276 BRITISH BIRDS. 



with those of auy other British bird. If its eggs are taken^ which in many 

 places is systematically done, it lays again and again, but otherwise it only 

 rears one brood in the year. 



They commence to leave their colonies in the North Sea about the 

 middle of August, and by the middle of September their breeding-places 

 are deserted. In their winter-quarters on the west coast of Africa they 

 are said to confine themselves to the vicinity of the sea-shore. 



The Sandwich Tern is slightly larger than the Gull-billed Tern, but the 

 fork of the tail is nearly twice as deep (about 2^ inches). The upper tail- 

 coverts and the tail are white, and the white margins on the inner webs of 

 the quills extend to the point ; otherwise in the general colour of its plu- 

 mage, and in the successive changes which it undergoes, it agrees with the 

 group of which the Arctic Tern is typical. Bill black, with a yellow tip in 

 the adult, paler in the young. Legs and feet black in the adult, brown in 

 the young ; irides hazel. 



Young in down have the upper parts pale grey mottled with greyish 

 black, and the underparts pure white. 



