The lesser scaup (''Aythya affinis'') is a small
North America
North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...
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 ...
that migrates south as far as
Central America
Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
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 and tufted duck. It spends the summer months breeding in Iceland ...
or "bluebill" (''A. marila''), with which it forms a superspecies
In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
.[ The scientific name is derived from ]Ancient Greek
Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...
and Latin
Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...
, with ''aithuia'' being an Ancient Greek term for an unidentified seabird
Seabirds (also known as marine birds) are birds that are adaptation, adapted to life within the marine ecosystem, marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent ...
, used by Hesychius and Aristotle
Aristotle (; 384–322 BC) was an Ancient Greek philosophy, Ancient Greek philosopher and polymath. His writings cover a broad range of subjects spanning the natural sciences, philosophy, linguistics, economics, politics, psychology, a ...
, among other authors, and ''affinis'', Latin for "related to", from the lesser scaup's resemblance to the greater scaup.
Description
Adults are long, on average. The species can weigh ; males weigh on average while 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 opposite wingtip. For example, the Boeing 777–200 has a wingspan of , and a wandering albatross (''Diomedea exulans'') caught in 1965 had a wingsp ...
s) are about in males and in females. The tarsus is about long, and the bill is .[ 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, wings with darker ]vermiculation
Vermiculation is a surface pattern of dense but irregular lines, so called from the Latin 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 contexts for ...
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 ta ...
. The underparts are white with some olive
The olive, botanical name ''Olea europaea'' ("European olive"), is a species of Subtropics, subtropical evergreen tree in the Family (biology), family Oleaceae. Originating in Anatolia, Asia Minor, it is abundant throughout the Mediterranean ...
vermiculations on the flanks, and the rectrices
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the Bird wing, wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those ...
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
Plumage () 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, there can b ...
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, 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, Taiwan and Japan, is an American brand of fabric softener produced by Procter & Gamble that was introduced in 1960.
Brand history
Lenor is a brand name of fabric softener and dryer sheets, also produced by ...
hatchlings look much like those of related species, with dark brown upperparts and pale buff 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 k ...
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 y ...
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 and tufted duck. It spends the summer months breeding in Iceland ...
—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 and tufted duck. It spends the summer months breeding in Iceland ...
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 ta ...
, 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, with twelve species currently accepted. The genus was described in 1822 by the German zoologist Friedrich Boie, with the type species being greater scaup. The name ''Aythya'' comes from the Ancient Greek ...
'' 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 diff ...
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 nearly one million birds, found in northern Eurasia. They are partially migratory. The scientific name is derived from Ancient Greek , an unide ...
(''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
A nucleic acid sequence is a succession of bases within the nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. This succession is denoted by a series of a set of five different letters that indicate the order of the nu ...
comparison however. But while they may exist unnoticed, they cannot be frequent, as the species are largely sympatric
In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...
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. Introg ...
.
* 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 ginger hair, is a human hair color found in 2–6% of people of Northern or Northwestern European ancestry and lesser frequency in other populations. It is most common in individuals homozygous for a recessive alle ...
(''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''), known simply as pochard in the United Kingdom, is a medium-sized diving duck in the family Anatidae. It is widespread across the Palearctic. It breeds primarily in the steppe regions of Scandinavia and Si ...
(''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 in colloquial terms refers the ability to have offspring. In demographic contexts, fertility refers to the actual production of offspring, rather than the physical capability to reproduce, which is termed fecundity. The fertility rate is ...
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 organism ...
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 in Merseyside, England. All the museums and galleries in the group have free admission. The mu ...
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
Edward Smith-Stanley, 13th Earl of Derby (21 April 1775 – 30 June 1851), styled Lord Stanley from 1776 to 1832, and Baron Stanley of Bickerstaffe from 1832–4, was an English politician, peer, landowner, builder, farmer, art collector and na ...
’s collection which was bequeathed to the people of Liverpool in 1851.
Distribution and migration
Their breeding habitats are inland lake
A lake is often a naturally occurring, relatively large and fixed body of water on or near the Earth's surface. It is localized in a basin or interconnected basins surrounded by dry land. Lakes lie completely on land and are separate from ...
s and arctic
The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...
marsh
In ecology, a marsh is a wetland that is dominated by herbaceous plants rather than by woody plants.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p More in genera ...
pond
A pond is a small, still, land-based body of water formed by pooling inside a depression (geology), depression, either naturally or artificiality, artificially. A pond is smaller than a lake and there are no official criteria distinguishing ...
s from Alaska
Alaska ( ) is a non-contiguous U.S. state on the northwest extremity of North America. Part of the Western United States region, it is one of the two non-contiguous U.S. states, alongside Hawaii. Alaska is also considered to be the north ...
through western Canada to western Montana
Montana ( ) is a landlocked U.S. state, state in the Mountain states, Mountain West subregion of the Western United States. It is bordered by Idaho to the west, North Dakota to the east, South Dakota to the southeast, Wyoming to the south, an ...
; few breed east of James Bay
James Bay (, ; ) is a large body of water located on the southern end of Hudson Bay in Canada. It borders the provinces of Quebec and Ontario, and is politically part of Nunavut. Its largest island is Akimiski Island.
Numerous waterways of the ...
and the Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, H ...
. 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
Migration, migratory, or migrate may refer to: Human migration
* Human migration, physical movement by humans from one region to another
** International migration, when peoples cross state boundaries and stay in the host state for some minimum le ...
south (mostly via the Central 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 stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...
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'') an ...
s and bay
A bay is a recessed, coastal body of water that directly connects to a larger main body of water, such as an ocean, a lake, or another bay. A large bay is usually called a ''gulf'', ''sea'', ''sound'', or ''bight''. A ''cove'' is a small, ci ...
s between the US–Canada border and northern Colombia
Colombia, officially the Republic of Colombia, is a country primarily located in South America with Insular region of Colombia, insular regions in North America. The Colombian mainland is bordered by the Caribbean Sea to the north, Venezuel ...
, including Central America
Central America is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
, the West Indies
The West Indies is an island subregion of the Americas, surrounded by the Atlantic Ocean, North Atlantic Ocean and the Caribbean Sea, which comprises 13 independent island country, island countries and 19 dependent territory, dependencies in thr ...
and Bermuda
Bermuda is a British Overseas Territories, British Overseas Territory in the Atlantic Ocean, North Atlantic Ocean. The closest land outside the territory is in the American state of North Carolina, about to the west-northwest.
Bermuda is an ...
.
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. The term excludes seawater and brackish water, but it does include non-salty mi ...
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 and tufted duck. It spends the summer months breeding in Iceland ...
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 ( , ; ; ; ) is a region in the middle of the Americas centered around the Caribbean Sea in the Atlantic Ocean, North Atlantic Ocean, mostly overlapping with the West Indies. Bordered by North America to the north, Central America ...
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, Cayman Islands, George Town. In relation to the other two Cayman Islands, it is approximately 75 miles (121 km) southwest of L ...
. 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 inhab ...
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 is a subregion of North America. Its political boundaries are defined as bordering Mexico to the north, Colombia to the southeast, the Caribbean to the east, and the Pacific Ocean to the southwest. Central America is usually ...
, 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 great-circle distance, straight-line distance from the northernmost part of Western Can ...
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 continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
. 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.
* British national identity, the characteristics of British people and culture ...
record was a first-winter male at Chasewater, Staffordshire
Staffordshire (; postal abbreviation ''Staffs''.) is a Ceremonial counties of England, ceremonial county in the West Midlands (region), West Midlands of England. It borders Cheshire to the north-west, Derbyshire and Leicestershire to the east, ...
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 () are an archipelago of eight major volcanic islands, several atolls, and numerous smaller islets in the Pacific Ocean, North Pacific Ocean, extending some from the Hawaii (island), island of Hawaii in the south to nort ...
Japan, possibly China, and—for the first time on 18 January 2000—in the Marianas
The Mariana Islands ( ; ), also simply the Marianas, are a crescent-shaped archipelago comprising the summits of fifteen longitudinally oriented, mostly Volcano#Dormant and reactivated, dormant volcanic mountains in the northwestern Pacific Ocean ...
, as well as in Ecuador
Ecuador, officially the Republic of Ecuador, is a country in northwestern South America, bordered by Colombia on the north, Peru on the east and south, and the Pacific Ocean on the west. It also includes the Galápagos Province which contain ...
, Suriname
Suriname, officially the Republic of Suriname, is a country in northern South America, also considered as part of the Caribbean and the West Indies. It is a developing country with a Human Development Index, high level of human development; i ...
, French Guiana
French Guiana, or Guyane in French, is an Overseas departments and regions of France, overseas department and region of France located on the northern coast of South America in the Guianas and the West Indies. Bordered by Suriname to the west ...
, Trinidad
Trinidad is the larger, more populous island of the Republic of Trinidad and Tobago, the country. The island lies off the northeastern coast of Venezuela and sits on the continental shelf of South America. It is the southernmost island in ...
and Venezuela
Venezuela, officially the Bolivarian Republic of Venezuela, is a country on the northern coast of South America, consisting of a continental landmass and many Federal Dependencies of Venezuela, islands and islets in the Caribbean Sea. It com ...
(in winter), and Greenland
Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...
(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 a phylum of protostomic invertebrate animals, whose members are known as molluscs or mollusks (). Around 76,000 extant species of molluscs are recognized, making it the second-largest animal phylum after Arthropoda. The ...
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 mollusc. The word is often applied only to those that are deemed edible and live as infauna, spending most of their lives halfway buried in the sand of the sea floor or riverbeds. Clams h ...
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 wikt:sedge, sedges. The family (biology), family is large; botanists have species description, described some 5,500 known species in about 90 ...
), "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'', a genus of aquatic ...
s", widgeon-grass (''Ruppia cirrhosa
''Ruppia cirrhosa'' is a species of aquatic plant known by the common names spiral ditchgrass and spiral tasselweed. It is native to Europe and western and Central Asia from Portugal and the British Isles to Scandinavia, the Altai, and Iran, Indi ...
''), wild celery ('' Vallisneria americana'') or wild rice
Wild rice, also called manoomin, mnomen, psíŋ, 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 and is sti ...
(''Zizania''). In winter, but less so in summer, other aquatic animals—crustacean
Crustaceans (from Latin meaning: "those with shells" or "crusted ones") are invertebrate animals that constitute one group of arthropods that are traditionally a part of the subphylum Crustacea (), a large, diverse group of mainly aquatic arthrop ...
, insect
Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...
and their larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
e and small fish
A fish (: fish or fishes) is an aquatic animal, aquatic, Anamniotes, anamniotic, gill-bearing vertebrate animal with swimming fish fin, fins and craniate, a hard skull, but lacking limb (anatomy), limbs with digit (anatomy), digits. Fish can ...
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, an Aquatic animal, aquatic bivalve mollusk in the family Dreissenidae. The species originates from the lakes of southern Russia and Ukraine, but has been accidentally Intro ...
(''Dreissena polymorpha'') in Lake Erie
Lake Erie ( ) 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 also has the shortest avera ...
, 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 aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...
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 subfamily Larinae. They are most closely related to terns and skimmers, distantly related to auks, and even more distantly related to waders. Until the 21st century, most gulls were placed ...
s or tern
Terns are seabirds in the family Laridae, subfamily Sterninae, that have a worldwide distribution and are normally found near the sea, rivers, or wetlands. Terns are treated in eleven genera in a subgroup of the family Laridae, which also ...
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 a process by which an animal casts off parts of its body to serve some beneficial purpose, either at ...
into eclipse plumage
Plumage () 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, there can b ...
, 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 and p ...
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 i ...
. The clutch
A clutch is a mechanical device that allows an output shaft to be disconnected from a rotating input shaft. The clutch's input shaft is typically attached to a motor, while the clutch's output shaft is connected to the mechanism that does th ...
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 egg, 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 vulnera ...
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
Below may refer to:
*Earth
*Ground (disambiguation)
*Soil
*Floor
* Bottom (disambiguation)
*Less than
*Temperatures below freezing
*Hell or underworld
People with the surname
* Ernst von Below (1863–1955), German World War I general
* Fred Belo ...
), 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 survey
A breeding bird survey monitors the status and trends of bird populations. Data from the survey are an important source for the range maps found in field guides. The North American Breeding Bird Survey is a joint project of the United States Geo ...
s, 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 and tufted duck. It spends the summer months breeding in Iceland ...
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 evaluated and categorized by the International Union for Conservation of Nature (IUCN) as not being a focus of wildlife conservation because the specific species is still plentiful in the wil ...
by the IUCN
The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the status ...
. 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 Conservation status, categorized as "Near Threatened" (NT) by the International Union for Conservation of Nature (IUCN) as that may be vulnerable to Endangered species, endangerment in the ne ...
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 harm. Pollution can take the form of any substance (solid, liquid, or gas) or energy (such as radioactivity, heat, sound, or light). Pollutants, the component ...
and habitat destruction
Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...
, 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.
However, it seems that greater scaup eats larger food items on average,[ and the species are ]sympatric
In biology, two closely related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter each other. An initially interbreeding population that splits into two or more distinct spe ...
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
Hunting is the Human activity, human practice of seeking, pursuing, capturing, and killing wildlife or feral animals. The most common reasons for humans to hunt are to obtain the animal's body for meat and useful animal products (fur/hide (sk ...
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 orga ...
(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
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lesser scaup
Native birds of Alaska
Native birds of Western Canada
Native birds of the Canadian Prairies
Native birds of the Northwestern United States
Birds of the Dominican Republic
Birds of Haiti
lesser scaup
lesser scaup