Somateria mollissima 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Aves Anseriformes Anatidae

Scientific Name: Somateria mollissima (Linnaeus, 1758)
Regional Assessments:
Common Name(s):
English Common Eider, Eider
Spanish Eider común
Taxonomic Source(s): Cramp, S. and Simmons, K.E.L. (eds). 1977-1994. Handbook of the birds of Europe, the Middle East and Africa. The birds of the western Palearctic. Oxford University Press, Oxford.
Identification information: 50-71 cm. Breeding male very distinctive with black coronal region, divided by white streak over central crown to nape (Carboneras et al. 2014). Rest of head white with pale green patches on nape and rear-ear coverts. Upperparts white, breast rosy-pink, rump, tail and rest of underparts black. Bill olive-grey with pale yellow tip. Female warm brown with black bars. Juveniles resemble female. Voice Characteristic cooing call between autumn and spring, otherwise generally silent.

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2016
Date Assessed: 2016-10-01
Assessor(s): BirdLife International
Reviewer(s): Butchart, S. & Symes, A.
Contributor(s): Laursen, K., Coulson, J., Drysdale, A., Gudmundsson, G., Larsson, K., Meltofte, H., Petersen, I., Pihl, S. & Waltho, C.
Facilitator/Compiler(s): Ashpole, J, Burfield, I., Butchart, S., Calvert, R., Ekstrom, J., Ieronymidou, C., Malpas, L., Moreno, R., Pople, R., Wheatley, H., Wright, L
This species has been uplisted to Near Threatened. Within Europe it has experienced moderate declines and these have not been compensated for by increases elsewhere in the species's range. Declines are thought to be driven by a range of threats including overharvesting of aquatic resources, pollution, disturbance and hunting. Should the declines be found to be more severe, or new information reveal declines in the S. m. sedentaria and S. m. borealis populations then the species would warrant uplisting; it almost meets the requirements for listing as threatened under criterion A4abcde.
Previously published Red List assessments:

Geographic Range [top]

Range Description:

The breeding range of this species is widely distributed around the mid- to high-latitude coasts of the northern hemisphere, particularly at the higher latitudes. It has a Holarctic distribution, being present in both Eurasia and North America. However, its distribution is not continuous across the Holarctic. There are distinct and persistent gaps in both the central parts of the Russian Arctic and the Canadian Arctic. The distributional gap in Russia (54° longitude) is considerably wider than that in Canada (6° longitude). These gaps can be attributed to the presence of ice all year round, especially landfast sea ice, at these locations. At the highest latitudes, the presence of breeding birds is largely limited by the distribution of ice-free conditions during June.

In winter, the range is more compressed, with migratory northern populations largely wintering within the range of the southerly sedentary populations (Waltho and Coulson 2015). The southern limits of regular wintering ranges are southern Alaska (USA) at 51°N, New Jersey (USA) at 41°N, W France at 44°N and Kuril Islands (Russia) at 50°N (Waltho and Coulson 2015).

Globally there are six widely recognised subspecies (Waltho and Coulson 2015, del Hoyo et al. 1992), with four in Eurasia, European (S. mollissima mollissima), Faroes (S. m. faeroeensis), Northern (S. m. borealis) and Pacific (S. mollissima v-nigrum), and 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).

Countries occurrence:
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 (Central Asian Russia - Vagrant, Eastern Asian Russia, European Russia); Saint Pierre and Miquelon; Slovakia; Slovenia; Spain; Svalbard and Jan Mayen; Sweden; Switzerland; Ukraine; United Kingdom; United States
Bosnia and Herzegovina; Croatia; Georgia; Greece; Hungary; Israel; Japan; Luxembourg; Montenegro; Portugal; Serbia; Turkey
Additional data:
Continuing decline in area of occupancy (AOO):Unknown
Extreme fluctuations in area of occupancy (AOO):NoEstimated extent of occurrence (EOO) - km2:59900000
Continuing decline in extent of occurrence (EOO):UnknownExtreme fluctuations in extent of occurrence (EOO):No
Continuing decline in number of locations:Unknown
Extreme fluctuations in the number of locations:No
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population: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.
Current Population Trend:Unknown
Additional data:
Continuing decline of mature individuals:Unknown
Extreme fluctuations:NoPopulation severely fragmented:No
Continuing decline in subpopulations:Unknown
Extreme fluctuations in subpopulations:NoAll individuals in one subpopulation:No

Habitat and Ecology [top]

Habitat and Ecology:

The Common Eider always nest on the ground and usually in areas free of mammalian predators (Waltho and Coulson 2015), including coastal 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), coastal lakes and rivers (Johnsgard 1978, Kear 2005) or on tundra pools close to the coast (del Hoyo et al. 1992). They use a wide range of nesting habitats, including bare ground, shingle, grassland, scrub, under trees and in derelict buildings (Waltho and Coulson 2015). 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). Large nesting aggregations form where safe nesting sites are at a premium (Waltho and Coulson 2015).

These species typically moults on shallow marine or sheltered coastal waters free from disturbance (Kear 2005, Waltho and Coulson 2015). It winters on shallow coasts (usually <10m depth), bays and estuaries (Waltho and Coulson 2015, del Hoyo et al. 1992), especially where there are high abundances of benthic molluscs, especially Mytilus edulis (Waltho and Coulson 2015,Camphuysen et al. 2002, Ens 2006). It may also occur inland on freshwater lakes when on passage and during the winter (rarely) (Waltho and Coulson 2015). Its diet consists predominantly of benthic molluscs  especially Mytilus edulis, although a wide range of crustaceans (e.g. amphipods and isopods), echinoderms, other marine invertebrates and fish may also be taken (Waltho and Coulson 2015, del Hoyo et al. 1992, Johnsgard 1978). During the breeding season incubating females in the Arctic  are reported to feed on  algae, berries and the seeds and leaves of surrounding tundra plants (del Hoyo et al. 1992), while in temperate regions they do not eat leading to temporary breakdown of their digestive system (Waltho and Coulson 2015, Laursen and Møller 2016), Northern populations of this species are migratory (>1000km) but southern populations are largely sedentary (Waltho and Coulson 2015). Migratory nature is largely a response to coastal sea ice (Waltho and Coulson 2015). 

Systems:Terrestrial; Marine
Continuing decline in area, extent and/or quality of habitat:Unknown
Generation Length (years):9
Movement patterns:Full Migrant
Congregatory:Congregatory (and dispersive)

Threats [top]

Major Threat(s):

The species is vulnerable to chronic coastal oil pollution  and to  major oil spills especially in areas where large moulting and wintering concentrations occur (Waltho and Coulson 2015, del Hoyo et al. 1992, Kear 2005, Nikolaeva et al. 2006). It also comes into conflict with the shellfish aquaculture industry where it can cause serious losses to line-farmed mussel, and where harvesting of mussel beds can deplete 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 other recreational activities such as boat tours [Burnham et al. 2012] as well as scientific research [Bolduc and Guillemette 2003]) increases the likelihood of predation on young (Keller 1991). The critical factor for the well-being of the species is usually the very low survival rate of the young ducklings (Waltho and Coulson 2015).

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)).It is hunted unsustainably in Russia (Nikolaeva et al. 2006) in Denmark (Bregnballe et al. 2006) and Greenland (Merkel 2004). 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]). Increased and additive levels of predation on the nesting grounds, including by White-tailed Eagle Haliaeetus albicilla may be responsible for recent increases in female mortality in some areas (Ekroos et al. 2012). Avian cholera represents a new threat, capable of wiping out colonies of this species (Descamps et al. 2012, Tjørnløv et al. 2013) and Wellfleet Bay Virus has led to heavy mortality in Massachusetts (USA) (Ballard et al. 2012) . The species may also be sensitive to the effects of climate change (Carboneras et al. 2012). Mussel quality, and subsequent eider breeding condition, appears to be sensitive to nutrient content of coastal waters (Laursen and Møller 2014), declining with nutrient levels.

Conservation Actions [top]

Conservation Actions: Conservation and Research Actions Underway
EU Birds Directive Annex II and III. CMS Appendix II. Changes to hunting regulations in Greenland in 2001 shortened the length of the hunting season which is thought to have led to a rapid increase in population size (Burnham et al. 2012). However the hunting regulations have recently changed and the effect on the population is not yet known. Restrictions were also introduced in Denmark in 2004/2005 and 2011/2012 with the aim of reducing the proportion of female birds killed and increasing the population growth rate (Christensen and Hounisen 2014).

Conservation and Research Actions Proposed
Sustainable levels of hunting should be established in those areas where the species is harvested and legislation established and enforced to ensure this. Conduct flyway-scale winter counts (Ekroos et al. 2012) and ensure monitoring is coordinated across the species's range (I. K. Petersen in litt. 2015). Key areas should be protected from all forms of disturbance as well as oil exploration, drilling and transportation. Further research needed into impacts of declining nutrient levels in coastal waters affecting mussel populations, site carrying capacity, body condition and subsequent breeding productivity, across the species range. Levels of shellfish harvesting should be monitored to ensure sustainability and measures to minimise bycatch in fishing nets promoted amongst fisheries. International monitoring plans should be developed and a programme of research put in place, while taking precautions to minimise the impact of scientific work.

Citation: BirdLife International. 2016. Somateria mollissima. The IUCN Red List of Threatened Species 2016: e.T22680405A92861620. . Downloaded on 26 September 2018.
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