Chap. XV.] COLOR AND NIDIFICATION. 159 



the bright tints, originally acquired through sexual selec- 

 tion by the males, would in all or almost all cases have 

 been transmitted to the females,, unless the transference 

 had been checked through natural selection. I may here 

 remind the reader that various facts bearing on this view 

 have already been given under reptiles, amphibians, 

 fishes, and lepidoptera. Mr. Wallace rests his belief 

 chiefly, but not exclusively, as we shall see in the next 

 chapter, on the following statement, 8 that when both sexes 

 are colored in a strikingly-conspicuous manner the nest is 

 of such a nature as to conceal the sitting bird ; but when 

 there is a marked contrast of color between the sexes, the 

 male being gay and the female dull colored, the nest is 

 open and exposes the sitting bird to view. This coinci- 

 dence, 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 excep- 

 tions 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, 9 that a large-domed nest is more con- 

 spicuous to an enemy, especially to all tree-haunting car- 

 nivorous animals, than a smaller open nest. Nor must 

 we forget, that wjth 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 instance, with 

 Pyranga cestiva, 10 one of the most splendid birds in the 

 United States, the male being vermilion, and the female 

 light brownish-green. Now, if brilliant colors had been 

 extremely dangerous to birds while sitting on their open 



8 « Journal of Travel,' edited by A. Murray, vol. i. 18GS, p. 18. 



9 Ibid. p. 281. 



10 Audubon, ' Ornithological Biography,' vol. i. p. 233. 



