(805) Locustella certhiola.
Motacilla certhiola Pall., Zoogr. Rosso-Asiat., i, p. 309 (1811) (Lake Baikal). Locustella certhiola. Blanf. & Oates, i; p. 352.
Vernacular names. Sun-batta-sorai (Assamese).
Description. Forehead and anterior crown olive-brown; crown and nape reddish brown; the latter often almost white, boldly streaked with black, back, scapulars and lesser wing-coverts reddish brown with broad central streaks of black, sometimes wanting on the hind neck in very old birds ; greater coverts and innermost secondaries black with narrow whitish fringes; quills grey-brown edged paler; lower back and rump reddish brown, almost, or quite, unmarked; upper tail-coverts reddish brown with broad black centres; tail reddish brown, suffused with black on the terminal half, with black shaft-stripes and cross-rayed, the outermost feathers almost entirely black except for broad white tips; supercilium white or pale buffy-white ; lores brown with a white line below to the eye; ear-coverts brown with white shafts; sides of neck rufous-brown; below white or buffy-white, the flanks and sometimes the breast suffused with reddish brown; under tail coverts bright buff.
Colours of soft parts. Iris brown or hazel-brown; upper mandible dark horny-brown, lower mandible fleshy-yellow or ochraceous" (Everitt); legs and feet white to pale fleshy.
Measurements. Length about 130 mm.; wing 62 to 68 mm.; tail 58 to 63 mm.; tarsus about 20 mm.; culmen 11.5 to 12.5 mm.
The Nestling is like the male above but more profusely marked with black on the rump and lower back; below it is a bright yellow-buff, the sides of the throat, neck and breast boldly streaked with black and the sides of the head and flanks brownish; the under tail-coverts are pale rufous-brown : the supercilium is bright yellow-buff.
In the Autumn the nestling moults into a stage halfway between the adult and nestling plumage, retaining the buff lower plumage but losing most of the streaks.
The Summer plumage is a little brighter above than in Winter and is a clearer white below.
Distribution. Pallas's Grasshopper-Warbler breeds in Eastern Siberia as far West as the Yenesei. In Winter it is found throughout South China, Burma, Assam and Bengal, straggling thence into Central and South-Central India as far as Orissa.
Nidification. Breeds in damp grassy meadows, generally placing its nest low down in the grass growing on small hummocks. The nest is deep cup-shaped and made of grasses lined with grass-stems. The eggs are said to number four to six in a full clutch and are of two types—pale rose-pink dotted with reddish brown over the whole surface or deep lilac or rose-pink with a few tiny specks of brownish black and minutely freckled all over with, reddish, A few eggs also have one or two hair-lines at the larger end. Sixteen eggs average 18.8 x 13.7 mm., and in general appearance are very like deep-coloured eggs of some of our Indian Triburas. The birds lay in late June to July.
Habits. Seebohm remarks that he " found it a very shy, skulking bird, frequenting the marshes and swampy copses on the great meadows by the river side." In the beginning of the breeding-season the male sings constantly, every now and then rising into the air, fluttering stationary for a few seconds and then dropping down again into cover.
Both this bird and the Streaked Grasshopper-Warbler were very common in Assam and E. Bengal in Winter, frequenting the rice fields as well as reeds and water-plants in swamps. At this time of year they have, of course, no song but utter an occasional note sounding like chir-chirrr.