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Partnering

to assess wildlife populations

By Arctic Beringia

May 23^rd, 2024

Nesting Common Eiders in Northern Alaska

Pacific common eiders have been assessed as the highest-risk waterbird population on Alaska's North Slope, largely due to forecasted increases in coastal storm surges that could cause catastrophic flooding in their nesting colonies. Further, barrier islands are increasingly vulnerable to oil spills given the increasing volume of shipping and tourism passing along the coast. Up-to-date information on where important sea bird colonies occur on the coast is important in the event of an oil spill, given the limited capacity to respond in remote areas.

Since 2015, WCS has partnered with U.S. Fish and Wildlife Service to survey 300 miles of Alaska's Beaufort and northern Chukchi Sea coastlines to map Pacific common eider nest density and distribution. Our long-term goal is to better establish the ecological importance and risks to the poorly understood barrier island ecosystems - in particular, to assess which islands are, or will be continue to be, the most critical for nesting birds. It is this niche and those islands that are most at risk from climate change, disturbance, and potential oil spills - and conversely those that need to be prioritized for protection.

Female Common eiders flying along a barrier island. Photo credit Peter Mather.

Field technician Anna Von Duyke 'candling' a common eider egg to observe embryo development. Photo credit Peter Mather.

WCS camp near Icy Cape, Alaska. Photo credit Peter Mather.

A flock of male King and Common eiders. Photo credit Peter Mather.

Two day old common eider neestlings. Photo credit Nika Slade.

Barrier island near Akoliakatat Pass, Alaska. Photo credit Scott Shively.

Eider Population Assessments

Most of the nearly one million King and Common eiders breeding in northern Alaska and western Canada migrate past Point Barrow, Alaska twice annually. This spectacular concentration of migrating birds, perhaps one of the last great bird migrations, passes very close to shore, allowing for population estimates which have been intermittently conducted under varied protocols since the early 1950s. In partnership with the North Slope Borough, WCS coordinated a spring migration count in April and May 2015 and 2016 to provide information on the population trajectories of King and Common eiders migrating past Point Barrow.

The counts were conducted from a grounded pressure ridge close to the edge of the shore fast sea ice northwest of Barrow, Alaska (about 7 miles from land), and then on land near Barrow when the ice degraded. Four observers counted eiders for up to 16 hours per day, in teams of two people at a time. Whaling crews were actively hunting near the perch in both years, and whale remains attracted a considerable number of polar bears. The North Slope Borough bear guard provided considerable peace of mind while observers were busy counting eiders as they streamed past, sometimes as many as 40,000 in 4 hours.