The species breeds on Arctic dwarf heath (Snow and Perrins 1998, Kear 2005) or boggy tundra on pools, small lakes, streams (Carboneras and Kirwan 2017) and slow-flowing rivers (Snow and Perrins 1998). It shows a preference for freshwater habitats (Carboneras and Kirwan 2017) with low banks (Flint et al. 1984), small islets (Kear 2005) and high abundances of aquatic invertebrate and plant life positioned in swampy valleys or among mossy bogs (Flint et al. 1984), especially where suitable shrubs (e.g. willow or birch) and herbaceous vegetation are available for nesting cover (Johnsgard 1978, Snow and Perrins 1998, Kear 2005). Although the species may use freshwater lakes on migration the majority moult and overwinter at sea on shallow inshore waters less than 20 m deep with abundant benthic fauna (Kear 2005), generally between 500 m and c.2 km from the shore (Snow and Perrins 1998). It arrives on its breeding grounds between late-April and May and breeds from late-May onwards (Madge and Burn 1988) in highly dispersed (Kear 2005) solitary pairs. The nest is a scrape on the ground hidden amongst vegetation (Carboneras and Kirwan 2017) close to water or placed further away in dwarf heath (Kear 2005). Its diet consists predominantly of molluscs, especially during the winter, although it occasionally takes other aquatic invertebrates such as crustaceans, worms (Carboneras and Kirwan 2017), echinoderms, isopods, amphipods (Kear 2005) and insects as well as small fish (Carboneras and Kirwan 2017) and fish eggs (Snow and Perrins 1998). On the breeding grounds the species may also consume plant matter such as seeds, roots and tubers (Carboneras and Kirwan 2017) and the vegetative parts of aquatic plants (Flint et al. 1984). This species is strongly migratory (Carboneras and Kirwan 2017).

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.

In Europe, the species breeds primarily in the European part of Russia and Sweden, with small numbers in Finland, Iceland and Norway.

Conservation Actions Underway
EU Birds Directive Annex II and III. CMS Appendix II. Current measures for the protection of this species are not sufficient and the species suffers from a lack of knowledge and research interest (Kear 2005). In the U.K. the species is listed as Red on the national Red List and is a U.K. Priority Species and Biodiversity Action Plan species. It is also listed as Endangered on the Red List of Baltic Wintering Birds (HELCOM 2013). Research and monitoring has been initiated by several organisations to identify the driving factors behind its decline and better understand the species's movements (WWT 2013).

Conservation Actions Proposed
Management actions at non-breeding sites are essential to maintain the health of this species. Measures should be taken to minimise bycatch in fisheries, regulate shipping traffic, implement and enforce hunting regulations (Bellebaum et al. 2012, HELCOM 2013), prevent accidental and chronic oil pollution and preserve feeding grounds (HELCOM 2013). Research and monitoring should continue, particularly into the effects of climate change on the species and its prey (Bellebaum et al. 2012).