Sacred Ibis

The African sacred ibis is a wading bird of the family Threskiornithidae, native to much of Africa and small parts of Iraq, Iran and Kuwait. An adult is about 68 cm long with all-white body plumage apart from dark plumes on the rump, and a wingspan of 112 to 124 cm. It feeds mainly by day, generally in flocks, taking insects, worms, crustaceans, molluscs, fish, frogs, reptiles, small mammals and carrion, and it probes the soil with its long beak for earthworms. It is especially known for its role in Ancient Egyptian religion, where it was linked to the god Thoth, although it is now extirpated from Egypt.

About the sacred ibis

The African sacred ibis is a white wading bird with a bald black head and neck and a long, down-curved black bill. It belongs to the ibis and spoonbill family and is native to sub-Saharan Africa and small parts of the Middle East. Ancient Egyptians revered it as a living form of Thoth, the god of wisdom and writing.

Its scientific name is Threskiornis aethiopicus. An adult is about 68 cm (27 in) long, with a wingspan of 112 to 124 cm (44 to 49 in), and weighs 1.35 to 1.5 kg (3.0 to 3.3 lb). Males are usually slightly larger than females, but the sexes look alike.

The body plumage is white, apart from a tuft of blue-black plumes on the back that drapes over the short, square tail and folded wings. In flight, the white wings show a black trailing edge. The bare head and neck are black or dull grey-black, as are the thick, curved bill and the legs. The eyes are brown, ringed with dark red skin, and patches of bare red skin show on the sides of the breast.

Young birds look scruffier, with dirty white plumage, a shorter bill, some feathers on the neck, and more dark color on the wings. The sacred ibis is very closely related to the black-headed ibis of Asia and the Australian white ibis. The three are so similar that some ornithologists treat them as one species, and they often hybridize in mixed flocks. In Australia, the white ibis is often casually called a sacred ibis.

Behavior and diet

Sacred ibises are diurnal and social. They feed by day, usually in flocks, wading in very shallow water or stepping slowly across soft, wet pasture and probing the ground with their long bills for earthworms and other prey. They may fly up to 10 km (6 mi) to reach feeding grounds and gather in communal roosts of up to 300 birds.

The diet is broad. Insects, worms, crustaceans and mollusks form the core, supplemented by fish, frogs, reptiles, small mammals, young birds and carrion, and occasionally seeds. Nestlings in one South African colony were fed mostly on frogs, freshwater crabs, beetles and moth caterpillars. Some sacred ibises have learned to raid other birds' eggs: on one South African island, a few specialized individuals ate at least 152 cormorant eggs over three years. In France, adults feed heavily on invasive crayfish.

They are usually silent, though they sometimes make puppy-like yelps, unlike their noisy relative the hadada ibis. During the breeding season they add squeals, moans and wheezes, and parents use distinct calls to summon chicks back to the nest or to feed.

Breeding usually happens once a year in the wet season: March to August in Africa and April to May in Iraq. Males gather and stake out small display territories, and females choose among them. Pairs are monogamous for the season. They build stick nests in trees, often baobabs, in colonies shared with storks, herons, African spoonbills, darters and cormorants. On offshore islands they often nest on the ground, and large colonies can hold 1,000 birds.

Females lay one to five eggs, and both parents incubate for 21 to 29 days. One parent stays at the nest continuously for the first week after hatching. Chicks fledge at 35 to 40 days, become independent at 44 to 48 days, and reach breeding age at one to five years. The African fish eagle is the main predator of nestlings in Kenya; adults are large enough to discourage most predators.

Range and habitat

The sacred ibis breeds throughout Africa south of the Sahara, though it is largely absent from the Namib, Karoo and Kalahari deserts and probably the Congo rainforest. It is common across East and southern Africa and gathers in large numbers in Sudan's Sudd swamps. In Asia it breeds in southeastern Iraq and Yemen and turns up in small numbers in Iran and Kuwait. Several populations migrate with the rains; some South African birds travel 1,500 km (930 mi) north to Zambia.

It lives in marshy wetlands and mudflats, inland and on the coast, and nests in trees in or near water. It readily uses farmland, wet pastures and rubbish dumps, and has adapted to towns and villages. The species did not breed in southern Africa before the 20th century, but irrigation, dams and farming helped it spread there.

Egypt tells the opposite story. The bird was once abundant there, but by 1850 it had disappeared from the country entirely. It remains extirpated from Egypt.

Birds that escaped from captivity have also founded feral populations in France, Italy, Spain, the Canary Islands, Taiwan, the United Arab Emirates and elsewhere. Since 2016 the European Union has listed it as an invasive species of Union concern, and France and Taiwan have run large culling programs. In Florida, a small population that escaped after Hurricane Andrew in 1992 bred in the Everglades before 75 birds were removed by 2009; the species is believed to be eradicated there.

Conservation status

The African sacred ibis is listed as Least Concern on the IUCN Red List, assessed by BirdLife International in 2018. The global population is estimated at 200,000 to 450,000 birds but appears to be decreasing. It is covered by the Agreement on the Conservation of African-Eurasian Migratory Waterbirds (AEWA).

The Asian populations are small. Iraq's birds dropped to no more than about 200 by the late 1960s, and draining of the Mesopotamian Marshes was feared to have wiped them out, though a colony of up to 27 adults was still breeding in 2008. Yemen's population was estimated at about 30 mature birds in 2015.

The sacred ibis's link to ancient Egypt is famous. For centuries, pilgrims brought ibis offerings to Thoth's temples, and an estimated eight million birds were mummified and buried. DNA studies suggest most were wild-caught rather than farmed.