^^ COMMUNITIES 203 



and destroyed the eggs, with the result that not 

 a single pair of Rooks was left in the settlement. 

 Each Rook must therefore secure a position 

 within the precincts of the community if it is to 

 have a chance of success in the attainment of 

 reproduction. But every locality cannot supply 

 sufficient trees of the right kind, appropriately 

 situated and in suitable relation to the food 

 supply, in which numbers of nests can be built 

 in close proximity ; so that if more than one 

 community were to attempt to establish itself in 

 a limited area, the supply of food or the supply 

 of trees might become a pressing problem. 

 Each community must therefore be prepared 

 to defend its own interests, and each must be 

 regarded as one unit and the area occupied 

 as one territory within which are included a 

 nunaber of lesser territories. The individual 

 may fail to establish itself within a community, 

 but, even if it succeeds, the community may fail 

 to establish the rights of communal ownership ; 

 hence it has to face a twofold possibility of 

 failure, and if it lacked the inherited nature 

 which leads the Guillemot to secure a position 

 upon the ledge, or the Bunting to obtain a 

 position in the marsh, the chances are that it 

 would fail in the attainment of reproduction. 



The question now arises as to how it comes 

 about that the area occupied by each individual 

 conforms in broad outline to that which has 

 proved beneficial for the welfare of the species 

 as a whole. We shall find that up to a point 

 the answer is a simple one. No one could study 



