Belmore Park, just across Eddy Ave, to be precise, is the spot emerging as a top culinary destination for the ibis – native to wetlands but now probably the city-est of Australia’s city birds.

With its heavy pedestrian traffic, large itinerant population and ideal location between the takeaway restaurant and the train home, Belmore Park is a veritable Hawker’s Alley for the bird we call the “bin chicken”.

If they’re forced to, they’ll go paleo with a diet of earthworms. But in a city filled with restaurants that pretend they’re foragers, the bin chicken is the real deal. It loves nothing more than gobbling up cold chips – and white bread from the hands of bird lovers.

There are about ten times as many “tip turkeys” in Belmore Park than other parks. But for those with an interest, the mystery remained why they leave Belmore Park on rainy days – while other parks manage to retain their population of “trash vultures”.

Now former University of Wollongong honours student Matt Chard is the main author on a paper that has got to the bottom of it. 

Worms come to the surface when it rains, giving the ibis a replacement when humans are taking shelter indoors and not feeding them. Like an ibis, Mr Chard foraged for worms.

Building on work by Dr Richard Major of the Australian Museum, Mr Chard used a chlorine solution to draw worms out of the ground, washing them before returning them to softer ground and counting their numbers.

And he found worms were in short supply in Belmore Park – the Domain had six times as many worms. Without a food source to replace humans in wet weather, the ibis have to go elsewhere.

So the presence of so many ibis, drawn by human food scraps, destroys the worm population, leaving ibis without a protein-rich diet … which in turn makes them more dependent on human-sourced bin produce, but only on dry days.

There must be a lesson there.

“Humans have complex interactions with wildlife and it is accentuated in landscapes where human impacts are high,” is how Mr Chard puts it.

Could we say, dear bin chicken, in other words, get out of the city?

Not so easy, says UoW professor Kristine French, one of Mr Chard’s supervisors and a co-author of the PLOS ONE paper.

“Ibis have lost much of their habitat in the wetlands in Central NSW and now rely on living in Sydney and other coastal areas,” she said.

“Living in cities is important for their conservation and we must learn to live with these animals and understand their needs. Matt’s work is a part of that research goal.”

Mr Chard said no worms suffered “long-term harm” during his work.