THE MOULTING OF BIRDS. 161 



following spring, when the scapulars and innermost 

 secondaries reach the adult stage of colour, and the 

 brown hood is assumed for the first time, but this is more 

 or less mottled with white, and the band across the tail 

 is becoming imperfect. The amount of white on the 

 primaries gradually increases for several years until the 

 bird is fully adult. The larger species, as for instance the 

 Lesser Black-backed Gull, mature even more slowly, and 

 do not obtain their adult plumage until after the fourth 

 or fifth autumn moult, when they are three or four years 

 old. The first plumage is brown on the upper parts, 

 each feather with a pale margin, and white streaked with 

 brown on the under parts, the quills uniform dark brown, 

 and the tail white barred with brown. After each 

 recurring moult in spring and autumn the signs of im- 

 maturity grow less, traces remaining longest on the wing 

 coverts and tail. The white subterminal spots on the 

 longest primaries are perhaps the last marks of maturity 

 obtained, the birds not assuming them until after the 

 fourth autumn moult. In all these young Gulls the 

 colour of the feet, bill and iris slowly changes until the 

 prevailing colour in the adult is obtained. 



We now pass to our second division, in which are 

 included those birds that have a complete moult in 

 autumn, but only a partial one in spring. Among the 

 Passeres, there are few species which moult in this 

 manner. These are the Crows, the Wagtails, and the 



M 



