THE SONG AND NOTES OF JBIRJDS. 105 



and sexual instincts are inseparable, this display by 

 the male accompanying the vocal powers in a very 

 striking manner. 



It now becomes necessary to glance at another 

 branch of this interesting subject, namely, the 

 variation existing in the song of individuals of the 

 same species. Variation in the songs of birds is 

 almost as palpable as the variation which is so 

 characteristic of bodily structures, of habits, and 

 even of instincts. The subject has received but 

 little attention from naturalists, probably from lack 

 of a musical training or a defective ear. I feel that 

 I have missed much through my lack of musical 

 knowledge, but trust that what little I have been 

 able to gather bearing on the question may serve 

 as an incentive to more elaborate efforts amongst 

 observers whose musical training better fits them 

 for the task. One very remarkable instance of 

 variation of note came under my observation whilst 

 studying the birds of Skye. I found that the 

 Chaffinches which frequented the isolated wooded 

 district of Tallisker had quite a different note from 

 the normal one of this species. Another interest- 

 ing instance is recorded by Lord Lilford in his very 

 instructive work, Notes on the Birds of North- 

 amptonshire. He writes, "We had for some years 



