Mergus is the genus containing the typical mergansers ( ), fish-eating ducks in the subfamily Anatinae.
The common merganser or goosander (Mergus merganser) and red-breasted merganser (M. serrator) have broad ranges in the northern hemisphere. The Brazilian merganser (M. octosetaceus) is a South American duck, and one of the six most threatened waterfowl in the world, with possibly fewer than 250 birds in the wild. The scaly-sided merganser or "Chinese merganser" (M. squamatus) is also an endangered species; it lives in temperate eastern Asia, breeding in the northeast and wintering further south.
The hooded merganser (Lophodytes cucullatus, formerly known as Mergus cucullatus) is not currently included in this genus but is closely related, and may be embedded within it. The other "aberrant" merganser, the smew (Mergellus albellus), previously thought to be closer to goldeneyes (Bucephala) due to the occurrence of natural hybrids, is now known to be basal to all the other mergansers from genetic analysis.
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, they do not have notches at the hind margin of their sternum, but holes surrounded by bone. The genus name is the Latin word for an unidentified waterbird mentioned by Pliny the Elder and other authors; some sources have identified the original mergus as referring to either a cormorant or Scopoli's shearwater. The type species was designated as Mergus serrator Linnaeus, 1758 (the red-breasted merganser) by Thomas Campbell Eyton in 1838.
Etymology
The genus name is a Latin word used by Pliny the Elder and other Roman authors to refer to an unspecified diving waterbird. The name goosander is older in English usage, first attested in 1622 with the spelling "gossander" and 1674 with its current spelling; it is of unknown etymology but possibly from a Scandinavian origin as "gossand", where goss is unknown, and -and is a duck.
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! Image !! Scientific name !! Common name!! Distribution
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|†Mergus australis
|Auckland Island merganser
|Auckland Islands, New Zealand (extinct ). The species identity of merganser bones from mainland New Zealand (North, South, and Stewart Islands) is unresolved.
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|†Mergus milleneri
|Chatham Island merganser
|Chatham Island, New Zealand. Extinct sometime after human settlement of the Chatham Islands,
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Fossil species
Some fossil members of this genus have been described:
- Mergus miscellus is known from the Middle Miocene Calvert Formation (Barstovian, c. 14 million years ago) of Virginia, USA.
- Mergus connectens lived in the Early Pleistocene about 2–1 million years ago, in Central and Eastern Europe. A Late Serravallian (13–12 million years ago) fossil sometimes attributed to Mergus, found in the Sajóvölgyi Formation of Mátraszőlős, Hungary, probably belongs to Mergellus.
References
Further reading
- Mlíkovský, Jirí (2002b): Cenozoic Birds of the World, Part 1: Europe. Ninox Press, Prague.<!-- This should be treated with extreme caution as regards merging of species. Splits are usually good though. See also critical review in The Auk 121: 623–627 here http://www.findarticles.com/p/articles/mi_qa3793/is_200404/ai_n9396879 -->