Sulphur-crested cockatoos can learn how to flip wheelie bin lids from each other.
People have learned from neighbours how to escalate protection tactics.
The birds have learned to go one better.
Last year, we brought you the disturbing research finding that cockatoos are not bird brains! They are very smart and can learn to flip bin lids open by watching others do it.
The researchers have shifted their study to the antics of the people involved, who now put large rocks and bricks on the bin lids to protect their garbage. Pretty clever!
But locking the bin lid down is not enough. The sulphur-crested cockatoos started shoving the rocks off and raiding the bins.
The development has gained international attention, and one German behavioural ecologist has labelled the rubbish bin goings-on as an innovative arms race between cockies and people.
Richard Major, an ecologist with the Australian Museum, said the study showed social learning on both avian and human sides.
"We've modified an environment, and cockatoos have adapted so well to living with humans.
"Now we're seeing humans adapting to living with them."
The researchers are finding all sorts of clever, but pointless, things humans do to stop the birds.
Some people placed bricks on their bins, while others rigged ropes or water bottles to prevent their lids from being opened.
Still, others jammed shoes in handles by the lid hinge to keep the cockies out.
Humans seem to learn like cockies! Protection tactics were clustered — for instance, streets within a couple of blocks might use bricks more than shoes — suggesting these behaviours were socially learnt from neighbours.
Unsurprisingly, people who lived in suburbs where cockies have been opening bins for more than three years tended to use more extreme methods than those in areas where the lid-flipping behaviour was new.
What is best for your bins depends on how long cockies have been trying to break into them, but researchers advise not to throw away the brick – as it does stop some birds for a while.
The researchers have set their sights on cockies across the nation with their birds-and-bins survey now open Australia-wide.
"We are hoping to see over the long term whether the behaviour keeps spreading and if there is an end to the arms race", Major said.