Canvasback Aythya valisineria and Canvas/Pochard hybrids

Canvasback male
Canvasback
The Canvasback is an North American duck related to the similar-looking Eurasian Common Pochard. It is bigger than the Pochard with a longer neck, - surprisingly long for a duck, a more angular head and all black bill. Both drakes have red eyes.
Canvasback female
Canvasback female
Canvasback females
Female Canvasbacks, above, have brown eyes and plainer plumage, also similar to a large, long-necked, female Common Pochard.
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Canvasback
Canvasback
Canvas-back
The ducks shown immediately above and all below, photographed in London, have mixed heritage; all but one of the drakes shown have a tiny patch of blue on their black bills, betraying hybridism with the Pochard.
Canvas-back
Canvas-back
Canvas-back
Canvas-back
Canvas-back
Canvas-back
Canvas-back
Canvas-back
Canvas-back
The female is similar to a large female Pochard with all-black bill. The small blue spot on the bills above indicates a Canvasback/Pochard hybrid.
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Canvas-back
Canvas-back
Canvas-back
More of the Common Pochard hybrid female (not Canvasback); other parent unknown. (Long black angular bill reminiscent of Canvasback.)