Three yellow-eyed penguin killed, likely by stoats

Stoats, ferrets or weasels have taken their toll on penguins - these rescued chicks are now at Penguin Rescue's rehabilitation centre. Photo / Otago Daily Times

Almost all of this year's yellow-eyed penguin chicks at a South Island colony have been taken in to care after three were killed, likely by stoats.

Forty-eight of 49 chicks born at the two Moeraki colonies are in the care of Penguin Rescue, after staff decided intervention was the only way to keep them safe.

Penguin Rescue manager Rosalie Goldsworthy said staff last month found corpses of the world's rarest penguins that appeared to have been killed by mustelids — stoats, ferrets or weasels.

Previously, she had seen vulnerable chicks killed by rats, but these dead birds were 2 months old and weighed 3kg, she said.

Five chicks were found to be missing from their nests at the colonies, at or near Katiki Pt, in late December, and although two were later found alive, three were dead.

"The animal that's been killing them took a bite out of their necks — didn't eat them, wasn't hungry, but that killing instinct was in their bones.

"They were big birds and the [predator] dragged them away from their parents and just left them."

Moeraki's 38 nests — experts fear the birds could be on the brink of extinction from mainland New Zealand — had produced 49 living chicks this year.

The birds were now at the rehabilitation centre in a specially designed pen, where they were fed fish twice daily by hand.

"We had a dilemma. We got in a predator control expert who said that all of our [pest control] efforts were excellent, but there are no guarantees."

As the birds were now "post-guard", a stage of the breeding cycle when they were large enough for both parents to leave the nest in search for food during the day, the only way to keep the young ones safe was to intervene, she said.

The one chick that remained in the wild on the peninsula hatched late and was still being cared for all the time by one of its parents.

After the deaths, Penguin Rescue had altered some of its trapping strategy, a hunter from the local runanga had engaged a motion-sensing camera, and they had since caught three ferrets.

Yellow-eyed Penguin Trust science adviser Dr Trudi Webster agreed that predation of this kind was "quite unusual" but she too believed the deaths were likely the work of a mustelid as the predator had "grabbed the back of the neck" of the young birds.

The chicks' bodies have been sent for autopsy.