50 EVOLUTION OF BIRD- SONG 



tinually in rapid successive shrieks ; the ringed 

 plover then doubles his note (Harting, Birds of 

 Middlesex, p. 148) ; the lesser spotted woodpecker 

 repeats his only note, tic, tic, or krick, continuously 

 (Yarrell, vol. ii. p. 479) ; the pine -grosbeak also 

 repeats a call -note "with variations, sufficiently 

 often to attain the dignity of a song ' (Yarrell, 

 vol. ii. p. 183); the greenfinch prolongs the 

 repetition of his common call-note, did it it ititit, 

 and performs extravagant feats in flight ; the 

 bullfinch repeats his common call-note ; the hedge- 

 sparrow repeats his call -squeak many times in 

 succession ; and even the chissick of the pied wag- 

 tail is greatly in evidence. Then another phase 

 ensues. The creeper repeats his cry many times 

 without an interval. The greenfinch adds to his 

 common call another call-note, tell, tell, or yell, yell 

 (as it is better rendered) ; and he utters these notes 

 in a regular succession, thus producing a phrase 

 which is sung both on the wing and from a perch. 

 It may be suggested thus : Did it it itititit ; yell, 

 yell, yell ; did ititit ; yell, yell. The bullfinch varies 

 the repetition of his notes, and thus commences a 

 warble. The golden - crested wren constructs a 

 phrase by uttering his call-squeak twice in double 

 time, afterwards four times in succession, and in 



