A native bird famous for its mischievious behaviour has now figured out how to use tools, researchers have found.
Researchers have found that world's only alpine parrot - the kea - in the South Island's Murchison Mountains is using sticks to get food out of stoat trap boxes.
The findings by Gavin Hunt and Mat Goodman have been printed in the Scientific Reports Journal.
The pair found that over a 30-month period, 227 different traps had been raided using sticks across the ranges, which indicated many kea were responsible.
The trapping is part of a Department of Conservation operation to protect Takahe.
From 2002 to 2009 the traps were untouched, but then trappers began to notice the boxes tipped upside down. Some had stones in them and a growing number had sticks in them.
"It's an incredible amount of tool-using," Mr Hunt, an ecologist, said.
Trail cameras were set up and filmed a kea probing a trap-box with sticks.
It is the first evidence of non-humans using a tool in the country.
Mr Hunt said it would have taken many years for kea to develop the technique.
"It seems to be unique... a non-tool using bird having such extensive tool using behaviour and repeatedly using tools over many years."
"It shows the kea has high general intelligence to invent the tool use and keep using the tools to get the eggs out of the trap-boxes."
This suggests how cognitively demanding its been for the birds to figure out the technique, which shows its intelligence, he said.
It may be more difficult to invent tool use in the wild because the natural food is better hidden and more demanding to find, he said.
Having a situation where the food is sitting in a box and easier to see and reach could have encouraged the birds to invent the tool, the research suggests.
Kea are known to have used tools while in captivity but not in the wild, Mr Hunt said.
He said this makes kea one of the better candidates for New Zealand's "smartest bird".
Further research is now needed to discover if kea can use the tool to hunt for legitimate sources of food in its natural environment, he said.