https://www.theguardian.com/environment/2018/mar/14/mummys-boys-ibises-all-wrapped-up-as-presents-for-the-gods
"Bin chickens"? Not heard that one before.
"Bin chicken' is a common Australian slang for them as they haunt parks and urban spaces in Sydney and I think points north. They are utterly fearless of humans and scavenge litter and bins, hence the name. They also look dirty, probably more from foraging in muddy creeks.
No idea if the name is used elsewhere.
Regards
David F Brown