ROSEATE TERN. 303 



breeding-stations until towards the end of May. Its 

 favourite haunts are low, rocky islands, especially such 

 that contain reaches of sand and shingle ; in this respect, 

 as in fact in most of its reproductive economy, it very 

 closely resembles its near ally, the Common Tern. It is 

 not known whether this Tern pairs for life or not, but 

 probably such is the case. It does not appear to make 

 any nest, but lays its eggs on the bare ground, often in 

 a slight hollow amongst the shingle. Its behaviour at 

 the breeding-grounds, when disturbed, is not known to 

 differ from that of allied species. 



Range of egg colouration and measurement : 

 The eggs of the Roseate Tern are two or three in number, 

 and so closely resemble those of the Common and Arctic 

 Terns that a detailed description is unnecessary. The 

 range of colouration is precisely similar. Average mea- 

 surement, Vj inch in length, by ri5 inch in breadth. 

 The period of incubation is not known to differ from 

 that of the Common or Arctic Terns. 



Diagnostic characters : It is impossible to dis- 

 tinguish the eggs of the Roseate Tern from those of the 

 two closely allied species breeding in our area. No eggs 

 require more careful identification, and if other Terns 

 are breeding in the vicinity, the only safe way is to 

 w^atch the parent birds settle upon their eggs before 

 taking them. The adult birds may be distinguished 

 by their roseate under parts, and by the white margins 

 to the inner webs of the primaries. 



