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Show 194 SEXUAL SELECTION: BIRDS. PART II. differ from each other chiefly in the points in which they partially resemble their respective .males ; and the colours of the males may safely be attnb~ted to sexual selection. With many gallinaceous speCies the sexes differ to an extreme degree, as with the peacock, pheasant and fowl, whilst with other species there has been a partial or even complete transference of character from the male to the female. The females of th.e. several species of Polyplectron exhibit. in a di.m cond1~10n, and chiefly on the tail, the splendid ocelli of their :nales. The female partridge differs from the male only m the red mark on her breast being smaller ; and the female wild turkey only in her colours being much duller. In the guinea-fowl the two sexes are ~ndistinguishable. There is no improbability in the pla~.n, thou?h peculiar spotted plumage of this latter bu·d havmg been acquired through sexual selection by . th~ males, and then transmitted to both sexes ; for It IS not essentially different from the much more beautifully-sp~tted plumage, characteristic of the males alone of the rragopan pheasants. It should be observed that, in some instances, the transference of characters from the male to the female has been effected apparently at a remote period, the male havino- subsequently undergone great changes, without tm~sferring to the female any of his latergained characters. For instance, the fe~ale and the young of the black-grouse (Tetrao tetnx) resemble pretty closely both sexes and the young of the .redgrouse T. Scoticus; and we may consequently I~fer that the black-o-rouse is descended from some ancient 0 species, of which both sexes were co 1o ure d m. near l Y the same manner as the red-grouse. As both sexes of this latter species are more plainly barred during the br~eding-season than at any other time, and as the male CHAP. XVI. THE YOUNG LIKE THE ADULT FEMALES. 195 differs slightly from the female in his more stronglypronounced red and brown tints/0 we may conclude that his plumage has been, at least to a certain extent, influenced by sexual selection. If so, we may further infer that the nearly similar plumage of the female black-grouse was similarly produced at some former period. But since this period the male black-grouse has acquired his fine black plumage, with his forked and outwardly-curled tail-feathers; but of these characters there bas hardly been any transference to the female, excepting that she shews in her tail a trace of the curved fork. We may therefore conclude that the females of distinct though allied species have often had their plumage rendered more or less different by the transference in various degrees, of characters acquired, both during former and recent times, by the males through sexual selection. But it deserves especial attention that brilliant colours have been transferred much more rarely than other tints. For instance, the male of the red-throated bluebreast (Cyanecula sueoioa) has a rich blue breast, including a sub-triangular red mark; now marks of approximately the Rame shape have been transferred to the female, but the central space is fulvous instead of red, and is surrounded by mottled instead of blue feathers. The Gallinacere offer many analogous cases ; for none of the species, such as partridges, quails, guinea-fowls, &c., in which the colours of the plumage have been largely transferred from the male to the female, are brilliantly coloured. This is well exemplified with the pheasants, in which the male is generally so much more brilliant than the female; but with the Eared and Cheer pheasants (Crossoptilon 10 Macgillivray, 'Hist. British Birds,' vol. i. p. 172-174. 0 2 |