of 



go out of fashion, and the change, the moult, is a 

 mere matter of style. 



But the annual moult, first of all, is Nature's wise 

 provision for the safety and warmth of the bird. 

 Feathers are not only covering, as our clothes, but 

 also means of locomotion, and, hence, the bird's very 

 means of life. A year of use leaves many of the feath- 

 ers worn and broken, some of them through accident 

 entirely lost (as with my crow), and while they might 

 last for two years, or even longer, Nature has found 

 it necessary to provide a new plumage as often as 

 once a year, in order to keep the race of birds at 

 its best. 



But there are other reasons, at least there are ad- 

 vantages taken of the moult for other ends : such as 

 the adaptation of the feathers to the varying tem- 

 peratures of the seasons, heavier in winter and 

 lighter in summer ; also the adaptation of the color 

 of the plumage to the changing colors of the en- 

 vironment, as the change from the dark summer 

 color of the ptarmigan to its snow-white winter 

 plumage to match the snows of its far northern 

 home ; then, and perhaps most interesting of all, is 

 the advantage taken of the moult, for the adorning 



140 



