''Mergus'' is the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of the typical mergansers ( ) fish-eating

duck Duck is the common name for numerous species of waterfowl in the family (biology), family Anatidae. Ducks are generally smaller and shorter-necked than swans and goose, geese, which are members of the same family. Divided among several subfam ...

s in the subfamily

Anatinae 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 ...

. The genus name is a Latin word used by

Pliny the Elder Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...

and other

Roman Roman or Romans most often refers to: *Rome, the capital city of Italy *Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of Roman civilization *Epistle to the Romans, shortened to Romans, a letter w ...

authors to refer to an unspecified waterbird. The

common merganser The common merganser (North American) or goosander (Eurasian) (''Mergus merganser'') is a large sea duck of rivers and lakes in forested areas of Europe, Asia, and North America. The common merganser eats mainly fish. It nests in holes in trees ...

(''Mergus merganser'') and

red-breasted merganser The red-breasted merganser (''Mergus serrator'') is a duck species that is native to much of the Northern Hemisphere. The red breast that gives the species its common name is only displayed by males in breeding plumage. Individuals fly rapidly ...

(''M. serrator'') have broad ranges in the northern hemisphere. The

Brazilian merganser The Brazilian merganser (''Mergus octosetaceus'') is a South American diving duck in the ''Mergus'' genus. It is one of the most threatened waterfowl species in the world, with possibly fewer than 250 birds in the wild and a small number kept ...

(''M. octosetaceus'') is a South American duck, and one of the six most

threatened A threatened species is any species (including animals, plants and fungi) which is vulnerable to extinction in the near future. Species that are threatened are sometimes characterised by the population dynamics measure of ''critical depensatio ...

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 ...

in the world, with possibly fewer than 250 birds in the wild. The

scaly-sided merganser The scaly-sided merganser or Chinese merganser (''Mergus squamatus'') is an endangered typical merganser (genus ''Mergus''). It lives in Manchuria and extreme Southeast Siberia, breeding in the north and wintering in the south. Description Thi ...

or "Chinese merganser" (''M. squamatus'') is an

endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching, inv ...

species. It lives in

temperate In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...

East Asia, breeding in the north and wintering in the south. The hooded merganser (''Lophodytes cucullatus'', formerly known as ''Mergus cucullatus'') is not of this genus but is closely related. The other "aberrant" merganser, the

smew The smew (''Mergellus albellus'') is a species of duck and is the only living member of the genus ''Mergellus''. ''Mergellus'' is a diminutive of ''Mergus'' and ''albellus'' is from Latin ''albus'' "white". This genus is closely related to ''Me ...

(''Mergellus albellus''), is

phylogenetically In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical data ...

closer to

goldeneye ''GoldenEye'' is a 1995 spy film, the seventeenth in the List of James Bond films, ''James Bond'' series produced by Eon Productions, and the first to star Pierce Brosnan as the fictional Secret Intelligence Service, MI6 agent James Bond (lit ...

s (''Bucephala''). Although they are seaducks, most of the mergansers prefer riverine habitats, with only the red-breasted merganser being common at sea. These large fish-eaters typically have black-and-white, brown or green hues in their plumage, and most have somewhat shaggy crests. All have serrated edges to their long and thin bills that help them grip their prey. Along with the smew and hooded merganser, they are therefore often known as "sawbills". The goldeneyes, on the other hand, feed mainly on

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, and therefore have a more typical duck-bill. ''Mergus'' ducks are also classified as "diving ducks" because they submerge completely in looking for food. In other traits, however, the genera ''Mergus'', ''Lophodytes'', ''Mergellus'', and ''Bucephala'' are very similar: uniquely among all

Anseriformes Anseriformes is an order (biology), 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 f ...

, they do not have notches at the hind margin of their

sternum The sternum (: sternums or sterna) or breastbone is a long flat bone located in the central part of the chest. It connects to the ribs via cartilage and forms the front of the rib cage, thus helping to protect the heart, lungs, and major bl ...

, but holes surrounded by bone.

Taxonomy

The

''Mergus'' was introduced in 1758 by the Swedish naturalist

Carl Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

in the tenth edition of his ''

Systema Naturae ' (originally in Latin written ' with the Orthographic ligature, ligature æ) is one of the major works of the Sweden, Swedish botanist, zoologist and physician Carl Linnaeus (1707–1778) and introduced the Linnaean taxonomy. Although the syste ...

''. The genus name is the

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 ...

word for an unidentified waterbird mentioned by

and other authors; some sources have identified the original ''mergus'' as referring to either a

cormorant Phalacrocoracidae is a family of approximately 40 species of aquatic birds commonly known as cormorants and shags. Several different classifications of the family have been proposed, but in 2021 the International Ornithologists' Union (IOU) ado ...

Scopoli's shearwater Scopoli's shearwater (''Calonectris diomedea'') is a seabird in the petrel family Procellariidae. It breeds on rocky islands and on steep coasts in the Mediterranean but outside the breeding season it forages in the Atlantic. It is brownish grey ...

. The

type species In International_Code_of_Zoological_Nomenclature, zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the spe ...

was designated as ''Mergus serrator''

Linnaeus Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...

, 1758 (the

) by Thomas Campbell Eyton in 1838.

Recent species

The genus contains four living species and two recently extinct species.

Fossil species

Some

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserve ...

members of this genus have been described: * ''Mergus miscellus'' is known from the Middle

Miocene The Miocene ( ) is the first epoch (geology), geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and mea ...

Calvert Formation The Calvert Formation is a Formation (geology), geologic formation in Maryland, Virginia, and Delaware. It preserves fossils dating back to the early to middle Miocene, Miocene epoch of the Neogene Period (geology), period. It is one of the three ...

(

Barstovian The Barstovian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 16,300,000 to 13,600,000 years BP, a period of . It is usua ...

, c.14

million years ago Million years ago, abbreviated as Mya, Myr (megayear) or Ma (megaannum), is a unit of time equal to (i.e. years), or approximately 31.6 teraseconds. Usage Myr is in common use in fields such as Earth science and cosmology. Myr is also used w ...

) of

Virginia Virginia, officially the Commonwealth of Virginia, is a U.S. state, state in the Southeastern United States, Southeastern and Mid-Atlantic (United States), Mid-Atlantic regions of the United States between the East Coast of the United States ...

, USA. * ''Mergus connectens'' lived in the

Early Pleistocene The Early Pleistocene is an unofficial epoch (geology), sub-epoch in the international geologic timescale in chronostratigraphy, representing the earliest division of the Pleistocene Epoch within the ongoing Quaternary Period. It is currently esti ...

about 2–1 million years ago, in Central and Eastern Europe. The Early

Oligocene The Oligocene ( ) is a geologic epoch (geology), epoch of the Paleogene Geologic time scale, Period that extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that defin ...

booby A booby is a seabird in the genus ''Sula'', part of the family Sulidae. Boobies are closely related to the gannets (''Morus''), which were formerly included in ''Sula''. Systematics and evolution The genus ''Sula'' was introduced by the Fre ...

''"Sula" ronzoni'' was at first mistakenly believed to be a typical merganser. A Late

Serravallian The Serravallian is, in the geologic timescale, an List of time periods, age or a stage (stratigraphy), stage in the middle Miocene epoch (geology), Epoch/series (stratigraphy), Series, which spans the time between 13.82 annum, Ma and 11.63 Ma (m ...

(13–12 million years ago) fossil sometimes attributed to ''Mergus'', found in the Sajóvölgyi Formation of Mátraszőlős,

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

, probably belongs to ''Mergellus''. The affiliations of ''"Anas" albae'' from the

Messinian The Messinian is in the geologic timescale the last age or uppermost stage of the Miocene. It spans the time between 7.246 ± 0.005 Ma and 5.333 ± 0.005 Ma (million years ago). It follows the Tortonian and is followed by the Zanclean, the fir ...

(c. 7–5 million years ago) of Hungary are undetermined; it was initially believed to be a typical merganser too.Mlíkovský (2002b): p. 124

Taxonomy

Recent species

Fossil species

References

Further reading