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Anser cygnoidesswan goose

By Gretchen Luchauer

Geographic Range

Swan geese are native to eastern Asia. However, humans introduced a group to Europe in the 1700's. Descendants of this group currently live in urban areas of central Europe. Asian swan geese have a semiannual migration. They spent summers in Mongol Daguur, a steppe region where the borders of Russia, Mongolia, and China meet. In autumn, swan geese fly south to the Yangtze River Basin. Swan geese may choose to fly directly south or they head southeast and stage at coastal locations. Many staging geese rest at the Yalu River Estuary located on the border of China and North Korea, about half way between Mongol Daguur and the Yangtze River Basin. (Batbayar, et al., 2011; Fox, et al., 2008; Randler, 2007)

Habitat

Swan geese always reside on the coasts or in lakes, rivers, ponds, or any other wetland environment near grassland regions. In the summer they live in higher altitudes in the Mongol Daguur highland steppe. This region is about 610 to 821 meters above sea level. In winter, they migrate south and for lower altitudes. During this migration, birds spend time at any body of water they fly near, and they often spend time on marine coasts and estuaries at sea level. During winter, swan geese stay near Shengjin Lake, Yangtze River, or a few other sites along the Yangtze River floodplain. (Batbayar, et al., 2011; "Important Bird Areas Facts Sheet", 2009; Zhang, et al., 2010)

  • Range elevation
    610 to 821 m
    2001.31 to 2693.57 ft

Physical Description

Swan geese are large geese that grow 81 to 94 cm long. Their wingspan varies from 160 to 185 cm, and their average weight is 3150 g. Birds have bi-colored necks and heads. Adults have black fleshy knobs at the base of their stocky black bills. They have orange feet. From the breast to the keel, the plumage becomes increasingly dark brown. Their wings and backs are the same dark brown as their keels. Their bodies are white past their feet, but their tails are dark brown. Males and females look almost identical but males grow slightly larger than females. Like other ducks, geese, and swans (Anatidae), swan geese have large external penises. Unlike mammals, sperm flows along the outer grooves of these copulatory organs. (Benstead, et al., 2008; Rohwer, 1988; Tellkamp, 2004)

  • Average mass
    3150 g
    111.01 oz
  • Range length
    81 to 94 cm
    31.89 to 37.01 in
  • Range wingspan
    160 to 185 cm
    62.99 to 72.83 in

Reproduction

Swan geese mate during the spring. Similar to other geese, they perform ritualistic displays to signal to other geese. They shake and preen to attract mates, warn competition, and to prevent hybridization. If a female finds a display pleasing she may choose to bond with the male. Swan geese form monogamous pair bonds that last most of the mating season. Occasionally, males fight to win the admiration of more desirable females. They fight by physically attacking each other until one of them gives up and runs away. The remaining male typically gets the desirable female and better territory. Paired birds display by head bobbing to reinforce their bond. It is unknown if swan geese mate for life. (Randler, 2007; Tellkamp, 2004)

The breeding season begins around late April and early May. Females lay an average of 5 to 6 eggs per season. One clutch is produced per season, but females lay for multiple seasons. Goslings begin hatching near the end of May. Swan geese grow at similar rates as other geese. Juveniles reach fledging stage at about 8 weeks and are capable of independent living at about 12 weeks, but they normally choose to stay with their parents longer than this. Both males and females reach sexually maturity between 1 to 3 years old. It is unknown whether this behavior is advantageous for young Asian populations because most studies of reproductive behavior have relied upon introduced European populations. (Randler, 2007; Rohwer, 1988; Tellkamp, 2004)

  • Breeding interval
    Swan geese only reproduce once yearly.
  • Breeding season
    Swan geese reproduce from late April to early May.
  • Average eggs per season
    5.5
  • Range time to hatching
    28 to 34 days
  • Average fledging age
    8 weeks
  • Range time to independence
    9 to 12 weeks
  • Range age at sexual or reproductive maturity (female)
    1 to 3 years
  • Range age at sexual or reproductive maturity (male)
    1 to 3 years

Female swan geese typically construct nests and brood eggs while their male partners become more alert and chase intruders. Young swan geese hatch at a precocial stage and can both walk and feed themselves. The parents work together to protect hatchlings from harm. Mothers spend more time teaching offspring where to graze, and how to escape predation while fathers remain vigilant to protect the entire family unit. Post fledgling offspring often spend extra time with their parents. These birds actually become more alert than their parents are at this time. (Randler, 2007; Rohwer, 1988)

  • Parental Investment
  • precocial
  • male parental care
  • female parental care
  • pre-hatching/birth
    • provisioning
      • female
    • protecting
      • male
  • pre-weaning/fledging
    • provisioning
      • female
    • protecting
      • male
      • female
  • pre-independence
    • protecting
      • male
      • female
  • post-independence association with parents
  • extended period of juvenile learning
  • inherits maternal/paternal territory

Lifespan/Longevity

Little is known about how long swan geese live in the wild because they are difficult to individually track and can live many years. However, wild birds have their highest mortality in their first four weeks of life. Domestic birds usually live an average of 20 years if properly cared for and have been known to live for up to 40 years. (Batbayar, et al., 2011; "Keeping Chinese Swan Geese as Pets", 2014; Randler, 2007)

  • Average lifespan
    Status: captivity
    40 years
  • Average lifespan
    Status: captivity
    20 years

Behavior

Swan geese have very basic daily schedules. They are a crepuscular species that sleeps around noon and midnight every day. While they feed both in the morning and evening, they feed more extensively in the evening. Overall, they spent about half their day grazing and grubbing for plants. They feed more in mid-winter to prepare for the mating season. These birds have social hierarchies in small groups. Dominance is usually established by the strongest male and this behavior tends to help males gain access to higher quality female partners and grazing areas. Swan geese migrate semiannually. Their spring migration lasts from late February to early April while their autumn migration lasts from early August to mid-September. Each migration typically consists of a total of 2,500-3,000 kilometers of travel. (Batbayar, et al., 2011; Fox, et al., 2008)

Swan geese pair off for breeding, but they have few if any territorial disputes with other animals, including other swan geese. On the Necker River (in Europe), 13 bird families were observed staying and feeding on a 1.1 kilometer lawn. In late summer, many individuals group together while they molt and prepare for autumn migration. Almost the entire wild swan goose population winters at the Yangtze River floodplain. As many as 30,000 geese may stay at one lake during the winter. (Benstead, et al., 2008; Randler, 2007; Zhang, et al., 2010)

  • Range territory size
    (Colony) 0 to 10 km^2

Home Range

Swan geese form large colonies, and occupy entire lakes during the winter. In the summer small groups of geese stay at medium to large lakes. They graze over large areas, but they leave if food is scarce or they are threatened. ("Important Bird Areas Facts Sheet", 2009; Tellkamp, 2004; Zhang, et al., 2010)

Communication and Perception

Swan geese are the most auditory of the domesticated goose species. Birds are very talkative, and produce deep “honking” sounds. Sight and tactile senses are also important for perception in geese. Birds from the same group often respond to each by head bobbing and slightly higher pitched honks. These geese like to honk with their mating partners, producing loud duets. Sometimes geese also preen each other as a sign of affection. Strangers will often pose and display to each other to establish a social hierarchy. Rarely, one goose will physically attack another to establish dominance. Usually the attacking goose wins. ("Keeping Chinese Swan Geese as Pets", 2014; Tellkamp, 2004)

Food Habits

Swan geese feed similarly to other true geese. Their short stocky bills, with the nail at the front, assists in their grazing lifestyle. Usually, birds will feed on terrestrial grasses, roots, seeds and water plants that grow near wetlands. In their winter habitats in the Yangtze River Basin, swan geese choose to graze on either Canary grass (Phalaris arundinacea) or grub for Vallisneria spiralis rhizomes. Domestic swan geese eat rice and grains in addition to grass and water plants. (Fox, et al., 2008; Randler, 2007; Xu, et al., 2014)

  • Plant Foods
  • leaves
  • roots and tubers
  • seeds, grains, and nuts

Predation

The main predators of swan geese are humans. Many locals hunt these birds for sport or food even though they are legally protected in many Asian countries. Russia has the largest amount of uncontrolled goose hunting. The birds are wary and fly if threatened, but also can be cryptic if unable to flee. Natural predators are not described. ("Important Bird Areas Facts Sheet", 2009)

  • Anti-predator Adaptations
  • cryptic
  • Known Predators
    • humans (Homo sapien)

Ecosystem Roles

Swan geese provide soil aeration and new habitat for both grasses and water plants. Their root grubbing kills standing vegetation but the associated soil upheaval provides air, water, and area for new grass seeds to germinate and grow. Their consumption of surface plants provide sunlight to shallow aquatic grasses. (Fox, et al., 2008)

Species Used as Host
  • Swan geese have no known host species.
Mutualist Species
  • Swan geese are not known to be mutualistic with any other species.
Commensal/Parasitic Species
  • It is unknown whether wild swan geese have parasitic species.

Economic Importance for Humans: Positive

Swan geese are one of several goose species to be domesticated. They are the second most common domestic goose after greylag geese. Although there is very little documentation of the domestication of swan geese, anthropologists have discovered pottery depicting geese that is over 3,000 years old. ("Credo Reference", 2000)

Domestic swan geese live in rural areas all over the world. They are an important food source in China where they are commercially raised in factory farms. Birds are used for eggs, meat, and feathers. Their down provides good stuffing for bedding and clothes and wing feathers make excellent quills. Several researchers have been studying the genetics of swan geese to find how to reduce non-laying broodiness in commercial geese. ("Credo Reference", 2000; Xu, et al., 2014)

  • Positive Impacts
  • pet trade
  • food
  • body parts are source of valuable material
  • research and education

Economic Importance for Humans: Negative

Most swan geese are harmless to humans and they are one of the tamer species. However, there are instances of breeding geese that attack and bite people and animals who get too close to their eggs. Wild swan geese live in areas that have many avian influenza outbreaks. So far none are known to have the H1N1 virus. Scientists are concerned that this virus outbreak may harm humans more if swan geese become susceptible. (Batbayar, et al., 2011; Randler, 2007)

  • Negative Impacts
  • injures humans
    • bites or stings

Conservation Status

Swan geese are listed as vulnerable on the IUCN Red List, but they do not show up on many other important conservation lists. It is believed that wild swan geese populations are declining due to destruction of both their summer breeding sites and their winter feeding sites. (Benstead, et al., 2008; "Important Bird Areas Facts Sheet", 2009; Zhang, et al., 2010)

Goose summer nesting sites in Mongol Daguur are highly prone to steppe fires. These fires usually originate from Russia, and easily burn off vegetation that swan geese feed on. Mongol Daguur is nationally protected in Mongolia, but this region suffers from poor federal management. Human activities, such as livestock grazing and mineral mining are disturbing all species that live in Mongol Daguur. ("Important Bird Areas Facts Sheet", 2009)

The destruction and degradation of swan goose habitat is worse in their wintering sites in the Yangtze River floodplain. The Three Gorges Dam in Yangtze River delays peak monsoon flows in the summer. This reduces water levels, which reduces the survivability of Vallisnaria and Potamogeton, two important aquatic plants that serve as primary winter food sources for many geese. (Zhang, et al., 2010)

Contributors

Gretchen Luchauer (author), Indiana University-Purdue University Fort Wayne, Mark Jordan (editor), Indiana University-Purdue University Fort Wayne, Tanya Dewey (editor), University of Michigan-Ann Arbor.

Glossary

Palearctic

living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.

World Map

acoustic

uses sound to communicate

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

bog

a wetland area rich in accumulated plant material and with acidic soils surrounding a body of open water. Bogs have a flora dominated by sedges, heaths, and sphagnum.

brackish water

areas with salty water, usually in coastal marshes and estuaries.

chemical

uses smells or other chemicals to communicate

choruses

to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species

coastal

the nearshore aquatic habitats near a coast, or shoreline.

colonial

used loosely to describe any group of organisms living together or in close proximity to each other - for example nesting shorebirds that live in large colonies. More specifically refers to a group of organisms in which members act as specialized subunits (a continuous, modular society) - as in clonal organisms.

crepuscular

active at dawn and dusk

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

dominance hierarchies

ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates

duets

to jointly display, usually with sounds in a highly coordinated fashion, at the same time as one other individual of the same species, often a mate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

estuarine

an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.

female parental care

parental care is carried out by females

folivore

an animal that mainly eats leaves.

food

A substance that provides both nutrients and energy to a living thing.

freshwater

mainly lives in water that is not salty.

granivore

an animal that mainly eats seeds

herbivore

An animal that eats mainly plants or parts of plants.

holarctic

a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.

World Map

Found in northern North America and northern Europe or Asia.

introduced

referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

male parental care

parental care is carried out by males

marsh

marshes are wetland areas often dominated by grasses and reeds.

migratory

makes seasonal movements between breeding and wintering grounds

monogamous

Having one mate at a time.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pelagic

An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).

pet trade

the business of buying and selling animals for people to keep in their homes as pets.

riparian

Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).

saltwater or marine

mainly lives in oceans, seas, or other bodies of salt water.

seasonal breeding

breeding is confined to a particular season

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

sexual ornamentation

one of the sexes (usually males) has special physical structures used in courting the other sex or fighting the same sex. For example: antlers, elongated tails, special spurs.

social

associates with others of its species; forms social groups.

soil aeration

digs and breaks up soil so air and water can get in

stores or caches food

places a food item in a special place to be eaten later. Also called "hoarding"

suburban

living in residential areas on the outskirts of large cities or towns.

swamp

a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.

tactile

uses touch to communicate

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

terrestrial

Living on the ground.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

urban

living in cities and large towns, landscapes dominated by human structures and activity.

visual

uses sight to communicate

young precocial

young are relatively well-developed when born

References

Credo Reference. 2000. "Credo Reference" (On-line). II.G.11. Geese| Cambridge World History of Food. Accessed March 07, 2014 at http://search.credoreference.com/content/entry/cupfood/ii_g_11_geese/0.

Birdlife International. 2009. "Important Bird Areas Facts Sheet" (On-line). MN066| Mongol Daguur. Accessed April 03, 2014 at http://www.birdlife.org/datazone/sitefactsheet.php?id=16351.

Dog Breed Info Center. 2014. "Keeping Chinese Swan Geese as Pets" (On-line). Chinese Swan Goose. Accessed April 04, 2014 at http://www.dogbreedinfo.com/pets/goosechineseswan.htm.

Batbayar, N., J. Takekawa, S. Newman, D. Prosser, T. Natsagdorj, X. Xiao. 2011. Migration Strategies of Swan Geese Anser cygnoides from Northeast Mongolia. Wildfowl, 61: 90-109.

Benstead, P., J. Bird, S. Chan, M. Crosby, S. Mahood, N. Peet, J. Pilgrim, J. Taylor. 2008. "Species Fact Sheet" (On-line). Swan Goose Anser cygnoides. Accessed April 03, 2014 at http://www.birdlife.org/datazone/speciesfactsheet.php?id=373.

Fox, A., R. Hearn, L. Cao, P. Cong, X. Wang, Y. Zhang, S. Dou, X. Shao, M. Barter, E. Rees. 2008. Preliminary Observations of Diurnal Feeding Patterns of Swan Geese Anser cygnoides Using Two Different Habitats at Shengjin Lake, Anhui Province, China. Wildfowl, 58: 20-30.

Randler, C. 2007. Parental Investment in Swan Geese in an Urban Environment. The Wilson Journal of Ornithology, 119: 23-27.

Rohwer, F. 1988. Inter- and Intraspecific Relationships between Egg Size and Clutch Size in Waterfowl. The Auk, Vol. 105 No. 1: 161-176.

Tellkamp, M. 2004. Ducks, Geese, and Swans (Anatidae). Pp. 369-392 in M Hutchins, A Evans, J Jackson, D Kleiman, J Murphy, D Thoney, e al, eds. Grzimek's Animal Life Encyclopedia, Vol. 8, 2nd Edition. Detroit, MI: Gale.

Xu, Q., Y. Zhang, Y. Tong, G. Rong, Z. Huang, R. Zhao, W. Zhao, X. Wu, G. Chang, G. Chen. 2014. Identification and Differential Expression of MicroRNAs in Ovaries of Laying and Broody Geese (Anser cygnoides) by Solexa Sequencing. Plos One, 9/2: 1-9.

Zhang, Y., L. Cao, M. Barter, A. Fox, M. Zhao, F. Meng, H. Shi, Y. Jiang, W. Zhu. 2010. Changing Distribution and Abundance of Swan Goose Anser cygnoides in the Yangtze River Floodplain: the Likely Loss of a Very Important Wintering Site. Bird Conservation International, 10: 36-48.

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