The Courtship of Animals

by W. P. Pycraft

In all that concerns the problems of sex, which is to say of reproduction, birds, speaking generally, display a briefer and more condensed sequence of events than the mammals; and, moreover, many species compel the attention even of the most incurious, to their behaviour at this time, through the development, either of song, or of fantastic displays of their amorous feelings: while others force themselves no less conspicuously under notice by their habit of nesting in large, and often enormous colonies.

In the matter of the development of secondary sexual characters birds stand conspicuous among the Vertebrates, and easily eclipse the mammals; among which bright, strongly contrasted, colours are the exception. Among the birds they may almost be said to be the rule. Also, in this category we have to reckon song, and the production of more or less musical sounds by the agency of internal resonators or of specially modified feathers; as well as quaint forms of posturing which may be included under the head of dances. Further, some species have developed formidable weapons of offence. These things are interesting enough in themselves, but they become still more so when we reflect that they formed the corner-stone of Darwin’s theory of “Sexual Selection,” and that Wallace’s criticisms thereof were inspired by evidence from the same source.

The interests of this chapter will best be served if the evidence on which this theory was founded be first surveyed: when Darwin’s deductions and the criticism which they have aroused will be the more readily appreciated.

Definitions are always liable to exceptions; and concrete cases are better than abstract terms. Birds, then, perhaps better than any other group, illustrate what is meant by the term “secondary sexual characters,” if only because examples are so constantly at hand. Save among experts, sex among birds cannot be determined except by the differences in plumage, or sometimes in size, which the sexes display. But even here, it is only among species which occupy what we may call a mid-evolutionary phase in which this discrimination is possible. Among “generalized” species, wherein the plumage is of sombre hue, there is no external distinguishing mark between male and female; and the same is true with species which have attained to the maximum of resplendent plumage; as for example many Parrots and Kingfishers, where again both sexes, and at all ages, display the same vivid hues. Thus, in the case of either of the two extremes, the study of behaviour during the breeding season is one of great difficulty and no less uncertainty. Where the sexes are sharply distinguished by differences of coloration, however, as with the Peacock, the matter is otherwise. This bird, from time immemorial the symbol of vanity, illustrates in a singularly effective manner the broad features of what is commonly meant by “courtship” among birds, while it furnishes a no less striking example of the development of “secondary sexual characters.”

One might have supposed that birds, under the spell of that irresistible desire for sexual intercourse, would behave differently in regard to their “courtship” according to whether they were monogamous, polygamous, or polyandrous: but while their behaviour during this period of the life-history presents an extraordinary variety, it is only at any rate slightly determined by the plurality or otherwise of mates; and the same rule holds in regard to the brilliancy or otherwise of coloration.

The most common manifestation of sexual desire among birds takes the form of strange posturings which are, in some species, enormously exaggerated by the display of vividly coloured frills, tufts, or other conspicuous modifications of the normal plumage. The Peacock affords a most excellent example of this combination of the contortionist and the beau, though the nature of this display is by no means generally understood. This applies more particularly to artists, who from time immemorial to the present day, in essaying to paint the Peacock in his pride, have invariably fallen into the error of treating the great ocellated train as if it were the tail, placing it where, of course, the tail ought to be, at the end of the body! As a matter of fact it is nothing of the kind; these gorgeous plumes are really exaggerated tail-coverts which, when set on end, appear to arise from an oval shield of metallic green scales—the central back-feathers. When this trailing glory is erected, the bird throws the body forwards and downwards, so that the outermost train-feathers fall downwards on either side in front of the wings, which are more or less trailed: so that from the front only the head and neck are visible, the rest of the body being hidden behind the screen, as may be seen by a reference to the accompanying photographs. The manner of this display is extremely interesting, for the bird seems to be conscious of the effect produced: though it cannot be supposed that this is really the case.

When displaying, the bird gradually approaches the nearest female and slowly erects these extraordinary plumes. So soon as this is accomplished he begins to walk backwards towards the object of his attentions, presenting nothing but a great round shield of dull brown feathers, backed up by the tail-feathers, and the dull-coloured wings. So soon as he judges himself near enough, however, he suddenly swirls round, confronting her in all his splendour, and heightening the effect with a loud scream accompanied by a rapid, vibratory, motion of the train-feathers which produces sounds like the pattering of rain on leaves. Then he stands before her, with bowed head, as if to give her an opportunity of drinking in his splendour to the full. Commonly, however, she appears to be utterly indifferent, and either walks away or continues a real, or affected hunt for food, as if no such thing as a love-sick suitor were within a hundred miles of her! But sooner or later his suggestive attitudes beget an answering response, and pairing takes place.

The display of the beautiful Peacock Pheasant differs conspicuously from that of the Peacock, and recalls that of the Argus Pheasant. In the Peacock Pheasant, as will be seen from the adjoining photograph, the wings, and tail, are alike bedecked with ocelli. The display is made by the bird as it crouches close to the ground, with the wings and tail raised to form a continuous, patterned surface, the head being swiftly moved during the performance; hence its blurred outline in the photograph.

Plate 15.