Head and adjoined neck's part of Male Red-breasted Merganser in breeding plumage are black with green and purple metallic gloss; crest on head is formed by extended feathers. White neck is with black strip on rear part. Mantle and inner shoulders are black; rump and flanks have black and white fine scale pattern. Outer shoulders are black; much of lesser, median and greater wing coverts and secondaries are white. Craw and breast are buff-rusty brown mottled; breast-flanks near wing have some white feathers with quite broad black edges. White speculum divided on three parts by black strips. Tail is grayish-brown. Female's crown and upper-neck are rusty-brown; flanks are rusty white mottled; throat is white dark-rusty mottled. Upperparts and lesser and median wing coverts are dark-brown with grey edges; craw is white rusty and brownish mottled. Flanks are brownish with grayish edges; underparts are white. Speculum is formed by secondaries and its great coverts and divided on two parts by black strip formed by bases of secondaries. Male in summer and juveniles are similar on female. Legs are red or orange; yellow in juveniles; bill is orange with dark comb and tip. Eyes are red or orange; or yellow and brown in juveniles. Sizes: male wing 235 - 260 mm, female 210-235 mm; tail 77-90 mm, tarsus 40-50 mm, male bill 53-63 mm, female bill 48-58 mm.
Red-breasted Merganser breeds on Balkhash lake, Alakol lake, on lakes of Kokchetav uplands and in Southern Altai (middle part of Bukhtarma river, Markakol' lake). Widespread on migration, occasionally winters to the south of Turkestan, also on Irtysh river near Ermak and on Sorbulak lake where 3 birds recorded on 1 December 2002.
Rare breeding migrant. Inhabits fresh or salty fish lakes and rivers, both on plains and in mountains up to 1500 m in Altai region. Appears early – end of April in pairs and in small groups. Breeds in separate pairs not far apart, probably in loose colonies. Nest is built in holes between stones from dry grass; nest cup lined with plenty of down. Clutches of 9-12 eggs in early June; broods observed July – mid-August. Migration begins in October.
"Птицы Казахстана" том 1. АН КазССР. Алма-Ата, 1960. Gavrilov E. I., Gavrilov A. E. "The Birds of Kazakhstan". Almaty, 2005. Э.И.Гаврилов. "Фауна и распространение птиц Казахстана". Алматы, 1999.
