256 A THEORY OF BIRDS NESTS. 



hues of the head and back, together with the yellow 

 of the wings and tail, are tints that exactly harmonize 

 with the colours of various species of lichens, while 

 the brilliant red wax tips exactly represent the crimson 

 fructification of tho common lichen, Cladonia cocci- 

 fera. When sitting on its nest, therefore, the female 

 bird will exhibit no colours that are not common 

 to the materials of which it is constructed ; and the 

 several tints are distributed in about the same pro- 

 portions as they occur in nature. At a short distance 

 the bird would be indistinguishable from the nest it is 

 sitting on, or from a natural clump of lichens, and 

 will thus be completely protected. 



I think I have now noticed all exceptions of any 

 importance to the law of dependence of sexual colour 

 on nidification. It will be seen that they are very 

 few in number, compared with those which support 

 the generalization ; and in several cases there are 

 circumstances in the habits or structure of the species 

 that sufficiently explain them. It is remarkable also 

 that I have found scarcely any positive exceptions, 

 that is, cases of very brilliant or conspicuous female 

 birds in which the nest was not concealed. Much less 

 can there be shown any group of birds, in which the 

 females are all of decidedly conspicuous colours on 

 the upper surface, and yet sit in open nests. The 

 many cases in which birds of dull colours in both 

 sexes make domed or concealed nests, do not, of course, 

 affect this theory one way or the other ; since its 

 purpose is only to account for the fact, that brilliant 



