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CANVAS-BACK DUCK. 29 
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 wind-rows. Wherever this plant grows in abundance, 
the canvas-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 waters 
unprovided with this nutritive plant they are altogether 
unknown. 
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 favourite food, that, towards the beginning 
of November, they are in pretty good order. ‘They are excel- 
lent 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, produce a noise 
resembling thunder. They float about these shoals, diving 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 prodigious distances, and with such rapidity, continu- 
ing it so perseveringly, and with such cunning and active 
vigour, 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 practised 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 concealed, and from which he rakes 
