A studious-looking and threatened sea duck won't be run over by a Russian fuel tanker slicing through the sea ice to Nome, thanks in part to federal satellite data tracking the duck's whereabouts.

The ice-class tanker Renda, with help from the U.S. Coast Guard's only functioning icebreaker, the Healy, is plowing through the Bering Sea pack ice to deliver 1.4 million gallons of fuel to the ice-locked town in Northwest Alaska.

That same pack ice is the winter home of the spectacled eider, a clam-eating, football-sized duck distinguished by a white eye ring resembling spectacles. The duck spends several winter months in the northern Bering Sea, diving for sea-bottom clams through openings in the pack ice.

The U.S. Geological Survey learned where they wintered about 20 years ago after implanting the eiders with satellite transmitters. Biologists were surprised to learn that nearly the entire population, which breeds in summer along Russia and Alaska coastlines, migrated to the northern Bering Sea in winter, said Matthew Sexson, a USGS biologist.

"We had no idea," Sexson said. "We thought they occupied leads near the coast."

Nearly 400,000 eiders winter in the region for five to six months, surviving brutally cold temperatures thanks to their super-insulating eider down and oil-secreting glands that help them shed water from their feathers.

Now, federal officials will use more recent satellite telemetry data to pinpoint the ducks' location and protect them from the unprecedented winter fuel delivery.

Because the ducks are classified as threatened under the Endangered Species Act, the Coast Guard consulted with the U.S. Fish and Wildlife Service to inform them that the January delivery might be plowing through the duck's turf. Then Fish and Wildlife turned to the USGS to determine the bird's winter habitat, Sexson said.

The agencies are working together to "plot a route that minimizes impacts to the species," said a USGS press release issued on Friday. The ducks are now south of St. Lawrence Island, feeding on clams and other invertebrates.

Their location isn't an issue now, because the Renda is heading for Nome from Dutch Harbor. But it will be useful as the ship leaves Nome and cuts a path back toward its home port in Russia.

Contact Alex DeMarban at alex(at)alaskadispatch.com