CANVASS-BACK DUCK. 3 
forced a second time to migrate, and betake itself to warmer parts of 
the country, where it continues during the rest of the winter. 
The flight of this species, although resembling that of our larger 
sea-ducks in having the appearance of being rather laboured, is strong, 
rapid, at times very elevated, and well sustained. It swims deeply, es- 
pecially when under apprehension of danger, and this probably the 
better to enable it to escape by diving, at which it is almost as ex- 
pert as our sea or diving ducks. But although its speed on the water 
is considerable, it moves rather heavily on land. Its food varies, ac- 
cording to the season and locality. The plant named Valisnerta, on 
which it is said to feed when on the head waters of the Chesapeake, 
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 which have been in greater or less quantity 
found in their stomach. 
Nothing is known of its manners during the breeding season; and 
we are equally ignorant of the changes of plumage which, like other 
species, it may undergo at that period. 
As I have not had very good opportunities of making myself ac- 
quainted with the modes in which the Canvass-backs are obtained for 
the markets, I here present an account of duck-shooting on the waters 
of the Chesapeake, published some years ago in the “ Cabinet of Natu- 
ral History,” and of which a copy has been transmitted to me by its 
author, Dr J. J. Suarpxess, of Philadelphia, to whom, for this and 
other marks of attention, I offer my best thanks. 
“The Chesapeake Bay, with its tributary streams, has, from its 
discovery, been known as the greatest resort of water-fowl in the 
United States. This has depended on the profusion of their food, 
which is accessible on the immense flats or shoals that are found near 
the mouth of the Susquehanna, along the entire length of North-East 
and Elk Rivers, and on the shores of the bay and connecting streams, 
as far south as York and James Rivers. 
“The quantity of fowl of late years has been decidedly less than 
in times gone by; and I have met with persons who have assured me 
that the number has decreased one-half in the last fifteen years. This 
change has arisen, most probably, from the vast increase in their de- 
B2 
