84 SEXUAL SELECTION: BIRDS. Part IL 



dered more and more complete, until a perfect double 

 moult was acquired. A gradation can also be shewn to 

 exist in the length of time during which either 

 annual plumage is retained; so that the one might 

 come to be retained for the whole year, the other being 

 completely lost. Thus the Machetes pugnax retains 

 his ruff in the spring for barely two months. The 

 male widow-bird ( Chera j)rc(/ne) acquires in Natal his 

 fine plumage and long tail-feathers in December or 

 January and loses them in March ; so that they are 

 retained during only about three months. Most species 

 which undergo a double moult keep their ornamental 

 feathers for about six months. The male, however, of 

 the wild Gallus ha^iJciva retains his neck-hackles for 

 nine or ten months ; and when these are cast off, the 

 underlying black feathers on the neck are fully exposed 

 to view. But with the domesticated descendant of this 

 species, the neck-hackles of the male are immediately 

 replaced by new ones ; so that we here see, with respect 

 to part of the plumage, a double moult changed under 

 domestication into a sinole moult." 



The common drake (Anas hoschas) is well know n after 

 the breeding-season to lose his male plumage for a 

 period of three months, during which time he assumes 

 that of the female. The male pintail-duck (Anas 

 acuta) loses his plumage for the shorter period of 

 six weeks or two months ; and Montasfu remarks that 



'7 For the foregoing statements in regard to partial moults, and on 

 old males retaining their nuptial plumage, see Jerdon, on bustards and 

 plovers, in ' Birds of India,' vol. iii. p. 617, 637, 709, 711. Also Blyth 

 in ' Land and Water,' 1867, p. 84. On 'the Vidua, ' Ibis,' vol. iii. 1861, 

 p. 133. On the Drongo shrikes, Jerdon, ibid. vol. i. p. 435. On the 

 vernal moult of the Herodias buhulcus, Mr, S. S. Allen, in ' Ibis,' 1863, 

 p. 33. On Gallus hanlciva, Blyth, in ' Annals and Mag. of Nat. Hist.' 

 vol. i. 1848, p. 455 ; see, also, on this subject, my ' Variation of Animals 

 under Domestication,' vol. i. p. 236. 



