436 STERNID^ STERNA 



Kirk found it breeding along with S. bergii on a low sandy island 

 at the mouth of the Zambesi in January, while Mr. Kotze sent 

 Mr. Layard an egg taken on an island in St. Helena Bay on the 

 west coast of the Colony. This egg, which is still preserved in the 

 Museum, is a moderate oval and rather rough in texture ; it is very 

 pale salmon doubly spotted and blotched with very dark purple and 

 faint grey; it measures 2-5 x 1'72 



760. Sterna bergii. Swift Tern. 



Sterna bergii, Licht., Verz. Doubl p. 80 (1823) ; Layard, B. S. Afr. p. 



370 (1867); Finsch & Hartlaub, Vog. Ost-Afr. p. 828 (1870); 



Gurney, in Andersson's B. Damaral. p. 360 (1872) ; Butler, Feilden 



and Eeid, Zool. 1882, p. 428; Sliarpc, ed. Layard's B. S. Aft: p. 



704 (1884) ; Saunders, Cat. B. M. xxv, p. 89 (1896) ; Shelley, B. Afr. 



i, p. 163 (1896) ; Eeichenow, Vog. Afr. i, p. 57 (1900). 

 Sterna velox, Cretzsclmi. in Eilpp. Atlas, p. 21, pi. 13 (1826) ; Gurney, 



Ibis, 1860, p. 221 [Durban Harbour] ; Kirk, Ibis, 1864, p. 337 



Gurney, Ibis, 1868, p. 262. 

 Sterna galericulata, Layard, B. 8. Afr. p. 371 (1867) ; Gurney, Ibis, 



1868, p. 262. 



Description. Adult in breeding plumage. A broad white band 

 across the forehead ; crown and nape black, the nape feathers 

 elongated forming a crest ; rest of the upper surface pale pearly 

 grey, paler on the tail ; primaries with the usual white band along 

 the inner edge of the inner web ; below, including the sides of 

 the face and neck white throughout. 



Iris dark brown ; bill chrome yellow, often tinged with green 

 towards the bases of the mandibles ; legs black, soles mottled with 

 yellow. Length about 19 - ; wing 15-0; tail 7'0 ; depth of the 

 fork 3-0 ; culmen 2-4 ; tarsus 1-1. 



The sexes are alike ; the adult in non-breeding plumage has 

 the crown chiefly white with black mottling, the nape feathers 

 black, but often with white tips and spots. 



The young bird has the whole of the head, including the 

 forehead, mottled with white and brown, the mantle is brown, 

 the feathers mostly edged with white ; the primaries are dark ashy- 

 brown, the tail-feathers the same, tipped with white ; under parts 

 white, sometimes a few streaks of brown on the throat and neck. 



Distribution. The Swift Tern is found along the coasts of the 

 mainland and on the islands of the Indian and Pacific Oceans, 



