226 EVOLUTION OF BIRD- SONG 



ances of its ordinary fink. Early in the spring of 

 1892, I heard at Stroud a chaffinch which uttered 

 this cry of the wagtail with the accuracy of the 

 Dursley bird. It is possible that this cry was a 

 modification of the soft chissick, which is a love-call 

 of the chaffinch. 



MIMICRY IN OTHER BIRDS 



I have heard slight indications of mimicry in the 

 linnet. There are, of course, many birds other than 

 those already recorded which imitate when wild, but 

 the above instances may to some extent indicate 

 the influence which mimicry must exercise in the 

 development of birds' songs. It would seem that 

 cries of one species may be gradually adopted into 

 the songs of other species ; indeed, the above lists of 

 imitated subjects reveal this as at least a temporary 

 occurrence. To the effects of this agency may be 

 attributed some of the similarities observable in 

 certain cries of diverse species. The long, full, 

 " water-bubble " phrase of the nightingale has always 

 seemed to me to be closely like the " water-bubble " 

 notes which form one of the most noticeable spring- 

 songs of the nuthatch. Many lesser whitethroats 

 (but not by any means all of them) utter a similar 

 long roll of very rapid, full -toned repetitions of a 



