150 ASSOCIATION OF ORGANISMS THE WEB OF LIFE 



always chooses the best singer, and that in a state of nature 

 the female finch selects that male out of a hundred whose notes 

 please her most '. There can be no doubt that birds closely 

 attend to each other's song." It seems, however, to be certain 

 that birds take a delight in their musical powers quite apart from 

 the question of courtship, often singing from emulation or from 

 sheer "joy of life". 



Fig. 1 1 io. Male Australian Bustard (Otis aus trails), with Throat-pouch inflated 



It is almost superfluous to remark that in appraising the attrac- 

 tions of male birds we must remember that what to us is merely 

 comical, may nevertheless be well adapted to its purpose. In the 

 Common Bustard (Otis tar da), for instance, the male indulges 

 in strange antics and displays of plumage, and often possesses a 

 large pouch that can be dilated to serve as a resonator, no doubt 

 making the love-call more sonorous, though this is no more than 

 the syllable " oak " often repeated. The Australian Bustard 

 (Otis aus traits, fig. mo) also has such a pouch, which in this 

 case is simply a greatly dilatable part of the gullet. 



