100 BIRDS IN TOWN AND VILLAGE 



bird's song, although he can and does, as we have 

 seen, imitate its chuckling cry. 



There is another thing to be considered. I 

 believe that the bird, like creatures in other 

 classes, has his receptive period, his time to learn, 

 and that, like some mammals, he learns every- 

 thing he needs to knoY\^ in his first year or two; 

 and that, having acquired his proper song, he 

 adds little or nothing to it thereafter, although 

 the song may increase in power and brilliance 

 when the bird comes to full maturity. This, I 

 think, holds true of all birds, like the nightingale, 

 which have a singing period of two or three 

 months and are songless for the rest of the year. 

 That long, silent period cannot, so far as sounds 

 go, be a receptive one; the song early in life has 

 become crystallized in the form it will keep 

 through life, and is like an intuitive act. This 

 is not the case with birds like the starling, that 

 sing all the year round — birds that are naturally 

 loquacious and sing instead of screaming and 

 chirping like others. They are always borrowing 

 new sounds and always forgetting. 



The most curious example of mimicry I have 

 yet met with is that of a true mocking-bird, 



