Sulphur-crested cockatoos are learning a new skill in suburban neighbourhoods.
Dr John Martin, researcher with the Taronga Conservation Society, told Australian Community Media his colleague, Richard Major, first observed the behaviour in the birds back in 2014.
On bin collection day, the birds were teaching themselves and each other to leverage the lid of the red bin up. Once open, they'd poke through the rubbish to find something edible.
"At this point we've only seen other Sulphur-crested cockatoo learning [to open the bins] and key factor to that is these birds are quite large so some of the corella that are in the landscape might not be big enough to do it," Dr Marin said.
"Equally it's about having the right equipment. So they've got this foot that's really great at gripping.
"The corellas have that but slightly smaller, and they've got this big beak to hold the bin [lid] and manipulate it and turn it over and the corella have a slightly different shaped beak."
In order to understand if the phenomena is an isolated behaviour, the team at Taronga Conservation have launched the Clever Cockie Project online survey.
"We really want people to report whether they are or whether they are not seeing bin opening," Dr Martin said.
"Not seeing it is actually really important to say that it hasn't spread somewhere. So we know that it's spread to 44 different suburbs, but we can see that it hasn't spread to some suburbs that were in that immediate area, and that's because the community had reported they were not seeing it."
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By wing-tagging the birds that have begun opening bins, the researchers have been able to tract their movements across suburbs and see how they're teaching other birds to mimic the reward-seeking behaviour.
"They seem to move in a sort of five to 10 kilometre radius of where they live,"
"Spreading it across the country is going to be a crawl. It is going to take a long time as it spreads from neighbourhoods."
So far, the birds have been clustered around south Sydney, Sutherland, and out towards Wollongong. But it has also been observed in Campbelltown, and near Hornsby in north Sydney.
"The Hornsby one, that could be a bird that has no knowledge of those other birds doing it, but it's just learnt how to do this," Dr Martin said.
"Or it could be a bird that has spread that distance."
What is even stranger is that there has been a bird in Lorne in Victoria that has been observed opening bin lids.
"That is definitely going to be an independent innovation, another bird that's learnt to do the exact same thing. That in our world is super cool."
So far, it seems the cockies are a little shy in getting their weekly treats. They don't tend to venture toward the bin until its been taken to the curbside.
"We only see them when the bins get put out. We've not seen any opening when the bins are back towards the house,"
"Whether the birds are hesitant to be in that closer proximity, which is odd because we're well aware, cockatoos are generally happy to land on people's balconies and take food from them."
Though Dr Martin said it's just as likely a matter of delayed gratification given an abundance of bin treats are likely to be found on the day the bins are taken out to the curbside.
"You'll see birds open the bin, pop the lid and see the bin is only half full they'll just move on. They don't want to sit in an open bin lid so they'll just move on to the next bin. They really like the bins that are full."
But as to who the birds learnt the behaviour in the first place, Dr Martin said "comes back to the question about the chicken or the egg".
"Did they see people opening bins and decide, 'let's see if I can lift that thing up and see what's inside there'. Or what I suspect happened was people occasionally overfill their bins and the lids already partly opened, and then they can put their beak in the bin.
"But at some point the birds had to learn that there was food in there."
In their quest to find their weekly treats though the birds are creating something of a nuisance in the neighbourhoods.
As Dr Martin says, "they'll literally throw the rubbish about" until they find what they're looking for.
"There's an arms race going on here, the humans are fighting back against the cockies and there's a range of methods being used to deter them. Some people have put weights on the lids so they can't open them," Dr Martin said.
To keep the rubbish from ending up in the environment, the bird's new behaviour may even influence human behaviours at a local government level.
"The classic is putting a brick on the lid and you see the cockies push that off. The simple one is, the bins get collected in the morning. If you put the bin out in the morning, rather than in the evening, it's a much shorter time for them to be scavenging," Dr Martin said.
"The catch-22 is sometimes the bins get emptied before the sunrise so that's why people put them out the night before, so maybe we need to have the councils collecting them that little bit later in the day just so people can put them out in the morning and it reduces any afternoon foraging."