BRITISH WARBLERS
neighbourhood. Nearly all the migrants are thus affected. Hedgerows are demolished and osier-beds cleared, acres of reeds are cut down and beds of rushes mown; and bearing this in mind, how is it possible for us to conceive of the same male and female meeting year after year except in a limited number of cases? A male arrives at its former breeding haunt, finds it unsuitable, and passes on in search of a new home; a week later his former companion arrives on a similar errand, but in what a hopeless position, if just that one particular male is her ultimate goal; Nature's purpose would surely be better fulfilled if she seized the first opportunity of pairing.
The male Willow Warblers, like the males of other migratory species, seem to arrive at their breeding ground for the most part during the night, and to sing the morning after their arrival. In the earlier part of the season the frequency with which they utter their song is, to some extent, influenced by the weather. If it is cold they are more silent and by no means so active, but under ordinary conditions they sing incessantly during the first few hours of daylight. They search for food in their territories, travelling first in one direction and then in another, sometimes high up in the topmost branches of such trees as oak or ash, at other times in the undergrowth or bushes, and yet again upon the ground or even along the banks of a stream, uttering their plaintive song at intervals. When sufficient food has been found they resort to some branch, often at a considerable height from the ground, and there preen their feathers. In some cases one particular tree seems to be especially favoured, and to constitute the headquarters of the territory, from which excursions are made in different directions within the domain.
Previous to the arrival of a female excitement may be caused either by the question of territory, that is to say, by one male intruding upon another's ground, or by the presence of a pair of Chiff-chaffs who happen to have taken up their habitation in the same territory. In the first of these cases there ensue frequent pursuits or conflicts; and although such
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