Polar Bear
Ursus maritimus
Polar bears are among the largest predators in the world. They range in color from pure white after a molt to a yellowish shade resulting from solar oxidation or staining by oil from seal blubber. Their skin, nose and lips are black in color.
Polar bears’ long neck and narrow skull aid in streamlining the animal in water, and their large, flat and oar-like front feet make them strong swimmers. Their fur is thicker than any other bears’ even covering their feet, for warmth and traction on ice. Polar bears also have a thick layer of blubber which provides buoyancy and insulation.
Height 8 to 10 feet
Weight Adult males 550-1700 lbs; females 200 - 700
lbs
Lifespan 20 - 25 years
Diet
Staples Almost exclusively feed on ringed seals and to a lesser extent
bearded seals
Also eat walrus, beluga whale and bowhead whale carcasses,
birds, vegetation and kelp
Population
The World Conservation Union (IUCN) estimates that there are between 20,000-25,000 polar bears in the world.
Range
Polar bears are distributed throughout the arctic region in 19 subpopulations. Alaska, Canada, Russia, Greenland and Norway have polar bear populations.
Behavior
Highly dependant on older stable pack ice in the arctic region, polar bears spend much of their time on the ice hunting, mating and denning. They are generally solitary as adults, except during breeding and cub rearing.
Unlike brown bears, non breeding females and males do not hibernate or den in the winter. Pregnant polar bears need to eat a lot in the summer and fall in order to build up sufficient fat reserves for surviving the denning period, during which time they give birth to one-pound cubs and then nurse them to about 20-30 pounds before emerging from the den in March or April.
Reproduction
Mating Season Late March through May
Gestation About 8
months with delayed implantation
Litter size 1-4 cubs; 2 cubs most
common
Female bears locate denning sites in October on thick stable
pack ice or on land. The young are born from November through January while the
mothers are hibernating. Cubs will remain with their mothers for at least 2 ½
years. Female polar bears can produce five litters in their lifetime, which is
one of the lowest reproductive rates of any mammal.
Threats
Climate change, which is causing the loss of older stable sea ice and the thinning, disappearance and moving offshore of older sea ice, is reducing essential polar bear habitats and is the great threat to their survival. Loss of sea ice leads to higher energy requirements to locate prey and a shortage of food. This causes higher mortality among cubs and reduction in size among first year cubs and adult males. For example, in Alaska 42% of cubs now reach 12 months of age, down from 65% 15 years ago. Another threat is human-caused mortality. Some bears are attracted by unsecured garbage and animal carcasses. This can eventually lead to conflicts between people and bears and lethal removal of the bear. Illegal killing (poaching) of bears also remains another factor causing their decline.
Legal Status/Protection
The polar bear was listed as threatened under the federal Endangered Species Act* on May 14, 2008. This move officially recognizes that polar bears are threatened with extinction from global warming, which is melting the Arctic sea ice where polar bears hunt for ringed and bearded seals, their primary food source.
In May 2006, the International Union for the Conservation of Nature added the polar bear to its "Red List" of the world’s most imperiled animals, predicting a 30% reduction in the polar bear population in the next 45 years.
*The Endangered Species Act requires the US federal government to identify species threatened with extinction, identify habitat they need to survive, and help protect both. In doing so, the Act works to ensure the basic health of our natural ecosystems and protect the legacy of conservation we leave to our children and grandchildren.
How You Can Help
- Help polar bears and other wildlife by adopting a polar bear today at our Wildlife Adoption Center.
- Take Action for Wildlife at our Wildlife Action Center.
For additional information
Visit Defenders' Imperiled Species: Polar Bear pages for more information about what Defenders is doing to help.
Alaska Conservation Solutions
National Wildlife Federation
Pacific
Environment
Polar Bears International
Sierra Club Alaska
Watch SeeMoreHD.com's high definition video footage of polar bears.
