes. The U.S. Fish 

and Wildlife Service is the federal agency 

responsible for managing polar bears 

under the Marine Mammal Protection Act. 

An international conservation agreement 

for polar bears signed in 1976 by the 

United States, the former Soviet Union, 

Norway, Canada, and Denmark 

(Greenland) also provides for cooperative 

management of polar bears. 

The Fish and Wildlife Service and the 

United States Geological Survey’s Alaska 

Science Center work together to monitor 

polar bears in Alaska, where they number 

approximately 4,700, and study their 

behavior. Cooperative efforts with 

Canada involve monitoring polar bears in 

the Beaufort Sea, and the agencies work 

with the Russian government to monitor 

the animals in the Chukchi Sea. 

Another treaty, the “Agreement between 

the Government of the United States of 

America and the Government of the 

Russian Federation on the Conservation 

and Management of the Alaska-Chukotka 

Polar Bear Population,” unifies the 

American and Russian management 

programs that affect this shared 

population of bears. Notably, the treaty 

calls for the active involvement of Native 

people and their organizations in future 

management programs. It will also 

enhance long-term joint efforts such as 

conservation of ecosystems and important 

habitats, harvest allocations based on 

sustainability, collection of biological 

information, and increased consultation 

and cooperation with state, local, and 

private interests. The Fish and Wildlife 

Service also undertakes education and 

outreach efforts to inform the public 

about how polar bears can be protected 

from over-harvest. 

In Alaska, demands for oil, natural gas, 

and other resources have led to some 

conflicts between polar bears and 

humans. A number of protective 

measures have been taken to reduce 

human activities along the coast in polar 

bear denning areas. This is when the 

animals are most sensitive to outside 

disturbances. For example, oil and gas 

pipelines and roads have been routed to 

avoid these areas. The Fish and Wildlife 

Service also provides expertise to 

industries on how to minimize conflicts 

with bears while conducting their 

operations. 

Today it is estimated that there are 20,000 

to 25,000 polar bears worldwide. With 

continued cooperative management, these 

great marine mammals, and the unique 

arctic environment on which they depend, 

can be protected for generations to come. 

U.S. Fish & Wildlife Service 

1 800/344 WILD 

http://www.fws.gov 

December 2006