REED WARBLER 



are confronted. It almost seems as if Nature had thus supplied 

 us with a key to some of the mysteries of their existence. 

 The married life of the resident species is so gradually un- 

 folded each recurring season before our eyes, that we know not 

 with any certainty at what point sexual development com- 

 mences, and we can seldom indicate the precise moment at 

 which that mutual attraction between the sexes occurs which 

 ultimately leads to reproduction. But in the case of the 

 migratory species the conditions happily are different, for since 

 the spring migration is undertaken for the purpose of procrea- 

 tion, it is probable that the stimulus to that long and arduous 

 journey is the fact that the initial stage of the development of 

 the sexual organs has commenced. Moreover, males arrive 

 before the females, and this fact is of immense assistance in 

 helping us to trace out the true meaning of much of their 

 behaviour. 



I found, then, that many of those males that were the 

 first to reach a certain district were not passing travellers only, 

 seeking out new woods or new swamps, and leaving their 

 places to be rilled by later arrivals, but that they remained 

 more or less in that locality in which they had settled upon 

 their arrival ; and further observation went to show that this 

 locality was narrowed down to a certain territory, in which 

 the bird remained and sought its food, and which possessed 

 definite boundaries adhered to with remarkable precision, and 

 often, indeed, with an accuracy almost beyond belief . Further- 

 more I found that, when two males arrived more or less at 

 the same time in the same locality, a battle often ensued, 

 equally as desperate as those which occur amongst many 

 of the resident species at this season of the year; but inasmuch 

 as the females had not at that time arrived, it was clear that 

 they were not the direct cause of the quarrels; and, finally, 

 that in the case of adjoining territories whenever a male 

 crossed the boundary at any time during the period in which 

 the territories were adhered to, its action was generally re- 

 sented by the other male, and often led to a struggle. With 



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