From Mike Checkett's - "Biologist Blog"
The aristocrat of diving ducks, the distinctive and handsome canvasback (Aythya valisineria) is also the least numerous of all North American diving ducks.
About the same size as mallards, canvasback are chunkier and swifter in flight, and in fact are one of the swiftest of all waterfowl, having been clocked reliably at 74 miles per hour. Their wingbeat is rapid and noisy, and their flight is direct, with little weaving or up-and-down movement of flocks. In migration, they often fly in precise V formations.
This beautiful bird's most distinctive feature is its head, which is decidedly wedge shaped, with only a shallow dipping arc from the tip of its bill to the top of its head. Only some eiders share a similar profile. The bill of both males and females is black, though the hen's is sometimes dark gray. Its feet are gray blue. The drake's eyes are a piercing, bright red; the hen's are black.
In breeding (nuptial) plumage, the male's chestnut red head is rimmed beneath with a broad black band that extends around the neck and chest. His rump is also black, but his back, breast, sides and flanks are white, and even in flight, no duck shows more white than the canvasback drake. The name canvasback comes from the delicate dark vermiculations on the feathers of the back, yielding a fine wave-like pattern reminiscent of the weave of canvas.
Hens have unmottled, fawn brown heads and chests, and darkly mottled brown backs and flanks. The neck frequently is so light in color, it almost appears white. The female also has a blackish rump, though not as distinct as the male.
Most canvasbacks breed in the Prairie Pothole and parkland regions, but significant numbers fly on to the marshes in the subarctic, especially the Saskatchewan and Athabasca river deltas, Old Crow Flats and interior Alaska.
The 2006 May Breeding population estimate of canvasback's (0.7 ± 0.1 million) was 33 percent higher than last year's and was 23 percent higher than the long-term average.
Canvasback breeding population graph courtesy of the USFWS.
Trends of other waterfowl species.