78 
ANAS RUBRIPES 
lieve the species can smell man. However, nearly all old shooters are quite convinced 
that Black Ducks have this power, and Giraud (1844) tells how the gunners of Long 
Island burned tow in order to disguise their presence ! 
Flight. Everything which has been said of the IMallard holds for this species. 
Very large migratory flocks are unusual. As we see them on or near the Atlantic 
coast in early autumn the typical flock is of five or six to a dozen or fifteen, and less 
often thirty or forty. Migratory flocks of sixty or seventy I should call unusual. 
At least, such large flocks do not often stop in our eastern ponds although large 
bodies of birds may gather, the result of many small, probably family parties, tem- 
porarily combined. Audubon thought that it was unusual to see them in flocks as 
large as is customary with the Mallard. 
Mated pairs flying about alone almost always show the female in front. \Mien a 
pair is jumped, the female forges ahead as soon as the birds get well under way. 
Black Ducks are easily recognized on the wing because they are so much darker 
than either the male or female Mallard. They have the same manner of flight as 
Mallards, that is, with a rather short wing-arc, the wings not depressed much below 
the level of the body. When they are mixed in with Florida Ducks they are also 
conspicuous by their darker color, especially about the head and neck. 
Association with other Species. Black Ducks are usually seen by themselves 
while migrating in New England, but sometimes there will be a single Green-winged 
Teal, a Mallard or two, or a Pintail among them. In winter on our Atlantic coast, 
east of New York, this species has almost no other river ducks to mix with. Farther 
south and west they associate very freely with IMallards, and also with Pintails, 
and Teals, less often with Gadwalls, Widgeons and Shovellers. Early in the winter 
Mallards begin to draw away from the Atlantic coast, so that the association on 
common ground does not last long. The association of Black Ducks with Herrings 
and Black-backed Gulls was mentioned under Wariness. 
Voice. Not to be distinguished from the Mallard’s. The windpipe, described 
by Audubon and others, has a tracheal pouch similar to that of the Mallard. 
Food. The food of this species in winter has been carefully studied by McAtee 
(1918). The result of the analysis of 390 stomachs from nineteen States and two 
Canadian Provinces is: animal matter, 24.09%, vegetable, 75.91%. Of the animal 
matter a little over half was made up of mollusks, mostly univalve shells. The com- 
mon blue mussel is very important, and shells of the genus Litorina were frequently 
taken, five species being identified. Twelve hundred shells were removed from the 
stomach of one bird. Crustaceans are next in importance, and under this head come 
