178 EVOLUTION OF BIRD-SONG 



is latent, if not evident, in nearly every bird with 

 any pretensions to song. Or it may be that the 

 power of mimicry is exercised by wild birds generally 

 in an unconscious endeavour to resemble others of 

 their species a similarity of voice being an import- 

 ant aid in the distinguishing of birds of each race, 

 which more or less frequently seek each other. In 

 announcing the approach of an enemy, singing for a 

 mate, or calling to the young, a great variation from 

 a common type of exclamation would certainly be 

 injurious in effect, and would therefore be of rare 

 occurrence. If a man be taken from his native 

 country, and be placed with foreigners only, will he 

 not learn and repeat their language ? The bird 

 does the same. We should not allow our regret- 

 table ignorance of bird-song to lead us to conclude 

 that because we understand hardly anything about 

 it, the birds themselves can perceive no more mean- 

 ing in it. Their fidelity to their songs when with 

 their own species, even though dwelling within hear- 

 ing and being sometimes the companions of other 

 birds, and the sudden change of voice consequent 

 upon a total change of surroundings, are facts not 

 to be lightly passed over ; they indicate that the 

 language of the wild bird is to it as important as is 

 the language of a wild man to him. 



