Polar Bear (Ursus maritimus) Fact Sheet: Summary

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia

Order: Carnivora

Family: Ursidae

Genus: Ursus — bears

Species: Ursus maritimus — polar bear, white bear, sea bear

Head/Body Length

Female: 200 cm (6 ft)
Male: 250 cm (8.2 ft)

Tail Length

76–127 mm (3–5 in)

Weight

Female: typically 150–350 kg (330–770 lb)
Male: typically 350–650 kg (775–1,430 lb); very large males can weigh to 800 kg (1,760 lb)

Pelage

White, yellowish, or grayish (varies with season and light). Black nose, lips, and skin.

Range

Circumpolar, Arctic: Canada, United States (Alaska), Greenland/Denmark, Russia, Norway (including Svalbard). A few individuals occasionally reach Iceland.

Habitat

Most commonly, annual ice fields over shallow coastal waters. Some occur in the permanent multi-year pack ice (Central Arctic). Increased use of land habitats reported in recent decades, due to sea ice loss.
Den sites for pregnant females are in snow drifts or slopes on land, or less often, on sea ice. Will also den in peat banks in some areas.

IUCN Status

Vulnerable (2015 assessment)

CITES Status

Appendix II

Populations in the Wild

Approximately 26,000 individuals (among 19 subpopulations)

Locomotion

Adapted primarily for walking; conserve energy when moving at slow speeds. Move easily over rugged terrain.

Walk "flat-footed" (plantigrade). Excellent swimmers (use oar-like forepaws) and capable divers (up to 45 ft, though mainly less than 15 ft). Overheat easily when running due to thick fat layer under fur (for insulation against cold).

Activity Cycle

Depends on season; see Activity Cycle.

Social Groups

Generally solitary, except for females with cubs and brief periods during breeding season. Also when feeding at concentrated food resources (e.g., whale carcasses). Adult males may also congregate along the coast while on land.

Communication

Sense of smell well developed. Appear to be sensitive to scent of other polar bears, though role of smell/pheromones not well known.
A few facial expressions reported.
Generally quiet animals (few vocalizations). Females and young cubs communicate with chuffing call. Other vocalizations (e.g., snort, growl) used during agonistic encounters.

Diet

Highly carnivorous diet — mainly marine mammals, particularly blubber and skin of ringed seals. Population size largely determined by ringed seal availability.
Also eat harp, hooded, bearded, and harbor seals. Occasionally, walruses, beluga whales, narwhals, and carcasses of bowhead whales. Other foods taken: various birds and their eggs, reindeer/caribou (in Svalbard, Norway), seaweed/kelp, land plants.

Predators

Humans

Sexual Maturity

Females: 4–5 years, on average
Males: around 6 years of age, but as early as 3–4 years

Gestation

195–265 days

Litter Size

Typically 2 cubs (about 70% of births).
Occasionally 1 or 3 cubs, rarely 4.

Birth Weight

600–700 g (1 lb 5 oz to 1 lb 9 oz)

Early Development

Born November to January. Emerge from den in March or April.

Age at Weaning

About 24 to 28 months. Nurse for at least 1 year.

Typical Life Expectancy

Wild populations: 15–18 years

Managed care: median life expectancy of males is about 21 years

Feature Facts 

• Scientific name means "sea bear"
• Adapted to sea ice, spending only short periods on land
• Thick fat layer and fur to stay warm in extreme Arctic temperatures
• An experienced adult catches a seal every 4 to 5 days
• Massive weight gain before denning sustains polar bears during extended fasting period (up to 8 months for pregnant females)
• Do not eat, drink, or excrete while in dens; body wastes recycled biochemically (not with kidneys)
• Most females reproduce only once every 3 years
• Cubs learn survival skills from mother over their 2.5 years with her
• Polar bear tourism increasing in some areas, such as Churchill, Canada, and Svalbard, Norway
• 1917: first polar bear at San Diego Zoo (one year after opening)
• Threats to polar bears: mainly a warming global climate (loss of sea ice and access to seal prey) and chemical/oil pollution
  • Take action for polar bears