Page:The British Warblers A History with Problems of Their Lives - 8 of 9.djvu/53

 some Wood Warblers in this connection. The timber was felled and the undergrowth cleared in a wood of some hundred acres in extent, which for many years previously had been left untouched. In the following season, amongst other warblers which now found therein a congenial home, some Wood Warblers appeared, and each in due time secured a female, and I believe reared their young successfully. The next year two males appeared on May 3rd, and on the morning of that date were decidedly hostile to one another, but on May 4th and 5th there was no sign of these two males, nor were there any fresh arrivals. On May 6th two males again appeared and were unusually restless in their behaviour, wandering from place to place, and when in the same neighbourhood attacking one another. On May 7th one bird only was singing, and again on May 8th, but on this latter date the second male was again in evidence pursuing individuals of other species in his immediate vicinity. After this date these two males vanished, and there was no further sign of the species in the wood that year, nor did any individuals remain td breed in the following season. The behaviour of these two males differed in one important particular from the normal behaviour of the species: they were restless; instead of roaming about within the precincts of a territory, they extended their wanderings, first in one direction, then in another, and even went so far as to seek a resting-place in the opposite end of this large piece of woodland. Something was evidently amiss; a check had somehow been imposed upon the normal routine of instinctive activity, and it is my belief that the birds deserted the wood owing to its having become unsuitable so far as reproduction was concerned. The previous season they were there, content to remain in their territories and await the advent of the females, but a change had since taken place in the character of the wood, the open leaf-covered spaces, which could afford the necessary shelter for the nest, were gradually being swallowed up in a jungle of undergrowth, and the birds could not do otherwise than retire if they were to