62 THE WARBLERS 



same way to its " tee" All three species have certain notes of love, 

 war, and fear which have yet to be exactly compared and syllabled. 

 Reference will be made to some of them in the following pages. 



It is noteworthy that of these three warblers the willow-wren, 

 which has alone reached to excellence of song, is the one which has 

 thrived most in the struggle for existence. It far exceeds in numbers 

 the wood-wren and chiffchaff, and, indeed, as pointed out by Mr. 

 Bonhote, 1 none of our summer visitors appear to arrive in greater 

 myriads. Day after day, all along the south coast from Kent to 

 Land's End, thousands upon thousands pour into our Isles, some- 

 times in a continuous stream for hours at a time. During its stay with 

 us the willow-wren is to be heard almost everywhere, and frequently 

 in areas from which the chiffchaff and wood-wren are entirely absent. 

 Again, where all three occur it is, outside certain localities, by far the 

 most abundant. 



It is not possible to speak with any certainty as to the cause of 

 the numerical superiority of the willow-wren. Those that visit us 

 are drawn from a much wider area than the chiffchaff and wood-wren, 

 for the species appears to be distributed right through the African 

 continent. But this is to be considered rather as an effect of the 

 cause we are seeking than itself a cause. Ultimate analysis will 

 probably reduce the cause to a question of diet. All three species 

 are insect feeders. The wood-wren lives almost entirely, at least in 

 this country, upon trees, especially oaks and beeches. Both these 

 trees, like most others, harbour insects that are peculiar to them. 

 Now if the species has come to confine its diet mainly to these insects, 

 this fact alone would limit its spread, and consequently its increase. 

 The same applies, though to a less extent, to the chiffchaff, which is 

 seldom, if ever, found established away from the near vicinity of large 

 trees. The willow-wren, on the other hand, is seen almost every- 

 where, on gorse or hawthorn-covered commons, in reed-beds, and 

 woodland. 



1 See the " Classified Notes." 



