Chap; VIII. SEXUAL SELECTION. 259 



are eminently variable. In the same manner as man 

 can give beauly, according to his standard of taste, to his 

 male poultry — can give to the Sebright bantam a new 

 and elegant plumage, an erect and peculiar carriage — 

 so it appears that in a state of nature female birds, by 

 having long selected the more attractive males, have 

 added to their beauty. No doubt this implies powers 

 of discrimination and taste on the part of the female 

 which will at first appear extremely improbable; but 

 I hope hereafter to shew that this is not the case. 



From our ignorance on several points, the precise 

 manner in which sexual selection acts is to a certain 

 extent uncertain. Nevertheless if those naturalists who 

 already believe in the mutability of species, will read 

 the following chapters, they will, I think, agree with 

 me that sexual selection has played an important part 

 in the history of the organic world. It is certain that 

 with almost all animals there is a struggle between the 

 males for the possession of the female. This fact is so 

 notorious that it would be superfluous to give instances. 

 Hence the females, supposing that their mental capacity 

 sufficed for the exertion of a choice, could select. one out 

 of several males. But in numerous cases it appears as 

 if it had been specially arranged that there should be 

 a struggle between many males. Thus with migratory 

 birds, the males generally arrive before the females at 

 their place of breeding, so that many males are ready 

 to contend for each female. The bird-catchers assert 

 that this is invariably the case with the nightingale and 

 blackcap, as I am informed by Mr. ^Tenner Weir, who 

 confirms the statement with respect to the latter species. 



Mr. Swayslancl of Brighton, who has been in the habit, 

 during the last forty years, of catching our migratory 

 birds on their first arrival, writes to me that he has 

 never known the females of any species to arrive before 



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