Conservationists believe they are close to defining the ideal formula for re-introducing kiwi to wilderness areas where existing populations have been greatly reduced or eliminated by predators. Last month (February) Hawke’s Bay-based Forest Lifeforce Restoration Trust succeeded in returning target kiwi numbers to a second large tract of land under its management.

This is thought by the Trust to be the first time that a single organisation has brought two kiwi populations back from the brink of extinction over a sustained period. And in such numbers that each population is now large enough to grow meaningfully and increase naturally with predator control in place.

The feat has been described by the national charity Save the Kiwi as “hugely significant” in the ongoing battle to save the Eastern Brown kiwi, the least managed and fastest declining of the North Island’s four regional kiwi populations.

“Re-introducing kiwi to any given rohe is not as simple as releasing juvenile kiwi into a forest and letting them get on with it,” said Save the Kiwi chief executive Michelle Impey. “It’s a carefully timed and implemented process of ongoing land preparation and ‘site readiness’, egg retrieval and incubation, genetic considerations, partnerships and stewardship, population density management, reintroductions and ongoing husbandry.

“The Forest Lifeforce Restoration Trust's ability to bring back kiwi populations at scale on not just one but two separate properties is proof-positive that when all these elements come together well, kiwi populations can thrive.

“In essence, this is the formula for returning our national icon back to the bush in a way that is successful and repeatable.”

Since its formation just 16 years ago the Trust has become one of the most prolific contributors to Operation Nest Egg, the nationwide kiwi recovery initiative that removes kiwi eggs from their burrows, incubates them and cares for the chicks in captivity until they’re big enough to fend for themselves in the wild. Through this effort it created in 2017, at its property in the Maungataniwha Native Forest in central Hawke’s Bay, a kiwi population that is now large enough to grow meaningfully and increase naturally with predator control in place.

A young kiwi chick was found recently at Maungataniwha, indicating that the birds there are benefiting from predator control work and breeding successfully.

Since 2019 the Trust has since been using juveniles sourced as eggs from Maungataniwha to re-establish a viable kiwi population on its neighbouring property, Pohokura. At that stage there was a remnant population of “a handful” of birds on the 11,400 ha property and the Trust said it wanted to introduce at least 200 kiwi by 2024.

That target was reached last month (February), a year earlier than planned, with the release of two male birds, Butch and Poi. They became the 199th and 200th Maungataniwha kiwi to be homed at Pohokura.

Trust kiwi conservation specialist Tamsin Ward-Smith said the kiwi population at Pohokura is not yet at the same density as the Maungataniwha population, partly because there was a smaller number of original birds for them to mingle with. But it was “definitely” now large enough, with a much-improved genetic mix, to grow meaningfully and naturally with predator control in place.

The Trust monitored 18 juvenile kiwi released at Pohokura for a total of 3,668 days, averaging 204 days per bird. Surprisingly, all of them appear to have survived the monitoring period although some moved beyond monitoring range and into neighbouring forests where there are similar levels of predator control.

“This was a first in my experience,” Ms Ward-Smith said. “We have taken it as proof of concept and it gives us huge confidence in the process we are following. We now know that if kiwi conservationists adopt this formula they’re going to get a viable, surviving and thriving kiwi population out the other end.”

Both Maungataniwha and Pohokura Forests have received aerial 1080 control operations on a regular basis.

“Overlay this with an effective mustelid trapping programme and intensive Operation Nest Egg work and you will get a viable, surviving and thriving kiwi population out the other end; one that can help populate other forests,” Ms Ward-Smith said.

“FLRT has thrown everything at this work and it’s reassuring to see the results. Reaching the 200 target for Pohokura is a huge milestone – the more kiwi released, the more kiwi that will benefit from predator control, and the quicker the population will grow”.

The Trust will continue to stock Pohokura with kiwi from Maungataniwha. Chairman Simon Hall said the area could easily hold as many as 500 breeding pairs and that this month’s 200-bird milestone was “just the start”.

Genetic representation is an important consideration when it comes to repopulating land with kiwi. The Trust aims to grow still further the number of new males fitted with radio transmitters at Maungataniwha so that it can incubate their eggs and release their chicks at Pohokura, broadening the genetic spread there. It hopes also to work with other conservation initiatives to cross-populate and supplement sparse populations.

Pohokura lies to the north of State Highway 5 between Taupo and Napier and adjoins the privately-owned Ngatapa Station (9,515ha), the Whirinaki Te Pua-a-Tāne Conservation Park and the Waipunga Conservation Area. Together with the Trust’s other properties at Maungataniwha, these properties form a contiguous 100,000 ha swathe of the central North Island where kiwi conservation is a priority.

Mr Hall said Pohokura’s expanding kiwi population was already re-populating these neighbouring areas.

Large-scale, sustained pest control and predator eradication takes place throughout this area with the help of equipment and services donated by Hawke’s Bay Regional Council and specialist not-for-profit pest management provider OSPRI. More recently Save the Kiwi has directed Jobs for Nature funding towards the work on Pohokura, with trapper Mike Walker managing an operation spanning 9,000 hectares.

Re-establishing kiwi at Pohokura supports the long-term goal of the national Kiwi Recovery Plan; to reach 100,000 kiwi by 2030 through growing populations of all kiwi species by at least two percent a year, restoring them to their former distribution and maintaining their genetic diversity. Save the Kiwi’s Michelle Impey said the success of the Trust’s work with Eastern Brown kiwi had contributed significantly towards achieving the two percent target for this taxon.

Mr Hall said the Trust’s work with kiwi could not happen without the collaboration of its conservation partners, particularly the Cape Sanctuary, the National Kiwi Hatchery and its funder Ngāi Tahu, the Department of Conservation and Save The Kiwi, the only national charity dedicated to protecting the flightless national icon.

In addition to the Maungataniwha Kiwi Project the Trust runs a series of native flora and fauna regeneration projects. These include a drive to increase the wild-grown population of Kakabeak (Clianthus maximus), an extremely rare type of shrub, and the re-establishment of native plants and forest on 4,000 hectares currently, or until recently, under pine.

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