State Museum of Natural History
Biodiversity Data Centre

Somateria mollissima (Linnaeus, 1758)

  • Anas mollissima Linnaeus, 1758
Vernacular Name
Common Eider, Eider, Eider Duck
Conservation status
IUCN: NT; Be (III); Bo (AEWA); EUBD (IIA); RDBUkr: Вразливі
Value of species
The species 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 (U.S.A.), the western Mediterranean and the southern tip of the Kamchatka Peninsula (Russia) (del Hoyo et al. 1992). There are four subspecies in North America: Pacific (S. mollissima v-nigra), American (S. m. dresseri), Hudson Bay (S. m. sedentaria), and Northern (S. m. borealis) (Bowman et al. 2015). The global population is estimated to number c. 3,300,000-4,000,000 individuals (Wetlands International 2012). The European population is estimated at 791,000-955,000 pairs, which equates to 1,580,000-1,910,000 mature individuals (BirdLife International 2015). Trend Justification: In Europe the population size is currently declining overall at a rate of >40% over three generations (27 years) (BirdLife International 2015). A decline has been evident since the late 1990s in the largest flyway population of S. m. mollissima in the Baltic and Wadden Seas, based both on breeding data (Ekroos et al. 2012) and on midwinter counts conducted as part of the International Waterbird Census (Nagy et al. 2014). Rapid declines have been reported for the islands of Gotland (from 7,140 nesting females in 2007 to 1,310 in 2015) and Öland in the Baltic Sea (K. Larsson in litt. 2015). Europe (including Greenland) holds >60% of the global population (Wetlands International 2012), so the declines in Europe are globally significant. The remainder of the population occurs in North America where population trends are variable. The Pacific population, S. m. v-nigra, which represents c. 4% of the global population is thought to have declined in the northern parts of its range between the 1980s and early 2000s and in central Arctic Canada and north-west Alaska it has declined but appears to be increasing in the rest of Alaska (Bowman et al. 2015). The American population, S. m. dresseri, (c. 9% global population) shows variable trends with the northern population increasing and southern population decreasing. Trends are uncertain for the Hudson Bay, S. m. sedentaria, (c. 6% global population) and Northern, S. m. borealis, (c. 16% global population) populations. Given the strong declines in the European population and a lack of compensatory increases in the North American population the overall population trend is thought to be declining moderately rapidly. 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 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). 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). The nest is a slight hollow in the ground that is usually positioned in the shelter of rocks or vegetation but may also be in the open (del Hoyo et al. 1992). 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). 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).
Book reference
  • Котенко Т.И., Ардамацкая Т.Б., Дубина Д.В. и др. Биоразнообразие Джарылгача: современное состояние и пути сохранения // Вісник зоології. – 2000. – Спец. випуск. – 240 с.
  • Проект організації території Чорноморського біосферного заповідника НАН України та охорони його природних комплексів. Ч. 1. К.- 2016. 300 с.

Taxonomic branch