View source for Lesser scaup

{{Short description|Species of bird}}
{{Speciesbox
| image = Drake Lesser Scaup (Aythya affinis) Barengat Inlet, New Jersey, USA.jpg
| image2 = Hen Lesser Scaup (Aythya affinis), Barnegat Inlet, New Jersey, USA.jpg
| image_caption = Adult male
| image2_caption = Adult female
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="iucn status 12 November 2021">{{cite iucn |author=BirdLife International |date=2016 |title=''Aythya affinis'' |volume=2016 |article-number=e.T22680402A92861095 |doi=10.2305/IUCN.UK.2016-3.RLTS.T22680402A92861095.en |access-date=12 November 2021}}</ref>
| genus = Aythya
| species = affinis
| authority = ([[Thomas Campbell Eyton|Eyton]], 1838)
| synonyms =
''Fuligula affinis'' <small>Eyton, 1838</small>
| range_map = Aythya affinis 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-affinis|species=Lesser Scaup}}

The '''lesser scaup''' ('''''Aythya affinis''''') is a small [[North America]]n [[diving duck]] that migrates south as far as [[Central America]] in winter. It is colloquially known as the '''little bluebill''' or '''broadbill''' because of its distinctive blue bill. The origin of the name scaup may stem from the bird's preference for feeding on scalp—the Scottish word for clams, oysters, and mussels; however, some credit it to the female's discordant scaup call as the name's source.<ref name=DUb/> It is apparently a very close relative of the [[Holarctic]] [[greater scaup]] or "bluebill" (''A. marila''), with which it forms a [[superspecies]].<ref name = carboneras1992 /><ref name=Livezey/> The scientific name is derived from [[Ancient Greek]] and [[Latin]], with ''aithuia'' being an Ancient Greek term for an unidentified [[seabird]], used by [[Hesychius of Miletus|Hesychius]] and [[Aristotle]], among other authors, and ''affinis'', Latin for "related to", from the lesser scaup's resemblance to the greater scaup.<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/n35 35], 64}}</ref>

==Description==
Adults are {{convert|38|-|48|cm|in|abbr=on}} long, {{convert|41.7|-|43|cm|in|abbr=on}} on average. The species can weigh {{convert|454|-|1089|g|lb|abbr=on}}; males weigh {{convert|820|g|lb|abbr=on}} on average while females weigh noticeably less, at {{convert|730|g|lb|abbr=on}} on average.<ref name= Cornell/> Wing lengths (not [[wingspan]]s) are about {{convert|7.5|-|7.9|in|cm|abbr=on}} in males and {{convert|7.3|-|7.8|in|cm|abbr=on}} in females. The [[Tarsus (skeleton)|tarsus]] is about {{convert|1.4|-|1.5|in|cm|abbr=on}} long, and the bill is {{convert|1.4|-|1.7|in|cm|abbr=on}}.<ref name=DUb/><ref name = carboneras1992 /><ref name = Madge/><ref name=DUa/> The wingspan is {{convert|68|-|78|cm|in|abbr=on}}.<ref name= Cornell/>

The adult males (drakes) in [[Plumage|definitive basic (breeding) plumage]] have a black, iridescent head and a small tuft at the hindcrown, a black breast, a whitish-grey back, wings with darker [[vermiculation]]s and black outer and greyish-brown inner primary [[remiges]]. The underparts are white with some [[olive (color)|olive]] vermiculations on the flanks, and the [[rectrices]] and tail coverts are black. Adult females (hens) have a white band at the base of the bill and often a lighter ear region, and are otherwise dark brown all over, shading to white on the mid-belly. Drakes in [[eclipse plumage]] look similar, but with a very dark head and breast, little or no white on the head and usually some greyish vermiculations on the wings. Immature birds resemble the adult females, but are duller and have hardly any white at the bill base. Both sexes have white secondary remiges, a blue-grey bill with a smallblack "nail" at the tip and grey feet; the drakes have a bright yellow [[iris (anatomy)|iris]], while that of females is orange to yellow varying with age<ref>{{Cite journal|last=Trauger|first=David L.|date=1 April 1974|title=Eye Color of Female Lesser Scaup in Relation to Age|url=https://sora.unm.edu/sites/default/files/journals/auk/v091n02/p0243-p0254.pdf|journal=The Auk|volume=91|issue=2|pages=243–254}}</ref> and that of immatures is brown. [[Down feather|Downy]] hatchlings look much like those of related species, with dark brown upperparts and pale [[buff (color)|buff]] underparts, chin, [[supercilium]] and back spots.<ref name=DUb/><ref name = carboneras1992 /><ref name = Madge/><ref name=DUa/>

These birds are not very vocal, at least compared to [[dabbling duck]]s. Hens give the namesake discordant ''scaup, scaup'' call; in courtship drakes produce weak whistles. Hens vocalize more often than those of the [[greater scaup]]—particularly during flight—but their call is weaker, a guttural ''brrtt, brrtt''.<ref name=DUb/><ref name=Madge/><ref name=DUa/>

===Identification===
<gallery>
File:Lesser Scaup 2.jpg|Lesser scaup drake in basic plumage. Note typical head shape; purple sheen visible on neck.
File:Greater scaup male.jpg|Greater scaup drake in basic plumage. Note typical head shape; green sheen visible on neck.
File:Aythya affinis.JPG|Lesser scaup hen.
File:Greater scaup female.jpg|Greater scaup hen.
</gallery>

Lesser scaup are often hard to distinguish from the [[greater scaup]] when direct comparison is not possible, but in North America a large [[Aythya|scaup]] flock will often have both species present. Females, juveniles and drakes in eclipse plumage are hard to identify; there is considerable overlap in length between the two species, but greater scaup are usually noticeably more bulky. Lesser scaup females and immatures tend to have less white around the bill, but this too varies considerably between individual birds. Lesser Scaup generally have a smaller and straighter bill, with a relatively narrow profile, while Greater Scaup have a wider, more spatulate profile toward the tip of the bill. The dark nail tip averages wider on Greater Scaup.<ref>{{Cite book|last=Sibley|first=David|title=The Sibley guide to birds|date=2014|others=Scott & Nix|isbn=978-0-307-95790-0|edition=2|location=New York|oclc=869807502}}</ref> In flight, the most tell-tale sign is the white secondary [[remiges]], whereas in the greater scaup the white extends on the primary remiges also, i.e. far towards the wingtip.<ref name=DUb/><ref name = carboneras1992 /><ref name = Madge/><ref name=DUa/> 

Lesser scaup drakes in nuptial plumage are often said to be recognizable by the purple instead of green sheen of the head and a darker back. But this is unreliable because it varies according to light conditions, and these birds are often too far away from the observer to make out any sheen at all.  The shape of the head is a crucial difference, but only when birds are at rest and not actively diving. In the greater scaup drake, the forehead is usually quite massive (especially in North American and East Asian populations), whereas the nape presents a smooth shallow curve and may appear almost straightly sloping. The lesser scaup drake presents the opposite shape, with a less bulging forehead and a nape that looks strongly curved or even angular due to the small crest. When the birds raise their heads, these differences are most easy to spot, and after observing the two species in direct comparison it usually becomes easy to recognize. In fact, in basic plumage the lesser scaup drake may appear identical in shape and size to a drake of the [[ring-necked duck]] (''A. collaris''); the black back and wings of that species are hard to confuse with the light ones of the lesser scaup male though.<ref name="DUb" /><ref name="carboneras1992" /><ref name="Madge" /><ref name="DUa" />

====Hybridization====
Particularly in the case of vagrant birds in Europe, the identification is complicated by similar-looking ''[[Aythya]]'' [[hybrid (biology)|hybrid]]s. Except for hybrids between the two scaup species, the most reliable mark is the black bill-tip of hybrids, whereas in the scaups only the very point ("nail") of the bill is black. This is even recognizable at considerable range, as the scaups' bills appear uniformly grey from a distance, whereas those of hybrids look two-colored. European hybrids typically involve the [[tufted duck]] (''A. fuligula''), yielding offspring that have a small nape crest unlike any European ''Aythya'' species. Female and immature hybrids typically lack the white bill base, except in those between lesser scaup and ring-necked duck, where the white extends to the eye region. But especially with juveniles, the bi-colored bill of hybrids is most diagnostic.
Hybrid combinations that are known from the wild and resemble the lesser scaup are:
* The occurrence of hybridization between lesser and greater scaup in the wild is disputed. Such hybrids could only be identified with certainty by [[DNA sequence]] comparison however. But while they may exist unnoticed, they cannot be frequent, as the species are largely [[sympatric]] and closely related, yet remain distinct, with no signs of significant [[introgression]].
* Hybrids between lesser scaup and ring-necked ducks are recognizable by very dark wings contrasting with a light grey underside more than in the lesser scaup but less than in the ring-necked duck.
* Hybrids between the lesser scaup and the [[redhead (duck)|redhead]] (''A. americana'') are recognizable by the lack of contrast between wings and belly and the dull brownish head.
* Hybrids between the tufted duck and the [[common pochard]] (''A. ferina'') are almost indistinguishable from lesser scaup, though neither parent species resembles ''A. affinis''.
In theory, each and every ''Aythya'' species is able to produce potentially [[fertility|fertile]] hybrids with any other, though due to their different ranges and behavioral cues given during courtship most of these hybrids are only known from birds kept in captivity without [[conspecific]] mates.<ref name = carboneras1992 /><ref name=Madge/>

== Taxonomy ==
Two [[Type (biology)|syntype specimens]] of ''Fuligula affinis'' Eyton ([https://doi.org/10.5962/bhl.title.51971 Monogr. Anat., 1838, p.157.]) are held in the vertebrate zoology collections of [[National Museums Liverpool]] at [[World Museum]], with accession numbers NML-VZ D826c (female adult) and NML-VZ D826b (male adult).<ref name=":0">{{Cite book|last=R. Wagstaffe|url=http://archive.org/details/type-specimens-of-birds-in-the-merseyside-county-museums-wagstaffe|title=Type Specimens of Birds in the Merseyside County Museums (formerly City of Liverpool Museums)|date=1978-12-01}}</ref> The specimens were collected in North America and came to the Liverpool national collection via [[Thomas Campbell Eyton]]'s collection and the [[13th Earl of Derby]]'s collection which was bequeathed to the people of Liverpool in 1851.<ref name=":0" />

== Distribution and migration ==
Their breeding habitats are inland [[lake]]s and [[Tundra|arctic]] [[marsh]] [[pond]]s from [[Alaska]] through western Canada to western [[Montana]]; few breed east of [[James Bay]] and the [[Great Lakes]]. Notable breeding concentrations, with more than half a million birds at the height of the season, can be found in Alaska, in the woodlands of the [[McKenzie River (Oregon)|McKenzie River]] valley and on the [[Old Crow Flats]]. These birds [[bird migration|migrate]] south (mostly via the [[Central Flyway|Central]] and [[Mississippi Flyway]]s) when the young are fledged and return early spring, usually arriving on the breeding ground in May. Lesser scaup typically travel in flocks of 25–50 birds and winter mainly on lakes, [[river]]s and sheltered coastal [[lagoon]]s and [[bay]]s between the US–Canada border and northern [[Colombia]], including [[Central America]], the [[West Indies]] and [[Bermuda]]. 

Wintering lesser scaup are typically found in [[freshwater]] or slightly [[brackish]] habitat and unlike [[greater scaup]] rarely are seen offshore when unfrozen freshwater habitat is available. They may even spend the winter on lakes in [[park]]s, as long as they are not harassed, and will occur even on smallish [[Caribbean]] islands such as [[Grand Cayman]]. Thousands winter each year on the [[Topolobampo]] lagoons in Mexico, and even in the southernmost major wintering location—[[Ciénaga Grande de Santa Marta]] in Colombia—hundreds of birds can be seen. In [[Central America]], flocks are present from July on, but only really numerous after September. They move north again in April and May. In the extreme southeast and southwest of the breeding range—the [[Rocky Mountains]] region of the northwestern United States and the southern Great Lakes—lesser scaup are present all-year; it is not clear whether the breeding birds are replaced by migrants from the far north in winter, or whether the local populations do not migrate, or whether both local and migrant birds are found there in winter.<ref name="DUb" /><ref name="carboneras1992" /><ref name="Madge" /><ref name="DUa" /><ref name="Olson" /><ref name="Herrera" />

They are rarely—but apparently increasingly often—seen as vagrants in western [[Europe]]. The first documented [[United Kingdom|British]] record was a first-winter male at [[Chasewater]], [[Staffordshire]] in 1987<ref name=Evans/> but by 2006, over 60 had been recorded, with an average of 2 per year. UK records are typically in the northern parts of the country. Vagrant lesser scaup have also been recorded on the [[Hawaiian Islands]],  Japan, possibly China, and—for the first time on 18 January 2000—in the [[Marianas]], as well as in [[Ecuador]], [[Suriname]], [[French Guiana]], [[Trinidad]] and [[Venezuela]] (in winter), and [[Greenland]] (in summer).<ref name=DUb/><ref name = carboneras1992 /><ref name=Madge/><ref name=Kerkhove/><ref name= Wiles/><ref name= BTO/>

==Ecology==
Lesser scaup forage mainly by sifting through the bottom mud, usually after diving and swimming underwater, occasionally by dabbling without diving. They mainly eat [[mollusk]]s such as [[mussel]]s and [[clam]]s, as well as seeds and other parts of aquatic plants like sedges and bulrushes ([[Cyperaceae]]), "[[pondweed]]s", [[widgeon-grass]] (''[[Ruppia cirrhosa]]''), wild celery (''[[Vallisneria americana]]'') or [[wild rice]] (''Zizania''). In winter, but less so in summer, other [[Aquatic animal|aquatic]] animals—[[crustacean]], [[insect]] and their [[larva]]e and small [[fish]]es—form an important part of their diet. It has been reported that both the lesser and the greater scaup have shifted their traditional migration routes to take advantage of the presence of the [[zebra mussel]] (''Dreissena polymorpha'') in [[Lake Erie]], which was accidentally introduced in the 1980s and has multiplied enormously. This may pose a risk to these birds because zebra mussels are efficient [[filter feeder]]s and so accumulate environmental contaminants rapidly.<ref name=DUb/><ref name = carboneras1992 /><ref name=DUa/><ref name=Custer/>

They nest in a sheltered location on the ground near water, usually among thick vegetation such as [[Cyperaceae|sedges and bulrushes]], sometimes in small loose groups and not rarely next to colonies of [[gull]]s or [[tern]]s; several females may deposit eggs in a single nest. The drakes court the hens in the winter quarters; pairs form shortly before and during the spring migration. When nesting starts, the males aggregate while they [[moult]] into [[eclipse plumage]], leaving the task of incubation and raising the young to the females alone.<ref name=Madge />

The nest is a shallow depression scraped in the ground and lined with plants and some [[down feather]]s. Breeding begins in May, but most birds nest only in June, later than usual for North American [[waterfowl]]. The [[clutch (eggs)|clutch]] numbers about 9–11 eggs on average; up to 26 eggs have been found in a single nest, but such high numbers are from more than one female. Incubation is by the female only and lasts around 3 weeks. The young [[fledge]] some 45–50 days after hatching and soon thereafter the birds migrate to winter quarters already. Lesser scaup become sexually mature in their first or second summer. The oldest known individual reached an age of over 18 years.<ref name = carboneras1992 /><ref name = AnAge />

Before the start of the population decline (see [[#Conservation status|below]]), about 57% of the lesser scaup nests failed each breeding season because the female was killed or the eggs were eaten or destroyed. The average brood size of nests where eggs hatched successfully was 8.33 hatchlings.<ref name = carboneras1992 />

==Conservation status==
Although the lesser scaup has the largest population of any species of diving duck in North America, their population has been steadily declining since the mid-1980s, and reached an all-time low in the early 21st century. During [[breeding bird survey]]s, lesser and [[greater scaup]] are counted together due to the impossibility of identifying the species unequivocally when large numbers of birds are involved. Lesser scaup are thought to comprise slightly less than nine-tenths of the scaup population of North America. In the 1970s, the lesser scaup population was estimated at 6.9 million birds on average; in the 1990s it had declined to about half that number, and by the late 2000s it is estimated at 3 million individuals or less. Due to the wide breeding range and the fact that the rate of decline, though remarkable, is still not threatening in respect to the enormous overall numbers, the lesser scaup is classified as a Species of [[Least Concern]] by the [[IUCN]]. An increase of the decline is liable to result in an uplisting to [[Near Threatened]] or even [[Vulnerable species|Vulnerable]] status.<ref name="iucn status 12 November 2021" /><ref name=DUb/><ref name = carboneras1992 /><ref name=DUa/>

The causes for this stark—though not threatening yet—decline remain unknown. There are indications that the breeding success is decreasing, but why this is so remains puzzling. On one hand, [[pollution]] and [[habitat destruction]], especially in the wintering regions, has certainly increased since the early-mid 20th century. On the other hand, the narrow time frame in which lesser scaup breed and raise their young may be tied to some specific ecological conditions—such as abundance of key food, without the ducks being able to adapt. In this regard, it is alternatively or additionally possible that greater scaup, which may be increasing in numbers, is putting the lesser scaup under increasingly severe competition.{{citation needed|date=January 2016}}

However, it seems that greater scaup eats larger food items on average,<ref name=Custer/> and the species are [[sympatric]] in part of their range and presumably have been for millennia without any problems due to competition. The experience of the past as well as the reproduction rate—even if this is declining—suggests that [[hunting]] has no major impact on lesser scaup populations at present either. Also, the breeding habitat is mainly in regions little-used by humans; habitat destruction on the breeding grounds is also not considered to be problematic.&nbsp;<ref name = carboneras1992 />

==References==
{{Reflist|refs=
<ref name=AnAge>[http://genomics.senescence.info/species/entry.php?species=Aythya_affinis ''Aythya affinis'' life history data]. genomics.senescence.info</ref>

<ref name=BTO>[http://blx1.bto.org/birdfacts/results/bob2050.htm Lesser Scaup ''Aythya affinis'' (Eyton, 1838)]. [[British Trust for Ornithology]]</ref>

<ref name = carboneras1992 >Carboneras, Carles (1992): 121. Lesser Scaup. ''In:'' del Hoyo, Josep; Elliott, Andrew & Sargatal, Jordi (eds.): ''[[Handbook of Birds of the World]]'' (Vol. 1: Ostrich to Ducks): 618–619, plate 48. Lynx Edicions, Barcelona. {{ISBN|84-87334-10-5}}</ref>

<ref name= Cornell>[http://www.allaboutbirds.org/guide/Lesser_Scaup/lifehistory Lesser Scaup]. The Cornell Lab of Ornithology. allaboutbirds.org</ref>

<ref name=Custer>{{cite journal|author1=Custer, Christine M.  |author2=Custer, Thomas W. |year=1996|title= Food habits of diving ducks in the Great Lakes after the zebra mussel invasion|journal=Journal of Field Ornithology|volume=67|issue=1|pages= 86–99|bibcode=1996JFOrn..67...86C |url=http://sora.unm.edu/sites/default/files/journals/jfo/v067n01/p0086-p0099.pdf }}</ref>

<ref name =DUa>[http://www.ducks.org/news/1093/DuckoftheMonthLesser.html Duck of the Month &ndash; Lesser Scaup] {{Webarchive|url=https://web.archive.org/web/20190209124248/http://www.ducks.org/news/1093/DuckoftheMonthLesser.html |date=2019-02-09 }}. Ducks Unlimited</ref>

<ref name=DUb>[http://www.ducks.org/hunting/waterfowlgallery/11/index.html Lesser scaup] {{webarchive|url=https://web.archive.org/web/20080102024938/http://www.ducks.org/hunting/waterfowlgallery/11/index.html |date=2008-01-02 }}. Ducks Unlimited</ref>

<ref name= Evans >{{cite journal|author= Evans, Graham |year=1987|title= Britain's first Lesser Scaup|journal=[[Twitching (magazine)|Twitching]]|volume=1|issue=3|pages= 65–66|url=http://www.westmidlandbirdclub.com/biblio/twitching/lesserscaup.htm|url-status= unfit |archive-url=https://web.archive.org/web/20120805185947/http://www.westmidlandbirdclub.com/bibliography/twitching/lesserscaup.htm|archive-date=5 August 2012}}</ref>

<ref name= Herrera >{{cite journal|author1=Herrera, Néstor |author2=Rivera, Roberto |author3=Ibarra Portillo |author4= Ricardo |author5=Rodríguez, Wilfredo |year=2006|title= Nuevos registros para la avifauna de El Salvador|trans-title=New records for the avifauna of El Salvador|journal=Boletín de la Sociedad Antioqueña de Ornitología|volume=16|issue=2|pages= 1–19|language=Spanish, English|url=http://www.sao.org.co/publicaciones/boletinsao/01-Herrera.etal.RecordsSalvador.pdf}}</ref>

<ref name=Kerkhove>{{cite journal |journal=Cotinga |volume=42 |year=2020 |pages=24–26 |first1=Thomas R. H. |last1=Kerkhove |first2=Kévin |last2=Pineau |first3=Carl |last3=Beel |first4=Olivier |last4=Claessens |first5=Johan |last5=Ingels |title=Vagrant Ring-necked Duck ''Aythya collaris'' and Lesser Scaup ''A. affinis'' in French Guiana and Suriname}}</ref>

<ref name= Livezey >{{cite journal|author= Livezey, Brad C. |year=1998|title= A phylogenetic analysis of modern pochards (Anatidae: Aythyini)|journal=[[Auk (journal)|Auk]]|volume=113|issue=1|pages= 74–93|url=http://sora.unm.edu/sites/default/files/journals/auk/v113n01/p0074-p0093.pdf|doi= 10.2307/4088937|jstor=4088937}}</ref>

<ref name =Madge>Madge, Steve & Burn, Hilary (1987): ''Wildfowl: an identification guide to the ducks, geese and swans of the world''. [[Helm Identification Guides|Christopher Helm]], London. {{ISBN|0-7470-2201-1}}</ref>

<ref name= Olson>{{cite journal |author1=Olson, Storrs L. |author2=James, Helen F. |author3=Meister, Charles A. |year=1981 |title=Winter field notes and specimen weights of Cayman Island Birds |journal=[[Bulletin of the British Ornithologists' Club|Bull. B.O.C.]] |volume=101 |issue=3 |pages=339–346 |url=http://si-pddr.si.edu/dspace/bitstream/10088/6535/1/VZ_119_Cayman_bird_weights.pdf |archive-date=2012-02-27 |access-date=2009-10-30 |archive-url=https://web.archive.org/web/20120227001814/http://si-pddr.si.edu/dspace/bitstream/10088/6535/1/VZ_119_Cayman_bird_weights.pdf }}</ref>

<ref name=Wiles>{{cite journal|author1=Wiles, Gary J. |author2=Johnson, Nathan C. |author3=de Cruz, Justine B. |author4=Dutson, Guy |author5=Camacho, Vicente A. |author6=Kepler, Angela Kay |author7=Vice, Daniel S. |author8=Garrett, Kimball L. |author9=Kessler, Curt C. |author10=Pratt, H. Douglas |year=2004 |title=New and Noteworthy Bird Records for Micronesia, 1986–2003 |journal=Micronesica |volume=37 |issue=1 |pages=69–96 |url=http://www.uog.edu/up/micronesica/Vol37abstracts.asp |archive-url=https://web.archive.org/web/20090505164356/http://www.uog.edu/up/micronesica/Vol37abstracts.asp |archive-date=2009-05-05 }}</ref>
}}

==Further reading==
* Farrand, John Jr. & [[National Audubon Society]] (1983): ''The Audubon Society master guide to birding''. Alfred A. Knopf, New York. {{ISBN|0-517-03288-0}}
* Svensson, Lars; Zetterström, Dan; Mullarney, Killian & Grant, P. J. (1999): ''Collins bird guide''. Harper & Collins, London. {{ISBN|0-00-219728-6}}

==External links==
{{Commons category|Aythya affinis|Lesser Scaup}}
{{Wikispecies|Aythya affinis}}
* {{Avibase|name=Aythya affinis}}
*[https://www.mbr-pwrc.usgs.gov/id/framlst/i1490id.html Lesser Scaup - ''Aythya affinis'']{{Dead link|date=August 2025 |bot=InternetArchiveBot |fix-attempted=yes }} - USGS Patuxent Bird Identification InfoCenter
*[http://www.nature.org/newsfeatures/specialfeatures/animals/birds/lesser-scaup.xml The Nature Conservancy's Species profile for the Lesser Scaup] {{Webarchive|url=https://web.archive.org/web/20131203020729/http://www.nature.org/newsfeatures/specialfeatures/animals/birds/lesser-scaup.xml |date=2013-12-03 }}
* {{InternetBirdCollection|lesser-scaup-aythya-affinis|Lesser Scaup}}
* {{VIREO|lesser+scaup|Lesser Scaup}}
* {{IUCN_Map|22680402/139381357|Aythya affinis}}

{{North American Game}}

{{Taxonbar|from=Q833243}}
{{Authority control}}

[[Category:Aythya|lesser scaup]]
[[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 of the Dominican Republic]]
[[Category:Birds of Haiti]]
[[Category:Birds described in 1838|lesser scaup]]
[[Category:Taxa named by Thomas Campbell Eyton|lesser scaup]]