Population Trends of King & Common Eiders

Principal Investigators Robert Suydam, Ph.D.
Collaborators UAF (Lori Quakenbush, Rebecca McGuire, Abby Powell, Laura Phillips, Mike Knoche, Steffen Oppel)
Funding Alaska Department of Commerce, Community and Economic Development, Coastal Marine Institute (CMI), NSB


King (Somateria spectabilis) and Common (Somateria mollissima) eiders are important subsistence species in Alaska, Canada and Russia, yet relatively little was known about their population size, trends, movements or breeding biology. The NSB initiated studies in the 1990’s to help fill these data gaps.

The eiders that migrate through northwest Alaska nest at dispersed locations across northern Alaska and Canada. Because they are widespread it is difficult to get a good population estimate. Most of the population, however, migrates near Barrow during the spring and then again in the summer/fall. We counted eiders and other birds as they migrated past Barrow. Surveys in the late 1990s suggested that both species had declined by about 50% when compared to counts conducted before 1990. Estimates for the number of birds migrating past Point Barrow in 1976 were about 800,000 for King Eiders and 156,000 for Common Eiders while the 1996 estimates were about 350,000 and 72,000, respectively. It is unknown why the populations declined but may have been due to changes in environment, especially in wintering areas. More recent counts have suggested that the populations are now increasing.

Aerial surveys showed that the King Eider population had declined, but very little was known about its breeding biology or specific migration routes or habitat use at sea. Several studies were initiated to learn more about the breeding biology, including reproductive success and habitat selection and use, of King Eiders. Comparisons were made in timing of nesting, nest success, and habitat use between an undeveloped site near Teshekpuk Lake and a developed site near Kuparuk oilfield. Results suggested that the human activity at the Kuparuk site had little influence on hatching success of eiders. The specific site selected for nest placement seemed to be more influential on nesting success. We now know more about the clutch size, hatching success, fidelity to nesting areas, and habitat selection of King Eiders. This information will be important for future efforts to develop population models.

Understanding migration routes and important habitat areas at sea was also needed, especially with expanded interest in oil and gas activities in offshore areas and a rapidly changing Arctic environment. Several approaches were used to collect the information. Collecting feather or toe nail samples from eiders could be analyzed for several stable isotopes. Because isotopes vary across the range of King Eiders, analysis of tissues could provide insights into molting and wintering areas. During molting, the newly grown feathers will reflect the stable isotope ratios found in that area. Additionally, attaching satellite transmitters to birds could directly provide information on their travel routes, molting sites, and wintering areas. Both techniques provided useful information. King Eiders spread out across the Bering Sea for molting and wintering. Migration routes and timing through the Bering Straits were documented, as were important staging areas, especially in the eastern Chukchi Sea. Below are several manuscripts highlighting some of this information.

Male Common Eider. Photo: Josh London

Male King Eider in flight. Photo: Kate Stafford

Male King Eider


Banner photo credit: Kate Stafford

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