coloured (and in this case the males with rare exceptions are equally
conspicuous), build concealed nests for the sake of protection. Mr.
Wallace enumerates (19. Journal of Travel, edited by A. Murray, vol.
i. p. 78.) a long series of groups in which this rule holds good; but
it will suffice here to give, as instances, the more familiar groups of
kingfishers, toucans, trogons, puff-birds (Capitonidae),
plantain-eaters (Musophagae, woodpeckers, and parrots. Mr. Wallace
believes that in these groups, as the males gradually acquired through
sexual selection their brilliant colours, these were transferred to the
females and were not eliminated by natural selection, owing to the
protection which they already enjoyed from their manner of
nidification. According to this view, their present manner of nesting
was acquired before their present colours. But it seems to me much more
probable that in most cases, as the females were gradually rendered
more and more brilliant from partaking of the colours of the male, they
were gradually led to change their instincts (supposing that they
originally built open nests), and to seek protection by building domed
or concealed nests. No one who studies, for instance, Audubon s account
of the differences in the nests of the same species in the Northern and
Southern United States (20. See many statements in the Ornithological
Biography. See also some curious observations on the nests of Italian
birds by Eugenio Bettoni, in the Atti della Societa Italiana, vol.
xi. 1869, p. 487.), will feel any great difficulty in admitting that
birds, either by a change (in the strict sense of the word) of their
habits, or through the natural selection of so-called spontaneous
variations of instinct, might readily be led to modify their manner of
nesting.
This way of viewing the relation, as far as it holds good, between the
bright colours of female birds and their manner of nesting, receives
some support from certain cases occurring in the Sahara Desert. Here,
as in most other deserts, various birds, and many other animals, have
had their colours adapted in a wonderful manner to the tints of the
surrounding surface. Nevertheless there are, as I am informed by the
Rev. Mr. Tristram, some curious exceptions to the rule; thus the male
of the Monticola cyanea is conspicuous from his bright blue colour, and
the female almost equally conspicuous from her mottled brown and white
plumage; both sexes of two species of Dromolaea are of a lustrous
black; so that these three species are far from receiving protection
from their colours, yet they are able to survive, for they have
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