138 THE ZOOLOGIST. 



The second generalisation which the egg-collector is likely to 

 make is the fact that so many of these birds which breed in 

 holes are gorgeously coloured, such as Kingfishers, Parrots, Bee- 

 eaters, &c. The question naturally arises. Why is it so ? The 

 advocates of protective selection reply, Because their gay plumage 

 made them so conspicuous as they sat upon their nests, that 

 that those that did not breed in holes became the victims of the 

 devouring Hawk, exactly as the conspicuous white eggs were 

 eaten by the marauding Magpie. But the advocates of sexual 

 selection say that all birds are equally vain, and wear as fine 

 clothes as Nature will let them, and that the Kingfisher is able 

 to dress as gorgeously as he does because he is prudent enough 

 to breed in a hole safe from the prying eyes of the devouring 

 Hawk. The fact that many birds, such as the Sand Martin and 

 the Dipper, which breed in holes, are not gorgeously coloured, 

 whilst others, such as the Pheasants and Humming-birds, are 

 gorgeously coloured, but do not breed in holes, is evidence, as 

 far as it goes, that the gorgeous colour of the bird is not the 

 effect of its breeding in a hole, though the white colour of the 

 egg probably is. It must be admitted, however, that the latter 

 cases are not parallel. Whilst the hen Kingfishers and Bee- 

 eaters are as gorgeous as their mates, the hen Pheasants and the 

 hen Humming-birds are plainly, not to say shabbily, dressed. If 

 birds be as vain as the advocates of sexual selection deem them, 

 it must be a source of deep mortification to a hen Humming-bird 

 to have to pass through life as a foil to her rainbow-hued mate. 

 Whilst the Kingfisher relies for the safety of its eggs upon the 

 concealed situation of its nest, the Humming-bird depends upon 

 the unobtrusiveness of the plumage of the sitting hen. 



A very large number of birds, such as the Grouse, the Merlin, 

 most Gulls and Terns, and all Sandpipers and Plovers, rely for 

 the safety of their eggs upon the similarity of their colour to the 

 ground on which they are placed. It may be an open question 

 whether these birds select a site for their breeding-ground to 

 match the colour of the eggs, or whether they have gradually 

 changed the colour of their eggs to match the ground on which 

 they breed ; but, in the absence of any evidence to the contrary, 

 it is perhaps fair to assume, as in the previously mentioned 

 cases, that the position of the nest is the cause, and the colour 

 of the egg the effect. 



