250 BIRDS OF MIDDLESEX. 



disposition of their markings, that it is scarcely 

 possible to separate them when mixed. 



LESSER TERN, Sterna minuta. Examples of this 

 graceful little bird are observed here in spring and 

 autumn, but it is very irregular in its movements, 

 and is the least common of the Terns which visit us. 

 In appearance and habits it much resembles the 

 Common Tern, and its note is also similar. (See 

 ante, p. 248, note.) 



BLACK TERN, Sterna nigra. Next to the Common 

 Tern this is the commonest of the four species 

 which visit us, and is the earliest to appear in the 

 spring. In 1863 I shot one on the 25th April ; it 

 proved to be a male bird in incipient summer plumage. 

 Adult males in full summer dress are seldom ob- 

 tained, the majority of those which appear in spring 

 being old birds in winter or incipient summer plum- 

 age, and, in autumn, the females and young of the year. 



The Black Tern evinces a great partiality for 

 fresh water, and, so far as I have been able to ob- 

 serve, does not prey upon fish to the same extent as 

 its congeners. The stomachs of several which I 

 examined contained a quantity of insects. Their 

 flight is very graceful, closely resembling that of the 

 Swallow (hence the popular name of Sea-Swallow), 

 and, during May, they may be seen sporting over 

 the water in company with innumerable Swallows 

 and Sandmartins, with whom they always appear to 

 be on very good terms. 



