Anser indicus

Geographic Range

Bar-headed geese ( Anser indicus ) have a breeding range that stretches from Mongolia south through Russia and Western China to Tibet and as far west as Kyrgyzstan. Approximately 25% of the global population of bar-headed geese winter on the southern Tibetan-Qinghai Plateau. Another wintering area for a portion of the population is India and Bangladesh.

• Biogeographic Regions
• palearctic palearctic
  • native native
• oriental oriental
  • native native

Habitat

Bar-headed geese can be found at high elevations. They use habitats like mountain grasslands and crop fields from surrounding villages. Bar-headed geese tend to use freshwater marshes, lakes, and streams that are around elevations of 4,000 to 6,000 meters above sea level as stop-over and over-wintering sites. Some geese have even been reported to migrate at altitudes of 9,000 meters when they cross the Himalaya Mountains.

• Habitat Regions
• temperate temperate
• terrestrial terrestrial
• freshwater freshwater

• Terrestrial Biomes
• savanna or grassland savanna or grassland

• Aquatic Biomes
• lakes and ponds
• rivers and streams
• brackish water brackish water

• Wetlands
• marsh marsh

• Other Habitat Features
• agricultural agricultural

Physical Description

Bar-headed geese have grey bodies, with orange legs and a black and white neck. This species is named for the obvious black U-shaped bars on the back of the white head. They weigh between 2 and 3 kg (4.5 and 6.5 lbs) with a wingspan between 140 and 160 cm (55 and 62 inch), and are between 68 and 78 cm (27 and 30 inch) in length. Bar-headed geese have a basal metabolic rate of 756 cubic centimeters of oxygen per hour.

• Other Physical Features
• endothermic endothermic
• homoiothermic
• bilateral symmetry bilateral symmetry

• Sexual Dimorphism
• sexes alike

Reproduction

Bar-headed geese are seasonal breeders. They exhibit a monogamous mating system, where males pair with one single female for several years. During times when the population is biased towards females a polygynous system is adopted where a monogamous pair may be joined by multiple secondary females. These secondary females also breed with the male of the pair. Because they breed in large colonies, females defend their nests from socially lower females that may be using brood parasitism to increase the likely hood of their offspring's survival.

• Mating System
• monogamous monogamous
• polygynous polygynous

Bar-headed geese typically breed on an annual basis. This occurs during the spring. Nesting occurs from the last week of April until June. They typically lay 3 to 8 eggs on average. After 28 to 30 days the goslings hatch. There was little information on the birth mass of the goslings. They then fledge by 55 to 60 days, and reach sexual maturity at 3 years of age. Bar-headed geese tend to breed on the Tibetan-Qinghai Plateau. They lay their eggs in ground nests at high elevations in the highland marshes and lakes.

• Key Reproductive Features
• iteroparous iteroparous
• seasonal breeding seasonal breeding
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual sexual
• fertilization fertilization
• oviparous oviparous

Bar-headed geese use biparental care when raising young. Studies show that male bar-headed geese are more alert and defensive when in the presence of their goslings. These same studies show that the goslings have the added benefit of an increased survival rate from having both parents. Both parents provide their goslings with protection from predators and other geese. In addition to that the parents also protect the goslings' food.

• Parental Investment
• precocial precocial
• male parental care male parental care
• female parental care female parental care

Lifespan/Longevity

Little information is published on the lifespan of bar-headed geese. Like most geese they are long-lived. A close relative, greylag geese , have a lifespan of 20 years in the wild and the oldest one in captivity lived 31 years.

Behavior

This species is typical to most in the order Anseriformes in that they are a social species migrating in family groups or large colonies. They are very motile migrating twice a year over the Himalaya Mountains to and from their breeding grounds on the Tibetan-Qinghai Plateau. They migrate in "V"-formations or variations of it. They have a social hierarchy consisting of mated male-female pairs being the highest, followed by secondary females that are usually part of a harem, and lowest socially is lone females. This harem usually forms when the population is biased towards females. Bar-headed geese make ground nests with shallow depressions at high elevations. They defend these nests from predators and from other socially lower females.

• Key Behaviors
• flies
• motile motile
• migratory migratory
• territorial territorial
• colonial colonial
• dominance hierarchies dominance hierarchies

Home Range

Their Breeding range is in Western China, Mongolia, and on the Tibetan-Qinghai Plateau. Their non-breeding range is in India, Bangladesh and Nepal.

Communication and Perception

Like most geese, bar-headed geese fly in "V"-shaped formations. When the lead bird gets tired they fall to the back of the formation and another goose takes the lead. The formation can vary from a traditional V to other shapes like "J"-shape and the echeleon shape where one arm of the "V"-shape is missing. The benefit of this style of flight is that each individual flies with reduced drag, which in turn saves them energy. They use vocal communications and visual cues to maintain their spacing while flying in these formations. This also assists them in staying in closely related family groups as they move from traditional feeding and breeding areas. Like other waterfowl they can also see in the ultraviolet spectrum of light.

• Communication Channels
• visual visual
• tactile tactile
• acoustic acoustic

• Perception Channels
• visual visual
• ultraviolet
• tactile tactile
• acoustic acoustic
• chemical chemical
• magnetic magnetic

Food Habits

Bar-headed geese generally feed on the highland grasses surrounding their lakes and streams where they nest. During other times of the year they can be found eating on agricultural crops such as corn, wheat, barley, and rice.

• Primary Diet
• herbivore herbivore
  • folivore folivore
  • granivore granivore

• Animal Foods
• fish
• insects

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

Predation

From the air the bar-headed geese are prey for sea eagles , golden eagles , crows , and ravens . On the ground the geese are preyed upon by red foxes . Some of the adaptations the geese have developed is the ability to survive at high altitudes. This limits the amount of ground predators that can reach them. They can survive at high altitudes because they have a higher density of capillaries that are spaced closer together this allows them to deliver more oxygen to their muscles, in particular their flight muscles. In addition to their capillaries they also have hemoglobin in their blood that is more efficient at taking in oxygen. Another adaptation is that these geese tend to live in large colonies or smaller family groups which enhances predator detection.

Ecosystem Roles

These geese are prey for animals such as red foxes , and golden eagles . Some can also be parasites by using higher ranked females as hosts to raise their offspring. In addition they are also carriers of the H5N1 virus and capable of passing the virus to humans, and other animals as well. They assist in the dispersal of grass seeds they eat throughout the year.

• Ecosystem Impact
• disperses seeds

Economic Importance for Humans: Positive

These geese benefit humans because of ecotourism to the wildlife areas that they use as refueling stops during their migrations. "The East Calcutta Wetlands in Western Bengal (a stop over site for migrating Bar-headed Geese) has environmental benefits worth 38.54 million dollars"(Bhattacharyya et al., 2008).

• Positive Impacts
• ecotourism ecotourism

Economic Importance for Humans: Negative

Bar-headed geese were one of the first species to show signs of the H5N1 (Bird Flu) virus. In addition to carrying the virus the geese are also pests to the local villagers. Since they feed on the wheat, rice, and other crops around their roosting areas, they can cause damage to farm fields.

• Negative Impacts
• injures humans
  • carries human disease
• crop pest

Conservation Status

Bar-headed geese are listed on the IUCN Red List as Least Concerned. They have no special status under the US Migratory Bird Act or on the US Federal List because there is no population living in the US. Nor are they protected under the US Endangered Species Act. CITES contains no special status for the species either.

Additional Links

Encyclopedia of Life

Contributors

Dominick Cucinello (author), University of Wisconsin-Stevens Point, Christopher Yahnke (editor), University of Wisconsin-Stevens Point, Laura Podzikowski (editor), Special Projects.

References

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