Swan goose

Source: Wikipedia, the free encyclopedia.

Swan goose
Anser cygnoides cygnoides in China
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Anseriformes
Family: Anatidae
Genus: Anser
Species:
A. cygnoides
Binomial name
Anser cygnoides
Subspecies

A. c. cygnoid (Linnaeus, 1758)
A. c. domesticus[verification needed] – Chinese and African geese

Breeding (northern areas) in orange and wintering (southern areas) ranges in blue
Synonyms
  • Anser cygnoides (Linnaeus, 1758) [orth. error]
  • Anas cygnoides Linnaeus, 1758
  • Cycnopsis cygnoides (lapsus)
  • Cygnopsis cygnoides (Linnaeus, 1758)

The swan goose (Anser cygnoides) is a large goose with a natural breeding range in inland Mongolia, Northeast 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

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

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

telocentric. Compared to the greylag goose, there seems to have been some rearrangement on the fourth-largest chromosome pair.[5]

Ecology

It inhabits

moult their worn plumage.[2][3]

The swan goose was uplisted from

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.

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 an endangered species by the IUCN based on ongoing population declines and range losses, exacerbated by recent poor breeding success and unsustainable levels of hunting.[1] Total population was estimated as 36–43,500 individuals in 2023.[1]

Gallery

References

  1. ^
    doi:10.2305/IUCN.UK.2016-3.RLTS.T22679869A228564177.en
    .
  2. ^
    ISBN 978-84-87334-10-8
    .
  3. ^
    ISBN 978-0-7470-2201-5
    .
  4. ISBN 978-1-84330-328-2
    .
  5. PMID 19055023.[permanent dead link
    ]
  6. ^ "Anser cygnoides (Swan goose)". Animal Diversity Web.
  7. ISBN 978-92-5-104862-7. PDF fulltext[permanent dead link
    ]
  8. ISBN 9781580176675
    .
  9. 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".
  10. ^ 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.

External links

Wikimedia Commons has media related to Anser cygnoides.
Wikispecies has information related to Anser cygnoides.

Retrieved from "https://en.wikipedia.org/w/index.php?title=Swan_goose&oldid=1207419893"