Polar bears take up rock-climbing to find eggs

Yum-yum: this polar bear spotted on Coats Island in northwestern Hudson Bay proved to be a nimble climber, scaling a near vertical cliff to reach the nests of thick-billed murres and eat eggs. (PHOTOS BY KERRY WOO)

Polar bears are ready to climb steep bird cliffs in search of food, say wildlife biologists, who suggest recent sightings of rock-climbing, egg-eating bears in northwestern Hudson Bay are linked to the retreat of sea ice in that region.

Hungry polar bears can cause extensive damage to snow goose and thick-billed murre colonies when they come ashore before the birds’ eggs have hatched, said wildlife biologist Paul Smith.

The marauding polar bears stuff themselves with huge numbers of eggs, Smith said in an April 28 interview from Ottawa.

This pillage of bird colonies appears to be a new phenomenon. That’s because there have few recorded observations of polar bears doing this until recently— and likely snow geese and murres wouldn’t nest in colonies if polar bears always wiped them out, he said.

In 2004 on southern Southampton Island, a well-nourished adult female wandered from nest to nest in a snow goose colony, scooping up the entire contents of each nest, noted Smith and co-authors in a paper from a recent edition of Polar Biology.

The polar bear stayed the area for a few days, wiping out some 400 nests.

“Usually the bears eat the whole eggs, shell and all. Sometimes they’ll crush them and lick up the goo, but they mostly just gobble up the eggs,” Smith said.

“What you’ll see across the tundra is they leave piles [of their feces] like giant oil slicks of black goo.”

In another incident from June 2006 on Coats Island, also cited in Polar Biology, biologists counted five polar bears in a goose nesting area, where they proceeded to eat the entire contents of each nest, before they walking on to the next.

The polar bears appeared to recognize the scent of the nests, several metres from each other, and search them out.

Within a week, they managed to finish off eggs from most of the 350 snow geese nests.

“You can imagine the number of eggs you can fit in a bear — one bear can easily consume the eggs from hundreds of geese. If this were to happen across the North, it could be significant,” Smith said.

A lone polar bear climbed on to cliff ledges used by nesting thick-billed murres and ate all the murre eggs— and chicks— around in two other incidents on Coats Island from July of 2000 and July of 2003, notes the Polar Biology paper.

Eggs have always been around in these cliffs in the past at the same time as polar bears, Smith said.

“We never saw bears eat these eggs, so it implies they aren’t so keen to climb the cliffs unless they have to,” he said.

The polar bears’ new habits are likely linked to their trouble in capturing prey out in the open water.

Polar bears usually draw on their stored fat throughout the ice-free period.

If they’re hungry, they may also feed on grasses, marine algae, berries, carrion, remains from human hunting, as well as occasional caribou, fish, rodents and birds.

The willingness of polar bears to tackle cliffs shows the lengths to which they may go to supplement their diet during a longer ice-free season, conclude Smith and his co-authors in their paper.

This egg-eating by polar bears wouldn’t happen further to the north where polar bears can still spend the summer on drifting ice and don’t arrive on shore until after the birds have hatched, Smith said.

As for being a nifty adaptation to a changing climate conditions, egg and chick eating won’t take polar bears very far, he said, because it takes too many eggs to fill a bear— and they would eventually run out of birds.