Mergus (Genus)

Overview

Mergus^1] is the of the typical mergansers, fish-eating ducks in the seaduck subfamily (Merginae). The Hooded Merganser, often termed Mergus cucullatus, is not of this genus but closely related. The other "aberrant" merganser, the Smew (Mergellus albellus), is phylogenetically closer to goldeneyes (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 have serrated edges to their bills to 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 mollusks, and therefore have a more typical duck-bill. 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.^[2]

Species

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Auckland Islands Merganser, Mergus australis (extinct, c.1902)
Common Merganser or Goosander, Mergus merganser
Brazilian Merganser, Mergus octosetaceus
Red-breasted Merganser, Mergus serrator
Chinese Merganser, Mergus squamatus

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 millio n years ago, in Central and Eastern Europe.^[3]

The Early Oligocene booby "Sula" ronzoni was at first mistakenly believed to be a typical merganser^[4]. A Late Badenian (13-12 million years ago) fossil sometimes attributed to Mergus, found in the the Saj�v�lgyi Formation of M�trasz�l�s, Hungary, probably belongs to Mergellus^[5]. The affiliations of the mysterious "Anas" albae from the Messinian (c.7-5 million years ago) of Hungary are undetermined; it was initially believed to be a typical merganser too^[6].

Photos

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Taxonomy

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Domain: Eukaryota Whittaker & Margulis,1978 - eukaryotes
- Kingdom: Animalia Linnaeus, 1758 - animals
  - Subkingdom: Bilateria (Hatschek, 1888) Cavalier-Smith, 1983 - bilaterians
    - Branch: Deuterostomia Grobben, 1908 - Deuterostomes
      - Infrakingdom: Chordonia (Haeckel, 1874) Cavalier-Smith, 1998
        Phylum: Chordata Bateson, 1885 - Chordates
        Subphylum: Vertebrata Cuvier, 1812 - Vertebrates
        Infraphylum: Gnathostomata Auct. - Jawed Vertebrates
        Superclass: Tetrapoda Goodrich, 1930 - Tetrapods
        Class: Aves Linnaeus, 1758 - Birds
        Subclass: Neornithes Gadow, 1893
        Infraclass: Neoaves
        Superorder: Anserimorphae
        Order: Anseriformes Wagler, 1831 - Ducks, Geese
        Infraorder: Anserides
        Family: Anatidae Vigors, 1825 - Ducks and Allies
        Subfamily: Anatinae
        Tribe: Anatini
        Genus: Mergus Linnaeus, 1758 - Greater Mergansers

The Genus Mergus is further organized into finer groupings including:

Species: ZipcodeZoo has pages for 15 species and subspecies in the Genus Mergus: M. albellus (Smew) · M. albellus linnaeus · M. australis (Auckland Islands Merganser) · M. cucullatus (Hooded Merganser) · M. merganser (Common Merganser) · M. merganser americanus (Common Merganser) · M. merganser merganser · M. merganser orientalis · M. octosetaceus (Brazilian Merganser) · M. orientalis · M. serrator (Red-Breasted Merganser) · M. serrator linnaeus (Red-Breasted Goosander) · M. serrator schioleri (Red-Breasted Merganser) · M. serrator serrator (Red-Breasted Merganser) · M. squamatus (Scaly-Sided Merganser)

References

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Arnott, W.G. (1964): Notes on Gavia and Mergvs in Latin Authors. Classical Quarterly (New Series) 14(2): 249-262. First page image
G�l, Erika; H�r, J�nos; Kessler, Eug�n & K�kay, J�zsef (1998-99): K�z�ps�-mioc�n �smaradv�nyok, a M�trasz�l�s, R�k�czi-k�polna alatti �tbev�g�sb�l. I. A M�trasz�l�s 1. lel�hely [Middle Miocene fossils from the sections at the R�k�czi chapel at M�traszolos. Locality M�trasz�l�s I.]. Folia Historico Naturalia Musei Matraensis 23: 33-78. [Hungarian with English abstract] PDF fulltext
Livezey, Bradley C. (1986): A phylogenetic analysis of recent anseriform genera using morphological characters. Auk 103(4): 737-754. PDF fulltext DjVu fulltext
Ml�kovsk�, Jir� (2002a): Early Pleistocene birds of Str�nsk� sk�la, Czech Republic: 2. Absolon's cave. Sylvia 38: 19-28 [English with Czech abstract]. PDF fulltext
Ml�kovsk�, Jir� (2002b): Cenozoic Birds of the World, Part 1: Europe. Ninox Press, Prague. ISBN 80-901105-3-8 PDF fulltext

Footnotes

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^ Etymology: Latin mergus, a catch-all term for sea-going birds (see Arnott, 1964)
^ Livezey (1986)
^ Ml�kovsk� (2002a)
^ Ml�kovsk� (2002b): p.264
^ G�l et al. (1998-99)
^ Ml�kovsk� (2002b): p.124

Sources

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