THE SONG OF BIRDS 153 



passes. " Almost coinstantaneously with the hatching of the 

 nightingale's brood, the song of the sire is hushed, and the 

 notes to which we have for weeks hearkened with rapt 

 admiration are changed to a guttural croak, expressive of 

 alarm and anxiety, inspiring a sentiment of the most 

 opposite character. No greater contrast can be imagined, 

 and no instance can be cited which more completely points 

 out the purpose which song fulfils in the economy of the 

 bird ; for if the nightingale's nest at this early time be 

 destroyed or its contents removed, the cock speedily 

 recovers his voice, and his favourite haunts again resound 

 to his bewitching strains. For them his mate is content 

 again to undergo the wearisome round of nest-building 

 and incubation. But should some days elapse before 

 disaster befalls their callow care, his constitution under- 

 goes a change, and no second attempt to rear a family is 

 made." l 



As to the theoretical interpretation of bird-song, various 

 suggestions have been made. The Darwinian view regards 

 the male bird's power of song as an asset in the business of 

 courtship. The best singers were most successful in 

 wooing, and thus the musical talent was improved genera- 

 tion after generation. It is not necessary to suppose that 

 improvement always implied a structural change in the 

 song-box mechanism ; for, while that doubtless went on, 

 what was mostly selected was probably a certain type of 

 constitution an attractive fellow, in short. Nor is it 

 necessary to suppose that the coy females sit listening with 

 attentive and critical ear, like judges in a singing com- 

 petition. As we have already seen, the probability is that 

 a certain tout-ensemble of emotional display on the part 

 of the male, in which the song is one item, pulls the trigger 

 of an analogous emotional excitement in the female. There 



1 Newton's Dictionary of Birds. 



