170 SEXUAL selection: BIEDS. PartIL 



as conspicuous to a dangerous degree, the remaining 

 twenty-eight being inconspicuous.^^ Nor is there any 

 close relation between a Avell-pronounced difference in 

 colour between the two 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) differs hardly at all, and yet 

 both build well-concealed nests. The two sexes of the 

 common fly-catcher (Muscicajpa grisola) can hardly be 

 distinguished, whilst the sexes of the pied fly-catcher 

 {M. luduosa) differ considerably, and both build in holes. 

 The female blackbird (Turdus merula) differs much, 

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

 and the female common thrush (T. musicus) hardly 

 at all from their respective males ; yet all build open 

 nests. On the other hand, the not very distantly- 

 allied water-ouzel {Cinclus aquaticus) builds a domed 

 nest, and the sexes differ about as much as in the case 

 of the ring-ouzel. The black and red grouse (Tetrao 

 tetrix and T. Scoticus) build open nestSj 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, 



^^ I have consulted, on this subject, Macgillivray's ' British Birds,' 

 and though doubts may be entertained in some cases in regard to the 

 degree of concealment of the nest, and of the degree of conspicuousness 

 of the female, yet the following birds, which all lay their eggs in holes 

 or in domed nests, can hardly be considered, according to the above 

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

 female is considerably less brilliant than the male ; Cinclus ; Motacilla 

 boarula (?) ; Erithaeus (?) ; Fruticola, 2 sp. ; Saxicola ; Euticilla, 2 

 sp. ; Sylvia, 3 sp. ; Parus, 3 sp. ; Mecistura ; Anorthura ; Certhia ; 

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

 females of the following 12 birds may be considered as conspicuous 

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

 major and P. cseruleus, Upupa, Picus, 4 sp., Coracias, Alcedo, and Merops. 



