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Polar Bear

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Polar Bear

Facts about the Polar Bear

 Family: Ursidae
Length: 2.4 to 2.6 metres
Weight (average): males 500 kg, females 250 kg
Sexual maturity: 4 to 5 years
Lifespan: 20 to 25 years

  • Long massive body
  • Highly-developed sense of smell and sight
  • Sharp non-retractable claws
  • Partially webbed feet

The Polar Bear (Ursus maritimus) is Earth’s largest land carnivore. Being well adapted to living on Arctic sea ice, it is however considered a marine mammal. Worldwide, polar bear populations are distributed mostly between Canada and Alaska. Polar bears are also present in Greenland, Norway and Russia. 

Well-adapted paws and claws

Ours polaireThe Polar Bear moves with great ease through the water. Its enormous forepaws propel it forward, while the hind paws function as rudders. On snow, the paws serve as snowshoes, and on ice the claws act like spikes, improving traction.

 

Well-insulated body

Beneath the Polar Bear’s coat lies a hidden black skin that holds in the sun’s heat. The dense fur, combined with a thick layer of fat, protects the bear from the harsh Arctic climate. The Polar Bear will brave temperatures of -40 C, but is uncomfortable when the mercury climbs above 10 C. It is so thoroughly adapted to Arctic conditions that even minor changes in its environment put it at risk.

Off-shore food store

The Polar Bear’s life is closely bound to sea ice. The extent of ice floes covering the sea determines the size of its hunting territory. When ice in certain regions melts in summer, the Polar Bear must return to land. With no seals to eat until the ice returns, it must rely chiefly on its reserves of fat to survive.

Featherweight cubs

Polar Bear couples mate in April and May. However, the fertilized egg does not implant in the uterus and begin to grow until mid-September to mid-October. In the fall, the female digs out a den in the snow, where she will give birth. Cubs are born in the den at the beginning of winter, between November and January, following two months of gestation. The cubs, generally born in pairs, weigh less than kilogram at birth. Fortunately, the mother’s milk, rich with fat, makes them develop rapidly. 

Growing up on the ice floes

At the first signs of spring, around the age of 12 weeks, the cubs leave the den with their mother to explore the ice floes. Here they learn the basics of hunting and survival. The mother feeds the cubs during this period, and must occasionally defend them against famished adult males. Around the age of three years, the young bears begin their adult life.

Stalker of seals

When hunting, the Polar Bear relies on its extraordinary sense of smell to locate prey. It can detect a seal from over one kilometre away or beneath a thick layer of ice. A formidable predator, it lies in wait near an air hole, and as soon as a seal emerges to breathe, it delivers a fatal blow with its paw. Seals make up 90% of the polar bear’s diet, however, if the occasion arises, it can also make a satisfying meal out of a walrus or a beluga.

Survival in jeopardy

Ours polaireHunted for 300 years, polar bear populations suffered significant decline until an international agreement, signed in 1976, provided for their protection. Today, the threat comes from global warming. The melting of sea ice has greatly reduced the length of the seal hunting season, and the ruler of the Arctic is having difficulty rebuilding its fat reserves. Within a century, this species could become extinct.

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Links
Environment Canada Field Projects: Polar Bears
Ressources naturelles et faune Québec (French website)
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