Somateria mollissima


Taxonomy [top]

Kingdom Phylum Class Order Family

Scientific Name: Somateria mollissima
Species Authority: (Linnaeus, 1758)
Common Name(s):
English Common Eider, Eider

Assessment Information [top]

Red List Category & Criteria: Least Concern ver 3.1
Year Published: 2012
Date Assessed: 2012-05-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Pihl, S.
Facilitator/Compiler(s): Ekstrom, J., Butchart, S., Malpas, L., Calvert, R.
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.

Geographic Range [top]

Range Description: 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).

Austria; Belarus; Belgium; Bulgaria; Canada; Czech Republic; Denmark; Estonia; Faroe Islands; Finland; France; Germany; Greenland; Iceland; Ireland; Italy; Latvia; Liechtenstein; Lithuania; Macedonia, the former Yugoslav Republic of; Netherlands; Norway; Poland; Romania; Russian Federation; Saint Pierre and Miquelon; Slovakia; Slovenia; Spain; Svalbard and Jan Mayen; Sweden; Switzerland; Ukraine; United Kingdom; United States (Georgia - Vagrant)
Bosnia and Herzegovina; Croatia; Georgia; Greece; Hungary; Israel; Japan; Luxembourg; Montenegro; Portugal; Serbia (Serbia); Turkey
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: 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).
For further information about this species, see 22680405_somateria_mollissima.pdf.
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Population Trend: Unknown

Habitat and Ecology [top]

Habitat and 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).

Systems: Terrestrial; Marine

Threats [top]

Major Threat(s): 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)).

Citation: BirdLife International 2012. Somateria mollissima. The IUCN Red List of Threatened Species. Version 2015.2. <>. Downloaded on 03 September 2015.
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