THE BIRDS 



195 



themselves to the best advantage before the eyes of their 

 intended mates. Darwin attempted to account for the 

 superior qualities of the male birds by his theory of sexual 

 selection, according to which the males that were the 

 most brilliantly colored, or which sang most sweetly, or 

 otherwise displayed themselves to the best advantage 



FIG. 151. Side view of male Argus pheasant, whilst displaying before 

 female. (After Darwin.) 



would be most likely to be chosen by the females as mates. 

 Hence if this selection were continued generation after 

 generation, the males would gradually be improved in 

 respect to those qualities that appealed most strongly to 

 the sensibilities of the female birds. Almost everyone 

 has observed the strutting of the turkey gobbler with his 

 erected feathers and expanded tail, and many are doubtless 



