Swan goose (Anser cygnoides)

Synonyms: Cygnopsis cygnoides
GenusAnser (1)
SizeLength: 81 – 94 cm (2)

The swan goose is classified as Vulnerable (VU) on the IUCN Red List (1), and listed on Appendix I and II of the Convention on Migratory Species (3).

The swan goose (Anser cygnoides) is a large goose with a striking, bi-coloured neck. The back of the neck and crown are dark brown whilst the front is a light cream (2). The bill is black in colour, with a white band across the forehead separating it from the dark crown (2). The plumage on the back is also brown (2). These geese give a resounding ‘honk’ alarm call (2).

Breeding grounds occur in eastern Russia, Mongolia and northeast China. These geese then migrate to wintering sites along the east Chinese coast, Japan, South Korea and Taiwan (3). The swan goose was previously considered to be common but underwent substantial declines during the 19th and early 20th centuries (4).

Breeding habitat includes wetlands along river valleys and lakes with reedbeds and islands in the steppe (5), whilst in winter swan geese are found on more coastal habitats including estuaries and tidal flats (2).

The breeding season begins in May, nests are constructed within thick grasses and reeds, often on river islands to protect them from predation (4). Swan geese in Mongolia nest in colonies. Females lay a clutch of between three and nine eggs; once hatched, different broods often come together into flocks and float downstream, en mass, to broader lakes and valleys (4). Moulting also occurs on the breeding grounds, usually at the end of July, but dependent on the weather condition that year (5). The swan goose then migrates to China, Taiwan, Japan and South Korea, where it spends the winter (4).

Feeding usually occurs after nightfall, and the diet changes with the seasons and location of populations. In the breeding grounds, sedges (Carex species) constitute the majority of the diet, whilst in autumn a large number of berries are consumed (4).

Habitat loss, particularly at breeding sites, is one of the major causes of the documented decline in populations of the swan goose. Wetlands are highly vulnerable ecosystems that are often threatened by development and pollution (2). Hunting also poses a threat to survival, as does the collection of eggs that occurs in some areas of China. Indeed, egg collection and habitat destruction have resulted in a 90 percent decrease in the number of swans and geese that breed in the Sanjiang Plain in China over the last 30 years (2). The breeding population of swan geese in Mongolia is particularly threatened by fire, drought, and overgrazing (5).

The swan goose is protected by law in Russia, Mongolia, South Korea and some Chinese provinces (2), and is also included on Appendix I of the Convention on Migratory Species (CMS) (3). The breeding and moulting sites of the swan goose in central and eastern Mongolia are located within protected areas (5). A Swan Goose Conservation Programme has been established in collaboration with the Russian Goose and Swan Study Group (RGSSG) and the Japanese Association for Wild Geese Protection (JAWGP), which is involved in coordinating research and conservation programmes involving this species (6).

For more information on the swan goose: 

Authenticated (28/08/08) by Dr. Sundev Gombobaatar, Associate Professor, Zoology Department, National University of Mongolia. Vice President, Mongolian Ornithological Society.

  1. IUCN Red List (March, 2011)
  2. BirdLife International (May, 2008)
  3. Convention on Migratory Species (August, 2008)
  4. BirdLife International. (2001) Threatened Birds of Asia: the BirdLife International Red Data Book. BirdLife International, Cambridge, UK.
  5. Gombobaatar, S. (2008) Pers. comm.
  6. Wildfowl and Wetlands Trust (August, 2003)