THE MOULTING OF BIRDS. 155 



these young birds are very differently attired from their 

 parents, being dull and sombre-looking, and apt to be 

 overlooked even by the most practical field naturalists. 

 This is especially noticeable in such species as Warblers, 

 Wagtails, and Pipits. 



For convenience of treatment it is best to divide our 

 British birds into four classes, quite irrespective of their 

 structural affinities. In our first division we will glance 

 at those birds which go through a complete moult twice 

 in the year, in spring and autumn ; in our second we 

 will include those which have a complete change of 

 plumage in autumn, but only a partial one in spring ; in 

 our third we will take those birds that only moult once 

 in autumn ; whilst in our last we will put those that are 

 in a more or less chronic state of moult during the 

 greater part of the year. It is well here to point out 

 that all birds moult at least once in the year, and some 

 part of the autumn or early winter is the period at 

 which this universal change of plumage is undergone. 

 As a rule, birds begin to moult soon after the breeding 

 season is over, and those species that have a double 

 change of feathers moult a second time just previous to 

 pairing, when they acquire the various nuptial or- 

 naments which render them specially beautiful and 

 attractive. 



It is a singular and interesting fact that the only 

 British Passeres or Singing Birds which have a complete 



