Lesser scaup
   HOME

TheInfoList



OR:

The lesser scaup (''Aythya affinis'') is a small
North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...
n
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 ...
that migrates south as far as
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
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. It is apparently a very close relative of the
Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical reg ...
greater scaup The greater scaup (''Aythya marila''), just scaup in Europe or, colloquially, "bluebill" in North America, is a mid-sized diving duck, larger than the closely related lesser scaup. It spends the summer months breeding in Alaska, northern Canad ...
or "bluebill" (''A. marila''), with which it forms a superspecies. The scientific name is derived from
Ancient Greek Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
''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 phil ...
, and
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, ''affinis'' "related to", from its resemblance to the greater scaup.


Description

Adults are long, on average. The species can weigh ; males weigh on average and females weigh noticeably less, at on average. Wing lengths (not
wingspan The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingspan of ...
s) are about in males and in females; the tarsus is about long, and the bill . The wingspan is . The adult males (drakes) in definitive basic (breeding) plumage have a black, iridescent head and a small tuft at the hindcrown, a black breast, a whitish-grey back and wings with darker
vermiculation Vermiculation is a surface pattern of dense but irregular lines, so called from the Latin ''vermiculus'' meaning "little worm" because the shapes resemble worms, worm-casts, or worm tracks in mud or wet sand. The word may be used in a number of ...
s and black outer and greyish-brown inner primary
remiges Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...
. The underparts are white with some
olive The olive, botanical name ''Olea europaea'', meaning 'European olive' in Latin, is a species of small tree or shrub in the family Oleaceae, found traditionally in the Mediterranean Basin. When in shrub form, it is known as ''Olea europaea'' ...
vermiculations on the flanks, and the
rectrices Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...
and tail coverts are black. Adult females (hens) have a white band at the base of the bill, often a lighter ear region, and are otherwise dark brown all over, shading to white on the mid-belly. Drakes in
eclipse plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...
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 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 ...
, while that of females is orange to yellow varying with age and that of immatures is brown.
Downy Downy, also known as Lenor in Europe, Russia and Japan, is a brand of fabric softener produced by Procter & Gamble that was introduced in 1960. Lenor is a brand name of fabric softener and dryer sheets, also produced by P&G, sold in Europe, Rus ...
hatchlings look much like those of related species, with dark brown upperparts and pale
buff Buff or BUFF may refer to: People * Buff (surname), a list of people * Buff (nickname), a list of people * Johnny Buff, ring name of American world champion boxer John Lisky (1888–1955) * Buff Bagwell, a ring name of American professional ...
underparts, chin,
supercilium The supercilium is a plumage feature found on the heads of some bird species. It is a stripe which runs from the base of the bird's beak above its eye, finishing somewhere towards the rear of the bird's head.Dunn and Alderfer (2006), p. 10 Also ...
and back spots. These birds are not very vocal, at least compared to
dabbling duck The Anatinae are a subfamily of the family Anatidae ( swans, geese and ducks). Its surviving members are the dabbling ducks, which feed mainly at the surface rather than by diving. The other members of the Anatinae are the extinct moa-nalo, a yo ...
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 The greater scaup (''Aythya marila''), just scaup in Europe or, colloquially, "bluebill" in North America, is a mid-sized diving duck, larger than the closely related lesser scaup. It spends the summer months breeding in Alaska, northern Canad ...
—particularly during flight—but their call is weaker, a guttural ''brrtt, brrtt''.


Identification

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. Lesser scaup are often hard to distinguish from the
greater scaup The greater scaup (''Aythya marila''), just scaup in Europe or, colloquially, "bluebill" in North America, is a mid-sized diving duck, larger than the closely related lesser scaup. It spends the summer months breeding in Alaska, northern Canad ...
when direct comparison is not possible, but in North America a large 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. In flight, the most tell-tale sign is the white secondary
remiges Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...
, whereas in the greater scaup the white extends on the primary remiges also, i.e. far towards the wingtip. 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 The ring-necked duck (''Aythya collaris'') is a diving duck from North America commonly found in freshwater ponds and lakes. The scientific name is derived from Greek , an unidentified seabird mentioned by authors including Hesychius and Arist ...
(''A. collaris''); the black back and wings of that species are hard to confuse with the light ones of the lesser scaup male though.


Hybridization

Particularly in the case of vagrant birds in Europe, the identification is complicated by similar-looking ''
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 ...
''
hybrid Hybrid may refer to: Science * Hybrid (biology), an offspring resulting from cross-breeding ** Hybrid grape, grape varieties produced by cross-breeding two ''Vitis'' species ** Hybridity, the property of a hybrid plant which is a union of two dif ...
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 The tufted duck or tufted pochard (''Aythya fuligula'') is a small diving duck with a population of close to one million birds, found in northern Eurasia. The scientific name is derived from Ancient Greek '' aithuia'', an unidentified seabird ment ...
(''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 DNA sequencing is the process of determining the nucleic acid sequence – the order of nucleotides in DNA. It includes any method or technology that is used to determine the order of the four bases: adenine, guanine, cytosine, and thymine. Th ...
comparison however. But while they may exist unnoticed, they cannot be frequent, as the species are largely
sympatric In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...
and closely related, yet remain distinct, with no signs of significant
introgression Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Intr ...
. * 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 Red hair (also known as orange hair and ginger hair) is a hair color found in one to two percent of the human population, appearing with greater frequency (two to six percent) among people of Northern or Northwestern European ancestry and ...
(''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 The common pochard (; ''Aythya ferina'') is a medium-sized diving duck. The scientific name is derived from Greek '' aithuia'', an unidentified seabird mentioned by authors including Hesychius and Aristotle, and Latin ''ferina'', "wild game", ...
(''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
fertile Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertilit ...
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 Biological specificity is the tendency of a characteristic such as a behavior or a biochemical variation to occur in a particular species. Biochemist Linus Pauling stated that "Biological specificity is the set of characteristics of living organ ...
mates.


Taxonomy

Two syntype specimens of ''Fuligula affinis'' Eyton
Monogr. Anat., 1838, p.157.
are held in the vertebrate zoology collections of
National Museums Liverpool National Museums Liverpool, formerly National Museums and Galleries on Merseyside, comprises several museums and art galleries in and around Liverpool, England. All the museums and galleries in the group have free admission. The museum is a non ...
at
World Museum World Museum is a large museum in Liverpool, England which has extensive collections covering archaeology, ethnology and the natural and physical sciences. Special attractions include the Natural History Centre and a planetarium. Entry to the ...
, with accession numbers NML-VZ D826c (female adult) and NML-VZ D826b (male adult). The specimens were collected in North America and came to the Liverpool national collection via
Thomas Campbell Eyton Thomas Campbell Eyton JP, DL (10 September 1809 – 25 October 1880) was an English naturalist whose fields were cattle, fishes and birds. He was a friend and correspondent of Charles Darwin though he opposed his theories. Eyton was born at ...
’s collection and the 13th Earl of Derby’s collection which was bequeathed to the people of Liverpool in 1851.


Distribution and migration

Their breeding habitat is inland
lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...
s and
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 at ...
pond A pond is an area filled with water, either natural or artificial, that is smaller than a lake. Defining them to be less than in area, less than deep, and with less than 30% emergent vegetation helps in distinguishing their ecology from th ...
s in
tundra In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless moun ...
from
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., ...
through western Canada to western
Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...
; few breed east of
James Bay James Bay (french: Baie James; cr, ᐐᓂᐯᒄ, Wînipekw, dirty water) is a large body of water located on the southern end of Hudson Bay in Canada. Both bodies of water extend from the Arctic Ocean, of which James Bay is the southernmost par ...
and the
Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five 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 valley and on the
Old Crow Flats Old Crow Flats (''Van Tat'' in the Gwichʼin language) is a wetland complex in northern Yukon, Canada along the Old Crow River. It is north of the Arctic Circle and south of the Beaufort Sea, and is nearly surrounded by mountains. Site The site ...
. These birds migrate south (mostly via the
Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...
and
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 t ...
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 A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
s and sheltered coastal
lagoon A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') a ...
s and bays between the US–Canada border and northern
Colombia Colombia (, ; ), officially the Republic of Colombia, is a country in South America with insular regions in North America—near Nicaragua's Caribbean coast—as well as in the Pacific Ocean. The Colombian mainland is bordered by the Car ...
, including
Central America Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
, the
West Indies The West Indies is a subregion of North America, surrounded by the North Atlantic Ocean and the Caribbean Sea that includes 13 independent island countries and 18 dependencies and other territories in three major archipelagos: the Greater A ...
and
Bermuda ) , anthem = "God Save the King" , song_type = National song , song = " Hail to Bermuda" , image_map = , map_caption = , image_map2 = , mapsize2 = , map_caption2 = , subdivision_type = Sovereign state , subdivision_name = , e ...
. Wintering lesser scaup are typically found in
freshwater Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include ...
or slightly
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 estuari ...
habitat and unlike
greater scaup The greater scaup (''Aythya marila''), just scaup in Europe or, colloquially, "bluebill" in North America, is a mid-sized diving duck, larger than the closely related lesser scaup. It spends the summer months breeding in Alaska, northern Canad ...
rarely are seen offshore when unfrozen freshwater habitat is available. They may even spend the winter on lakes in
park A park is an area of natural, semi-natural or planted space set aside for human enjoyment and recreation or for the protection of wildlife or natural habitats. Urban parks are urban green space, green spaces set aside for recreation inside t ...
s, as long as they are not harassed, and will occur even on smallish
Caribbean The Caribbean (, ) ( es, El Caribe; french: la Caraïbe; ht, Karayib; nl, De Caraïben) is a region of the Americas that consists of the Caribbean Sea, its islands (some surrounded by the Caribbean Sea and some bordering both the Caribbean Se ...
islands such as
Grand Cayman Grand Cayman is the largest of the three Cayman Islands and the location of the territory's capital, George Town. In relation to the other two Cayman Islands, it is approximately 75 miles (121 km) southwest of Little Cayman and 90 miles ( ...
. Thousands winter each year on the
Topolobampo Topolobampo () is a port on the Gulf of California in northwestern Sinaloa, Mexico. It is the fourth-largest town in the municipality of Ahome (after Los Mochis, Ahome, and Higuera de Zaragoza), reporting a 2010 census population of 6,361 inhabit ...
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 Central America ( es, América Central or ) is a subregion of the Americas. Its boundaries are defined as bordering the United States to the north, Colombia to the south, the Caribbean Sea to the east, and the Pacific Ocean to the west. ...
, 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 The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...
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. They are rarely—but apparently increasingly often—seen as vagrants in western
Europe Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
. The first documented
British British may refer to: Peoples, culture, and language * British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies. ** Britishness, the British identity and common culture * British English, ...
record was a first-winter male at
Chasewater Chasewater is a reservoir located in the parish of Burntwood and the district of Lichfield in Staffordshire, England. Originally known as Norton Pool and Cannock Chase Reservoir, it was created as a canal feeder reservoir in 1797. The reservoi ...
,
Staffordshire Staffordshire (; postal abbreviation Staffs.) is a landlocked county in the West Midlands region of England. It borders Cheshire to the northwest, Derbyshire and Leicestershire to the east, Warwickshire to the southeast, the West Midlands Cou ...
in 1987 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 The Hawaiian Islands ( haw, Nā Mokupuni o Hawai‘i) are an archipelago of eight major islands, several atolls, and numerous smaller islets in the North Pacific Ocean, extending some from the island of Hawaii in the south to northernmost Kur ...
Japan, possibly China, and—for the first time on 18 January 2000—in the
Marianas The Mariana Islands (; also the Marianas; in Chamorro: ''Manislan Mariånas'') are a crescent-shaped archipelago comprising the summits of fifteen longitudinally oriented, mostly dormant volcanic mountains in the northwestern Pacific Ocean, betw ...
, as well as in
Ecuador Ecuador ( ; ; Quechua: ''Ikwayur''; Shuar: ''Ecuador'' or ''Ekuatur''), officially the Republic of Ecuador ( es, República del Ecuador, which literally translates as "Republic of the Equator"; Quechua: ''Ikwadur Ripuwlika''; Shuar: ''Eku ...
,
Suriname Suriname (; srn, Sranankondre or ), officially the Republic of Suriname ( nl, Republiek Suriname , srn, Ripolik fu Sranan), is a country on the northeastern Atlantic coast of South America. It is bordered by the Atlantic Ocean to the north ...
,
French Guiana French Guiana ( or ; french: link=no, Guyane ; gcr, label=French Guianese Creole, Lagwiyann ) is an overseas departments and regions of France, overseas department/region and single territorial collectivity of France on the northern Atlantic ...
,
Trinidad Trinidad is the larger and more populous of the two major islands of Trinidad and Tobago. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is often referred to as the southernmos ...
and
Venezuela Venezuela (; ), officially the Bolivarian Republic of Venezuela ( es, link=no, República Bolivariana de Venezuela), is a country on the northern coast of South America, consisting of a continental landmass and many islands and islets in th ...
(in winter), and
Greenland Greenland ( kl, Kalaallit Nunaat, ; da, Grønland, ) is an island country in North America that is part of the Kingdom of Denmark. It is located between the Arctic and Atlantic oceans, east of the Canadian Arctic Archipelago. Greenland is t ...
(in summer).


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 Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000  extant species of molluscs are recognized. The number of fossil species is e ...
s such as
mussel Mussel () is the common name used for members of several families of bivalve molluscs, from saltwater and Freshwater bivalve, freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other ...
s and
clam Clam is a common name for several kinds of bivalve molluscs. The word is often applied only to those that are edible and live as infauna, spending most of their lives halfway buried in the sand of the seafloor or riverbeds. Clams have two she ...
s, as well as seeds and other parts of aquatic plants like sedges and bulrushes (
Cyperaceae The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' w ...
), "
pondweed Pondweed refers to many species and genera of aquatic plants and green algae: *''Potamogeton'', a diverse and worldwide genus *''Elodea'', found in North America *''Aponogeton'', in Africa, Asia and Australasia *''Groenlandia ''Groenlandia'' is ...
s", widgeon-grass (''
Ruppia cirrhosa ''Ruppia cirrhosa'' is a species of aquatic plant Aquatic plants are plants that have adapted to living in aquatic environments (saltwater or freshwater). They are also referred to as hydrophytes or macrophytes to distinguish them from algae ...
''), 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 ...
'') or
wild rice Wild rice, also called manoomin, Canada rice, Indian rice, or water oats, is any of four species of grasses that form the genus ''Zizania'', and the grain that can be harvested from them. The grain was historically gathered and eaten in both ...
(''Zizania''). In winter, but less so in summer, other aquatic animals—
crustacean Crustaceans (Crustacea, ) form a large, diverse arthropod taxon which includes such animals as decapods, seed shrimp, branchiopods, fish lice, krill, remipedes, isopods, barnacles, copepods, amphipods and mantis shrimp. The crustacean group ...
,
insect Insects (from Latin ') are pancrustacean hexapod invertebrates of the class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body ( head, thorax and abdomen), three pairs ...
and their
larva A larva (; plural larvae ) is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle. The ...
e and small
fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...
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 The zebra mussel (''Dreissena polymorpha'') is a small freshwater mussel. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally introduced to numerous other areas and has become an invasive species in ma ...
(''Dreissena polymorpha'') in
Lake Erie Lake Erie ( "eerie") is the fourth largest lake by surface area of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has t ...
, 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 Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
s and so accumulate environmental contaminants rapidly. They nest in a sheltered location on the ground near water, usually among thick vegetation such as sedges and bulrushes, sometimes in small loose groups and not rarely next to colonies of
gull Gulls, or colloquially seagulls, are seabirds of the family Laridae in the suborder Lari. They are most closely related to the terns and skimmers and only distantly related to auks, and even more distantly to waders. Until the 21st century, m ...
s or
tern Terns are seabirds in the family Laridae that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated as a subgroup of the family Laridae which includes gulls and skimmers and consists of e ...
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 In biology, moulting (British English), or molting (American English), also known as sloughing, shedding, or in many invertebrates, ecdysis, is the manner in which an animal routinely casts off a part of its body (often, but not always, an outer ...
into
eclipse plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...
, leaving the task of incubation and raising the young to the females alone. The nest is a shallow depression scraped in the ground and lined with plants and some
down feather The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator an ...
s. Breeding begins in May, but most birds nest only in June, later than usual for North American
waterfowl Anseriformes is an order of birds also known as waterfowl that comprises about 180 living species of birds in three families: Anhimidae (three species of screamers), Anseranatidae (the magpie goose), and Anatidae, the largest family, which in ...
. The
clutch A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...
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 Fledging is the stage in a flying animal's life between hatching or birth and becoming capable of flight. This term is most frequently applied to birds, but is also used for bats. For altricial birds, those that spend more time in vulnerable c ...
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. Before the start of the population decline (see 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.


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 surveys, lesser and
greater scaup The greater scaup (''Aythya marila''), just scaup in Europe or, colloquially, "bluebill" in North America, is a mid-sized diving duck, larger than the closely related lesser scaup. It spends the summer months breeding in Alaska, northern Canad ...
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 A least-concern species is a species that has been categorized by the International Union for Conservation of Nature (IUCN) as evaluated as not being a focus of species conservation because the specific species is still plentiful in the wild. T ...
by the
IUCN The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
. An increase of the decline is liable to result in an uplisting to
Near Threatened A near-threatened species is a species which has been categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature as that may be vulnerable to endangerment in the near future, but it does not currently qualify fo ...
or even Vulnerable status. 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 Pollution is the introduction of contaminants into the natural environment that cause adverse change. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the ...
and
habitat destruction Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
, 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 items—which shifted winterwards due to
global warming In common usage, climate change describes global warming—the ongoing increase in global average temperature—and its effects on Earth's climate system. Climate change in a broader sense also includes previous long-term changes to E ...
, 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. However, it seems that greater scaup eats larger food items on average, and the species are
sympatric In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...
in part of their range and presumably have been for millennium 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 Hunting is the human activity, human practice of seeking, pursuing, capturing, or killing wildlife or feral animals. The most common reasons for humans to hunt are to harvest food (i.e. meat) and useful animal products (fur/hide (skin), hide, ...
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. 


References


Further reading

* Farrand, John Jr. &
National Audubon Society The National Audubon Society (Audubon; ) is an American non-profit environmental organization dedicated to conservation of birds and their habitats. Located in the United States and incorporated in 1905, Audubon is one of the oldest of such organ ...
(1983): ''The Audubon Society master guide to birding''. Alfred A. Knopf, New York. * Svensson, Lars; Zetterström, Dan; Mullarney, Killian & Grant, P. J. (1999): ''Collins bird guide''. Harper & Collins, London.


External links

*
Lesser Scaup - ''Aythya affinis''
- USGS Patuxent Bird Identification InfoCenter
The Nature Conservancy's Species profile for the Lesser Scaup
* * * {{Taxonbar, from=Q833243
lesser scaup The lesser scaup (''Aythya affinis'') is a small North American 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 ...
Native birds of Alaska Native birds of Western Canada Native birds of the Canadian Prairies Native birds of the Northwestern United States Birds of Hispaniola Birds of the Dominican Republic Birds of Haiti
lesser scaup The lesser scaup (''Aythya affinis'') is a small North American 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 ...
lesser scaup The lesser scaup (''Aythya affinis'') is a small North American 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 ...