While kea have long been known to prey on sheep in the high country, new research has looked at the impact of the attacks.
Photo: 123rf
Kea strikes - which happen when the parrot digs its beak into the wool, eating it, the fat and the flesh - have long been a costly problem for farmers.
Massey University PHD researcher Clio Reid found just 0.5 percent of sheep in five high country stations had signs of kea attack. The median length of the wounds on a sheep's back from kea strike was 6 centimetres.
"We looked at those stations specifically because they had a history of kea strike.... they gave us the best chance of finding injured sheep," she said.
Dr Reid said her findings suggested the kea strike rate was a lot lower than it used to be historically, partly because there were now less kea and less sheep in New Zealand and there were now more vaccinations for livestock.
Dr Reid said wounds caused by kea were quite distinctive and in some cases, could be fatal.
"They look like a predator has jumped on the back of the sheep and had a bit of a go at them" she said.
The sheep being preyed on were mature sheep, but Dr Reid was not was not surprised by their outsized prey, as there was evidence which suggested they used to attack Moa that were stuck in swamps.
"I didn't find any evidence that they were picking on first year lambs that were still with their mothers... They go for the bigger, presumably fatter sheep, so hoggets and older," she said.