Canvasback

Aythya valisineria

(c) Ashok Khosla
  • ANATIDAE
  • Swans, Geese, Ducks
  • Anseriformes
  • Pato Coacoxtle
  • Fuligule à dos blanc
Introduction
The Canvasback is supremely adapted to the water and rarely ventures onto land. Diving as many as ten times in five minutes, this handsome duck has a long bill for probing deep into submerged mud. A wary disposition, general scarcity, and the male's dapper plumage make Canvasback sightings a great reward for bird watchers.
(c) Glen Tepke
Appearance Description

On average, these large diving ducks are 21 inches long, and weigh 2.7 pounds, with a wingspan of 29 inches. Canvasbacks have large feet, a thick neck, and a flat forehead that forms a wedge with the long bill. The drake Canvasback sports red eyes and a chestnut head and neck, accentuated by a black bill, crown, and nape. Neat demarcations separate the chestnut neck, black chest, and white body. The black tail and chest frame the drake’s white body. The female Canvasback also has a black bill, but she is soft brown from head to chest, as well as on her tail and coverts. Between the head and tail, her body is a pale grayish brown. The hen’s eyes are black.

Range Map
Courtesy Kenn Kaufman
Range Distribution
Canvasbacks breed exclusively in North America from the northern Great Plains into eastern Oregon, then north through the Canadian prairies into the interior of Alaska. Wintering Canvasbacks range along the mid-Atlantic states south through Georgia and then westward into Arizona. They winter as far north as Missouri and as far south as central Mexico. Along the west coast, this diving duck winters from Puget Sound through Baja California. During migration, the Canvasback can be found across most of the United States.
 
A legend for the range map to the right can be found here.
Habitat

Canvasbacks breed in deep water marshes, ponds, prairie potholes, and lakes with emergent plants like bulrushes, reeds, and cattails. During migration, this diving duck uses a variety of fresh and salt water lagoons, impoundments, river bends, backwaters, estuaries, deep lakes, and bays with plenty of submerged plants and mollusks for food. Wintering Canvasbacks use similar habitats, but tend to congregate coastally.

Feeding
A heavy body and large feet help keep the Canvasback perpendicular as it forages in the mud beneath still bodies of water. Diving from nine to 30 feet, this duck catches and consumes large amounts of clams, mussels, snails, and insects. Canvasbacks also dig in submerged mud with their feet, eat the succulent parts of aquatic plants like wild celery and sago pond weed, and pick items from the water’s surface or from the air. During the breeding season, females tend to eat more animal prey.
Reproduction
Canvasbacks begin forming monogamous pairs during migration. Several males attend one female and use various displays and vocalizations that include clucks, coos, murmurs, and coughs. Females select mates and choose nesting sites near their own hatching places. Tucked among young plants just above the water, the female builds a mound of dry plants arranged loosely and lined with fine vegetation and down. The female lays about eight greenish eggs. When other ducks (like Canvasbacks and Redheads) lay eggs in her nest, the overall clutch size remains the same but the host’s clutch size may be reduced by as much as 30%. This “brood parasitism” often causes a nest to be abandoned. When water levels drop, predation by foxes and raccoons also becomes high, and an entire breeding season’s worth of young can be lost within a vast breeding range.
Incubation lasts nearly four weeks, and the males guard their chicks against predators and other ducks for about two weeks, before forming flocks and beginning their migration. Canvasback chicks emerge ready to preen, swim, and forage. Females lead chicks to food and safety, but do not feed them. Hens depart after three to seven weeks, depending on the weather and the lateness of the season. Young Canvasbacks fledge in about 62 days.
Migration
In flocks of ten to 50, Canvasbacks migrate in V-formation and use all four North American flyways along traditional short to medium-length routes. Fall migrants sort themselves by age and sex, departing as early as mid-August and arriving as late as the end of November. Spring migrants fly in mixed-sex flocks in order to pair up, departing southern sanctuaries as early as February and arriving at northern locations as the ice melts in May.
CBC Graph
Graph Legend
Annual Population Indices
  • 740,000
  • 740,000
Population Status Trends
Canvasback populations have fluctuated since the 1940s, but declines have been significant since the early 1950s, with the most severe losses in the early 1970s and 1980s. Compared to other ducks, Canvasbacks are fairly scarce; their low numbers have prompted Maryland, Minnesota, Washington, and Wyoming to designate this duck as a “species of conservation concern.” In 2004, the U. S. Fish and Wildlife Service included the Canvasback on its list of “Game Birds Below Desired Condition.”
 
An explanation of the Annual Indices graph displayed to the right can be found here.
Conservation Issues
The Canvasback faces two basic challenges: habitat loss and hunting pressure, especially poaching. In addition, polluted water, shrinking wetlands, dry conditions on the breeding grounds, and disappearing water plants all negatively effect Canvasback populations.
 
From 1951 to 1981, a significant amount of acreage in Alberta, Manitoba, and Saskatchewan was converted to farming and contributed to the destruction of about 40% of this region’s original wetlands. At the same time, drought conditions further shrunk breeding habitat and made nests more accessible to predators. Canvasback populations plummeted. Important Bird Areas have since targeted key staging sites like eastern Lake St. Clare and the lower Detroit River in Michigan, where waterfowl inventories reported near-record lows for Canvasbacks between 2000 and 2004. On the Trempealeau and Upper Mississippi National Wildlife Refuges, Canvasbacks have benefited from management practices aimed at the recovery of wild celery, a primary food source.
 

Hunters provide significant funding for Canvasback conservation, but hunting pressure on this popular duck is still heavy, and management of illegal and incidental shooting has proven difficult.  Long hunting seasons can also interfere with critical weight gain, as Canvasbacks evade hunters or feed at night. Consequently, the U. S. Flyway Councils and the U. S. Fish and Wildlife Service closely monitor populations, limit season lengths, and attempt to educate hunters.

What You Can Do
Join a local field trip to look for Canvasbacks as they migrate through or winter in your area. Escape the northern winter and visit Canvasbacks at the Laguna Atascosa National Wildlife Refuge near Rio Hondo, Texas, where this special duck and other rare and endangered species can be observed in natural habitats.
 
Provide for the protection of and research on Canvasbacks by purchasing a Federal Duck Stamp.
 
For more actions you can take, including Audubon activities, please visit our resources page.
More Information
Visit our resources page for more information about this species.
Natural History References
Kaufman, Kenn. Lives of North American Birds. Houghton Mifflin Company, New York, 1996.
 
Mowbray, T. B. 2002. Canvasback (Aythya valisineria). In The Birds of North America, No. 659 (A. Poole and F. Gill, Eds.). The Birds of North America, Inc., Philadelphia, PA.
 
Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.
Conservation Status References
Chipley, Robert M., George H. Fenwick, Michael J. Parr, and David N. Pashley. The American Bird Conservancy Guide to the 500 Most Important Bird Areas in the United States. New York: Random House, Inc. 2003.
 
Game Birds Below Desired Condition.” 2004. Migratory Bird Status Report. U. S. Fish and Wildlife Service Publication.
 
INDICATOR: Canvasback Population in Lake St. Clair/Detroit River/Western Lake Erie Basin.” Detroit River-Western Lake Erie Basin Indicator Project. U. S. Environmental Protection Agency. Updated 4 December 2006.
 
Kaufman, Kenn. Lives of North American Birds. Houghton Mifflin Company, New York, 1996.
 
Mowbray, T. B. 2002. Canvasback (Aythya valisineria). In The Birds of North America, No. 659 (A. Poole and F. Gill, Eds.). The Birds of North America, Inc., Philadelphia, PA.
 
Sibley, David Allen. The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.