ADOPT A POLAR BEAR
Not federally listed as endangered or
threatened. The International Union for
Conservation of Nature (IUCN), Polar
Bear Specialist Group lists most
populations as "stable."
The polar bear rivals the Kodiak
bear as the largest four-footed
carnivore on Earth and can live
up to 25 years. Although the polar
bear’s coat appears white, each
individual hair is actually a clear hollow tube that channels the sun’s energy directly to the bear’s skin and helps it stay warm. The polar bear’s entire body is furred, even the bottom of its paws. That helps prevent bears from slipping on the ice. The polar bear is classified as a marine mammal. Its feet are partially webbed for swimming, and its fur is water-repellent. A formidable predator, it has extremely sharp claws.
Males are 8 to 11 feet long and weigh 500 to 1,100 pounds but can reach as much as 1,500 pounds. Females are smaller, measuring 6 to 8 feet long, and weigh from 350 to 600 pounds, occasionally reaching 700 pounds.
Worldwide there are thought to be 22,000-27,000 polar bears in 19 separate populations. They can be found in the United States, Canada, Russia, Greenland and on the Arctic islands of Norway. There are estimated to be about 3,000 to 5,000 polar bears in Alaska.
Polar bears are found throughout the Arctic and are the most nomadic of all bear species. They travel an average of 5,500 miles a year or 15 miles a day. In the United States, polar bears are located in two Alaskan populations: the Chukchi/Bering Seas of western Alaska and the Beaufort Sea off northern Alaska.
The entire circumpolar Arctic region is polar bear habitat. They are equally comfortable in the water and on land. Polar bears can be found on pack ice, coastal islands, coastlines and even out in Arctic waters. They are exceptional swimmers and have been observed in the sea more than 100 miles from the nearest land or pack ice.
Polar bears are strictly carnivores and feed or scavenge only meat. Their primary prey is the ringed seal though they also take bearded, harp and hooded seals and the occasional walrus youngster. They will also scavenge walrus and whale carcasses. That sometimes results in temporary aggregations of polar bears at such sites. Other species, such as the Arctic fox, rely entirely upon "polar bear left-overs" after the bears have eaten their fill of seal skin and blubber, leaving the remaining meat for such scavengers.
The two main focuses of this solitary creature's life are to conserve energy and to hunt. Only pregnant females dig dens and hibernate in the traditional sense for extended periods. The other bears may enter into what is referred to as "walking hibernation" where they remain active and continue to hunt and feed, even though some of their metabolic processes may slow (decreased heart rates, respiration, lowered temperatures, etc.). Polar bears depend mostly on their sense of smell to determine the location of prey. Their white coats make great camouflage for hunting seals, and they will wait patiently for hours next to a seal’s air hole waiting for the seal to take a breath. Once the seal arrives, the polar bear will use its immense strength and sharp claws to clutch the seal and drag it through the small blowhole.
Females are able to breed at the age of five years. They dig dens either on the coastal mainland or out on the drifting pack ice in late October or early November, and then remain denned until the next spring. An average of two cubs are born, each weighing about 1 pound at birth and growing to about 15 pounds by the time they emerge in the spring. The cubs have much to learn and usually remain with their mothers for more than two years.
The primary threat facing polar bears today may be global warming. Scientists have already documented measurable effects in the body sizes and reproductive success of bears at Hudson’s Bay. This southern-most population of polar bears has adapted to an ice-free summer by moving onshore at Churchill, Manitoba, and fasting through the short summer season until freeze-up occurs, and the bears can return to the ice. Global warming has resulted in prolonged ice-free periods, and the polar bears are left stranded onshore for longer and longer periods. Break-up in the spring occurs an average of 10-14 days earlier than 20 years ago and was four weeks earlier in 1999. Scientists estimate that for every week of delay in freeze-up, polar bears lose at least 22 pounds of critical fat reserves. Pregnant females are losing so much weight that they fail to produce enough milk for their cubs, which then suffer increased mortality. Once females fail to attain a minimum weight they won’t give birth at all, and scientists can already document a 15 percent drop in birth rates.
Another globally produced impact to polar bears are chemical pollutants that find their way into the cold Arctic ecosystems and then never disappear. Such chemicals as PCB’s (polychlorinated biphenyls), banned from the U.S. plastics industry since the 1970s, concentrate in the blubber of prey species that are then eaten by the bears. Such concentrations of these and other toxins are linked to immune deficiencies and generally reduced fitness in some polar bears.
The third threat of note is the proposed oil and gas development on the Arctic National Wildlife Refuge in northeastern Alaska. This is the most important onshore denning habitat for polar bears in the United States. About half of the bears from the Beaufort Sea population den onshore, and half of these select the refuge’s coastal plain. This is the very place proposed for oil exploration. Both the seismic exploration phase and an eventual oil extraction phase could introduce serious disturbances that may result in den abandonment and death of the offspring.
CITES* Appendix II, U.S. Marine Mammal Protection Act, Agreement on the Conservation of Polar Bears.
*Convention on International Trade in Endangered Species of Wild Fauna and Flora, an international treaty with more than 144 member countries. Appendix I listed species cannot be traded commercially. Appendix II listed species can be traded commercially only if it does not harm their survival.