Common Merganser
Encyclopedia
The Common Merganser or Goosander (Eurasian) Mergus merganser is a large duck
, of rivers and lakes of forested areas of Europe
, northern and central Asia
, and North America
. It eats fish and nests in holes in trees. John James Audubon
called this bird the "Buff-breasted Merganser" in his book The Birds of America.
It is 58–72 cm (22.8–28.3 in) long with a 78–97 cm (30.7–38.2 in) wingspan, and a weight of 0.9 –; males average slightly larger than females but with some overlap. Like other species
in the genus
Mergus
, it has a crest of longer head feathers, but these usually lie smoothly rounded behind the head, not normally forming an erect crest. Adult males in breeding plumage are easily distinguished, the body white with a variable salmon-pink tinge, the head black with an iridescent green gloss, the rump and tail grey, and the wings largely white on the inner half, black on the outer half. Females, and males in "eclipse" (non-breeding plumage, July to October) are largely grey, with a reddish-brown head, white chin, and white secondary feathers on the wing. Juveniles (both sexes) are similar to adult females but also show a short black-edged white stripe between the eye and bill. The bill and legs are red to brownish-red, brightest on adult males, dullest on juveniles.
, differing in only minor detail:
s, worms, insect larvae, and amphibians; more rarely, small mammals and birds may be taken. As in other birds with the character, the salmon-pink tinge shown variably by males is probably diet-related, obtained from the carotenoid
pigments present in some crustaceans and fish. When not diving for food, they are usually seen swimming on the water surface, or resting on rocks in midstream or hidden among riverbank vegetation, or (in winter) on the edge of floating ice.
In most places, the Common Merganser is nearly as much a salt-water as a fresh-water frequenter. In larger streams and rivers, they float down with the stream for a couple of miles, and either fly back again or more commonly fish their way back, diving incessantly the whole way. In smaller streams, they are present in pairs or smaller groups, and they float down, twisting round and round in the rapids, or fishing vigorously in some deep pool near the foot of some waterfall or rapid. When floating leisurely, they position themselves in water similar to ducks. But they swim deep in water like Cormorants too, especially when swimming upstream. They often sit on some rock in the middle of the water, similar to Cormorants, often half-opening their wings to the sun. In order to rise from water, they flap along the surface for many yards. Once they are airborne the flight is strong and rapid. They often fish in as a group forming a semicircle and driving the fish into a shallow, where they are captured easily. Their
ordinary voice is a low, harsh croak but during the breeding season they (including the young one) makes a plaintive, soft whistle. Generally, they are wary and one or more birds stay on sentry duty to warn the flock on the approach of danger. And when disturbed, they often disgorge food before moving. Though they move clumsily on land, they resort to running when pressed, assuming a very upright position similar to penguins, and falling and stumbling frequently.
Nesting
is normally in a tree cavity, thus it requires mature forest as its breeding habitat; they also readily use large nest boxes where provided, requiring an entrance hole 15 cm diameter. In places devoid of trees (like Central Asian mountains), they use holes in cliffs and steep, high banks, sometimes at considerable distances from the water. The female lays 6–17 (most often 8–12) white to yellowish eggs, and raises one brood in a season. The ducklings are taken by their mother in her bill to rivers or lakes immediately after hatching, where they feed on freshwater invertebrates and small fish fry, fledging when 60–70 days old. The young are sexually mature at two years old.
The species is a partial migrant
, with birds moving away from areas where rivers and major lakes freeze in the winter, but resident where waters remain open. Eastern North American birds move south in small groups to the United States
wherever ice free conditions exist on lakes and rivers; on the milder Pacific coast, they are permanent residents. Scandinavia
n and Russia
n birds also migrate southwards, but western Europe
an birds, and a few in Japan
, are largely resident. In some populations, the males also show distinct moult migration, leaving the breeding areas as soon as the young hatch to spend the summer (June to September) elsewhere. Notably, most of the western European male population migrates north to estuaries in Finnmark
in northern Norway
(principally Tanafjord
) to moult, leaving the females to care for the ducklings. Much smaller numbers of males also use estuaries in eastern Scotland
as a moulting area.
Within western Europe, there has been a marked southward spread from Scandinavia
in the breeding range since about 1850, colonising Scotland
in 1871, England
in 1941, and also a strong increase in the population in the Alps
. A small breeding population has recently been established in Ireland.
The Goosander is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
) applies.
Duck
Duck is the common name for a large number of species in the Anatidae family of birds, which also includes swans and geese. The ducks are divided among several subfamilies in the Anatidae family; they do not represent a monophyletic group but a form taxon, since swans and geese are not considered...
, of rivers and lakes of forested areas of 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...
, northern and central Asia
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
, and North America
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...
. It eats fish and nests in holes in trees. John James Audubon
John James Audubon
John James Audubon was a French-American ornithologist, naturalist, and painter. He was notable for his expansive studies to document all types of American birds and for his detailed illustrations that depicted the birds in their natural habitats...
called this bird the "Buff-breasted Merganser" in his book The Birds of America.
It is 58–72 cm (22.8–28.3 in) long with a 78–97 cm (30.7–38.2 in) wingspan, and a weight of 0.9 –; males average slightly larger than females but with some overlap. Like other species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...
Mergus
Mergus
Mergus is the genus of the typical mergansers, fish-eating ducks in the seaduck subfamily . The Hooded Merganser, often termed Mergus cucullatus, is not of this genus but closely related...
, it has a crest of longer head feathers, but these usually lie smoothly rounded behind the head, not normally forming an erect crest. Adult males in breeding plumage are easily distinguished, the body white with a variable salmon-pink tinge, the head black with an iridescent green gloss, the rump and tail grey, and the wings largely white on the inner half, black on the outer half. Females, and males in "eclipse" (non-breeding plumage, July to October) are largely grey, with a reddish-brown head, white chin, and white secondary feathers on the wing. Juveniles (both sexes) are similar to adult females but also show a short black-edged white stripe between the eye and bill. The bill and legs are red to brownish-red, brightest on adult males, dullest on juveniles.
Taxonomy
There are three subspeciesSubspecies
Subspecies in biological classification, is either a taxonomic rank subordinate to species, ora taxonomic unit in that rank . A subspecies cannot be recognized in isolation: a species will either be recognized as having no subspecies at all or two or more, never just one...
, differing in only minor detail:
- M. m. merganser Linnaeus, 1758. Throughout northern Europe and northern Asia.
- M. m. orientalis GouldJohn GouldJohn Gould was an English ornithologist and bird artist. The Gould League in Australia was named after him. His identification of the birds now nicknamed "Darwin's finches" played a role in the inception of Darwin's theory of evolution by natural selection...
, 1845 (syn. M. m. comatus SalvadoriTommaso SalvadoriCount Adelardo Tommaso Salvadori Paleotti was an Italian zoologist and ornithologist.Salvadori was born in Porto San Giorgio, son of Count Luigi Salvadori and Ethel. He took an early interest in birds and published a catalogue of the birds of Sardinia in 1862...
, 1895). Central Asian mountains. Slightly larger than M. m. merganser, with a slenderer bill. - M. m. americanus CassinJohn CassinJohn Cassin was an American ornithologist.He is considered to be one of the giants of American ornithology, and was America's first taxonomist, describing 198 birds not previously mentioned by Alexander Wilson and John James Audubon...
, 1852. North America. Bill broader-based than in than M. m. merganser, and a black bar crossing the white inner wing (visible in flight) on males.
Behaviour
Like the other mergansers, these fish-feeding ducks have serrated edges to their bills to help them grip their prey; they are therefore often known as "sawbills". In addition to fish, they take a wide range of other aquatic prey, such as molluscs, crustaceanCrustacean
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...
s, worms, insect larvae, and amphibians; more rarely, small mammals and birds may be taken. As in other birds with the character, the salmon-pink tinge shown variably by males is probably diet-related, obtained from the carotenoid
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...
pigments present in some crustaceans and fish. When not diving for food, they are usually seen swimming on the water surface, or resting on rocks in midstream or hidden among riverbank vegetation, or (in winter) on the edge of floating ice.
In most places, the Common Merganser is nearly as much a salt-water as a fresh-water frequenter. In larger streams and rivers, they float down with the stream for a couple of miles, and either fly back again or more commonly fish their way back, diving incessantly the whole way. In smaller streams, they are present in pairs or smaller groups, and they float down, twisting round and round in the rapids, or fishing vigorously in some deep pool near the foot of some waterfall or rapid. When floating leisurely, they position themselves in water similar to ducks. But they swim deep in water like Cormorants too, especially when swimming upstream. They often sit on some rock in the middle of the water, similar to Cormorants, often half-opening their wings to the sun. In order to rise from water, they flap along the surface for many yards. Once they are airborne the flight is strong and rapid. They often fish in as a group forming a semicircle and driving the fish into a shallow, where they are captured easily. Their
ordinary voice is a low, harsh croak but during the breeding season they (including the young one) makes a plaintive, soft whistle. Generally, they are wary and one or more birds stay on sentry duty to warn the flock on the approach of danger. And when disturbed, they often disgorge food before moving. Though they move clumsily on land, they resort to running when pressed, assuming a very upright position similar to penguins, and falling and stumbling frequently.
Nesting
Bird nest
A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American Robin or Eurasian Blackbird, or the elaborately woven hanging nest of the...
is normally in a tree cavity, thus it requires mature forest as its breeding habitat; they also readily use large nest boxes where provided, requiring an entrance hole 15 cm diameter. In places devoid of trees (like Central Asian mountains), they use holes in cliffs and steep, high banks, sometimes at considerable distances from the water. The female lays 6–17 (most often 8–12) white to yellowish eggs, and raises one brood in a season. The ducklings are taken by their mother in her bill to rivers or lakes immediately after hatching, where they feed on freshwater invertebrates and small fish fry, fledging when 60–70 days old. The young are sexually mature at two years old.
The species is a partial migrant
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...
, with birds moving away from areas where rivers and major lakes freeze in the winter, but resident where waters remain open. Eastern North American birds move south in small groups to the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
wherever ice free conditions exist on lakes and rivers; on the milder Pacific coast, they are permanent residents. Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
n and Russia
Russia
Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...
n birds also migrate southwards, but 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...
an birds, and a few in 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...
, are largely resident. In some populations, the males also show distinct moult migration, leaving the breeding areas as soon as the young hatch to spend the summer (June to September) elsewhere. Notably, most of the western European male population migrates north to estuaries in Finnmark
Finnmark
or Finnmárku is a county in the extreme northeast of Norway. By land it borders Troms county to the west, Finland to the south and Russia to the east, and by water, the Norwegian Sea to the northwest, and the Barents Sea to the north and northeast.The county was formerly known as Finmarkens...
in northern Norway
Norway
Norway , officially the Kingdom of Norway, is a Nordic unitary constitutional monarchy whose territory comprises the western portion of the Scandinavian Peninsula, Jan Mayen, and the Arctic archipelago of Svalbard and Bouvet Island. Norway has a total area of and a population of about 4.9 million...
(principally Tanafjord
Tanafjord
Tanafjord or Tanafjorden is a fjord in Finnmark, Norway. Its orientation is mainly north-south, spanning approximately 66 kilometres from the Smalfjord settlement in the south to Barents Sea in the north. The fjord separates the Nordkinn Peninsula in the west from the Varanger Peninsula in the...
) to moult, leaving the females to care for the ducklings. Much smaller numbers of males also use estuaries in eastern Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
as a moulting area.
Status and conservation
Overall, the species is not threatened, though illegal persecution by game fishing interests is a problem in some areas.Within western Europe, there has been a marked southward spread from Scandinavia
Scandinavia
Scandinavia is a cultural, historical and ethno-linguistic region in northern Europe that includes the three kingdoms of Denmark, Norway and Sweden, characterized by their common ethno-cultural heritage and language. Modern Norway and Sweden proper are situated on the Scandinavian Peninsula,...
in the breeding range since about 1850, colonising Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
in 1871, England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
in 1941, and also a strong increase in the population in the Alps
Alps
The Alps is one of the great mountain range systems of Europe, stretching from Austria and Slovenia in the east through Italy, Switzerland, Liechtenstein and Germany to France in the west....
. A small breeding population has recently been established in Ireland.
The Goosander is one of the species to which the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA
AEWA
The Agreement on the Conservation of African-Eurasian Migratory Waterbirds is the largest of its kind developed so far under the Bonn Convention. It was concluded on 16 June 1995 at The Hague, the Netherlands and entered into force on 1 November 1999 after the required number of at least fourteen...
) applies.
External links
- Goosander videos, photos & sounds on the Internet Bird Collection