BIRDS OF PENNSYLVANIA 
43 
similar to preceding species. Female has dark reddish-brown eyes ; bill black, and 
with the exception of bill is very similar to female Red-head. Length about 23 
inches ; extent about 33 inches. 
Habitat . — Nearly all of North America, breeding from the northwestern states 
northward to Alaska. 
This well-known and hig-hly-esteemed g-ame bird is found as a 
tolerably frequent spring- and fall mig-rant, and occasionally as a winter 
visitor on the Susquehanna river, southward from Harrisburg-. In other 
sections of our state it appears to occur only as a rare or casual visitor. 
Audubon, writing- of the food of the Canvas-back, says : ‘‘ It varies ac- 
cording- to the season and locality. The plant Vallisneria, on which it 
is said to feed when on the headwaters of the Chespeake, is not found 
equally abundant in other parts, and even there is at times so reduced 
in quantity that this duck, and several other species which are equally 
fond of it, are obliged to have recourse to fishes, tadpoles, water-lizards, 
leeches, snails and mollusca, as well as such seeds as they can meet with, 
all of which have been in greater or less quantity found in their 
stomachs.” 
My examinations of four of these ducks, which were killed at Havre- 
de-Grace, showed only vegetable substances, which I judged to be re- 
mains of Vallisneria. 
Wilson asserts that the Canvas-backs when feeding on the Vallisneria 
eat only the roots, and, on the other hand, the Red-heads feed on the 
stems of this plant. 
Aythya marila nearctica Stejn. 
American Scaup Duck ; Big-Black-liead ; Blue-bill. 
Description. 
Bill blue, rather broad and heavy, and about as long as head; tarsi dark lead 
color ; iris yellow ; head, neck fore part of breast black ; sides of head glossed with 
green ; lower part of back, including rump, tail and coverts black and dark- 
brownish (but black predominates) ; speculum, greater portion of under plumage, 
white ; inter-scapulars, scapulars and sides grayish or white, with five irregular 
black and transverse lines ; wing coverts brownish. 
Female . — Conspicuous patch of white about base of maxilla ; head, neck, sides 
an upper parts generally brown and blackish ; lower part of breast and belly, except 
lower part which is brownish-gray, white. Length about 20 inches ; extent about 33. 
Habitat . — North America, breeding far north. 
The Big Black-head or Blue-bill, as this species is usually knowm to 
sportsmen, is a moderately abundant spring and fall migrant, and gen- 
erally a few remain with us in winter. This and the Little Black-head, 
and occasionally other species, are often found together in flocks. This 
duck feeds principally on different kinds of aquatic animal life (other 
than fish) and it also, sometimes, eats seeds and the tender parts of 
several kinds of plants which grow in our rivers. 
