Polar Bear Facts
Scientific name: Ursus maritimus
Names in other languages:
Ours Polaire (French)
Beliy Medved (Russian)
IUCN status: Vulnerable
Population: 26,000 (best estimate from IUCN scientists)
Life span: 15 - 20 years (wild), mid 20's - 30 years (human care)
Size: Males 350-600kgs, females 150-290kgs
The North! Polar bears live on Arctic sea ice (not Antarctic). They can be found within five different countries - Canada, US (Alaska), Greenland, Norway (Svalbard) and Russia. Their range is divided into 19 different sub populations, with the closest to us being the Southern Hudson Bay population.
Biology and Ecology
High calorie seal blubber makes up the majority of a polar bear's diet. Using the frozen sea ice as a platform from which to hunt, polar bears utilize their keen sense of smell to locate their seal prey. They will wait patiently at breathing holes or along the edge of an ice floe for an unsuspecting seal to pop their head up to breath. Lightening fast reflexes and wide jaws allow the bear to reach in and pull the seal up onto the ice to be eaten. As skilled as polar bears are, hunting success rates are low, approximately only 2 out of every 10 hunts ending in a caught seal.
Polar bears may also hunt for beluga whales or narwhales, but this is far less common than their primary target of ringed seals. Large groups of bears have been observed feeding on whale carcasses which wash up on the shore in the summer, providing valuable nutrition at a time in which food can be scarce.
Polar bears breed in the Spring. Males use their strong sense of smell to seek out females, often following the scent left behind by their foot prints in the snow. Male and female polar bears will stay together for a couple of weeks, in which time they will breed multiple times. Following this, the bears will part and the male will have no part in raising the cubs.
Following a successful breeding, the female will go through a time called delayed implantation, where the fertilized embryo will not implant or begin to grow straight away. Rather, it will 'float' until the Fall, when the female will dig a den in which to give birth. Females will give birth to 1-3 cubs, weighing little more than one pound! The cubs will stay in the den until March or April, drinking their mothers fat-rich milk and growing quickly.
Once emerged from the den, cubs will stay with their mother for the next two years. In this time, cubs will learn the valuable skills needed to survive in the Artic.
The fur of a polar bear provides the perfect protection from the harsh arctic elements.. and is not actually white! They have two layers of fur; a dense under layer for warmth and a long outer layer, called guard hairs. Each hair shaft is hollow, transparent and lacks pigment, meaning polar bears aren't actually white!. They appear white because of the light entering the hair shaft, which scatters and reflects - a similar process to how snow and ice look white. Polar bears appear most white after they have shed in the spring, as the older fur can develop a yellow hue from the oils in their skin.
Their fur is so effective at keeping in warmth that polar bears can overheat quickly when they run, even in the winter.
Under their thick fur, polar bears have black skin! The easiest place to see their skin is on their nose and the pads of their feet, which are the only areas of their body not covered in fur. Science does not yet understand why polar bears have black skin, but the leading theories are to protect them from sunburn or to absorb warmth from the sun.
Polar bears have large feet, measuring up to 30cm across, which help to distribute their weight when walking on ice. Each foot has five claws which they use for catching and gripping their prey, as well as traction. The foot pads on the underside of each paw are covered in small bumps called papillae which help to prevent the bears from slipping.
Their large feet are also effective tools when swimming, with the front feet acting like paddles while the back feet hang and act as rudders.
To help keep them warm, especially when in water, polar bears have a thick layer of fat which can measure up to 11cm. Covering this layer of fat is their skin, which is actually black! Small ears and a small tail help to conserve body heat and reduce heat loss.