Sago pondweed (Potamogeton pectinatus)tubers are what give
Canvasbacks their unique nutty flavor. That is why they sold for ten times the price of Mallards in the market hunting days. The plant is also a staple of Tundra Swans, and when they are feeding American Wigeon are usually there to eat the scraps. The tubers are like thin potatoes about 3/4" long and the birds dig them from the bottom soils. Canvasback hunting is almost a thing of the past around here, as the high water levels have destroyed the sago beds. Ditto with wigeongrass (Ruppia), another favorite food of migrant waterfowl.