The species breeds in tundra, moorland regions (Kear 2005) and wooded tundra (Scott and Rose 1996) in the high Arctic, occupying small, shallow (Carboneras and Kirwan 2014), freshwater lakes, pools and rivers (Kear 2005) with grassy shorelines and high densities of invertebrate life (Johnsgard 1978). It shows a preference for water less than 6 m deep (usually 2 m) for diving. The species winters on shallow coastal waters (Kear 2005) less than 10 m deep (Scott and Rose 1996) as well as sheltered bays, estuaries and brackish coastal lagoons. It is also found inland on large lakes (Carboneras and Kirwan 2014) and reservoirs during this season (Madge and Burn 1988). It breeds in the high Arctic from late-May or early-June (depending on the timing of the Arctic thaw) (Kear 2005) in single pairs or loose groups (Carboneras and Kirwan 2014), often with colonies of nesting gulls or terns (Kear 2005) although it is not itself a colonial species (Snow and Perrins 1998). The nest is a shallow depression on the ground close to water, either in thick vegetation (Carboneras and Kirwan 2014), in cracks in rocks, under woody shrubs or under perennial herbaceous vegetation less than 50 cm high (Iceland) (Johnsgard 1978). Clutch size is normally 8–11 eggs. The species is omnivorous. Its diet consisting predominantly of molluscs but also includes laver shells (Hydrobia), insects, aquatic insect larvae, crustaceans, worms, small fish, and the roots, seeds and vegetative parts of aquatic plants such as sedges and water weeds. This species is fully migratory (Carboneras and Kirwan 2014). The autumn migration begins after the moulting period in mid-August (Scott and Rose 1996), with males tending to remain much further north than females or immatures (Carboneras and Kirwan 2014) leading to some sexual segregation during the winter (Madge and Burn 1988).

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.

This species breeds across the northern limits of Europe, although its population is almost entirely concentrated in Russia, with small populations found in other northern European countries such as Iceland and Sweden.

It winters further south, reaching the Adriatic Sea, northern Black Sea and western Caspian Sea in Europe (Carboneras and Kirwan 2014). Countries with notable wintering populations include the Netherlands, Germany, Sweden, Ukraine and Denmark.

Conservation Actions Underway
CMS Appendix II. This species is listed on Annex II (and III) of the EU Birds Directive and can only be hunted in those ten Member States specifically mentioned in the Birds Directive: Belgium, Denmark, Germany, Greece, France, Ireland, Latvia, Netherlands, Romania and U.K.. There are management plans to reduce fishery activity at two sites in the Netherlands (Ijsselmeer and Waddenzee) and in Finland a large-scale eradication of Mink (Mustela vison) in the Quark as an EU LIFE project (Jensen 2009) began in 2001 (Anon. 2005).

Conservation Actions Proposed
Preservation of large areas of breeding habitat in northern Europe and its highly localised north-west European wintering grounds. Identify Important Bird Areas and protect habitats and sites. Implement stricter regulations on oil exploitation and transportation. Restrict hunting. Conduct further research on the effects of disturbance from hunting and the nomadic habits of the species outside the breeding season (Tucker and Heath 1994). Continue Mink eradication programme.