116 DISPOSITION TO DEFEND THE TERRITORY 



one another's influence quite as readily as the 

 adjoining males and females, what would be the 

 result ? The emotional tone of the central pair 

 would stand at a lower level of intensity ; and, 

 since their congenital dispositions would lack the 

 necessary reinforcement, the birds would tend 

 to become less and less punctilious in keeping 

 their boundaries intact, whereas the adjoining 

 pairs, always on the alert and meeting with little 

 opposition, would encroach more and more and 

 gradually extend their dominion. And so, by 

 the time the young were hatched, the parents 

 would be in occupation of an area too limited in 

 extent to insure the necessarily rapid supply of 

 food, and would be compelled to intrude upon 

 the adjoining ground. But knowing how 

 routine becomes ingrained in the life of the 

 individual, knowing that for weeks this pair had 

 submitted to their neighbours, can we believe 

 that they would be capable of asserting their 

 authority and that the young would be properly 

 cared for ? Or suppose that different pairs of 

 Kittiwake Gulls on the crowded ledges, or 

 different pairs of Puffins in the crowded burrows, 

 varied in like manner, would they all have 

 equal chances of rearing their offspring ? The 

 struggle for reproduction is nowhere more severe 

 than amongst the cliff-breeding sea birds ; it is 

 not for nothing that one sees Kittiwake Gulls, 

 locked together, fall into the water hundreds of 

 feet below and struggle to the point of exhaus- 

 tion, or, as has been reported, to the point of 

 death ; it is not for nothing that Puffins fight 



