Long a symbol of the effect of climate changeon animals, few scientists are optimistic about the future of polar bears (Ursus maritimus). Polar bears rely primarily on the strength and surface area of sea ice, but as polar ice becomes smaller and less stable, they are coming under increasing threat.
Did you know? Polar bears have big feet that let them distribute their weigh evenly across snow or thin ice.
Native to the Arctic, polar bears are found most commonly on the edges of large masses of polar ice. What draws them to the edges of the arctic ice? Their prey, in fact. Seals, which make up the majority of the polar bear’s diet, routinely come up for air or stretch themselves on the edges of ice floes, providing polar bears a perfect hunting opportunity.
How They Live
Polar bears live solitary lives, though they have sometimes been seen playing together for hours at a time. When they hunt they are amazingly stealth. When hunting, they will wait near an ice hole or where the ice meets the water for a seal to come up for air. The polar bear can smell the seal and will reach its large paw into the water to scoop the unassuming victim out.
What role does the polar bear play in its ecosystem? Foxes and gulls rely on large, healthy populations of polar bears for their own survival. These animals routinely feed on the leftovers a polar bear leaves behind from his or her hunt.
Mating happens in the same locations, on the edge of the sea ice near the best hunting areas. Males track the females down and mate numerous times over the course of a week – in the subsequent months, a pregnant female will eat large amounts of food, sometimes adding as much as 200 kg to her usual body weigh to support her cubs.
Mating begins in the spring. By the fall, when a pregnant female is fatter, she will dig a den and will settle down until the birth of her pups – usually two to a litter. Drawing on her recently acquired weight, the mother will nurse the cubs until they are as much as two and a half years old. Approximately 45% of the cubs will survive this during this period – a statistic that has declined steadily over the last two decades. For those who reach this age, they are ready to be sent into the Arctic by themselves.
Threats to the Polar Bear
IUCN identifies climate change as the most significant threat to the survival of polar bears – in large part because as polar ice melts it both reduces the area they have to live in and threatens their ability to hunt for food.
Although specific numbers are hard to come by – polar bear populations are notoriously difficult to study – most scientists believe there are between 20,000 and 25,000 worldwide. However, the populations are expected to decrease based on the evidence available on the future of the Arctic’s ice sheets. The unfortunate fact is that, according to conservative estimates, within 100 years, polar bears may not be able to survive in the Arctic at all.