Duck-the canvasback (aythya valisineria), historically known in the united states as a sheldrake, is a large diving duck, 4860 cm long and weighing 1270 g.the adult male has a black bill, a red head and neck, a black breast, red eyes and a whitish body. the adult female has a brown head and body and a black bill.their breeding habitat is north american prairie wetlands. the bulky nest is built from vegetation in a marsh and lined with down. loss of nesting habitat has caused populations to decline. canvasbacks usually take new mates each year, pairing in late winter.canvasbacks are strongly migratory and overwinter on the coasts of the united states, the great lakes and british columbia in saltwater bays, estuaries or lakes. this species is a very rare vagrant to western europe.
