EFFECT OF ENVIRONMENT 177 



mentioned utter recognisable imitations when caged 

 and secluded from their kind does not in any way 

 prove that their imitativeness is solely caused by 

 captivity or by modes of life incidental to that 

 condition ; although, when caged birds imitate, they 

 generally do so without any encouragement in the 

 form of desirable food from their owners. It does 

 not indicate that the dispositions of birds are in any 

 way altered by the change, except by the presence 

 of abundant food, and a consequent enforced leisure. 

 The bird is not thus changed, but its surroundings 

 are altered, and its song is subjected to fresh 

 influences, which naturally produce fresh results. 

 The fact that in most species the songs of wild 

 individuals are always of much the same characters 

 respectively (e.g. brown linnet, greenfinch, goldfinch, 

 bullfinch, blackcap, etc.), and that these birds, when 

 confined in cages near others, abandon their own 

 specific songs in favour of parts of songs of these 

 neighbours, is strong evidence upon one point the 

 great value of specific notes to birds which normally 

 employ them. It indicates the importance of every 

 class -note in the voice of a bird, whether a call 

 or a song, in the social economy of bird -life. The 

 value of such cries must be one of the chief in- 

 fluences counteracting that imitative tendency which 



