Nesting season wrap up: A summary of the U.S. Fish and Wildlife Service's eider project near Barrow

November 19th 12:08 am | David Safine - USFWS    

This past summer marked the 21st consecutive year of the eider research project near Barrow, Alaska. The research project began in 1991 as a collaborative effort between the U.S. Fish and Wildlife Service and the North Slope Borough Department of Wildlife Management. This project was developed to collect information on the breeding biology of Steller's eiders nesting near Barrow as at that time very little was known about this species.

The tundra near Barrow provides nesting and brood rearing habitat for the two species of sea ducks in Alaska that are listed as threatened under the Endangered Species Act: Alaska-breeding Steller's and spectacled eiders. Spectacled eiders nest across the North Slope and on the Yukon-Kuskokwim Delta, whereas Steller's eiders only appear to nest with any regularity in the Barrow Triangle on the northern tip of the North Slope, between Admiralty Bay and the Chukchi Sea. We are concerned about Steller's eiders because of their limited breeding range in North America, and their small population size (less than 1,000 birds).

Steller's eiders are a unique sea duck in that their nesting effort and success is highly variable over time. Some years, a relatively large number of Steller's eiders arrive along the road system near Barrow, and if conditions on the tundra are suitable, many pairs remain in the Barrow area to nest and raise young. In other years, few Steller's eiders are observed and either none or only a small number stay and nest. In general, the years with more Steller's eiders and more nests tend to be the same years with higher numbers of brown lemmings, pomarine jaegers, and snowy owls. So each year of the project is a surprise, as we never know what the eiders will be up to until the snow melts and the birds arrive in early June. In 2009, very few Steller's eiders arrived, and no nests were found. In 2010, more Steller's eiders arrived in Barrow and two nests were located, and this summer we counted over a hundred eiders and located 27 nests.

The eider project is focused on learning about Steller's and spectacled eiders, but it also collects information on the other species of sea ducks, geese, and swans nesting near Barrow to provide a perspective on the entire ecosystem. The primary goals of the project are to collect information on the number of eiders that arrive in Barrow each spring, the number and success of eiders that nest, and the success of female that raise broods. Because the study area near Barrow is quite large (over 70 square miles), we rely on a team of people to accomplish our goals. In recent years this team has consisted of U.S. Fish and Wildlife Service biologists, technicians, and volunteers, and Barrow High School students hired through the Eider Journey Program.

The project begins with a survey of the study area (areas within approximately 3 miles of the road system network near Barrow). The observers count all Steller's and spectacled eiders and predatory birds (gulls, jaegers, owls, and ravens) seen. The survey takes 10-14 days to complete; this year it was conducted from June 12th - 21st. In the entire survey area we counted over 60 male (110 total) Steller's and over 125 male (200 total) spectacled eiders. For Steller's eiders, 2011 was a year of moderate abundance near Barrow, not as high as peak years (e.g., 1999 and 2008 with over 110 males counted), but by no means a low year (e.g., 2002 and 2009 when less than 10 males were counted). This summer also had moderate numbers of pomarine jaegers and snowy owls. Lemming numbers were higher this year than the last two years, but they were not as abundant as the "peak" levels seen in 2008.

The next phase of the project involves searching for eider nests and monitoring the nests we find. We found 27 Steller's and 22 spectacled eider nests. For Steller's eiders, 21 of the 27 nests were found active (attended by a female and containing viable eggs), and 14 of those hatched. For spectacled eiders, 16 of the 22 nests were found active, and 12 hatched. Nest failure for both eider species in 2011 was primarily due to predation by birds (mainly jaegers, and to a lesser extent owls and gulls). Nest success was relatively high for sea ducks near Barrow; better than observations from the last two summers near Barrow.

The final phase of the project is to monitor the survival and habitat use of eider broods. To accomplish this goal, we attach small (9 gram) external radio-transmitters to adult female eiders just before their nests hatch. These transmitters are designed to be temporary, and are typically shed 2-6 months after attachment. Once nests hatch, we are able to relocate the female and her brood using radio telemetry. We track females and ducklings until they are either capable of flight or the brood is lost. For Steller's eiders, 8 of the 9 broods we monitored with radio-transmitters fledged ducklings (meaning the ducklings survived 36 days after hatching and were able to fly). Apparent survival rates for duckling in 2011 are the highest we have seen for Steller's eiders since we began monitoring ducklings in 1995. For spectacled eiders, at least 2 of the 8 broods we monitored fledged ducklings (more spectacled eider broods likely fledged, but their longer distance movements made locating some broods later in the season difficult). This was the first year we monitored the survival of spectacled eider ducklings.

This project would not be possible without the continued support of agencies, partners, and staff. We would like to extend our gratitude to the following agencies: North Slope Borough School District and Department of Wildlife Management, Barrow Arctic Science Consortium, Native Village of Barrow, Inupiat Community of the Arctic Slope, Ukpeagvik Inupiat Corporation, National Fish and Wildlife Foundation, U. S. Bureau of Land Management, and ConocoPhillips Alaska Inc. We are also very appreciative of the efforts of our volunteers, who donate their time each year toward eider conservation. Lastly, we would like to thank our hard working crew of Eider Journey students: Miriam Diaz, Johnathan Nelson, Stephanie Nelson, Agnes Okakok, and Elmer Thompson Jr.

 

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