It’s hard to believe I haven’t written about polar bears yet. I think partly it’s because I try and focus on more obscure animals, but still, polar bears definitely deserve their own blog post. It worked out especially well for today because I was looking for an animal to draw with white pencil on black paper, and polar bears fit perfectly.
In case you didn’t know, polar bears live in polar regions, specifically in the Arctic. They are found in Greenland, Norway, Russia, Alaska, and northern Canada. Polar bears are actually considered marine mammals, as they spend much of their time at sea. They are also known for travelling great distances over land, as ice melts and then reforms.
Polar bears are some of the biggest bears in the world; their only competitors being Kodiak bears, a subspecies of brown bear. Male polar bears are quite a bit larger than females, weighing an average of 385 to 410 kg, while females weigh only 150-250 kg. The largest polar bear ever recorded weighed an astounding 1,002 kg. Polar bear fur appears white or yellowish, but is actually transparent and hollow, the white colour a result of refracted light.
I don’t think living in the Arctic would be much fun, but polar bears are wonderfully adapted to their frigid environment. Their skin is black, to absorb as much heat as possible from sunlight. Like most animals that live in cold climes, polar bears have small ears and tails, so as little heat is lost through them as possible. They have two layers of fur for insulation, and an additional 10 cm layer of fat that helps them keep warm. All these adaptations mean polar bears don’t do well in warm weather — in fact they start to overheat at temperatures above 10 degrees celsius.
Polar bears are also excellent swimmers. They have extra large feet that are used to propel the bears through the water, as well as distributing weight while the bears are walking on snow or ice. Their feet have small bumps on them to increase grip on ice. Polar bears’ thick layer of fat is also useful when they are swimming, as it provides buoyancy. Polar bears can swim for days on end, moving at 10 km/h.
Polar bears are meat eaters, and are in fact the most carnivorous members of the bear family. They feast primarily on ringed and bearded seals. The bears hunt seals when they come to air holes in the ice to breathe, or when seals pull themselves out of the water to rest. Using their excellent sense of smell, polar bears are able to locate seal breathing holes from 1.6 km away. A bear will wait by the breathing hole, sometimes for hours, until a seal comes up to breathe. When a poor seal does show up, the bear reaches in and drags the seal out with its paw.
Adult polar bears will often only eat the skin and blubber of the seal, which are digested easily and are calorie-dense. Younger bears can’t afford to be as picky, and will eat the meat of the of the seal as well. Polar bears do attack land animals as well, though seals remain the most important part of their diets. During the summer, when there is no pack ice for the bears to hunt from, polar bears are food-deprived, as they cannot get enough calories from non-seal food sources.
Mating in polar bears takes place in the spring, in April or May. Group of bears will gather around good hunting spots, and males will fight for the right to breed with females. Once a male and female have paired up, they stay together and mate for about a week. Fertilized eggs have their development suspended until the late summer. During this time, female polar bears eat and eat, generally doubling their body weights.
Females dig a maternity den in the fall, in snowdrifts or underground. They enter a hibernation-like state until the young are born, in November to February. At birth, polar bear cubs are blind and weigh around 600 grams. Litter sizes range from one to four, though litters of two cubs are the most common. The family emerges from their den between February and May. At this time the cubs weigh between 10-15 kg. They stay with their mother for two to three years, learning from her actions as well as through play. Mother polar bears are known to be excellent guardians, and are very protective of their offspring. So don’t ever get between a polar bear mother and her cubs!
Despite their size and carnivorous nature, polar bears will generally choose to flee rather than fight. Attacks on humans do happen, but these are driven by hunger, not due aggression from the bear. So I guess if you run into a polar bear in the Arctic, you’d best hope it had a tasty meal recently. Polar bears, of course, are the poster children of climate change, as they rely on ice packs to hunt and survive. They are currently listed as a vulnerable species, thanks to the decline ice in the Arctic. They are amazingly beautiful and wonderfully adapted animals, and hopefully we can keep them around for a while to come.