CANVAS-BACK DUCK. 341 



The Canvas-back Duck arrives in the United States from the 

 north about the middle of October, a few descend to the Hud- 

 son and Delaware, but the great body of these birds resort to 

 the numerous rivers belonging to and in the neighbourhood of 

 the Chesapeake Bay, particularly the Susquehannah, the Pa- 

 tapsco, Potowmac, 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 Susquehannah they are 

 called Canvas-backs, on the Potowmac 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 narrow grass-like blades of four 

 or five feet in length; the root is white, and has some resem- 

 blance 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 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 oc- 

 curs in some parts of the Hudson; in the Delaware near Glou- 

 cester, 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 nutri- 

 tive 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 abun- 

 dance of their favourite 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, produce a noise resembling 



