EVOLUTION OF BIRD- SONG 



examples are the most pronounced : many of the 

 cries of common birds are imitated almost equally 

 throughout the year. 



MIMICRY OF THE THRUSH 



In comparing my records of the songs of the 

 thrush heard in the first months of the year with 

 those heard in May and June, a change of song, 

 similar to that shown in this table, is evident. I 

 find that in the latter period the blackbird's alarm 

 is, proportionately with the other imitations, much 

 less often uttered ; while the reproduced notes of 

 the cuckoo, wood-warbler, and butcher-bird (or the 

 note of the wryneck) then become much more 

 frequent. 



I have made a list of the subjects which I have 

 recorded as sung by all the thrushes (approximately 

 about 70 in number) heard by me in Gloucestershire. 

 It is possible that some of these birds may have 

 been counted twice over, but I exercised the 

 greatest care to avoid such an accident. The table 

 shows how many of each kind of imitation were 

 exact reproductions ; but the number of these 

 must have been greater than appears, because I 

 was not so careful as I might have been in regard 

 to this point, and sometimes forgot to note whether 



