MIMICRY IN OTHER BIRDS 227 



short note ; and the redstart also generally utters 

 towards the commencement of its phrase a much 

 shorter but otherwise somewhat similar repetition. 

 I should not consider this full, loud phrase of the 

 nuthatch as of imitative origin, for the old bird 

 utters to its young and also to its nesting- mate 

 a cry of precisely similar construction, but almost 

 toneless ; this is as it were a whispered repetition 

 of the full bubbling song, of which it is probably the 

 original. I believe that young nuthatches, when 

 crying for food to a near parent, utter this toneless 

 repetition. 



It is probable that many curious notes uttered by 

 our imitative songsters are survivals of imitations of 

 the cries of species no longer common, and that some 

 others have been acquired from foreign birds. The 

 latter feature would especially occur in the songs of 

 the sedge-warbler and other imitative summer visitors 

 to Britain. 



The reader will have perceived that my sug- 

 gestion that birds' notes, whether cries or songs, have 

 been modulated to resemble sounds with which birds 

 are familiar, is a very rational one. Analogous 

 similarities of form and colour are found in many 

 other animals and insects ; and the claim that 

 such features are developments from other types is 



