EEED WARBLER 



are different, aquatic insects being then plentiful, and young 

 succulent aquatic plants abundant. Or take the case of the 

 migrants after the young are reared and able to take care of 

 themselves : the parent birds do not still remain in their terri- 

 tory, but frequently separate and wander from place to place 

 with no fixed abode. It cannot therefore be the desire to 

 secure an efficient supply of food for themselves that causes 

 the Moorhens to defend their territory so stoutly, since they 

 seek for and find much of it upon neutral ground. Nor can 

 it be anxiety to prevent the possibility of lack of food for 

 themselves that impels the Warblers to struggle together, for 

 why then should they desert the territory they have won and 

 so consistently defended as soon as the young reach a certain 

 age ? As I shall presently mention, the Reed Warblers do 

 seem to regard the tops of the alders surrounding the reed bed 

 as neutral ground, resorting thereto to seek food for their 

 offspring. But their territories are small owing to the 

 comparative scarcity of suitable breeding grounds, and some 

 relaxation of the general law may be advantageous in their 

 case. 



Glancing at an early period in the history of bird life, we 

 are now in a position to understand partly what may have 

 taken place. Those members that were not pugnacious, and 

 thus allowed others to breed in proximity to them, would 

 certainly attain to reproduction, but their offspring, if they 

 did survive, would be weak owing to lack of food and exposure 

 to changes of temperature, and in their turn would produce a 

 weakly race unfitted to struggle, when called upon to do so, 

 with stronger individuals, and so the tendency to sociability, 

 having in such cases no opportunity for expansion, would 

 gradually disappear. But the necessity for a supply of food 

 in the immediate vicinity of the nest would not always have 

 been imperative, and in some cases might not have been 

 of sufficient importance to outweigh advantages gained from a 

 number of individuals congregating together, so that we should 

 then find members of one species breeding in a community. 



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