BRITISH WARBLERS 



One more question may be raised with regard to emotional 

 behaviour. Does every individual of a species respond 

 similarly under similar circumstances throughout the whole 

 of its breeding range? Beyond the fact that I have never 

 seen Marsh Warblers in this country expand their wings so 

 fully as those in Holland, I have no evidence bearing upon 

 this point. Yet more wonderful facts are to be found in 

 nature than a variation in the intensity of the reactions in 

 different geographical races ; for only if the reactions have 

 a use, and if that use bears some direct relation to the 

 particular degree in which they are executed, should we 

 expect to find them oscillating round a common mean. 



Closely connected with, but a separate aspect of this 

 emotional behaviour is the peculiar habit, common to the 

 males of certain species, of picking up and carrying decayed 

 vegetation of some description whilst they are following the 

 female during sexual emotion. We may regard this habit as 

 a stepping-stone to the next important stage in the period 

 of reproduction, the building of the nest. A reference to the 

 plates in the lives of the Grasshopper Warbler, Savi's Warbler, 

 Lesser Whitethroat, and Blackcap will convey some idea 

 of the appearance of the respective males during this peculiar 

 performance. The habit may form part of the sexual life 

 of most species, but whether it be so or not it is evident that 

 the disposition to secure and carry something is much more 

 strongly implanted in the males of some species than in those 

 of others. One would be surprised to find a male Grass- 

 hopper Warbler or Savi's Warbler that failed, when the 

 proper moment arrived, to search for, pick up, and carry a 

 piece of vegetation of some description — a decayed leaf of the 

 hazel, oak, bramble, &c, or of the common reed, as the case 

 may be — and equally surprised to find a male Willow Warbler, 

 Chiff-chaff or Wood Warbler that behaved in this way. Here 

 again all attempts at interpretation are rendered difficult by 

 the absence of anything universal. The male Whitethroat 

 builds nests even before a female has arrived, and this, 



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