ChenBoie, 1822 (but see text) CygnopsisBrandt, 1836 CycnopsisAgassiz, 1846 (emendation) EulabeiaReichenbach, 1852 PhilacteBannister, 1870 HeterochenShort, 1970 (but see text)
Anser is awaterfowlgenus that includes thegrey geese and thewhite geese. It belongs to the truegoose andswansubfamily ofAnserinae under the family ofAnatidae.[2] The genus has aHolarctic distribution, with at least one species breeding in any open, wet habitats in thesubarctic and cooltemperate regions of the Northern Hemisphere in summer. Some also breed farther south, reaching into warm temperate regions. They mostlymigrate 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 thebean,greylag andswan geese at up to around 4 kg (9 lb) in weight (withdomestic forms far exceeding this), and the smallest are thelesser white-fronted andRoss's geese, which range 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, black, or patterned in a combination of these colours. All have white under- and upper-tailcoverts, and some 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 andRoss's geese) were formerly treated as a separate genusChen, but are now generally included inAnser, as their exclusion would leaveAnserparaphyletic with thebar-headed gooseA. indicus beingbasal in the genus.[4] The closely related "black" geese in the genusBranta differ in having black legs, and generally darker body plumage.[3]
The evolutionary relationships betweenAnser geese have been difficult to resolve because of their rapidradiation during thePleistocene and frequenthybridisation.[9][10] In 2016 Ottenburghs and colleagues published a study that established the phylogenetic relationships between the species by comparingexonic DNA sequences;[4] a further analysis by the same group in 2023 refined the relationships in the bean goose complex, withpink-footed goose closest totaiga bean goose, rather thantundra bean goose as had been thought before.[11]
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
Breeds in northern Russia, Finland, Norway and Sweden; winters in East Asia, near the Caspian Sea, and in southeastern and northwestern Europe
Some authorities also treat somesubspecies as potential future species splits, notably the Greenland white-fronted gooseA. albifrons flavirostris.[12] The three east Asian subspecies of the bean goose complex (currently treated asA. fabalis johanseni, A. fabalis middendorfii, andA. serrirostris serrirostris) also await genetic analysis to discern their affinities.[11]
Numerousfossil species have been allocated to this genus. As the true geese are near-impossible to assignosteologically to genus, this must be viewed with caution. It can be assumed with limited certainty that European fossils from known inland sites belong intoAnser. As species related to theCanada goose have been described from the LateMiocene onwards inNorth 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.[13][14][15]Heterochen =Anser pratensis seems to differ profoundly from other species ofAnser 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 atavusFraas 1870 (Middle/Late Miocene of Bavaria, Germany) – sometimes inCygnus
†Anser arenosusBickart 1990 (Late Miocene of Arizona, USA)
†Anser arizonaeBickart 1990 (Late Miocene of Arizona, USA)
†Anser djuktaiensisZelenkov & Kurochkin 2014 (Late Pleistocene of Yakutia, Russia)
†Anser subanserJanossy 1982 (Pleistocene of Europe)
TheMaltese swanCygnus equitum was occasionally placed intoAnser, andAnser condoni is a synonym ofCygnus paloregonus.[13] A goose fossil from the early-middle Pleistocene ofEl Salvador is highly similar toAnser;[16] given its age it is likely to belong to an extant genus, thoughbiogeography indicatesBranta as another potential candidate.
Anser scaldiiBeneden 1872 nomen nudum (Late Miocene of Antwerp, Belgium), based on a right humerus, was reassigned to the modernBrent goose and suggested to be reworked from later Pleistocene orHolocene deposits.[17]
Two species in the genus are of major commercial importance, having been domesticated aspoultry: Europeandomesticated geese are derived from thegreylag goose, and Chinese and some African domesticated geese are derived from theswan 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 theCairinini or "perching ducks".
^TheCairinini or "perching ducks" are now known to be aparaphyletic assemblage of miscellaneous waterfowl whosemorphological similarities are the product ofconvergent evolution towards being able to perch in trees (Livezey 1986).
^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.
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