Bar-headed Goose (Anser indicus)

Bar-headed Goose

[order] ANSERIFORMES | [family] Anatidae | [latin] Anser indicus | [authority] Latham, 1790 | [UK] Bar-headed Goose | [FR] Oie a tete barree | [DE] Streifengans | [ES] Ansar Calvo | [NL] Indische Gans

Subspecies

Monotypic species

Genus

The waterfowl genus Anser includes all grey geese and sometimes the white geese. It belongs to the true geese and swan subfamily (Anserinae). The genus has a Holarctic distribution, with at least one species breeding in any open, wet habitats in the subarctic and cool temperate regions of the Northern Hemisphere in summer. Some also breed further south, reaching into warm temperate regions. They mostly migrate south in winter, typically to regions in the temperate zone. Numerous fossil species have been allocated to this genus. As the true geese are near-impossible to assign osteologically to genus, this must be viewed with caution. It can be assumed with limited certainty that European fossils from known inland sites belong into Anser. As species related to the Canada Goose have been described from the Late Miocene onwards in North America too, sometimes from the same localities as the presumed grey geese, it casts serious doubt on the correct generic assignment of the supposed North American fossil geese. The Early Pliocene Branta howardae is one of the cases where doubts have been expressed about its generic assignment.[citation needed] Similarly, Heterochen = Anser pratensis seems to differ profoundly from other species of Anser and might be placed into a different genus; alternatively, it might have been a unique example of a grey goose adapted for perching in trees.

Physical charateristics

The Bar-headed goose is the most striking of the grey geese. The name of this very gracefully built bird derives from the two prominent horse shoe shaped, brownish-black bars enhancing the white head.

The general colour is pale grey. A slightly greater wing area for its weight, compared with other geese, enables the Bar-headed to migrate at exceptionally high altitudes over the Himalayas.
Bar-headed geese have adapted to migrating over the Himalayas, the highest mountain range in the world. It has the ability to survive and fly at altitudes up to 30,000 feet. Most birds fly at altitudes between two and three thousand feet. Other mammals and birds would require extra oxygen just to survive at these altitudes. It is able to do this by regulating brain blood-flow at high altitudes. It needs the ability to fly at these heights so it can breed at lakes located at high elevations in Central Asia during the summer. It then flies back over the Himalayas to winter in India. It is known to fly over Mt. Everest because this is the shortest route to breeding grounds.

Listen to the sound of Bar-headed Goose

[audio:http://www.planetofbirds.com/MASTER/ANSERIFORMES/Anatidae/sounds/Bar-headed Goose.mp3]

Copyright remark: Most sounds derived from xeno-canto


wingspan min.: 142 cm wingspan max.: 168 cm
size min.: 72 cm size max.: 78 cm
incubation min.: 28 days incubation max.: 30 days
fledging min.: 48 days fledging max.: 30 days
broods: 1   eggs min.: 3  
      eggs max.: 6  

Range

Eurasia : Central

Habitat

The favoured summer habitats are the lakes at high altitudes where the short surrounding grass is appreciated. Most winter grazing areas are currently under cultivation and the Bar-headed has become reliant on wheat, barley and rice crops resulting in considerable damage to the shoots of these crops.

Reproduction

These geese nest around lakes in the open, usually a shallow depression in very dense colonies at altitudes up to 16,000 feet. Four to eight eggs are laid in a shallow depression and incubated for 28 to 30 days. The highly gregarious geese remain in the breeding grounds from late March to mid April and will leave the nesting area in late August through September.
Both parents care for the goslings which are grayish-brown and yellow. The young fledge at about 50 days of age. Parents will often double-clutch if the first eggs are removed. Some may breed at two years of age, but as with many members of the Anser genus, three years of age is most common. Immature geese are somewhat paler and lack the bars on the head

Feeding habits

Vegetarian. Grasses and agricultural crops are foraged mainly by grazing.

Video Bar-headed Goose

httpv://www.youtube.com/watch?v=wm_2cmsFh30

copyright: youtube


Conservation

This species has an extremely large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). Despite the fact that the population trend appears to be decreasing, the decline is not believed to be sufficiently rapid to approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.
Het eerste broedgeval van de Indische gans in Nederland werd gerapporteerd in 1977. Het zou nog tot 1986 duren voordat een tweede broedgeval volgde. Vanaf dat jaar volgen de broedgevallen elkaar in rap temp op en nemen de aantallen sterk toe, doordat ook de jongen mee gaan doen aan de reproductie van de populatie. Inmiddels zijn de aantallen toegenomen tot ongeveer 70 tot honderd broedparen die zich in het wild kunnen handhaven. De toename verloopt snel, met ongeveer 10% per jaar.
Bar-headed Goose status Least Concern

Migration

Majority of birds migratory, flying southwards to winter in northern India and adjacent countries.

Distribution map

Bar-headed Goose distribution range map

Literature

Title Heart rate and the rate of oxygen consumption of flying and walking barnacle geese (Branta leucopsis) and bar-headed geese (Anser indicus)
Author(s): S. Ward1 C. M. Bishop, A. J. Woakes and P. J. Butler
Abstract: We tested the hypotheses that the relationship bet..[more]..
Source: The Journal of Experimental Biology 205, 3347-3356 (2002) V .

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