The 'extraordinary' intellect of the kea has surpassed researchers' expectations following the discovery that they used tools to set off stoat traps.
The research published on Monday was sparked by a 2014 video, which captured a wild kea using sticks to set off the traps in Fiordland's Murchison Mountains.
The alpine parrot's either carefully crafted the stick to the exact size to probe the lock, or completely reshaped the stick itself.
The research states this is the first documented case of habitual tool use innovated in the wild by a bird species only known to have used tools in captivity.
Over two and half years, sticks were found inserted in 227 different traps.
"They carefully select certain sized sticks, whittle them down or select a new one, selecting the right size tool or reshaping it to be the right size," field researcher Matthew Goodman says.
He says kea get a "buzz" from the noise of setting the trap off.
"From what I witnessed, is that they certainly get a buzz from loud noise or when they throw something off the cliff or steal something and get a reaction.
"They seem to really thrive with that. [It's] very parallel to what children do, they do something naughty - it's almost the same thing at least you can interpret that way."
And he hopes the research will spark more interest in the species.
"Hopefully [it] sparks some more research into their intelligence, it opens the door of studying these birds and elevating them on the world stage of birds and mammals."
The research was taken in conjunction with Auckland University psychologist Dr Gavin Hunt and Thomas Hayward.