The Australian White Ibis Threskiornis molucca is very closely related to the Sacred Ibis T. aethiopica and from time to time its identification has shifted back and forth. Here I’ll call it the white ibis, since there are no other species like it in Australia. Like its close relative the straw-necked ibis, the white ibis devours huge numbers of mice and locusts, making it a particularly valuable bird to humans. Sadly, its less discerning nature and its prevalence among garbage tips and public parks, where it is often grimy and vaguely scary (not really threatening at all really) to toddlers, have made it a rather unfashionable, even slightly detestable species in the refined suburbs. This is a great pity and very shortsighted of we extremely self-centred humans, after all, this species removes so much filth from our own ecosystems it should be welcomed instead of being shunned.
The Egyptians recognised this highly nomadic species and its role in clearing up plagues and helping agriculture, as well as its uncanny ability to turn up at just the right time to avert catastrophe and starvation for them. It should be no wonder then that they incorporated its head onto a human body and worshiped it as Thoth, their god of wisdom and learning. Thousands of mummified sacred ibises litter the tombs in that faraway land. We, with our advanced technology but far more alienated from the real and natural worlds, loathe it as Filth, the big associate of ravens, seagulls and other scavengers of the rubbish we produce constantly but place out of our sight in the bushland above Sydney’s drinking water source. Of course many other people, including me, regard it as an interesting, rather cool bird.
As their name suggests, when not dirty, white ibis are covered in white feathers, but have white tails, heads and necks, as well as black tips to their flight feathers, seen when their wing is outstretched, and making their rump look black when their wings are folded. Their bills and legs are black as well. Like all ibis they have a distinct curved bill, a shape that gives the strength needed to probe in mud and soft earth, where they pull out grubs and other insects, as well as buried frogs and plague minnows. Their young have murky, black feathered heads and shorter, straighter bills than the adults.
The photo below shows the adults distinctly. They have leathery, naked black heads with short pink stripes or patches on the crown. The naked head makes it far easier to keep clean when it is deep in mud or rotting stuff. They have bare scarlet flesh showing on their underwings. The bird on the far left of the photo clearly shows its black wing-tips. They also have black lacy feathers that hang over their tails, again unlike the juveniles. To add to the soiled effect, however, their white feathers can also have a yellowish tinge.
White ibis are the most commonly seen ibis in urban areas, but are also quite common in rural areas. Like other ibis, they need trees over water in which to breed and so also need the Riverina and floods to reproduce, however, they are rather less fussy and will accept lesser real estate including trampled reeds to nest in. They readily seek out human environments, from which they can be guaranteed a feast and so are often seen in city parks, gardens, paddocks/wasteland and tips. They happily mingle with other species of ibis, in fact, any species of bird so long as they are unlikely to get eaten. they were seldom seen at all in the Goulburn Wetlands from 2008 until the 2011/2012 floods. Since then they have become abundant in the wetlands, sometimes forming flocks numbering in the hundreds.
Like straw-necked ibis, white ibis will often fly long distances in formation, either a wiggly snake-like line or a V-shaped formation. This enables birds following the lead to use far less energy and so enables them to fly at significantly longer distances than they might otherwise. When the lead bird gets tired it moves backward and another bird takes its place. As a result white ibis can fly very long distances, such as between Victoria and New Guinea. When flying shorter distances, such as when they are disturbed, they will circle en masse before settling down again. Being large birds, white ibis will also avail themselves of warm air pockets (thermals) and will simply glide around the rising air to be lifted to higher altitudes ready to fly far away.