Page:The British Warblers A History with Problems of Their Lives - 7 of 9.djvu/16

 valleys of the Reuse, Simmat, and Thur, and in the neighbourhood 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 R. Ural, the Caucasus and Trans-Caucasia, and specimens have been obtained in Persia in May, probably on the way to south-east Russia. It winters in Africa as far south as Natal and Pondoland.

Although this bird is so closely allied to the Reed 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 corresponding behaviour in the life of the Reed 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 reproduction, we find that the greater part of its time is passed in the performance of certain actions, the purpose of which