The rise of the ibis in Sydney may be the result of a 1970s Taronga Zoo breeding program, the ABC reports.
In 1973, 19 ibis from Healesville in Victoria were held at Taronga and encouraged to breed as free ranging birds.
A recently unearthed report on the program described the humble ‘bin chicken’ as being “among the most graceful and decorative of Australian birds.”
The ibis population of Sydney is now estimated to have risen to around 10,000.
Australian Museum principal research scientist Richard Major has been studying ibis for over three decades and is reluctant to give credit (or blame) to Taronga for the proliferation of the birds.
However, he said it likely helped the birds adapt to city living.
“The birds had visited Sydney in the past, and there are records of birds in the 1970s visiting Sydney, [but] there are no breeding records in Sydney until the 1980s,” he said.
Major said a more plausible reason for the population boost was environmental degradation, saying that there are far fewer ibis in the Murray-Darling basin than in the 1980s.
“They’ve probably used the coast as a drought refuge when they weren’t getting the freshwater wetland support,” he said.