Polar Bear

Polar bears prey on ringed and bearded seals, which they can only catch from a platform of sea ice. They will take advantage of other food sources, like belugas and carcasses, when available. Polar bears need foods high in calories to maintain the thick layer of fat that keeps them warm, so seal blubber is the ideal food source. Bears that have constant access to sea ice can hunt throughout the year. However, those in areas where the sea ice has retreated or melted completely each summer are forced to spend months on land. Here, they primarily fast on stored fat reserves and try to take advantage of non-natural food sources.

At the Columbus Zoo and Aquarium, the polar bears receive a variety of raw meat and fish, formulated polar bear chow, bones, and other enrichment in the form of novel foods.

The polar bear is found throughout the circumpolar Arctic in the five “polar bear nations” of United States (Alaska), Canada, Russia, Denmark (Greenland), and Norway. The polar bear's southern range is limited by the amount of sea ice that forms in the winter because polar bears prefer to travel on sea ice.

The polar bear inhabits Arctic sea ice, water, islands, and continental coastlines. It prefers sea ice habitat with leads, next to continental coastlines or islands. Leads are water channels or cracks through the ice, which may remain open (ice-free) for only a few minutes to several months, depending upon weather conditions and water currents. Polar bears hunt seals in the leads, using sea ice as a platform.

Other polar bears and humans are the only predators of this species. Male polar bears will predate on cubs, so females with young will avoid other bears for this reason. Historically, native peoples of the Arctic have hunted polar bears for meat and fur.

The largest threat to the polar bear is climate change, as the higher temperatures and erratic weather variations influence many aspects of the species’ lives. Sea ice loss has a huge impact on a polar bear’s ability to find food, reproduce, and move throughout the habitat. Less access to sea ice has resulted in longer fasting periods for bears and increased contact with humans as they look for unnatural food sources, like garbage. Increased human activity in the polar bear’s native range also results in the disruption of polar bear denning habits and an increased likelihood of bears encountering humans.

The polar bear is the largest land predator in the world. It ranges in color from pure white after a molt to a yellowish shade resulting from solar oxidation or staining by oil from seal blubber. A polar bear's fur is not white: each hair is pigment-free and transparent with a hollow core. The fur consists of a dense undercoat topped by guard hairs of varying lengths. The skin, nose, and lips are black. The front paws are broad and make excellent paddles for swimming. The soles of all four paws are covered in fur, acting as both insulation and traction while walking on ice and snow. Polar bear paws are very large and can spread their weight out to keep them from falling through thin ice. A thick layer of insulating fat keeps them warm and helps keep them afloat in water. They are stocky in build with a head that is smaller than other bears, with an elongated neck. This body shape keeps them streamlined in the water.

Polar bears have an excellent sense of smell, but their hearing and vision are not as strong. They utilize their nose and sensitive whiskers to explore their environment.

A female polar bear will have her first set of cubs between the ages of four and eight (most frequently at age five or six). Polar bears have one of the slowest reproductive rates of any mammal, with a female typically producing five litters in her lifetime. Polar bear mating season is in the late winter and early spring, but the actual implantation of the embryo does not happen until early winter, delaying the development of the fetus. This type of reproduction is called “delayed implantation” and allows a female to become pregnant when food supplies are best and when she is in good physical condition. The abundance of food determines whether a pregnancy will be maintained and the number of young that will be born. Females will often not produce young if food is scarce. A pregnant polar bear needs to eat a lot in the summer and fall to build up enough fat reserves for surviving the denning period.

During denning, she gives birth to one-pound cubs and then nurses them to about 20-30 pounds before emerging from the den in March or April, but does not eat. There are usually two cubs in a litter. At birth, the cubs are blind, toothless, and covered with short, soft fur. They are completely dependent on their mother for warmth and food. Polar bear cubs normally stay with their mother until they are 1.5 to 2.5 years old. During the time that the cubs are with their mother, they must learn how to hunt and survive in one of the Earth's harshest environments.

Polar bears can be very vocal. They will often greet each other using a “chuffing” sound.

Polar bears are solitary, except during breeding, while raising cubs, or when interacting near a food source. They are excellent swimmers and may swim exceptionally long distances in search of food. Sometimes for multiple days and hundreds of miles!