KKI, ATION OF SON<; TO THE TERRITORY 13 



the other, and impossible to regard the voice as 

 the medium through which an effectual union of 

 the sexes is procured. But there is reason to 

 believe that the males utilise their powers of 

 producing sound only under certain well-defined 

 conditions. For instance, when they are on 

 their way to the breeding grounds, or moving 

 from locality to locality in search of isolation, or 

 when they desert their territories temporarily, 

 as certain of the residents often do, they are 

 generally silent ; but when they are in occupa- 

 tion of their territories they become vociferous 

 and this is notoriously the case during the 

 early hours of the day, which is the period of 

 maximum activity so far as sexual behaviour is 

 concerned. So that just at the moment when 

 the sexual impulse of the female is most sus- 

 ceptible to stimulation, the males are betraying 

 their positions and are thus a guide to her 

 movements. Nevertheless, even though she 

 may have discovered a male ready to breed, 

 success is not necessarily assured to her ; for 

 with multitudes of individuals striving to pro- 

 create their kind, it would be surprising if there 

 were no clashing of interests, if no two females 

 were ever to meet in the same occupied territory. 

 Competition of this kind is not uncommon, and 

 the final appeal is to the law of battle, just as an 

 appeal to physical strength sometimes decides 

 the question of the initial ownership of a 

 territory. 



I shall try to make clear the relations 

 of the various parts to the whole with the 



