528 Allen, Evolution of Bird-song. [o" t k 



would be a rather novel proceeding. The difference would be 

 fully as great and as important as the differences on which many 

 subspecies are named today, but they would be less tangible to the 

 collector, who in most cases would have to depend on the locality 

 to label his subspecies. I am rather of the opinion that the Rocky 

 Mountain birds differ slightly from the eastern ones in plumage 

 as well as in song. The naming of a new subspecies, however, 

 if grounds for such, based on plumage or measurements, exist, I 

 would prefer to leave to someone who has greater opportunities 

 to study series of skins and to work out such problems. 



THE EVOLUTION OF BIRD-SONG. 1 



BY FRANCIS H. ALLEN. 



The evidence and arguments brought forward by Mr. Chauncey 

 J. Hawkins in his paper on 'Sexual Selection and Bird Song' in 

 'The Auk' for October, 1918, make it seem very probable that 

 bird-song had its origin — its first cause — in the "maleness" of 

 the males. Mr. Hawkins fails to show, however, how the multi- 

 plicity of songs of the various species of birds, the extremely elabo- 

 rate songs of some, could have acquired their present forms except 

 by some continuous selective process. 



Mr. Hawkins concludes his paper by saying (following Brooks) 

 that "any variations in voice which might arise would be pre- 

 served in the male germ which assures the variation in the species, 

 while the germ of the female guarantees the constancy of the 

 species." I suppose this to mean that all variations that have 

 arisen in the course of the evolution of a species are present poten- 

 tially in the male germ, but that some of them are inhibited by the 

 conservative action of the female germ. This seems to be going a 

 little beyond the evidence, and it can, I think, only be regarded as a 



1 Read, in somewhat different form, before the Nuttall Ornithological Club, May 5, 1919. 



