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Show SEXUAL SELECTION: BIRDS. PAnT II. 84: 1 te until a perfect double dered more and more comple . '. n also be shown to ··eel A arac atwn ca moult was acqun - · ~ . d ··no<- ' which 01• t1 1 er . h 1 ath of time Ull o . ht exist m t e e~b . d. so that the one mig annual plumage IS£r· eta~e 'hole ye·u the other being come to be retained or t el w 1\Jr het;s 'pugnax retains complete1 Y 1o s t · T.h us t 1.e b :1.. a1c two months. Th 0 his ruff in the sprmg fo, arc :cquires in Natal hi::; male widow-bird ( Oher: ~:~i-::fh~rs in December or fine plumage and lono . u ·ch. so that they are· d loses them m .1.um ' · J n,nuary an. b t th ·ee months. Most spec1es rot~jnecl ~ur~ng ~nly :bl~u mot~lt keep their ornamental whJeh undeigo a d~ nths The male, however, of feathers for about SIX7 ~o t ··ns his n~ck-harkles for 'ld G llus bantcwa rc ai ff tl the WI a . and when tl1esc are cast o ' le nine or ten months' the neck are fully exposed underlying black featberds on . . ted descendant of this B t ith the omestlCa ' . to view. u w ~ f tl e male arc immediate1 Y species, the neck-hacl\.les otb t1 ve here see with respect replacec1 bY ew ones · so a ' ' d 11 ; double moult changed un er to part of the plumab~' a lt 77 . t' · to a smo1e mou · f domest!Ca Ion m . ~ (Anas boschas) is well known a ter The con:mon diake lose his male plumage for a the brecdmg-season to l . hi'ch time he assumes f b months Clunng w period o t re~ 'Th ale pintail-duck (Anas-that of the f~male. e /~ .. the shorter lleriocl of ) 1 Ius plumao-e lOI • 1 t acuta oses ho. . cl Montao·u remarks t 1a Rix weeks or two mont s ' an - ___:_.., -- . 'C"'etrd to partial mou1ts, und on ii }'or the foregoing ~tatcmc~is \n I ~:o sec Jordon, on busrords uncl olJ. males rctnining thou .n~ptta .? u~n~l7' 637, 709, 711. Als_~. B\ytll plover:;, in 'Birds of !ndl;t, vo1S;u· hn 'th~ Viduu, 'Ibis,' vol. 111. 1 61, in' Land nnd Wa1cr, 186~, ~·. . crdon ibid. vo1. i. P· 435 .. ~n the un On the Drungo s1mJ,c ' J J.I. S R A1lcn in ' lbJs, 1 63, ~~rn;l· moult of the Iler?dias uttb~tl~~s; A~;1nl~· ~nd :Mng. of ~at. ~list.: '13 On Gallus bcmlc~t'a, B\ytl'. u· t y 'Vnrintion o[ Annnuls p.1. '.' 1818 p. 455; sec, also, on t1us ~u JCC 'm vo . 1. ' ' l . 236 under Domcstico.tion, vo . J. p. . CIIAP. XJ!I. DOUBLE ANNUAL l\IOUL'l'. 85 " this double moult within so short a time is a most u extraordinary circumstance, that seems to bid defiance '' to all human reasoning." But he who believes in the gradual modification of species will be far from feeling surprise at finding gradations of all kinds. If the malo pintail were to acquire his new plumage within a still shorter period, the now male featherti would almost necessarily be mingled with the old, and both with some proper to the female; and this apparently .is tho case with the male of n. not distantly-allied bird, namely tlle JJfe1·ganser serrato1·, for the males arc 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.78 Some male birds, as before stated, become more l.n·ightly colomed iu tho spring, not by n. vernal monlt, but either by an actual change of colour in the feathers, or by tlwir obseurcly-colourcd deciduary margins being f:lhed. Changes of colour thus caused may last for a longer or shorter time. ' ·Vith the Pelecanus onocroialus a beautiful rosy tint, with lemon-coloured marks on tbe breast, overspreads tho whole plumage in the spriug; but these tints, as 1\Ir. Sclatcr states, ''do not last long, dis" appearing generally in about six weeks or two months "after they have been attained." Certain :finches Rhccl the margins of their feathers in the spring, and tl1en become brighter-coloured, whHe other finches undergo no such change. Thus the Fringilla tr1'stis of the United States (as well as many other American species), exhibits its bright colours only when the winter is ptlst, whilst onr goldfinch, which exactly represents this bird iS Sec Macgillivrny, 'IIi st. British Birds' (vol. v. p. 31, 70, and 223), on the muu1ting of the Anu.tidro, with quotations from Watcrton and 'Montngu. Also Yurrcll, • IIist. of British Birds,' vol. iii. p. 213. |