Contributions to the theory of natural selection. A series of essays ... By Alfred Russel Wallace ...

A THEORY OF BIRDS' NESTS. 253
Real or apparent Exceptions to the Law stated at
page 240.
The only marked exceptions I have been able to
discover are the following:1. King crows (Dicrourus). These birds are of a
glossy black colour with long forked tails. The sexes
present no difference, and they build open nests. This
apparent exception may probably be accounted for by
the fact that these birds do not need the protection
of a less conspicuous colour. They are very pugnacious, and often attack and drive away crows, hawks,
and kites; and as they are semi-gregarious in their
habits, the females are not likely to be attacked while
incubating.
2. Orioles (Oriolidm). The true orioles are very gay
birds; the sexes are, in many Eastern species, either
nearly or quite alike, and the nests are open. This
is one of the most serious exceptions, but it is one
that to some extent proves the rule; for in this case
it has been noticed, that the parent birds display
excessive care and solicitude in concealing the nest
among thick foliage, and in protecting their offspring
by incessant and anxious watching. This indicates
that the want of protection consequent on the bright
colour of the female makes itself felt, and is obviated
by an increased development of the mental faculties.
3. Ground thrushes (Pittidae). These elegant and
brilliantly-coloured birds are generally alike in both
sexes, and build an open nest. It is curious, however,