Alaska Department of Fish and Game Species Profile: Polar Bear

When compared to other bears, polar bears have longer necks, narrower heads, and smaller ears. Their outer coat is white or yellow and made of water-repellent hair, and their undercoat is dense. Its big feet are an adaptation for swimming and walking on ice. Their feet are almost entirely furred.

In terms of body size, polar bears compare to very large brown bears. Males can grow to be over ten feet tall and over a pound and a half in weight, but on average they weigh between 600 and 1,200 pounds. Female adults range from 400 to 700 lbs.

Females are sexually mature when they are 3–6 years old Males reach sexual maturity between the ages of 4 and 5, but they typically aren't productive breeders until they're 6 or older. March through May is polar bear breeding season. On the sea ice, a male can locate a female by following her tracks and scent. The fertilized egg (blastocyst) takes a while to develop after mating, and it doesn't implant in the female's uterus until late September or early October. In the first few months after conception, the embryo develops rapidly, and the pregnancy lasts only a few more. A pregnant female will seek out a denning area, either on land or sea ice, in the months of October and November. It is common for her to dig a hole in the snow near a riverbank, bluff, or sea ice to call home. She will enlarge her lair as snow accumulates into drifts. Twins usually arrive in the world in December or January, and the tiny cubs need to stay safe in the den until they gain a bit more weight.

The cubs emerge from the den in late March or early April, when they weigh 20 to 25 pounds. The cubs need a few days to adjust to the cold weather, so the family will stay close to the den for the first few days. Following this, the family unit will set out for areas in the drifting sea ice in search of food. After about 2.5 years, the mother will re-breed and leave her cubs with another male.

Ecology of Food

For the most part, polar bears eat ringed seals. Bears can easily catch seals if they wait near the animals' air holes. In the winter, they may break into seal lairs (dens) made in the snow and steal females or young seals. Bearded seals, walrus, and beluga whales are also common prey for polar bears. Carcasses of marine mammals such as whales, walruses, and seals are a common source of food for polar bears. The animals will resort to eating plants, bird eggs, and small mammals if nothing else is available.

Migration

Seasonal polar bear migrations can cover great distances, depending on the state of the regional ice sheet. Some polar bears migrate to land along the Beaufort Sea coast of Alaska during the summer melting season to rest until shore-fast ice begins to develop along the coast in late autumn and the pack ice advances south. offering them a platform on which to hunt seals once again

Behavior

Even though polar bears are typically solitary creatures, groups of them may form around marine mammal carcasses.

It is the northern polar region where polar bears are most commonly found. It is not uncommon for polar bears to venture as far south as St. There are times when I leave St. Lawrence Island and travel to the The Kuskokwim Delta and Matthew Island In the summer, bears are most abundant around the edge of the pack ice in the Chukchi Sea and Arctic Ocean The Canadian Arctic, Greenland, Spitsbergen, and the northern Alaska coast are all Denning areas, as is Wrangel Island and other Russian Islands.

Researchers have discovered 19 distinct polar bear populations through mark-recapture, tagging, and genetic studies. The Chukchi Sea population and the Southern Beaufort Sea population are the two Alaskan populations. The area from the northern coast of Alaska into the Canadian Beaufort Sea is home to the Southern Beaufort Sea population. Western Alaska is home to the Chukchi Sea population, which extends from Wrangel Island and eastern Siberia to St. Matthew Island in the Bering Sea to the south.

Dispersal Based on Season

• Polar bears spend the spring months near the pack ice, where they can easily access seals for a hunting platform. In the springtime, pregnant females leave their dens on the mainland or on barrier islands.
• Most polar bears retreat north with the retreating pack ice in the summer. Polar bears will come ashore in Beaufort Sea coastal regions to hibernate until the shore-fast ice forms in late autumn and the pack ice advances south.
• In the autumn, polar bears often travel great distances near the pack ice, depending on factors such as the availability of ringed seals and regional ice dynamics.
• In the winter, near the pack ice In the den, pregnant females give birth to their young.

The polar bear population in the southern Beaufort Sea is in decline, and the fate of the polar bears in the Bering and Chukchi seas is unknown. Since the polar bear's ability to hunt, feed, reproduce, and make seasonal migrations depends on the thinning sea ice, the ESA has placed the species on the list of threatened or endangered species. Visit the ADF&G Polar Bears page for more information.

According to NatureServe, both the global and state populations are vulnerable.
Critically Endangered
ESA: Dangerous

Trends

Throughout the 1970s, the number of polar bears in Alaska steadily decreased. Overharvesting during the legal and widespread sport hunting of the '50s and '60s is blamed for the population drop. After the passing of the Marine Mammal Protection Act (MMPA) in 1972, which prohibited all but subsistence hunting by Alaska Natives, there was a moderate recovery in the late 1970s. In 2015, scientists estimated that there were around 900 bears living in the Southern Beaufort Sea, while the population in the Bering and Chukchi seas was unquantifiable.

Threats

The United States government has taken action in response to the current and predicted decreases in sea ice because S The U.S. Fish and Wildlife Service will submit polar bears for Endangered Species Act (ESA) listing for the entire extent of their range. Reductions in polar bear populations may result from shorter periods of available food due to thinner ice and longer ice-free periods in summer.

Some polar bears may be threatened by oil drilling and exploration because the animals may be forced to relocate from more desirable den sites to those that are less protected. Bears may lose heat insulation and be poisoned if they come into contact with oil during an oil spill. It might also affect their food supply in a negative way.