Chap. IV. SEXUAL SELECTION. 89 



believe that there is the severest rivalry between the 

 males of many species to attract by singing the females. 

 The rock-thrush of Guiana, birds of Paradise, and some 

 others, congregate ; and successive males display their 

 gorgeous plumage and perform strange antics before the 

 females, winch standing by as spectators, at last choose 

 the most attractive partner. Those who have closely 

 attended to birds in confinement well know that they 

 often take individual preferences and dislikes : thus 

 Sir R. Heron has described how one pied peacock was 

 eminently attractive to all his hen birds. It may 

 appear childish to attribute any effect to such appa- 

 rently weak means : I cannot here enter on the details 

 necessary to support this view ; but if man can in a short 

 time give elegant carriage and beauty to his bantams, 

 according to his standard of beauty, I can see no good 

 reason to doubt that female birds, by selecting, during 

 thousands of generations, the most melodious or beautiful 

 males, according to their standard of beauty, might pro- 

 duce a marked effect. I strongly suspect that some 

 well-known laws with respect to the plumage of male 

 and female birds, in comparison with the plumage of the 

 young, can be explained on the view of plumage having 

 been chiefly modified by sexual selection, acting when 

 the birds have come to the breeding age or during the 

 breeding season ; the modifications thus produced being 

 inherited at corresponding ages or seasons, either by 

 the males alone, or by the males and females ; but I 

 have not space here to enter on this subject. 



Thus it is, as I believe, that when the males and 

 females of any animal have the same general habits 

 of life, but differ in structure, colour, or ornament, 

 such differences have been mainly caused by sexual 

 selection ; that is, individual males have had, in suc- 

 cessive generations, some slight advantage over other 



