BLACK DUCK 163 



olive of maturity. Feet of young male change from orange brown to salmon or orange 

 red by January. Feet of young female change from brownish to brownish with some 

 orange or salmon colour by mid-winter. The juvenile tying is not moulted until the 

 first postnuptial moult during the following summer. Except for the wing, plumage 

 is practically adult by December. Wing of Both Sexes. Like that of corresponding 

 adult, but greater coverts have narrower, and less distinct, dusky tips; tertials, smaller 

 more rounded at tips, browner and duller; three outer secondaries show less irides- 

 cence, and all secondaries narrower. 



The conclusion that may be drawn from the foreging descriptions is that the] 

 differences which exist between the two forms of Black Ducks are due entirely to age, 

 sex, and moult, and that: 



(1) The bird generally known as the Red-legged Black Duck, taken by gunners 

 in the late autumn, is a full-plumaged adult male or an old female. 



(2) The bird generally known as the Common Black Duck, taken by gunners 

 in early to razd-autumn, is either (a) an adult male emerging from the summer 

 moult, (b) an adult female, or (c) a juvenile. 



(The colour change in the bill and feet of the Black Duck, as it progresses 

 toward maturity, is paralleled in the Mallard. In the Mallard, however, it has been 

 long recognized that these variations are due to age, sex, and moult.) 



SPECIMEN IDENTIFICATION 



BOTH SEXES. General effect: A large duck, with the entire plumage dark 

 mottled brown. Chief distinguishing features (a) hind toe without lobe, (b) bright 

 purplish-blue speculum, bordered in front and behind with black bars, (c) bill, see 

 "Description," (d) feet, see "Description," (e) crown, dark; head and neck, creamy 

 white, uniformly streaked with dusky. 



The Black Duck may be distinguished from the other mottled-brown ducks of 

 this subfamily as follows: The Florida and Mottled Ducks have yellow-orange bill 

 with black spot at base; throat and chin are light buff with few streaks; feathers of 

 back have broader, more cinnamon-buffy edges. The New Mexican Duck and the 

 female Mallard have prominent white bars in front of and behind the speculum. 

 The female Pintail has a pale speculum, with cinnamon or buffy-white border in 

 front, blue-grey feet and more pointed tail. 



JUVENILES. See "Description." 



FIELD MARKS 



ON THE WATER. The sexes are alike; the appearance is that of a very large, 

 sooty-black duck, with head and neck noticeably paler; general coloration darker 

 than that of female Mallard. They swim lightly 

 gracefully, and at considerable speed. The absence 

 of the two white bars of the speculum, and the 

 absence of white in the tail will separate in- 

 dividuals from female Mallards. On the Atlantic 

 coast in winter they may, in the distance, be 

 confused with Scoters, which are also large black 

 ducks but have stouter heads and shorter necks. 

 The restricted range of the New Mexican, Florida, and Mottled Ducks, which are 

 very similar to the Black, will minimize confusion with this species. 



