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= Steller's eider (Polysticta stelleri) =

The Steller’s eider is a small sea duck known to live in marine habitats along the coast of Alaska and Russia. This duck is the only known species within the Polysticta genus and presents with sexually dimorphic traits. Steller’s eiders range from 43 to 47 centimeters in height and have an average mass between 852 and 877 grams. Their diet mainly consists of invertebrates in near-shore marine habitats. The International Union for Conservation of Nature (IUCN) classifies this species as vulnerable, but under the Endangered Species Act (ESA), only the Alaska-breeding population of this species is listed as threatened. The Alaska-breeding population was originally listed in 1997 due to a decrease in range and population caused by habitat destruction, disease or predation, and inadequate regulation. This species does not have a robust history of habitat conservation but current major threats to the Steller’s eider include chronic petroleum spills, increased risk of lead poisoning, collisions with man-made structures, random events, and the Allee effect.

Taxonomy
Polysticta stelleri is a small sea duck that lives in Arctic Russia and Alaska. The common name for this species is Steller’s eider. There are three breeding populations known as Russian-Arctic, Russian-Pacific, and Alaskan. This marine duck is of the genus Polysticta in the family Anatidae and order Anseriformes. There are many different sea ducks in the order of Anseriformes, but Steller’s eider is currently the only known member of the Polysticta genus. The Steller’s eider species is classified as vulnerable under the IUCN.

Diet
Steller’s eiders generally forage by diving up to 9 meters underwater by bill dipping and body tipping. These sea ducks primarily consume near-shore invertebrates in the fall and winter. These sea ducks are considered generalists in foraging and diet, consuming what invertebrates and fauna are available. Steller’s eider have been found to consume crustaceans, Polychaetes, fauna associated with eelgrass beds, and certain bivalves such as blue mussel and baltic clam.

Physical Characteristics
The Steller’s eider ranges in height from 43 and 47 centimeters and have an average mass between 852 and 877 grams. These ducks have a squarish head and angular bill. Steller’s eiders have sexually dimorphic plumage. Males usually present with a blackish throat and collar and white secondary tail feathers. In addition, males have a white to silver head with a black spot surrounding each eye and an additional black spot in front of each wing. Males also have chestnut colored chests and an olive patch at the nape of the neck. Young females have mottled brown plumage until they acquire breeding plumage in the fall of their second year, prior to breeding. Mature females present with red-brown coloring and blue flight feathers, whitish inner webs, and pale eye rings.

Behavior
In 2016, US Fish and Wildlife Service (USFWS) biologists from the Fairbanks Fish and Wildlife Field Office completed a thorough Species Status Assessment (SSA) of the Steller’s eider. This includes detailed information about their life history and reproduction, which is summarized below. This section of the SSA was significantly informed by materials published by Lori Quakenbush.

Steller’s eider birds mainly live in marine environments and only occupy terrestrial habitats during nesting season. They begin breeding between 2 to 3 years of age. The Alaska-breeding birds find their nesting grounds in late May and begin to nest in mid June, depending on snowmelt. New birds hatch in late July, about a month after nest initiation, and fledging occurs a month after this.

Sex proportion and breeding success determine when the birds leave their breeding grounds. Males typically leave the breeding grounds in small flocks shortly after the females begin to incubate, around late June. In the two months following this, female location and dispersal depends on breeding success. Flocks with more females presumably had failed breeders, and these females will leave the breeding grounds earlier with the males. In flocks with successful reproduction, females remain at their nesting sites until early September.

After leaving their breeding grounds, the Alaska-breeding population migrates to southwest Alaska where the birds experience a flightless molt for about a month, beginning with the young adults. For the remaining adults, the timing of their molt corresponds to when they arrived at the molting site. Typically the males arrive first in late August after leaving the breeding grounds. Soon after the females will arrive who failed to breed, and eventually the successful females arrive with their broods. Steller’s eiders prefer molting sites that are shallow and contain eelgrass beds, intertidal mud flats, and sand flats.

Following their molt, the Steller’s eiders widely disperse throughout the area. However, many birds may remain at the molting sites unless they are forced to disperse due to freezing conditions. In late winter, they begin to form pairs and undergo courtship which they complete before leaving for the breeding grounds again.

Historical and Current Geographic Range
There are three recognized breeding populations of Steller’s eider: two in arctic Russia and one in Alaska. Only the Alaska-breeding population is listed under the ESA. There is uncertainty surrounding the historical range of the Alaska-breeding population, but scientists speculate it may have occurred from the eastern Aleutian Islands to the western and northern Alaskan coasts in a sporadic distribution.

Currently, the Alaska-breeding Steller’s eiders mainly breed on the western Arctic Coastal Plain (ACP) in northern Alaska. They also breed to a very limited extent on the Yukon-Kuskokwim (Y-K) Delta. This limited breeding on the Y-K Delta raises concerns as it was historically a regular breeding area for the species. After breeding on land, they commonly molt in shallow marine waters along the southwest Alaska Peninsula near Izembek Lagoon, Nelson Lagoon, Herendeen Bay, and Port Moller. Following this molting stage, these ducks distribute throughout a wider range of southern coastal Alaska, returning to the northwest to breed again in the late spring and early summer.

Historical and Current Population Status
There is extremely limited data about the historical population numbers for the Steller’s eider. The majority of these older estimates are based on scattered observations. Currently, scientists mainly rely on extensive aerial surveys to form breeding population estimations. Based on these surveys, USFWS officials have found that breeding population size varies considerably from year to year. This has made it difficult to determine any significant population trends and detect accurate population sizes. However, they have tentatively concluded that hundreds or thousands of Steller’s eiders live on the North Slope of Alaska. Surveys from the Y-K Delta have not detected any Steller’s eiders. Based on this information in comparison with historical information, scientists are confident that the species’ abundance has decreased on the Y-K Delta. Additionally, even in areas where Steller’s eiders persist, both their frequency of occurrence and breeding have decreased in recent decades.

Critical Habitat
When a species is listed under the ESA, a critical habitat must be assigned to it. By definition, the critical habitat for a species must include spaces where there are physical and biological features essential to its conservation which may require special protection. In 2001, USFWS released the final critical habitat for the Alaska-breeding population of the Steller’s eider. It consists of one terrestrial and four marine areas including the Y-K Delta, Kuskokwim Shoals, Seal Islands, Nelson Lagoon, and Izembek Lagoon. This consists of roughly 7,333 square kilometers and 1,363 kilometers of shoreline.

ESA Listing History
In 1991, scientists first petitioned to list the Steller’s eider bird species as “Endangered” under the ESA. In 1994, the USFWS found that the entire species did not qualify for listing, but the Alaska-breeding population formed a Distinct Population Segment based on a previous definition in old USFWS policy. This distinction led to the listing of the Steller’s eider Alaska-breeding population as “Threatened” in 1997. The main reason for listing was a substantial decrease in the population’s breeding range, leading to the increased vulnerability of its remaining breeding members. The major threats noted in this listing include habitat destruction, disease or predation, and inadequate regulation.

Since its original listing, a critical habitat was designated in 2001 and a recovery plan was published in 2002. Despite its listing in 1997, a five year review was not initiated until 2016. To conduct this review and determine if the listing status should be changed, biologists in Fairbanks, Alaska conducted the SSA which was reviewed by the Eider Recovery Team and scientific experts. Using information gathered in the SSA, biologists concluded in 2019 that the listing status should not change, and the Alaska-breeding population of Steller’s eider remains “Threatened” today.

Major Threats
The major threats to the Alaska-breeding population are a considerable decrease in the species’ nesting range and a general reduction in the number of Steller’s eiders nesting in Alaska. This decrease in nesting leaves future Alaska-breeding populations vulnerable to extinction. While originally unclear, scientists have speculated that reasons for range and population reduction include habitat loss, hunting, predation, lead poisoning, and ecosystem change. Due to the wide geographic range and migratory pattern of this species, it has been difficult to fully understand how threats have altered population levels over time. New threats include chronic petroleum spills, increased risk of lead poisoning, collisions with man-made structures, random events, and the Allee effect.

Human Impacts
Human actions that could further threaten the Alaska-breeding population of Steller’s eider include gas-oil development, village expansion, marine transport, commercial fishing, and environmental pollution. These actions could immediately degrade or infringe upon the current habitat, leading to lasting effects on habitat quality. This is cause for significant concern, as Steller’s eiders already suffer from range contraction, and these human impacts could worsen that problem.

Projects that could potentially affect the threatened breeding population are closely regulated in order to protect this species. Examples include The Integrated Activity Plan for the National Petroleum Reserve-Alaska in 2013 and the Akutan Airport Project in 2011. These projects, and others like them, have continuously updated legislation to monitor their potential threat level to Steller’s eiders. USFWS Biological Opinion has reviewed these projects and deemed that their impacts are not significant. This means the amount of potential habitat disturbance and displacement, collisions with structures, and the threat of oil and toxic substance spills is monitored for minimal habitat disturbance and maintained foraging efficiency.

Over time, a major human-caused threat to Steller’s eiders has been the presence of lead in much of their foraging areas. Both lethal and non lethal doses of lead have affected the Alaska-breeding population. The presence of lead shot is relatively common in tundra wetlands and nearshore marine waters where foraging takes place, especially in the Arctic Coastal Plain near villages. The state of Alaska prohibits the use of lead shot for hunting waterfowl. In addition, there have been collaborative efforts to reduce the overall presence of lead shot, mainly prohibiting lead shot for hunting all birds on the North Slope of Alaska. The use of lead shot has been greatly reduced due to these regulations.

Conservation Efforts and Issues
The original recovery plan for the Steller’s eider was published in 2002. This document includes an extensive list of tasks and sub-tasks to conserve the Alaska-breeding population. The main tasks included: reduce exposure to lead, reduce nest predation, reduce hunting and shooting mortality, elucidate distribution and abundance, acquire information on marine ecology and breeding ecology, acquire demographic information needed for population modeling efforts, maintain or re-establish subpopulation on YK-Delta, and develop partnerships for recovery efforts. These tasks were determined based on the original cause of the population’s listing: contraction of range. The cause of this contraction was poorly understood, so the original recovery plan focused on simultaneously conserving the current population by mitigating previously known threats and better understanding why the range was decreasing.

The most recent recovery document was released in 2017 and includes an extensive task lisk for continued conservation of the Steller’s eider. These new tasks are sorted based on level of priority. Unfortunately this list was published with no accompanying information to explain the reasoning behind these tasks. Additionally, there was no update as to how the original recovery plan affected Steller’s eider conservation in the 15 years between recovery evaluations.

However, in their 2019 SSA, scientists from the Fairbanks Fish and Wildlife Field Office described two major conservation issues for the Steller’s eider Alaska-breeding population. First, they mention that scientists have struggled to properly monitor and conserve this species because it spans political boundaries. The threatened birds move between Alaska and Russia, and this national separation causes problems in aligning conservation efforts. The Russian populations have consistently higher numbers, so it would help to work with Russia to improve the bird's population levels in Alaska.

Second, global climate change will continue to pose threats to the Alaska-breeding population because of habitat alteration. Scientists are uncertain how changes to the tundra and marine environments will change existing populations, but predict that population resilience will decrease. Combined with the other major threats, climate change has the potential to become a very serious threat to the Alaska-breeding population. If management increases and other current threats are handled properly, the Steller’s eider will have a greater chance of adapting to climate change.