Polar bear behaviours

What do polar bears eat? How many cubs do polar bears have at a time? Do polar bears hibernate? This page will answer these questions as well as others related to different polar bear behaviours.

Polar Bear Diet

Polar bears obtain around two-thirds of their energy for the entire year during the spring. This is when the main source of prey — ringed and bearded seals — is abundant across the entire polar bear range. Seals are nutritionally high in fat and polar bears’ digestive systems have evolved to use high quantities of fat to build up insulation to survive in the cold. Packing on a layer of insulation is important for polar bears, as they fast throughout much of the winter when access to food is limited, frozen under the sea ice.

Polar bears prefer to hunt for seals on thick, multi-year sea as a platform. However, with sea ice extent and thickness decreasing as a result of climate change, polar bears are running into problems. Sea ice retreating earlier in the spring and forming later in the autumn, giving polar bears less time to hunt. This has forced many polar bears to go without food or expend more energy getting food by swimming further distances. This means that the protective layer of insulation they need to survive the cold becomes thinner.

Polar bears mostly eat ringed and bearded seals, but will also eat harped, ribbon, or hooded seals and young walruses. Without access to seals, polar bears look to other food sources, including:

Fish
Seabirds
Waterfowl
Shellfish
Eggs
Small rodents
Larger mammals, such as walrus or reindeer
Carcauses
Berries, kelp or other plants

Polar bears will also seek out garbage that has not been properly stored, increasing the risk of an encounter between people and polar bears, which impacts community safety.

However, none of these alternatives match seals the nutrition in seals that polar bears need to survive.

Polar bear reproduction

Female polar bears have a low reproduction rate — meaning that polar bear populations can be slow to recover from any impacts, such as climate change. Scientists have found that the loss of sea ice impacts polar bear reproduction as well as the adult survival rates.

Female polar bears start to mate between ages four to six years-old. On average, they only produce one to two cubs every three years. Male polar bears start mating between six to 10 years-old, though their prime breeding years begin around age 10. Polar bears typically mate in the late spring and will carry the cubs for around eight months before giving birth. Male polar bears will seek out females by following the scent left by a female’s footprints in the snow. After a male and female polar bear mate, they go their separate ways. Female polar bears look after the cubs until they are ready to survive on their own – around two years.

Do polar bears hibernate?

Unlike many of their bear cousins, polar bears do not hibernate. However, pregnant female polar bears will dig a maternity den to give birth in a warmer, more sheltered place. This typically occurs between October and March. All other polar bears spend their winters hunting seals on the sea ice and rely on their fat reserves during the summer and early autumn.