First they opened bins, now crackles of Sydney's sulphur-crested cockatoos (Cacatua galerita) have been recorded by scientists waiting their turn to use drinking fountains.
The birds, which roost around the Western Sydney Parklands, have figured out how to operate twist-handled bubblers, according to a new study.
The behaviour was observed in a group of up to 200 birds, scientists report in The Royal Society Biology Letters.
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Study co-author Lucy Aplin, a behavioural and cognitive ecologist from the Australian National University, said it took coordinated actions for the birds to access water from the spring-loaded fountains.
"It's just one of your bog-standard old-fashioned drinking fountains that you find all across sports fields in Australia," she said.
"They [cockatoos] hold on to the stem and they twist with their foot but then they have to lean their weight while they twist as well.
Dr Aplin said the whole process looked a "bit funny".
"It's a bit of an awkward body position they have to hold, but it's pretty impressive," she said.
Watching the 'watering hole'
Sulphur-crested cockatoos are well known for their urban antics causing havoc on bin night in more than 60 suburbs in Sydney's south.
But the population in Western Sydney is a different mob.
After the study's lead author, the Max Planck Institute of Animal Behavior's Barbara Klump, saw the drinking behaviour first-hand, she set up a study to track the behaviour of cockatoos around a well-used drinking fountain.
First, the researchers identified 24 individual birds by painting them with dots, then they used wildlife cameras to monitor attempts to use the bubblers by these and other birds in the local area.
Over 44 days, the cameras recorded 525 attempts and collectively the birds were successful 41 per cent of the time they tried to drink, with the marked birds being slightly more successful.
Dr Aplin said about 70 per cent of the local birds, which roosted close by, were using the drinking fountain.
"They use them as a preferred place to drink no matter whether it's hot or if there's other water sources available," she said.
All ages and sexes participated too, unlike with the bin-opening behaviour, which is mostly done by males.
"Something about the bin opening requires strength, and that's why it's male-biased," Dr Aplin said.
"[Drinking from bubblers is] a very complex behaviour that requires lots of different fine scale motor actions, but not brute force."
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Cockatoo brains are large for their bodies
Cockatoos are able to work out something tricky like turning a handle because they have brains that are relatively large for their bodies.
Their forebrain, which deals with advanced cognitive abilities like tool use, is packed full of neurons, like chimpanzees, which also excel at complex problems.
Alex Taylor, who studies biological intelligence at the Autonomous University of Barcelona, said it was clearly tricky to get a tap to work when you had the body of a bird.
"Which explains why birds are only successful 50 per cent of the time when trying to use the tap," Dr Taylor, who was not involved with the research, said.
"Still this is a pretty good success rate on a hot day when you are thirsty."
Dr Taylor said the study raised the question of why only a single species was exploiting human water taps and not others.
Why are the birds using the bubbler?
The exact reason the cockatoos use the bubbler instead of other water sources like a lake or creek is not understood.
But there are several hypotheses that researchers want to test.
"One possibility is the water just tastes better," Dr Aplin said.
The taste of the water or safety of an elevated water source are two of the theories for why cockatoos use bubblers. (Instagram: Flutterby_di)
That is a theory Irene Pepperberg, an animal behaviourist from Boston University who was not involved in the study, also thought was possible.
she said.
"The resource is unlimited, so it is probably worth it to keep trying until they figure out the successful behaviour and, if they fail, they seem to have other water sources.
"The birds do seem to learn about the source from one another; whether they learn the specific technique from each other is a bit less clear."
Cockatoos are known for having large brains for their bodies which allows them to innovate and work out complex tasks. (ABC: Tim Swanston)
Another idea is the birds like how the bubblers sit about 1 metre off the ground.
Alice Auersperg, a cognitive biologist from the University of Veterinary Medicine who was not part of the study, said this was because drinking from a ground source was risky and left them exposed to predators.
But she said another reason they might use the bubblers was because the birds liked to undertake an activity even if there was no food reward.
Dr Pepperberg said she recently did a study with umbrella cockatoos where 40 per cent of the time they chose to shell nuts rather than eat ones that were already shelled.
How you can help future studies
The team behind the new bubbler research hopes to drill down into the reasons behind the behaviour as well as other cockatoo innovations in future studies.
Dr Aplin said she had received other reports of cockatoos using bubblers with levers and unzipping bags to access lunch boxes.
She encouraged people who saw these kinds of behaviour to report it through the Big City Birds App.
Gisela Kaplan, an emeritus professor of animal behaviour from the University of New England, said several bird species seemed to exploit taps in the outback in different ways to cockatoos.
"The moment [the taps] are used, the birds now fly in and take the drops that fall down and then, once the person has left, also lick out the last drops that are in the tap," Professor Kaplan, who was not involved with the study, said.
She said she had witnessed a great bowerbird in Larrimah, Northern Territory, work with its beak at a tap nozzle attachment until water drops were generated.
While not all birds can operate drinking fountains, many, like this great bowerbird, will exploit taps for a sip after humans use them. (Supplied: Gisela Kaplan)
Dr Aplin said ultimately, there was an important message behind all these observed behaviours beyond just funny anecdotes.
"Urban animals that are adaptable and have expressed behavioural flexibility and have large brains are going to try and use the habitats that we provide them with," she said.
"So if we want to increase biodiversity in cities, we need to think about increasing the sort of habitat requirements for species that might not be so adaptable."
On the other hand, Dr Aplin added, we could also use urban design to manage those species that are more adaptable.