Essays of a Biologist

by Julian Huxley

Meanwhile, they exchange some of the weed they are carrying; or at least nibbling and quick movements of the head are going on. And so they settle down on to the water, shake their heads a few times more, and separate, changing back from these performers of an amazing age-old rite—age-old but ever fresh—into the feeding- and sleeping-machines of every day, but leaving a vision of strong emotion, canalized into the particular forms of this dive and dance. The whole performance impresses the watcher not only with its strength, but as being apparently of very little direct (though possibly much indirect) biological advantage, the action being self-exhausting, not stimulating to further sexual relations, and carried out, it would seem, for its own sake.

Further acquaintance with the Grebe only deepened the interest and made clearer the emotional tinge underlying all the relations of the sexes. This bird, too, has its “greeting ceremony”; but since, unlike the colonial Herons and Egrets, it makes every effort to conceal its nest, this cannot take place at its most natural moment, that of nest-relief, but must be made to happen out on the open water where there are no secrets to betray. If the sitting bird wishes to leave the nest, and the other does not return, it flies off, after covering the eggs with weed, in search of its mate; it is common in the breeding season to see a Grebe in the “search-attitude,” with neck stretched up and slightly forward and ear-tufts erected, emitting a special and far-carrying call. When this call is recognized and answered, the two birds do nothing so simple as to fly or swim to each other, but a special and obviously exciting ceremony is gone through. The bird that has been searched for and found puts itself into a very beautiful attitude, with wings half-spread and set at right angles to the body, ruff erected circularly, and head drawn back upon the shoulders, so that nothing is visible but the brilliant rosette of the spread ruff in the centre of the screen of wings, each wing showing a broad bar of brilliant white on its dusk-grey surface. In this position it swings restlessly back and forth in small arcs, facing towards its mate. The discoverer meanwhile has dived; but, swimming immediately below the surface of the water, its progress can be traced by the arrowy ripple it raises. Now and again it lifts its head and neck above the water, periscope-wise, to assure itself of its direction, and resumes its subaqueous course. Nor does it rise just in front of the other bird; but swims under and just beyond, and, as its mate swings round to the new orientation, emerges in a really extraordinary attitude. At the last it must have dived a little deeper; for now it appears perpendicularly from the water, with a slowish motion, slightly spiral, the beak and head pressed down along the front of the neck. I compared it in my notes of ten years ago with “the ghost of a Penguin,” and that comparison is still the best I can think of to give some idea of the strange unreality of its appearance. It then settles down upon the water and the pair indulge in one of their never-failing bouts of head-shaking.

Two mated birds rejoin each other after a few hours’ separation. Simple enough in itself—but what elaboration of detail, what piling on of little excitements, what purveying of thrills!

Other emotions too can be well studied in this bird, notably jealousy. Several times I have seen little scenes like the following enacted. A pair is floating idly side by side, necks drawn right down so that the head rests on the centre of the back. One—generally, I must admit, it has been the cock, but I think the hen may do so too on occasion—rouses himself from the pleasant lethargy, swims up to his mate, places himself in front of her, and gives a definite, if repressed, shake of the head. It is an obvious sign of his desire to “have a bit of fun”—to go through with one of those bouts of display and head-shaking in which pleasurable emotion clearly reaches its highest level in the birds’ lives, as any one who has watched their habits with any thoroughness would agree. It also acts, by a simple extension of function, as an informative symbol. The other bird knows what is meant; it raises its head from beneath its wing, gives a sleepy, barely discernible shake—and replaces the head. In so doing it puts back the possibility of the ceremony and the thrill into its slumbers; for it takes two to make love, for Grebe as for human. The cock swims off; but he has a restless air, and in a minute or so is back again, and the same series of events is run through. This may be repeated three or four times.

If now another hen bird, unaccompanied by a mate, reveals herself to the eye of the restless and disappointed cock, he will make for her and try the same insinuating informative head-shake on her; and, in the cases that I have seen, she has responded, and a bout of shaking has begun. Flirtation—illicit love, if you will; for the Grebe, during each breeding season at least, is strictly monogamous, and the whole economics of its family life, if I may use the expression, are based on the co-operation of male and female in incubation and the feeding and care of the young. On the other hand, how natural and how human! and how harmless—for there is no evidence that the pretty thrills of the head-shaking display ever lead on to anything more serious.

But now observe. Every time that I have seen such a flirtation start, it has always been interrupted. The mate, so sleepy before, yet must have had one eye open all the time. She is at once aroused to action: she dives, and attacks the strange hen after the fashion of Grebes, from below, with an underwater thrust of the sharp beak in the belly. Whether the thrust ever goes home I do not know. Generally, I think, the offending bird becomes aware of the danger just in time, and, squawking, hastily flaps off. The rightful mate emerges. What does she do now? Peck the erring husband? Leave him in chilly disgrace? Not a bit of it! She approaches with an eager note, and in a moment the two are hard at it, shaking their heads; and, indeed, on such occasions you may see more vigour and excitement thrown into the ceremony than at any other time.

Again we exclaim, how human! And again we see to what a pitch of complexity the bird’s emotional life is tuned.

It will have been observed that in the Grebe, whose chief skill lies in its wonderful powers of diving, these powers have been utilized as the raw material of several of the courtship ceremonies. This pressing of the everyday faculties of the bird into the service of emotion, the elevation and conversion of its useful powers of diving and underwater swimming into ceremonials of passion, is from an evolutionary point of view natural enough, and has its counterparts elsewhere. So in the Divers, not too distant relatives of the Grebes, swimming and diving have their rôle in courtship. Here too the thrilling, vertical emergence close to the mate takes place; and there is a strange ceremony in which two or three birds plough their way through the water with body set obliquely—hinder parts submerged, breast raised, and neck stretched forward and head downward with that strange look of rigidity or tension often seen in the courtship actions of birds.

Or, again, I once saw (strangely enough from the windows of the Headmaster’s house at Radley!) the aerial powers of the Kestrel converted to the uses of courtship. The hen bird was sitting in a large bush beyond the lawn. A strong wind was blowing, and the cock again and again beat his way up against it, to turn when nearly at the house and bear down upon the bush in an extremity of speed. Just when it seemed inevitable that he would knock his mate off her perch and dash himself and her into the branches, he changed the angle of his wings to shoot vertically up the face of the bush; then turned and repeated the play. Sometimes he came so near to her that she would start back, flapping her wings, as if really fearing a collision. The wind was so strong—and blowing away from me—that I could not hear what cries may have accompanied the display.

A friend of mine who knows the Welsh mountains and is a watcher of birds as well, tells me that he has there seen the Peregrine Falcons do the same thing: the same thing—except that the speed was perhaps twice as great, and the background a savage rock precipice instead of a Berkshire garden.