Swan Goose

Swan Goose

Kingdom
Phylum
Class
Order
Family
Genus
SPECIES
Anser cygnoides
Population size
60-90 thou
Life Span
10 yrs
WEIGHT
2.8-3.5 kg
LENGTH
81-94 cm
WINGSPAN
160-185 cm

Swan geese are large and long-necked water birds. They are greyish-brown in color, with thin light fringes to the larger feathers and a maroon hindneck and cap (reaching just below the eye). Apart from darker streaks on the belly and flanks, their underside is pale buff. Uniquely among its genus, the long, heavy bill is completely black in color and a thin white stripe surrounds the bill base; 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.

Distribution

Swan geese breed in Mongolia, northernmost China, and southeastern Russia. They are migratory and winter mainly in central and eastern China. Vagrant birds are encountered in Japan and Korea (where they used to winter), and more rarely in Kazakhstan, Laos, coastal Siberia, Taiwan, Thailand, and Uzbekistan. These birds inhabit taiga, grasslands, steppes and mountain valleys near freshwater lakes and fast-flowing rivers. In winter, they can be found in marshes, estuaries, plains, and rice-fields.

Swan Goose habitat map

Climate zones

Habits and Lifestyle

Swan geese are social birds and form small flocks outside the breeding season. They are crepuscular and forage in the morning and evening. These birds rarely swim and most of their time is spent grazing on plants. Swan geese migrate twice a year; spring migration occurs in late February-early April and the autumn migration starts in August and lasts until mid-September. Prior to autumn migration, the birds usually gather in small groups to molt their worn plumage. The voice of Swan geese is a loud drawn-out and ascending honking "aang". They also produce a similar but more barking honk two or three times in short succession as a warning call.

Seasonal behavior

Diet and Nutrition

Swan geese are herbivores (graminivores, folivores). They feed mainly on grasses, leaves, roots, sedges and water plants. They will also consume seeds and berries.

Mating Habits

MATING BEHAVIOR
REPRODUCTION SEASON
April-May
INCUBATION PERIOD
28 days
INDEPENDENT AGE
10-11 weeks
FEMALE NAME
goose
MALE NAME
gander
BABY NAME
gosling
BABY CARRYING
5-8 eggs

Swan geese are serially monogamous and form pair-bonds that last only within one breeding season. They return from the winter grounds around April, and the breeding season starts soon thereafter. Swan geese breed as single pairs or loose groups near marshes and other wetlands and start nesting in May. The clutch is usually 5-8 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. Incubation lasts about 28 days done only by a female while the male guards her and the nest. Goslings are precocial; they hatch fully-developed and with eyes open. They fledge 10-11 weeks after hatching and become reproductively mature at 2 to 3 years of age.

Population

Population threats

Populations of Swan geese are declining due to habitat loss, excessive hunting and (particularly on the Sanjiang Plain in China) egg collecting. In Mongolia, these birds suffer from fires, droughts, and overgrazing.

Population number

According to the IUCN Red List, the total Swan goose population size is around 60,000-90,000 individuals. Specific population numbers have been estimated in such areas: in Korea - around 50-1,000 individuals on migration and around 50-1,000 wintering individuals; in Yangtze River wetlands - 87,544 individuals. Overall, currently, Swan geese are classified as Vulnerable (VU) on the IUCN Red List and their numbers today are decreasing.

Ecological niche

Due to their grazing habits, Swan geese play an important role in their ecosystem; they provide soil aeration and new habitat for plants which helps new seeds to grow better.

Domestication

While uncommon in the wild, the Swan goose has been domesticated and introduced and feral populations of its domestic breeds occur in many places outside its natural range. There are two breeds that 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 and upright posture.

DOMESTICATION STATUS Domesticated

Fun Facts for Kids

  • Today wild Swan geese are often kept in collections because they have become uncommon in the wild.
  • Migrating two times a year, each time Swan geese cover around 2,500-3,000 kilometers of travel.
  • Favorite wintering locations of Swan geese in China are Lake Dongting, Lake Poyang, the Yancheng Coastal Wetlands and other locations around the lower Yangtze River, where almost the entire wild Swan goose population may be found each year; this is around 60,000 geese in total!
  • During hard and long migration flights, geese show excellent teamwork; they encourage each other with honks to maintain the speed and when the leading goos gets tired, another one will take take the guiding position.

References

1. Swan Goose on Wikipedia - https://en.wikipedia.org/wiki/Swan_goose
2. Swan Goose on The IUCN Red List site - https://www.iucnredlist.org/species/22679869/92832782

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