Two furry friends delivered the welcome news recently that Orokonui Ecosanctuary was predator-free, after surveying the area for two days.
About five weeks ago, fox terrier Tussock and fox terrier-Jack Russell-cross Macca had indicated there was a predator on the grounds.
The dogs are trained to sniff out mustelids, which include weasels, stoats and ferrets.
"It was a very stressful time," ecosanctuary conservation manager Elton Smith said.
"I lived through 2015, when a stoat got into the ecosanctuary, and that was ghastly.
"You are just waiting for your phone to go off and hear the bad news."
Staff acted quickly, baiting about 2500 traps with rabbit meat and poisoning mice in the hope the culprit would feed on the rodents and receive secondary poisoning.
The indication from the four-legged ferret finders, last week, that the culprit was gone was a "massive relief", Mr Smith said.
Tussock, who is nearly 2, was one of the conservation dogs involved.
He was a certified by the Department of Conservation’s Conservation Dogs Programme about six months ago, after spending his whole life training for it.
Handler Alex Ghaemagham said teaching Tussock to sniff out mustelids took many hours of ongoing training, even after certification was given.
"You still spend a lot of time keeping them interested and current ... they need lots of training.
"He is the nose and I am the interpreter."
The most important part of training was to ensure the dogs were not interested in the wrong animals, she said.
"We need to make sure the dog is safe around them ... all of our dogs do wear muzzles when working around ground birds, just as an extra precaution."
Macca, who is about 6, and his handler and Doc senior ranger Angela Newport were the other team who surveyed Orokonui.
They were also involved in indicating the stoat incursion at the ecosanctuary in 2015.
Mr Smith said conservation dogs were the best way to monitor stoats and once the dogs indicated the presence of a predator, nothing else mattered but ensuring it was removed, he said.
