Heaviest Flying Birds
Kori bustard (Ardeotis Koriis) and the great bustard (Otis tarda) are the heaviest flying birds on the planet. On an average both weigh 19-20 kg (42 pounds) each, but in extreme examples cocks have also been recorded at 21 kg (46.2971 pounds) . Males of both species are much larger and heavier compared to females.
Kori bustards (Ardeotis Koriis)
Kori bustards that are extremely watchful and wary spend most of their time walking on the ground in search of food. They are usually very shy, running or crouching at the first sign of danger, but sometimes they can be completely fearless of humans. Usually they have a hesitant, slow manner of walking, but when any intruder is detected they try to escape detection. Being a large and heavy bird, it avoids flying as far as possible. When alarmed it will first run and, if pushed further, will take to air on the run with much effort, its wings making heavy wingbeats. Once airborne it flies more easily with slow, measured wingbeats.
Native to Africa the bird usually remains low while flying and lands again within sight. After touchdown it keeps its wings spread and only folds them when it has slowed down to a walking speed. This threatened bird has no preen glands, so to keep clean, it produces a powder down. Sun bathing and dust bathing are practiced.
Males that can be more than twice as heavy as the female, mate with as many females as possible, but take no part in raising the young. Nests are shallow hollow on the ground, often disguised by nearby obstructive objects such as trees. The specific epithet kori is derived from the Tswana name for the bird – Kgori.
The kori bustard is found throughout southern Africa, except in densely wooded areas. They are common in Botswana and Namibia, extending into southern Angola and marginally into southwestern Zambia. In Zimbabwe they are generally sparse but locally common, particularly on the central plateau. They are also found in southern Mozambique and the eastern lowveld of South Africa. The species is common in Tanzania. A geographically disjunct population also occurs in the deserts and savanna of northeastern Africa. Kenya may hold the largest population of kori bustards of any country and it can even border on abundant in the North Eastern Province. They are usually resident in their range, with some random, nomadic movement following rainfall.
Species occurs in open grassy areas, often characterized by sandy soil, especially Kalahari sands, and short grass usually near the cover of isolated clumps of trees or bushes. It may be found in plains, arid plateaus, highveld grassland, arid scrub, lightly wooded savanna, open dry bushveld and semi-desert. Where this species occurs, annual rainfall is quite low, at between 100 and 600 mm (3.9 and 23.6 in).
Breeding habitat is savanna in areas with sparse grass cover and scattered trees and shrubs. For the purpose of nesting they sometimes use hilly areas. They follow fires or herds of foraging ungulates, in order to pick their various foods out of the short grasses. They may also be found in cultivated areas, especially wheat fields with a few scattered trees. In arid grasslands it is found along dry watercourses where patches of trees offer shade during the heat of the day.
Great bustard (Otis tarda)
Great bustards are native to Europe and Asia. In spite of their weight, they migrate nearly 2,500 miles each year. While most long-distance migratory birds glide to conserve their energy, great bustards flap the entire distance, taking frequent breaks to conserve energy. According to a study great bustards take around four months to complete their migration, but spend only 2 to 6 percent of that time airborne.
Heavy birds usually need ‘runways’ to get airborne. Swans use water for the purpose; bustards’ long legs are asset in this respect.
The only member of the genus Otis, it breeds in open grassland and farmland in southern and central Europe, and across temperate Asia. European populations are mainly resident, but Asian birds move further south in winter. Portugal and Spain has about 60 per cent of the world’s population.
The species became extinct in Great Britain when the last bird was shot in 1832. Recent attempts to reintroduce it into the UK have met with limited success. It is classified by the IUCN as “vulnerable”.
This species is gregarious, especially in winter when gatherings of several dozen birds take place. Male and female groups do not mix outside of the breeding season. These birds have stately slow walk but tends to run when disturbed rather than fly. Though the running speeds have not been measured but adult females have been known to outrun red foxes (Vulpes vulpes), which can reach a trotting speed of 48 km/h (30 mph). They are fairly strong fliers, especially during seasonal movements, and can reach speeds of up to 80 km/h (50 mph) in flight.
Both sexes are usually silent but can engage in deep grunts when alarmed or angered. The Asian and Russian populations are migratory and gather in large numbers at pre-migratory sites in order to move collectively to wintering grounds. In the remainder of the range, such as Central Asia, only partial migrations may occur based on seasonal food availability. In the Iberian Peninsula, bustards that engage in migration seem to choose different periods for movements based on sex. No population is known to use the same grounds for wintering and summering.
Other heavy flying birds
Other heavy flying birds include swans, the largest members of the waterfowl family Anatidae. The largest species in this group are mute swan, trumpeter swan, and whooper swan. They can reach a length of over 1.5 m (59 in) and weigh over 15 kg (33 lb). Their wingspans can be over 3.1 m (10 ft). Compared to the closely related geese, they are much larger and have proportionally larger feet and necks.
Condor, a vulture-like bird, is not only a large bird of prey, but also one of the largest flying birds. There are two species; one is found in the Andes Mountains of South America, the other lives in California.
As the name suggests Andean Condors (Vultur gryphus) are residents of Andes Mountains. Cruising on air currents, they can travel up to 110 km without flapping their wings, the longest distance any bird can travel like this. They utilize the up-drafts generated by warm air currents to keep themselves aloft.
Condors are the largest and the heaviest of all raptors with a weight of about 13.5 kg. This carrion feeder can eat considerable amount of meat in one go. As far as the longest wingspan of any land bird is concerned, Andean condor and marabou stork (Leptoptilos crumenifer), another carrion eater of Africa are the two claimant of this distinction. Both have wingspan of about 11 ft. They have long, broad wings with fingered primaries best suited for soaring flight.
California condor (Gymnogyps californianus) is one of the rarest birds. Weighing around 10 kg, with a wingspan of about 3 metres, it is North America’s largest flying land bird.