NOTICEABLE INCIDENTS 71 



The conjunctive abnormal development of the 

 organs of hearing and of the voice in birds does 

 not prove that the ear was evolved earlier than the 

 voice. However, we know that many birds with 

 acute hearing do not sing much, and also that some 

 animals which have ears have no voices such are 

 our British lizards, at least it is therefore probable 

 that the ear was developed prior to the voice, and 

 that its powers were greatly increased before the 

 voice became so strong as it is in some of our birds. 

 For the voice is only occasionally employed even by 

 some of the best singers, which are always acutely 

 sensitive to any alarming sounds. 



The present evident necessity for the frequent 

 use of the voice by arboreal birds is proved by the 

 noisiness of flocks of them, and by that of family 

 associations of a few individuals, such as those of 

 the titmice, nuthatch, etc. Birds which have hardly 

 more than one cry are compelled to make abundant 

 use of it, if they live in the obscurity of trees : such 

 are the woodpeckers. It is practically as true to say 

 that all the arboreal birds are small, as to say that 

 all the singing -birds are small ; and it is evident 

 that a life in trees is as conducive to smallness as it 

 appears to be to a development of the sense of 

 hearing. Leaf -eating and bark -boring grubs and 



