up of Baltic Clams, which are very common in the Chesapeake Bay: the ducks have been able to adapt to the decline in SAV by changing their diet. Redheads, which also feed on SAV tubers, have not been able to adapt, and their population remains low. Canvasbacks are omnivores, eating everything from seeds to plant tubers and from mussels to insects. During the breeding season they eat both plant and animal foods, but during migration and winter they primarily eat rhizomes and tubers from aquatic plants. Canvasbacks dive straight down to depths of around 7 feet to extract pieces of aquatic plants with their bill. Other food is taken from or just below the surface of the water. Cuisine Canvasback ducks were a particularly prestigious game dish in mid-19th-century America. They were rarely found on everyday menus, and often featured at banquets. They were generally sourced from Maryland and Chesapeake Bay, and their flavor was attributed to their diet of wild celery. By the end of the century, though, they had become "scarce, expensive, or unobtainable". Edith Wharton refers to canvasback with blackcurrant sauce as an especially luxurious dinner served in New York City in the 1870s. Canvasback duck was a canonical element, along with Terrapin à la Maryland, of the elegant "Maryland Feast" menu, an "elite standard... that lasted for decades". Conservation Populations have fluctuated widely. Low levels in the 1980s put the canvasback on lists of special concern, but numbers increased greatly in the 1990s. The canvasback is particularly vulnerable to drought and wetland drainage on the prairies of North America. Many species of ducks, including the canvasback, are highly migratory, but are effectively conserved by protecting the places where they nest, even though they may be hunted away from their breeding grounds. Protecting key feeding and breeding grounds is key for conserving many types of migratory birds. References External links Canvasback - Aythya valisineria - USGS Patuxent Bird Identification InfoCenter Aythya Native birds of Alaska Native birds of Western Canada Native birds of the Canadian Prairies Native birds of the Northwestern United States Birds described in 1814 Taxa named by Alexander Wilson (ornithologist) Extant Pleistocene first appearances