The Descent of Man

contrast of colour between the sexes, the male
being gay and the female dull-coloured, the
nest is open and exposes the sitting bird to
view. This coincidence, as far as it goes, certainly
seems to favour the belief that the females
which sit on open nests have been specially
modified for the sake of protection; but we
shall presently see that there is another and
more probable explanation, namely, that conspicuous
females have acquired the instinct of
building domed nests oftener than dull- coloured
birds. Mr. Wallace admits that there are, as
might have been expected, some exceptions to
his two rules, but it is a question whether the
exceptions are not so numerous as seriously to
invalidate them.
There is in the first place much truth in the Duke
of Argyll's remark (10. 'Journal of Travel,'
edited by A. Murray, vol. i. 1868, p. 281.) that a
large domed nest is more conspicuous to an
enemy, especially to all tree- haunting carnivo-