THE ARCTIC TERN. 47 



of a mixed heap of both. From their excellence as an article of food they are 

 gathered in enormous numbers for the market. 



The nestling of the Arctic Tern, which is hardly to be told from that of the 

 Common Tern, has the back marked with black ; forehead and throat black ; 

 beneath white or isabelline, with some brown on the flanks and hind abdomen. 

 "When its breeding places," writes Dr. Macgillivray, "are invaded it evinces 

 great anxiety and petulance, flying up and meeting the intruder, screaming out 

 its creaking cries, hovering and bounding around him, sweeping close to his 

 head, and sometimes, though very rarely, hitting him with its wings." 



The young birds remain close to the nesting place till they are fully fledged. 

 They have then the feathers of the upper surface, wings and tail pale pearl-grey, 

 with subterminal bars of sandy-buff; a dark grey band on the upper wing- 

 coverts ; the forehead white, the hind part of the head and the ear-coverts greyish 

 black, or mixed with whitish spots ; the cheeks, back of the neck and the lower 

 parts buffy-white, sometimes tinged with pearl blue ; feet for several months 

 3'ellowish, afterwards brown ; the bill yellow at the base and corneous at the tip. 



Young Arctic Terns may be distinguished a by no means easy task on a 

 general survey from the young of the Common Tern, by the length of the tarsus 

 and by the larger amount of the white colour on their outer primaries. 



The young birds are hardly well fledged till they begin to lose, generally by 

 pigment changes, occasionally by moult, the buff of the upper surface for a 

 cloudy white, while the dark brown or greyish black bars become paler. The 

 forehead and crown are then nearly white ; the under-surface white ; the bill and 

 feet black. 



After their first spring the black of the head is much mottled with white. 

 After their first true moult in the second autumn, the birds assume a dress 

 differing from the adults' winter plumage in having the crown and forehead 

 almost white ; the dark grey band on the upper wing-coverts continues as in the 

 younger plumage, but there is more grey on the outer webs of the tail feathers ; 

 the bill and feet are black. 



The moult of the following spring brings the young Arctic Tern into its 

 first nuptial dress, above described ; while after its next autumn change, following 

 immediately after the breeding season, it assumes its first adult winter garb, 

 which differs from its just discarded dress by the black on the forehead and 

 crown becoming mottled with white, while the under surface becomes whiter, and 

 the bright red of the bill and feet loses its brilliancy. At the end of the 

 breeding season the young birds, after they have' taken charge of their own 

 destinies, very often assemble together till August when they begin to migrate 



