The Spectacled Eider

The spectacled eider (Somateria fischeri), one of four species of eider ducks, is a large-bodied sea duck easily recognized by its goggle-like eye patches. The eiders - which include the spectacled, Steller's, king, and common - are marine diving birds of Arctic and northern coasts.

There are three distinct breeding populations of spectacled eiders worldwide: in the Yukon-Kuskowim (Y-K) Delta and North Slope regions of Alaska; and along the north coast of Siberia in Russia. The vast majority of breeding pairs - over 90% - nest in Russia. It appears that most, if not all, spectacled eiders overwinter together in pack ice openings (polynyas) in a small area between St. Lawrence and St. Matthew Islands in the central Bering Sea. Counts of these large and dense overwintering flocks conservatively place the worldwide population size at around 375 000 individuals.

The Problem

• Spectacled eider numbers on the Y-K Delta (western Alaska) have fallen precipitously - by some 96% between the mid-1970s and the early 1990s, from an estimated 48 000 nesting pairs to less than 2500 pairs. Recent surveys suggest that nesting numbers have increased slightly over the last decade to approximately 3500-4000 pairs.
• The North Slope (northern Alaska) breeding population is estimated at some 4745 pairs and is suspected to have declined slightly during the 1990s.
• While waterfowl as a group have been well-studied the sea ducks have not been an important management priority. Consequently, relatively little is known about their ecology and life history, or of the significance of the threats facing them. Spectacled eiders, in particular, are difficult to study. Most of their time is spent at sea, far from shore, and during nesting they are widely scattered across almost inaccessible arctic and subarctic tundra.
• As virtually all of the world's spectacled eiders overwinter in an area of ocean approximately 30 miles in diameter, they would appear to be particularly vulnerable to any environmental change in this region.

The Causes

• The cause(s) of the dramatic decline in spectacled eiders on the Y-K Delta, according to the US Fish and Wildlife Service (USFWS), are not likely to be understood. Nonetheless, there are ongoing concerns:
  • Lead poisoning: Studies have shown that lead poisoning - from ingested gun pellets - is a serious problem for at least some areas of the Y-K Delta. Lead has been diagnosed as the cause of death in some birds, and concentrations in blood from living birds has been found at levels that suggest that survival rates are being affected. While the use of non-toxic shot is now required in the U.S., studies in parts of the Y-K Delta show that lead shot used in the past settles very slowly into sediments and, therefore, is likely to remain available for continued ingestion for many years. It is currently not known if lead poisoning is a problem for spectacled eiders on the North Slope.
  • Subsistence hunting: While not considered a cause in the Y-K Delta decline, local hunting may be hindering or preventing recovery. Currently, an estimated 4% of breeding adults are shot and killed in this region each year. There are no estimates on numbers taken from the breeding population on the North Slope.
  • Changes in food supply: Sampling programs over the past decade suggest that spectacled eider food resources on the ocean wintering grounds are in decline. The benthic community has shifted from larger to smaller species of clams, and overall biomass of clams has fallen. It is currently not known if these changes are having - or will have - an impact on overall spectacled eider numbers.

The Context

• Due to its rapid and steep decline on the Y-K Delta, the spectacled eider was listed as threatened under the U.S. Endangered Species Act in 1993. In early 2001 the USFWS designated approximately 39 000 square miles of land and marine waters as critical habitat for the species which prohibits "destructive or adverse modification" of the designated regions by any activity funded, authorized, or carried out by a Federal agency. However, this designation has been controversial as it did not include areas originally proposed for the North Slope, such as in and around the Arctic National Wildlife Refuge. Critics have charged that these areas were omitted because of their potential to interfere with future oil and gas drilling while the USFWS has contended that a lack of biological information prevented a confident critical habitat assessment at the time of designation.
• Populations of other sea duck species have also fallen. According to the Sea Duck Joint Venture, a consortium of Canadian and U.S. government agencies, scientists, and native and conservation organizations, ten of the fifteen types of sea ducks found in North America have recently experienced decreases in overall numbers, some substantially so. One additional North American sea duck species, the Labrador duck, was driven to extinction by the 1880s.
• The decline in spectacled eiders are just one of many marine wildlife disturbances that have taken place in the Alaska region since the early 1970s. There have been significant declines of other sea ducks - the Steller's eider, common eider and longtailed duck - and in a variety of marine mammal and seabird populations. Complex changes in food availability - likely due to some combination of a natural climate regime shift and the effects of commercial fisheries - is considered to be the most important factor in most cases.

Further Reading

Web site of the Sea Duck Joint Venture: http://seaduckjv.org/index.html.

Balogh, G.  1999.  Lead and the spectacled eider. Endangered Species Bulletin 24(1): 6-7.

Bump, J.K. and Lovvorn, J.R.  2004.  Effects of lead structure in Bering Sea pack ice on the flight costs of wintering spectacled eiders.  Journal of Marine Systems 50(3-4): 113-139.

Petersen, M.R. and Douglas, D.C.  2004.  Winter ecology of Spectacled Eiders: Environmental characteristics and population change.  Condor 106(1): 79-94.

U.S. Fish and Wildlife Service.  2001. Final determination of critical habitat for the spectacled eider. Federal Register 66(25) / February 6: 9146-9185.