REED WARBLER 



for possession would lead to available breeding ground remain- 

 ing untenanted. For a male when seeking a territory will 

 settle by chance in a certain place, and finding it already 

 occupied, will struggle with the owner, and perhaps be 

 defeated, or quietly pass on. In either case it may lay claim 

 to adjacent unoccupied land, but it is not unlikely, especially 

 after a fierce encounter, that it will be only too anxious to 

 abandon that immediate district, thus leaving available ground 

 in its rear unoccupied. Every male will not be compelled to 

 struggle each season for its territory ; it is clearly impossible 

 that it can be so. On the other hand, if every male has 

 always equal chances of securing a territory, and thus attain- 

 ing to reproduction, no elimination can take place and no 

 beneficial results can accrue to the species. But this will not 

 be the case ; competition will vary in different species, will 

 vary in different seasons, and even in the same species will 

 vary in different districts, according to changes of environment 

 and the rate of increase. The weaker males will often repro- 

 duce, but, taken over a number of years, the stronger will 

 reproduce more often than the weaker, and this is all that is 

 required by the theory. 



When we consider all of this, and at the same time bear in 

 mind that the reproductive instinct is possibly not so strong in 

 one male as in another, so that in the former case it may 

 soon become weary of seeking territory and be content to 

 remain unobserved in a district already tenanted, we can 

 understand that there must needs be a number of unpaired 

 birds. The pool in front of my house is generally inhabited 

 by one pair of Moorhens. One autumn both birds disappeared, 

 the one some time after the other. The pool then remained 

 unoccupied until the 16th of the following June, upon which 

 date a single individual took possession. On July 13th a mate 

 appeared, and they immediately commenced to build a nest, 

 ultimately succeeding in rearing a small brood. If territory 

 were not a necessity, why should these two solitary indi- 

 viduals of the opposite sex have waited till so late in the 



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