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
Biology and Ecology
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.
High calorie seal blubber makes up the majority of a polar bear's diet. They use the sea ice as a platform from which to catch seals, often unsuspecting when coming up to take a breath.
The 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 scare.
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 protection from the elements and is not actually white! Polar bears 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. 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.
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.