Blyth's Reed Warbler

Acrocephalus dumetorum (Blyth, 1849)

		adult juvenile
2011-08-09 Ust-Kamenogorsk, Ablaketka, 2008-09-24 Almaty, Republic Square	© Vladimir Shefer © Askar Isabekov

Description

The Blyth's Reed Warbler is a medium-sized warbler (less than Sparrow); without dark mottles and streaks. The upperparts are plain olive-brown, sometimes with buffy or rusty tinge, especially expressed on rump. It is distinguished from the Marsh Warbler by the "colder" grey or olive coloring; light supercilium extends over the eye, is more expressed than light eye ring; light edges of the flight feathers are slightly marked. From the Eurasian Reed Warbler it is distinguished by same features and by absence of buffy tinge on the flanks. From Paddyfield Warbler it is distinguished by the slimmer constitution; by absence of rusty color on rump; by narrower, dimmer and shorter supercilium. The legs may be as dark (grey, brownish) and light (buffy, buffy-brownish). The seasonal differences of plumage are insignificant, after the summer molting birds become "warmer", rustier, especially on the wings and rump. Sexes are similar. Juveniles are not sure distinguished from adults by the more rustier tone, especially on the wings ad rump. The contact characters: 1st primary is not longer or slightly longer (on 1-2 mm) than wing coverts; 2nd primary is shorter than 5th one; on folded wing the primaries projection is less than 15 mm; claw of rear finger is shorter than finger; bill length 88,8-10,0 mm. Weight 9-15 grams, length about 13, wing 5,9-6,7, wingspan 17-19 cm.

Distribution

The Blyth's Reed Warbler breeds in Southwest Altai and Kalbinskiy Altai; in Irtysh valley between Semipalatinsk and Ust-Kamenogorsk. And probably it nests in some places of Kazakh upland; on Kurgaldzhino lakes; Kokchetav upland; on Chagly lake; and on Ishim valley at Maryevka. It noticed as breeding bird to Naurzum Reserve. It lives in isolated coniferous forests of steppe zone, in Tobol valley and in middle current of Ural valley also, though there are not the acknowledgements from these areas. Nests probably in Dzhungarskiy Alatau at Topolevka settlement, where the singing males recorded in the beginning of July. As an exception it breeds in foothills of Zailiyskiy Alatau, where in Almaty area on July 13 1935 the not-flying nestling was obtained. On the migration it occurs throughout in Kazakhstan; it is numerous in the south and south-east parts, especially in autumn (August - September). It rare migrates in highlands of Zailiyskiy Alatau ridge (Bolshoye Almatinskoye lake), where observed 23 May 1974 and 28 May 1977.

Biology

The Blyth's Warbler is abundant breeding migrant, in places passage migrant only. It inhabits the bush thickets near the rivers, lakes and marshes, on the meadow and rarely in tall grass with some bushes, both on plain and in mountains up to 2000 m. On migration it visits various forests, bushes, gardens, groves, forest-belts, reed beds, lucerne fields and tall weeds thickets. In southern areas it appears in end April – early May; and in early – mid-May in northern ones and in mountains. The latest spring migrants recorded in early June. It breeds in separate pairs, at 25-100 m one from another. Nest is built in bush (willow, currant, raspberry, honeysuckle, birch, dog-rose) or in tall grass (nettle, willow-herb, blackberry, reed); from the dry grass, cobweb and vegetation fluff; and sometimes is lined with hair. Clutches of 3-6 (usually 5) eggs is in late May – mid-July. Both parents feed juveniles, which fledge at 11-12 days old, in end June – mid-August. Autumn migration begins in late July, majority of the birds migrate in August; latest migrants recorded in mid-October.

References

В.К.Рябицев. "Птицы Урала, Приуралья и Западной Сибири". Екатеринбург, Изд-во Уральского университета, 2000. Э.И.Гаврилов. "Фауна и распространение птиц Казахстана". Алматы, 1999. Gavrilov E. I., Gavrilov A. E. "The Birds of Kazakhstan". Almaty, 2005. А.Ф.Ковшарь "Певчие птицы". Алма-Ата, "Кайнар", 1983.