^ 6 The Colours of Animals. 



the hole of a tree, &c., we find it no longer to be such 

 an invariable rule that the hen bird is dull-coloured ; 

 but, on the contrary, she is then often as gaily- 

 coloured as the male. Such, for instance, is the 

 case with the hen kingfisher, which is one of the 

 brightest of British birds and one of the very few 

 which make their nests underground ; the hen 

 woodpecker, which is also gaily-coloured and builds 

 in hollow trees, forms a second instance. 



In the few cases where the hens are as con- 

 spicuously coloured as the cocks, and yet the nest 

 is open to view, we generally find that the hens 

 are strong, pugnacious birds, and well able to 

 defend themselves. There are even instances, 

 though these are comparatively rare, in which the 

 hens are more brilliantly-coloured than the cocks ; 

 and it is an interesting fact that it is then the cocks, 

 and not the hens, which hatch the eggs. 



4. It therefore seems to be a rule, with very few 

 exceptions, that when both the cocks and hens are 

 of strikingly gay or conspicuous colours, the nest 

 is such as to conceal the sitting bird ; while, when- 

 ever there is a striking contrast of colours, the nest 

 is open and the sitting bird exposed to view. 



Again, most fishes are dark above and pale 

 below. This points to the same fact, for w r hen one 

 looks down into the dark water, the dark colour of 

 their backs renders them the less easy to distin- 

 guish ; while, to an enemy looking up from below, 

 the pale belly would be less conspicuous against 



