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Ursus maritimus
Oso blanco, Oso polar (Sp), Eisbär, Polarbär (G), Ours blanc, Ours polaire (F). Also called white bear.
DESCRIPTION (male) Head and body length 7-9 feet (2.1 to 2.7 m). Tail length 3-5 inches (7.6 to 12.7 cm). Shoulder height 4 to 4-1/2 feet (1.2 to 1.4 m). Weight 800-1,000 pounds (360-450 kg), sometimes considerably more. Females are about 25 percent smaller. Chromosome count is 74.
Polar bears are closely related to brown bears; fertile offspring have resulted from polar/brown bear crosses in zoos. Whether the polar bear or the Alaska brown bear is the world's largest land-based carnivore is a matter of conjecture, because few wild specimens of either have been weighed. The polar bear has a streamlined body that has adapted to an aquatic way of life. It has a longer neck than other bears, a relatively small head, long and massive legs, and large feet with hairy soles. The coat is a yellowish-white, which acts to conserve body heat and serves as camouflage in its snowy habitat. Eyes, nose, lips and toenails are black.
BEHAVIOR Solitary except when mating or sharing a large carcass such as a stranded whale. Mating season is from March till June, with implantation apparently delayed several months so that the cubs are born November to January while the mother is in her winter den. The female gives birth every 2-4 years, with a litter numbering 1-4, but averaging two. Cubs remain with the mother 2 to 2-1/2 years. Females are fully grown at five years, males at 10-11 years. Longevity in the wild is estimated at 25-30 years. A captive polar bear lived almost 35 years.
The most carnivorous of all bears, it feeds primarily on ringed seals, with bearded seals the second choice, followed by harp seals and hooded seals. Scavenges carcasses of walrus, whales and narwhals. Will kill other polar bears and, at times, young walrus, and land mammals such as caribou, musk ox, and small animals. Eats crustaceans, fish, birds, eggs and vegetation when other food is unavailable. A great traveler, it roams the pack ice and surrounding seas in search of seals. Polar bears have been observed swimming as much as 40 miles (65 km) from the nearest ice or land. Sometimes swims with all four feet, but more often uses only the forefeet, with the hind feet trailing behind. Swims high in the water, with its head and shoulders exposed, and can attain a speed of four mph (6.5 km/h). If killed in the water, does not sink immediately. Pregnant females den for the winter like other bear species (on shore, often in a hole on a steep mountain slope), but males and non-pregnant females remain active all winter. Sense of smell is excellent and eyesight is adequate. Hearing is good, but polar bears are not alarmed by most sounds because of their noisy environment in the continually grinding icepack.
HABITAT The shores, islands and pack ice of the Arctic Ocean. Mature males often spend years out on the ice, while the pregnant females come ashore to den.
DISTRIBUTION Circumpolar in the Northern Hemisphere, occurring in Eurasia as well as North America. Has been recorded as far north as latitude 88°N and as far south as the Pribilof Islands, Newfoundland, the southern tip of Greenland, and Iceland. There are permanent populations in James Bay and the southern part of Hudson Bay. Still occupies most of its historic range.
REMARKS Polar bears are normally hunted in winter, when the polar icecap is most frozen and the skins are prime. Prior to passage of the U.S. Marine Mammal Protection Act in 1972, most polar bears were hunted from the northwest coast of Alaska with the aid of light aircraft, typically two-place Piper Supercubs with extra fuel cans stuffed behind the passenger. Normally, two airplanes-each with a pilot/guide and a client/hunter-would fly together at low level for hundreds of miles over the frozen ocean, searching for bear tracks. When a large male bear was found, one plane would land (terrain permitting) and the bear would be stalked. A large area could be covered this way and the hunter could be selective taking only old males instead of females. On the negative side, it was dangerous. Planes and lives were lost through engine trouble, running out of fuel, misjudged landings, soft ice or bad weather.
Polar bear hunting in North America today is limited to Canada with Inuit guides and dogsleds. Hunters and guides spend many nights on the ice in tents or igloos, existing under difficult and often dangerous conditions. Bears taken by dogsled tend to be smaller (and often female) because fewer bears are seen. On the positive side, a dogsled hunt on the polar icecap is one of the world's great adventures.
TAXONOMIC NOTES Until a few years ago, five subspecies of polar bears were listed from North America, but most authorities now do not feel they are valid. Other subspecies from Svalbard and Siberia have been named by Russian scientists, but are not generally accepted. We do not separate subspecies for record keeping.
STATUS Since passage of the U.S. Marine Mammal Protection Act in 1972, polar bear hunting in Alaska has been closed to all except native Eskimos, or Inuits, who are allowed unlimited subsistence hunting. In 1973, the five arctic nations (United States, Canada, Denmark, Norway and the former U.S.S.R.) signed the Agreement for the Conservation of Polar Bears. Canada limits hunting to native Inuits, with a quota for each settlement, and allows settlements to sell permits from their quotas to visiting sportsmen and guide them on polar bear hunts. Denmark (for Greenland) limits polar bear hunting to resident Inuits. Norway (for Svalbard) and Russia protect them completely, although it is rumored that Russia may open limited hunting. Unfortunately the U.S. Fish and Wildlife Service (USFWS) has again closed importation of polar bears into the United States starting in 2010.
The world population of polar bears is estimated as 20,000 and is believed to be stable or increasing. The sportsmen's take of polar bears in Alaska during 1971-the next-to-last year hunting was allowed-was about 260, and was much fewer than that in prior years. The yearly worldwide kill by native people is estimated to be about 1,000 (Nowak, 1991). Yet, the polar bear is listed as vulnerable by the IUCN and on Appendix II of CITES (1975). The polar bear has never been listed by the USFWS, which, nonetheless, forbade importation of trophies taken legally in Canada until forced to do so by an Act of Congress, and even then delayed issuance of import permits for more than three years, and now closed.
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