New Zealand's kea could be one business-savvy bird, new research suggests.
Auckland University biologist Dr Alex Taylor and his team are carrying out intelligence tests on the native mountain parrots to better understand how clever they are, as part of a broader study into how intelligence evolves.
Although the research is still in its early stages, Taylor said the kea had displayed a penchant for commerce.
"We wanted to see if they would trade tokens for food," he said.
"So they give you a stone and you give them some food to see if they would get an understanding of that kind of co-operation between a human and an animal.
"One of the researchers, PhD candidate Megan Heaney, did a few transfers backwards and forwards and, since then, every time the kea see her they run up with a stick or a stone and try to trade it."
Preliminary experiments also indicated kea were "fantastic" at so-called inhibitory control - the ability to delay behaviour until the conditions are right to get a better result.
"They could be quite similar to chimpanzees and elephants in their ability to inhibit doing a particular action and waiting until the situation is right before they act," Taylor said.
"I've not been working with them for long, [but] we're starting to get tantalising evidence that they're a particularly smart species."
Kea are famously curious and are well known for ripping up cars at the South Island's ski field carparks.
In 2013, a kea reportedly stole hundreds of dollars from a Scottish tourist's campervan at Arthur's Pass. And in 2009, a British tourist in Fiordland had his passport stolen by a kea from his bus.
Taylor is no stranger to working with feathered creatures.
He has been awarded the 2015 Prime Minister's MacDiarmid Emerging Scientist Prize for his ground-breaking research on the cognitive and problem-solving ability of birds, particularly New Caledonian crows.
A crow called 007 completed one of the most complicated tool-using courses created for an animal mind, designed to investigate the effect tools have on the evolution of intelligence.
"The New Caledonian crow is famous for its problem-solving ability but it is quite stand-offish and only engages in a problem it's interested in it," Taylor said.
"Kea are just fascinating because they are keen on exploring new objects and interacting with humans.
"This makes me wonder whether they might be even a level above the New Caledonian crow."
The MacDiarmid prize gives Taylor and his team a $150,000 research grant, a large portion of which will go towards the kea project.
"It's an amazing opportunity and I'm grateful to have received this award to help to understand this incredible native species."
Results from the research will be available next year.