BIRDS-COLOR AND NIDIFICATION. 449 



tion within the same genus between a well-pronounced difference 

 in color between the sexes, and the nature of the nest constructed. 

 Thus the male house sparrow (Passer domesticus) differs much 

 from the female, the male tree-sparrow (P. montanus) hardly at 

 all, and yet both build well-concealed nests. The two sexes of the 

 common fly-catcher (Musicapse grisola) can hardly be distin- 

 guished, whilst the sexes of the pied fly-catcher (M. luctuosa) dif- 

 fer considerably, and both species build in holes or conceal their 

 nests. The female blackbird (Turdus merula) differs much, the 

 female ring-ouzel (T. torquatus) differs less, and the female com- 

 mon thrush (T. musicus) hardly at all from their respective males; 

 yet all build open nests. On the other hand, the not very dis- 

 tantly-allied water-ouzel (Cinolus aquaticus) builds a domed nest, 

 and the sexes differ about as much as in the ring-ouzel. The 

 black and red grouse (Tetrao tetrix and T. scoticus) build open 

 nests in equally well-concealed spots, but in the one species the 

 sexes differ greatly, and in the other very little. 



Notwithstanding the foregoing objections, I cannot doubt, after 

 reading Mr. Wallace's excellent essay, that looking to the birds 

 of the world, a large majority of the species in which the females 

 are conspicuously colored (and in this case the males with rare 

 exceptions are equally conspicuous), build concealed nests for 

 the sake of protection. Mr. Wallace enumerates™ a long series 

 of groups in which this rule holds good; but it will sufl5ce here 

 to give, for instance, the more familiar groups of kingfishers, 

 toucans, trogons, puff -birds (Capitcnidae), plantain-eaters (Mu- 

 sophagae), woodpeckers, and parrots. Mr. Wallace believes that 

 in these groups, as the males gradually acquired through sexual 

 selection their brilliant colors, these were transferred to the fe- 

 males and were not eliminated by natural selection, owing to 

 the protection which they already enjoyed from their manner of 

 nidification. According to this view, their present manner of 

 nesting was acquired before their present colors. But it seems to 

 me much more probable that in most cases, as the females were 

 gradually rendered more and more brilliant from partaking of 

 the colors of the male, they were gradually led to change their in- 

 stincts (supposing that they originally built open nests), and to 



the above standard, as conspicuous: Passer, 2 species; Sturnus, of 

 which the female is considerably less brilliant than the male; Cinolus; 

 Motaoilla boarula (?); Erithacus (?); Fruticola, 2 sp.; Saxicola; Ruti- 

 cilla, 2 sp.; Sylvia, 3 sp. ; Parus, 3 sp. ; Mecistura; Anorthura; Cer- 

 thia; Sitta; Yunx; Muscicapa, 2 sp. ; Hirundo, 3 sp. ; and Cypselus. 

 The females of the following; 12 birds may be considered as conspicu- 

 ous, according to the same standard, viz., Pastor, Motacilla alba, 

 Parus major and P. caeruleus, Upupa, Picus, 4 sp., Coracias, Alcedo, 

 and Merops. 

 " 'Journal of Travel," edited by A. Murray, vol. i. p. 78. 

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