Retreating sea ice is driving walruses ashore in Alaska, the U.S. Geological Survey said yesterday.

In normal summers, the marine mammals rest on ice floes in between dives to the ocean floor to feed on clams, worms and snails.

But this year, the sea ice in the eastern Chukchi Sea has retreated beyond the edge of the continental shelf into waters too deep for walruses to forage. The animals have started to seek shelter on land, said USGS biologist Chad Jay…

“The ice is very widely dispersed, and there is little of it left over the continental shelf,” he said. “Based on our tracking data, the walruses appear to be spreading out and spending quite a bit of time looking for sea ice.”