Australian White Ibis

Threskiornis molucca

White Ibis. Photo: Kevin Williams.

Older texts refer to the Australian White Ibis as the “Sacred Ibis”. That is because, the Australian White Ibis and the Sacred Ibis of Africa were at one time thought to constitute a single species. Now, however, the Australian White Ibis is regarded as a separate species in its own right. Their numbers have increased rapidly over recent years, particularly in towns, where they have learnt to scavenge human waste. In fact they have become a nuisance in certain areas.

 

White Ibis. Photo: Trevor Cox

The Australian White Ibis eats a wide variety of prey items – frogs, fish, freshwater crayfish and other crustaceans, earthworms, insects, snakes, mice, and carrion. They forage by walking slowly and pecking at items on the surface, or probing with their long bill.

The time of breeding is much affected by water supply. Nesting tends to be colonial, sometimes in very large numbers. The nest can be a cup of twigs lined with leaves, or, in swamps, be a cup constructed of reeds. The clutch ranges from 1 to 4 eggs. The chicks are covered in blackish-brown down.

Description

The Australian Ibis is a large bird, weighing between 1.4 and 2.5 kg. The sexes are alike but the male is larger and has a longer bill. The body plumage is largely white except for the tertials which are greenish-black, and lacy, and cover the rump and tail. The primaries are also tipped greenish-black. The tail feathers are tinged yellow. The head and top of the neck are bare, coloured black and have pink horizontal bars on the nape. On the underwing there are strips of bare pinkish skin marking the wing bones. In the breeding season, stiff cream-coloured plumes form on the upper breast, and the bare skin strips under the wing turn pink-red. Immatures have the head and neck completely feathered.

Where to find it

Australian White Ibis are common through the wetter parts South Australia, uncommon in drier areas, and absent from the deserts of the north west. They are found in all manner of wetlands, inland as well as in sheltered marine habitats (tidal mudflats, mangroves, salt pans and coastal lagoons). They may also be found far from wetlands, including in human created habitats such as rubbish dumps, gardens, parks and sewage works. Adults are largely sedentary but with migratory movements in some areas (north in winter, returning in summer).