BRITISH WARBLERS 



valleys of the Eeuse, Simmat, and Thur, and in the neighbour- 

 hood of Zurich, Brunnen, and Schwytz. In Austria the bird 

 is supposed not to be as numerous as in the adjoining countries. 

 In Hungary it is generally distributed, and in parts of Bulgaria 

 and Turkey abundant, but absent from Greece and not known 

 to breed in the Mediterranean Isles. Throughout central and 

 southern Russia, in Poland, and in the Baltic provinces, 

 where we reach its northern breeding limit in Esthonia, it is 

 generally distributed. We find it also in the provinces of 

 Orenburg, Astrakhan, the vicinity of the E. Ural, the Caucasus 

 and Trans-Caucasia, and specimens have been obtained in 

 Persia in May, probably on the way to south-east Eussia. It 

 winters in Africa as far south as Natal and Pondoland. 



LIFE-HISTORY. 



Although this bird is so closely allied to the Eeed Warbler 

 that even an expert finds it difficult to identify the dried 

 skins, yet the behaviour of the two species betrays no such 

 remarkable likeness. It is true that we can recognise many 

 points of similarity, but there are certain features which are 

 strangely different and sufficiently distinct to prevent any 

 confusion in distinguishing the living birds. The treatment 

 of the life-history of the Marsh Warbler therefore demands 

 that a series of comparisons shall be made with the cor- 

 responding behaviour in the life of the Eeed Warbler, and in 

 order to do this more completely it will be necessary to 

 review some of the points of similarity and difference in 

 the emotional behaviour of other members of this genus, 

 and make some allusion to the biological questions arising 

 therefrom. 



If we study the life of any one species and keep a careful 

 record of its actions day by day during the period of repro- 

 duction, we find that the greater part of its time is passed 

 in the performance of certain actions, the purpose of which 



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