New Zealand's heaviest insect has been taking big steps toward a population boom, with the success of a ground-breaking breeding and conservation programme.
Wētāpunga - or Little Barrier giant wētā, used to be widespread in Northland and Auckland, but by the 1990s only one remnant population remained, and only in one place - Little Barrier Island, the Department of Conservation says.
That population was found to be dwindling and in bad shape when surveys were carried out, from 2005 to 2009, and it was decided there were too few of the wētāpunga left to directly start another wild colony to be able to safeguard the species.
So instead, small numbers of the giant insects were collected from Little Barrier Island, to begin an intensive breeding population.
Tens of thousands of wētā have now been bred at Butterfly Creek in Auckland and at Auckland Zoo.
The efforts mean the ancient insect has gone from being classed as a Nationally Endangered species in 2004, to Nationally Recovering.
And details of the project to save the endemic species have just been published in the New Zealand Journal of Zoology.
Lead author Dr Chris Green says last year the success of the project meant 11,000 wētāpunga could be released onto predator free islands and into fenced sanctuaries, to finally establish more wild populations. He expects their population will keep growing.
"Of all our giant wētā, this is the largest, species, the size of adult females would sit nicely on the entirety of your hand - so they're a very big insect," he said.
"This species was endangered at the start of the programme, it is now not endangered - it is recovering. So that is a significant benefit to the species and New Zealand's biodiversity.
"We need to do that with a lot more species."
Workers at Butterfly Creek, a small zoo in Manukau, developed early knowledge about breeding the wētāpunga and releasing them. And that was "refined and industrialised" by the Auckland Zoo team, who were able to rear large numbers of wētā in communal creches.
The project has been "one of the most comprehensive case studies of invertebrate conservation breeding, translocation and species recovery ever undertaken in Aotearoa New Zealand, Green said, with significant expertise and commitment from many hands-on conservationists working with the wētāpunga.
Iwi Ngāti Manuhiri - the mana whenua of Te Hauturu-o-Toi Little Barrier Island, where the founding wētāpunga used in the project came from - also supported the efforts, and many community groups fundraised to pay for the programme, and support the releases and ongoing monitoring of the wētā populations.
"By documenting this amazing conservation success story, we can share valuable knowledge on husbandry, release methods, and population persistence," Green said.
"The future of wētāpunga is looking bright. What we have learnt is now informing breeding of Māhoenui giant wētā at the Ōtorohanga Kiwi House.
"There are many more critically endangered invertebrates that could benefit from similar programmes, for example the Canterbury knobbled weevil (Hadramphus tuberculatus) and several native stag beetle species."
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