This species is strongly migratory. The species breeds on large, deep freshwater lakes in coniferous forest or on open tundra (Billerman et al. 2020). Some individuals remain in Iceland year-round, although most winter on sea coasts or on larger lakes across the North East Atlantic coast from Finland and Norway to Portugal and in the western Mediterranean. During the winter the species occurs singly, in pairs or in small loose flocks in marine habitats (Godfrey 1979, Snow and Perrins 1998). A pursuit diver, its diet consists predominantly of fish, including cod (Gadus morhua), haddock (Melanogrammus aeglefinus), herring (Clupea harengus), trout (Salmo), suckers (Catostomidae), minnows (Cyprinidae) and perch (Perca) as well as crustaceans, molluscs, aquatic insects, annelid worms, frogs, other amphibians and plant matter (e.g. Potamogeton spp., willow (Salix spp.) shoots, roots, seeds, moss and algae) (Billerman et al. 2020).

Although the generation length for both EU and Europe regional assessments were calculated using the same methodology, new information arriving after the EU assessments were undertaken gave rise to an update in the generation lengths. This new information was then used for the Europe level assessments giving rise to a difference between the generation lengths used for the EU and Europe regions.

The species breeds, in Greenland (to Denmark), and also notably in Iceland, with a small population also present in Svalbard and Jan Mayen (Norway). It winters on sea coasts or on larger lakes over a much wider area including the Atlantic coast of Europe from Finland to Portugal and the western Mediterranean (Billerman et al. 2020), but mainly in the United Kingdom, Ireland and Norway and also notably in Iceland.

Conservation Actions Underway
The species is listed under Appendix II of the Convention on Migratory Species and is listed under the African Eurasian Waterbird Agreement. It is listed in Article I under the EU Birds Directive. It occurs in 20 IBAs, including in Iceland, Norway (Svalbard and mainland Norway), Ireland, the United Kingdom and in Spain. It is a listed species in 83 Special Protection Areas in the EU Natura 2000 network.

Conservation Actions Proposed
Protect Important Bird Areas across range states and identify and designate additional important sites. Identify sites and areas where high gillnet bycatch is occurring, and develop effective mitigation solutions. Manage coastal and inland developments surrounding important breeding areas. Develop rapid and trans-boundary response plans to coastal oil spills.