If we look to the birds of England we shall see that there is no close and general relation between the colours of the female and the nature of the nest constructed by her. About forty of our British birds (excluding those of large size which could defend themselves) build in holes in banks, rocks, or trees, or construct domed nests. If we take the colours of the female goldfinch, bullfinch, or blackbird, as a standard of the degree of conspicuousness, which is not highly dangerous to the sitting female, then out of the above forty birds, the females of only twelve can be considered as conspicuous to a dangerous degree, the remaining twenty-eight being inconspicuous.[214] Nor is there any close relation between a well-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 (_Muscicapa grisola_) can hardly be distinguished, whilst the sexes of the pied fly-catcher (_M. luctuosa_) 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 nests, in equally well-concealed spots, but in the one species the sexes differ greatly, and in the other very little.