Chap. XIV. 
SEXUAL selection: birds, 
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CHAPTEE XIV. 
Birds — continued. 
Choice exerted by the female — Length of courtship — Unpaired 
birds — Mental qualities and taste for the beautiful — Preference 
or antipathy shewn by the female for particular males — Yari- 
ability of birds — Variations sometimes abrupt — Laws of varia- 
tion — Formation of ocelli — Gradations of character — Case of 
Peacock, Argus pheasant, and Urosticte. 
When the sexes differ in beauty, in the power of 
singing, or in producing what I have called instru- 
mental music, it is almost invariably the male which, 
excels 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, this 
is always shortly before the breeding-season. It is the 
male alone who elaborately displays his varied attrac- 
tions, 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 all 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 equally excite and attract the female ? or 
does she exert a choice, and prefer certain males ? This 
question can be answered in the affirmative by much 
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