182 NATURAL SELECTION vi 



of my views of the general theory of protective adaptation. 

 Yet it is undoubtedly the fact that in the best known cases 

 in which the female bird is more conspicuously coloured than 

 the male, it is either positively ascertained that the latter 

 performs the duties of incubation, or there are good reasons 

 for believing such to be the case. The most satisfactory 

 example is that of the Gray Phalarope (Phalaropus fulicarius), 

 the sexes of which are alike in winter, while in summer the 

 female instead of the male takes on a gay and conspicuous 

 nuptial plumage ; but the male performs the duties of incubation, 

 sitting upon the eggs, which are laid upon the bare ground. 



In the dotterel! (Eudromias morinellus) the female is 

 larger and more brightly coloured than the male ; and here, 

 also, it is almost certain that the latter sits upon the eggs. 

 The turnices of India also have the female larger and often 

 more brightly coloured ; and Mr. Jerdon states, in his Birds 

 of India, that the natives report that, during the breeding 

 season, the females desert their eggs and associate in flocks, 

 while the males are employed in hatching the eggs. In the 

 few other cases in which the females are more brightly 

 coloured, the habits are not accurately known. The case of 

 the ostriches and emeus will occur to many as a difficulty, 

 for here the male incubates, but is not less conspicuous than 

 the female ; but there are two reasons why the case does not 

 apply : the birds are too large to derive any safety from 

 concealment ; from enemies which would devour the eggs 

 they can defend themselves by force, while to escape from 

 their personal foes they trust to speed. 



We find, therefore, that a very large mass of facts relating 

 to the sexual coloration and the mode of nidification of birds, 

 including some of the most extraordinary anomalies to be 

 found in their natural history, can be shown to have an inter- 

 dependent relation to each other, on the simple principle of 

 the need of greater protection to that parent which performs 

 the duties of incubation. Considering the very imperfect 

 knowledge we possess of the habits of most extra-European 

 birds, the exceptions to the prevalent rule are few, and gene- 

 rally occur in isolated species or in small groups ; while several 

 apparent exceptions can be shown to be really confirmations 

 of the law. 



