(803) Acrocephalus concinens stevensi.
The Plains Paddy-field Warbler.
Acrocephalus concinens stevensi Stuart Baker, Bull. B. O C., xliii,. p. 16 (1922) (Hessamara, N. Lakhimpur, Assam).
Vernacular names. None recorded.
Description. A very much darker bird than either A. c. concinens or A. c. haringtoni. The brightest Winter plumage is as dark as the darkest breeding-plumage of either of these races. Both stevensi and haringtoni seem to have a rather broader first primary than true concinens.
Colours of soft parts. "Iris olive-brown; bill, upper mandible horny-black, paler on edge of commissure, lower mandible horny,, darker at tip; tarsus fleshy-brown." (H. Stevens.)
Measurements. Wing 49 to 53 mm.; tail 46 to 50 mm.; tarsus about 20 mm.; culmen 11 to 12 mm.; " culmen from true base-15 mm." (H. Stevens.)
The second primary is equal to the ninth or tenth, and the first primary measures about 11 mm.
Distribution. This Reed-Warbler, which was discovered breeding by Mr. and Mrs. H. Stevens in Lakhimpur appears to be a resident Plains-breeding form of concinens. Godwin-Austen obtained three breeding-specimens in May on the churs close to Lakhimpur in early May which agree exactly with Mr. Stevens's specimens. Many Pegu specimens appear referable to this race, and birds obtained by myself in Cachar and Sylhet were also the same.
Nidification. It is probable that the Plains Paddy-field "Warbler breeds wherever it is found from Assam to Lower Burma. Stevens describes the nest as a very neat, deep little cup of grass and shreds of reed-leaves, very well finished off and lined with still finer grasses. It is placed two or three feet from the ground in grass-covered plains and sand-banks and is fastened to three or four stems of the growing grass.
The full clutch of eggs numbers three, possibly four on rare occasions. They differ in colour from the mountain-breeding races much as do the eggs of Mrs. Stevens's plains-breeding Reed-Warbler from the Indian Great Reed-Warbler. In colour they are very brown-looking eggs with a light sienna ground boldly and heavily blotched with brown and pale olive-brown. Fifteen eggs average 16.1 x 12.0 mm.: maxima 17.2 X 12.0 arid 15.0 x 12.2 mm.; minima 15.9 X 12.1 and 15.8 x11.8 mm. The birds breed in April and May.
Habits. According to Mr. Stevens this is a bird of the dry grasslands, though it frequents those which are close to rivers and swamps.