604 CANVASS-BACK DUCK. 
of the two, I have designated this as a new species, and shall proceed 
to detail some particulars of its history. 
The Canvass-Back Duck arrives in the United States from the north 
about the middle of October ; a few descend to the Hudson and Dela- 
ware, but the great body of these birds resort to the numerous rivers 
belonging to and in the neighborhood of the Chesapeake Bay, particu- 
larly the Susquehannah, the Patapsco, Potomac, and James Rivers, 
which appear to be their general winter rendezvous. Beyond this, to 
the south, I can find no certain accounts of them. At the Susquehan- 
nah, they are called Canvass-Backs; on the Potomac, White-Backs ;. 
and on James River, Sheldrakes. They are seldom found at a great 
distance up any of these rivers, or even in the salt-water bay; but in 
that particular part of tide water where a certain grass-like plant 
grows, on the roots of which they feed. This plant, which is said to 
be a species of valisineria, grows on fresh-water shoals of from seven 
to nine feet, (but never where these are occasionally dry,) in long, nar- 
row, grass-like blades, of four or five feet in length ; the root is white, 
and has some resemblance to small celery. This grass is in many 
places so thick that a boat can with difficulty be rowed through it, it 
so impedes the oars. The shores are lined with large quantities of it, 
torn up by the Ducks, and drifted up by the winds, lying, like hay, in 
windrows. Wherever this plant grows in abundance, the Canvass- 
Backs may be expected, either to pay occasional visits, or to make it 
their regular residence during the winter. It occurs in some parts 
of the Hudson; in the Delaware, near Gloucester, a few miles below 
Philadelphia ; and in most of the rivers that fall into the Chesapeake, 
to each of which particular places these Ducks resort; while, in 
os unprovided with this nutritive plant, they are altogether un- 
nown, 
On the first arrival of these birds in the Susquehannah, near Havre- 
de-Grace, they are generally lean; but such is the abundance of their 
favorite food that, towards the beginning of November, they are in 
pretty good order. They are excellent divers, and swim with great 
speed and agility. They sometimes assemble in such multitudes as 
to cover several acres of the river, and, when they rise suddenly, pro- 
duce a noise resembling thunder. They float about these shoals, div- 
ing, and tearing up the grass by the roots, which is the only part they 
eat. They are extremely shy, and can rarely be approached, unless 
by stratagem. When wounded in the wing, they dive to such pro- 
digious distances, and with such rapidity, continuing it so persevering- 
ly, and with such cunning and active vigor, as almost always to render 
the pursuit hopeless. From the great demand for these Ducks, and 
the high price they uniformly bring in market, various modes are prac- 
tised to get within gunshot of them. The most successful way is 
‘said to be decoying them to the shore by means of a dog, while the 
gunner lies closely concealed in a proper situation. The dog, if 
properly trained, plays backwards and forwards along the margin of 
the water; and the Ducks, observing his manceuvres, enticed perhaps 
by curiosity, gradually approach the shore, until they are sometimes 
within twenty or thirty yards of the spot where the gunner lies con- 
cealed, and from which he rakes them, first on the water, and then as 
they rise. Thys method is called tolling them in. If the Ducks scem 
