DUCKS, GEESE, AND SWANS 
57 
The redhead is so similar to the canvas-back as to be easily mis¬ 
taken for it at a little distance, and in habits the resemblance is 
equally close. Goss says that this deep water duck, though widely 
distributed, is not so common on the Pacific slope as east of the 
Rocky Mountains. It is usually found in flocks on the open water 
associated with canvas-backs, and diving with them for its food, 
which consists of various kinds of submarine and fresh water plants, 
small mollusks, crustaceans, fish, frogs, and water newts. 
147. Aythya vallisneria (Wi7s.). Canvas-back. 
Bill three times as long as wide. Adult male: head and neck rich 
chestnut brown, becoming 
dusky on crown and face ; 
shoulders and chest black; 
sides and back light gray; 
belly white or grayish ; tail 
and quills dark gray ; feath¬ 
ers around base of tail black. 
Adult female: plumage 
mainly umber brown, becom¬ 
ing whitish around face and 
chin. Length: 20.00-23.50, 
wing 8.75-9.25, bill 2.10-2.50. 
Distribution. — Whole of 
North America, breeding in 
Colorado,Nevada, Minnesota, 
and northward to Fort An¬ 
derson and Fort Yukon. 
Nest. — Usually in reeds, 
grass, or rushes, in shallow 
water, a bulky mass of grass 
stems lined with down. Eggs: 
7 to 8, pale olive green. 
Fi s- 73 ‘ In its breeding range the 
canvas-back is largely a bird of the northern interior, while in winter 
it is found mainly in the bays and estuaries of the southern coasts, 
where it is attracted by its favorite food, the stems and bulbs of wild 
celery or eel grass, Vallisneria. While feeding on this plant the 
canvas-backs become fat and so delicately flavored as to outrank all 
other ducks in quality and market price. Hunted wherever they 
go, they have learned that existence depends on eternal vigilance, 
and so keep out in open water as far from shore as their feeding 
grounds will allow. Vernon Bailey. 
Subgenus Fuligula. 
148. Aythya marila (Linn.). Scaup Duck: Blue-bill. 
Bill short and wide, bluish with black tip. Male in breeding plumage : 
head black, glossed with green; shoulders, rump, and chest black ; belly 
white, margined along sides with light grayish; crissum black. Post- 
