Animal Diversity Web

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. (Mow­bray, 2002)

• Biogeographic Regions
• nearctic
  • 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. (Mow­bray, 2002)

• Habitat Regions
• temperate
• saltwater or marine
• freshwater

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

• Wetlands
• marsh

• Other Habitat Features
• 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. (Mow­bray, 2002)

• Other Physical Features
• endothermic
• homoiothermic
• bilateral symmetry

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

• Range mass

  863 to 1589 g

  30.41 to 56.00 oz

• Range length

  48 to 56 cm

  18.90 to 22.05 in

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. (Mow­bray, 2002)

• 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. (Mow­bray, 2002)

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
• seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• oviparous

• 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

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. (Mow­bray, 2002)

• 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

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. (Mow­bray, 2002)

• Range lifespan
  Status: wild

  22.6 (high) years

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
• diurnal
• motile
• migratory
• social
• 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. (Mow­bray, 2002)

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. (Mow­bray, 2002)

• Communication Channels
• visual
• acoustic

• Perception Channels
• visual
• tactile
• acoustic
• 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. (Mow­bray, 2002)

The sci­en­tific name of can­vas­backs comes from their fa­vorite win­ter food, the aquatic plant Val­lis­ne­ria amer­i­cana, or wild cel­ery. (Mow­bray, 2002)

• Primary Diet
• 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. (Mow­bray, 2002)

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. (Mow­bray, 2002)

• Known Predators

  • raccoons (Procyon lotor)
  • striped skunks (Mephitis mephitis)
  • red foxes (Vulpes vulpes)
  • mink (Neovison vison)
  • ermine (Mustela erminea)
  • American crows (Corvus brachyrhynchos)
  • black-billed magpies (Pica hudsonia)
  • common ravens (Corvus corax)
  • California gulls (Larus californicus)
  • coyotes (Canis latrans)
  • great black-backed gulls (Larus marinus)
  • bald eagles (Haliaeetus leucocephalus)
  • great horned owls (Bubo virginianus)
  • black-crowned night herons (Nycticorax nycticorax)
  • snapping turtles (Chelydra serpentina)
  • northern pike (Esox lucius)

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). (Mow­bray, 2002)

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. (Mow­bray, 2002)

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. (Mow­bray, 2002)

• Positive Impacts
• 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. (Mow­bray, 2002)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Migratory Bird Act

  Protected

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

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.