Anser is a waterfowlgenus that includes the grey geese and the white geese. It belongs to the true goose and swansubfamily of Anserinae under the family of Anatidae.[2] The genus has a Holarctic distribution, with at least one species breeding in any open, wet habitats in the subarctic and cool temperate regions of the Northern Hemisphere in summer. Some also breed farther south, reaching into warm temperate regions. They mostly migrate south in winter, typically to regions in the temperate zone between the January 0 °C (32 °F) and 5 °C (41 °F) isotherms.
The species of this genus span nearly the whole range of true goose shapes and sizes. The largest are the bean, greylag and swan geese at up to around 4 kg (9 lb) in weight (with domestic forms far exceeding this), and the smallest are the lesser white-fronted and Ross's geese, which ranges from about 1.3 to 2.3 kg (3–5 lb).[3]
All have legs and feet that are pink, or orange, and bills that are pink, orange, or black. All have white under- and upper-tail coverts, and several have some extent of white on their heads. The neck, body and wings are grey or white, with black or blackish primary—and also often secondary—remiges (pinions). The three species of "white geese" (emperor, snow and Ross's geese) were formerly treated as a separate genus Chen, but are now generally included in Anser. The closely related "black" geese in the genus Branta differ in having black legs, and generally darker body plumage.[3]
The evolutionary relationships between Anser geese have been difficult to resolve because of their rapid radiation during the Pleistocene and frequent hybridization.[8][9] In 2016 Ottenburghs and colleagues published a study that established the phylogenetic relationships between the species by comparing exonic DNA sequences.[10]
Breeds in northern Canada, Alaska, Greenland and northern Russia; winters in contiguous United States, northern Mexico, Europe, East Asia, Iraq and near the Caspian Sea
Emperor goose, Anser canagicus – sometimes separated in Philacte
Some authorities also treat some subspecies as distinct species (notably the tundra bean goose[15][16]) or as likely future species splits (notably the Greenland white-fronted goose).[17]
Fossil record
Numerous fossil species have been allocated to this genus. As the true geese are near-impossible to assign osteologically to genus, this must be viewed with caution. It can be assumed with limited certainty that European fossils from known inland sites belong into Anser. As species related to the Canada goose have been described from the Late Miocene onwards in North America too, sometimes from the same localities as the presumed grey geese, it casts serious doubt on the correct generic assignment of the supposed North American fossil geese.[18][19][20]Heterochen = Anser pratensis seems to differ profoundly from other species of Anser and might be placed into a different genus; alternatively, it might have been a unique example of a grey goose adapted for perching in trees.[a][b]
†Anser atavus (Middle/Late Miocene of Bavaria, Germany) – sometimes in Cygnus
†Anser arenosus Bickart 1990 (Big Sandy Late Miocene of Wickieup, USA)
†Anser arizonae Bickart 1990 (Big Sandy Late Miocene of Wickieup, USA)
The Maltese swan Cygnus equitum was occasionally placed into Anser, and Anser condoni is a synonym of Cygnus paloregonus.[18] A goose fossil from the Early-Middle Pleistocene of El Salvador is highly similar to Anser.[21] Given its age it is likely to belong to an extant genus, and biogeography indicates Branta as other likely candidate.
?Anser scaldii Beneden 1872 nomen nudum (Late Miocene of Antwerp, Belgium) may be a shelduck.
Relationship with humans and conservation status
Two species in the genus are of major commercial importance, having been domesticated as poultry: European domesticated geese are derived from the greylag goose, and Chinese and some African domesticated geese are derived from the swan goose.
Other species have benefited from reductions in hunting since the late 19th and early 20th centuries, with most species in western Europe and North America showing marked increases in response to protection[citation needed]. In some cases, this has led to conflicts with farming, when large flocks of geese graze crops in the winter.[citation needed]
^Short (1970) considers this bird to be somewhat reminiscent of geese and swans, shelducks, and the Cairinini or "perching ducks".
^The Cairinini or "perching ducks" are now known to be a paraphyletic assemblage of miscellaneous waterfowl whose morphological similarities are the product of convergent evolution towards being able to perch in trees (Livezey 1986).
References
^"Anatidae". aviansystematics.org. The Trust for Avian Systematics. Retrieved 2023-08-05.
^ abCarboneras, Carles (1992). "Family Anatidae (Ducks, Geese and Swans)". In del Hoyo, J.; Elliott, A.; Sargatal, J. (eds.). Handbook of the Birds of the World. Vol. 1: Ostrich to Ducks. Barcelona, Spain: Lynx Edicions. pp. 536–628. ISBN84-87334-10-5.
^Brisson, Mathurin Jacques (1760). Ornithologie, ou, Méthode Contenant la Division des Oiseaux en Ordres, Sections, Genres, Especes & leurs Variétés (in French and Latin). Paris: Jean-Baptiste Bauche. Vol. 1, p. 58, Vol. 6, p. 261.
^Cramp, S. (1977): The Birds of the Western Palearctic. Oxford. ISBN0-19-857358-8
^Madge, Steve & Burn, Hilary (1987): Wildfowl : an identification guide to the ducks, geese and swans of the world. Christopher Helm, London. ISBN0-7470-2201-1
^van den Berg, Arnoud B. (2007): Lijst van Nederlandse vogelsoorten ["List of Dutch bird taxa]. [Dutch and English] PDF fulltextArchived September 29, 2007, at the Wayback Machine
^Fox, A.D.; Stroud, D.A. (2002). "Greenland White-fronted Goose". Birds of the Western Palearctic Update. 4 (2): 65–88.
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