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 (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 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 
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. 311) 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- 
‘‘ ment 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. 
Ramphaston carinatus, Gould’s ‘ Monograph of Ramphastidae.’ 
Q 2 
