BIRDS. ' 459 



CHAPTER XIV. 



BIEDS 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. 



the sexes differ in beauty or in the power of sing- 

 ing, or in producing what I have called instrumental 

 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 on 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 it is to a large extent the external 

 attractions of the male; though no doubt his vigor, cour- 

 age, and other mental qualities come into play. We will 

 begin with the indirect evidence. 



