522 THE DESCENT OF MAN 



CHAPTEE XIV 



BIRDS — continued 



Choice exerted by the female — Length of courtship — Unpaired birds — 

 Mental qualities and taste for the beautiful — Preference or antipathy 

 shown by the female for particular males — Variability of birds — 

 Variations sometimes abrupt — Laws of variation — Formation of ocelli 

 — Gradations of character — Case of Peacock, Argus pheasant, and 

 Urosticte 



WHEN" the sexes difEer in beauty, or in the power 

 of singing, or in producing what I have called 

 instriimental music, it is almost invariably the 

 male who surpasses the female. These qualities, as we 

 have just seen, are evidently of high importance to the 

 male. When they are gained for only a part of the year 

 it is always before the breeding season. It is the male 

 alone who elaborately displays his varied attractions, and 

 often performs strange antics on the ground or in the air, 

 in the presence of the female. Each male drives away, or, 

 if he can, kills his rivals. Hence we may conclude that it 

 is the object of the male to induce the female to pair with 

 him, and for this purpose he tries to excite or charm her 

 in various ways; and this is the opinion of all those who 

 have carefully studied the habits of living birds. But there 

 remains a question which has an all-important bearing oa 

 sexual selection, namely, Does every male of the same 

 species excite and' attract the female equally ? Or does 

 she exert a choice, and prefer certain males? This latter 

 question can be answered in the affirmative by much direct 

 and indirect evidence. It is far more difficult to decide 

 what qualities determine the choice of the females; but 

 here again we have some direct and indirect evidence that 



