Birds that fly on great heights
Ruppell’s griffon vulture (Gyps rueppellii)
Weighing about 8 kg Ruppell’s griffon vultures belong chiefly to the drier parts of Africa. They are the highest-flying birds in the world. In one recorded instance a bird collided with an aircraft at an altitude of 37,000 ft (11,277 m) over Abidjan, Ivory Coast, western Africa. The incident took place on November 29, 1973. Fortunately, there was no loss of life and the plane landed safely with one damaged engine.
Why these birds select such a high altitude as a flight path? The reason suggested is that thinner air allows faster flight without much effort and saves precious energy. Flying at such a great height, vultures face almost no physiological problems with regard to breathing; they have much more efficient breathing system than other living beings, including humans.
Their flow of blood enables oxygen to be extracted from air, with far greater efficiency than any other living being. If the flight is in cloudless condition, low temperature at great heights too does not bother them.
In Africa Ruppell’s griffons are found from Eritrea and Sudan, south to Tanganyika and west to Guinea in deserts and open plains, and also frequently in mountainous districts. They feed exclusively on carrion.
Common Crane (Grus grus)
The common crane, also known as the Eurasian crane, has been recorded flying across the Himalayas at heights up to 33,000 feet (10,058 m). This allows them to avoid eagles and other predatory birds waiting for the ambush in the mountain passes.
The species is a long distance migrant and winters predominantly in northern Africa. Usually flying in “V” formations, some flocks winter in southern Europe, including Portugal, Spain and France. Most eastern common cranes winter in the river valleys of Sudan, Ethiopia, Tunisia and Eritrea with smaller numbers in Turkey, northern Israel, Iraq and parts of Iran. The third major wintering region is in the northern half of Indian subcontinent, including Pakistan. Minimal wintering also occurs in Burma, Vietnam and Thailand. Lastly, they also winter in eastern China, where they are often the most common crane (outnumbering black-necked cranes ten-to-one). They are rare visitors to Japan and Korea, mostly blown over from the Chinese wintering population. The species is a rare vagrant to western North America, where they are occasionally seen with flocks of migrating sandhill cranes (Grus canadensis).
This large, stately bird is a medium-sized crane. It is the only crane species commonly found in Europe besides the demoiselle crane (Anthropoides virgo). Common cranes are 100–130 cm (39–51 in) high with a 180–240 cm (71–94 in) wingspan. The body weight can range from 3 to 6.1 kg (6.6 to 13.4 lb).
The species is slate-grey overall. Found in the northern parts of Europe and Asia, bird’s forehead and lores are blackish with a bare red crown and a white streak extending from behind the eyes to the upper back. They have loud, piercing trumpeting call that can be heard from a considerable distance.
Bar-headed goose (Anser indicus)
There are claims that Bar-headed geese have been seen flying over the world’s highest mountain range, the Himalayas, at altitudes of 29,500 ft (8,991 m) and across Mount Makalu, the fifth highest peak, at 27,825 ft (8,481 m). The summit of Mount Everest is 29028.87 ft (8,848 m).
Researches done on the subject in recent years raise questions on these claims. According to a research published in 2011, the demanding northward migration from the lowlands of India to breed on the Tibetan Plateau in summer is undertaken in stages. Flight across the Himalayas is undertaken non-stop in as little as seven hours. Amazingly, despite predictable tail winds that blow up the Himalayas (in the same direction of travel as the geese), the birds spurn these winds, waiting for them to die down overnight, when they undertake the greatest rates of climbing flight ever recorded for a bird, and sustain it for hours on. The study found them peaking at an altitude of around 6,400 m (21,000 ft).
In another study conducted in 2012, ninety-one geese were tagged and tracked during their migration. It was found that they spent 95 per cent of their time below 5,784 meters (18,976 ft), choosing to take a longer route through the Himalayas in order to utilize lower-altitude valleys and passes. Only 10 birds were recorded above this altitude out of which only one exceeded 6,500 m (21,300 ft), reaching 6,540 m (21,460 ft) on an overnight flight, when the air was cool (and therefore dense). While it cannot be ruled out that they do sometimes reach higher altitudes, authors of the two studies believe the claim of geese touching 8,000 m (26,000 ft) is too farfetched.
The main physiological challenge for these birds is extracting oxygen from oxygen-deficient air and sending it to aerobic muscles in order to keep up flight at higher altitudes. At such a height, where air is very thin, flight is very costly metabolically as the birds need to flap harder to generate lift. To overcome this problem geese breathe more efficiently and deeply under low oxygen conditions, which serves to increase oxygen uptake from the environment. Another specialization is the hemoglobin in their blood that has a higher affinity for oxygen compared to low-altitude geese. This is due to a single amino acid point mutation, which causes a conformational shift in the hemoglobin molecule from the low oxygen affinity form to the high oxygen affinity form. In addition to this, left-ventricle of their heart, responsible for pumping oxygenated blood to the body via systemic circulation, has more capillaries compared to lowland birds. This maintains oxygenation of cardiac muscle cells and thereby cardiac output. In comparison to lowland birds, mitochondria (main site of oxygen consumption) in their flight muscles are very close to the sarcolemma, which decreases the intracellular diffusion distance of oxygen from the capillaries to mitochondria.
In comparison to other geese, they have a little larger wing area for their body weight, which is believed to aid them fly at high altitudes. While this decreases the power output required for flight in thin air, bar-headed geese still need to flap harder than lowland birds at high-altitude.
Two black bars on head are distinguishing features
Anser indicus are pale grey in colour and can be easily distinguished from other grey geese of the same genus by the two black bars on their heads. Weighing 1.90–3.2 kg, they make typical goose honking while flying. They migrate over the Himalayas to spend winters in parts of South Asia (in India from Assam to as far south as Tamil Nadu). Cultivated fields are their winter habitats, where they feed on barley, rice and wheat, and may also damage crops. Birds from Kyrgyzstan have been observed stopping over in western Tibet and southern Tajikistan for a fortnight to a month’s time before flying further south. Some flocks may show high wintering site fidelity.
They breed near mountain lakes in Central Asia in colonies of thousands. Birds suffer predation usually from foxes, gulls, sea eagles, crows and ravens. The species occurs over more than 2,500,000 sq. km (970,000 sq mi) of area.
One of the largest man-made wetlands, spread over 307-square km, in the foothills of Himalayas, the Pong Dam reservoir in Himachal Pradesh, has become home to around 43,000 bar-headed geese, probably half their numbers globally, claim wildlife officials. They said it was the largest influx of any winter migrant in the Pong wetlands.
“Around 43,000 migratory bar-headed geese were recorded during the two-day census of waterfowl species, conducted by the state wildlife department from 29 January 2014 at the Pong reservoir,” assistant conservator of forests (wildlife) D S Dadwal said.
Records of the state wildlife department say the largest influx of the bar-headed geese so far recorded in Pong Dam was 40,000 birds in 2010. Barring 2001, when only 5,500 birds were spotted, numbers have ranged between 28,000 and 23,000 in the past few years. In 2013 the number of geese was 34,000 birds in the dam.
Bombay Natural History Society assistant director S Balachandran, who has tracked migratory routes of the geese and some duck species through satellite and leg-rings in Pong Dam reservoir in Himachal Pradesh (India), says the global number of bar-headed geese is believed to be around 100,000. About half of them winter in India.
Whooper swan (Cygnus cygnus)
It is another high-flying bird. On 9th December 1967 a group of swans, probably whoopers, were seen by the pilot of a civilian transport aircraft over the Inner Hebrides, an archipelago off the west coast of mainland Scotland, at an altitude of about 27,000 ft. (8,229m). Not only the height was breath taking, the speed was also astonishing with 139 km/hour or 86 mph (ground speed) and the temperature was lower than 48 degrees C below zero.
Whooper swans breed in Scandinavia and northern Russia, but with the onset of winters they migrate to the Atlantic seaboard of Western Europe. While flying they make loud bugle-sounding calls that are, probably, the farthest-audible calls of any bird species. Such calls keep the family flocks together on long journeys.
Like all swans they too have difficulty in taking off, but once airborne their heavy body helps in pushing through strong and adverse winds. While on long migratory flights they fly in V-formation, which creates slipstream effect (the stream of air driven back by an aircraft propeller or the stream of air behind any moving vehicles or other object), which helps in saving precious energy while cruising on high winds at great altitude.
Alpine chough (Pyrrhocorax graculus)
Also known as Yellow-billed chough it is not only high flying black bird, but also lives almost permanently at great heights ranging from 11,500 to 16,400 ft (3505.2 m to 4998.7 m) in the Himalayas. In extreme cases it has been found nesting at 21,300 ft (6492.2 m), higher than any other bird, even surpassing the Red-billed chough (Pyrrhocorax pyrrhocorax) which has a diet less well adapted to the highest altitudes.
In other places it breeds at lower elevations compared to the Himalayan habitat. It normally breeds from 4,130–9,450 ft (1258.8–2880.3 meters) in Europe and 9,450–12,800 ft (2,880.3–3901.4 m) in Morocco. The birds have been observed following mountaineers going to scale the Mount Everest. One party of the birds followed members of a British Everest expedition almost to the summit, 29,000 ft (8839.2 m), in search of food.
Pyrrhocorax graculus usually nest in cavities and fissures on inaccessible rock faces, although locally they use holes between rocks in fields, and forage in open habitats such as alpine meadows and scree slopes to the tree line or lower. In winter they often congregate around human settlements, ski resorts, hotels and other tourist facilities. Its penchant for waiting by hotel windows for food is popular with tourists. In case the weather turns bad, they descend to lower altitudes.
Yellow-billed chough is one of only two species in the genus Pyrrhocorax. Glossy black in colour with yellow beak, red legs, and distinctive call, its eggs too have adaptations to the thin atmosphere that improves oxygen take-up and reduces water loss. It breeds in mountains from Spain eastwards through southern Europe and the Alps across Central Asia and the Himalayas to western China. There are also populations in Morocco, Corsica and Crete. It is a non-migratory resident throughout its range, although Moroccan birds have established a small colony near Málaga in southern Spain, and wanderers have reached Czechoslovakia, Gibraltar, Hungary and Cyprus.
Bearded vulture, great bearded vulture or lammergeier (Gypaetus barbatus)
The bird is not only high-flying but also lives on high mountain cliffs of Asia, Africa, and Europe. Also known as Himalayan bearded-vulture, it has been observed flying at heights up to 24,000 feet (7,315m) on the Mount Everest.
Living exclusively on bone marrow
Like others this vulture is also a scavenger and is the only living bird species that specializes in feeding on bone marrow by scooping it from the core of the bone with the help of its long, slim tongue, shaped like a narrow trowel. Feeding mostly on carrion it usually avoids the actual meat, however, and lives on a diet that is typically 85 to 90 per cent bone marrow. The bird can swallow whole or bite through brittle bones up to the size of a lamb’s femur and its extremely strong digestive juices quickly dissolve even large pieces.
The bird is a specialist in taking out marrow even if the bone is too hard. It has learned to crack large and heavy bones by throwing them from a height. Whenever there is such problem the bird carries the bone to a height of 160–490 ft (50–150 m) and drops it onto rocks below, smashing it into smaller pieces and exposing the nutritious marrow. Bearded vultures can fly with bones up to 10 cm (3.9 in) in diameter and weighing over 4 kg (8.8 lb), or nearly equal to their own weight. After dropping the bone, the vulture comes down to inspect it and if not satisfied it may repeat the act. This is a learned skill that requires extensive practice by immature birds and takes up to seven years to master it. This is an example of tool using by birds, which only about 30-32 species employ.
Andean Condor (Vultur gryphus)
Member of the New World vulture family Cathartidae, this South American bird is the only member of the genus Vultur that can be seen soaring at a height of 21,300 feet (6,492m).
Resident of Andes Mountains and adjacent Pacific coasts of western South America, this is the largest flying bird in the world by combined measurement of weight and wingspan. Andean Condors have maximum wingspan of 10 ft 10 in (3.3 m) exceeded only by the wingspans of four water and seabirds — roughly 11 ft 6 in (3.5 m) maximum of the wandering albatross, southern royal albatross, great white pelican and the Dalmatian pelican.
Largest and heaviest of all raptors, they can weigh up to 13.5 kg. These voracious eaters are basically scavengers and feed on dead bodies, gobbling up considerable amount of meat in one go.
As far as the longest wingspan of any land bird is concerned, Andean condor and marabou stork, another carrion eater of Africa, are both claimant of this distinction. Both have wingspan of approximately 11ft. They have long, broad wings with fingered primaries best suited for soaring flight.
Condors are known for soaring with their wings held horizontally and the primary feathers bent upwards at the tips. They flap their wings on rising from the ground, but after attaining a moderate elevation wings are flapped very rarely, relying on thermals to stay aloft. Cruising on air currents, they can travel up to 110 km without flapping, the longest distance any bird can travel like this. They utilize the up-drafts generated by warm air currents to keep themselves aloft.
Mallard duck (Anas platyrhynchos)
Mallards are medium-sized waterfowls and are often slightly heavier than most other surface feeding ducks (dabbling ducks). Weighing 0.72–1.58 kg (1.6–3.5 lb) they are extremely good flyers and can reach great heights. A group of these birds was observed flying at a height of 21,000 feet (6,400m) over Nevada. They are strongly migratory in the northern parts of their breeding range, and winter farther south.
The mallard is widely distributed across the Northern and Southern Hemispheres; in North America from southern and central Alaska to Mexico, the Hawaiian Islands, across Eurasia, from Iceland and southern Greenland and parts of Morocco (North Africa) in the west, Scandinavia to the north, and to Siberia, Japan, and South Korea, in the east, Australia and New Zealand in the Southern hemisphere.
Bar-tailed godwit (Limosa lapponica)
Bar-tailed godwits are not only high-flying birds reaching 20,000 ft (6,096 m) while migrating; they and the Bristle-thighed Curlews, also undertake the longest non-stop flight of any bird, without pausing to feed, drink or take rest. During a study in 2007 some Bar-tailed godwits were tagged in New Zealand and were tracked by satellite to the Yellow Sea in China.
According to Dr. Clive Minton, (Australasian Wader Studies Group): “The distance between these two locations is 9,575 km (5,950 mi), but the actual track flown by the bird was 11,026 km (6,851 mi). This was the longest known non-stop flight of any bird. The flight took approximately nine days. At least three other birds of the same species also appear to have reached the Yellow Sea after non-stop flights from New Zealand.”
One specific female of the flock, nicknamed “E7″, flew onward from China to Alaska and stayed there for the breeding season. Then on 29 August 2007 she departed on a non-stop flight from the Avinof Peninsula in western Alaska to the Piako River near Thames, New Zealand, setting a new known flight record of 11,680 km (7,258 mi).
These birds migrate in flocks to coastal East Asia, Alaska, Australia, Africa, northwestern Europe and New Zealand, where the sub-species Limosa lapponica baueri is called ‘Kūaka’ in Maori.
They are large wading birds in the family Scolopacidae. The genus name Limosa is from Latin and means “muddy”, from limus, “mud”. The specific lapponica refers to Lapland. The English term “godwit” was first recorded in about 1416–17 and is believed to imitate the bird’s call.
Bar-tailed godwits breed on Arctic coasts and tundra mainly in the Old World, and winter on coasts in temperate and tropical regions of the Old World and of Australia and New Zealand.
White Stork (Ciconia ciconia)
White storks are not only long-distance migrants, but can attain 16,000 feet (4,876m) high altitude while migrating.
White storks fly south from their summer breeding grounds in Europe and head for Kenya and Uganda south to the Cape Province of South Africa. Some diverge westwards into western Sudan and Chad, and may reach Nigeria. In spring, the birds return north and arrive back in Europe around late March and April, after an average journey of 49 days.
They rely on the uplift of air thermals to soar and glide the long distances of their annual migrations between Europe and sub-Saharan Africa.