There are many birds both sexes of which are conspicuously, though not brilliantly coloured, such as the numerous black, white, or piebald species; and these colours, are probably the result of sexual selection. With the common blackbird, capercailzie, black-cock, black Scoter-duck (Oidemia), and even with one of the Birds of Paradise (_Lophorina atra_), the males alone are black, whilst the females are brown or mottled; and there can hardly be a doubt that blackness in these cases has been a sexually selected character. Therefore it is in some degree probable that the complete or partial blackness of both sexes in such birds as crows, certain cockatoos, storks, and swans, and many marine birds, is likewise the result of sexual selection, accompanied by equal transmission to both sexes; for blackness can hardly serve in any case as a protection. With several birds, in which the male alone is black, and in others in which both sexes are black, the beak or skin about the head is brightly coloured, and the contrast thus afforded adds greatly to their beauty; we see this in the bright yellow beak of the male blackbird, in the crimson skin over the eyes of the black-cock and capercailzie, in the variously and brightly-coloured beak of the Scoter-drake (Oidemia), in the red beak of the chough (_Corvus graculus_, Linn.), of the black swan, and black stork. This leads me to remark that it is not at all incredible that toucans may owe the enormous size of their beaks to sexual selection, for the sake of displaying the diversified and vivid stripes of colour, with which these organs are ornamented.[280] The naked skin at the base of the beak and round the eyes is likewise often brilliantly coloured; and Mr. Gould, in speaking of one species,[281] says that the colours of the beak “are doubtless in the finest and most brilliant state during the time of pairing.” There is no greater improbability in toucans being encumbered with immense beaks, though rendered as light as possible by their cancellated structure, for an object falsely appearing to us unimportant, namely, the display of fine colours, than that the male Argus pheasant and some other birds should be encumbered with plumes so long as to impede their flight.