Breeding
Canvasbacks breed in the Prairie Pothole Region of North America. They prefer to nest over water on permanent Prairie marshes surrounded by emergent vegetation, such as cattails and bulrushes, which provide protective cover. Other important breeding areas are the sub-arctic river deltas in Saskatchewan and the interior of Alaska. Female canvasbacks lay an average of 7-8 eggs and female redheads often parasitize their nests.
Latin: Aythya valisineria
Average length: M 21", F 20"
Average weight: M 2.7 lbs., F 2.5 lbs.
Description
Male canvasbacks have a chestnut-red head and neck, a black breast, grayish back, black rump and blackish-brown tail. The sides, flank and belly are white, while the wing coverts are grayish and vermiculated with black. 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. Female canvasbacks have 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.
Food Habits
Canvasbacks are omnivorous, although they consume a diet primarily composed of aquatic vegetation. Often diving while foraging, they feed on the tubers, rhizomes, and seeds of plants such pondweeds, wild celery, and bulrushes. Canvasbacks also eat significant amounts of animal matter such as insects and mollusks.
Population
The canvasback population is continuing to rebound from the low levels experienced in the late 1980s and early 1990s caused by loss of breeding and wintering habitat and lead poisoning due to ingestion of spent shot while feeding (this threat should gradually disappear with the lead shot ban).
Migration and Wintering
Canvasbacks migrate through the Mississippi Flyway to wintering grounds in the mid-Atlantic United States and the Lower Mississippi Alluvial Valley (LMAV), or the Pacific Flyway to wintering grounds along the coast of California. Historically, the Chesapeake Bay wintered the majority of canvasbacks, but with the recent loss of submerged aquatic vegetation in the bay, their range has shifted south towards the LMAV. Brackish estuarine bays and marshes with abundant submerged aquatic vegetation and invertebrates are ideal wintering habitat for canvasbacks.
