Chap. XV. COLOUR AND NIDIFICATION. 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 Fijranga sestiva^^ 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 Kiiig-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- 



9 ' Journal of Travel,' edited by A. Murray, vol. i. 18G8, p. 281. 

 *<' Audubon, ' Ornithological Biography,' vol. i. p. 2i?3. 



