[order] CICONIIFORMES | [family] Threskiornithidae | [latin] Threskiornis molucca | [UK] Australian White Ibis | [FR] Ibis a cour noir | [DE] Australischer Ibis | [ES] Ibis moluqueno | [NL] Australische Witte Ibis | [Authority] Cuvier, 1829

Australian White Ibis determination

Threskiornis is a genus of , wading birds of the family Threskiornithidae. They occur in the warmer parts of the Old World in southern Asia, Australasia and sub-Saharan Africa. They are colonial breeders, which build a stick nest in a tree or bush and lay 2-4 eggs. They occur in marshy wetlands and feed on various fish, frogs, crustaceans and insects. Adult Threskiornis ibises are typically 75cm long and have white body plumage. The bald head, neck and legs are black. The bill is thick and curved. Sexes are similar, but juveniles have whiter necks duller plumage. The Straw-necked Ibis differs from the other species in having dark upperparts, and is some times placed in the separate genus Carphibis (Jameson, 1835)as Carphibis spinicollis.

copyright: Stephen Wallace

The Australian White Ibis is identified by its almost entirely white body plumage and black head and neck. The head is featherless and its black bill is long and down-curved. During the breeding season the small patch of skin on the under-surface of the wing changes from dull pink to dark scarlet. Adult birds have a tuft of cream plumes on the base of the neck. Females differ from males by being slightly smaller, with shorter bills. Young birds are similar to adults, but have the neck covered with black feathers. In flight, flocks of Australian White Ibis form distinctive V-shaped flight patterns. Another common name for this bird is Sacred Ibis, but this more appropriately refers to a closely related African species.

The Australian White Ibis can be observed in all but the driest habitats. Preferred habitats include swamps, lagoons, floodplains and grasslands, but it has also become a successful inhabitant of urban parks and gardens.

The Australian White Ibis' range of food includes both terrestrial and aquatic invertebrates and human scraps. The most favoured foods are crayfish and mussels, which the bird obtains by digging with its long bill. Mussels are opened by hammering them on a hard surface to reveal the soft body inside.

This species has a very large range, and hence does not approach the thresholds for Vulnerable under the range size criterion (Extent of Occurrence <20,000 km2 combined with a declining or fluctuating range size, habitat extent/quality, or population size and a small number of locations or severe fragmentation). The population trend appears to be fluctuating, and hence the species does not approach the thresholds for Vulnerable under the population trend criterion (>30% decline over ten years or three generations). The population size is very large, and hence does not approach the thresholds for Vulnerable under the population size criterion (<10,000 mature individuals with a continuing decline estimated to be >10% in ten years or three generations, or with a specified population structure). For these reasons the species is evaluated as Least Concern.

The male Australian White Ibis secures a pairing territory on a branch of a tall tree in order to attract a female. The courtship ceremony involves the male putting on a noisy display, as well as showing aggression towards other males. When a female arrives, the male attracts her by bowing from his branch. He then offers the female a twig, forging a bond when she grasps it and they begin to preen one another. Once the pair bond is cemented, the birds fly off to build a nest at another location. Australian White Ibis nest in large colonies, often with the Straw-necked Ibis, T. spinicollis. Young are born naked and helpless. One or two broods may be reared in a year. The clutch size is 1-4 eggs which are incubated for about 3 weeks. After hatching the young fledge after another 6-7 weeks. Communal breeding might be possible because of nests found with large clutches.

Most adults sedentary, although throughout range some irregular, nomadic movements occur, sometimes over long distances, and usually related to availability of water. Population of SW Australia partially migratory, apparently moving N in winter, returning S in summer. Young birds disperse widely. Irregular visitor to Tasmania and vagrant to New Zealand. Some movement recorded between NE Australia and New Guinea, and flocks of up to 500 birds have been recorded crossing Torres Strait.

Range: Australasia : widespread. The Australian White Ibis is common and widespread in northern and eastern Australia, and both its range and abundance in western Australia is expanding, despite its absence from Western Australia prior to the 1950s. The species is absent from Tasmania.