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 
d 
sheer “joy of life”. 
q 
Ny == 
Fig. r110.—Male Australian Bustard (O¢7s australis), 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 (Otzs tarda), 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 
(Otts austrats, fig. 1110) also has such a pouch, which in this 
case is simply a greatly dilatable part of the gullet. 
