How to stop some of the famously curious alpine parrots eating 1080 cereal baits deployed to kill their predators has been a headache facing conservationists.
Studies have shown that kea that live close to areas where they can scrounge food from people are at much higher risk of being poisoned than birds in remote areas, where cases of 1080-related deaths are also offset by the protection that 1080 drops give them during nesting.
Even so, scientists have been working to remove as much as that unintended risk as possible – and have now explored whether kea could effectively be trained to avoid the pellets, by feeding them "mimic" bait designed to put them off.
The concept had its roots in a project run by Department of Conservation-founded Zero Invasive Predators (ZIP) in South Westland's Perth Valley, where new ground technology and 1080 operations have helped wipe out nearly all local rats, possums and stoats.
"The project area is within kea habitat, so ZIP began researching ways to reduce the risk of the operation itself harming the local population," ZIP predator ecologist Maggie Nichols said.
That included a proof-of-concept study looking at how attractive tahr carcasses were to kea – and more recently, whether using the anthraquinone, bird repellent that induces queasiness, could help train the birds away from bait.
Working with a team of researchers at Christchurch's Willowbank Wildlife reserve, Nichols pushed the idea further by trying to train captive kea to avoid non-toxic cereal baits that perfectly mimicked the look, feel, and taste of 1080 baits.
Each of the 10 kea in the study were hand-fed baits treated with 2.7 per cent anthraquinone, in trials using two different types of cereal baits often used in aerial drops.
By the end of the trial, just one took up the offer to snack on the pellet. By the end of another test run, this time with nine kea, only one bird ended up eating enough bait to a level that would have been fatal with toxic bait.
The aversion effect they created continued even when baits were offered a further six times over two days.
Nichols said she and her colleagues – among them, prominent University of Auckland animal psychologist Dr Alex Taylor, were surprised at the birds' response, which even included kea throwing baits back at them.
"This study opens up the possibility of training at-risk individual kea to avoid toxic cereal bait after multiple feeding events."
But she added that the captive birds were also presumably easier to expose to aversion baits than their wide-ranging wild counterparts.
"Furthermore, anthraquinone can make mammals averse too, so providing aversion baits to kea, while restricting access by possums and rats, could present challenges for some operations."
The insights, detailed in the journal Applied Animal Behaviour Science, comes after a series of new studies transforming what we know about kea.
This year, a study led by Taylor found the parrots can make predictions using statistical, physical and social information in a similar way a human would.
Other research has found they're not only clever problem-solvers, but are happy to team up on tasks, even when the reward isn't shared equally - and that they're likely little different from a human infant, learning about their world by interacting with objects around them.
Although the nationally-endangered species is seen in reasonable numbers throughout the South Island, the true size of the wild population is unknown, and estimated at between just 1000 and 5000 birds.