152 THE BIOLOGY OF THE SEASONS 



cannot do in the way of song when it is isolated from 

 its kin. 



Although there is considerable uncertainty, it seems as 

 if the general character of the voice and of the call was 

 hereditarily determined, while the actual melody is acquired 

 by education. Imitation plays an all-important part, 

 and thus much depends on those who serve as models. 

 " In places where nightingales enjoy protection from cats 

 and other persecutors, there are naturally some very old 

 birds, who improve their melodies from year to year, both 

 as regards purity and strength of notes, and thus become 

 more and more efficient teachers of youth. In such cir- 

 cumstances the nightingale's song acquires a fineness and 

 gradually increasing perfection, while in other districts, 

 where the birds never live long, the general level of musical 

 culture is low." 



Indirect evidence of the importance of imitation is 

 afforded by the well-known fact that many birds readily 

 pick up snatches of song from other birds, stealing one 

 another's music. According to Witchell, skylarks re- 

 produce the cries or songs of yellow bunting, tree-pipit, 

 swallow, blackbird, martin, house-sparrow, chaffinch, pee- 

 wit, wagtail, hedge-accentor, and so on ; but when he goes 

 on to include the " sheep's bleat," we must confess to a 

 strain on our faith. He says, however : " The * sheep's 

 bleat ' above mentioned is difficult to identify in so musical 

 a voice as that of the skylark ; it is a short but distinct 

 sound, only to be described in the word baa" 



Another fact of fundamental importance in regard to 

 bird-song is its primary connection with mating. It has 

 its roots in love-calls uttered by the excited male, and 

 producing excitement in the coy female. We must return 

 to the theory, but it is important first to note the fact that 

 song wanes away or abruptly stops as the pairing season 



