MIMICRY IN OTHER BIRDS 229 



similar high toneless noises. Similarly, there is 

 nothing extraordinary in a resemblance between the 

 noise one hears when pulling a large earthworm from 

 its hole (the ear being near the ground) and certain 

 low-pitched "whirry" noises often uttered by the 

 starling towards the commencement of a song. 



All evident imitations furnish proof of the influ- 

 ence of surroundings in regard to the evolution of 

 bird -voices. When we remember that probably 

 through long ages this principle has been ceaselessly 

 operating, and that its effects have not necessarily 

 been lost in each generation, but probably have been 

 perpetuated through the agency of filial imitation, 

 we need not wonder that the cries of birds (imitative 

 or unimitative) are so often somewhat similar to the 

 sounds which the birds themselves experience daily, 

 either in relation to obtaining food and to feeding 

 or to the other incidents of their lives. On the 

 contrary, it may be justly surmised that nearly the 

 whole range of bird-song may have been affected by 

 the imitative faculty, which we know to have so 

 wide-spread an influence in the animal world ; and 

 that the voice of the bird has been thus attuned to 

 harmony with neighbouring sounds, just as its colours 

 so often blend with those of its surroundings. 



