Race:
Gavia arctica arctica Linnaeus, 1758

Synonyms

Colymbus arcticus L.
Urinator arcticus L.
Gavia arctica sushkini Zarudny, 1912

Description

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.

Biology

Black-throated Diver is rare breeding migrant. In spring it occurs from end of April to late May. Nests on large reservoirs with floating 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 on the shores or on old floating vegetation; nest is from dry reed stems and leaves; sometimes eggs were laid in shallow hole on wet ground. Clutches 2, rarely 3, eggs founded from middle of May to end of June. Incubation goes on 28 days. Often brood consists one nestling only. Juveniles recorded from end May to middle of September. Black-throated Divers in autumn migration fly out singly and in flocks of up to 7 birds. Autumn migration continues from second half of September until the time when open water freezes over (mostly up to middle of October - early November).

References

"Птицы Казахстана" том 1. "Наука". Алма-Ата, 1960.
Э.И.Гаврилов. "Фауна и распространение птиц Казахстана". Алматы, 1999.
Gavrilov E. I., Gavrilov A. E. "The Birds of Kazakhstan". Almaty, 2005