(2086) Sterna dougalli korustes.
THE EASTERN- ROSY TERN.
Sterna korustes Hume, Str. Feath., ii, p. 318 (1874) (Andamans). Sterna dougalli. Blanf. & Oates, iv, p. 319.
Vernacular names. Muhudu lihiniya (Cing.); Kadal huruvi (Tam.).
Description. Upper parts of head to nape and crest black,, running just below the eye, where it is interrupted by a white patch; a collar on hind-neck white; upper parts pearl-grey, palest on the rump and upper tail-coverts; outermost tail-feathers pure white; first three primaries blackish with a. broad white edge to the inner webs; remaining primaries and secondaries pearl-grey, edged inwardly with white; lower plumage white suffused with delicate pink.
Colours of soft parts. Iris dark brown; bill red, tipped blackish or with the terminal third blackish ; legs and feet bright red,
Measurements. Wing 210 to 226 mm.; tail 130 to 164 mm.; tarsus about 20 to 22 mm.; culmen 31 to 38 mm.
In Winter the forehead and fore-crown are marked with white; the pink flush on the lower plumage is duller and nearly disappears.
Young birds have the upper parts white with double bars of brown; the crown streaked and the forehead spotted with brown, black and white; the rump and upper tail-coverts ashy-grey, sometimes mottled or speckled with brown; underparts white.
Nestling in down. Upper parts, chin and throat grey tinged with buff or rich buff, the bases of the down black and showing through; underparts white.
Distribution. Ceylon, Andamans and the islands of the Mergui Peninsula.
Nidification. The Eastern Rosy Tern breeds in large colonies of two hundred pairs and over in the Andamans and Ceylon, in the former during June and in the latter in April and early May. Wait and Phillips describe the nests as varying from scrapes, with little or no material as lining, to well-made pads of grass. One colony is said to have taken possession of the leeward side of an island of about an acre, where the beach shelved down to the water. Some nests were in the open and others among grass growing six inches to a foot high. The eggs numbered one or two, very rarely three and are like those of the European Rosy Tern, smaller, more speckled and less heavily blotched as a rule than the eggs of the Common Tern. In shape also they are typically longer, more pointed eggs. One hundred eggs average 40.2 x 29.3 mm.: maxima 46.8 x 28.9 and 42.1 x 31.3 mm.; minima 34.8 X 26.4 mm.
In the Andamans this Tern and Sterna sumatrana breed together, whilst in the Ceylon islands it breeds with Thalasseus bergii edwardsi, though the latter commences laying some three weeks later.
Habits. This is purely a Sea-Tern, being confined to the coastline and adjoining islands. It is resident wherever found but in the non-breeding season it scatters along the coast and among many islands, concentrating again in particular spots before breeding starts. The call is decidedly softer than that of the Common Tern but when disturbed while breeding they scream harshly as they wheel round and round the intruder. Their diet is almost exclusively small fish.