Australian White Ibis
Other names: Sacred Ibis (a species found in Africa).
Range and lifestyle: Resident in wetter parts of Australia, but can fly long distances.
Food: Human refuse, crayfish, frogs, insects, and more.
Breeding: Mainly winter and spring in warmer regions, but most of the year in Brisbane. Nests are loose platforms of sticks built in trees or trampled reeds. Both sexes incubate the 2-4 white eggs for about 3 weeks, and feed chicks in nest for 7 weeks.
Despite being a very intelligent and fascinating species, the Australian White Ibis is better known among city-dwelling people as the “bin chicken” or “bin chook” because of its tendency to scavenge food wastes from rubbish bins in parks and school grounds within Brisbane and other capital cities. But it hasn’t always been so. Indeed White Ibis were uncommon in Brisbane before the 1970s, and their numbers seem to have increased dramatically just in the last 10 years. Many people now consider the ibis as a pest, mainly because of their scavenging habits, dirtiness and smell. But the reason for their scavenging is that humans throw away enormous amounts of food each day, thereby providing ibis with a constant supply of food in thousands of rubbish bins and many council tips. In addition, people in outdoor cafes and picnic areas often feed ibis, unthinkingly showing these intelligent birds that food can be found on and under tables. There is a possibility that ibis can transmit diseases to humans in such places, and because of this risk, and many public complaints, councils have been forced to “control” ibis by destroying their nests and eggs.
Because of the sudden population boom of ibis, some people believe that the ibis is not native and has been introduced from elsewhere. This is wrong. Like most ibis species, our White Ibis is mainly a bird of wetlands, feeding on aquatic animals, such as frogs and crayfish found in shallow water around inland swamps, lakes and rivers, as well as shrimps and molluscs in the mud of coastal mangroves. And like most waterbirds, it breeds in colonies, sometimes very large, with many pairs nesting in each tree, the nests often so close that they touch. In the past, the vast majority of ibis colonies were on our inland rivers, though due to the cycles of droughts and floods, their size varied enormously from year to year.
In the 1960s and 70s, zoo keepers captured and kept ibis in aviaries, but when these birds bred and had young, some were released into the zoo grounds with little thought about the consequences. These free birds quickly established breeding colonies, and probably attracted other ibis that had migrated from the outback to the coastal cities during a long period of drought. Meanwhile, the increasing use of water by farmers growing crops changed the flow of inland rivers and drained the wetlands, while cattle and sheep degraded their shores. Consequently, inland populations of ibis have declined, and instead of migrating to and from the coast, many are now resident in cities, which provide reliable water, food and breeding habitat year-round. In summary, despite suffering from the abuse of inland rivers by many farmers, the Australian White Ibis is one of the relatively few native species that has learnt to exploit a human-dominated environment. Instead of being treated as a nuisance, it should be appreciated and respected as a clever and marvelous bird.
Text © Richard Noske 2019 CC BY-NC-SA