684 THE DESCENT OF MAN 



nous females have acquired the instinct of building domed 

 nests oftener than dull-colored birds. 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" 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 with many birds which build open nests the male 

 sits on the eggs and aids the female in feeding the young: 

 this is the case, for instance, with Pyranga cestiva," 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 nests, the males in these 

 cases would have suffered greatly. It might, however, be 

 of such paramount importance to the male to be brilliantly 

 colored, in order to beat his rivals, that this may have mors 

 than compensated some additional danger. 



Mr. Wallace admits that with the King-crows (Dicrurus), 

 Orioles, and Pittidee, the females are conspicuously colored, 

 yet build open nests; but he urges that the birds of the 

 first group are highly pugnacious and could defend them- 

 selves; that those of the second group take extreme care 

 in concealing their open nests, but this does not invariably 

 hold good;" and that with the birds of the third group the 

 females are brightly colored chiefly on the under surface. 

 Besides these cases, pigeons, which are sometimes brightly 

 and almost always conspicuously colored, and which are 

 notoriously liable to the attacks of birds of prey, offer a 

 serious exception to the rule, for they almost always build 



"> "Journal of Travel," edited by A. Murray, vol. I., 1868, p. 281. 

 " Audubon, "Ornithological Biography," vol. i. p. 233. 

 '* Jerdon, "Birds of India," voL ii. p. 108. Gould's "Handbook of the 

 Birds of Australia," vol. i. p. 463. 



