36 EVOLUTION OF BIRD-SONG 



enraged bull. I have not detected any similar 

 snapping of the bill during song, unless, indeed, a 

 certain note of the greenfinch can be considered to 

 be, as its tone indicates, modified by a rattling of 

 the mandibles during its utterance. The full song 

 of the male greenfinch may be rendered as follows : 

 Did it it ititit, tell tell tell, zshweeoo^ the zsh in the 

 last word being pronounced like the letter " s " in 

 "treasure" and "pleasure." The cry did it it it 

 is the common call of both sexes at maturity. 

 About February the male generally adds to this the 

 cry tell tell . . . ; and in March is added the zshweeoo, 

 which is never uttered before did it or tell in the 

 phrase, but often follows them, and is sometimes 

 uttered alone. This note is never uttered when 

 the male is " playing " to the female, nor when he is 

 feeding her off the nest, nor yet during flight ; but it 

 seems to be accompanied by a rattle of the bill 

 closely like that which is produced during combat 

 by this species, and by the female house-sparrow 

 when she threatens the male who is courting her. 

 For these reasons I consider this note to be a 

 defiance song-note. A very similar, but shorter and 

 much coarser, note is uttered by the goldfinch when 

 fighting ; and the lesser redpoll and (I believe) the 

 siskin furnish similar examples. 



