Melting Ice Forces 10,000 Walruses Ashore in Alaska

(Sept. 15) -- Female walruses traditionally like to spend the summer lounging on slabs of sea ice with their young, occasionally dipping into shallow Arctic waters for a fishy treat. But over the past few weeks, thousands of these mammals have given up their free-floating lifestyle and taken up residence along the Alaska side of the Chukchi Sea.

An estimated 10,000 to 20,000 Pacific walruses -- mainly mothers and calves -- are resting along the coastline, gathered together in tightly clustered pods, according to the U.S. Geological Survey. (Bulls normally splash around the Bering Sea in summer months.) Because only 20 percent of walruses normally come to shore, the Alaska Dispatch notes, scientists suspect another 80,000 walruses could be swimming close by. This is the third time such a sea-to-land migration -- common in Russia, but historically unprecedented in Alaska -- has taken place in the last four years.

This unusual behavior appears to have been triggered by the slow warming of the Arctic waters through climate change, which in turn has shrunk the amount of thick, walrus-suitable sea ice. Last week, the U.S. National Snow and Ice Data Center reported that Arctic sea ice coverage had fallen to its third-lowest level since records began in 1979; only 2007 and 2008 saw lower levels.

"As the ice decreases, the walrus are abandoning it earlier and earlier," Geoff York, of the World Wildlife Fund's Arctic program, told The Guardian.

Forced ashore, walruses face new threats -- often from their own kind. "Our biggest concern right now is stampeding," Bruce Woods, a spokesman for the U.S. Fish and Wildlife Service's Alaska regional office, told ClimateWire. "That's the big risk posed to these animals."

These slow-moving walruses traditionally live in groups of up to 500. Living in bigger, more tightly packed pods substantially ups the risks for youngsters, as they're more likely to be crushed by older females, which weigh around a ton each.

Last year, a sudden dash to the water by a pod at Alaska's Icy Cape caused 131 walruses, most of them juveniles, to be trampled to death, ClimateWire reports. Experts suspect that stampede might have happened when the group was spooked, since these beasts -- despite owning a pair of fierce-looking tusks -- are easily scared. In an attempt to prevent more stampedes this year, the Fish and Wildlife Service has asked boats, planes and hunters to keep their distance from the pods.

Life on shore poses other problems for the chunky creatures. USGS scientists are concerned that beach-dwelling walruses, most of which are females, will have to expend extra energy hunting food.

"We suspect it will have real change in the cost of making a living for the walrus," Tony Fischbach, a USGS walrus researcher, told Alaska Dispatch. "Instead of rolling off the ice and having your food right there, they might have to commute."

As beach-dwelling walruses will likely spend more time waddling in and out of the water and swimming in the sea, this new lifestyle could spell trouble for calves. More young walruses -- which rely on a mother's care for two years, and are nursed for the first seven months -- might be crushed, for instance, because their parents will have less time to protect them from lumbering neighbors. And they'll be increasingly vulnerable to hungry polar bears, which are also being driven ashore by melting ice.

Exactly how the walrus population will cope with life in a rapidly changing Arctic still isn't clear. But things aren't looking good for the massive mammals. As the sea ice continues to recede during summer months, it's expected that more ships will sail through their habitat, adding to potential sources of scares and stampedes.

Walruses might also face a shortage of food, as the rising acidification of the Arctic waters will make it steadily more difficult for their clam and mussel prey to build their shells.

That combination of threats led the USGS to conclude in a report last week that there was a 40 percent chance the Pacific walrus could be on the path to extinction by the end of this century.