250 WARFARE BETWEEN DIFFERENT SPECIES 



appearing, and the breeding-place of one colony, 

 that was situated in the bank of a stream twelve 

 years ago, is now buried 10 feet or more below 

 the surface of the sand. The area that was once 

 tidal, but is now a brackish lake, is fed by 

 mountain streams, and as the fresh water 

 predominates, so in course of time will it become 

 fringed with vegetation ; and instead of the 

 flocks of Curlew, Dunlin, and other waders that, 

 at low water, resorted there to feed. Coots will 

 fight with one another for the possession of 

 territories, and the Wild Duck will teach her 

 young to seek their food. 



In whatever direction we turn, we find 

 that many breeding grounds are subject to 

 incessant change. Ancient haunts disappear, 

 new ones come into being, a change which 

 makes life impossible for this bird, as likely 

 as not benefits that one, and so on. There 

 is no stability. Hence in any given district 

 each recurring season there must needs be a 

 large number of individuals which are obliged 

 to seek new stations, and if there were no 

 control over their distribution, if each one 

 were free to establish itself wherever it chanced 

 to alight, this locality might be overcrowded 

 and that one deserted ; and, bearing in mind 

 how many species there are that require similar 

 conditions of existence, we can infer that the 

 successful attainment of reproduction would 

 become impossible for many of those individuals 

 so long as each species was indifferent to the 

 presence of the others. On the other hand, if 



