The centuries old grudge match between South Island sheep farmers and bloodthirsty mountain parrots could soon be over.

Researchers say early trials of a nauseating spray-on bird repellent, applied to high-country sheep to dissuade kea from tearing holes in their guts, have been highly promising, and they are seeking partners for further research.

Tamsin Orr-Walker, co-founder of the Kea Conservation Trust, said from the late 1800s high-country sheep farmers waged war with kea, because the inquisitive parrots found that by pecking holes near a sheep's kidneys they could tuck into the tasty fat beneath.

Some 150,000 kea were killed after a bounty was placed on them in the 19th century. Kea have been a protected species only since 1986, and there are only 1000-5000 alive.

Orr-Walker said some farmers still reported losing up to 400 sheep a year to kea-strike.

Some sheep died of injuries, but far more died of blood poisoning from the kea's dirty talons. Merino sheep are especially vulnerable as they stand still when attacked.

The kea-repellent trials are being conducted by the trust with the Department of Conservation (DOC), Auckland's Unitec and an Otago farmer, and, if successful, could help reduce the perception of the birds as pests.

Orr-Walker said there were rumours of people "taking matters into their own hands and doing poisoning exercises on their properties", but this was impossible to prove.

She said the trials were "a major step forward in solving what has historically been a controversial and difficult conservation issue".

In late May, 203 sheep out of a flock of 337 were sprayed with anthraquinone - a chemical that leaves birds feeling queasy - mixed with lanolin to make it stick.

After 34 days in the open, a few of the treated sheep had mild injuries from kea, "but they were pretty much left alone", said Orr-Walker. However, an unsprayed flock nearby was badly hit, and some died.

"We can't yet say that the kea tried the flock up the hill, found something wrong with it, then went down to the one below," said Orr-Walker, "but potentially [that's what happened]."

She said the researchers wanted to continue trials over winter, and hoped more farmers might help. Future tests were planned using a different chemical, d-pulegone and a soya-based wax.

Orr-Walker said the trust had approached Federated Farmers about the research but had not received a response. She also planned to invite merino-garment manufacturer Icebreaker to get involved. "We've got dolphin-friendly tuna. How about kea-friendly merino?"

Federated Farmers president Bruce Wills told the Sunday Star-Times he'd not heard of the kea-repellent research, but "if it's a genuine study that's going to come up with some genuine results, we're always happy to get involved where it's going to be beneficial".

Jonathan Wallis, co-owner of Minaret Station in Wanaka, said kea strike was far less of a problem to farmers than in the past because there were fewer pure-breed merino and fewer sheep being left on remote grazing country. "But there are still farms that have significant issues with kea."

He said since the 1970s farmers had become “acutely aware of the national interest in indigenous wildlife”, and he was not aware of any "vigilante" approach to kea by farmers.

Orr-Walker said humans weren't the only threat. Some kea got lead poisoning from eating the flashing off buildings, chicks got eaten by stoats and possums, and others died after eating the 1080 designed to kill those very predators (though trials of bird repellent in the pellets have been promising).

She said the kea's intelligence was "astounding".

"I think we're very lucky to have them, even though they can be very annoying."

- © Fairfax NZ News