Wildlife

International Polar Bear Day

Today is International Polar Bear Day. Here are some facts about the furry beasts.

An adult male polar bear typically weighs between 775 and 1,200 pounds (351 to 544 kilograms), or the weight of about five to seven men. The largest polar bear ever recorded was a male weighing 2,209 pounds (1,000 kg), according to Polar Bear International. By contrast, adult females weigh only half as much as males, or 330 to 650 pounds (50 to 295 kg). But the bears are tiny when they're born, weighing only about 1 pound (0.5 kg). Males reach their adult size between ages 8 and 14, while females reach full size between ages 5 and 6.

If a polar bear doesn't eat for seven to 10 days, it can slow its metabolism until it finds its next meal. They survive off of fat reserves from their diet, which consists mostly of ringed and bearded seals. (But climate change is making food more scarce and driving some bears to cannibalism.) The bears don't hibernate, but mother bears live in dens while they raise their cubs. While mothers are in their dens (generally between January and March), they don't eat, drink or defecate.

Although polar bears appear white, their fur is actually transparent. It only appears white because it reflects visible light. Under their fur, polar bear skin is actually black. To humans and other animals that can only see in visible light, the bears appear to blend in with their snowy surroundings. But reindeer, which polar bears sometimes prey on, can see in ultraviolet light, which makes polar bears stand out from their snowy environment.

Polar bears have a keen sense of smell, which they use to find prey. A polar bear can sniff out a seal on the ice 20 miles (32 kilometres) away, and can smell a seal's breathing hole in the ice more than half a mile away, according to the National Zoo.

Polar bears rely on sea ice to hunt, and studies predict that global warming could melt enough sea ice to make two-thirds of polar bears disappear by 2050. The decline in sea ice has forced the bears to swim longer distances, consuming energy they cannot afford to use.