154 SEXUAL SELECTION : BIRDS. Part IL 



CHAPTER XV. 



Birds — continued. 



Discussion wliy the males alone of some species, and both sexes of 

 other species, are brightly coloured — On sexually-limited in- 

 heritance, as applied to various structures and to brightly- 

 coloured plumage — Nidification in relation to colour — Loss of 

 nuptial plumage during the winter. 



We have in this chapter to consider, wh}^ with many 

 kinds of birds the female has not received the same 

 ornaments as the male ; and why with many others, 

 both sexes are equally, or almost equally, ornamented ? 

 In the following chapter we shall consider why in some 

 few rare cases the female is more conspicuously coloured 

 than the male. 



In my ' Origin of Species ' ^ I briefly suggested that 

 the long tail of the peacock would be inconvenient, and 

 the conspicuous black colour of the male capercailzie 

 dangerous, to the female during the period of incubation ; 

 and consequently that the transmission of these charac- 

 ters from the male to the female offspring had been 

 checked through natural selection. I still think that 

 this mav have occurred in some few instances : but after 

 mature reflection on all the facts which I have been 

 able to collect, I am now inclined to believe that 

 wlien the sexes differ, the successive variations have 

 generally been from the first limited in their transmis- 

 sion to the same sex in which they first appeared. Since 

 my remarks appeared, the subject of sexual coloration 



* Fourth edition, 1806, p. 241. 



