Decline of the Steller’s Eider in Alaska

The Steller’s eider (Polysticta stelleri), one of four types of eider ducks, is a marine bird residing in arctic and sub-arctic regions. This sea duck spends most of its time in shallow coastal waters though will move inland, in cases over 200 miles, to breed. There are three breeding populations currently recognised – two in Russia (Atlantic and Pacific populations) and one in Alaska. The Alaskan breeding population is predominantly found on the Arctic Coastal Plain (northern Alaska) centered around Barrow though a very small sub-population of breeders is found in western Alaska on the Yukon-Kuskokwim (Y-K) Delta. It is estimated that there are over 150 000 birds in the Russia-Pacific population, some 30 000 to 50 000 in the Russia-Atlantic population, and around 10 000 in Alaska.

The Problem

• The Alaska-breeding population of the Steller’s eider was listed as threatened under the U.S. Endangered Species Act in 1997 after it became evident that the species had virtually disappeared from its breeding grounds in western Alaska. The species may have occurred in this region – primarily the Y-K Delta – in significant numbers though by the 1960s or 70s it had become extremely rare. Indeed, no nests were found between 1975 and 1993 and only seven nests were found between 1994 and 2002.
• In northern Alaska, meanwhile, it appears that the species’ range may have contracted over the past decades. However, historical (pre-1970) records are limited making it impossible to draw firm conclusions.
• Overall, longterm trends in numbers for both Alaskan sub-populations are poorly known given the limited information on past and current population sizes. Aerial surveys of the wintering population prior spring migration – which includes eiders from both the Russia-Pacific and Alaskan breeding populations – commenced in 1992 and show a substantial downward trend since then. However, the accuracy of the surveys is deemed questionable.

The Causes

• The cause(s) of the decline in numbers of Steller’s eiders nesting in Alaska and the contraction of its breeding range within the state are unknown. Hunting, loss of habitat, disturbance, or disease do not appear to be implicated.
• Potential factors in their decline may include:
• Lead poisoning: While lead poisoning from ingested gun pellets is thought to be an important cause of mortality for the spectacled eider, another threatened sea duck species breeding on the Y-K Delta, it is not known if the Steller’s eider has been similarly impacted. Non-toxic shot is now required in the U.S. but lead shot from past use has been found to settle very slowly in Y-K Delta sediments and is thus likely to be available for continued ingestion.
• Large-scale environmental change: Changes in the Bering Sea may have affected food availability and/or quality in the wintering and moulting areas.
• Increased predation: Steller’s eiders nest on the ground and, with the exception of camouflage, have little defense against nest predators such as foxes, jaegars, ravens, and gulls. It has been hypothesized that changes in predation pressure may have contributed to the near disappearance of the species from the Y-K Delta.
• Current threats to the Steller’s eider – whether natural or human-related – are also poorly understood and may include ingestion of spent lead shot, reductions in the quantity or quality of marine food, disease, collisions with fishing boats, human-related disturbance and loss or alteration of habitat in the developing Barrow region, and illegal or unintentional shooting. Increases in predation pressure resulting in nest failure may also be a problem and there is some concern that human activity – such as providing nesting structures for ravens or alternate food sources (e.g., garbage dumps) for predators such as foxes and gulls – may be disrupting normal predatory-prey dynamics. Exposure to contaminants, notably oil, is an ongoing threat as numbers of eiders wintering in southwest Alaska can be found in harbors and bays and near industrial activity, all areas with substantial maritime traffic.
• Any recovery of Alaska’s Steller’s eider will be difficult due to the poor understanding of the cause(s) of decline and current threats, and slow as the species in some areas does not nest every year. Research and management efforts continue to be challenging given the isolation of the breeding and wintering grounds. Indeed, the Steller’s Eider Recovery Program is focused almost entirely on identifying and quantifying risks to the speces.

The Context

• The fifteen species of sea ducks are considered the most poorly understood group of waterfowl in North America and even the most basic biological information is lacking for some species. For all of the North American sea ducks there is little reliable data on population sizes and trends or on annual productivity. In terms of the Steller’s eider, there is a considerable lack of information on habitat requirements, reproductive and survival rates, or the effects of disease and parasites.
• The decline of the Steller’s eider mirrors a wide range of changes in the Gulf of Alaska and Bering Sea region which has also seen declines in other sea ducks such as the spectacled eider and long-tailed duck, seabirds such as the pigeon guillemot and Kittlitz’s murrelet, and marine mammals including the sea otter, harbor and northern fur seals, and Steller’s sea lion. At the same time, temperatures have changed more in Alaska than anywhere else over the past three decades though it is currently unknown what the relative roles of human-induced global warming and natural climate cycles may be. Other factors are likely involved and may include, depending on the species and location, the Exxon Valdez oil spill, historical whaling, fisheries, and environmental pollutants.
• 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.
• In January of 2001 the U.S. Fish and Wildlife Service (USFWS) designated 2830 sq. miles of land and marine waters as Steller’s eider critical habitat – i.e., those areas considered essential to its conservation and which may require special management considerations. Included are breeding, moulting, wintering, and spring staging areas in northern, southwestern, and southcoastal Alaska. However, no critical habitat was designated on the North Slope (including the Barrow region) because, according to the USFWS, there was a lack of biological information on Steller’s eider habitat use and due to concerns that such a designation would undermine ongoing work with partners to carry out conservation efforts.

Further Reading

Flint, P.L et al.. 1997. Exposure of Spectacled Eiders and other diving ducks to lead in western Alaska. Canadian Journal of Zoology 75: 439-443.

Kertell, K. 1991. Disappearance of the Steller’s Eider from the Yukon-Kuskokwim Delta, Alaska. Arctic 44: 177-187.

Solovieva, D.V. et al. 1998. Polysticta stelleri Steller’s eider. Birds of the Western Palearctic Update 2(3): 145-158.

U.S. Fish and Wildlife Service. 2002. Steller’s Eider Recovery Plan. Fairbanks, Alaska.

Zydelis, R. et al.  2006.  Recent changes in the status of Steller's Eider Polysticta stelleri wintering in Europe: a decline or redistribution?  Bird Conservation International 16(3): 217-236.