The genus Acrocephalus contains five Indian species which are common in winter. Three of them appear to remain in suitable localities and in limited numbers throughout the summer and to breed in India. The majority of these birds, however, leave in spring and doubtless go to Central and Northern Asia.
The Reed-Warblers are birds of plain plumage closely allied to each other, and not easy to be identified except by comparison of size or by the structure of the wing. They haunt reed-beds, canals, ditches, and almost any locality which is fairly well watered. They are great skulkers and are seldom seen, but the harsh note that they all have generally betrays their presence. In the breeding-season they all have a pleasing song.
The winter and summer plumages do not vary greatly, the chief difference being an intensity of rufous or fulvous in the winter after the autumn moult. These birds appear to undergo a complete moult in the spring. The sexes are alike.
In the birds of this genus the bill is of considerable Length, being nearly as long as the head; there are three large rictal bristles on each side of the head, and the forehead is smooth. The first primary is very minute, and the second reaches nearly to the tip of the wing. The tail is fairly long and greatly rounded, and the feathers are rather narrow and pointed *.
Key to the Species.
a. Of large size ; wing about 3.
a1. Second primary shorter than the fifth. A. stentoreus, p. 356. b1. Second primary equal to, or longer than the fourth…………………. A. orientalis, p. 357.
b. Of small size ; wing under 2.5.
e1. With a distinct black stripe over the yellow supercilium………………….A. bistrigiceps, p. 358.
d1. With no black stripe over the super¬cilium.
a2. Bill from gape to tip measuring under .7.
a3. Second primary between the sixth and seventh in Length; upper plumage olivaceous …………………. A. dumetorum, p. 359.
b3. Second primary between the seventh and eighth or equal to eighth; upper plumage rufous. A. agricola, p. 359.
b2. Bill from gape to tip fully .8………………….A. macrorhynchus, p. 360.
* The following species of Reed-Warblers are likely to occur within our limits, but are not yet known to do so: - ACROCEPHALUS ARUNDINACEUS (Linn.), which occurs in Afghanistan and Yarkand.
A. Schoenobaenus (Linn.), which occurs as far east as Fao in the Persian gulf.
A. STREPERUS (Vieill.), which has occurred at Bampur, in Persian Afghanistan.
A. PALUSTRIS (Bechst.), which has occurred at Fao and in Persia.