By Samantha Gee/RNZ
A generous investment in the country's smallest national park has seen whio, pateke and kaka reintroduced into the Abel Tasman, with gorse and wilding pines also removed from the landscape.
They are just some of the gains in the country's first large-scale conservation partnership, Project Janszoon, which is coming to an end after 14 years of work and more than $21 million in investment.
Nelson couple Marion and Bill Gilbertson are among the many project volunteers who have spent years removing weeds from the park.
"I remember our very first trip as teenagers along this coastline, as you walked on the beaches to one side was just walls of gorse," Marion Gilbertson said.
Now along parts of the coastline, it is hard to find any evidence of the spiky shrubs.
"The same way that you get used to seeing weeds on our foreshore, we got used to there being no birdsong, so we just expected there wasn't any and now we are hearing it and seeing robins and pīwakawaka and kaka," Marion Gilbertson said.
"You realise that over time and with a lot of infrastructure and money and support, you can turn an entire park around, that's just mind-blowing."
Bill Gilbertson said it would not have been possible without the philanthropic investment and a willing workforce of volunteers.
"It's the only way the conservation estate like this can survive."
A bold vision for large-scale restoration
Project Janszoon was established in 2012, and since then a trapping network has been extended across 90 percent of the park with tens of thousands of pests wiped out, wilding pines and other weeds have been removed, native birds reintroduced and lowland forest restored.
The conservation trust set out with the bold vision of restoring the park's ecosystems, made possible by funding from anonymous donors who were later identified as Auckland couple Neal and Annette Plowman.
It worked alongside the Department of Conservation (DOC), the Abel Tasman Birdsong Trust and iwi to make that happen.
The couple made their fortune from a laundry business, founded in 1910 by Neal's grandfather George Plowman, that became New Zealand Towel Services and was sold to American company Alsco in 1998.
They established the NEXT Foundation in 2014, with a $100m fund to go towards environmental and educational projects. In 2025, it announced another $150m would be invested entirely in the environment.
The Abel Tasman restoration inspired other landscape scale restoration projects, with NEXT going on to fund Taranaki Mounga, Predator Free Wellington, Predator Free South Westland, Zero Invasive Predators and Te Manahuna Aoraki.
The idea to focus on the Abel Tasman came from Nelson man Devon McLean. He had worked with the Plowmans on the restoration of Rotoroa Island, converting a privately owned working farm on the 83 hectare island in the Hauraki Gulf into an ecological destination.
"Neal said to me one afternoon, 'well, that was fun, what are we going to do next?' and I said, 'well, I've always wanted to fix the Abel Tasman, so why don't we go to an iconic national park, to the other end of the spectrum and see what philanthropy can do?"
It was a significant increase in size at 22,500 hectares, but that did not bother McLean, who had spent three decades in the forest industry and was a former chief operating officer for Carter Holt Harvey.
"I ran 450,000 hectares of plantations, so scale wasn't the problem. It was working out what are the real issues in here? And we spent quite a lot of time trying to figure that out."
He said the park was on a deteriorating parth. The bird life was not strong, there were species that had disappeared, the weeds were out of control and the wilding conifers were rapidly increasing in numbers.
"Our starting point was really stop the negative influences, restore by bringing back some of the species, plants and birds that were missing, and future-proof the thing."
At the time, there were no other conservation partnerships working at such scale.
Martin Rodd, who is now a regional director for the Department of Conservation, but was then an area manager responsible for the Abel Tasman National Park, remembers McLean coming into his office with a bold vision.
"I just grabbed the management plan off the shelf and said, 'here's the two key challenges for this place, plants, and animals, all these introduced things."
Rodd said McLean came back and said: "I think we can do it... I've got some people I think you should meet."
"I remember looking at the scale of the program and writing down, this is about 40-fold increase in terms of management intervention of this place when we added it all up."
The initial plan was to set up an endowment fund to support the conservation gains into the future, but McLean said the trust decided that wasn't the best use of its money, instead agreeing to deliver ecological targets, with the government to take on responsibility for upholding them.
Project Janszoon and the Crown signed the Tomorrow Accord in 2014, with the Department of Conservation committed to maintaining the biodiversity gains in the park.
Rodd admitted the prospect was daunting.
"I feel the accountability of taking on the maintenance of these incredible outcomes. There are species like kaka for example, that they're there now and they were long lost from the park, we don't want to lose them.
"So the pressure's on, we're also in increasingly hard climatic conditions and we've got all these challenges around us, but it's so worth taking on."
Project Janszoon science advisor and operations manager Ruth Bollongino said the national park was a famous place with beautiful beaches, but it was not known for its ecological values 14 years ago.
"There were a number of native bird species that got lost, whio, kaka, pateke or brown teal and we wanted to bring those back, which we have. But there were also some native species that are rat sensitive, like robins, brown creeper and riflemen that are still present in the park but they were limited to the higher elevation areas and our goal was to allow them to come down to the sea again."
Bollongino said every time she visits the park, she sees more birdlife and regeneration of the native bush.
There are regular reports of robin near the coast at Anchorage, pateke swimming in the Wainui Inlet and kaka waking people in Bark Bay.
"We have done the heavy lifting like putting in all the trap lines, getting the pest numbers down and bringing back the native bird life.
"We have reached these targets that both sides agreed upon and now it's time for us to step back and time for DOC to take on the project and maintain this for the future and keep the momentum going."
The trust officially hands over the reigns to DOC and manawhenua on 30 June.
Abel Tasman National Park visitors asked to report sightings of toutouwai/bush robin
Toutouwai are flying high at Abel Tasman
'A real win for biodiversity' - Endangered whio set free
From 'functionally extinct' to thriving: How the South Island kākā made a comeback in Abel Tasman National Park
Kāka chicks boost Abel Tasman population
This story was first published on rnz.co.nz
