Page:Territory in Bird Life by Henry Eliot Howard (London, John Murray edition).djvu/164

110 The various steps by which the territory is not only established but made secure from invasion, imply an inherited nature nicely balanced in many directions—first of all the male must be so attuned as to be ready to search for a territory at the right moment; then it must be capable of selecting a suitable environment; and, having established itself, it must be prepared to defend its area from a rival, and to resist encroachment by its neighbours—and if it failed in any one of these respects, it would run the risk of failure in the attainment of reproduction. Each individual has therefore to pass, so to speak, through a number of sieves—the meshes of which are none too wide—before it can have a reasonable prospect of success. This being so, we ask, in the first place, whether the female, too, may not have an eliminating test to pass; and in the second place, whether she may not also assist in furthering the biological end of securing the territory.

Now the answer to the first of these questions will be found to be in the affirmative. Just as, in the securing of a territory, the ultimate appeal is to the physical strength of the male, so, in the course of her search for a mate, the female may be called upon to challenge, or may be challenged by a rival, and the issue is decided by force. My attention was first drawn to this fact by a struggle between two female Whitethroats, which I have described elsewhere. The scene of its occurrence was the corner of a small osier bed occupied by one male, and the females