latter bird having been acquired through sexual selection by the males,
and then transmitted to both sexes; for it is not essentially different
from the much more beautifully spotted plumage, characteristic of the
males alone of the Tragopan 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 having subsequently undergone great changes,
without transferring to the female any of his later-gained characters.
For instance, the female and the young of the black-grouse (Tetrao
tetrix) resemble pretty closely both sexes and the young of the
red-grouse (T. scoticus); and we may consequently infer that the
black-grouse is descended from some ancient species, of which both
sexes were coloured in nearly the same manner as the red-grouse. As
both sexes of this latter species are more distinctly barred during the
breeding-season than at any other time, and as the male differs
slightly from the female in his more strongly-pronounced red and brown
tints (10. Macgillivray, History of British Birds, vol. i. pp.
172-174.), we may conclude that his plumage has been influenced by
sexual selection, at least to a certain extent. If so, we may further
infer that 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 has
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 by the males
through sexual selection, both during former and recent times. 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 blue-breast (Cyanecula suecica) has a rich blue
breast, including a sub-triangular red mark; now marks of nearly the
same 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 Gallinaceae offer many analogous cases; for none of the
species, such as partridges, quails, guinea-fowls, etc., in which the
colours of the plumage have been largely transferred from the male to
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