NOTICEABLE INCIDENTS 69 



Menura Alberti as a notable exception to the rule ; 

 for the bird, " which is about the size of a half-grown 

 turkey, not only mocks other birds, but its own 

 whistle is exceedingly beautiful and varied " (Descent 

 of Man, p. 371). The crested screamer (Chauna 

 chavaria) is another exception. 



Why are singing birds small ? Is it because 

 certain female birds, in choosing their mates, have 

 always neglected the attractions of size and strength 

 in favour of music? Or is it because the larger 

 birds of a species are more attractive to the kinds 

 which prey on them, and hence have become silent 

 through fear ? Or, again, are small individuals 

 naturally more vivacious than others of superior 

 size ? Certain it is that the largest birds of various 

 races are by no means good singers (e.g. raven, 

 mistle- thrush, hawfinch, cushat or ringdove, mute 

 swan, eagle), and that some of the smallest of their 

 allies are more musical (e.g. jackdaw, nightingale, 

 linnet, turtle-dove, duck, and chanting falcon which 

 is known to sing somewhat fluently). Probably all 

 these influences have combined to render small but 

 musical individuals of various species successful in 

 the contest for mates. It is also probable that mode 

 of life has affected the development of voice as well 

 as mere size. Darwin says that " all the common 



