BRITISH WARBLERS 



calls forth unusual energy and effort on the part of an insect- 

 ivorous species; otherwise it must succumb. . And doubtless 

 it is this great activity which enables the Chiff-chaff in the 

 latter part of March to discover sufficient insect life to prevent 

 such an undue lowering of its vitality as might "render it less 

 able to withstand the cold inclement weather so common at 

 that season of the year. Nevertheless, if we regard the relative 

 positions of the two species, we must conclude that the 

 greater strength of the Willow Warbler, which enables it with 

 more certainty to secure a breeding territory, is of higher 

 importance than the activity of the Chiff-chaff, "since the 

 former bird is more plentiful and more generally distributed 

 than the latter. 



There seems to be some connection between the song — or the 

 sounds that answer to song — and the territory. The actual song- 

 is in the case of many species so remarkable and beautiful that 

 it at once arrests our attention, and we naturally ask ourselves 

 the meaning of it, whence it originated, or how it developed. 

 To these questions no satisfactory answer has yet been forth- 

 coming. Just why a Blackcap can produce such very beautiful 

 notes and a Grasshopper Warbler such peculiar and mono- 

 tonous ones is as great a mystery to-day as ever, and I do not 

 pretend to be able to throw any light on the mysterious aspect 

 of it, but only to indicate one direction in which it may be of 

 some use. We must dismiss from our minds all ideas of 

 aesthetic value, for it is clear that if there be any utility attached 

 to the various cries, those which may sound to our ears harsh 

 or even repulsive must, if uttered under similar conditions and 

 at a similar season, be of equal importance to those which 

 delight us with their beauty. The males of the summer 

 migrants reach their destination many days before the females, 

 take possession of their territories, and there remain singing 

 incessantly during the first few hours of daylight, and in a 

 lesser . degree throughout the remainder of the day. The 

 males of some of the resident species, the Chaffinch for instance, 

 take possession of their territories very early in the year, and 



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