303. Anas boscas.
THE MALLARD or COMMON WILD DUCK.
Nilsir, India; Lilgah, Nepal; Niroji, Sind; Sabz-zurdan, Cabul; Sun,Yarkand.
Male 22 1/2" to 24"; 2 1/2 to 4 lbs. Female 20" to 21 1/2"; 2 to 2 1/2 lbs. Legs orange. Bill yellowish, nail black. Head emerald-green. White neck-ring. Chestnut gorget. Speculum Prussian blue, bordered black above and white below. Back vermiculated white and brown. Four central tail-feathers glossed purple and curled. Tail of twenty feathers. To avoid calling a drake a duck, the name of Wild Duck was dropped in favour of Mallard, which simply means Drake. After the breeding season the drake moults in June into female plumage. When the body-moult is complete, the bird loses its quills, and is for a time unable to fly. The ordinary male plumage is reassumed by a second moult in September. 20th August.
Our two Wild Ducks are very happy on the tank in the garden, and they have now been joined by a pair of Dabchicks. The mallard has lost his green head and his tail-curls, and is coloured as the female, only with his breast and back more rufous, his bill being now a bright dead yellow" (Kandahar in 1879, p. 249). —Female ; Brown, edged lighter. Head and neck yellowish, unspotted. Below buff, with brown centres. Tail brown, edged buff. The original source from which tame ducks are derived. Temperate regions of Northern Hemisphere, migrating south in winter. Breeds in the Himalayas and Kashmir. Unknown in S. India, Ceylon, Pegu, and Tenasserim. Six to twelve eggs (2.23 x 1.6), greenish white.
The Wild Ducks (A. boscas) afford an example of the changes of plumage in the different sexes, ages, and seasons of the year which may take place in certain species of birds.
At first the young are clothed with down, alike in colour. The down is soon replaced by true feathers. In this stage also the two sexes are almost exactly alike, both closely resembling the adult female.
The females, from the time they acquire their complete covering of feathers, remain for the rest of their lives practically alike, undergoing no change with the different seasons. Their dress is highly protective, being very inconspicuous as long as the birds remain among the reeds and sedges which grow in the places they usually frequent and where they make their nests.
The males for a considerable part of the year put on a very handsome and conspicuous dress, which attains its perfection shortly before the pairing season begins, or about mid-winter. By the time the young are hatched a change begins to take place, the brilliant plumage disappears, and the bird "goes into an eclipse," as Waterton described it. It loses all the characteristic appearance of the male, even the four curling central tail-feathers, and assumes a dress so closely resembling that of the female that at a little distance it is impossible to distinguish the sexes. While in this condition the moult of the large wing-feathers takes place, the bird being for a time unable to fly. After remaining in this garb about three months it rapidly acquires the winter dress, which is nearly complete by the beginning of October, although the brilliant glossy green of the head and the rich dark maroon of the breast are not yet fully developed, the feathers of the latter being bordered by a light edge which they afterwards lose.
Precisely similar changes take place in many other species of Duck, though not in all. In the Sheldrake (T. cornuta), for example, the males and females-are both conspicuously coloured, and change but little with the seasons. (N. H. M. J. 958. B. 1592.) See illustration, p. 267.
Also A. wyvilliana. 18". Like A. boscas, but speculum is greenish blue, and under tail-coverts black, mixed with chestnut. Sandwich Islands.
A. laysanensis. 17". Legs orange. Bill blackish. General plumage rufescent. Irregular-white ring round the eye. Speculum purple, green, and white. Laysan Islands.
Central tail-feathers not curled up.
A. melleri. 21". Legs flesh colour. Bill black. Feathers brown, margined red. Speculum, black, glossy green, and black. Madagascar.
A. obscura. 21". Legs orange. Bill yellowish. Feathers brownish black, edged pale-fulvous. Speculum glossy violet, surrounded by black. E. N. America and Bermudas.
A. fulvigula. Similar to A. obscura, but much paler. Speculum bluish green. Florida.
A. maculosa. Similar to A. fulvigula, but cheeks are streaked with brown. Speculum* purple. Texas and Kansas.
A. diem. Resembles A. fulvigula, but last row of wing-coverts with subterminal band of white, and secondaries with broad terminal bar of white. Speculum green. Mexico.
A. aberti. In colour like A. fulvigula. Secondaries widely tipped white, preceded by a black bar. Speculum grass-green. Mexico.
A. luzonica. 20". General plumage grey. Crown and nape brown. Eye-stripe, throat, and neck rufous. A black band from lores through eyes. Speculum black, green and black. Philippines.
A. superciliosa. 24". Legs yellow. Bill plumbeous, nail black. Above and below brown, edged buff. Band from forehead through eyes brown-black. Speculum black, green and black. Java to S. New Guinea, Australia, New Zealand, and Polynesia.
A. oustaleti. Similar to A. superciliosa, but paler below, and speculum bluish purple. Ladrone Islands.