Chap. XVI. THE YOUNG LIKE THE ADULT MALES. 207 
rendered less conspicuous for the sake of protection 
during the period of incubation ; but the difference 
between the sexes in hardly any of the foregoing cases 
appears sufficiently great for this view to be safely ac- 
cepted. In some of the cases the brighter tints of the 
female are almost confined to the lower surface, and the 
males, if thus coloured, would not have been exposed to 
danger whilst sitting on the eggs. It should also be 
borne in mind that the males are not only in a slight 
degree less conspicuously coloured than the females, but 
are of less size, and have less strength. They have, more- 
over, not only acquired the maternal instinct of incuba- 
tion, but are less pugnacious and vociferous than the 
females, and in one instance have simpler vocal organs. 
Thus an almost complete transposition of the instincts, 
habits, disposition, colour, size, and of some points of 
structure, has been effected between the two sexes. 
Now if we might assume that the males in the present 
class have lost some of that ardour which is usual to 
their sex, so that they no longer search eagerly for the 
females ; or, if we might assume that the females have 
become much more numerous than the males — and in 
the case of one Indian Turnix the females are said to be 
much more commonly met with than the males ” — 
then it is not improbable that the females would have 
been led to court the males, instead of being courted by 
them. This indeed is the case to a certain extent, with 
some birds, as we have seen with the peahen, wild turkey, 
and certain kinds of grouse. Taking as our guide the 
habits of most male birds, the greater size and strength 
and the extraordinary pugnacity of the females of the 
Turnix and Emu, must mean that they endeavour to 
drive away rival females, in order to gain possession of 
26 Jerdon, ‘ Birds of India/ vol. iii. p. 598. 
