1498. Hydroprogne caspia.
The Caspian Tern.
Sterna caspia, Pall. Nov. Comm. Petrop. xiv, i, p. 582, tab. xxii, tig. 2 (1770); Hume, S. F. i, p. 280; Oates, S. F. iii, p. 347; id. Cat. no. 982; Legge, Birds Ceyl. p. 1008; Butler, S. F. ix, p. 439; Parker, ibid. p. 487 ; Davidson, S. F. x, p. 326; Oates, B. B. p. 427 ; Barnes, Birds Bom. p. 428; Oates in Hume's N. & E. 2nd ed. iii, p. 295. Hydroprogne caspia, Kaup, Naturl. Syst. pp. 91, 196; Saunders, Cat. P. M. xxv, p. 32. Sylochelidon caspius, Brehm, Vog. Deutschl. p. 770; Blyth, Cat. p. 290; Jerdon, B. I. iii, p. 835; King, J. A. S. B. xxxvii, pt. 2, p. 218; Holdsworth, P. Z. S. 1872, p. 480; Hume, S. F. iv, p. 414.
The Largest Tern, Jerdon ; Kekra, Sind.
Coloration. In summer plumage the forehead, crown, nape, and sides of head to below the eye black glossed with dark green; remainder of upper plumage, with wings, pearl-grey; the inner webs of the primaries (and the outer webs, when the frosted surface has worn off) darker; rump and tail still paler; lower plumage with sides, and sometimes back, of neck, cheeks, and lower lores pure white.
In winter the upper part of the head is white broadly streaked with black, and there is a white collar behind the head all round.
Young birds resemble adults in winter plumage, but have more black round the orbit: at an early stage the scapulars, tertiaries, wing-coverts, and tail-feathers are dark brown or barred with brown and have whitish edges; the primaries are blackish.
Bill coral-red in summer, duller in winter, with the terminal portion dusky; irides dark brown ; legs and feet black.
Length 20; tail 5.75, depth of fork 1.25; wing 15.5; tarsus 1.75 ; bill from gape 3.8.
Distribution. .North America south of the Arctic circle, Europe as far north as 60° N. lat., all Africa, temperate and tropical Asia, the Malay Archipelago, Australia, and New Zealand. This Tern occurs in many parts of India, Ceylon, and Burma, but is by no means generally distributed. It is particularly common in Sind.
Habits, &c. The Caspian Tern occurs singly or in pairs about rivers and large pieces of water, fresh or salt, and also on the sea-coast, and it may be recognized at a considerable distance by its habit, when looking for food, of flying over the water with its bill directed downwards. It has a harsh cry, which it always utters, according to Hume, when hit by a shot, and it lives on fish and prawns. The majority of the Caspian Terns visiting India probably breed elsewhere—one great breeding-place is on an island at the head of the Persian Gulf—but this species is not truly migratory; and a small colony was found by Mr. H. Parker, in June, breeding on one of the sand-banks at Adam's Bridge, North Ceylon. One or two eggs, greyish white or buff, and double-spotted, each measuring about 2.43 by 1.70, were found in each case in a small hollow in the sand.