126 E VOL UTION OF BIRD-SONG 



poll. It is curious that upon certain occasions the 

 common caged canary utters a note similar to this 

 one of the greenfinch. It is often uttered in the 

 presence of a stranger. The note of the greenfinch 

 is sometimes uttered alone, but never in the song. 

 The loud zshiveeo of the greenfinch has already been 

 described (ante, p. 36). Dr. A. G. Butler informs 

 me that the zshweeo of the greenfinch is sung also 

 by the brambling. The goldfinch utters a similar 

 but very much shorter sound when attacking 

 another ; so also does the lesser redpoll, and in 

 March the latter makes frequent use of the note. 

 This sound has been alluded to in relation to the 

 influence of combat (ante, p. 36). When the 

 female house-sparrow is threatening a male who is 

 " playing " to her, she produces a low rough note, 

 of even pitch, which is seemingly produced partly 

 by a very rapid vibration together of the mandibles. 

 These birds, and especially the greenfinch, when 

 taken in the hand, produce a similar sound. The 

 penultimate syllable (to borrow a term) of the song 

 of the chaffinch seems to be an abbreviation of 

 the zshweeo of the greenfinch. It is early acquired 

 by the chaffinch when recovering or developing 

 the spring song. 



In some country districts the song of the 



