416 



METAZOAN PHYLA 



whose wing feathers are highly developed are the birds of paradise; 

 among those which have a highly modified tail are the peafowls, lyre 

 birds, pheasants, and turkeys. 



The colors of birds are in part due to pigment; such colors appear 

 the same when seen under any condition. Other colors are produced by 

 a combination of pigment colors with interference colors resulting from 

 reflection and refraction of hght, caused in part by ridges and furrows 



Fig. 



305. — The parrot, Psittacus sp., sitting on the hand of man and conversing with him 



concerning the daily menu. 



on the surface of the feather and in part by the internal feather structure. 

 These colors are metallic and changeable. 



Birds' feathers are shed and replaced at intervals, the process being 

 known as molting. Some birds molt but once each year — early in the 

 fall — while others also undergo a partial or complete molt in the spring. 

 The spring molt is usually accompanied by the development of a highly 

 colored breeding plumage. Some changes in the color of birds are due 

 not to molting but to the wearing off of the feather tips, which are of a 

 different color from the rest of the feathers. 



