The intellect of the kea may have surpassed their natural abilities, researchers say, after proving the birds can use sticks to open stoat traps.

Footage of one of the alpine parrots opening a trap in Fiordland's Murchison Mountains – and more than 200 sticks found in traps in the takahē conservation area over a two year period – are strong evidence of the first tool use by non-human animals in New Zealand's natural environment.

The finding could open doors for further study on the cognitive limitations, or lack thereof, of other animals, the researchers said.

STUFF Kea are smarter than we think.

Their study, published on Monday, argues "cognitive constraints" previously prevented kea from creating and using tools to forage, but the birds developed the rare skill after a decade living among the traps.

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Kea were known to use tools in captivity but this behaviour had not been seen in the wild until 2014, when then-Canterbury University student Mat Goodman captured it on film.

MAT GOODMAN A kea uses a stick to try open a stoat trap in the Murchison Mountains, Fiordland.

"For them to learn it quite quickly from an evolutionary point of view, it's really incredible," Goodman said on Monday.

"You start to see your place well within the other animals around you ... It proves to me anyway that looking at something from the perspective of what we know is not the end of the story."

Goodman's footage showed a single kea meddling with the trap, collecting and testing sticks until it found one that set the trap off. It also appeared the bird was whittling the sticks by pulling off twigs before testing them.

It did not necessarily want the food inside the trap, he said.

"It seemed to know and have this recognition that after it had set off the trap off that its job was done."

It took Goodman, who was doing contract work for the Department of Conservation (DOC) at the time, two-and-a-half years' filming to capture what DOC had suspected was happening.

The kea on the mountains treated four of Goodman's cameras like they treat many cars: "The memory cards were always gone," he said.

He sent the footage to former Auckland University psychologist Dr Gavin Hunt, who spent 16 years studying New Caledonian crows.

Hunt said the many years it took for kea to learn to use tools, and the lack of the stick technique outside of the Murchison Mountains, indicated the process was "cognitively demanding".

Kea "might have a higher level of intelligence" than the New Caledonian crow, whose plier-shaped beak naturally lends itself to tool use.

"The kea might be the only non-tool user that we know of to invent [this] repeated habitual behaviour in the wild, so it's quite special in that way," Hunt said.

"It would be neat for kea now to use tools in a natural setting; that would confirm our assumption that there are opportunities for them [to learn more]."

The traps provided a "modified environment", but it was possible kea might start using tools to forage for insects, Hunt said.

Having undertaken his work without funding, Goodman hoped further research would indicate whether kea use tools in their natural environments.

It had been "amazing" to see the effort the kea put into opening the trap, and there was likely more to learn about the species' behaviour in the wild, he said.