A small diving duck (length 37-60 cm including tail, weight 550-900 g, wingspan 73-79 cm). Sexually dimorphic with complex seasonal variations. All-dark wings. Males unmistakable. In winter mostly white with blackish ear-coverts and grey face-sides, elongated white scapulars, black bill with broad pinkish band, grey feet and orange eye. In summer darker, with dark brown head, grey face-sides and female-like brown back. Sides are white. Males have
elongated tail feathers (up to 10-15 cm) all year. Females in winter are brown above, with white face and black ear-coverts, brown scapulars, grey bill and brown eyes. In summer darker, especially on face. Juveniles resemble females.
Key habitats - seasonality
Breeds on marshy grass tundra in the high Arctic, especially near small tundra lakes, pools, bogs and rivers. It also breeds on small rocky islands and larger offshore islands along Arctic coasts. Generally avoids wooded tundra, but breeds among willows and dwarf birch in the Scandinavian arctic-alpine zone (Snow & Perrins 1998, Carboneras & Kirvan 2015). Winters mostly at sea, generally far offshore in waters 10-35 m deep, but also in brackish lagoons or estuaries. Very rarely inland in large, deep freshwater lakes (BirdLife International 2012, Carboneras & Kirvan 2015).
Biology – migration, life strategy, feeding, trophic relation, etc.
A long distance migrant, moving in large flocks at night (including overland e.g. from White Sea to Gulf of Finland). However, it is very tolerant of cold winters and may overwinter far to the north if sea ice conditions allow (Carboneras & Kirvan 2015). The West Siberia/North Europe population moves predominantly to the south and west, with the vast majority breeding in western Russia and overwintering in the Baltic Sea. Small numbers also overwinter in the Barents Sea, close to the Kola Peninsula. Scandinavian birds are thought more likely to move west to the North Sea and North Atlantic (mostly along the coast of Norway). Concentrations of moulting birds, mostly males, form at a number of Arctic locations, including three key sites in the Pechora Sea (Hearn et al. in prep.).
In Norway spring migration takes place between April and early June (Båtvik 1994).
Long-term or seasonally monogamous. Sexually mature when 2 years old. Pair-bonds are established in winter or early spring. Breeding starts in June, as soon as the breeding sites are available. Breeds in single pairs or loose groups, often in association with Arctic Terns ore Red-breasted Geese. The nest is a natural depression on the ground, lined with plant matter and down, always close to water. Clutch is usually 6-9 greenish eggs, incubation takes 24-29 days (by female only) (Carboneras & Kirvan 2015).
Feeds almost exclusively by diving, usually on crustaceans, molluscs and other marine invertebrates. In freshwater also insects and plants. Typically dives to greater depths than other seaducks, regularly 3–10 m (50–60 m). In winter, flocks form huge rafts on sea, diving synchronously (Carboneras & Kirvan 2015).
Population status – numbers and trends
The global population is estimated to number c.6,200,000-6,800,000 individuals (Delany & Scott 2006). However, both total population size and historical population trends are uncertain. Krivenko & Vinogradov (2008) estimate a breeding population of 2,000,000 individuals in European Russia (Hearn et al. in prep.). Other European countries hold smaller populations: 10,000-30,000 pairs in Greenland (Boertmann 2008), 2000–3000 pairs in Iceland (Guðmundsson 1998), 500-1000 pairs in Svalbard (BirdLife International 2015), 900-1800 pairs in Sweden (Ottosson et al. 2012), 3000-7000 pairs in Norway (Shimmings & Øien 2015) and 1500-2000 pairs in Finland (Valkama et al. 2011).
The breeding population of Iceland and Greenland is assumed to be stable, but the population of W Siberia and N Europe is decreasing. Surveys of the wintering population in the Baltic sea indicate that the species has declined, from c. 4,272,000 individuals in 1992-1993 to c. 1,486,000 individuals in 2007-2009, a decline of c. 65% over a period of 16 years (Skov et al. 2011, BirdLife International 2012). The estimation of a real and severe decline is supported by data from the Gulf of Finland flyway, where the numbers observed on migration have fallen dramatically since the early 1990s at least (BirdLife International 2015). Norwegian winter count data indicate a -59% decline between 1980 and 2011. Along the west coast of Norway the number of wintering birds has decreased by c.70-80% in the same period. In Russia, around 2,000 birds are thought to overwinter off the Kola Peninsula. This is approximately 50% of what was found during surveys in the early 1990s (Hearn et al. in prep.).
Threats – natural and anthropogenic
Long-tailed Ducks are exposed to threats both on their breeding grounds and in their wintering sites. The reasons for the dramatic decline of the Baltic Sea winter population are not yet understood, but various pressures are identified that may have contributed to the observed declines. The species is experiencing low reproductive success on its Arctic breeding grounds. The results of autumn migration monitoring at various Baltic sites show that juveniles now represent a very low proportion of the population, indicating that insufficient young are being raised to compensate for adult mortality (Hearn et al. in prep.). Factors contributing to low productivity may include habitat degradation, wetland drainage, peat-extraction and changing ecological conditions, as well as increased predation on the breeding grounds, due to climate change, lack of distinctive 3-4 year rodent cycles and potential carry-over effects from threats in non-breeding areas (BirdLife International 2012, Hearn et al. in prep.).
The major anthropogenic threats away from the breeding grounds include small scale oil discharges, accidental bycatch in static fishing nets, hunting during migration, and development of wind farms and other offshore infrastructure (Hearn et al. in prep.). Additional threats include large scale accidental oil spills, competition from invasive fish species (e.g. Round Goby), disturbance from shipping activities and dredging/dumping of sediments and aggregates in coastal areas (Hearn et al. in prep.). The species has previously suffered heavy losses from an outbreak of avian cholera and is susceptible to avian influenza. Both diseases may be a threat in the future (BirdLife International 2012).
Conservation measures and needs
An international single species action plan for the Long-tailed Duck is prepared by the AEWA - Agreement on the Conservation of African-Eurasian Migratory Waterbirds. The action plan is expected to be formally adopted in November 2015 (AEWA 2015).
The long-term goal of the plan is to restore the populations of the Long-tailed Duck to a favourable conservation status within the agreement area and to remove the species from the threatened categories of the IUCN Red List (Hearn et al. in prep.).
IUCN - EN, Ru - EN (Murmansk - EN, Archangelsk - EN), Fi - EN