With the advent of the females the amorous instincts of the male speedily gather force; but for their satisfaction it is imperative that the female should be possessed by a like desire. To provoke this, for it is essential to the well-being of the race that offspring should be produced as early as possible, some form of aphrodisiac seems to be necessary. This fact has never been properly realized, though it is implied in Darwin’s theory of “Sexual Selection.” Here, however, it was used to account for the evolution of resplendent coloration, eccentric postures, and dances which, it was assumed, enabled or induced the female to choose the most mettlesome males. What obtained among sombre-clad species, appears to have excited no curiosity among the students of the evolution theory. Hence it comes somewhat as a surprise to find that the soberly-clad Warblers behave exactly as though they too wore coats of many colours. After what has been said in the last chapter on this head it will be unnecessary to describe these displays among the Warblers in detail, more especially as my friend Mr. Howard has kindly allowed me to use some of the illustrations from his book. These show convincingly enough that the wings and tail are made to play the same part as though they bore all the hues of the rainbow. To bring this fact home compare the figures of some of these small birds clad in sober russet and black with that of the Sun Bittern (_Eurypyga helias_) in like mood, whose wings and tail when spread, and only then, display bands of vivid chestnut-red, contrasting with bands of black, on a background of grey and buff, variegated with delicate mottlings and vermiculations of black and brown, and streaks of white. In the case of the Warblers, it is to be remarked, the male, in these ecstatic moods, will commonly hold a leaf, or a piece of stick, in his beak, as if suggesting the work of nest-building and its delightful sequence. This, or its equivalent, is a common phase, for the Great Crested Grebe, for example, in these paroxysms will dive and bring up weed, the nest material of the species, as an offering to his mate, or as a stimulant to her yet slumbering passion.