# UKBirds

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## Canvasback

### Aythya valisineria

The Canvasback is the largest of the North American diving ducks, that ranges from between 48-56 centimetres (19-22 in) long and weighs approximately 862-1,588 grams (1.90-3.50 lb), with a wingspan of 79-89 centimetres (31-35 in). The canvasback has a distinctive wedge-shaped head and long graceful neck. The adult male (drake) has a black bill, a chestnut red head and neck, a black breast, a grayish back, black rump, and a blackish brown tail. The drake's sides, back, and belly are white with fine vermiculation resembling the weave of a canvas, which gave rise to the bird's common name. The bill is blackish and the legs and feet are bluish-gray. The iris is bright red in the spring, but duller in the winter. The adult female (hen) also has a black bill, a light brown head and neck, grading into a darker brown chest and foreback. The sides, flanks, and back are grayish brown. The bill is blackish and the legs and feet are bluish-gray. Its sloping profile distinguishes it from other ducks.
The species name valisineria comes from Vallisneria americana, the scientific name of wild celery, whose winter buds and rhizomes are the Canvasback's preferred food during the nonbreeding period. The duck's name is based on early European inhabitants of North America's assertion that its back was a canvaslike color. In other languages it is just a white-backed duck; for example in French, morillon - dos blanc, or Spanish, pato lomo blanco. In Mexico it is called pato coacoxtle.