208 TERRITORY AND REPRODUCTION 



there is no possibility of too many congregating 

 in this locality, and all the less likelihood of too 

 few finding their way to that ; and hence, on the 

 average, different pairs are distributed through- 

 out all suitable localities. Furthermore, owing 

 to the fact of their having a headquarters, the 

 male and female are allowed a freedom of 

 movement which otherwise they would only 

 possess when the construction of the nest had 

 actually begun ; they can seek their food 

 independently, and, even though paired, they 

 can if necessary continue their winter routine 

 without risk of separation. This means that the 

 organic condition which leads to pairing, is free 

 to develop in the female earlier than would be 

 the case if there were nothing in the external 

 environment to attract the pair to a particular 

 spot ; and the longer the period over which the 

 process of pairing can be spread, the greater 

 chance will females have of discovering mates, 

 the less severe will the competition tend to 

 become, and, consequently, the smaller the 

 percentage of individuals that fail to obtain 

 suitable partners. 



In these ways the territory has been service- 

 able alike to a number of species. But much 

 as the questions of mutual discovery and regular 

 distribution may have influenced the course of 

 its development, there can, I think, be little 

 doubt that, on the one hand, the supply of 

 the necessary accommodation for rearing off- 

 spring, and on the other, the necessity for an 

 adequate supply of food in close proximity to 



