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.
Range mass: 863 to 1589 g.
Range length: 48 to 56 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; sexes colored or patterned differently; male more colorful
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.
Range lifespan
Status: wild: 22.6 (high) years.
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 ; saltwater or marine ; freshwater
Aquatic Biomes: lakes and ponds; rivers and streams; coastal ; brackish water
Wetlands: marsh
Other Habitat Features: estuarine
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 (Native )
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.
Animal Foods: insects; mollusks
Plant Foods: leaves; roots and tubers; wood, bark, or stems; seeds, grains, and nuts
Primary Diet: omnivore
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.
Commensal/Parasitic Species:
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 ; research and education
There are no adverse effects of canvasbacks on humans.
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.
US Migratory Bird Act: protected
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
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 ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
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.
Known Predators:
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
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.
Breeding interval: Canvasbacks breed once yearly.
Breeding season: Canvasbacks nest from April to June, with a peak in mid to late May.
Range eggs per season: 5 to 11.
Range time to hatching: 24 to 29 days.
Average time to hatching: 25 days.
Range fledging age: 56 to 68 days.
Average age at sexual or reproductive maturity (female): 1 years.
Average age at sexual or reproductive maturity (male): 1 years.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; 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 ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Protecting: Female); pre-independence (Protecting: Female)
Although this duck’s rufous-red is one of its most striking field marks, the male Canvasback is not the only duck in North America with this pattern of coloration. In many parts of its range, this species occurs side by side with the closely-related Redhead (Aythya americana), and a couple field marks must be noted in order to distinguish the two. The Canvasback is slightly larger (20-24 inches), has a longer bill, and is much lighter on the back and flanks. Males have a red head and white body (resembling a sheet of blank canvas from a distance), while females are mostly light grayish-brown. The Canvasback breeds primarily in the northern Great Plains, the northern Rockies, western Canada, and Alaska. Most Canvasback populations migrate south in winter to the southern two-thirds of the United States and into Mexico. In its wintering range, this species is more common inland than the Redhead. Canvasbacks breed in lakes, ponds, marshes and bays. In winter, this species utilizes similar habitats as it does during the breeding season. In summer, Canvasbacks eat both aquatic plants and animals, such as small insects and mollusks; in winter, they feed primarily on plant matter, particularly the wild celery plant (Vallisneria americana) from which this species derives its scientific name. One of several species of “diving ducks” in North America, Redheads may be observed submerging themselves to feed on aquatic plant matter. In winter, they may also be observed in large flocks on coastal bays and lagoons. This species is primarily active during the day.
Although this duck’s rufous-red is one of its most striking field marks, the male Canvasback is not the only duck in North America with this pattern of coloration. In many parts of its range, this species occurs side by side with the closely-related Redhead (Aythya americana), and a couple field marks must be noted in order to distinguish the two. The Canvasback is slightly larger (20-24 inches), has a longer bill, and is much lighter on the back and flanks. Males have a red head and white body (resembling a sheet of blank canvas from a distance), while females are mostly light grayish-brown. The Canvasback breeds primarily in the northern Great Plains, the northern Rockies, western Canada, and Alaska. Most Canvasback populations migrate south in winter to the southern two-thirds of the United States and into Mexico. In its wintering range, this species is more common inland than the Redhead. Canvasbacks breed in lakes, ponds, marshes and bays. In winter, this species utilizes similar habitats as it does during the breeding season. In summer, Canvasbacks eat both aquatic plants and animals, such as small insects and mollusks; in winter, they feed primarily on plant matter, particularly the wild celery plant (Vallisneria americana) from which this species derives its scientific name. One of several species of “diving ducks” in North America, Redheads may be observed submerging themselves to feed on aquatic plant matter. In winter, they may also be observed in large flocks on coastal bays and lagoons. This species is primarily active during the day.
The canvasback (Aythya valisineria) is a species of diving duck, the largest found in North America.
Scottish-American naturalist Alexander Wilson described the canvasback in 1814. The genus name is derived from Greek aithuia, an unidentified seabird mentioned by authors, including Hesychius and Aristotle.[2] The species name valisineria comes from the wild celery Vallisneria americana, whose winter buds and rhizomes are the canvasback's preferred food during the nonbreeding period.[3] The celery genus is itself named for seventeenth century Italian botanist Antonio Vallisneri.[2]
The duck's common name is based on early European inhabitants of North America's assertion that its back was a canvas-like color.[4] In other languages it is just a white-backed duck; for example in French, morillon à dos blanc, or Spanish, pato lomo blanco.[5] In Mexico it is called pato coacoxtle.[6]
It ranges from 48–56 cm (19–22 in) in length and weighs 862–1,600 g (1.900–3.527 lb), with a wingspan of 79–89 cm (31–35 in). It is the largest species in the genus Aythya, being similar in size to a mallard but with a heavier and more compact build than it. 191 males wintering in western New York averaged 1,252 g (2.760 lb) and 54 females there averaged 1,154 g (2.544 lb).[7] The canvasback has a distinctive wedge-shaped head and long graceful neck. The adult male (drake) has a black bill, a chestnut red head and neck, a black breast, a grayish back, black rump, and a blackish brown tail. The drake's sides, back, and belly are white with fine vermiculation resembling the weave of a canvas, which gave rise to the bird's common name.[8] 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. The adult female (hen) also has a black bill, 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. Its sloping profile distinguishes it from other ducks.[8]
The breeding habitat of the canvasback is in North American prairie potholes. The bulky nest is built from vegetation in a marsh and lined with down. Loss of nesting habitat has caused populations to decline. The canvasback usually takes a new mate each year, pairing in late winter on ocean bays.[3] It prefers 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 subarctic river deltas in Saskatchewan and the interior of Alaska.[8]
It has a clutch size of approximately 5–11 eggs, which are greenish drab. The chicks are covered in down at hatching and able to leave the nest soon after.[3] The canvasback sometimes lays its eggs in other canvasback nests and redheads often parasitize canvasback nests.[8]
The canvasback migrates 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 (SAV) in the bay, their range has shifted south towards the LMAV. Brackish estuarine bays and marshes with abundant submergent vegetation and invertebrates are ideal wintering habitat for canvasbacks.[8] A small number of birds are also known to have crossed the Atlantic, with several sightings being recorded in the United Kingdom. In December 1996, a canvasback was observed in a quarry in Kent, which was followed by an additional sighting in Norfolk in January 1997. At least five more sightings have since been confirmed in England.[9]
The canvasback feeds mainly by diving, sometimes dabbling, mostly eating seeds, buds, leaves, tubers, roots, snails, and insect larvae.[3] Besides its namesake, wild celery, the canvasback shows a preference for the tubers of sago pondweed, which can make up 100% of its diet at times.[10] The canvasback has large webbed feet adapted for diving and its bill helps it dig tubers from the substrate. In the late 1930s, studies showed that four-fifths of the food eaten by canvasbacks was plant material.[11]
In the early 1950s it was estimated that there were 225,000 canvasbacks wintering in the Chesapeake Bay; this represented one-half of the entire North American population. By 1985, there were only 50,000 ducks wintering there, or one-tenth of the population. Canvasbacks were extensively hunted around the start of the 20th century, but federal hunting regulations now restrict their harvest, so hunting is ruled out as a cause for the decline. Scientists have now concluded that the decline in duck populations was due to the decline in SAV acreage. Today the population has stabilized and is even increasing slightly, although it is nowhere near previous levels. Studies have now shown that by the 1970s four-fifths of the ducks' diet was made 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.[11] 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.
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".[12]
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".[13]
Populations have fluctuated widely. Low levels in the 1980s put the canvasback on lists of special concern, but numbers increased greatly in the 1990s.[14] The canvasback is particularly vulnerable to drought and wetland drainage on the prairies of North America.[8]
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.[1] Protecting key feeding and breeding grounds is key for conserving many types of migratory birds.
The canvasback (Aythya valisineria) is a species of diving duck, the largest found in North America.
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