The Making of Species 



act of pairing seems to tell against the theory of 

 sexual selection, or at any rate to indicate the 

 purely mechanical nature of the performance. 

 Finn has witnessed this post-nuptial display 

 at the Zoological Gardens (London) in the 

 pied wagtail, the peacock, the Andaman Teal 

 (Nettium albigulare), the Avocet, the Egyptian 

 Goose (Chenatopex <zgyptiaca\ and the Maned 

 Goose (Chenonetta jubata). 



Another objection to the theory that the bright 

 colours of cock birds are due to feminine selection 

 is presented by those birds which breed in im- 

 mature plumage. Darwin admits that this objec- 

 tion would be a valid one " if the younger and 

 less ornamental males were as successful in 

 winning females and propagating their kind as 

 the older and more beautiful males. But," he 

 continues, " we have no reason to suppose that 

 this is the case." 



Unfortunately for the theory of sexual selection, 

 there is evidence to show that the cock Paradise 

 Fly-catcher ( Terpsiphone parodist) in immature 

 plumage is quite as successful in obtaining a 

 mate as is the cock in his final plumage. The 

 cock of this beautiful species has a chestnut 

 plumage in his second year, and a white one 

 in the third and subsequent years of his life. 

 Nevertheless, a considerable proportion of the 

 nests found belong to chestnut cocks. 



Darwin was of opinion that any novelty in 



