Shifts in the distribution of Spectacled Eider, a threatened species, indicate possible changes in the Arctic’s marine ecosystem, according to new research published in The Condor: Ornithological Applications.

A team led by wildlife biologist Matt Sexson, of the USGS Alaska Science Center, equipped adult eiders with satellite transmitters between 2008 and 2011 and compared the telemetry data with data from the mid-1990s.

The species was listed as threatened under the Endangered Species Act in 1993 as a result of huge declines in the breeding population in western Alaska, as much as 96 percent from 1952 to 1993. Genetically distinct breeding populations also occur in northern Alaska and northern Russia.

Spectacled Eiders molt primarily in four areas: in the East Siberian Sea, between the Indigirka and Kolyma river deltas on the northern coast of Russia; in Ledyard Bay, in northwestern Alaska; in Norton Sound, on Alaska’s west coast; and the Mechigmenskiy Gulf, in eastern Russia.

Climate change in the Arctic

Sexson and his team found that the birds had shifted their range significantly in two of the four molting areas. The researchers interpret the shifts as an indicator of ecosystem change — eiders go where their prey is, and their movements could indicate big changes in the community of the bottom-dwelling, cold-water-dependent invertebrates that the ducks eat.

It’s easier to track marine predators than it is to track their prey, explains Sexson. “It’s tough to speculate on the connection with climate change because the data are so sparse, but we know that the North Pacific is changing,” he says. “There’s a lot of corresponding evidence that together all says something big is happening here, and eiders provide a readily available indicator that changes are occurring.”

Sexson and his colleagues spent months at a time in the remote Arctic to catch eiders on land during their breeding season, luring them into nets before making a two-hour trek back to base camp with each bird to surgically implant a satellite transmitter.

Jackie Grebmeier, a research professor at the University of Maryland’s Center for Environmental Science and an expert on Arctic marine ecosystems, called the study “another piece in the puzzle” of ecosystem change in the Pacific Arctic region.

“The results of this research provide an important finding of biological response of an upper-trophic-level seabird to climate warming and sea ice retreat.” As Arctic water warms, whole communities of animals are moving north — and there’s only so far they can go, she says.

Study: Climate change is causing bird distributions to shift faster than expected.

Read an article about birding Alaska’s Yukon Delta refuge.

See reader photos of eiders.

 

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Originally Published June 1, 2016