Justification of Red List Category
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). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very 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.
The global population is estimated to number c.800,000-900,000 individuals (Wetlands International 2015), 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). The European population is estimated at 37,500-45,500 pairs, which equates to 75,000-91,000 mature individuals (BirdLife International 2015).
The overall population trend is decreasing, although one population may be stable and another has unknown trends (Wetlands International 2015). In North America, the species has undergone a small, statistically insignificant increase, over the last 40 years (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. In Europe, the population trend is unknown (BirdLife International 2015).
The King Eider breeds along the Arctic coasts of Europe, North America and Asia. It can be found further south during the winter, including the north-east and north-west coast of North America, on Iceland and islands north of the United Kingdom, and on the Pacific coast of Asia to the tip of the Kamchatka Peninsula (Russia) (del Hoyo et al. 1992).
Behaviour This species is fully migratory (del Hoyo et al. 1992). It breeds from late-June onwards, usually in well-dispersed solitary pairs, although in some areas it may also form loose colonies (Madge and Burn 1988; del Hoyo et al. 1992; Kear 2005). Males gather in vast flocks between July and August and undertake moult migrations to favoured marine areas often more than a thousand miles from the breeding grounds (Snow and Perrins 1998; Johnsgard 1978). The autumn migration to winter quarters, by both males and females), peaks between August and October, with stragglers still leaving the breeding grounds during September (Snow and Perrins 1998). The timing of the return passage in the spring is determined by the ice conditions and the thawing of inland breeding waters (Snow and Perrins 1998). Non-breeding birds generally oversummer south of the breeding range or may remain on the wintering grounds (Madge and Burn 1988). The species is highly gregarious when not breeding, migrating in groups of up to c.1,000 individuals ( and aggregating into enormous flocks during the moulting period (e.g. 100,000 individuals off the western coast of Greenland)) and during the winter (Johnsgard 1978; Madge and Burn 1988; Snow and Perrins 1998).
Habitat Breeding The species breeds on dry Artic tundra near freshwater lakes, pools, bogs, marshes, streams and small rivers the coast or up to 50 km (rarely up to 100 km) inland (del Hoyo et al. 1992, Kear 2005; Madge and Burn 1988). It shows a preference for shallow fresh waters with emergent vegetation for initial brood rearing, afterwards moving to more saline waters where the young fledge (Snow and Perrins 1998, Kear 2005). Non-breeding The species generally moults in sheltered fjords and bays with high densities of benthic fauna (Kear 2005), and winters at sea on deep offshore waters close to the edge of sea ice or in coastal areas with shallow waters (del Hoyo et al. 1992, Kear 2005).
Diet Its diet consists predominantly of animal matter such as benthic molluscs, crustaceans, larval insects (del Hoyo et al. 1992) (e.g. caddisflies and midges), echinoderms (e.g. sea urchins and sand dollars) and other marine invertebrates, although the seeds and the vegetative parts of tundra plants, sedges and aquatic plants may also be taken on the breeding grounds, and algae, eelgrass Zostera spp. and Ruppia maritima may be taken at sea (Johnsgard 1978; del Hoyo et al. 1992).
Breeding site The nest is a slight hollow on dry ground and is usually positioned near water, in the open, or under the cover of driftwood, grass hummocks or rocks (Flint et al. 1984; del Hoyo et al. 1992).
Levels of hunting in this species are poorly regulated in parts of the range and may be unsustainable in some areas. Two to five percent of the population has been harvested annually in Alaska and Canada in recent years (Powell et al. 2012), accounting for 16,000 individuals (Rothe et al. 2015). Harvesting levels can reach 6.9% in the Northwest Territories (Byers and Dickson 2001), while in south west Greenland there has been an estimate of between 10-20% of the winter population killed annually (Hansen 2002). No data is available for Russia. In one study covering the wintering population in southwest Greenland, 22% of adults carried embedded lead shots (Falk et al. 2006). Lethal and sub-lethal levels of lead have also been detected in related Spectacled Eiders Somateria fischeri in Alaska where they are thought to be reducing survival rates (Grand et al. 1998, Flint et al. 2016). Given their overlapping ranges and similar ecologies, King Eiders are likely to be affected in a similar way.The species is also vulnerable to mortality from bycatch, with 100-200 individuals killed per year around Nuuk, Greenland. Bycatch of all eider species has been reported in Newfoundland, Iceland, Norway, Germany and the Baltic Sea (Merkel 2004). Oil spills poses an additional threat, a small spill in the Pribilof Islands in 1997 caused high Eider mortality. Should an oil spill occur in the eastern Chukchi Sea, a primary staging area for King Eiders during autumn and spring migrations, it would be expected to cause a population decline of between 2.1-3.4% a year in northern Alaska (Bentzen and Powell 2012). Oil fields have been developed in areas where King Eider nests in northern Alaska, but no decline in numbers has been documented (Powell et al. 2012), with pollution from spills being a greater threat than the disturbance of oil exploration activities and development of platforms. Climate change poses an ongoing and future threat to the species through ocean acidification and habitat shifting. Decreased pH values of seawater may lead to declines in molluscs which are key prey items in eider diets (Steinacher et al. 2009, USFWS 2010, Carboneras and Kirwan 2017). Remote sensing has shown shrinkage and disappearance of lakes and ponds in Alaska and Siberia (Smith et al. 2005, Riordan et al. 2006) which could constitute breeding habitat loss. However, no link between wetland loss and population decline has been demonstrated. Climate change is still predicted to cause dramatic habitat changes in the sensitive Arctic region (Fox et al. 2015), likely to alter the population dynamics of this high arctic species.
Conservation Actions Underway
Bern Convention Appendix II. CMS Appendix II. There are currently no known conservation measures for this species within its European range.
Conservation Actions Proposed
Strict legislation on oil exploration and transportation is needed as well as protection of key sites. Research into the species's ecology and population dynamics will help future conservation measures.
Text account compilers
Martin, R., Palmer-Newton, A., Stuart, A., Arendarczyk, B., Butchart, S., Calvert, R., Ashpole, J, Ekstrom, J., Fjagesund, T., Hermes, C., Malpas, L.
BirdLife International (2019) Species factsheet: Somateria spectabilis. Downloaded from http://www.birdlife.org on 21/10/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 21/10/2019.