Page:The British Warblers A History with Problems of Their Lives - 5 of 9.djvu/21

 that of the Blackcap when quietly reposing, back feathers being raised, tail drooping, and breast feathers swollen out, giving them a similarly rounded appearance.

Owing to the density of the reeds, and consequently the great difficulty in studying their habits. I do not think it likely that I should ever have recognised any law of breeding territory, had I not previously known of its existence amongst so many other species, but there is little doubt that this question plays an important part in their life-history. Each male locates himself in a particular part, and a comparatively small part, of the reed bed, and inasmuch as reed beds suitable to their needs are not very plentiful, the dimensions of their territories are small. If it were not so the species would rapidly decrease, so that they differ in this respect from those migrants that inhabit many and varied situations. The males adhere more or less to a certain territory, but it is not easy to ascertain how far they struggle with one another for possession, nor whether they regard with suspicion a trespass on the part of one of their neighbours. Short but angry battles are of frequent occurrence between them for some weeks at this period. One hears the clicking of bills, and then the birds appear momentarily above the tops of the reeds, pecking at one another, and as quickly vanishing amongst the reed stems, only to reappear further away as they rapidly pursue and fight with each other. In one instance I had an exceptional opportunity of watching the behaviour of a male with regard to this question of territory. This particular bird owned a territory amongst some willows and alders adjoining a reed bed, the headquarters of his domain being a Salix bush overgrown with honeysuckle, and not more than fifteen yards away on the edge of the main portion of the reed bed was the territory of another pair. This latter pair must have arrived some few days before the former bird, because, when I commenced to watch the two territories on May 22nd, they were already building their nest. Morning after morning this single male behaved in much the same