98 EGGS OF BRITISH BIRDS. 



THE WHITE-WINGED BLACK TEEN. 



(Sterna leucoptera.)* 

 Plate 29, Figs. 4, 6. 



The White-winged Black Tern is an accidental visitor to the 

 British Islands. It breeds in South Russia, Hungary, and 

 probably in the delta of the Rhone, but it only visits Spam on 

 migration. It is said to breed in Algeria and in some of the 

 islands of the Mediterranean. Further east it nests in the 

 plains of Poland and the Caucasus, and probably in Turkestan, 

 as it is a regular summer visitor to the rivers, lakes and marshes 

 throughout the extreme south of Siberia, Mongolia, and North 

 China. 



The nest resembles that of the Black Tern, and if not built 

 amongst a colony of that species, is placed in a precisely similar 

 locality, but in a colony apart. 



The eggs of the White-winged Black Tern are usually three in 

 number, but it is said that four are occasionally laid. They are 

 precisely similar to those of the Black Tern, and exhibit the same 

 variations, ranging from greyish-buff to bullish-brown in ground- 

 colour, more or less heavily spotted and blotched with reddish- 

 brown and blackish-brown. The underlying markings are pale 

 grey. The eggs vary in length from 1*4 to 1'34 inch, and in 

 breadth from l'Ol to 0'95 inch. 



THE WHISKERED TERN. 



(Sterna hybrida.)\ 



Plate 29, Figs. 8, 10. 



The Whiskered Tern is an inland species confined to the 

 tropical and semi-tropical regions of the Old World. It has only 

 occurred in the British Islands on a few occasions, and its prin- 

 cipal breeding-places in Europe are the Spanish swamps, the 

 delta of the Rhone, and the marshes of the Upper Danube in 

 Hungary, and of the Dnieper and South-west Russia. 



In North Africa it breeds more abundantly ; and small colonies 

 are to be found in Greece and Palestine. Further east it breeds 

 on the plains of the Caucasus, in Turkestan, Cashmere, and 



* Hydrochelidon leucoptera — Saunders, Manual, p, 619. 

 f Hydrochelidon hybrida — Saunders, t.c, p. 621. 



