Birds of Celebes: Laridae. 
901 
Three or four species have been made of the bird which we, following 
Finsch & Hartlaub, Heuglin, Salvadori, and Saunders, regard as one species 
which ranges from Australia to Japan and round the coasts washed by the 
Indian Ocean to South-west Africa. 13ut it varies locally to a considerable 
extent. “As regards size”, w^rites Mr. H. Saunders, “the smallest are those 
from the south of Australia. ... In North Australia birds are nearly as large 
as those from the Red Sea and Mekran coasts, and there is every gradation 
over the area frequented. In colour, the birds with the darkest upper parts are 
those from the Red ("“-S', velox”) and Arabian Seas and the Bay of Bengal, and 
these dark birds — slightly falling off in size — run down to the northern part 
of AustraUa (“S. pelecanoides” ) . There and in the Moluccas they meet and blend 
with the smaller southern race (“8. poliocercui' ) from which they gradually be- 
come indistinguishable. In birds from South Africa and the Mascarene Islands 
the size of the Indian form is maintained, but the tint of the upper parts is of 
a purer grey without the brownish tinge, and this also holds good of most of 
the Polynesian examples, though the latter show a slight diminution in size”. 
As the probable chief cause of these differences in tint, Mr. H. Saunders 
suggests the influence of the sun: “Under the hot sun of the Arabian and Indian 
Seas the grey feathers of the mantle and tail soon acquire a brownish tinge at 
their edges, and brown is a very assertive colour; whereas in the Southern 
Seas and in the Pacific the sun’s direct force is much feebler”. But in his ad- 
mirable catalogue (p. 14) in the case of another species, the Whiskered Tern, 
Mr. Saunders shows that Northern African examples do not attain to the dark 
hue sometimes met with in resident examples from the cooler area of South 
Africa; and Indian birds are slightly smaller in size, not among the largest. 
This species is a true Sea Tern. It breeds in large colonies, one of the 
most celebrated being that on the island of Astolah in the Gulf of Oman, made 
known in a highly interesting manner by the observations of Mr. Hume ("f>, 
28 ) and Colonel Butler ( 8 ). About 7000 eggs of this species were brought 
away by some fishermen in June, 1878. Here the birds, as Butler found, 
suffer from the depredations of a Gull; on Oyster Island near Akyab Captain 
Shopland observed that they had a great enemy to their breeding in the 
Hermit-crab, which was always ready, when opportunity offered, to seize their 
eggs ( 28 ). 
384. STERNA SINENSIS Gm. 
White-shafted Little Tern. 
Sterna sinensis {1} Gm., S. N. 1788, I, 008 (ex Latham); {2) Sauud. , P. Z. S. 1870, 662; 
{3} Hume, Str. F. 1877, V, 325; (4) Legge, B. Ceylon 1880, 1019; (5) Oates, 
B. Br. Burmah 1883, II, 430; (6) Everett, J. Sb’. Br. R. A. S. 1889, 211; 
(7) Whitehd. , Ibis 1890, 60; (8) Oates ed. Hume’s Nests & Eggs Ind. B. 1890 
HI, 312; (9) Seebohm, B. Japan 1890, 298; (10) Styan, Ibis 1891, 331, 509; 
