Editing Canvasback

{{Short description|Species of bird}}
{{Speciesbox
| name = Canvasback
| fossil_range = {{Fossil range|Pleistocene|present}}
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |date=2016 |title=''Aythya valisineria'' |volume=2016 |page=e.T22680364A92858752 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22680364A92858752.en |access-date=12 November 2021}}</ref>
| image = Aythya_valisineria_at_Las_Gallinas_Wildlife_Ponds.jpg
| image_caption = Male
| image2 = Aythya valisineria2.jpg
| image2_caption = Female with ducklings
| genus = Aythya
| species = valisineria
| authority = ([[Alexander Wilson (ornithologist)|Wilson]], 1814)
| synonyms =
''Aythya vallisneria'' <small>(''[[lapsus]]'')</small>
| range_map = Aythya valisineria map.svg
|range_map_caption={{legend|#FF7F2A|Breeding}}{{legend|#FFDD55|Migration}}{{legend|#7137C8|Year-round}}{{legend|#5F8DD3|Nonbreeding}}
}}
{{birdsong|url=https://xeno-canto.org/species/Aythya-valisineria|species=Canvasback}}

The '''canvasback''' ('''''Aythya valisineria''''') is a species of [[diving duck]], the largest found in North America.

==Taxonomy==
Scottish-American naturalist [[Alexander Wilson (ornithologist)|Alexander Wilson]] described the canvasback in 1814. The genus name is derived from [[Greek language|Greek]] ''aithuia'', an unidentified [[seabird]] mentioned by authors, including [[Hesychius of Miletus|Hesychius]] and [[Aristotle]].<ref name= job90>{{cite book | last= Jobling | first= James A | year= 2010| title= The Helm Dictionary of Scientific Bird Names | url= https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling | publisher = Christopher Helm | location = London | isbn = 978-1-4081-2501-4 |pages = [https://archive.org/details/Helm_Dictionary_of_Scientific_Bird_Names_by_James_A._Jobling/page/n64 64], 398}}</ref>
The species name ''valisineria'' comes from the wild celery ''[[Vallisneria americana]]'', whose winter [[bud]]s and [[rhizome]]s are the canvasback's preferred food during the nonbreeding period.<ref name=aab>{{Cite AllAboutBirds|Canvasback}}</ref> The celery genus is itself named for seventeenth century Italian botanist [[Antonio Vallisneri]].<ref name= job90/>

The duck's common name is based on early European inhabitants of North America's assertion that its back was a [[canvas]]-like color.<ref name=define>{{Dictionary.com|Canvasback}}</ref> In other languages it is just a ''white-backed duck''; for example in [[French language|French]], ''morillon à dos blanc'', or [[Spanish language|Spanish]], ''pato lomo blanco''.<ref name="avibase">{{avibase|1929E1E16E073570|Aythya valisineria}}</ref> In [[Mexico]] it is called ''pato coacoxtle''.<ref>{{Cite web|url=https://www.audubon.org/es/guia-de-aves/ave/pato-coacoxtle|title = Pato Coacoxtle|date = 15 December 2015}}</ref>

==Description==
It ranges from {{convert|48|–|56|cm|in|abbr=on}} in length and weighs {{convert|862|–|1588|g|lb|abbr=on}}, with a wingspan of {{convert|79|–|89|cm|in|abbr=on}}.<ref>{{Cite web |title=Canvasback Identification, All About Birds, Cornell Lab of Ornithology |url=https://www.allaboutbirds.org/guide/Canvasback/id |access-date=2025-02-06 |website=www.allaboutbirds.org |language=en}}</ref> It is the largest species in the genus ''[[Aythya]]'',{{Citation needed|date=February 2025}} and the largest diving duck in North America.<ref>{{Cite web |title=Canvasback |url=https://abcbirds.org/bird/canvasback/ |access-date=6 February 2025 |website=American Bird Conservancy}}</ref> Canvasbacks are similar in size to a [[mallard]] but with a heavier and more compact build. 191 males wintering in western [[New York (state)|New York]] averaged {{convert|1252|g|lb|abbr=on}} and 54 females there averaged {{convert|1154|g|lb|abbr=on}}.<ref name = "CRC">''CRC Handbook of Avian Body Masses, 2nd Edition'' by John B. Dunning Jr. (Editor). CRC Press (2008), {{ISBN|978-1-4200-6444-5}}.</ref> 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.<ref name=DUCB>{{cite web |url=http://www.ducks.org/hunting/waterfowl-id/canvasback |title=Canvasback |publisher=[[Ducks Unlimited]] |access-date = 23 November 2009}}</ref> The bill is blackish and the legs and feet are bluish-gray. The [[Iris (anatomy)|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.<ref name="DUCB"/>

==Breeding==
The breeding habitat of the canvasback is in [[North America]]n [[prairie pothole]]s. The bulky nest is built from vegetation in a [[marsh]] and lined with [[Down feather|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.<ref name=aab/> It prefers to nest over water on permanent prairie marshes surrounded by emergent vegetation, such as [[Typha|cattails]] and [[Schoenoplectus|bulrushes]], which provide protective cover. Other important breeding areas are the [[subarctic]] river deltas in [[Saskatchewan]] and the interior of [[Alaska]].<ref name="DUCB"/>

It has a clutch size of approximately 5–11&nbsp;eggs, which are greenish drab. The chicks are covered in down at hatching and able to leave the nest soon after.<ref name="aab"/> The canvasback sometimes lays its eggs in other canvasback nests and [[Redhead (duck)|redheads]] often [[Brood parasite|parasitize]] canvasback nests.<ref name="DUCB"/>
[[File:Canvasaback (Aythya valisineria) RWD2.jpg|thumb|left|Drake canvasback stretching wings]]

==Migration==
The canvasback migrates through the [[Mississippi Flyway]] to wintering grounds in the mid-Atlantic United States and the [[Lower Mississippi River|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]] [[Estuary|estuarine]] bays and marshes with abundant submergent vegetation and [[invertebrates]] are ideal wintering habitat for canvasbacks.<ref name=DUCB/> 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.<ref name=BritishBirds>{{cite journal|last=Larkin|first=Paul|author2=Mercer, David|title=Canvasback in Kent: new to Britain|journal=British Birds|date=March 2004|volume=97|pages=139–144|issn=0007-0335}}</ref>

==Diet==
[[File:Tubers.jpg|thumb|Tubers of [[Stuckenia pectinata|Sago Pondweed]] (''Stuckenia pectinata''), a favorite food of the canvasback]]
The canvasback feeds mainly by diving, sometimes dabbling, mostly eating seeds, buds, leaves, tubers, roots, snails, and insect larvae.<ref name=aab/> Besides its namesake, wild celery, the canvasback shows a preference for the tubers of [[Stuckenia pectinata|sago pondweed]], which can make up 100% of its diet at times.<ref>[http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=222000377 Flora of North America: ''Stuckenia pectinata'']</ref> 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.<ref name=dnr>[http://www.dnr.state.md.us/bay/sav/bgic/download/SAV%20It's%20What's%20for%20Dinner.pdf SAV… It’s What’s for Dinner, Developed by Martha Shaum, Aquatic Resources Education Program, Maryland Department of Natural Resources]  {{webarchive|url=https://web.archive.org/web/20110419212353/http://www.dnr.state.md.us/bay/sav/bgic/download/SAV%20It%27s%20What%27s%20for%20Dinner.pdf |date=April 19, 2011 }}</ref> 
[[File:Canvas back duck diving.webm|thumb|Canvasback duck diving]]
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 America]]n 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 sub-aquatic vegetation 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 [[Macoma balthica|Baltic Clams]], which are very common in the Chesapeake Bay: the ducks have been able to adapt to the decline in sub-aquatic vegetation by changing their diet. [[Redhead (duck)|Redheads]], which also feed on the tubers of sub-aquatic vegetation, have not been able to adapt, and their population remains low.<ref name=dnr/>

==Cuisine==

Canvasback ducks were a particularly prestigious [[game (hunting)|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".<ref>Paul Freedman, "American Restaurants and Cuisine in the Mid-Nineteenth Century", ''The New England Quarterly'' '''84''':1:5-59 (March 2011), {{doi|10.1162/TNEQ_a_00066}}, pp. 36, 39</ref>

[[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".<ref>Paul Freedman, "Terrapin Monster", p. 51–64 of Dina Khapaeva, ed., ''Man-Eating Monsters: Anthropocentrism and Popular Culture'', {{isbn|9781787695283}}, p. 59</ref>

==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.<ref name=BNA>{{cite book |last=Mowbray |first=T. B. |editor1-last=Poole |editor1-first=A. |editor2-last=Gill |editor2-first=F. |title=The Birds of North America |chapter=Canvasback (''Aythya valisineria'') |number=659 |volume=17 |year=2002 |location=Philadelphia, PA |publisher=The Birds of North America, Inc.}}</ref> The canvasback is particularly vulnerable to drought and wetland drainage on the prairies of North America.<ref name="DUCB"/>

Many species of ducks, including the canvasback, are highly [[Bird migration|migratory]], but are effectively conserved by protecting the places where they nest, even though they may be hunted away from their breeding grounds.<ref name="iucn status 12 November 2021" /> Protecting key feeding and breeding grounds is key for conserving many types of migratory birds.{{Citation needed|date=January 2021}}

== References ==
{{Reflist}}

==External links==
{{Commons category|Aythya valisineria}}
{{Wikispecies|Aythya valisineria}}
* [http://www.mbr-pwrc.usgs.gov/id/framlst/i1470id.html Canvasback - ''Aythya valisineria''] - USGS Patuxent Bird Identification InfoCenter
* {{InternetBirdCollection|canvasback-aythya-valisineria|Canvasback}}
* {{VIREO|Canvasback|Canvasback}}
* {{IUCN_Map|22680364/137943278|Aythya valisineria}}
* {{cite journal | last=Mowbray | first=Thomas B. | editor1-first=Alan F | editor1-last=Poole | editor2-first=Frank B | editor2-last=Gill | title=Canvasback (''Aythya valisineria'') | journal=Birds of the World | publisher=[[Cornell Lab of Ornithology]] | date=2020-03-04 | doi=10.2173/bow.canvas.01 | s2cid=216414904 | url=http://birdsoftheworld.org/bow/species/canvas/cur/introduction | access-date=2021-04-20| url-access=subscription }}

{{North American Game}}

{{Taxonbar|from=Q378533}}
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[[Category:Aythya]]
[[Category:Native birds of Alaska]]
[[Category:Native birds of Western Canada]]
[[Category:Native birds of the Canadian Prairies]]
[[Category:Native birds of the Northwestern United States]]
[[Category:Birds described in 1814]]
[[Category:Taxa named by Alexander Wilson (ornithologist)]]
[[Category:Extant Pleistocene first appearances]]