Chap. XVI.] CONSPICUOUS COLORS. 217 



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 colored, 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 colored 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 color with which these 

 organs are ornamented. 62 The naked skin at the base of 

 the beak and round the eyes is likewise often brilliantly 

 colored ; and Mr. Gould, in speaking of one species, 53 says 

 that the colors of the beak " are doubtless in the finest 

 and most brilliant state during the the time of pairing." 

 There is no greater improbability in toucans being encum- 

 bered with immense beaks, though rendered as light as 

 possible by their cancellated structure, for an object false- 

 ly appearing to us unimportant, namely, the display of 

 fine colors, than that the male Argus pheasant and some 



62 No satisfactory explanation has ever been offered of the immense 

 size, and still less of the bright colors, 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 instrument for the 

 end to which it is applied." The great bulk of the beak, as shown by 

 its breadth, depth, as well as length, is not intelligible on the view that 

 t serves merely as an orgau of prehension. 



** Ramphastos carinatus, Gould's ' Monograph of Ramphastidae.' 



29 



