(2081) Sterna melanogaster.
THE BLACK-BELLIED TERN,
Sterna melanogaster Temm., Pl. Col., pl. 434 (1827) (Ceylon) Blanf. & Oates, iv, p. 316.
Vernacular names. None recorded.
Description. Upper part of the head from the forehead to nape and crest glossy black, the extreme point of the forehead sometimes white; upper plumage grey, faintly tinged ashy, more so on the innermost secondaries; rump, upper tail-coverts and tail paler, the outer web of the long outermost tail-feathers nearly white; lores, cheeks, chin and throat pure white, shading into grey on the upper breast and thence to black on the lower breast, abdomen and under tail-coverts; under wing-coverts and axillaries white.
Colours of soft parts. Iris dark brown; bill orange-yellow, duller and tipped with dusky in the non-breeding season; legs and feet orange-red, claws black.
Measurements. Wing 221 to 240 mm.; tail 145 to 152 mm.; tarsus about 15 to 16 mm.; culmen 32 to 40 mm.
In Winter the upper part of the head is white streaked with black and there is a black patch behind the eye; lower parts white tinged with grey on the breast and fore-neck.
Young birds have the upper plumage buffy-grey, edged paler buffy-white and subedged blackish; the innermost secondaries have a second dark bar following the subterminal one.
Distribution. Practically throughout India and Burma but more rare in the South, whilst Wait does not admit it as a Ceylon bird.
Nidification. Very similar to that of the River-Tern, in company with which it often breeds, though the colonies keep separate. There is no prettier sight than hundreds of these little Terns performing evolutions over their breeding-places, their flight being most graceful and their energy inexhaustible. They nearly always select bare, open sand-banks but occasionally breed among very thin equisetum or grass. On the same sand-bank in the Brahmapootra I have seen hundreds of the River-Tern breeding on one end, many more hundreds of this little Tern at the other, whilst on the higher ground and on shingle an equally numerous colony of Swallow-Plovers were nesting. They breed in February, March and April, laying three or, not very infrequently, four eggs. In shape these are very broad obtuse ovals and in colour some shade of sandy-buff, spotted, speckled or blotched with light brown or reddish-brown, so that on dark sand they are very inconspicuous. A few eggs are greenish in colour and fewer still have a white ground. One hundred eggs average 32. 4 x 24.9 mm.: maxima 35.8 x 25.1 and 31.8 x 26.0 mm.; minima 30.2 x 25.1 and 33.3 X 23.4 mm.
Habits. Very much the same as the River-Tern, though these birds more often frequent large lakes and swamps and I have seen them fishing over flooded rice-fields. Its food is almost exclusively tiny fish and its cry is a shrill, but pleasant, " krek-krek," constantly uttered as they fly about. When fishing these Terns often disappear completely under water.