Alfred Russel Wallace 



to certain female birds being more brightly coloured than 

 the males, and the latter incubating, I have gone a little 

 into the subject and cannot say that I am fully satisfied. 

 1 remember mentioning to you the case of Khynchaea, but 

 its nesting seems unknown. In some other cases the 

 difference in brightness seemed to me hardly sufficiently 

 accounted for by the principle of protection. At the 

 Falkland Islands there is a carrion hawk in which the 

 female (as I ascertained by dissection) is the brightest 

 coloured, and I doubt whether protection will here apply; 

 but I wrote several months ago to the Falklands to make 

 inquiries. The conclusion to which I have been leaning is 

 that in some of these abnormal cases the colour happened 

 to vary in the female alone, and was transmitted to females 

 alone, and that her variations have been selected through the 

 admiration of the male. 



It is a very interesting subject, but I shall not be able 

 to go on with it for the next five or six months, as I am 

 fully employed in correcting dull proof-sheets; when I 

 return to the work I shall find it much better done by you 

 than I could have succeeded in doing. 



With many thanks for your very interesting note, believe 

 me, dear Wallace, yours very sincerely, qjj^ Darwin. 



It is curious how we hit on the same ideas. I have 

 endeavoured to show in my MS. discussion that nearly the 

 same principles account for young birds not being gaily 

 coloured in many cases — but this is too complex a point for 

 a note. 



more brightly coloured than the male and has a convoluted trachea, elsewhere 

 a masculine character. There seems some reason to suppose that " the male 

 undertakes the duty of incubation." 



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