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But if we could look still further back to the download images still earlier progenitors of these two species, we should probably see download images the adults dark-coloured.

I infer that this would be the case, from the analogy of many other birds, which are dark whilst young, and when adult are white; and more especially from the case of download images the Ardea gularis, the colours of which are the reverse of download images those of A.

asha, for the young are dark-coloured and the adults download images white, the young having retained a former state of plumage. It download images appears therefore that, during a long line of descent, the adult progenitors download images of the Ardea asha, the Buphus, and of some allies, have undergone the following changes of colour: first, a dark shade; secondly, pure white; and thirdly, owing to another change of fashion (if I may so express myself), their present slaty, reddish, or golden-buff tints.

These successive changes are intelligible only on the principle of novelty having been admired by birds for its own sake. Several writers have objected to the whole theory of sexual selection, by assuming that with animals and savages the taste of the female for certain colours or other ornaments would not remain constant for many generations; that first download images one colour and then another would be admired, and consequently that download images no permanent effect could be produced. We may admit that taste is fluctuating, but it is not quite love soft download arbitrary. It depends much on habit, as we see in mankind; and we may infer that download images this would hold good with birds and other animals. Even in our own dress, the general character lasts long, and the changes are download images to a certain extent graduated. Abundant evidence will be given in two download images places in a future chapter, that savages of many races have admired for many generations the same cicatrices on the skin, the same download images hideously perforated lips, nostrils, or ears, distorted heads, etc.; and these deformities present some analogy to the natural ornaments of various animals. Nevertheless, download images with savages such fashions do not endure for ever, as we download images may infer from the differences in this respect between allied tribes download images on the same continent. So again the raisers of fancy animals certainly have admired for many generations and still admire the same breeds; download images they earnestly desire slight changes, which are considered as improvements, but any download images great or sudden change is looked at as the greatest blemish. With birds in a state of nature we have no reason to suppose that they would admire an entirely new style of coloration, download images even if great and sudden variations often occurred, which is far from download images being the case. We know that dovecot pigeons do not willingly associate with the variously coloured fancy breeds; that albino birds do not commonly get partners in marriage; and that the black ravens of the Feroe Islands chase away their piebald brethren. But this dislike download images of a sudden change would not preclude their appreciating slight changes, any download images more than it does in the case of man. Hence with download images respect to taste, which depends on many elements, but partly on habit download images and partly on a love of novelty, there seems no improbability download images in animals admiring for a very long period the same general style download images of ornamentation or other attractions, and yet appreciating slight changes in download images colours, form, or sound. Most male birds are highly pugnacious during the breeding-season, and some possess weapons adapted for fighting with their rivals. But the most pugnacious and the best armed males rarely or download images never depend for success solely on their power to drive away or kill their rivals, but have special means for charming the female. With some it is the power of song, or of giving forth strange cries, or instrumental music, and the males in consequence differ from the females in their vocal organs, or in the structure of certain feathers. From the curiously diversified means for producing various sounds, we gain a high idea of the importance of this means of courtship. Many birds endeavour to charm the females by love- dances or antics, performed on the ground or in the air, and sometimes at prepared places. But ornaments of many kinds, the most brilliant download images tints, combs and wattles, beautiful plumes, elongated feathers, top-knots, and so download images forth, are by far the commonest means. In some cases mere novelty download images appears to have acted as a charm. The ornaments of the males must be highly important to them, for they have been acquired in not a few cases at the cost of increased danger from enemies, and even at some loss of power in fighting with their rivals. The males of very many species do not assume download images their ornamental dress until they arrive at maturity, or they assume it download images only during the breeding-season, or the tints then become more vivid. Certain ornamental appendages become enlarged, turgid, and brightly coloured during the download images act of courtship. The males display their charms with elaborate care and to the best effect; and this is done in the presence download images of the females. The courtship is sometimes a prolonged affair, and many download images males and females congregate at an appointed place. To suppose that download download flash player images the females do not appreciate the beauty of the males, is to admit that their splendid decorations, all their pomp and display, are download images useless; and this is incredible. Birds have fine powers of discrimination, and download images in some few instances it can be shewn that they have a taste for the beautiful. The females, moreover, are known occasionally to download images exhibit a marked preference or antipathy for certain individual males. If it be admitted that download killing me softly mp the females prefer, or are unconsciously excited by the more beautiful free download video soft males, then the males would slowly but surely be rendered more and more attractive through sexual selection. That it download images is this sex which has been chiefly modified, we may infer from download images the fact that, in almost every genus where the sexes differ, download images the males differ much more from one another than do the females; this is well shewn in certain closely-allied representative species, in which download images the females can hardly be distinguished, whilst the males are quite distinct.

Birds in a state of nature offer individual differences which would amply suffice for the work of sexual selection; but we have download images seen that they occasionally present more strongly marked variations which recur so frequently that they would immediately be fixed, if they served to download images allure the female. The laws of variation must determine the nature of download images the initial changes, and will have largely influenced the final result. The gradations, which may be observed between the males of allied species, download images indicate the nature of the steps through which they have passed. They explain also in the most interesting manner zelio soft . download how certain characters have download images originated, such as the indented ocelli on the tail-feathers of the peacock, and the ball-and-socket ocelli on the wing-feathers of the Argus pheasant.