CANVAS-BACK DUCK. 337 



the Gulf of Mexico, being seen in winter in the mild climate 

 of New Orleans. In these different sections of the Union they 

 are known by the various names of Canvas-backs, White- 

 backs, and Sheldrakes. In the depth of winter a few pairs, 

 probably driven from the interior by cold, arrive in Massachu- 

 setts Bay, in the vicinity of Cohasset and near Martha's Vine- 

 yard ; these, as in the waters of New York, are commonly 

 associated with the Red-head, or Pochard, to which they have 

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

 water plant Valisfieria, which is confined to so small a space, 

 is in fact the different kinds of sea-wrack, known here by the 

 name of eel-grass, from its prodigious length. These vege- 

 tables 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, ex- 

 cept in severe frosts, an ample supply of food. 



The Canvas-backs on their first arrival are generally lean ; 

 but by the beginning of November they 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 collect together, and coming into 

 the creeks and river inlets, ride as it were at anchor, with their 

 heads under their wings asleep ; sentinels, however, appear 

 awake and ready to raise an alarm on the least appearance of 

 danger. At other times they are seen swimming about the 

 shoals and diving after the sea-wrack, which they commonly 

 pluck up, and select only the tenderest portion towards the 

 root. Though thus laboriously engaged, they are still ex- 

 tremely shy, and can rarely be approached but by stratagem ; 

 for even while feeding, several remain unemployed, and vigilant 

 against any surprise. When wounded in the wing, they dive to 

 prodigious distances, and with such rapidity and perseverance 

 as almost to render the pursuit hopeless. The great demand 



VOL. II. — 22 



