174 TERRITORY AND REPRODUCTION 



therefore apparent. Instead of this district 

 being overcrowded and that one deserted ; 

 instead of there being too many of one sex 

 here and too few of the other sex there ; instead 

 of a high percentage of individuals faihng to 

 procreate their kind, just because circumstances 

 over which they have no control prevent their 

 discovering one another at the appropriate time — 

 each sex has its allotted part to play, each 

 district has its allotted number of inhabitants, 

 and the waste of energy and the loss of time 

 incurred in the process of mating is reduced to 

 a minimum. 



Let us return again to the question of 

 fortuitous mating, and consider the position of 

 a male and female that have discovered one 

 another by accident and have paired ; what will 

 be the subsequent course-of their behaviour? 

 We are assuming, of course, that a territory 

 forms no part of their life - history. If the 

 discharge of the sexual function takes place 

 immediately and the ovaries of the female are 

 in an advanced state of seasonal development, 

 the construction of the nest will proceed without 

 delay — and the nest will answer the same 

 purpose as the territory in so far as it serves to 

 restrict the movements of the birds and tends to 

 make them remain in, or return to, its vicinity ; 

 but if not, there will be an interval during which 

 both sexes will continue to wander as before, 

 guided only by the scarcity or abundance of 

 food. In the first case, there will be the 

 attraction of the nest to prevent any untimely 



