Lesser Scaup
Encyclopedia
The Lesser Scaup 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 give it credit to the female's discordant scaup call as the name's source. It is apparently a very close relative of the Holarctic
Greater Scaup
or "bluebill" (A. marila), with which it forms a superspecies
.
s) are about 7.5–7.9 in (19.1–20.1 cm) in males and 7.3–7.8 in (18.5–19.8 cm) in females; the tarsus
is about 1.4–1.5 in (3.6–3.8 cm) long, and the bill 1.4–1.7 in (3.6–4.3 cm). The wingspan is 68–78 cm (26.8–30.7 in).
The adult males (drakes) in alternate plumage have a black, effervescent head and a small tuft at the hindcrown, a black breast, a whitish-grey back and wings with darker vermiculations and black outer and geyish-brown inner primary remiges. The underparts are white with some 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, 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 black "nail" at the tip and grey feet; the drakes have a bright yellow iris
, while that of females is orange or amber and that of immatures is brown. Downy
hatchlings look much like those of related species, with dark brown upperparts and pale buff underparts, chin, supercilium
and back spots.
These birds are not very vocal, at least compared to dabbling ducks. 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.
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. The bill may give a hint; in the Lesser Scaup it has a stronger curve on the upperside than in the Greater, resulting in a distal part that looks somewhat flattened and wide in the Lesser Scaup – hence the vernacular name "broadbill". If the birds fly, 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.
Lesser Scaup females show the characteristic darker iris (bright yellow in Greater Scaup males and females) at closer distances. 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 best trait – if the primary remiges are not visible – is the shape of the head: in the Greater Scaup drake, the forehead is usually quite massive, 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 alternate 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.
Hybridization
Particularly in the case of vagrant birds in Europe, the identification is complicated by similar-looking Aythya
hybrids. 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:
In theory, each and every Aythya species is able to produce potentially 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.
s and marsh
pond
s in tundra
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
valley and on the Old Crow Flats
. These birds migrate
south (mostly via the Central
and Mississippi Flyway
s) when the young are fledged and return in 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-Canadian
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 USA 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
. The first documented British
record was a first-winter male at Chasewater
, Staffordshire
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
Japan
, possibly China
, and – for the first time on 18 January 2000 – in the Marianas, as well as in Ecuador
, Surinam, Trinidad
and Venezuela
(in winter), and Greenland
(in summer).
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
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.
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
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.
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
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.
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.
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
status.
The causes for this stark – though not threatening, as of 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 items – which shifted winterwards due to global warming
, without the ducks being able to adapt. In this regard, it is alternatively or additionally possible that Great 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 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
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.
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
n diving duck
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 the diverse and very large Anatidae family that includes ducks, geese, and swans....
that migrates south as far as Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
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 give it credit to the female's discordant scaup call as the name's source. It is apparently a very close relative of the Holarctic
Holarctic
The Holarctic ecozone refers to the habitats found throughout the northern continents of the world as a whole. This region is divided into the Palearctic, consisting of Northern Africa and all of Eurasia, with the exception of Southeast Asia and the Indian subcontinent, and the Nearctic,...
Greater Scaup
Greater Scaup
The Greater Scaup , just Scaup in Europe, or colloquially known as "Bluebill", for its bright blue bill, is small compared to other diving ducks, however it is larger than the closely related Lesser Scaup...
or "bluebill" (A. marila), with which it forms a superspecies
Superspecies
A superspecies is a group of at least two more or less distinctive species with approximately parapatric distributions. Not all species complexes, whether cryptices or ring species are superspecies, and vice versa, but many are...
.
Description
Adults are 38–48 cm (15–18.9 in) long, 41.7–43 cm (16.4–16.9 in) on average. The species can weigh 454–1089 g (1–2.4 lb); males weigh 820 g (1.8 lb) on average and weigh noticeably less, at 730 g (1.6 lb) on average. Wing lengths (not wingspanWingspan
The wingspan of an airplane or a bird, is the distance from one wingtip to the other wingtip. For example, the Boeing 777 has a wingspan of about ; and a Wandering Albatross caught in 1965 had a wingspan of , the official record for a living bird.The term wingspan, more technically extent, is...
s) are about 7.5–7.9 in (19.1–20.1 cm) in males and 7.3–7.8 in (18.5–19.8 cm) in females; the tarsus
Tarsus (skeleton)
In tetrapods, the tarsus is a cluster of articulating bones in each foot situated between the lower end of tibia and fibula of the lower leg and the metatarsus. In the foot the tarsus articulates with the bones of the metatarsus, which in turn articulate with the bones of the individual toes...
is about 1.4–1.5 in (3.6–3.8 cm) long, and the bill 1.4–1.7 in (3.6–4.3 cm). The wingspan is 68–78 cm (26.8–30.7 in).
The adult males (drakes) in alternate plumage have a black, effervescent head and a small tuft at the hindcrown, a black breast, a whitish-grey back and wings with darker vermiculations and black outer and geyish-brown inner primary remiges. The underparts are white with some 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, 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 black "nail" at the tip and grey feet; the drakes have a bright yellow iris
Iris (anatomy)
The iris is a thin, circular structure in the eye, responsible for controlling the diameter and size of the pupils and thus the amount of light reaching the retina. "Eye color" is the color of the iris, which can be green, blue, or brown. In some cases it can be hazel , grey, violet, or even pink...
, while that of females is orange or amber and that of immatures is brown. Downy
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 padding, used in goods such as jackets, bedding,...
hatchlings look much like those of related species, with dark brown upperparts and pale buff underparts, chin, supercilium
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. Also known as an "eyebrow", it is distinct from the eyestripe, which is a line which runs...
and back spots.
These birds are not very vocal, at least compared to dabbling ducks. Hens give the namesake discordant scaup, scaup call; in courtship drakes produce weak whistles. Hens vocalize more often than those of the Greater Scaup
Greater Scaup
The Greater Scaup , just Scaup in Europe, or colloquially known as "Bluebill", for its bright blue bill, is small compared to other diving ducks, however it is larger than the closely related Lesser Scaup...
– particularly during flight –, but their call is weaker, a guttural brrtt, brrtt.
Identification
Lesser Scaup are often hard to distinguish from the Greater ScaupGreater Scaup
The Greater Scaup , just Scaup in Europe, or colloquially known as "Bluebill", for its bright blue bill, is small compared to other diving ducks, however it is larger than the closely related Lesser Scaup...
when direct comparison is not possible, but in North America a large scaup
Aythya
Aythya is a genus of diving ducks. It has twelve described species.Aythya shihuibas was described from the Late Miocene of China. An undescribed prehistoric species is known only from Early Pleistocene fossil remains found at Dursunlu, Turkey; it might however be referrable to a paleosubspecies of...
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. The bill may give a hint; in the Lesser Scaup it has a stronger curve on the upperside than in the Greater, resulting in a distal part that looks somewhat flattened and wide in the Lesser Scaup – hence the vernacular name "broadbill". If the birds fly, 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.
Ring-necked Duck
The Ring-necked Duck is a smaller diving duck from North America.The adult male is similar in color pattern to the Eurasian Tufted Duck, its relative. It has a grey bill with a white band, a shiny purple head, a white breast, yellow eyes and a dark grey back...
(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
Aythya is a genus of diving ducks. It has twelve described species.Aythya shihuibas was described from the Late Miocene of China. An undescribed prehistoric species is known only from Early Pleistocene fossil remains found at Dursunlu, Turkey; it might however be referrable to a paleosubspecies of...
hybrids. 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
Tufted Duck
The Tufted Duck, Aythya fuligula, is a medium-sized diving duck with a population of close to one million birds.- Description :The adult male is all black except for white flanks and a blue-grey bill. It has an obvious head tuft that gives the species its name.The adult female is brown with paler...
(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 sequenceDNA sequenceThe sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...
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 introgressionIntrogressionIntrogression, also known as introgressive hybridization, in genetics is the movement of a gene from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species...
. - 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 RedheadRedhead (duck)The Redhead is a medium-sized diving duck, 37 cm long with an 84 cm wingspan.The adult male has a blue bill, a red head and neck, a black breast, yellow eyes and a grey back. The adult female has a brown head and body and a darker bluish bill with a black tip.The breeding habitat is...
(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 fertile
Fertile
The term fertile describes a condition whereby organisms are able to produce physically healthy offspring.Fertile may also refer to:...
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.
Distribution and migration
Their breeding habitat is inland lakeLake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...
s and marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
pond
Pond
A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens, water features and koi ponds; all designed for aesthetic ornamentation as landscape or architectural...
s in tundra
Tundra
In physical geography, tundra is a biome where the tree growth is hindered by low temperatures and short growing seasons. The term tundra comes through Russian тундра from the Kildin Sami word tūndâr "uplands," "treeless mountain tract." There are three types of tundra: Arctic tundra, alpine...
from Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...
through western Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
to western Montana
Montana
Montana is a state in the Western United States. The western third of Montana contains numerous mountain ranges. Smaller, "island ranges" are found in the central third of the state, for a total of 77 named ranges of the Rocky Mountains. This geographical fact is reflected in the state's name,...
; few breed east of James Bay
James Bay
James Bay is a large body of water on the southern end of Hudson Bay in Canada. Both bodies of water extend from the Arctic Ocean. James Bay borders the provinces of Quebec and Ontario; islands within the bay are part of Nunavut...
and the Great Lakes
Great Lakes
The Great Lakes are a collection of freshwater lakes located in northeastern North America, on the Canada – United States border. Consisting of Lakes Superior, Michigan, Huron, Erie, and Ontario, they form the largest group of freshwater lakes on Earth by total surface, coming in second by volume...
. 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
McKenzie River
The McKenzie River is a tributary of the Willamette River in western Oregon in the United States. It drains part of the Cascade Range east of Eugene and flows into the southernmost end of the Willamette Valley. It is named for Donald MacKenzie, a Scottish Canadian fur trader...
valley and on the Old Crow Flats
Old Crow Flats
Old Crow Flats is a wetland complex in northern Yukon, Canada. It is north of the Arctic Circle and south of the Beaufort Sea, and is nearly surrounded by mountains. The site is protected by the Yukon Wildlife Ordinance and Migratory Birds Convention Act...
. These birds migrate
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...
south (mostly via the Central
Central Flyway
The Central Flyway is a bird migration route that generally follows the Great Plains in the United States and Canada. The main endpoints of the flyway include central Canada and the region surrounding the Gulf of Mexico; the migration route tends to narrow considerably in the Platte River and...
and Mississippi Flyway
Mississippi Flyway
The Mississippi Flyway is a bird migration route that generally follows the Mississippi River in the United States and the Mackenzie River in Canada. The main endpoints of the flyway include central Canada and the region surrounding the Gulf of Mexico...
s) when the young are fledged and return in 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
River
A river is a natural watercourse, usually freshwater, flowing towards an ocean, a lake, a sea, or another river. In a few cases, a river simply flows into the ground or dries up completely before reaching another body of water. Small rivers may also be called by several other names, including...
s and sheltered coastal lagoon
Lagoon
A lagoon is a body of shallow sea water or brackish water separated from the sea by some form of barrier. The EU's habitat directive defines lagoons as "expanses of shallow coastal salt water, of varying salinity or water volume, wholly or partially separated from the sea by sand banks or shingle,...
s and bay
Bay
A bay is an area of water mostly surrounded by land. Bays generally have calmer waters than the surrounding sea, due to the surrounding land blocking some waves and often reducing winds. Bays also exist as an inlet in a lake or pond. A large bay may be called a gulf, a sea, a sound, or a bight...
s between the US-Canadian
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
border and northern Colombia
Colombia
Colombia, officially the Republic of Colombia , is a unitary constitutional republic comprising thirty-two departments. The country is located in northwestern South America, bordered to the east by Venezuela and Brazil; to the south by Ecuador and Peru; to the north by the Caribbean Sea; to the...
, including Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
, the West Indies and Bermuda
Bermuda
Bermuda is a British overseas territory in the North Atlantic Ocean. Located off the east coast of the United States, its nearest landmass is Cape Hatteras, North Carolina, about to the west-northwest. It is about south of Halifax, Nova Scotia, Canada, and northeast of Miami, Florida...
. Wintering Lesser Scaup are typically found in freshwater
Freshwater
Fresh water is naturally occurring water on the Earth's surface in ice sheets, ice caps, glaciers, bogs, ponds, lakes, rivers and streams, and underground as groundwater in aquifers and underground streams. Fresh water is generally characterized by having low concentrations of dissolved salts and...
or slightly brackish habitat and unlike Greater Scaup
Greater Scaup
The Greater Scaup , just Scaup in Europe, or colloquially known as "Bluebill", for its bright blue bill, is small compared to other diving ducks, however it is larger than the closely related Lesser Scaup...
rarely are seen offshore when unfrozen freshwater habitat is available. They may even spend the winter on lakes in park
Park
A park is a protected area, in its natural or semi-natural state, or planted, and set aside for human recreation and enjoyment, or for the protection of wildlife or natural habitats. It may consist of rocks, soil, water, flora and fauna and grass areas. Many parks are legally protected by...
s, as long as they are not harassed, and will occur even on smallish Caribbean
Caribbean
The Caribbean is a crescent-shaped group of islands more than 2,000 miles long separating the Gulf of Mexico and the Caribbean Sea, to the west and south, from the Atlantic Ocean, to the east and north...
islands such as Grand Cayman
Grand Cayman
Grand Cayman is the largest of the three Cayman Islands and the location of the nation's capital, George Town. In relation to the other two Cayman Islands, it is approximately 75 miles southwest of Little Cayman and 90 miles southwest of Cayman Brac.-Geography:Grand Cayman encompasses 76% of...
. Thousands winter each year on the Topolobampo
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 , reporting a 2005 census population of 6,032 inhabitants....
lagoons in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
, and even in the southernmost major wintering location – Ciénaga Grande de Santa Marta
Ciénaga Grande de Santa Marta
The Ciénaga Grande de Santa Marta is the largest of the swampy marshes located between the Magdalena River and the Sierra Nevada de Santa Marta, weakly separated from the Caribbean Sea by a narrow strait....
in Colombia – hundreds of birds can be seen. In Central America
Central America
Central America is the central geographic region of the Americas. It is the southernmost, isthmian portion of the North American continent, which connects with South America on the southeast. When considered part of the unified continental model, it is considered a subcontinent...
, 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
Rocky Mountains
The Rocky Mountains are a major mountain range in western North America. The Rocky Mountains stretch more than from the northernmost part of British Columbia, in western Canada, to New Mexico, in the southwestern United States...
region of the northwestern USA 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
Europe is, by convention, one of the world's seven continents. Comprising the westernmost peninsula of Eurasia, Europe is generally 'divided' from Asia to its east by the watershed divides of the Ural and Caucasus Mountains, the Ural River, the Caspian and Black Seas, and the waterways connecting...
. The first documented British
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
record was a first-winter male at Chasewater
Chasewater
Chasewater is a 3-square-kilometre reservoir in the parish of Burntwood, in the district of Lichfield, Staffordshire, England. Originally known as Norton Pool, it was created as a canal feeder reservoir in the 18th Century and remains the largest in use in the region today.-History:Work on...
, Staffordshire
Staffordshire
Staffordshire is a landlocked county in the West Midlands region of England. For Eurostat purposes, the county is a NUTS 3 region and is one of four counties or unitary districts that comprise the "Shropshire and Staffordshire" NUTS 2 region. Part of the National Forest lies within its borders...
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
Hawaiian Islands
The Hawaiian Islands are an archipelago of eight major islands, several atolls, numerous smaller islets, and undersea seamounts in the North Pacific Ocean, extending some 1,500 miles from the island of Hawaii in the south to northernmost Kure Atoll...
Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
, possibly China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, and – for the first time on 18 January 2000 – in the Marianas, as well as in Ecuador
Ecuador
Ecuador , officially the Republic of Ecuador is a representative democratic republic in South America, bordered by Colombia on the north, Peru on the east and south, and by the Pacific Ocean to the west. It is one of only two countries in South America, along with Chile, that do not have a border...
, Surinam, Trinidad
Trinidad
Trinidad is the larger and more populous of the two major islands and numerous landforms which make up the island nation of Trinidad and Tobago. It is the southernmost island in the Caribbean and lies just off the northeastern coast of Venezuela. With an area of it is also the fifth largest in...
and Venezuela
Venezuela
Venezuela , officially called the Bolivarian Republic of Venezuela , is a tropical country on the northern coast of South America. It borders Colombia to the west, Guyana to the east, and Brazil to the south...
(in winter), and Greenland
Greenland
Greenland is an autonomous country within the Kingdom of Denmark, located between the Arctic and Atlantic Oceans, east of the Canadian Arctic Archipelago. Though physiographically a part of the continent of North America, Greenland has been politically and culturally associated with Europe for...
(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 mollusks such as musselMussel
The common name mussel is used for members of several families of clams or bivalvia mollusca, from saltwater and freshwater habitats. These groups have in common a shell whose outline is elongated and asymmetrical compared with other edible clams, which are often more or less rounded or oval.The...
s and clam
Clam
The word "clam" can be applied to freshwater mussels, and other freshwater bivalves, as well as marine bivalves.In the United States, "clam" can be used in several different ways: one, as a general term covering all bivalve molluscs...
s, as well as seeds and other parts of aquatic plants like sedges and bulrushes (Cyperaceae
Cyperaceae
Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
), "pondweed
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 plants...
s", Widgeon-grass (Ruppia cirrhosa
Ruppia cirrhosa
Ruppia cirrhosa is a species of aquatic plant known by the common name spiral ditchgrass. It is native to the Americas and Europe, where it grows in freshwater bodies, such as lakes. It is a thread-thin, grasslike perennial herb which grows from a rhizome anchored in the wet substrate. It produces...
), Wild Celery
Wild celery
Wild celery is a plant in the family Hydrocharitaceae . Contrary to the implications of its name, wild celery bears little to no resemblance to the celery used as a vegetable. Wild celery grows under water and is consumed by various animals, including the canvasback...
(Vallisneria americana) or wild rice
Wild rice
Wild rice is four species of grasses forming the genus Zizania, and the grain which can be harvested from them. The grain was historically gathered and eaten in both North America and China...
(Zizania). In winter, but less so in summer, other aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...
animals – crustacean
Crustacean
Crustaceans form a very large group of arthropods, usually treated as a subphylum, which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles. The 50,000 described species range in size from Stygotantulus stocki at , to the Japanese spider crab with a leg span...
, insect
Insect
Insects are a class of living creatures within the arthropods that have a chitinous exoskeleton, a three-part body , three pairs of jointed legs, compound eyes, and two antennae...
and their larva
Larva
A larva 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...
e and small fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate 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...
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
Zebra mussel
The zebra mussel, Dreissena polymorpha, is a small freshwater mussel. This species was originally native to the lakes of southeast Russia being first described in 1769 by a German zoologist Peter Simon Pallas in the Ural, Volga and Dnieper rivers. They are still found nearby, as Pontic and Caspian...
(Dreissena polymorpha) in Lake Erie
Lake Erie
Lake Erie is the fourth largest lake of the five Great Lakes in North America, and the tenth largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. It is bounded on the north by the...
, 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 feeder
Filter feeders are 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 feeding are clams, krill, sponges, baleen whales, and many fish and some sharks. Some birds,...
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
Cyperaceae
Cyperaceae are a family of monocotyledonous graminoid flowering plants known as sedges, which superficially resemble grasses or rushes. The family is large, with some 5,500 species described in about 109 genera. These species are widely distributed, with the centers of diversity for the group...
, sometimes in small loose groups and not rarely next to colonies of gull
Gull
Gulls are birds in the family Laridae. They are most closely related to the terns and only distantly related to auks, skimmers, and more distantly to the waders...
s or tern
Tern
Terns are seabirds in the family Sternidae, previously considered a subfamily of the gull family Laridae . They form a lineage with the gulls and skimmers which in turn is related to skuas and auks...
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
Moult
In biology, moulting or molting , also known as sloughing, shedding, or for some species, ecdysis, is the manner in which an animal routinely casts off a part of its body , either at specific times of year, or at specific points in its life cycle.Moulting can involve the epidermis , pelage...
into eclipse plumage, 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
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 padding, used in goods such as jackets, bedding,...
s. Breeding begins in May, but most birds nest only in June, later than usual for North American waterfowl
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....
. The clutch
Clutch (eggs)
A clutch of eggs refers to all the eggs produced by birds or reptiles, often at a single time, particularly those laid in a nest.In birds, destruction of a clutch by predators, , results in double-clutching...
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
Fledge
Fledge is the stage in a young bird's life when the feathers and wing muscles are sufficiently developed for flight. It also describes the act of a chick's parents raising it to a fully grown state...
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 20th century. During breeding bird surveyBreeding 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 Geological Survey and the Canadian Wildlife Service...
s, Lesser and Greater Scaup
Greater Scaup
The Greater Scaup , just Scaup in Europe, or colloquially known as "Bluebill", for its bright blue bill, is small compared to other diving ducks, however it is larger than the closely related Lesser 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
Least Concern
Least Concern is an IUCN category assigned to extant taxon or lower taxa which have been evaluated but do not qualify for any other category. As such they do not qualify as threatened, Near Threatened, or Conservation Dependent...
by the IUCN. An increase of the decline is liable to result in an uplisting to Near Threatened
Near Threatened
Near Threatened is a conservation status assigned to species or lower taxa that may be considered threatened with extinction in the near future, although it does not currently qualify for the threatened status...
or even Vulnerable
Vulnerable species
On 30 January 2010, the IUCN Red List of Threatened Species identified 9694 Vulnerable species, subspecies and varieties, stocks and sub-populations.-References:...
status.
The causes for this stark – though not threatening, as of 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
Pollution is the introduction of contaminants into a natural environment that causes instability, disorder, harm or discomfort to the ecosystem i.e. physical systems or living organisms. Pollution can take the form of chemical substances or energy, such as noise, heat or light...
and habitat destruction
Habitat destruction
Habitat destruction is the process in which natural habitat is rendered functionally unable to support the species present. In this process, the organisms that previously used the site are displaced or destroyed, reducing biodiversity. Habitat destruction by human activity mainly for the purpose of...
, 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
Global warming
Global warming refers to the rising average temperature of Earth's atmosphere and oceans and its projected continuation. In the last 100 years, Earth's average surface temperature increased by about with about two thirds of the increase occurring over just the last three decades...
, without the ducks being able to adapt. In this regard, it is alternatively or additionally possible that Great 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 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
Hunting is the practice of pursuing any living thing, usually wildlife, for food, recreation, or trade. In present-day use, the term refers to lawful hunting, as distinguished from poaching, which is the killing, trapping or capture of the hunted species contrary to applicable law...
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.
Further reading
- Farrand, John Jr. & National Audubon SocietyNational Audubon SocietyThe National Audubon Society is an American non-profit environmental organization dedicated to conservation. Incorporated in 1905, Audubon is one of the oldest of such organizations in the world and uses science, education and grassroots advocacy to advance its conservation mission...
(1983): The Audubon Society master guide to birding. Alfred A. Knopf, New York. ISBN 0517032880 - Svensson, Lars; Zetterström, Dan; Mullarney, Killian & Grant, P. J. (1999): Collins bird guide. Harper & Collins, London. ISBN 0-00-219728-6
External links
- Avibase Links in turn to Flickr Handguide
- Lesser Scaup: Cornell Lab of Ornithology
- Lesser Scaup: USGS Patuxent Bird Identification Infocenter
- An article and photograph
- The Nature Conservancy's Species profile for the lesser scaup
- Lesser Scaup Information and Photos: South Dakota Birds and Birding
- Greater and Lesser Scaups, Environment Canada