The Body of a Bird 



293 



It is generally thought that the fact that, in captivity, 

 Purple Finches and orioles frequently moult into yellow- 

 ish hues, instead of their rightful tints, is due to some 

 change in food. Indeed in man}' species the bright colours 

 are wholly lacking after a 3'ear or two in captivity. But 

 I have transferred a male Purple Finch, ^^•hich had for 

 several years moulted 3'ellow, from a dark cage to one 

 which was exposed to 

 bright sunlight, and in 

 one moult the bird as- 

 sumed his original and 

 normal colour. 



A more probable ex- 

 ample of the effect of 

 food upon colour is seen 

 in our American Flamin- 

 goes. In captivity these 

 birds fade out moult by 

 moult, until they become 

 almost white, like the 

 European species. By 

 mixing with their food 

 a quantity of some 

 strong but harmless dye, 

 I have had them either retain their original colour for 

 years, or at least the fading process has been appreciably 

 lessened. 



The effect of climate upon colour is even more readily 

 proved, and may be noticed in wild birds as well as in 

 those in captivity. In regions which have a very dry 



Fig. 233. — Effect of environment on Bob- 

 white, shown by specimens from Min- 

 nesota, Florida, and Cuba. (From a 

 photograph provided by the American 

 Museum of Natural History.) 



