BRITISH WARBLERS 



carried as he bends low upon the branch. During the pursuit 

 a note is uttered which, as far as my experience goes, is 

 peculiar to this particular moment, and after the pro- 

 ceedings have terminated the male shows evident signs of 

 exhaustion, for he remains panting upon a branch with 

 his bill wide open. The whole behaviour is strikingly 

 similar to that of the Willow Warbler at a corresponding 

 period. If there is any distinction between the two sets 

 of behaviour, it must be sought in the degree of expansion 

 of the wings, which after all is little enough, for the 

 quivering may develop into flapping or the napping sub- 

 side into quivering; and though experience betrays other 

 differences of minor importance which enable us to distinguish 

 the one bird from the other, yet for purposes of comparison 

 we are justified, I think, in speaking of the behaviour as 

 similar in both cases. There is one other interesting 

 feature. The females of most of the Warblers occasion- 

 ally assume, during the period of sexual activity, attitudes 

 which are characteristic of the male, but the females of these 

 two species, the Wood and Willow Warbler, are as per- 

 sistent, or nearly so, in their wing flapping as the males, 

 and not only are their actions similar to those of the male, 

 but there is also a very general resemblance in the intensity 

 of the emotional manifestation. 



As far as my experience goes the female completes the nest 

 without assistance from her mate, the work of construction 

 occupying three or perhaps four days, but she does not 

 labour throughout the day, fetching and fixing materials ; if 

 she did so the nest would probably be ready to receive the 

 eggs by the evening of the first day. What happens is this, 

 that at certain times she is seized with an impulse, which may 

 last fifteen minutes or more, to build, and during that time 

 she devotes the whole of her energy to the task. Flying 

 backwards and forwards to some spot, a few yards away from 

 the position selected, she carries leaves at one moment, 

 a piece of decayed grass at another, fixes them rapidly, 



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