Population trends of king and common eiders from spring migration counts at Point Barrow, Alaska between 1994 and 2016
Most king (Somateria spectabilis) and common eiders (S. mollissima v-nigra) breeding in the northwestern Nearctic migrate past Point Barrow, Alaska. Spring migration counts have been conducted there since 1953; during 1976–1996, both species declined > 50% for unknown reasons. To evaluate population trends, counts in 2003, 2004, 2015, and 2016 were compared to earlier counts. King eider estimates were 304,966 (95% CI ± 76,254) in 2003, 591,961 (± 172,011) in 2004, 796,419 (± 304,011) in 2015, and 322,381 (± 145,833) in 2016. Common eider estimates were 114,998 (± 28,566) in 2003, 110,561 (± 32,087) in 2004, 96,775 (± 39,913) in 2015, and 130,390 (± 34,548) in 2016. The 2016 estimate was likely biased low for king eiders due to weather (causing large pulses of king eiders to pass within 2 days) and early ice break-up (causing observers to count at greater distances from the flocks). Using all estimates, populations of both species were statistically stable during 1994–2016. Excluding the 2016 count for king eiders indicated a significant increase of 18.63%/year in that population. Photo analysis of flocks in 2016 indicated that observer counts averaged 4% lower, species detection was not different, but females’ counts were underestimated by 25%. Methods should be refined to reduce bias and variability. Ice-based spring counts are becoming more difficult due to earlier break-up, less stable ice, and new techniques or locations; or a switch to land-based summer/fall migration counts are needed. Population monitoring is needed to ensure sustainability of harvests for these valuable subsistence resources.
KeywordsBeaufort sea Arctic Population estimate Somateria spectabilis Somateria mollissima Chukchi sea
We thank the Bureau of Ocean Energy Management, Coastal Marine Institute (University of Alaska Fairbanks), Sea Duck Joint Venture, Wildlife Conservation Society, Wilburforce Foundation, Trust for Mutual Understanding, and North Slope Borough Department of Wildlife Management (NSB-DWM) for funding this study. Tim Bowman of the U.S. Fish and Wildlife Service provided substantial help in raising funds and took the photos in 2016. This study would not have been possible without the substantial personnel and logistical support, and advice, of the NSB-DWM; in particular, we would like to thank Taqulik Hepa, Craig George, Leslie Peirce, Dave Ramey, Benny Akootchook, and Bobby Sarren. We thank our many observers, Mike Knoche, Sally Andersen, Michael Wald, Rosemary McGuire, Vera Kokhanova, Brittany King, Ian Fife, Rita Frantz, Peter Detwiler, Kayla Sheimreif, Mark Dodds, Laura Phillips, Garnet Raven, Craig George, Cyd Hanns, Leslie Pierce, Forrest Kagak, Brian Person, Mike Bradbury, Melinda Dorin, Lynne Dickson, Bonnie Rogers, Josh London, Rick Raymond (BOEM), and our bear guard, Perry Anashugak for their hard work in the field and apologize if we have inadvertently left someone off the list. We thank Graham Frye for statistical advice and Tasha DiMArzio for counting thousands of eiders in pictures. We thank Richard Raymond, Timothy White, Phillip Martin and David Safine for their helpful comments on drafts of this manuscript. Any use of trade, firm, or product names is for descriptive purposes only and does not imply endorsement by the U.S. Government.
This study was funded by Sea Duck Joint Venture (Grant No. 110047), Trust for Mutual Understanding (Grant No. 110694), Coastal Marine Institute (Grant No. 110443), and Wilburforce (Grant No. 111064).
Compliance with ethical standards
Conflict of interest
There are no conflicts of interest to disclose.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. As no animals were handled, approached, or interfered with, we did not conduct an official IACUC.
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