Habitat requirements. The Long-tailed Duck breeds in typical Arctic tundra environments, nesting close to shallow wetlands (ponds, lakes and coastal bays) in low lying tundra, often on islands. Some nest in loose colonies, sometimes in association with Arctic Tern Sterna paradisaea or Red-breasted Goose Branta ruficollis colonies, themselves typically associated with a raptor nest. They may also breed in tundra bogs, or along rivers and at coastal sites in the high Arctic. It generally avoids wooded tundra, although in north Scandinavia it does breed in the arctic-alpine zone among willows and dwarf birch. In the southern Fennoscandian mountain range it is typically associated with deeper ponds and lakes. There is evidence that breeding Common Scoter (and other diving ducks) prefer lakes with a low density of Brown Trout Salmo trutta where there is less competition for the preferred prey of adults and ducklings (macro- invertebrates), and it is possible that Long-tailed Ducks may show similar preferences (Håland 2012, Håland in litt.). During moult, birds frequent coastal lagoons or large lakes, mostly relatively near to the breeding area, although some undertake more significant movements to reach safe moulting sites. In winter it selects offshore banks and relatively shallow marine areas, generally <25 m deep, however it is the only seaduck in the Baltic to occur in large numbers in waters deeper than 20 ▇. ▇▇▇▇ et al. (1995) and ▇▇▇▇ et al. (2011) found the main depth range of Long-tailed Ducks in the Baltic Sea to be 10–35 m. In spring more birds forage in more shallow areas of the Baltic Sea, typically diving 3-8 m. Dives to depths of 60 m have also been recorded (Schorger 1951). During winter Long-tailed Ducks forage mostly diurnally, primarily seeking molluscs, but also taking amphipods and fish, co-existing with other seaducks by taking smaller prey items. Smaller marine bivalves are particularly abundant in the Baltic Sea compared to other marine areas because their growth is restricted by the lower salinity levels. They also take other crustaceans, marine invertebrates (including echinoderms and worms) and fish eggs. Within the Baltic Sea Long-tailed Ducks feed on sandbanks as well as reefs. On reefs they prey on Blue Mussel Mytilus spp. and other epibenthic invertebrates. On sandbanks they dig for various small- sized solitary bivalves. In the eastern Baltic Sea, the large isopod Saduria entomon forms an additional food source locally (▇▇▇▇ & ▇▇▇▇ 1996). In general, whilst Blue Mussels are probably the main food for most overwintering Long-tailed Ducks in the Baltic Sea, they are less reliant on them than other seaducks, enabling them to also winter in less productive, soft-bottomed habitats (▇▇▇▇▇▇▇ 1972, Žydelis & Ruškyte 2005). A comparative study with ▇▇▇▇▇▇▇’▇ ▇▇▇▇▇ Polysticta stelleri in Varanger fjord, north Norway (Barents Sea) also showed greater flexibility, where Long-tailed Ducks changed their diet completely from feeding on benthic invertebrates in early winter, as do ▇▇▇▇▇▇▇’▇ Eiders, to spawning Capelin Mallotus villosus in late winter (Bustnes & Systad 2001).
Appears in 1 contract
Habitat requirements. The Long-tailed Duck breeds in typical Arctic tundra environments, nesting close to shallow wetlands (ponds, lakes and coastal bays) in low lying tundra, often on islands. Some nest in loose colonies, sometimes in association with Arctic Tern Sterna paradisaea or Red-breasted Goose Branta ruficollis colonies, themselves typically associated with a raptor nest. They may also breed in tundra bogs, or along rivers and at coastal sites in the high Arctic. It generally avoids wooded tundra, although in north Scandinavia it does breed in the arctic-alpine zone among willows and dwarf birch. In the southern Fennoscandian mountain range it is typically associated with deeper ponds and lakes. There is evidence that breeding Common Scoter (and other diving ducks) prefer lakes with a low density of Brown Trout Salmo trutta where there is less competition for the preferred prey of adults and ducklings (macro- macro-invertebrates), and it is possible that Long-tailed Ducks may show similar preferences (Håland 2012, Håland in litt.). During moult, birds frequent coastal lagoons or large lakes, mostly relatively near to the breeding area, although some undertake more significant movements to reach safe moulting sites. In winter it selects offshore banks and relatively shallow marine areas, generally <25 m deep, however it is the only seaduck in the Baltic to occur in large numbers in waters deeper than 20 ▇. ▇▇▇▇ et al. (1995) and ▇▇▇▇ et al. (2011) found the main depth range of Long-tailed Ducks in the Baltic Sea to be 10–35 m. In spring more birds forage in more shallow areas of the Baltic Sea, typically diving 3-8 m. Dives to depths of 60 m have also been recorded (Schorger 1951). During winter Long-tailed Ducks forage mostly diurnally, primarily seeking molluscs, but also taking amphipods and fish, co-existing with other seaducks by taking smaller prey items. Smaller marine bivalves are particularly abundant in the Baltic Sea compared to other marine areas because their growth is restricted by the lower salinity levels. They also take other crustaceans, marine invertebrates (including echinoderms and worms) and fish eggs. Within the Baltic Sea Long-tailed Ducks feed on sandbanks as well as reefs. On reefs they prey on Blue Mussel Mytilus spp. and other epibenthic invertebrates. On sandbanks they dig for various small- small-sized solitary bivalves. In the eastern Baltic Sea, the large isopod Saduria entomon forms an additional food source locally (▇▇▇▇ & ▇▇▇▇ 1996). In general, whilst Blue Mussels are probably the main food for most overwintering Long-tailed Ducks in the Baltic Sea, they are less reliant on them than other seaducks, enabling them to also winter in less productive, soft-bottomed habitats (▇▇▇▇▇▇▇ 1972, Žydelis & Ruškyte 2005). A comparative study with ▇▇▇▇▇▇▇’▇ ▇▇▇▇▇ Polysticta stelleri in Varanger fjord, north Norway (Barents Sea) also showed greater flexibility, where Long-tailed Ducks changed their diet completely from feeding on benthic invertebrates in early winter, as do ▇▇▇▇▇▇▇’▇ Eiders, to spawning Capelin Mallotus villosus in late winter (Bustnes & Systad 2001).
Appears in 1 contract