Chap. XVI. CONSPICUOUS COLOURS. 227 



for blackness can hardly serve in any case as a pro- 

 tection. 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 (Gorvus 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 selec- 

 tion, for the sake of displaying the diversified and vivid 

 stripes of colour, with which these organs are orna- 

 mented.^^ 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,^^ 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 



^2 No satisfactory explanation has ever been offered of the immense 

 size, and still less of the bright colours, of the toucan's beak. Mr. 

 Bates (• The Naturalist on the Amazons,' "Vol. ii. 1863, p. 341) states 

 that they use their beak for reaching fruit at the extreme tips of the 

 branches ; and likewise, as stated by other authors, for extracting eggs 

 and young birds from the nests of other birds. But as Mr. Bates admits, 

 the beak " can scarcely be considered a very perfectly-formed instru- 

 " raent for the end to which it is applied." The great bulk of the beak, 

 as shewn by its breadth, depth, as well as length, is not intelligible on 

 the view, that it serves merely as an organ of prehension. 



•" Kamphastos carinatus, Gould's ' Monograph of Eamphastidse.' 



Q 2 



