An iwi-led conservation project in the Kaimai Mamaku Forest has recorded zero rat activity across more than 700ha of native bush.

The result is wide-reaching in its benefits for native wildlife, in particular, the chances of a successful North Island kōkako breeding season.

The North Island kōkako is a native bird with slate-grey plumage and distinctive blue wattles under its beak, and is known to sing for over an hour, the longest duet of any songbird in the world.

But predation from introduced species, as well as deteriorating forest canopy quality, left this taonga on the verge of extinction at the turn of the century.

Its South Island cousin, distinguished by its orange wattles, is officially declared “data deficient” by the Department of Conservation, meaning no verified proof exists they are not extinct.

The North Island kokako has one of the world's longest singing duets. Photo / Richard Littauer

But for the North Island kōkako, numbers have grown from just over 300 remaining breeding pairs to more than 2000, thanks largely to conservation efforts.

The native species remains in the at-risk conservation category, however, and predator control is widely regarded as essential to maintaining its recovery.

Iwi-led conservation project Te Wao Nui o Tapuika has now achieved 0% rat tracking in an area of woodland between Ōtanewainuku, in the Western Bay of Plenty, and Kaharoa, north of Rotorua, following a two-month predator control operation in November 2025.

The result was supported by no rat prints being detected in tracking tunnels.

“Zero per cent is what everybody aims for, and you don’t get it very often,” Manaaki Kaimai Mamaku Trust chief executive Louise Saunders said.

The trust acts as the co-ordinating entity for the Kaimai Mamaku Restoration Project, which brings together eight iwi and hapū groups across the central North Island to help conservation efforts in the forest.

“For kōkako breeding, rats have to be under about 5% [detection in rat tracking] before the season starts.

Manaaki Kaimai Mamaku Trust chief executive Louise Saunders. Photo / Supplied

“Where rat indices are being well controlled, kōkako populations increase, and that’s why results like this matter.”

The Te Wao Nui o Tapuika project is part of the wider Kaimai Mamaku Restoration Project.

The Tapuika field team of two maintains a network of traps and bait stations across steep and remote terrain.

Te Taiao kaimahi (team member) Richie Emery said the result reflected sustained effort over time rather than a one-off intervention.

“We’re grateful we were able to make a big impact this year,” Emery said.

“Knowing we’ve given the manu [birds] and the ngahere [bush] a chance to thrive makes the work worthwhile.”

Workmate Rawiri Faulkner said the motivation went beyond employment.

“You’re giving back to te taiao [nature],” he said.

“I’m not doing it for me, I’m doing it for future generations.”

Te Taio Kaimahi Rawiri Faulkner at work in the Kaimai Mamaku Forest. Photo / Supplied

It is work that has been ongoing at a community level since 2009, Saunders said, with Manaaki Kaimai Mamaku Trust coming on board in 2019.

The Kaimai Mamaku Restoration Project began in 2020 with Jobs for Nature funding and is now supported through a mix of funding models.

The trust’s ongoing relationship with the Bay of Plenty Regional Council was integral to its success, Saunders said.

Council coastal catchments manager Charles Harley said it supported the project.

“Our monitoring shows these locally led efforts are making a real difference, with healthier forests and improved habitat for native species,” Harley said.

“Strong community action, backed by good data and long-term investment, is key.”

Climate change had also been a factor in predation rates on kōkako, with warmer winters decreasing predator mortality leading into the breeding season.

“People got us into this mess, and it will take people to get us out of it,” said Saunders.

“You can’t just lock up the forest and everything will be okay. It takes intervention and management to restore it.”

A 2023 census found 113 kōkako living within the Ōtanewainuku forest boundary - 51 pairs and 11 singles - which was an increase of 69 from 2020.

Saunders said the success of the current kōkako breeding season will not be known until next year, when numbers are surveyed again.

Mathew Nash is a Local Democracy Reporting journalist based at the Rotorua Daily Post. He has previously written for SunLive, been a regular contributor to RNZ and was a football reporter in the UK for eight years.

- LDR is local body journalism co-funded by RNZ and NZ On Air.