Canvasback n. : A Species of duck (Aythya vallisneria), esteemed for the delicacy of its flesh. It visits the United States in autumn; particularly Chesapeake Bay and adjoining waters; -- so named from the markings of the plumage on its back.

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Taxonomy
Canvasback, Aythya valisineria, free encyclopedia, species, adult, black bill, body, nest, least concern, United States, search, Kingdom, Phylum, Family, Genus, vallisneria, historically, Sheldrake.

Defination from the web:
Canvasback (Aythya valisineria), historically known in the United States as a "Sheldrake", is a large diving duck, 48 ... Black Duck · Canada Goose · Canvasback · Gadwall · Greater Scaup · Lesser Scaup · Mallard · Northern Pintail · Redhead · Ross's Goose · Snow Goose · Wood Duck ...