BIRDS-CONSPICUOUS COLORS. 487 



rfcoter-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 colored, and the contrast thus afforded 

 adds much 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 brightly and variously col- 

 ored beak of the scoter-drake (Oidemia), in the red beak of the 

 chough (Corvus graculus, Linn.), of the black swan, and the 

 black stork. This leads me to remark that it is not 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." The 

 naked skin, also, at the base of the beak and round the eyes is 

 likewise often brilliantly colored; and Mr. Gould, in speaking of 

 one species,'" says that the colors of the beak "are doubtless in 

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

 There is no greater improbability that toucans should be encum- 

 bered with immense beaks, though rendered as light as possible 

 by their cancellated structure, for the display of fine colors (an 

 object falsely appearing to us unimportant), than that the male 

 Argus pheasant and some other birds should be encumbered with 

 plumes so long as to impede their flight. 



In the same manner, as the males alone of various species are 

 black, the females being dull-colored; so in a few cases the 



=1 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. il. 1863, p. 341) states that 

 they use their beaks 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 intelli- 

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

 Mr. Belt believes ('The Naturalist in Nicaragua,' p. 197), that the prin- 

 cipal use of the beak is as a defense against enemies, especially to the 

 female whilst nesting in a. hole In a tree. 



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



