The canvasback (''Aythya valisineria'') is a species of
diving duck
The diving ducks, commonly called pochards or scaups, are a category of duck which feed by diving beneath the surface of the water. They are part of Anatidae, the diverse and very large family that includes ducks, geese, and swans.
The diving d ...
, the largest found in North America.
Taxonomy
Scottish-American naturalist
Alexander Wilson described the canvasback in 1814. The genus name is derived from
Greek
Greek may refer to:
Greece
Anything of, from, or related to Greece, a country in Southern Europe:
*Greeks, an ethnic group.
*Greek language, a branch of the Indo-European language family.
**Proto-Greek language, the assumed last common ancestor ...
''aithuia'', an unidentified
seabird
Seabirds (also known as marine birds) are birds that are adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same enviro ...
mentioned by authors, including
Hesychius and
Aristotle
Aristotle (; grc-gre, Ἀριστοτέλης ''Aristotélēs'', ; 384–322 BC) was a Greek philosopher and polymath during the Classical period in Ancient Greece. Taught by Plato, he was the founder of the Peripatetic school of ph ...
.
The species name ''valisineria'' comes from the wild celery ''
Vallisneria americana
''Vallisneria americana'', commonly called wild celery, water-celery, tape grass, or eelgrass, is a plant in the family Hydrocharitaceae, the "tape-grasses". ''V. americana'' is a fresh water species that can tolerate salt, living in salinitie ...
'', whose winter
bud
In botany, a bud is an undeveloped or embryonic shoot and normally occurs in the axil of a leaf or at the tip of a stem. Once formed, a bud may remain for some time in a dormant condition, or it may form a shoot immediately. Buds may be spec ...
s and
rhizomes are the canvasback's preferred food during the nonbreeding period.
The celery genus is itself named for seventeenth century Italian botanist
Antonio Vallisneri
Antonio Vallisneri ( Trassilico,3 May 1661 – Padua, 18 January 1730), also rendered as ''Antonio Vallisnieri'', was an Italian medical scientist, physician and naturalist.
Life
Vallisneri was born in Trassilico, a small village in Garfagnana, ...
.
[
The duck's common name is based on early European inhabitants of North America's assertion that its back was a canvas-like color.] In other languages it is just a ''white-backed duck''; for example in French, ''morillon à dos blanc'', or Spanish
Spanish might refer to:
* Items from or related to Spain:
**Spaniards are a nation and ethnic group indigenous to Spain
**Spanish language, spoken in Spain and many Latin American countries
**Spanish cuisine
Other places
* Spanish, Ontario, Can ...
, ''pato lomo blanco''. In Mexico
Mexico (Spanish: México), officially the United Mexican States, is a country in the southern portion of North America. It is bordered to the north by the United States; to the south and west by the Pacific Ocean; to the southeast by Guatema ...
it is called ''pato coacoxtle''.
Description
It ranges from in length and weighs , with a wingspan of . It is the largest species in the genus ''Aythya
''Aythya'' is a genus of diving ducks. It has twelve described species. The name ''Aythya'' comes from the Ancient Greek word (), which may have referred to a sea-dwelling duck or an auklet.
''Aythya shihuibas'' was described from the Late Mi ...
'', 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 and 54 females there averaged .[''CRC Handbook of Avian Body Masses, 2nd Edition'' by John B. Dunning Jr. (Editor). CRC Press (2008), .] 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. The bill is blackish and the legs and feet are bluish-gray. The iris
Iris most often refers to:
*Iris (anatomy), part of the eye
*Iris (mythology), a Greek goddess
* ''Iris'' (plant), a genus of flowering plants
* Iris (color), an ambiguous color term
Iris or IRIS may also refer to:
Arts and media
Fictional ent ...
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.
Breeding
The breeding habitat of the canvasback is in North American prairie pothole
The Prairie Pothole Region (PPR; french: Région des cuvettes/fondrières des prairies) is an expansive area of the northern Great Plains that contains thousands of shallow wetlands known as potholes. These potholes are the result of glacier ac ...
s. The bulky nest is built from vegetation in a marsh
A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found a ...
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.[ It prefers to nest over water on permanent prairie marshes surrounded by emergent vegetation, such as ]cattails
''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in ...
and bulrushes
Bulrush is a vernacular name for several large wetland graminoid, grass-like plants
*Sedge family (Cyperaceae):
**''Cyperus''
**''Scirpus''
**''Blysmus''
**''Bolboschoenus''
**''Scirpoides''
**''Isolepis''
**''Schoenoplectus''
**''Trichophorum''
...
, which provide protective cover. Other important breeding areas are the subarctic river deltas in Saskatchewan
Saskatchewan ( ; ) is a province in western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on the south by the U.S. states of Montana and North Dak ...
and the interior of Alaska
Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S. ...
.
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. The canvasback sometimes lays its eggs in other canvasback nests and redheads often parasitize canvasback nests.
Migration
The canvasback migrates through the Mississippi Flyway
The Mississippi Flyway is a bird migration route that generally follows the Mississippi, Missouri, and Lower Ohio Rivers in the United States across the western Great Lakes to the Mackenzie River and Hudson Bay in Canada. The main endpoints of ...
to wintering grounds in the mid-Atlantic United States and the Lower Mississippi Alluvial Valley (LMAV), or the Pacific Flyway
The Pacific Flyway is a major north-south flyway for migratory birds in the Americas, extending from Alaska to Patagonia. Every year, migratory birds travel some or all of this distance both in spring and in fall, following food sources, heading ...
to wintering grounds along the coast of California
California is a state in the Western United States, located along the Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the most populous U.S. state and the 3rd largest by area. It is also the m ...
. Historically, the Chesapeake Bay
The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
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
Brackish water, sometimes termed brack water, is water occurring in a natural environment that has more salinity than freshwater, but not as much as seawater. It may result from mixing seawater (salt water) and fresh water together, as in estu ...
estuarine bays and marshes with abundant submergent vegetation and invertebrates
Invertebrates are a paraphyletic group of animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This is a grouping including all animals apart from the chordat ...
are ideal wintering habitat for canvasbacks.[ A small number of birds are also known to have crossed the Atlantic, with several sightings being recorded in the ]United Kingdom
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the European mainland, continental mainland. It comprises England, Scotlan ...
. In December 1996, a canvasback was observed in a quarry in Kent
Kent is a county in South East England and one of the home counties. It borders Greater London to the north-west, Surrey to the west and East Sussex to the south-west, and Essex to the north across the estuary of the River Thames; it faces ...
, which was followed by an additional sighting in Norfolk
Norfolk () is a ceremonial and non-metropolitan county in East Anglia in England. It borders Lincolnshire to the north-west, Cambridgeshire to the west and south-west, and Suffolk to the south. Its northern and eastern boundaries are the No ...
in January 1997. At least five more sightings have since been confirmed in England.
Diet
The canvasback feeds mainly by diving, sometimes dabbling, mostly eating seeds, buds, leaves, tubers, roots, snails, and insect larvae.[ 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. 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.][SAV… It’s What’s for Dinner, Developed by Martha Shaum, Aquatic Resources Education Program, Maryland Department of Natural Resources]
In the early 1950s it was estimated that there were 225,000 canvasbacks wintering in the Chesapeake Bay
The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
; 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.[ 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.
]
Cuisine
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
Maryland ( ) is a state in the Mid-Atlantic region of the United States. It shares borders with Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware and the Atlantic Ocean to ...
and Chesapeake Bay
The Chesapeake Bay ( ) is the largest estuary in the United States. The Bay is located in the Mid-Atlantic region and is primarily separated from the Atlantic Ocean by the Delmarva Peninsula (including the parts: the Eastern Shore of Maryland / ...
, 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".
Edith Wharton refers to canvasback with blackcurrant sauce as an especially luxurious dinner served in New York City
New York, often called New York City or NYC, is the most populous city in the United States. With a 2020 population of 8,804,190 distributed over , New York City is also the most densely populated major city in the Un ...
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".[Paul Freedman, "Terrapin Monster", p. 51-64 of Dina Khapaeva, ed., ''Man-Eating Monsters: Anthropocentrism and Popular Culture'', , p. 59]
Conservation
Populations have fluctuated widely. Low levels in the 1980s put the canvasback on lists of special concern, but numbers increased greatly in the 1990s. The canvasback is particularly vulnerable to drought and wetland drainage on the prairies of North America.
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. Protecting key feeding and breeding grounds is key for conserving many types of migratory birds.
References
External links
Canvasback - ''Aythya valisineria''
- USGS Patuxent Bird Identification InfoCenter
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{{Taxonbar, from=Q378533
Aythya
Native birds of Alaska
Native birds of Western Canada
Native birds of the Canadian Prairies
Native birds of the Northwestern United States
Birds described in 1814
Taxa named by Alexander Wilson (ornithologist)
Extant Pleistocene first appearances