Territory in Bird Life

by Henry Eliot Howard

How is its behaviour to be explained, and why did its presence cause such commotion? No one could have watched the gradual unfolding of this incident day by day and not have been impressed by the persistent endeavour with which this male maintained its position in one small part of the meadow. This is the first and most important consideration. Then there is the attitude, also significant, which it adopted towards the females; for I take it that, apart from the question of territory, the explanation of its intrusion must be sought in the necessity for securing a mate—that it was attracted by the presence of the females, and that the proximate end of its behaviour was the possession of one of them. But if there is one thing that emerges from the facts more clearly than another it is that the course of its behaviour was in no way influenced by the presence or absence of either of the females. My reasons for saying so are the following: in the first place, it made no attempt to pursue or to thrust its attention upon either one or the other of them; secondly, it even went so far as to attack and drive them away when they approached too closely; and in the third place, when an unpaired female did at length appear, it adopted a different attitude and forthwith paired. And bearing in mind that these two females had already been with their respective mates for some considerable time, and that there was reason to believe that coition had actually taken place, is it likely that any counter-attraction would have proved successful in tempting either of them away from its mate, or probable, if they were the sole attraction, that the intruding male would have been so persistent in remaining? How very much simpler it is to fit the pieces together, if for the time being we ignore the female and fix our attention upon the territory. Each item of behaviour then falls into its proper place, and the fighting which seemed so perplexing and meaningless becomes a factor of prime importance. First of all the male arrives; then it establishes itself in a small alder bush and advertises its presence by song; next, by persistent effort in attacking the neighbouring males, it frees a piece of ground from their dominion; and finally, in proper sequence, a female arrives, pairing takes place, and reproduction is secured.

How then does the whole matter stand? If it were males only that engaged in serious conflict, and if they fought only in the presence of a female, the problem would resolve itself into one simply of obtaining mates. But the warfare extends in a variety of directions, it is not confined to one sex, nor to unpaired individuals, nor need the opponents necessarily be of the same sex; it involves both sexes alike singly or combined. Now the view that the biological end of battle is, in its primary aspect, related to the female, cannot, as we have seen, apply to the conflicts between different pairs, and only by much stretching of the imagination can it be held responsible for the hostility that males frequently display towards females or vice versa. It is valid only for a certain form of warfare. But that form represents, you will say, a large proportion of the whole, which is true; and so long as we ignore the remainder, we might rest content in the belief that we had solved the major part of the problem. But can we ignore the remainder? Can we say that the conflicts between paired males, for example, are simply offshoots of the pugnacious disposition, and have no part to play in the process of reproduction? They recur with marked persistency season after season and generation after generation; they are to be found in species widely remote; they are frequent in occurrence; and no one who had observed them and noted the vigour with which they are conducted, could, I think, conclude that they were meaningless—and be satisfied. They must somehow be explained. So that if anyone thinks fit to maintain that possession of a mate is an adequate explanation of part of the hostilities, it is clearly impossible to regard all the fighting as a manifestation of one principle directed towards a common biological end.

But wherever we extend our researches, we find that the facts give precision to the view that the occupation of a territory is the condition under which the pugnacious instinct is rendered susceptible to stimulation. The Lapwing, when in its territory, displays hostility towards other males of its own species, but when upon neutral ground, treats them with indifference; the Chiffchaff pursues its rival up to the boundary and is then apparently satisfied that its object has been achieved; the cock Chaffinch in March permits no other male to intrude upon its acre or so of ground during the early hours of the morning, but for the rest of the day it joins the flock and is sociable; the Herring-Gull resents the approach of strangers so long as it occupies its few square feet of cliff, but welcomes companions whilst it is following the plough—all of which points to a relation between the territory and the fighting. And this view has at least one merit—it accounts for all the fighting no matter what degree of severity may be reached or in what way the sexes may be involved. The complexity of the strife presents no obstacle; for if the biological end of the fighting is to render the territory, which has already been established, secure from intrusion, each sex will have its allotted part to play at the allotted time: thus the battles between the males before females appear on the scene will decide the initial question of ownership; those between the females will give an advantage to the more virile members and insure an even distribution of mates for the successful males; the constant struggles between paired males will roughly maintain the boundaries and prevent such encroachment as might hamper the supply of food for the young; and the co-operation of male and female in defence of the territory will be an additional safeguard. Each form of battle will contribute some share towards the main biological function of reproduction.

Hitherto we have dealt principally with the male. We have referred, it is true, to the fact that the female co-operates with her mate in order to drive away intruders, but beyond this, we have made no attempt to trace what part, if any, she plays in the whole scheme. We must do so now.

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 that took part in it had only recently arrived, but the male, an unpaired bird, had been in possession of its territory for some days. The sequel to this struggle, which was protracted and severe, was the disappearance of both females, the male being left without a mate for a further ten days.