PERSONALITY IN BIRDS 221 



general way conditioned by difference in structure of 

 the voice organs, this is yet not so unexceptionably 

 true but that room is left for the play of individual 

 peculiarities. It is therefore pertinent to answer that 

 variation in song is now observable in birds of the 

 same species. And by variation I would not be 

 thought to mean those casual differences that may 

 be noticed in the songs of such variable singers 

 as the Tree-pipit, variations that are really but 

 transpositions of series of notes in themselves 

 invariable ; or that arise from the fact that a Tree- 

 pipit will at one time employ the whole series of its 

 different notes, while at another time it will use only 

 some of them. But by variation I would be under- 

 stood to mean some deviation from the common form 

 of song sufficiently frequent, uniform, and general, to 

 save it from being held to be casual or individual. 

 The song of the Yellowhammer may serve as an 

 example. A large majority of these birds end their 

 songs with a single, long-drawn note; but many 

 times during a season I hear in some of the finer 

 singers a second long-drawn, thinner note ; and the 

 birds that use it, although they do not use it 

 constantly, are sufficiently numerous and widely 

 distributed to save it from being considered isolated 

 or accidental. This second long-drawn, thinner note 

 occurs only after a full, vibrant emission of the 

 common song ; after a weak song it is not heard even 

 in birds which, after a strong song, use it. 



As to whether a common type may be traced in 

 the songs of birds of different species, there runs 

 throughout the Thrush tribe a distinctive type of 

 song, so that one had no need to know of the distant 



