222 PERSONALITY IN BIRDS 



relationship subsisting between the true Thrushes 

 and the Robin and Whinchat (to take extreme 

 examples), in order to detect in the combined warble 

 and hesitating, squeaking notes of the latter birds 

 the typical form of song of the Thrush family. 



In settling points of affinity one looks first, and 

 rightly so, to the more lasting elements of structure ; 

 and no doubt to these is largely due the preservation 

 of the essential character of the son^s of birds of 



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different species of the same family, so that whilst to 

 the eye birds like the Song-thrush and Whinchat 

 may have varied almost beyond recognition as 

 derivatives from a common stock, the ear at once 

 detects their affinity through their songs. By this 

 means alone it would be possible to construct groups 

 of birds conforming to the classification resulting 

 from the more exhaustive investigations of ornitho- 

 logical science. 



To answer our first question last How came 

 different birds to have different songs ? one may 

 reply that it is mainly because they have voice organs 

 of different structure. But it is not to be supposed 

 that the notes produced by those organs are the only 

 ones that can be produced ; and thus room is left for 

 individual peculiarities. These, however, must be 

 subject to a continual process of assimilation by the 

 song and counter-song of birds of the same species, 

 so that a bird may be said to sing, first, what it can, 

 then, what it will, and finally, what it may, a 

 progression not unknown in human communities. 



Although similarity in song corresponds in many 

 cases with a deeper relationship among the singers, 

 diversity of song does not necessarily argue the 



