Bird Watching. Edmund Selous
those undoubted displays made by the male bird to the female, on which the theory of sexual selection is chiefly based? That the male birds should, in the beginning, have consciously displayed their plumage, in however slight a manner, to the females, with an idea of it striking them, seems improbable, and, even if we might assume the intelligence requisite for this, the theory of sexual selection supposes the beauty of the plumage to have been gained by the display of it, not that the display has been founded upon the beauty. Then what should first lead a bird of dull plumage consciously to display this plumage before the female? A mere habit of the male, increased and perfected by the selective agency of the female (as this is explained by Darwin), has hitherto—as far as I know—been considered a sufficient explanation of the origin and early stages of such displays as are now made by the great bustard, the various birds of paradise, or the argus pheasant. But if we can show a likelihood as to how this habit has arisen we are, at least, a step farther forward, even if a slight difficulty has not thereby been removed.
Now, with regard to these wheatears, it will, I think, be admitted that the little frenzies of the male birds—as I have described them—were of a very marked, and, indeed, extraordinary nature, and also, perhaps, that it is more easy to look upon them as sudden bursts of excitement—nerve-storms or emotional whirlwinds, so to speak—than as displays intended to attract the attention of the female bird. Certainly there was nothing like a set display of the plumage; and, with regard to the female, the question arises, Where was she, at least during the greater part of the time? The two male birds in the course of their drama got over a considerable amount of ground, and constantly flew from one part to another, so that, in order to have had anything like a good view, the female must have accompanied them, and I must then, perforce, have seen her, which I did not, except on the occasions related. She was, therefore, not with them, and, if watching them at all, could only have been doing so from such a distance that the dancings of the male birds would have been very much thrown away. Yet that she took some interest in what was going on appears likely from her flying up twice into the willow tree during its continuance, and being with the two rivals at the end of the day. She might, too, have been listening to the song and observing the flights up into the air, which would have been much more noticeable from a distance.
One might expect a female bird to take some interest in two male ones fighting for her merely, without any adjunct, and if they added to the fighting peculiar violent movements, such as those here described, that interest would tend to become increased. Now I can imagine that with this material of violent motions on the one side and some amount of interested curiosity on the other, the former might gradually come to be a display made entirely for the female, and the latter a greater or lesser degree of pleasurable excitement raised by it with a choice in accordance, which is sexual selection. And that the display would come at last to be made intelligently, and with a view to a proposed end—as in the case supposed of the female wild duck (or other bird) diverting attention from its young—I can also understand. In both instances mere nervous movements due to a high state of excitement would have been directed into a certain channel and then perfected by the agency either of natural or sexual selection.
On this view the curiosity (passing insensibly into interest and satisfaction) of the female bird would have been directed, at first, not to the plumage but to the frenzied actions—the antics—of the male, and he, on his part, would have first consciously displayed only these. From this to the more refined appreciation of colours and patterns may have been a very gradual process, but one can understand the one growing out of the other, for waving plumes and fluttering wings would still be action, and action is emphasised by colour.
Where, however, such movements had not been seized upon and controlled by the latter of these two powers—i.e. sexual selection—(and there is no necessity that they should be), we should have antics not in the nature of sexual display properly speaking, but which might yet bear a greater or less resemblance to such. That this is, in fact, the case has been pointed out by the opponents of sexual selection, and often as if it were evidence against it (though no one, unfortunately, can point to men as a ground for disbelief in armies). Mr. Hudson, for instance, in his very interesting work, "The Naturalist in La Plata," after bringing forward a number of cases of curious dance-movements (or of song), performed by birds, and which are, in his opinion, not to be explained on the theory of sexual selection, says, in regard to other cases brought forward by Darwin in support of that theory:
"How unfair the argument is, based on these carefully selected cases gathered from all regions of the globe, and often not properly reported, is seen when we turn from the book[11] to nature, and closely consider the habits and actions of all the species inhabiting any one district!"
[11] But from which "book"? Not, I suppose, from Darwin's alone.
Now, had Darwin been of opinion that antics performed by a bird which could not, or could not easily, be explained by his theory, were fatal to it in other cases—if he had thought that the one was inconsistent with the other—then, no doubt, it would have been unfair on his part to have marshalled the affirmative evidence without concerning himself with the negative. But why should he have held that view, or on what good grounds can such a view be maintained? As well might it be argued—so it appears to me—that woollen or other goods could only have been produced through the action of the loom, or some such special machinery. But let the wool be there, and it can be worked up in various ways. Mr. Hudson would account for all such displays or exhibitions by "a universal joyous instinct" present throughout nature, but to which birds are more subject than mammals. I do not dispute the instinct—or rather, perhaps, the emotion—or that some of the displays in question may be due to it simply and solely: but I cannot believe that all are. Why should this be the case, or how can movements which are often of a complex and elaborate nature be explained solely by reference to some large general factor, such as joy or vital energy? These may lie at the root of all; but something else, some more special process is, I think, in many cases required. One would not be content to explain all the phenomena of history by a reference to human nature, and though it may be true, as the Kaffirs say, that in a cattle-kraal there can only be one bull, yet nature is a good deal larger than a cattle-kraal. I believe myself that various antics which are performed by birds have grown out of various nervous, excited, or automatic movements arising under the influence of various special causes. Two such possible causes—viz. (1) sudden alarm whilst incubating, and (2) paroxysms of rage or nervous excitement during rivalry for the female I have already indicated. Two other possible ones have also been suggested to me by some of my observations, and I will now, by the aid of these, make an attempt—I daresay a lame one—to throw light on the possible origin of a very extraordinary case of bird-antics, described by Mr. Hudson in the work I have mentioned, and which is believed by him to be unique.
The bird in question is the spur-winged lapwing, and the following is Mr. Hudson's account of its performances:—
"If a person watches any two birds for some time—for they live in pairs—he will see another lapwing, one of a neighbouring couple, rise up and fly to them, leaving his own mate to guard their chosen ground; and instead of resenting this visit as an unwarranted intrusion on their domain, as they would certainly resent the approach of almost any other bird, they welcome it with notes and signs of pleasure. Advancing to the visitor, they place themselves behind it; then all three keeping step begin a rapid march, uttering resonant drumming notes in time with their movements, the notes of the pair behind being emitted in a stream, like a drum-roll, while the leader utters loud single notes at regular intervals. The march ceases; the leader elevates his wings and stands erect and motionless, still uttering loud notes; while the other two, with puffed-out plumage, and standing exactly abreast, stoop forward and downward until the tips of their beaks touch the ground, and, sinking their rhythmical voices to a murmur, remain for some time in this position. The performance is then over, and the visitor goes back to his own ground and mate, to receive a visitor himself later on."
Now the most curious point in this remarkable performance, so well described, is that three birds—a pair (male and female), and one other, whether male or female is not stated—take part