Arctic Loon

Black-throated Diver in breeding plumage has ashy-grey upper-head and neck; mantle is black with purple and green tinge and with rows of white spots; throat and upper part of fore-neck are black with green and purple tinges; there is row of white spots on throat; and white strips on neck-flanks; flanks are black; upperparts including axillaries are white. Bill is black; legs are black in outer parts and bluish-grey in inner ones. Eyes are red-brownish. In winter plumage upperparts are black-brownish; underparts including cheeks and feathers of neck are white; upperhead and rear-neck are grey. Juveniles have plumage as on winter adults, but more dingy. Sizes: wing 290-350 mm, tail 54-62 mm, tarsus 80-83 mm, bill 58-70 mm.

Black-throated Diver is rare breeding migrant. Spring occurrence end April – late May. Nesting on large reservoirs with surface vegetation in forest-steppe, steppe and on mountain taiga lakes. Breeds in separate pairs at 0.5-1.5 km from each other. Nest is built along the shores of lakes or on old floating vegetation in reservoirs from dry reed stems and leaves; sometimes eggs laid in shallow hole in wet ground. Clutches 2, rarely 3 eggs in mid-May - end of June. Incubation lasts 28 days. Often a brood consists of only one nestling. Juveniles recorded from end May to mid-September. Autumn migration singly and in flocks of up to 7 birds from second half of September before reservoirs freeze (generally to mid-October – early November).