24 THE STORY OF THE BIRDS 



amongst secondary sexual characters. There 

 are, however, one or two exceptions to this rule, 

 the Phalaropes, the Dotterel, and certain Parrots 

 furnishing us with instances in which the female 

 is most brilliantly adorned. The colour of a 

 bird's plumage in a great many instances varies 

 considerably according to season, and in some 

 cases great difference is produced by a long 

 fringe of barbicels that conceal much of the 

 conspicuous tints on the rest of the plumage, 

 and which abrade and drop off as the breeding 

 season approaches, but these matters are perhaps 

 best dealt with when we come to consider the 

 moulting of birds. Incidentally we may remark 

 that the Snow-Bunting and the Brambling 

 present us with two capital instances of this 

 peculiarity. The correlation of colour with en- 

 vironment is another branch of this interesting 

 subject. Most readers may recall how birds of 

 white plumage usually live amongst snow-clad 

 localities, as for instance the Snowy Owl and the 

 Ptarmigan ; how others that dwell in deserts 

 and on sandy plains are clothed in plumage in 

 which brown or yellow predominates ; how so 

 many forest-haunting species such as Parrots, 

 Fruit Pigeons, Barbets, and so on, are of tints in 

 which green largely prevails. These are in most 



