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 Avashed by the 

 Indian Ocean to South-west Africa. But it varies locally to a considerable 

 extent. "As regards size", writes 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 Australia (''8. pelecanoides" ) . There and in the Moluccas they meet and blend 

 with the smaller southern race f">S'. poUocercus" ) from which they gradvially 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 (6, 

 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). 



-f 384. STERNA SINENSIS Gm. 



White-shafted Little Tern. 



Sterna sinensis (1) Gm., S. N. 1788, I, 608 (ex Latham); (2) Saund., P. Z. S. ISTti, 662 

 [3j Hume, Str. F. 1877, V, 325; (4) Legge, B. Ceylon 1880, 1019; (5) Gates 

 B. Br. Burmah 1883, H, 430; (6) Everett, J. Str. Br. R. A. S. 1889, 211 

 (7) Whitehd., Ibis 1890, 60; (8) Gates ed. Hume's Nests & Eggs Ind. B. 1890, 

 in, 312; (9) Seebohm, B. Japan 1890, 298; (10) Styan, Ibis 1891, 331, 509 



