Giant wētā: Success for new breeding programme, after decades-long drought

This wētā being held by Ōtorohanga Kiwi House wildlife manager Mathew Ronaldson is an adult female. Photo / Libby Kirkby-McLeod, RNZ

By Libby Kirkby-McLeod of RNZ

For the first time in decades, the critically threatened Mahoenui giant wētā has been bred in captivity, at a new centre especially set up for the task.

The wētā are among the world’s largest insects, and are unique to the Waikato, target="_blank">King Country.

The zoo laboratory at Ōtorohanga Kiwi House was initially designed using captive rearing protocols for other wētāpunga, but staff soon discovered the local wētā had its own idea about what makes a dream home.

Ōtorohanga Kiwi House wildlife manager Mathew Ronaldson said when Mahoenui giant wētā were first bought to the zoo, staff noticed that the females weren’t keen to lay eggs.

They would poke around in the volcanic soil, which is the kind used for other giant wētā breeding programmes, but they didn’t seem to like it.

A Mahoenui giant wētā at the Ōtorohanga lab Photo / Libby Kirkby-McLeod, RNZ

It was the first sign that Mahoenui giant wētā might have their own home decorating tastes.

The wētā are found in the wild at the Department of Conservation Mahoenui Scientific Reserve, southwest of Te Kūiti.

“We looked at Mahoenui itself, but we couldn’t actually use that soil, so we looked around for areas that were a similar climate, similar environments,” Ronaldson said.

Staff needed chemical free soil from a location with a similar altitude, humidity, and soil structure as Mahoenui and found it on a farm in Waitomo.

The family who own the farm was happy to share, so the team went and dug up some soil.

“And it actually has worked. They do prefer that, its much nicer on their ovipositor and of course it is similar to Mahoenui reserve,” Ronaldson said.

Other wētāpunga have been breed in captive rearing programmes at Wellington Zoo, Butterfly Creek in south Auckland, and Auckland Zoo.

But Mahoenui giant wētā have not been successfully reared since the 1990s, and the wild remnant population is hanging on to survival, with monitoring of wētā in the Mahoenui Scientific Reserve showing numbers have been declining since 2013.

The team at Ōtorohanga Kiwi House needed to work hard, changing one variable at a time, until the wētā were set up for success.

Senior wildlife keeper Carly Hill said they have been waiting for eggs to hatch since 2021.

“We were all quite a bit excited by the time we realised we’d actually done it - there might have been some dancing and some jumping and some shouting going on,” she said.

Ōtorohanga Kiwi House wildlife manager Mathew Ronaldson looking into one of the lab's larger habitats, where they put pairs for breeding. Photo / Libby Kirkby-McLeod, RNZ

General manager Jo Russell had a similar reaction.

“I’ll admit to some joyous jumping up and down and excitement [when] the team called me,” said Russell.

The Kiwi House now has 120 young wētā, and a second group of adults are breeding and laying eggs.

It aims to breed 3000 Mahoenui giant wētā for release into a local predator- free sanctuary.

Hill said she hoped she could be with the wētā through the whole journey.

“It will be sad to see them go as obviously they are our very first babies, but it will be nice to see them actually go into the wild,” she said.

The Kiwi House now have 120 young wētā, and a second group of adults are breeding and laying eggs. Photo / Libby Kirkby-McLeod, RNZ

The new facilities which have allowed for the wētā breeding laboratories are part of a larger redevelopment project underway at Ōtorohanga Kiwi House, funded by a low-interest loan from the local council, and grants from the previous government’s shovel-ready funding, and the Ōtorohanga charitable trust.

Kiwi House development manager Julian Phillips said it is working towards becoming the world’s first ‘Living Community Challenge’ accredited zoo.

This accreditation programme recognises the highest standard of socially just, culturally rich, and ecologically restorative building in the world at present.

All materials used in the construction of the wētā laboratory for example are recycled, natural, or red-list chemical free.

The lab contains different habitats for the grown wētā (above), and layers of habitats for the hatched wētā (below). Photo / Libby Kirkby-McLeod, RNZ

“It’s building with safe materials at the end of the day,” said Phillips.

He believes that the zoo laboratory set up for the wētā breeding habitat can be replicated anywhere in the country and can help conservation move away from using old shipping containers.

“They’re just not very nice. They sweat, it’s really hard to [make] them perform sustainably ... it’s not just about the humans, its about our wildlife, they can’t tell us if they are unwell from breathing things they shouldn’t be,” Phillips said.

For those interested in seeing the Mahoenui giant wētā, Ōtorohanga Kiwi House said they are hoping to soon start guided tours to view the wētā laboratories.

- RNZ