Chap. XV. 
COLOUR AND NIDIFICATIOS. 
167 
conspicuous manner the nest is of such a nature as to 
conceal the sitting bird ; but when there is a marked 
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 supports the belief that the 
females which sit on open nests have been specially 
modified for the sake of protection. 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^ that a large domed nest is more 
conspicuous to an enemy, especially to all tree-haunting 
carnivorous animals, than a smaller open nest. Nor 
must we forget that with many birds which build open 
nests the males sit on the eggs and aid in feeding the 
young as well as the females : this is the case, for in- 
stance, with Pyranga aediva^^ one of the most splendid 
birds in the United States, the male being vermilion, 
and the female light brownish-green. Now if brilliant 
colours had been extremely dangerous to birds whilst 
sitting on their open nests, the males in these cases 
would have suffered greatly. It might, however, be of 
such paramount importance to the male to be bril- 
liantly coloured, in order to beat his rivals, that this 
would more than compensate for some additional danger. 
Mr. Wallace admits that with the King-crows (Di- 
crurus). Orioles, and Pittidse, the females are conspi- 
cuously coloured, yet they build open nests ; but he 
urges that the birds of the first group are highly pug- 
^ ‘ Journal of Travel,’ edited by A. Murray, vol. i. 1868, p. 281. 
Audubon, ‘ Ornithological Biography,’ vol. i. p. 288. 
