The Descent of Man

they would have been much more conspicuous
to their enemies; but whether their dull tints
have been specially gained for the sake of protection
seems, as far as I can judge, rather
doubtful. It is still more doubtful whether such
dull tints can have been gained for the sake of
ornament. We must, however, bear in mind
that male birds, though dull-coloured, often
differ much from their females (as with the
common sparrow), and this leads to the belief
that such colours have been gained through
sexual selection, from being attractive. Many of
the soft-billed birds are songsters; and a discussion
in a former chapter should not be forgotten,
in which it was shewn that the best songsters
are rarely ornamented with bright tints. It
would appear that female birds, as a general
rule, have selected their mates either for their
sweet voices or gay colours, but not for both
charms combined. Some species, which are
manifestly coloured for the sake of protection,
such as the jack-snipe, woodcock, and night-jar,