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.
- Biogeographic Regions
- palearctic
- Other Geographic Terms
- holarctic
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.
- Habitat Regions
- temperate
- terrestrial
- saltwater or marine
- freshwater
- Terrestrial Biomes
- savanna or grassland
- Aquatic Biomes
- pelagic
- lakes and ponds
- rivers and streams
- coastal
- brackish water
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.
- Other Physical Features
- endothermic
- homoiothermic
- bilateral symmetry
- Sexual Dimorphism
- sexes alike
- ornamentation
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.
- Mating System
- monogamous
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.
- Key Reproductive Features
- iteroparous
- seasonal breeding
- gonochoric/gonochoristic/dioecious (sexes separate)
- sexual
- oviparous
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.
- Parental Investment
- precocial
- male parental care
- female parental care
-
pre-hatching/birth
-
provisioning
- female
-
protecting
- male
-
provisioning
-
pre-weaning/fledging
-
provisioning
- female
-
protecting
- male
- female
-
provisioning
-
pre-independence
-
protecting
- male
- female
-
protecting
- 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.
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.
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.
- Key Behaviors
- terricolous
- flies
- glides
- natatorial
- crepuscular
- motile
- migratory
- social
- colonial
- dominance hierarchies
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.
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.
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.
- Plant Foods
- leaves
- roots and tubers
- seeds, grains, and nuts
- Foraging Behavior
- stores or caches food
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.
- Anti-predator Adaptations
- cryptic
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.
- Ecosystem Impact
- creates habitat
- soil aeration
- Swan geese have no known host species.
- Swan geese are not known to be mutualistic with any other 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.
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.
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.
- 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.
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.
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.
Additional Links
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.
- Palearctic
-
living in the northern part of the Old World. In otherwords, Europe and Asia and northern Africa.
- introduced
-
referring to animal species that have been transported to and established populations in regions outside of their natural range, usually through human action.
- native range
-
the area in which the animal is naturally found, the region in which it is endemic.
- holarctic
-
a distribution that more or less circles the Arctic, so occurring in both the Nearctic and Palearctic biogeographic regions.
Found in northern North America and northern Europe or Asia.
- 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.
- saltwater or marine
-
mainly lives in oceans, seas, or other bodies of salt water.
- freshwater
-
mainly lives in water that is not salty.
- 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.
- pelagic
-
An aquatic biome consisting of the open ocean, far from land, does not include sea bottom (benthic zone).
- coastal
-
the nearshore aquatic habitats near a coast, or shoreline.
- brackish water
-
areas with salty water, usually in coastal marshes and estuaries.
- marsh
-
marshes are wetland areas often dominated by grasses and reeds.
- swamp
-
a wetland area that may be permanently or intermittently covered in water, often dominated by woody vegetation.
- 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.
- urban
-
living in cities and large towns, landscapes dominated by human structures and activity.
- suburban
-
living in residential areas on the outskirts of large cities or towns.
- riparian
-
Referring to something living or located adjacent to a waterbody (usually, but not always, a river or stream).
- estuarine
-
an area where a freshwater river meets the ocean and tidal influences result in fluctuations in salinity.
- 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.
- 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.
- 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.
- monogamous
-
Having one mate at a time.
- 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).
- 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
- oviparous
-
reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.
- young precocial
-
young are relatively well-developed when born
- male parental care
-
parental care is carried out by males
- female parental care
-
parental care is carried out by females
- natatorial
-
specialized for swimming
- crepuscular
-
active at dawn and dusk
- motile
-
having the capacity to move from one place to another.
- migratory
-
makes seasonal movements between breeding and wintering grounds
- social
-
associates with others of its species; forms social groups.
- 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.
- dominance hierarchies
-
ranking system or pecking order among members of a long-term social group, where dominance status affects access to resources or mates
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- 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
- choruses
-
to jointly display, usually with sounds, at the same time as two or more other individuals of the same or different species
- stores or caches food
-
places a food item in a special place to be eaten later. Also called "hoarding"
- 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.
- soil aeration
-
digs and breaks up soil so air and water can get in
- pet trade
-
the business of buying and selling animals for people to keep in their homes as pets.
- food
-
A substance that provides both nutrients and energy to a living thing.
- herbivore
-
An animal that eats mainly plants or parts of plants.
- folivore
-
an animal that mainly eats leaves.
- granivore
-
an animal that mainly eats seeds
- visual
-
uses sight to communicate
- tactile
-
uses touch to communicate
- acoustic
-
uses sound to communicate
- chemical
-
uses smells or other chemicals to communicate
References
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 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.
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 .