Polar bears don't have many predators, but their numbers are still declining due to melting ice caps and humans interfering by killing the bears' main food source: seals. Polar bears are uniquely adapted to life on the ice, having developed the hunting skills and stamina needed to survive the Arctic tundra.
According to Polar Bears International, walking uses 13 percent more of a bear's energy than sitting still. With every calorie important to survival, polar bears have developed the ability of "still hunting" -- lying patiently for hours as they wait for their prey. They sniff out holes in the ice dug by seals, then sit beside the hole until a seal pokes its head up to breathe. The bear grabs the seal quickly and pulls it out of the water.
Even though the water is icy, polar bears are skilled swimmers. Healthy adult polar bears can swim for several days without stopping. They swim from the mainland to large, floating ice islands that have broken away. Seals often rest on these islands, and the polar bears can swim up quietly and pounce fiercely up on the ice before the seal can react.
Although polar bears are masters of still hunting, they can reach speeds of 25 mph for short bursts. A polar bear approaches a seal quietly, then charges when he's within 50 to 100 feet of the seal. For this short distance, he can move so fast the seal doesn't have much time to react and reach the safety of the water.
Traveling Over Ice
Moving around on the ice can be treacherous, but polar bears have perfected the skill of ice travel. The bottoms of their paws are covered in hair to keep them warm and provide extra traction. A polar bear might travel more than 1,800 miles during a year, migrating to follow the food supply. Their thick, muscular legs help them climb snow-covered banks, and they are excellent jumpers. Polar bears must jump over large cracks that develop in the ice, especially in the warmer months, and they can leap over cracks as wide as 19 feet.