Bar-headed goose | |
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Scientific classification ![]() | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Aves |
Order: | Anseriformes |
Family: | Anatidae |
Genus: | Anser |
Species: | A. indicus |
Binomial name | |
Anser indicus (Latham, 1790) | |
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Synonyms | |
Anser indica( lapsus ) Contents |
The bar-headed goose (Anser indicus) is a goose that breeds in Central Asia in colonies of thousands near mountain lakes and winters in South Asia, as far south as peninsular India. It lays three to eight eggs at a time in a ground nest. It is known for the extreme altitudes it reaches when migrating across the Himalayas.
The grey goose genus Anser has no other member indigenous to the Indian region, nor any at all to the Ethiopian, Australian, or Neotropical regions. Ludwig Reichenbach placed the bar-headed goose in the monotypic genus Eulabeia in 1852, [2] though John Boyd's taxonomy treats both Eulabeia and the genus Chen as subgenera of Anser. [3]
The bird is pale grey and is easily distinguished from any of the other grey geese of the genus Anser by the black bars on its head. It is also much paler than the other geese in this genus. In flight, its call is a typical goose honking. A mid-sized goose, it measures 71–76 cm (28–30 in) in total length and weighs 1.87–3.2 kg (4.1–7.1 lb).
The summer habitat is high-altitude lakes where the bird grazes on short grass. The species has been reported as migrating south from Tibet, Kazakhstan, Mongolia and Russia before crossing the Himalayas. The bird has come to the attention of medical science in recent years as having been an early victim of the H5N1 virus, HPAI (highly pathogenic avian influenza), at Qinghai. It suffers predation from crows, foxes, ravens, sea eagles, gulls and others. The total population may, however, be increasing, but it is complex to assess population trends, as this species occurs over more than 2,500,000 km2 (970,000 sq mi). [1]
The bar-headed goose is one of the world's highest-flying birds, [4] having been heard flying across Mount Makalu – the fifth highest mountain on earth at 8,481 m (27,825 ft) – and apparently seen over Mount Everest –8,848 m (29,029 ft) – although this is a second-hand report with no verification. [5] This demanding migration has long puzzled physiologists and naturalists: "there must be a good explanation for why the birds fly to the extreme altitudes... particularly since there are passes through the Himalaya at lower altitudes, and which are used by other migrating bird species." [6] In fact, bar-headed geese had for a long time not been directly tracked (using GPS or satellite logging technology) flying higher than 6,540 metres (21,460 ft), and it is now believed that they do take the high passes through the mountains. The challenging northward migration from lowland India to breed in the summer on the Tibetan Plateau is undertaken in stages, with the flight across the Himalaya (from sea-level) being undertaken non-stop in as little as seven hours. Surprisingly, despite predictable tail winds that blow up the Himalayas (in the same direction of travel as the geese), bar-headed geese spurn these winds, waiting for them to die down overnight, when they then undertake the greatest rates of climbing flight ever recorded for a bird, and sustain these climbs rates for hours on end, according to research published in 2011. [7]
The 2011 study found the geese peaking at an altitude of around 6,400 m (21,000 ft). [4] In a 2012 study that tagged 91 geese and tracked their migration routes, it was determined that the geese spent 95% of their time below 5,784 m (18,976 ft), choosing to take a longer route through the Himalayas in order to utilize lower-altitude valleys and passes. Only 10 of the tagged geese were ever recorded above this altitude, and only one exceeded 6,500 m (21,300 ft), reaching 7,290 m (23,920 ft). All but one of these high-altitude flights were recorded at night, which along with the early morning, is the most common time of day for geese migration. The colder denser air during these times may be equivalent to an altitude hundreds of meters lower. It is suspected by the authors of these two studies that tales of the geese flying at 8,000 m (26,000 ft) are apocryphal. [8] Bar headed geese have been observed flying at 7,000 metres (23,000 ft). [9]
The bar-headed goose migrates over the Himalayas to spend the winter in parts of South Asia (from Assam to as far south as Tamil Nadu. [10] The modern winter habitat of the species is cultivated fields, where it feeds on barley, rice and wheat, and may damage crops. Birds from Kyrgyzstan have been seen to stopover in western Tibet and southern Tajikistan for 20 to 30 days before migrating farther south. Some birds may show high wintering site fidelity. [11]
They nest mainly on the Tibetan Plateau. Intraspecific brood parasitism is noticed with lower rank females attempting to lay their eggs in the nests of higher ranking females. [12]
The bar-headed goose is often kept in captivity, as it is considered beautiful and breeds readily. Recorded sightings in Great Britain are frequent, and almost certainly relate to escapes. However, the species has bred on several occasions in recent years, and around five pairs were recorded in 2002, the most recent available report of the Rare Birds Breeding Panel. It is possible that, owing to a combination of frequent migration, accidental escapes and deliberate introduction, the species is becoming gradually more established in Great Britain.
The bar-headed goose has escaped or been deliberately released in Florida, U.S., but there is no evidence that the population is breeding and it may only persist due to continuing escapes or releases.
The main physiological challenge of bar-headed geese is extracting oxygen from hypoxic air and transporting it to aerobic muscle fibres in order to sustain flight at high altitudes. Flight is very metabolically costly at high-altitudes because birds need to flap harder in thin air to generate lift. [13] Studies have found that bar-headed geese breathe more deeply and efficiently under low-oxygen conditions, which serves to increase oxygen uptake from the environment. [14] The haemoglobin of their blood has a higher affinity for oxygen than that of low-altitude geese, [15] which has been attributed to a single amino acid point mutation. [16] This mutation causes a conformational shift in the haemoglobin molecule from the low-oxygen to the high-oxygen affinity form. [17] The left-ventricle of the heart, which is responsible for pumping oxygenated blood to the body via systemic circulation, has significantly more capillaries in bar-headed geese than in lowland birds, maintaining oxygenation of cardiac muscle cells and thereby cardiac output. [18] Compared to lowland birds, mitochondria (the main site of oxygen consumption) in the flight muscle of bar-headed geese are significantly closer to the sarcolemma, [19] decreasing the intracellular diffusion distance of oxygen from the capillaries to the mitochondria.
Bar-headed geese have a slightly larger wing area for their weight than other geese, which is believed to help them fly at high altitudes. [20] While this decreases the power output required for flight in thin air, birds at high altitude still need to flap harder than lowland birds. [21]
The bar-headed goose has been suggested as being the model for the Hamsa of Indian mythology. [22] Another interpretation suggests that the bar-headed goose is likely to be the Kadamb in ancient and medieval Sanskrit literature, whereas Hamsa generally refers to the swan. [23]
A goose is a bird of any of several waterfowl species in the family Anatidae. This group comprises the genera Anser and Branta. Some members of the Tadorninae subfamily are commonly called geese, but are not considered "True Geese" taxonomically. More distantly related members of the family Anatidae are swans, most of which are larger than true geese, and ducks, which are smaller.
The greylag goose or graylag goose is a species of large goose in the waterfowl family Anatidae and the type species of the genus Anser. It has mottled and barred grey and white plumage and an orange beak and pink legs. A large bird, it measures between 74 and 91 centimetres in length, with an average weight of 3.3 kilograms. Its distribution is widespread, with birds from the north of its range in Europe and Asia often migrating southwards to spend the winter in warmer places, although many populations are resident, even in the north. It is the ancestor of most breeds of domestic goose, having been domesticated at least as early as 1360 BCE. The genus name and specific epithet are from anser, the Latin for "goose".
The greater white-fronted goose is a species of goose that is closely related to the smaller lesser white-fronted goose. The greater white-fronted goose is migratory, breeding in northern Canada, Alaska, Greenland and Russia, and winters farther south in North America, Europe and Asia. It is named for the patch of white feathers bordering the base of its bill: albifrons comes from the Latin albus "white" and frons "forehead". In the United Kingdom and Ireland, it has been known as the white-fronted goose; in North America it is known as the greater white-fronted goose, and this name is also increasingly adopted internationally. Even more distinctive are the salt-and-pepper markings on the breast of adult birds, which is why the goose is colloquially called the "specklebelly" in North America.
The taiga bean goose is a goose that breeds in northern Europe and Asia. It is migratory and winters further south in Europe and Asia. This and the tundra bean goose are recognised as separate species by the American Ornithological Society and the International Ornithologists' Union, but are considered a single species by other authorities. The taiga and tundra bean goose diverged about 2.5 million years ago and established secondary contact c. 60,000 years ago, resulting in extensive gene flow.
The pink-footed goose is a goose which breeds in eastern Greenland, Iceland, Svalbard, and recently Novaya Zemlya. It is migratory, wintering in northwest Europe, especially Ireland, Great Britain, the Netherlands, and western Denmark. The name is often abbreviated in colloquial usage to "pinkfoot". Anser is the Latin for "goose", and brachyrhynchus comes from the ancient Greek brachus "short" and rhunchos "bill".
The lesser white-fronted goose is a goose closely related to the larger greater white-fronted goose. It breeds in the northernmost Palearctic, but it is a scarce breeder in Europe, with a reintroduction attempt in Fennoscandia.
The snow goose is a species of goose native to North America. Both white and dark morphs exist, the latter often known as blue goose. Its name derives from the typically white plumage. The species was previously placed in the genus Chen, but is now typically included in the "gray goose" genus Anser.
Bird migration is the regular seasonal movement, often north and south, between breeding and wintering grounds. Many species of bird migrate, typically by flying. Migration carries high costs in predation and mortality, and is driven primarily by the availability of food. It occurs mainly in the Northern Hemisphere.
The Canada goose, sometimes called Canadian goose, is a large wild goose with a black head and neck, white cheeks, white under its chin, and a brown body. It is native to the arctic and temperate regions of North America, and it is occasionally found during migration across the Atlantic in northern Europe. It has been introduced to France, the United Kingdom, Ireland, Finland, Sweden, Denmark, New Zealand, Japan, Chile, Argentina, and the Falkland Islands. Like most geese, the Canada goose is primarily herbivorous and normally migratory; often found on or close to fresh water, the Canada goose is also common in brackish marshes, estuaries, and lagoons.
The Andean goose is a species of waterfowl in tribe Tadornini of subfamily Anserinae. It is found in Argentina, Bolivia, Chile, and Peru.
The swan goose is a large goose with a natural breeding range in inland Mongolia, Northeast China, and the Russian Far East. It is migratory and winters mainly in central and eastern China. Vagrant birds are encountered in Japan and Korea, and more rarely in Kazakhstan, Laos, coastal Siberia, Taiwan, Thailand and Uzbekistan.
The cotton pygmy goose or cotton teal is a small perching duck which breeds in Asia, Southeast Asia extending south and east to Queensland where they are sometimes called white-quilled pygmy goose. They are among the smallest waterfowl in the world and are found in small to large waterbodies with good aquatic vegetation. They are usually seen in pairs or larger groups of pairs, roosting and nesting on trees near water. They are strong fliers and are known to disperse widely, especially in winter. Their breeding season coincides with the rains.
The haṃsa is an aquatic migratory bird, referred to in ancient Sanskrit texts which various scholars have interpreted as being based on the goose, the swan, or even the flamingo. Its image is used in Indian and Southeast Asian culture as a spiritual symbol and a decorative element. It is also used in a metaphorical sense with the bird attributed with the mythical ability to extract milk from a mixture of milk and water or good from evil. In Hindu iconography, hamsa is the vahana of Brahma, Gayatri, Saraswati, and Vishvakarma.
Anser is a waterfowl genus that includes the grey geese and the white geese. It belongs to the true goose and swan subfamily of Anserinae under the family of Anatidae. 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 farther south, reaching into warm temperate regions. They mostly migrate south in winter, typically to regions in the temperate zone between the January 0 °C (32 °F) and 5 °C (41 °F) isotherms.
Pallas's fish eagle, also known as Pallas's sea eagle or band-tailed fish eagle, is a large, brownish sea eagle. It breeds in the east Palearctic in Kazakhstan, Russia, Tajikistan, Turkmenistan, Uzbekistan, Mongolia, China, India, Nepal, Bangladesh, Myanmar and Bhutan. It is listed as Endangered on the IUCN Red List. It is partially migratory, with Central Asian birds wintering among the southern Asian birds in northern India, and also further west to the Persian Gulf.
Chronic mountain sickness (CMS) is a disease in which the proportion of blood volume that is occupied by red blood cells increases (polycythaemia) and there is an abnormally low level of oxygen in the blood (hypoxemia). CMS typically develops after extended time living at high altitude. It is most common amongst native populations of high altitude nations. The most frequent symptoms of CMS are headache, dizziness, tinnitus, breathlessness, palpitations, sleep disturbance, fatigue, loss of appetite, confusion, cyanosis, and dilation of veins.
Whiffling is a term used in ornithology to describe the behavior whereby a bird rapidly descends with a zig-zagging, side-slipping motion. Sometimes to whiffle, a bird flies briefly with its body turned upside down but with its neck and head twisted 180 degrees around in a normal position. The aerodynamics which usually give a bird lift during flying are thereby inverted and the bird briefly plummets toward the ground before this is quickly reversed and the bird adopts a normal flying orientation. This erratic motion resembles a falling leaf, and is used to avoid avian predators or may be used by geese to avoid a long, slow descent over an area where wildfowling is practised.
Organisms can live at high altitude, either on land, in water, or while flying. Decreased oxygen availability and decreased temperature make life at such altitudes challenging, though many species have been successfully adapted via considerable physiological changes. As opposed to short-term acclimatisation, high-altitude adaptation means irreversible, evolved physiological responses to high-altitude environments, associated with heritable behavioural and genetic changes. Among vertebrates, only few mammals and certain birds are known to have completely adapted to high-altitude environments.
Vadayil Sankaran Vijayan is an Indian environmentalist, wildlife biologist, ornithologist, an admirer of naturopathy and the founding Director of the Salim Ali Centre for Ornithology and Natural History. He is currently the chairman of the Salim Ali Foundation.
The bean goose is a goose that breeds in northern Europe and Eurosiberia. It has two distinct varieties, one inhabiting taiga habitats and one inhabiting tundra. These are recognised as separate species by the American Ornithologists' Union and the IOC, but are considered a single species by other authorities, such as the British Ornithologists' Union. It is migratory and winters further south in Europe and Asia.