White parrots from Indonesia, called Goffin's cockatoos, were already known to make tools out of tree branches, but now they have impressively passed the 'tool kit test' - only achieved by chimpanzees and humans.
It means the brainy birds can plan which tools are needed and carry the right 'tool kit' for the job.
The experiment involves using cockatoos' favourite food - cashew nuts - in a kind of transparent vending machine for birds.
The experiment involves using cockatoos' favourite food - cashew nuts - in a kind of transparent vending machine for birds.
To get the treats to drop out, each cockatoo first had to use a pointy tool to pierce a paper screen in front of the nut.
Then they could use a bendy plastic tool - a straw cut in half lengthways - to push the nut off of a stand so it falls out.
First, the cockatoos figured out how to use the two tools - within 35 seconds, for two of the brightest birds.
But the groundbreaking part was when four out of five birds showed they could plan the right set of tools for the job, pick them up and set off with them on their beaks.
Antonio Osuna-Mascaro, from the University of Veterinary Medicine, Vienna, which published the study in Current Biology, said: 'This behaviour is absolutely stunning, as it shows these cockatoos are so intelligent that they have a mental representation of the tools they will use.'
To get the treats to drop out, each cockatoo first had to use a pointy tool to pierce a paper screen in front of the nut
He added: 'When something needs fixing at home, you don't keep going back and forth for a hammer or nail, you pick up your tool kit.
'You have an idea of which tools will be needed for the job - and this study suggests that cockatoos do as well.'
The study, published in the journal Current Biology, started with ten Goffin's cockatoos.
Five of the birds consistently worked out how to use the pointy and bendy tools to get a snack and were willing to do so.
The 'Alpha male' of the group, Figaro, was one of two birds which impressively managed the task first time within 35 seconds.
The five successful birds were then presented with the tools, and iconwin required to travel three different ways to the clear box with the nut inside.
The experiment was designed to show that birds could plan to take the tool kit they would need - rather than just picking up tools when they became useful.
Then they could use a bendy plastic tool - a straw cut in half lengthways - to push the nut off of a stand so it falls out
In total, four out of five birds learned to carry two tools for the tasks, so that they only had to make one trip.
The cockatoos even worked out how to slot the wooden tool inside the plastic one, to carry them more easily.
Chimpanzees have similarly been found to carry two tools, to pierce a hole in the top of a termite mound with one, and put another inside the mound to draw out the bugs inside.
Dr Osuna-Mascaró said: 'With this experiment we can say that, like chimpanzees, Goffin's cockatoos not only appear to be to using tool sets, but they know that they are using tool sets.'
Indonesia