Species

Justification
This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km² combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend is not known, but the population is not believed to be decreasing sufficiently rapidly to approach the thresholds under the population trend criterion (>30% decline over ten years or three generations). The population size is extremely large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

Taxonomic source(s)
AERC TAC. 2003. AERC TAC Checklist of bird taxa occurring in Western Palearctic region, 15th Draft. Available at: http://www.aerc.eu/DOCS/Bird_taxa_of _the_WP15.xls.
AOU. 1998. Check-list of North American birds. American Ornithologists' Union, Washington, D.C.
Cramp, S.; Perrins, C. M. 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

Distribution and population
The Common Eider is distributed over the northern coasts of Europe, North America, eastern Siberia and southern Greenland. It breeds in the Arctic and northern temperate regions, but its range expands during winter to as far south as New Jersey, southern Alaska (USA), the western Mediterranean and the southern tip of the Kamchatka Peninsula (Russia) (del Hoyo et al. 1992).

Population justification
The global population is estimated to number c.3,100,000-3,800,000 individuals (Wetlands International 2006), while the population in Russia has been estimated at c.10,000-100,000 breeding pairs and c.1,000-10,000 wintering individuals (Brazil 2009).

Trend justification
The overall population trend is uncertain, as some populations are decreasing, while others are increasing, stable, or have unknown trends (Wetlands International 2006). This species has undergone a small or statistically insignificant increase over the last 40 years in North America (data from Breeding Bird Survey and/or Christmas Bird Count: Butcher and Niven 2007) Note, however, that these surveys cover less than 50% of the species's range in North America.

Ecology
Behaviour The majority of this species is migratory (Flint et al. 1984) (although it does not travel great distances) (Madge and Burn 1988, Snow and Perrins 1998), with some populations e.g. in Europe being largely sedentary (Scott and Rose 1996). The species breeds from early-April (although the most northerly populations may not breed until mid-June (Madge and Burn 1988)), and generally nests in colonies (del Hoyo et al. 1992) of up to or occasionally more than 3,000 pairs (Snow and Perrins 1998). The species may also nest within colonies of Arctic tern Sterna paradisaea (Snow and Perrins 1998). The males and immature non-breeders of some populations may make extensive moult migrations to favoured areas where they form large moulting flocks (Snow and Perrins 1998) while the females remain on the breeding grounds (Madge and Burn 1988, Snow and Perrins 1998). The species passes the winter (from October to March) at sea, congregating in flocks (Flint et al. 1984) that may be as large as many thousands of individuals (Snow and Perrins 1998, Kear 2005). Habitat Breeding The species breeds on offshore islands and islets (Kear 2005) along low-lying rocky coasts (del Hoyo et al. 1992), on coastal shores and spits, on islets in brackish and freshwater lagoons (Kear 2005), lakes and rivers (Johnsgard 1978) close to the sea (Kear 2005) or on tundra pools, rivers (del Hoyo et al. 1992) and lakes (Madge and Burn 1988) up to 5 or 6 km inland (Kear 2005). It shows a preference for boulder-strewn or grassy islands (Johnsgard 1978) with sheltered approaches (Snow and Perrins 1998) that are safe from nest predators, although in the high Arctic where such shelter is unavailable more open sites must be used (in which case the species often nests in closely packed groups for protection) (Snow and Perrins 1998). Non-breeding The species typically moults on shallow marine or sheltered coastal waters (Kear 2005), and winters on shallow seashores, bays and estuaries (del Hoyo et al. 1992), especially where there are high abundances of benthic molluscs (Camphuysen et al. 2002, Ens 2006). It may also occur inland on freshwater lakes when on passage and during the winter (rarely) (Madge and Burn 1988). Diet Its diet consists predominantly of benthic molluscs although crustaceans (del Hoyo et al. 1992) (e.g. amphipods and isopods (Johnsgard 1978)), echinoderms, other marine invertebrates and fish may also be taken (del Hoyo et al. 1992). During the breeding season incubating females frequently complement their diet with algae, berries and the seeds and leaves of surrounding tundra plants (del Hoyo et al. 1992). Breeding site The nest is a slight hollow in the ground that is usually positioned in the shelter of rocks or vegetation but may also in the open (del Hoyo et al. 1992). The species is a colonial nester, often nesting at densities of up to 250 pairs per hectare, and there may be over 3,000 nests in some colonies (Snow and Perrins 1998). The species may also nest in colonies of Arctic tern Sterna paradisaea for protection against predation (Snow and Perrins 1998). Management information A study carried out in Canada found that in order to prevent reductions in nesting success as a result of disturbing and displacing incubating adults (thus increasing the likelihood of nest predation) researchers and wildlife managers should visit eider colonies as late as possible in the incubation period and avoid visiting colonies associated with high densities of eider egg predators (Bolduc and Guillemette 2003).

Threats
The species is vulnerable to chronic coastal oil pollution (Nikolaeva et al. 2006), especially oil spills (del Hoyo et al. 1992, Kear 2005, Nikolaeva et al. 2006), in areas where large moulting and wintering concentrations occur (del Hoyo et al. 1992). It also comes into conflict with the shellfish aquaculture industry which depletes the species's food resources (Kear 2005, Ens 2006, Nikolaeva et al. 2006,) and has previously lead to mass starvation events due to the over-fishing of benthic molluscs (e.g. in the Dutch Wadden Sea) (Camphuysen et al. 2002, Ens 2006). On the breeding grounds disturbance from the development of mineral resources along the coast (Nikolaeva et al. 2006) and from local shore-based activities (e.g. angling, dog-walking (Keller 1991) and scientific research (Bolduc and Guillemette 2003)) increases the likelihood of predation on young (Keller 1991). Unregulated tourism and shipping also cause disturbance to the species on its wintering grounds (Nikolaeva et al. 2006). The species commonly becomes entangled and drowned in monofilament nets (Kear 2005) (e.g. gillnets (Merkel 2004)), and it is hunted unsustainably (Nikolaeva et al. 2006) (e.g. in Denmark (Bregnballe et al. 2006) and Greenland (Merkel 2004)). Utilisation Populations of this species in the high Arctic are subject to shooting, especially in spring, by indigenous peoples for food (Byers and Dickson 2001, Kear 2005). This subsistence hunting is likely to be sustainable at current levels (Byers and Dickson 2001). The species is also shot for sport in North America (this harvest may exceed sustainable levels in some areas (Kear 2005)).

Related state of the world's birds case studies

• Commercial shellfisheries can negatively impact migratory waterbirds
• Nearly half of all bird species are used directly by people

References
Johnsgard, P. A. 1978. Ducks, geese and swans of the World. University of Nebraska Press, Lincoln and London.

Flint, V. E.; Boehme, R. L.; Kostin, Y. V.; Kuznetsov, A. A. 1984. A field guide to birds of the USSR. Princeton University Press, Princeton, New Jersey.

Madge, S.; Burn, H. 1988. Wildfowl. Christopher Helm, London.

Keller, V. E. 1991. Effects of human disturbance on Eider ducklings Somateria mollissima in an estuarine habitat in Scotland. Biological Conservation 58: 213-228.

del Hoyo, J.; Elliot, A.; Sargatal, J. 1992. Handbook of the Birds of the World, vol. 1: Ostrich to Ducks. Lynx Edicions, Barcelona, Spain.

Scott, D. A.; Rose, P. M. 1996. Atlas of Anatidae populations in Africa and western Eurasia. Wetlands International, Wageningen, Netherlands.

Snow, D. W.; Perrins, C. M. 1998. The Birds of the Western Palearctic vol. 1: Non-Passerines. Oxford University Press, Oxford.

Kear, J. 2005. Ducks, geese and swans volume 2: species accounts (Cairina to Mergus). Oxford University Press, Oxford, U.K.

Byers, T.; Dickson, D .L. 2001. Spring migration and subsistence hunting of king and common eiders at Holman, Northwest Territories, 1996-98. Arctic 54(2): 122-134.

Bolduc, F.; Guillemette, M. 2003. Human disturbance and nesting success of Common Eiders: interaction between visitors and gulls. Biological Conservation 110: 77-83.

Bregnballe, T.; Noer, H.; Christensen, T. K.; Clausen, P.; Asferg, T.; Fox, A. D.; Delany, S. 2006. Sustainable hunting of migratory waterbirds: the Danish approach. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 854-860. The Stationary Office, Edinburgh, UK.

Ens, B. J. 2006. The conflict between shellfisheries and migratory waterbirds in the Dutch Wadden Sea. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 806-811. The Stationary Office, Edinburgh, UK.

Nikolaeva, N. G.; Spiridonov, V. A.; Krasnov, Y. V. 2006. Existing and proposed marine protected areas and their relevance for seabird conservation: a case study in the Barents Sea region. In: Boere, G.; Galbraith, C., Stroud, D. (ed.), Waterbirds around the world, pp. 743-749. The Stationary Office, Edinburgh, UK.

Camphuysen, C. J.; Berrevoets, C. M.; Cremers, H. J. W. M.; Dekinga, A.; Dekker, R.; Ens, B. J.; van der Have, T. M.; Kats, R. K. H.; Kuiken, T.; Leopold, M. F.; van der Meer, J.; Piersma, T. 2002. Mass mortality of common eiders (Somateria mollissima) in the Dutch Wadden Sea, winter 1999/2000: starvation in a commercially exploited wetland of international importance. Biological Conservation 106: 303-317.

Merkel, F. R. 2004. Impact of hunting and gillnet fishery on wintering eiders in Nuuk, southwest Greenland. Waterbirds 27(4): 469-479.

Further web sources of information
Detailed species account from Birds in Europe: population estimates, trends and conservation status (BirdLife International 2004)

Hear sounds for this species from xeno-canto, the community database of shared bird sounds from around the world.

View photos and videos, and hear sounds of this species from the Internet Bird Collection

Text account compilers
Butchart, S., Calvert, R., Ekstrom, J., Malpas, L.

Contributors
Pihl, S.

IUCN Red List evaluators
Butchart, S., Symes, A.

Recommended citation
BirdLife International (2013) Species factsheet: Somateria mollissima. Downloaded from http://www.birdlife.org on 23/05/2013. Recommended citation for factsheets for more than one species: BirdLife International (2013) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 23/05/2013.

This information is based upon, and updates, the information published in BirdLife International (2000) Threatened birds of the world. Barcelona and Cambridge, UK: Lynx Edicions and BirdLife International, BirdLife International (2004) Threatened birds of the world 2004 CD-ROM and BirdLife International (2008) Threatened birds of the world 2008 CD-ROM. These sources provide the information for species accounts for the birds on the IUCN Red List.

To provide new information to update this factsheet or to correct any errors, please email BirdLife

To contribute to discussions on the evaluation of the IUCN Red List status of Globally Threatened Birds, please visit BirdLife's Globally Threatened Bird Forums.

Additional resources for this species

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