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The African sacred ibis (Threskiornis aethiopicus) is a species of ibis, a wading bird of the Threskiornithidae family. It is native to Africa and the Middle East. It is especially known for its role in the religion of the Ancient Egyptians, where it was linked to the god Thoth.
An adult individual is 68 cm (27 in) long with all-white body plumage apart from dark plumes on the rump. Wingspan is 112 to 124 cm (44 to 49 in) and body weight 1.35 to 1.5 kg (3.0 to 3.3 lb). Males are generally slightly larger than females.
The bald head and neck, thick curved bill and legs are black. The white wings show a black rear border in flight. The eyes are brown with a dark red orbital ring. Sexes are similar, but juveniles have dirty white plumage, a smaller bill and some feathering on the neck, greenish-brown scapulars and more black on the primary coverts. This bird is usually silent, but occasionally makes some croaking noises, unlike its vocal relative, the hadada ibis.
The sacred ibis breeds in Sub-Saharan Africa and southeastern Iraq. A number of populations are migrant with the rains; some of the South African birds migrate 1,500 km as far north as Zambia, the African birds north of the equator migrate in the opposite direction. The Iraqi population usually migrates to southwestern Iran, but wandering vagrants have been seen as far south as Oman (rare, but regular) and as far north as the Caspian coasts of Kazakhstan and Russia (before 1945).
It was formerly found in Egypt, where it was commonly venerated and mummified as a votive offering to the god Thoth. For many centuries until the Roman period the main temples buried a few dozen of thousands of birds a year, and to sustain sufficient numbers for the demand for sacrifices by pilgrims from all over Egypt, dozens of ibis breeding farms (called ibiotropheia by Herodotus) were established, initially throughout Egypt, but later centralised around the main temples, each producing around a thousand mummies annually. Aristotle mentions in c. 350 BC that many sacred ibises are found all over Egypt Strabo, writing around 20 AD, mentions large amounts of the birds in the streets of Alexandria, where he was living at the time; picking through the trash, attacking provisions, and defiling everything with their dung.
Pierre Belon notes the many ibises in Egypt during his travels there in the late 1540s (he thought they were an odd type of stork).Benoît de Maillet, in his Description de l'Egypte (1735) relates that at the turn of the 17th century, when the great caravans travelled yearly to Mecca, great clouds of ibises would follow them from Egypt for over a hundred leagues into the desert to feed on the dung left at the encampments.By 1850, however, the species had disappeared from Egypt both as a breeding and migrant population, with the last, albeit questionable, sighting in 1864.
The species didn't breed in southern Africa before the beginning of the 20th century, but it has benefited from irrigation, dams, and commercial agricultural practices such as dung heaps, carrion and refuse tips. It began to breed in the early 20th century, and in the 1970s the first colonies of ibises were recorded in Zimbabwe and South Africa. Its population for example expanded 2-3-fold during the period between 1972-1995 in Orange Free State. It is now found throughout southern Africa. The species is a common resident in most parts of South Africa. Local numbers are swollen in summer by individuals migrating southwards from the equator.
Elsewhere in Africa it occurs throughout the continent south of the Sahara, but it is largely absent in the deserts of southwestern Africa (i.e. the Namib, the Karoo, the Kalahari) and probably the rainforests of the Congo. In west Africa it is fairly uncommon across the Sahel, except for the major floodplain systems. It can commonly found breeding along the Niger, in the Inner Niger Delta of Mali, the Logone of C.A.R., Lac Fitri in Chad, the Saloum Delta of Senegal, and other localities in relatively small numbers such as in The Gambia. It is common across eastern Africa and southern Africa. Large numbers can be found in the Sudd swamps and Lake Kundi in Sudan in the dry season. It is fairly widespread along the upper Nile River, and is quite common around Mogadishu, Somalia. In Tanzania there are a number of sites with 500 to 1,000+ birds, totalling some 20,000 birds.
The bird is also native to Yemen; in 2003 it bred in large numbers on small islands near Haramous and along the Red Sea coast near Hodeidah and Aden, where it was often found at waste-water treatment plants. It has been recorded nesting on a shipwreck in the Red Sea. It is also seen as a vagrant on Socotra. With the current war and famine, there have been no new census reports on the species in Yemen, however an estimate of approximately 30 mature individuals was given in 2015.
The species was fairly common in Iraq in the first half of the 20th century, but by the late 1960s it had become very scarce, with the population thought to number no more than 200 birds. The population was thought to have suffered greatly during the draining of the marshes of southeastern Iraq starting in the late 1980s, and feared to have disappeared entirely, but it has continuously been observed breeding in a colony in Hawizeh Marsh as of 2008, numbering up to 27 adults. It is also native to Kuwait, where it occurs as an extremely rare migrant, with only two known sightings, the last being a flock of 17 in 2007.
There are no records of the bird in Iran before the 1970s, however small numbers were found overwintering in Khuzestan in 1970. Since the 1990s numbers appear to have slowly increased to a few dozen.
The African sacred ibis occurs in marshy wetlands and mud flats, both inland and on the coast. It preferably nests on trees in or near water. It feeds wading in very shallow wetlands or slowly stomping in wet pastures with soft soil. It will also visit cultivation and rubbish dumps.
The species are predators which feed primarily by day, generally in flocks. The diet consists of mainly insects, worms, crustaceans, molluscs and other invertebrates, as well as various fish, frogs, reptiles, small mammals and carrion.It may also probe into the soil with its long beak for invertebrates such as earthworms.
Sacred ibises were observed to occasionally feed on the contents of pelican eggs broken by Egyptian vultures in the mixed colonies of the ibises, cormorants, pelicans and Abdim's storks at Lake Shala in Ethiopia.On Central Island in Lake Turkana sacred ibises were noted to incidentally eat Nile crocodile eggs excavated by Nile monitors.Most recently, in 2006, observations were reported from a large mixed colony on Bird Island (called Penguin Island in the article) in South Africa, where 10,000 pairs of gannets nested, together with 4800 pairs of Cape cormorant and other species such as gulls and jackass penguin. Within a period of 3 years, a few specialized sacred ibis individuals out of the 400 that roosted on the island had fed on at least 152 eggs of the cormorant (other species were even more ovivorous).
In a study of pellets and stomachs contents of nestlings in the Free State, South Africa, food is mostly reported to consist of frogs (mainly Amietia angolensis and Xenopus laevis), Potamonautes warreni crabs, blow fly maggots, Sphingidae caterpillars, and adult beetles. During the first 10 days of life nestlings fed mainly on crabs and beetles, and later mainly on Sphingidae caterpillars and more beetles. The breeding colony collected different (proportions of) prey the subsequent year. The food of one one‐month old nestlings at Lake Shala, Ethiopia, consisted of beetle larvae, caterpillars and beetles.In France adult ibises fed largely on the invasive crayfish Procambarus clarkii, for nestlings larvae of Eristalis species are important.
The most important predator of nestlings of the sacred ibis in Kenya is the African fish eagle, which preferentially searches for the largest (sub-)colonies to attack, but in Ethiopia and South Africa it poses less of a threat