Among our native birds, the only other species which habitually, and especially during the courting season, produce characteristic sounds during flight, by bringing the wings smartly together over the back, is the night-jar. But there are certain small passerine birds, known as mannikins, inhabiting the forests of South America, which have the shafts of the quill-feathers of the fore-arm enormously thickened. By means of these transformed and translated "castenets," at will, the bird can produce a sound which has been likened to the crack of a whip. So far this discourse has been concerned solely with "courtship" flights, or flights associated with peculiar sounds, dependent on rapid movements of the wing in mid-air for their production. And with the mention of these instances this Chapter might, quite legitimately, be brought to an end. But it must not. And this, because there are a number of birds which put their wings, during Courtship season, to very different purposes. Spectacular flights and evolutions in mid-air do not appeal to them. They use their wings instead as lures, as a means of adding intensity to strange poses and pirouettings; whereby they desire to give expression to the amorous feelings which possess them, in the hope--if for the moment, we may accord to them human standards of intention--of arousing kindred emotions in their mates. Darwin was the first to draw attention to these curious displays. Which, on the evidence then available, seemed always to be made, and only to be made, by birds having wings conspicuously coloured. It seemed as though the possessors of such wings were conscious of their beauty, and so displayed them that nothing of their glory should be missed. The sun-bittern affords a case in point. This bird, a native of Brazil, is soberly, but very beautifully coloured when at rest; its plumage presenting an indescribable mixture of black, grey, brown, bay, and white; blended in the form of spots, bars, and mottlings. But during times of sexual excitement it will spread out its wings in the form of a great fan, encircling the long, slender, neck. And in this position they present a very conspicuous appearance, taking the form of beautifully graded bands of black, white, and bright grey, forming patterns which vanish the moment the primaries fall into their place behind the quills of the fore-arm. But when thus spread the bird seems to find the greatest delight in displaying their chaste splendour before his mate. He seems to spread his wings just because he is conscious of their beauty when thus opened out.