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. 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.
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
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|
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
Video Bar-headed Goose
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.