BRITISH WARBLERS 



is spread over some considerable time; males continue to 

 arrive up to the latter end of May and perhaps even later 

 than this, but it is impossible to say whether all such males 

 are true arrivals or simply individuals that so far have failed 

 to secure a territory. It is evident that in the case of all 

 the more common migratory species, certain individuals will 

 be compelled to wander about in search of territories, and 

 their difficulties in rinding them will be great or small accord- 

 ing to the environment which they are accustomed to inhabit. 

 The Garden Warbler can no more escape these difficulties 

 than other members of the genus. And so when we think 

 we observe fresh arrivals appropriating territories in the latter 

 part of May we may well be mistaken ; what we really observe 

 being nothing but a process of re-arrangement brought about 

 by some change in the available territories of the district. 

 A new breeding ground is often supplied by the clearing 

 away of young trees or the felling of timber in some wood, 

 and the first to take advantage of it will probably be the 

 young males of the surrounding districts, thereby temporarily 

 reducing the severity of the struggle in the immediate 

 neighbourhood. Such re-arrangements I have observed taking 

 place ; on the one hand the gradual appropriation of every 

 available space of ground, and, on the other, the gradual deser- 

 tion of territories as they became unsuited to the requirements 

 of the birds. 



The localities inhabited by the bird are similar to those 

 in which we are accustomed to find the Blackcap common. 

 Large or small woods, coppices, osier beds, wooded banks, 

 gardens, or even the outskirts of the forest, afford the 

 necessary shelter; and it would be difficult to point to any 

 one particular type of woodland for which a partiality is 

 shown. The relative number of individuals which visit any 

 one particular locality year by year is subject to some varia- 

 tion; in one season the birds may be plentiful everywhere, 

 in another only moderately so, whilst in a third scarce, a 

 peculiarity which is shared with other migrants. Of the 



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