DOUBLE ANNUAL, MOULT. 387 



also reason to believe that with certain bustards and rail-like 

 birds, which properly undergo a double moult, some of the older 

 males retain their nuptial plumage throughout the year. A few 

 highly modified feathers may merely be added during the spring 

 to the plumage, as occurs with the disc-formed tail-feathers of 

 certain drongos (Bhringa) in India, and with the elongated 

 feathers on the back, neck, and crest of certain herons. By such 

 steps as these, the vernal moult might be rendered more and 

 more complete, until a perfect double moult was acquired. Some 

 of the birds of paradise retain their nuptial feathers throughout 

 the year, and thus have only a single moult; others cast them di- 

 rectly after the breeding-season, and thus have a double moult; 

 and others again cast them at this season during the first year, 

 but not afterwards; so that these latter species are intermediate 

 in their manner of moulting. There is also a great difference 

 with many birds in the length of time during which the two 

 annual plumages are retained; so that the one might come to be 

 retained for the whole year, and the other completely lost. Thus 

 in the spring Machetes pugnax retains his ruff for barely two 

 months. In Natal the male widow-bird (Chera progne) acquires 

 his fine plumage and long tail-feathers in December or January, 

 and loses them in March; so that they are retained only for 

 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 bankiva retains his neck-hackles 

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

 lying 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, as to part of the plumage, a double moult changed under 

 domestication into a single moult.'* 



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 extraordinary 



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

 old males retaining their nuptial plumage, se& Jerdon, on bustards 

 and plovers, in 'Birds of India,' vol. iii. pp. 617, 637, 709, 711. Also BlyLh 

 in 'Land and Water,' 1S67, p. 84. On the moulting of Paradisea, see an 

 Interesting article by Dr. W. Marshall, 'Archives Neerlandaises,' torn. 

 vl. 1871. 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 bubul- 

 cus, 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. 



