THE MOULTING OF BIRDS. 165 



parts and the flanks have broad pale gray margins, and 

 the sides of the head and throat are tinged with brown. 

 In the Red-throated Diver the spots on the upper parts 

 are replaced by streaks, and the ear-coverts and throat 

 are mottled with brown. Young Divers carry their first 

 plumage through the winter until the following spring 

 (not moulting in December with their parents), when 

 they assume their summer plumage, but the nuptial 

 ornaments are not so brilliant in colour as in adults. 

 In the Auks the young are hatched covered with down 

 and able to swim. Their first plumage resembles that 

 of the adult in winter plumage, and after their first 

 spring moult they do not differ from their parents in 

 any important particular. 



We now arrive at the third division of our subject, in 

 which the birds have only one change of plumage in the 

 year. This, with one or two exceptions, takes place in 

 autumn. With the exception of the Warblers, the 

 Crows, the Pipits, and the Wagtails, all the British 

 species of Passeridae are single moulted. They include 

 the Thrushes, Chats, Robins, Flycatchers, Redstarts, 

 Tits, Waxwings, Starlings, Finches, Shrikes, Swallows, 

 and Larks. Many of the birds here specified present 

 considerable differences in colour between the summer 

 and winter plumage. This change is brought about, not 

 by a moult, but by the abrasion or casting of the pale 

 edges of the feathers which conceal the brighter colours. 



