160 EVOLUTION OF BIRD-SONG 



prey ; or whether animals thus protected exercise 

 an appreciative choice, or are instinctively impelled 

 when seeking positions in which their imitativeness 

 is most effectually protective are themes foreign to 

 the subject of this chapter. Nevertheless, we should 

 remember that the distinction between appreciative 

 choice and instinctive choice is rather narrow. In- 

 voluntary imitation, such as that of young birds 

 learning the notes of their parents, is generally per- 

 petuated by inherited tendency ; and this, together 

 with the protection afforded by imitation, no doubt 

 chiefly perpetuates some of those common features 

 by which each species of animal is distinguished. 

 The power of filial mimicry is evidenced by the 

 behaviour of the house-sparrow, which, though (as 

 will be seen) endowed with imitative tendencies, has 

 preserved its language on the American continent. 

 At Montreal I heard the sparrows employing all 

 the cries of the British birds (see p. I 30). 



Imitation is occasionally exhibited in the voices 

 of animals other than birds. Several dogs have 

 been taught to utter sounds which resembled words, 

 and I have observed a remarkable instance of similar 

 mimicry in a Dandie Dinmont terrier which belongs 

 to my brother. When the terrier was about two 

 years old, a friend stayed with us, who had with 



