692. Petrophila solitaria.
The Eastern Blue Rock-Thrush.
Turdus solitarius, P.L. S. Muller, Syst, Nat,, Anhang, p. 142 (1770). Turdus manillensis, Gmel, Syst. Nat. i, p. 833 (1788). Petrocincla manillensis (Gm.), Blyth, Cat. p. 164; Horsf. & M. Cat, i, p. 188. Cyanocincla solitaria (Mull.), Hume & Dav. S. F. vi, p. 248 ; Hume, Cat. no. 351 bis; id. S. F. xi, p. 125. Monticola solitaria (Mull), Seebohm, Cat. B. M. v, p. 319.
Coloration. Male. The whole head, neck, breast, upper plumage and lesser wing-coverts bright blue, most of the feathers with small white tips and subterminal black spots; median, greater, and primary coverts blackish, edged with blue and tipped with white ; quills and tail black, edged with bluish and each feather very narrowly tipped white; abdomen, vent, under tail-covert, axillaries, and under wing-coverts chestnut, with narrow white fringes and black subterminal bars; thighs and flank-feathers adjacent to them blue.
At the end of winter the white fringes and subterminal black bars on the blue parts of the plumage are entirely lost, and the marks on the chestnut parts are also removed by abrasion in great measure, but never entirely.
Female. After the autumn moult the whole upper plumage and lesser wing-coverts are a very dull blue, most of the feathers being fringed with white and with a subterminal black bar, and the feathers of the back with black shafts ; quills and remaining wing-coverts dark brown, edged with dull blue and tipped white; the whole lower plumage and the sides of the head and neck pale buffy white, each feather sub terminally margined with black ; the under wing-coverts, axillaries, and under tail-coverts suffused with rufous and irregularly barred with black. In summer all the margins of the feathers become abraded, causing the plumage to become more uniform.
The nestling resembles the adult female, but has the margins of the feathers more extended, causing a squamated appearance. The young male assumes the chestnut of the adult very rapidly and acquires the greater part of it before the autumn moult.
The females and young of this and the next species cannot be discriminated with certainty; but the females of P. solitaria are generally suffused with rufous on the under wing- and tail-coverts.
Length about 9.5 ; tail 3.4; wing 4.9; tarsus 1.2; bill from gape 1.2.
Birds of this species in typical plumage are only found in Japan and the islands of the China seas. Further west the males always exhibit some admixture of blue with the chestnut of the lower parts. The only bird killed within Indian limits that I have been able to examine at all approaching a typical Japan bird is from the Andamans. On examining all the available specimens of Blue Bock-Thrushes killed in the Indian Empire, I find that out of 102 birds from the west of the longitude of Calcutta only 8 exhibit a trace of red ; of 30 specimens from Assam down to Rangoon, only 7, and out of 72 Tenasserim birds only 27 show any red. This red is generally present on the under tail-coverts, and only in a few cases extends to the abdomen in varying quantities. The cause of this variation is unknown, but may be attributed either to climatic causes or to the interbreeding of P. cyanus with P. solitaria.
Distribution. Birds exhibiting red in the lower plumage are found in Nepal, Sikhim, Dacca, Cachar, the whole of Burma and the Andamans. This species visits the Empire in the winter only, and at this season is found also in Southern China, extending down to the Malayan islands. It breeds in Japan and Northern China.