1084. Collocalia francica.
The Little Grey-rumped Swiftlet.
Hirundo francica, Gmel. Syst. Nat. i, pt. ii, p. 1017 (1788). Collocalia francica, G. R. Gray, List Spec. Birds B. M., Fissirostres, p. 21 (1848); Walden, Ibis, 1874, p. 132 (part.) ; 1876, p. 356 (part.); Hartert, Cat. B. M. xvi, p. 503. Macropteryx spodiopygia, Peale, U.S. Expl. Exped. p. 170, pl. 49 (1848). Collocalia spodiopygia, Hume, S. F. i, p. 296; ii, pp. 102,160; iii, p. 318; id. Cat. no. 103 quat. ; Hume & Dav. S. F. vi, p. 51 ; Oates, B. B. ii, p. 8 ; id. in Hume's N. & E. 2nd ed. iii, p. 35. Collocalia inexpectata, Hume, S. F. i, p. 296 ; Hartert, Cat. B. M. xvi, p. 505 (C. francicae subsp.). Collocalia fuciphaga, apud Blyth, Birds Burm. p. 85 ; nec Thunb. Collocalia merguiensis (C. francicee subsp.), Hartert, t. c. p. 506.
Zee-wa-so, Burmese (generic).
Coloration. Very similar to that of C. innominata, but the size is smaller and the tarsi are naked. The rump-band varies in distinctness, being ill-defined and brownish grey in Andaman birds (G. inexpectata), greyish white and well marked in those from Tenasserim (C. merguiensis). The pale rump-feathers are always dark-shafted, those of the lower surface sometimes.
Bill black; irides very dark brown ; legs and feet brown (Davison).
Length 4.75 ; tail 2.1; wing 4.7 ; tarsus .4.
Distribution. Islands of the Pacific and Indian Oceans from Samoa to Mauritius, ranging and breeding throughout the Malay Archipelago to the coasts of Burma (Tenasserim and Arrakan) and the Andaman and Nicobar Islands.
Habits, &c. So far as is known, this bird, which produces the best kind of the edible birds' nests of commerce, keeps mainly to the sea-coast. The nests are entirely, as Hume has shown, composed of inspissated saliva; they are white except where they are fastened to the rock. The breeding-season in the islands of the Bay of Bengal begins in March. Eggs measure .81 by .53.