EGGS OF BRITISH BIRDS. 97 



or rare visitors; the Skuas {Stercorariince) , of which two are 

 resident, and two are visitors ; and the Gulls (Larince), of which 

 six breed in Great Britain, while nine species are more or less 

 rare visitors to our coasts. 



THE BLACK TEEN. 

 (Sterna nigra.)* 



Plate 31, Figs. 1, 3. 



The pretty little Black Tern is now, alas, only a visitor to the 

 British Islands during spring and autumn migration. Half a 

 century ago it bred every season in considerable numbers in 

 Bomney Marsh in Kent, on many of the Norfolk Broads, and 

 in some of the Lincolnshire Fens, but it is not known to have 

 remained to nest in this country for the last five-and-twenty 

 years. 



It breeds, however, in enormous numbers in various parts of 

 the Continent, from Esthonia on the southern shores of the Gulf 

 of Finland to Western Turkestan and the Altai Mountains in the 

 east. It also nests in suitable localities throughout the basin of 

 the Mediterranean, except in Egypt. 



The Black Tern is a late breeder, and it is useless to look for 

 eggs in Denmark before the first week of June, or, on the Danube, 

 before the last week of May. 



The nests are built on floating weed, and can very rarely be 

 reached without a boat ; they are placed in somewhat scattered 

 colonies, and each nest is a substantial structure of cotton reeds, 

 dead horse-tails, or decaying pond-weed or other water-plants. 



Three is a full clutch of eggs. They vary in ground-colour from 

 greyish-buff to huffish-brown, and are thickly spotted and blotched 

 with rich reddish -brown and very dark blackish -brown, with 

 underlying markings of greyish-brown and inky-grey. Few eggs 

 are more boldly marked than those of the Black Tern. On most 

 of the eggs the large blotches are confluent, often forming broad 

 irregular bands round the widest part of the shell or round the 

 large end. The eggs vary in length from 1'46 to 1*3 inch, and 

 in breadth from L05 to 0'9 inch. 



* Hydvochelidon nigra — Saunders, Manual, p. 617. 



