SEXUAL SELECTION AND BIRD SONG. 



By Ohauncey 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 pres- 

 ent day is still held by many ornithologists to be the most satis- 

 factory explanation of the use of song as well as the best explana- 

 tion of its evolution. He maintained that the males possess- 

 ing 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 offspring — in other words, 

 would become secondary sexual characters. This Darwin called sex- 

 ual selection in distinction to natural selection, whose operation had 

 a wider scope. 



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

 guage. Sexual selection " depends on the advantage which certain 

 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 jnale offspring alone, sexual selection must have 

 come into action." * * * "A slight degree of variability, lead- 

 ing 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 most 

 vigorous and best nourished females, which are the first to breed in 

 the spring. If such females select the more attractive, and at the 



1 Reprinted by permission from the Auk, vol. xxxv, No. 4, October, 1918. 



461 



