0HAP..XT1I. 



Double Annual Moult. 



A. 



393 



that we here see, as to part of the plumage, a double moult 

 changed under domestication into a single moult. 82 



The common drake (Anas boschas) after the breeding- season 

 is well known 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 Montagu remarks that 

 " this double moult within so short a time is a most extra' 

 " ordinary circumstance, that seems to bid defiance to all human 

 " reasoning." But the believer in the gradual modification of 

 species will be far from feeling surprise at finding gradations of 

 all kinds. If the male pintail were to acquire his new plumage 

 within a still shorter period, the new male feathers would 

 almost necessarily be mingled with the old, and both with some 

 proper to the female ; and this apparently is the case with the 

 male of a not distantly-allied bird, namely the Merganser serrator, 

 for the males are said to " undergo a change of plumage, which 

 " assimilates them in some measure to the female." By a little 

 further acceleration in the process, the double moult would be 

 completely lost. 83 



Some male birds, as before stated, become more brightly 

 coloured in the spring, not by a vernal moult, but either by an 

 actual change of colour in the feathers, or by their obscurely- 

 coloured deciduary margins being shed. Changes of colour thus 

 caused may last for a longer or shorter time. In the Pelecanus 

 oiiocrotalas a beautiful rosy tint, with lemon-coloured marks on 

 the breast, overspreads the whole plumage in the spring ; but 

 these tints, as Mr. Sclater states, " do not last long, disappearing 

 " generally in about six weeks or two months after they have 

 " been attained." Certain finches shed the margins of their 

 feathers in the spring, and then become brighter coloured, while 

 other finches undergo no such change. Thus the FHngilla tristis 

 of the United States (as well as many other American species) 



82 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. pp. 617, 637, 709, 711. Also 

 Blyth in ' Land and Water,' 1867, 

 p. 84. On the moulting of Para- 

 iisea, see an interesting article by 

 Dr. W. Marshall, ' Archives Neerlan- 

 iaises,' torn. vi. 1871. On the Vidua, 

 'Ibis,' vol. iii. 1861, p. 133. On 

 *.he Drongo-shrikes, Jerdon, ibid. 

 col. i. p. 435. On the vernal moult 



18 



of the Herodias bubdcus, Mr. S. S. 

 Allen, in 'Ibis,' 1863, p. 33. On 

 Gallus bankiva, 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. 



83 See Macgillivray, ' Hist. British 

 Birds ' (vol. v. pp. 34, 70, and 223), 

 on the moulting of the Anatidae, 

 with quotations from Waterton and 

 Mcntag'i. Also Yarrell, 'Hist, o/ 

 British Birds,' vol. iii. p. 243. 



