As many a damaged campervan owner would tell you, kea are notoriously cheeky.

But when they steal from tourists and vandalise vehicles, are they simply playing, or is there a bigger picture we're not seeing?

Researchers suspect our native alpine parrot is little different from a human infant, learning about their world by interacting with objects around them.

"There's a big mystery that's quite relevant to New Zealand, and that is, why are kea so curious?" said the University of Auckland's Dr Alex Taylor, a co-author of a new study published today in Royal Society Open Science.

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"The main question we were interested in was, why do kea choose exploratory behaviour?"

One possibility was that kea were simply playing to pass the time; another more tantalising idea was that they were actually schooling themselves.

The researchers sought to test out the theory in experiments involving kea and another famously clever bird species, New Caledonian crows.

They presented both species with a number of objects, some of which had the potential to be tools.

The birds were then faced with a tool-use task, and had to choose from the objects they had explored.

"We thought, what if they're playing away, and they discover how an object feels, how much it weighs, or how it works, and they use it as a tool later on when it comes to problem solving?" Taylor said.

"So what we thought we'd see was when we gave kea and New Caledonian crows the opportunity to play and interact with objects, that they would basically figure out that one was heavy and one was light.

"And when we gave them the choice of an object to drop down a tube to trigger a platform, that they would choose the heavy one rather than the light one."

Both kea and crows did better than could be explained by chance alone, and proved better at choosing tools when they had explored them compared to when they had not.

This suggested that, much like human infants, the birds' exploration allows them to gather important information about their physical world.

Taylor said the study might offer one of the first clues to ultimately solving the mystery of kea curiosity.