Anser cygnoides

Life-forms

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Cladus: Avemetatarsalia
Cladus: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauriformes
Cladus: Dracohors
Cladus: Dinosauria
Ordo: Saurischia
Cladus: Eusaurischia
Subordo: Theropoda
Cladus: Neotheropoda
Cladus: Averostra
Cladus: Tetanurae
Cladus: Avetheropoda
Cladus: Coelurosauria
Cladus: Tyrannoraptora
Cladus: Maniraptoromorpha
Cladus: Maniraptoriformes
Cladus: Maniraptora
Cladus: Pennaraptora
Cladus: Paraves
Cladus: Eumaniraptora
Cladus: Avialae
Infraclassis: Aves
Cladus: Euavialae
Cladus: Avebrevicauda
Cladus: Pygostylia
Cladus: Ornithothoraces
Cladus: Ornithuromorpha
Cladus: Carinatae
Parvclassis: Neornithes
Cohors: Neognathae
Cladus: Pangalloanserae
Cladus: Galloanseres
Ordo: Anseriformes

Familia: Anatidae
Subfamilia: Anserinae
Genus: Anser
Species: Anser cygnoides
Name

Anser cygnoides (Linnaeus, 1758)
Synonyms

Anas cygnoides (protonym, "cygnoid." [abbreviation])
Cygnopsis cygnoides
Anser cygnoid
Anser chinensis (nom. inval.)

References

Linnaeus, C. 1758. Systema Naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Editio Decima, Reformata. Tomus I. Holmiæ (Stockholm): impensis direct. Laurentii Salvii. 824 pp. DOI: 10.5962/bhl.title.542 BHL p. 122 BHL Reference page.
IUCN: Anser cygnoides (Vulnerable)

Vernacular names
العربية: إوز صيني
azərbaycanca: Quruburun
български: Лебедоподобна гъска
brezhoneg: Gwaz-alarc'h
català: Oca cigne
Mìng-dĕ̤ng-ngṳ̄: Ngâng
čeština: Husa labutí
Cymraeg: Alarchŵydd
dansk: Svanegås
Deutsch: Schwanengans
English: Swan Goose
Esperanto: Cigna ansero
español: Ánsar cisne o cisnal
فارسی: غاز قونما
suomi: Joutsenhanhi
français: Oie cygnoïde
galego: Ganso cisnoide
עברית: אווז ברבורי
magyar: Kínai hattyúlúd
italiano: Oca cignoide
日本語: サカツラガン
қазақша: Қытай қазы
한국어: 개리
lietuvių: Laibasnapė žąsis
latviešu: Lielknābja zoss
монгол: Хошуу галуу
Plattdüütsch: Swaangoos
Nederlands: Zwaangans
norsk: Svanegås
Diné bizaad: Chʼah Diʼilii Bikéyahdę́ę́ʼ naalʼeełítsoh
polski: Gęś łabędzionosa
português: Ganso-africano
русский: Сухонос
саха тыла: Хара тумустаах хаас
svenska: Svangås
ไทย: ห่านเทาปากดำ
Türkçe: Çin kazı
татарча/tatarça: Кытай казы
Tiếng Việt: Ngỗng thiên nga
Vahcuengh: Roegnyanh
Bân-lâm-gú: Iá-gô
粵語: 鴻雁
中文: 鸿雁

The swan goose (Anser cygnoides) is a large goose with a natural breeding range in inland Mongolia, northernmost China, and the Russian Far East. It is migratory and winters mainly in central and eastern China. Vagrant birds are encountered in Japan and Korea (where it used to winter in numbers when it was more common), and more rarely in Kazakhstan, Laos, coastal Siberia, Taiwan, Thailand and Uzbekistan.[2][3]

While uncommon in the wild, this species has been domesticated. Introduced and feral populations of its domestic breeds occur in many places outside its natural range. The wild form is also kept in collections, and escapes are not unusual amongst feral flocks of other Anser and Branta geese.

Description
The close-up of head

The swan goose is large and long-necked for its genus, wild birds being 81–94 cm (32–37 in) long (the longest Anser goose) and weighing 2.8–3.5 kg (6.2–7.7 lb) or more (the second-heaviest Anser, after the greylag goose, A. anser). The sexes are similar, although the male is larger, with a proportionally longer bill and neck; in fact the largest females are barely as large as the smallest males. Typical measurements of the wing are 45–46 cm (18–18 in) in males, 37.5–44 cm (14.8–17.3 in) in females; the bill is about 8.7–9.8 cm (3.4–3.9 in) long in males and 7.5–8.5 cm (3.0–3.3 in) in females. The tarsus of males measures around 8.1 cm (3.2 in).[2][3] The wingspan of adult geese is 160–185 cm (63–73 in).[4]
At Moscow Zoo

The upperparts are greyish-brown, with thin light fringes to the larger feathers and a maroon hindneck and cap (reaching just below the eye). The remiges are blackish, as are the entire underwing and the white-tipped rectrices, while the upper- and undertail coverts are white. A thin white stripe surrounds the bill base. Apart from darker streaks on the belly and flanks, the underside is pale buff, being especially light on the lower head and foreneck which are sharply delimited against the maroon. In flight, the wings appear dark, with no conspicuous pattern. Uniquely among its genus, the long, heavy bill is completely black; the legs and feet, on the other hand, are orange as in most of its relatives. The eyes' irides are maroon. Juveniles are duller than adult birds, and lack the white bill base and dark streaks on the underside.[2][3]

The voice is a loud drawn-out and ascending honking aang. As a warning call, a similar but more barking honk is given two or three times in short succession.[3]

The karyotype of the swan goose is 2n=80, consisting of four pairs of macrochromosomes, 35 pairs of microchromosomes, and a pair of sex chromosomes. The two largest macrochromosome pairs as well as the Z (female) chromosome are submetacentric, while the third-largest chromosome pair is acrocentric and the fourth-largest is metacentric. The W chromosomes are acrocentric too, as are the larger microchromosomes, the smaller ones probably being telocentric. Compared to the greylag goose, there seems to have been some rearrangement on the fourth-largest chromosome pair.[5]
Ecology

It inhabits steppe to taiga and mountain valleys near freshwater, grazing on plants such as sedges (Cyperaceae), and rarely swimming. It forms small flocks outside the breeding season. In the winter, it grazes on plains and stubble fields, sometimes far from water. Birds return from the winter quarters around April, and the breeding season starts soon thereafter. It breeds as single pairs or loose groups near marshes and other wetlands, with nesting activity starting about May. The clutch is usually 5–6 but sometimes up to 8 eggs, which are laid in a shallow nest made from plants, placed directly on the ground, often on a small knoll to keep it dry. The precocial young hatch after about 28 days and become sexually mature at 2–3 years of age. Around late August/early September, the birds leave for winter quarters, where they gather in small groups to moult their worn plumage.[2][3]

The swan goose was uplisted from Near Threatened to Vulnerable on the IUCN Red List in 1992 and further to Endangered in 2000, as its population is declining due to habitat loss and excessive hunting and (particularly on the Sanjiang Plain in China) egg collecting. But new research has shown it to be not as rare as it was believed, and consequently, it was downlisted to Vulnerable status again in 2008. Still, less than 500 pairs might remain in Russia, while in Mongolia numbers are unknown though about 1,000 were seen at Ögii Lake in 1977. Favorite wintering locations in China are Lake Dongting, Lake Poyang, the Yancheng Coastal Wetlands and other locations around the lower Yangtze River, where some 60,000 individuals may be found each year – though this may be almost the entire world population. Until the 1950s, the species wintered in small numbers (up to about 100 birds annually) in Japan, but habitat destruction has driven them away. Altogether, between 60,000 and 100,000 adult Swan Geese remain in the wild today.[2][6]
Domestication

Though the majority of domestic geese are descended from the greylag goose (A. anser), two breeds are direct descendants of the swan goose: the Chinese goose and the African goose. These breeds have been domesticated since at least the mid-18th century – perhaps even (in China) since around 1000 BC. They vary considerably from their wild parent in appearance, temperament, and ability to produce meat and eggs; the most conspicuous feature is the prominent bill knob[3][7][8] and upright posture.

Charles Darwin studied goose breeds as part of his work on the theory of evolution. He noted that the external differences between Chinese geese and breeds descended from the Greylag goose belied a rather close relationship:

"The hybrids from the common and Chinese geese (A. cygnoides), species which are so different that they are generally ranked in distinct genera,[9] have often bred in this country with either pure parent, and in one single instance they have bred inter se."[10]

Conservation

The species is currently classified as Vulnerable by the IUCN based on ongoing population declines and range losses, exacerbated by recent poor breeding success and unsustainable levels of hunting. Total population was estimated as 60–90,000 individuals in 2012.[1]

References

BirdLife International. (2016). "Anser cygnoid". IUCN Red List of Threatened Species. 2016: e.T22679869A92832782. doi:10.2305/IUCN.UK.2016-3.RLTS.T22679869A92832782.en.
Carboneras, Carles (1992). del Hoyo, Josep; Elliott, Andrew; Sargatal, Jordi (eds.). Handbook of Birds of the World. Volume 1: Ostrich to Ducks. Barcelona: Lynx Edicions. p. 581. ISBN 978-84-87334-10-8.
Madge, Steve; Burn, Hilary (1987). Wildfowl: an identification guide to the ducks, geese and swans of the world. Helm Identification Guides. London: Christopher Helm. ISBN 978-0-7470-2201-5.
Ogilvie, M. A.; Young, S. (2004). Wildfowl of the World. New Holland Publishers. ISBN 978-1-84330-328-2.
Wójcik, Ewa; Smalec, Elżbieta (2008). "Description of the Anser cygnoides Goose Karyotype" (PDF). Folia Biologica. 56 (1–2): 37–42. doi:10.3409/fb56_1-2.37-42. PMID 19055023.[permanent dead link]
BirdLife International (2008). "2008 IUCN Red List status changes". Retrieved 23 May 2008.
Buckland, Roger; Guy, Gérard, eds. (2002). "Goose Production". FAO Animal Production and Health Papers. Vol. 154. ISBN 978-92-5-104862-7. PDF fulltext[permanent dead link]
Carol Ekarius (2007). Storey's Illustrated Guide to Poultry Breeds. North Adams, Massachusetts: Storey Publishing. ISBN 9781580176675.
The swan goose had been separated in the monotypic genus Cygnopsis (alternatively spelled Cycnopsis) by Johann Friedrich von Brandt in 1836, some 20 years before Darwin wrote this. Cygnopsis cygnoides essentially means "Swan lookalike", Cygnopsis signifying "looking like a swan" and cygnoides "similar to a swan".
Darwin, Charles (1859). On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. London: John Murray. p. 253.