376 



THE CANVASS-BACKED DUCK. 



parallel to their most northern limits, and at this period associates 

 much on the water with the ordinary tribe of Ducks. After the close 



of the period of 

 reproduction, accu- 

 mulating in flocks, 

 and driven to the 

 open waters of the 

 south for their 

 favorite means of 

 subsistence, they 

 nrrive about the 

 middle of October 

 seawards on the 

 coast of the United 

 States. A few at 

 this time visit the 

 Hudson and the 

 Delaware,- but the 

 great body of emi- 

 grants take up their 

 quarters in the Bay of Chesapeake, and in the numerous estuaries and 

 principal rivers which empty into it; particularly the Susquehanna, 

 the Patapsco, Potomac and James' rivers. They also frequent the 

 sounds and bays of North Carolina, and are abundant in the river 

 Neuse, in the vicinity of Newbern, and probably in most of the other 

 southern waters to the coast of the Gulf of Mexico, being seen in 

 winter in the mild climate of New Orleans. In these different 

 i'ictions of the Union they are known by the various names of 

 (Janvass-Backs, White Backs, and Sheldrakes. In the depth of 

 'vinter, a few pairs, probably driven from the interior by cold, arrive 

 in Massachusetts Bay, in the vicinity of Cohasset and near Martha's 

 Vineyard : these, as in the waters of New York, are commonly 

 associated with the Eed-Head, or Pochard, to which they have so 

 near an affinity. Their principal food, instead of the fresh-water 

 ,)lant Valisneria, which is confined to so small a space, is, in fact, 

 the different kinds of Sea- Wrack, known here by the name of 

 Kelgrass, from its prodigious length, (Zostera marina, and Ruppia 

 maritima.) These vegetables are found in nearly every part of the 

 Atlantic, growing like submerged fields over all the muddy flats, 

 shallow bays, estuaries, and inlets, subject to the access of salt or 

 brackish waters. They are the marine pastures in which most of the 

 Sea Ducks, no less than the present, find at all times, except in 

 ievere frosts, an ample supply of food. 



The Canvass-Backs on their first arrival are generally lean, but 'ly 

 the beginning of November, the}'' become in good order for the table. 

 They are excellent divers, and swim with speed and agility. They 

 sometimes assemble by thousands in a flock, and rising suddenly 

 on wing produce a noise like thunder. During the day, they are 

 commonly dispersed about in quest of food, but towards evening col- 

 lect together, and coming into the creeks and river inlets, ride as it 



