° 1918 ] Hawkins, Sexual Selection mid Bird Song. 421 



SEXUAL SELECTION AND BIRD SONG. 



BY CHAUNCEY J. HAWKINS. 



The place of song in the life of the bird has since the days of 

 Darwin been a question of dispute between the scientists. Darwin 

 was the first to deal with bird song in a satisfactory philosophical 

 manner. He formulated the theory of sexual selection which 

 down to the present day is still held by many ornithologists to be 

 the most satisfactory explanation of the use of song as well as the 

 best explanation of its evolution. He maintained that the males 

 possessing the best song would naturally be the choice of the 

 females ; and that the song characteristics which had made a male 

 the choice of his mate would naturally be handed on to his off- 

 spring, in other words, would become secondary sexual characters. 

 This Darwin called sexual selection in distinction to natural selec- 

 tion whose operation had a wider scope. 



To do Darwin justice we should state the theory in his own 

 language; Sexual selection "depends on the advantage which cer- 

 tain individuals have over others of the same sex and species solely 

 in respect of reproduction.". . . .In cases where "the males have 

 acquired their present structure, not from having transmitted this 

 advantage to their male offspring alone, sexual selection must 

 have come into action." . ..." A slight degree of variability, leading 

 to some advantage, however slight, in reiterated deadly contests, 

 would suffice for the work of sexual selection.". . . .So too, on the 

 other hand, the females "have, by a long selection of the more 

 attractive males, added to their beauty or other attractive quali- 

 ties." . ..." If any man can in a short time give elegant carriage 

 and beauty to his bantams, according to his standard of beauty, 

 I can see no reason to doubt that female birds, by selecting during 

 thousands of generations the most melodious or beautiful males, 

 according to their standard of beauty, might produce a marked 

 effect." " It has been shown that the largest number of vigorous 

 offspring will be reared from the pairing of the strongest and best 

 armed males, victorious in contests over other males, with the 



