Species XVIII. ANAS VALISNERIA. 



CANVAS-BACK DUCK. 



[Plate LXX. Fig. 6.] 



This celebrated American species, as far as can be judged from tbe 

 best figures and descriptions of foreign birds, is altogether unknown in 

 Europe. It approaches nearest to the Pochard of England, Anas ferina, 

 but differs from that bird in being superior in size and weight, in the 

 greater magnitude of its bill, and the general whiteness of its plumage. 

 A short comparison of the two will elucidate this point. The Canvas- 

 back measures two feet in length, by three feet in extent, and when in 

 the best order weighs three pounds and upwards. The Pochard, accord- 

 ing to Latham and Bewick, measures nineteen inches in length, and 

 thirty in extent, and weighs one pound twelve or thirteen ounces. The 

 latter writer says of the Pochard, " the plumage above and below is 

 wholly covered with prettily freckled slender dusky threads disposed 

 transversely in close set zigzag lines, on a pale ground, more or less 

 shaded off with ash ;" a description much more applicable to the bird 

 figured beside it, the Red Head, and which very probably is the species 

 meant. In the figure of the Pochard given by Mr. Bewick, who is 

 generally correct, the bill agrees very well with that of our Red Head ; 

 but is scarcely half the size and thickness of that of the Canvas-back ; 

 and the figure in the Planches Enluminees corresponds in that respect 

 with Bewick's. In short, either these writers are egregiously erroneous 

 in their figures and descriptions, or the present Duck was altogether 

 unknown to them. Considering the latter supposition the more proba- 

 ble of the two, I have designated this as a new species, and shall pro- 

 ceed to detail some particulars of its history. 



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

 about the middle of October, a few descend to the Hudson and Dela- 

 ware, but the great body of these birds resort to the numerous rivers 

 belonging to and in the neighborhood of the Chesapeake Bay, particu- 

 larly the Susquehanna, the Patapsco, Potomac, 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 Susquehanna 

 they are called Canvas-backs, on the Potomac 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 



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