WOOD WARBLER
failures, and quite another to show how the environment can come to possess guiding value for a bird as to its future behaviour. Assuming that the facts are correct, science, I take it, has really no explanation to offer.[1]
The males, when they first arrive, are often more restless and cover a larger area of ground in their wanderings than they are wont to do a few days later. Even upon the first morning of their arrival they do not roam 'far, but confine themselves rather to that particular part of the wood in which they have settled; afterwards their wanderings become even more curtailed, and the week or so of their bachelor existence is usually passed amongst certain trees on a few acres only of ground. Consequently they own territories after the manner of other species, territories which of course vary in extent according to the nature of the environment and the proximity of rival males, but which, on the whole, are very similar in size to those of the Willow Warbler or Chiff-chaff. One curious departure from the normal routine of behaviour in regard to this question of territory came under my notice. A male that owned a territory in one corner of a large wood was wont to disappear from view for short periods of time. Located in the same wood were a few individuals of the same species, the nearest of which possessed a territory some 250 yards away. In order to solve the difficulty of the alternate presence and absence of this particular male I determined to keep him strictly in view for a time, and it soon became evident that he and the neighbouring male referred to were one and the same individual. He therefore owned two territories, in each of which he spent a portion of his time. Unfortunately I was compelled to desert him before any females had arrived, and was unable consequently to see the outcome of his peculiar behaviour. The intermediate
- ↑ On the hypothesis of germinal variation in every direction, acquired modification may here have determined the survival of variations in the direction of a more complete harmony with the environment in the way suggested by Professor Lloyd Morgan in his principle of the survival of coincident variations.
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