58 EVOLUTION OF BIRD- SONG 



It is not assumed that the statements in this 

 chapter can be cited as proofs that all songs have 

 been developed from call-notes ; for in some species, 

 as in the domestic cock, the attempted song is more 

 like the danger-cry than any call-note ; but I con- 

 ceive that the evidence which I have brought for- 

 ward is of value as indicating the history of the 

 songs of many species of birds. It shows that the 

 songs were, at first, mere repetitions of call -notes, 

 or possibly of defiance-cries, which have since been 

 more rapidly uttered and varied, with the result 

 that novel strains have been slowly developed. The 

 evidence adduced is but a small portion of that 

 available ; and in this respect I have here, and 

 indeed throughout the book, for the sake of brevity, 

 instanced a few diverse species as representative of 

 their respective genera. 



