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

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 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.