The Polar Bear’s Dilemna

There's a reason she looks uncertain

There’s a reason she looks uncertain

This is the mother of the twin polar bear cubs WC posted last week. And there’s a reason she looks so uncertain.

She is the sole source off nourishment for her cubs; they depend upon her milk to survive in the arctic environment. While she carried a lot of fat when she denned, birthing two cubs and then feeding them her milk for nine months has left her thin and hungry. She’s not going to restore her lost weight scavenging the beaches of Barter Island, even at Kaktovik’s world-famous whale bone dump.

She is in a race against time. She needs the shore fast ice and pack ice to freeze, so she can get out on the ice to hunt seals, her favored prey. She needs that to happen before hunger makes her milk stop, and her cubs starve. As the dates of sea ice minimum – the date on which the sea ice has retreated furthest – get later and later, and the pack ice further and further from shore, the longer she must wait. And the greater the risk of the cubs dying. While adult polar bears can swim long distances, the young cubs are less skilled, have less stamina and are more likely to drown. And with them will drown the future of the species. As Alaska’s polar bear expert, Steve Amstrup puts it,

Ultimately, however, if sea-ice cover continues to decline, polar bears worldwide will suffer. Polar bears are so closely tied to the presence of the sea-ice platform from which to hunt, mate, and carry on other life functions that continuing extensive declines in ice coverage will restrict their productivity and could ultimately threaten their survival.

– Steve Amstrup, “Polar Bears, Ursus maritimus

Polar Bears are slow breeders, and don’t breed at all if prey is not available. A useful trait in a normal world, it may be their undoing in the the Anthropogene, the Anthropogenic Era. And may lead to the extinction in Alaska, and possibly the world, of the planet’s largest land predator.