The bar-headed goose (Anser indicus ) is a swan that breeds in Central Asia in thousands of colonies near mountain and winter lakes in South Asia, as far south as the Indian peninsula. It lays three to eight eggs at a time in the ground nest.
Video Bar-headed goose
Taxonomy
The gray goose genus Anser has no other members coming from Indian territory, or not at all in Ethiopia, Australia or Neotropic territory. Ludwig Reichenbach placed a cool-headed goose in the monotypic genus Eulabeia in 1852, although John Boyd's taxonomy treats both the Eulabeia and the genus Chen as subgenera. from anser .
Maps Bar-headed goose
Description
The bird is pale gray and easily distinguished from one of the other gray swans of the genus Anser by a black rod on his head. It is also more pale than other geese in this genus. In flight, his call is a common horned goose. The size of the goose is 71-76 cm long (28-30 inches) and weighs 1.87 to 2.3 kg (4.1-7.1 pounds).
Ecology
Summer habitat is a highland lake where the birds graze on the short grass. This species is reported to migrate south from Tibet, Kazakhstan, Mongolia and Russia before crossing the Himalayas. The bird has been the subject of medical science in recent years as an early victim of the H5N1 virus, HPAI (highly pathogenic avian influenza), in Qinghai. It suffers from the predation of crows, foxes, ravens, sea eagles, seagulls and others. However, the total population may increase, but it is very complex to assess population trends, as this species occurs over 2,500,000 km 2 (970,000 sq., Mi).
The bar-headed goose is one of the highest flying birds in the world, has been heard flying across Mt. Makalu - the fifth highest mountain on earth at 8,481 m (27,825 ft) - and apparently seen on Mt Everest - 8,848 m (29,029 ft) - though this is a secondhand report without verification. This demanding migration has long puzzled physiologists and naturalists: "there must be a good explanation of why birds fly to extreme heights... especially as there pass through the Himalayas at lower altitudes, and those used by other migratory bird species." In fact, headed deer has long been not directly traced (using GPS or satellite logging technology) flying higher than 6,540 meters (21,460 ft), and it is now believed that they took a high pass through the mountains.. The challenging northward migration from the Indian lowlands to the summer breeding in the Tibetan Plateau is done gradually, with flights across the Himalayas (from sea level) being carried out non-stop within just seven hours. Surprisingly, despite the predictable tail winds that blow up the Himalayas (in the same direction as the goose), the cool-headed goose throws this wind, waiting for them to die overnight, when they then do the greatest climbing level ever. recorded for birds, and kept this climb level for hours, according to research published in 2011.
The 2011 study found geese peaking at an altitude of about 6,400 m (21,000 ft). In a 2012 study that marked 91 swans and tracked their migration routes, it was determined that the swans spent 95% of their time under 5,784 m (18,976 ft), choosing to take longer routes through the Himalayas to take advantage of the lower. the valley and the operand. Only 10 marked swans were ever recorded above this height, and only one exceeded 6,500 m (21,300 feet), reaching 7,290 m (23,920 ft). All but one of these altitude flights recorded at night, which together with the morning, is the most common time for geese migration. The denser, colder air during this time may be equivalent to a height of hundreds of feet lower. It is thought by the authors of these two studies that the story of a swan flying at 8,000 m (26,000 ft) is an apocrypha. Male-headed goose has been observed flying at 23,000 feet.
Cold-headed goose migrate across the Himalayas to spend the winter in parts of South Asia (from Assam to the south like Tamil Nadu) The modern winter habitat of this species is a cultivated field, where it feeds on barley, rice and wheat, and can destroying plants The birds of Kyrgyzstan have been recorded for a stopover in western Tibet and southern Tajikistan for 20 to 30 days before migrating further south Some birds may show high winter fidelity.
They nest mainly in the Tibetan Plateau. The intrapecific parent parasitism is known to lower ranks trying to put their eggs in higher female nest ranks.
Goose-headed goose is often kept in captivity, as it is considered beautiful and easy to breed. Records in the United Kingdom are frequent, and almost certainly related to the escape. However, this species has been raised on several occasions in recent years, and about five pairs recorded in 2002, the most recent report available from the Rare Birds Breeding Panel. It is possible that, due to the combination of frequent migration, unintentional escape and intentional introduction, the species gradually became more established in Great Britain. The bird is friendly and does not cause problems for other birds. Wild populations are believed to be declining in the UK due to excessive hunting.
The cold-headed goose has either escaped or deliberately released to Florida, USA, but there is no evidence that the population is breeding and may only survive as the release or escape continues. [2]
Physiology and morphology
The main physiological challenge of cold-headed goose is extracting oxygen from the air of hypoxia and transporting it to aerobic muscle fibers to maintain flight at high altitudes. The flight is very expensive metabolically at high altitude because birds need to pack harder in thin air to generate lift. Research has found that cold-headed goose breathes deeper and more efficiently under low oxygen conditions, which serves to increase oxygen uptake from the environment. Hemoglobin from their blood has a higher affinity for oxygen than with low-altitude geese, which has been associated with a mutation of one amino acid. This mutation causes a conformational shift in the hemoglobin molecule from a low oxygen affinity form to a high oxygen affinity form. The left ventricle of the heart, which is responsible for pumping oxygenated blood to the body through the systemic circulation, has significantly more capillaries in cold-headed swans than the lowland birds, maintaining the oxygenation of heart muscle cells and thus cardiac output. Compared with lowland birds, mitochondria (the main site of oxygen consumption) in goose-headed goose muscle is significantly closer to the sarcolemma, reducing the distance of oxygen intracellular diffusion from capillary to mitochondria.
Goose-headed swans have slightly larger wingspanes for their weight than other geese, which are believed to help them fly at high altitudes. While this reduces the power output required for flight in thin air, birds at high altitudes still have to pack harder than lowland birds.
Cultural depictions
The cool-headed goose has been suggested as a model for Hamsa Indian mythology. Another interpretation suggests that the cool-headed goose may be Kadamb in ancient and medieval Sanskrit literature, while Hamsa generally refers to geese.
Gallery
See also
- Tsomoriri Wetlands Conservation Reserve
References
External links
- Bar-headed Goose is found in Brattleboro, Vermont, USA (April, 2009)
- Hawkes et al. (2011) Trans-Himalaya Flight from the cool-headed goose (Anser indicus)
Source of the article : Wikipedia
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