8IRD8. 445 



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 disk-formed tail-feathers of 

 certain drongos (Bhringa) in India, and with the elon- 

 gated 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 directly after 

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

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

 but not afterward; so that these latter species are interme- 

 diate 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 Janu- 

 ary, 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 ban- 

 kiva 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 domesti- 

 cated 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.* 



* For tlie 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 

 Paradisea, see an interesting article by Dr. W. Marshall, " Archives 

 Neerlandaises," torn, vi, 1871. On the Vidua, ' l Ibis," vol. iii, 1861, 

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

 vernal moult of the Herodias bubulcus, 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 " Vari- 

 ation of Animals nnder Domestication," vol. i, p. 236. 



