Aythya valisineria

Geographic Range

Canvasbacks breed in the prairie pothole region of central North America, including the United States from Colorado and Nevada north through British Columbia, Alberta, Saskatchewan, Manitoba, the Northwest Territories, the Yukon, and central Alaska. Breeding populations seems to be moving farther northward in recent years. The winter range is from the coastal Pacific Northwest across central prairie states to the southern Great Lakes and south to Florida, Mexico, and Baja California. Largest winter concentrations of canvasbacks are found in Lake St. Clair, the Detroit River and eastern Lake Erie, Puget Sound, San Francisco Bay, the Mississippi River delta, the Chesapeake Bay and Currituck and Pamlico sounds in North Carolina.

• Biogeographic Regions
• nearctic nearctic
  • native native

Habitat

In the breeding season canvasbacks are found in areas with small ponds, slow moving rivers, and dense vegetation. Most breeding occurs in the aspen parklands of central Canada, characterized by aspen woodlands, grasslands, and potholes. Canvasbacks prefer breeding in small lakes and ponds or marshes with dense emergent vegetation, such as cattails ( Typha ), bulrush ( Scirpus acutus ), reeds ( Phragmites communis ), and rivergrass ( Scholochloa festucacea ). During spring and fall migration and winter canvasbacks are found in aquatic areas with high densities of food availability, including estuaries, large freshwater lakes, coastal bays and harbors, and large river deltas. During migration they may also use flooded fields, farm ponds, and wetlands.

• Habitat Regions
• temperate temperate
• saltwater or marine saltwater or marine
• freshwater freshwater

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• coastal coastal
• brackish water brackish water

• Wetlands
• marsh marsh

• Other Habitat Features
• estuarine estuarine

Physical Description

Canvasbacks are sometimes called the "aristocrat of ducks" for their elegant appearance. Canvasbacks are the largest diving duck ( Aythya ) species. Males are slightly larger, from 51 to 56 cm in body length and 863 to 1,589 g mass. Females are from 48 to 52 cm in body length and 908 to 1,543 g in mass. Canvasbacks are distinguished by their large size and characteristic long, sloping profile and wedge-shaped head that is held erect on their long necks. Canvasback breeding plumage, which they keep for most of the year, is striking. Males have rich, reddish-brown heads and necks, black breasts, and white wings, sides, and belly. The rump and tail feathers are black. The feet and legs are dark grey and the bill is black. Female breeding plumage is much more subdued, but similar to males; the head and neck are brownish, the wings, sides, and belly are white or gray, and the tail and breast are dark brown. Non-breeding males and females, and immature individuals, are generally brownish overall. Canvasbacks are sometimes confused with their close relatives: redheads , greater scaup and lesser scaup .

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• male larger
• sexes colored or patterned differently
• male more colorful

Reproduction

Canvasbacks are seasonally monogamous. Courtship begins during the spring migration and continues on the breeding grounds. Males and females generally remain with a partner during the season, although occasional males have extra pair copulations or abandon a first mate for a second. Females use courtship displays to assess male quality, especially male ability to compete for food and space. During the height of courtship, receptive females are periodically surrounded by 3 to 8 males in "courting parties." There are a variety of courtship displays: the neck-stretch, incite behavior, a male sneak approach, kinked-neck, head-throw, and turning the back of the head. All are used to start and enforce the pair bond.

• Mating System
• monogamous monogamous

Females choose the same home ranges for their nesting sites each year. Nests are started as early as late April, but nesting peaks in mid to late May and may continue into June. Pairs lay one brood per year, although they will re-nest if the first brood is destroyed. Nests are built in emergent vegetation above water, although they will occasionally build nests on land as long as it is in a protected area. They prefer medium to large sized, shallow wetlands with extensive emergent vegetation for breeding. Females lay from 5 to 11 smooth, elliptical, greenish drab eggs. Average reported clutch sizes vary regionally, but range from 6.6 to 8.3 eggs per nest. Clutch sizes may be affected by nest parasitism, with parasitized nests having smaller clutches. One egg is laid per day and the female begins to incubate the eggs a few days before the last egg is laid. Eggs are incubated for 24 to 29 days. Young are able to swim and forage soon after hatching. Young fledge at 56 to 68 days after hatching. In late August or September young canvasbacks form groups in preparation for migration. Canvasbacks are capable of breeding in the year after hatching.

Females choose the same home ranges for their nesting sites each year. Nests are started as early as late April, but nesting peaks in mid to late May and may continue into June. Pairs lay one brood per year, although they will re-nest if the first brood is destroyed. Nests are built in emergent vegetation above water, although they will occasionally build nests on land as long as it is in a protected area. They prefer medium to large sized, shallow wetlands with extensive emergent vegetation for breeding. Females lay from 5 to 11 smooth, elliptical, greenish drab eggs. Average reported clutch sizes vary regionally, but range from 6.6 to 8.3 eggs per nest. Clutch sizes may be affected by nest parasitism, with parasitized nests having smaller clutches. One egg is laid per day and the female begins to incubate the eggs a few days before the last egg is laid. Eggs are incubated for 24 to 29 days. Young are able to swim and forage soon after hatching. Young fledge at 56 to 68 days after hatching. In late August or September young canvasbacks form groups in preparation for migration. Canvasbacks are capable of breeding in the year after hatching.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• oviparous oviparous

Females build nests and continue to line them with plants and down feathers throughout the nest-building and incubation period. Male canvasbacks are protective of their mate and the nest, especially in the first week after incubation starts. After that time they begin to spend less time defending the nesting area from predators, other canvasbacks, and redheads . During incubation males abandon their mates and nests. Young are precocial at hatching and are able to swim as soon as their feathers dry. Females brood the young when the weather is cold, however. Within a day after hatching the female and her brood abandon the nest and move into larger bodies of water with abundant emergent vegetation. Females remain with their broods until close to migration. For broods that hatch late in the year, though, that may be at only 2 to 3 weeks old. Females do not feed their young, but they do protect them.

• Parental Investment
• precocial precocial
• pre-fertilization
  • provisioning
  • protecting
    • female
• pre-hatching/birth
  • provisioning
    • female
  • protecting
    • male
    • female
• pre-weaning/fledging
  • protecting
    • female
• pre-independence
  • protecting
    • female

Lifespan/Longevity

The oldest wild canvasback captured was 22 years and 7 months old, the next longest recorded lifespan in a wild canvasback was 16 years 11 months. Annual survival rates for adults have been estimated at 82% for males and 69% for females. Canvasback mortality is documented as a result of hunting, collisions, toxin ingestion, and exposure during cold weather.

Behavior

Canvasbacks are active during the day, they are highly social, and they migrate seasonally between breeding and non-breeding ranges. They migrate in loose V-shaped flocks and are one of the fastest flying ducks. They can fly up to 90 km/hour air speed (115 km/hour ground speed). They have to run along the water for some distance before they can take flight. Canvasbacks are efficient and powerful swimmers, with their legs positioned near the rear of their body. They may spend up to 20% of the day swimming and can dive to over 9 meters deep for 10 to 20 seconds.

• Key Behaviors
• flies
• natatorial natatorial
• diurnal diurnal
• motile motile
• migratory migratory
• social social
• colonial colonial

Home Range

Canvasbacks maintain home ranges during the breeding season that vary in size. In one study, home ranges were about 73 hectares before nesting, increased to about 150 hectares before laying the eggs, and then declined to about 25 hectares when the eggs were laid.

Communication and Perception

Canvasbacks are generally quiet ducks, although they do use a variety of distress calls and emit a variety of coos and rattles as part of courtship behaviors. They use visual signals in courtship, through their displays.

• Communication Channels
• visual visual
• acoustic acoustic

• Perception Channels
• visual visual
• tactile tactile
• acoustic acoustic
• chemical chemical

Food Habits

Canvasbacks are omnivorous and opportunistic. In winter and migration they mainly eat aquatic vegetation, including buds, roots, tubers, and rhizomes. They may also take small snails and clams during this time. In the breeding season canvasbacks eat aquatic plants and animals, including seeds, buds, leaves, rhizomes, tubers, and roots and snails, caddisfly larvae ( Tricoptera ), damselfly and dragonfly nymphs ( Odonata ), mayfly nymphs ( Ephemeroptera ), and midge larvae ( Chironomidae ). Outside of the breeding season canvasbacks forage in small to very large groups (over 1000 individuals) and mainly in the morning and evening. These diving ducks can dive to more than 5 meters depth for 10 to 20 seconds, although they usually dive from 0.5 to 2 meters deep. They take food in a variety of ways, including diving, stripping plants with their feet or beaks, and grabbing prey from the water surface or air. In a dive they use their robust, cone-shaped heads to probe and excavate submerged plants.

The scientific name of canvasbacks comes from their favorite winter food, the aquatic plant Vallisneria americana , or wild celery.

• Primary Diet
• omnivore omnivore

• Animal Foods
• insects
• mollusks

• Plant Foods
• leaves
• roots and tubers
• wood, bark, or stems
• seeds, grains, and nuts

Predation

Canvasback eggs and young are preyed on by a variety of nest predators, including raccoons , striped skunks , red foxes , mink , ermine , American crows , black-billed magpies , common ravens , and California gulls . Adults and fledglings are preyed on by raptors as well as large terrestrial and aquatic predators, including: mink , coyotes , great black-backed gulls , bald eagles , great horned owls , black-crowned night herons , snapping turtles , and northern pike .

When a female notices a predator near her nest, she silently swims away to distract attention. If the young are hatched, the female uses a warning call so that the young swim into thick vegetation. Outside of the breeding season canvasbacks form large groups to help protect against predation. Predation accounts for up to 60% of duckling mortality.

Ecosystem Roles

Canvasbacks form large foraging groups in the non-breeding season, these large numbers of animals feeding on aquatic plants and animals can have a substantial effect on local aquatic ecosystems. Canvasbacks are infected by a variety of diseases and parasites, including renal coccidia ( Eimeria truncata ), malaria ( Plasmodium circumflexum ), blood parasites ( Leucocytozoon simondi and Haemoproteus nettionis ), parasitic trematodes ( Typhlocoelum cucumerinum ), bird fleas ( Ceratophyllus ), bird lice ( Austromenopon leucoxanthum ), and ticks ( Ixodidae and Argasidae ). In some areas canvasbacks are also parasitized by leeches ( Hirudinea ).

Canvasback females may lay their eggs in the nests of other canvasback females, making them intra-specific nest parasites. Canvasbacks are also subject to nest parasitism by redheads ( Aythya americana ) and ruddy ducks ( Oxyura jamaicensis ). Male canvasbacks are important in protecting new nests from nest parasitism, they drive away other species aggressively. Because redheads often lay their eggs in canvasback nests about 1 week after incubation begins, aggressive encounters between canvasbacks and nest parasites at the nest often result in egg loss through breakage. Canvasback eggs are about five times as likely to crack as redhead eggs. Parasitized nests are more likely to be abandoned and ducklings from parasitized nests have lower survival rates than those from non-parasitized nests.

Economic Importance for Humans: Positive

Canvasbacks are important members of healthy, aquatic ecosystems. They are also an important game species and are one of the best studied duck species.

• Positive Impacts
• food food
• research and education

Economic Importance for Humans: Negative

There are no adverse effects of canvasbacks on humans.

Conservation Status

Canvasbacks are protected as migratory gamebirds in the United States, Mexico, and Canada. They are not considered threatened or endangered currently. Populations are affected by hunting pressure, habitat degradation, pollution, and collisions with cars or stationary objects. Hunting pressure is most intense during fall migration. In 1999 approximately 87,000 canvasbacks were taken by U.S. hunters. Because canvasbacks eat vegetation in aquatic sediments, they are susceptible to the toxins that accumulate in those sediments. This is particularly true in areas of high industrial activity, such as the Detroit River.

Additional Links

Encyclopedia of Life

BioKIDS Critter Catalog

Contributors

Tanya Dewey (author), Animal Diversity Web.

References

Mowbray, T. 2002. Canvasbacks, Aythya valisineria. The Birds of North America Online , 659: 1-20. Accessed December 05, 2008 at http://bna.birds.cornell.edu/bna/species/659 .