It's been nearly two years since New Zealand announced to the world we'd be free of pest predators by 2050. Are we any closer to winning the war? Jamie Morton reports.
It had been raining for weeks in Taranaki.
When the clouds finally cleared this week, the mountain's new cloak of white snow shone resplendent against a brilliant blue sky.
It was a good day for pictures.
It was a bad one for pests.
At the foot of the Pouakai Range, in the rainforest garden Pukeiti, the region's leaders came together to declare war on every rat, stoat and possum in more than 4500ha of farmland surrounding the national park.
A $47 million, five-year battle would clear one wedge of countryside after another.
Cleaned-out areas, the gathering was told, would be bolstered against reinfestation by a network of natural barriers, traps and remote sensors clever enough to alert smartphones every time a vermin was killed.
Here was the largest-yet project of its kind: a beachhead from which New Zealand could reclaim its wilderness from the scourge of predators.
It seemed fitting that Taranaki should be where the fight starts - its lofty peak symbolic of the hike ahead.
To understand its enormity is to understand the damage already done.
For millions of years, a plethora of plants and animals thrived in an Aotearoa dense, green and far removed from the rest of the world.
That all changed, of course, when the rest of the world came to Aotearoa.
It took just 800 years for humans and the wave of pests we brought with us - rats, stoats, deer, ferrets, possums, hedgehogs, weasels - to obliterate a third of the native birds that flourished among our forests and waterways.
Gone with them are three of seven frogs, at least a dozen invertebrates, a bat, and perhaps three known reptiles.
Even after the onslaught, New Zealand could still boast one of the highest rates of endemism in the world, but much of what we had left was in bad shape.
Among 1000 native species either threatened or at risk of extinction are 81 per cent of birds, 72 per cent of freshwater fish, 88 per cent of reptiles, 76 per cent of marine invertebrates and 39 per cent of vascular plants.
At the edge of the abyss are extremely rare birds like kakapo, whose numbers had dwindled to around 130, the fairy tern, now with fewer than a dozen breeding pairs, and Haast tokoeka kiwi, of which just 400 remain.
Less known, but just as close to extinction, are species like the Canterbury knobbed weevil, the Mokohinau stag beetle, Limestone cress and Chesterfield skink.
That New Zealand could somehow turn the tide on the devastation - let alone replenish our forests with noisy native birdsong - has often been considered an impossibility, and for good reason.
There are enough pests in our wild to lay waste to 26 million native birds every year.
Killing all of them meant covering 26 million hectares of mainland countryside.
New Zealand hadn't even been able to achieve a complete eradication on its 220 sizeable islands - and that war began half a century ago.
With the limited resources of a small nation, whose best tool for the job remained blanket 1080 poison drops, how could it be done?
Those fronting the effort have made a battle cry from a particular remark by one of our brightest minds, the late Sir Paul Callaghan.
"It's crazy, it's ambitious," the physicist told his last public lecture in 2012, "but I think it might be worth a shot."
Fast-forward to July 25, 2016, when former Prime Minister Sir John Key announced to reporters at Wellington's Zealandia that it wasn't just worth a shot, but a mission with a hard deadline: 2050.
And by 2025, New Zealand was to have reached towards four other big goals.
We would purge predators from a million more hectares - and show it could be done across at least 20,000ha without having to put fences up.
The campaign for our islands would be finally won.
And we would have a scientific "breakthrough" that could take at least one of the pests out of the picture.
Tasked with drawing in private investment and pin-pointing large pest control programmes was a new venture, Predator Free 2050, with the Government to throw in a dollar for every $2 contributed by businesses and charities.
What's happened since then?
Much of the work has been in mobilising: new appointments, new training programmes, a new strategic plan.
Across New Zealand, 45 landscape-scale projects like Taranaki's have applied to Predator Free 2050 for funding, all of them representing about 1.5 million ha of mainland.
Scientists have been given their own small war chest in the DoC-managed "Tools to Market" fund, for promising new weapons.
One project is developing a pre-made bait for aerial control, to be first trialled on stoats.
Another is an artificial long-life lure designed to attract rats over longer periods.
Then there was an army of community conservation groups setting traps, baiting stations, planting trees, and giving millions of hours of free labour.
"We reckon there some 200,000 New Zealanders who every year participate in some form of community conservation," Predator Free New Zealand chairman Sir Rob Fenwick said.
"On all fronts, there's been significant progress."
DoC itself received a much-needed shot in the arm in this year's Budget, receiving $181m over four years, and an extra $81.2m specifically for predator control.
That was enough for DoC to run sustained programmes over 1.8 million hectares - an area the size of Northland and Auckland combined, and which Fenwick's group has projected it can match, separately.
Conservation Minister Eugenie Sage said DoC had previously had to go "cap in hand" to the Government for one-off allocations to help beat back plagues that hit when flowering beech trees littered forest floors with fresh seed.
"The new funding means that for the first time DoC has secure ongoing funding for landscape scale control."
One top conservation scientist, the University of Auckland's Dr James Russell, expected the boost would be enough to take gains that had been made around the country and lock them in for good, ticking one of the first boxes of the 2050 plan.
"For the first time in a while, we'll be moving beyond triage, to preventative medicine."
Most importantly, Russell said, the new Government was being even more ambitious in their commitment to the programme.
"After two years the project still gets media attention locally and globally – it wasn't just a flash in the pan but something that really has momentum," he said.
"And finally, we're seeing even more ambitious projects commencing alongside a credible strategy."
He singled out the clearing of mammals from Auckland Island, possums from South Westland's Perth Valley, Hawke's Bay's Cape to City and the capital's Predator Free Wellington.
Manaaki Whenua-Landcare Research's Dr Andrea Byrom said while the cash injection was modest in the scheme of things, it was still a "huge signal".
"Personally, I'm very optimistic for DoC because the funding demonstrates to DoC staff that their work is important - we shouldn't under-estimate how much of an impact that will have on their enthusiasm to tackle big goals like Predator Free New Zealand."
Byrom was also buoyed by a wave of support from Kiwis.
A recent survey carried out by the Biological Heritage National Science Challenge, which Byrom directs, found 85 per cent agreed investment in pest control today would future generations, and around two-thirds were aware of the 2050 vision.
There was less support, however, for some of those next-generation technologies that we may have to turn to.
Just a third of the respondents, for instance, were comfortable with using "gene drives", in which a small piece of genetic information can be edited and then passed to future generations of pests, potentially leading to a single-sex population that would eventually disappear.
Kiwis appeared to better favour other genetic interventions like the Trojan Female Technique, which used DNA tweaking to render male offspring infertile, and species-selective toxins.
Byrom pointed out that the current best estimate for complete eradication using existing technology, over the 30 years to 2050, was around $9 billion - or about 5 per cent of GDP.
"So, it's not feasible for a small nation, even with international investment," she said.
"That means we need to control predators at much larger scales, yet for a fraction of the cost."
She believed the best approach was some sort of "self-disseminating" tool that could be shared from animal to animal, and, rather than just gene-editing solutions, there were a range of promising bio-technologies.
Alternatively, the country could use "non-disseminating" tools such as a species-selective toxin, which could be delivered within the next few years, but which still cost around the same as 1080 to roll out.
"So, we are back to the same issue that we need a very cheap tool that is socially-acceptable and can be applied for literally a few cents per hectare," she said.
"That is the reason people are considering self-disseminating biotechnologies such as gene editing."
Russell agreed New Zealand simply couldn't afford to lay traps or poison across every 25m of wilderness.
"Many of the advances in the past, and many more in to the future, will be incremental advances, such as more ingenious traps, more specific and humane toxins, and so on, and we shouldn't undervalue such advances," Russell said.
"However, we could short-cut this long incremental process which might take decades to scale to New Zealand, with a game-changing technological breakthrough, which would might put nationwide eradication in reach within years."
What needed to happen to make that a reality?
It was a tough question, but Byrom said being able to demonstrate success, and being up-front with the public, were part of the answer.
Lab-built "silver bullet" solutions also wouldn't do the job by themselves, but alongside those means already at our disposal.
It was entirely possible that one of the early objectives could be met through a more calculated approach to 1080 poison drops.
One partnership project dubbed Zero Invasive Predators had used this to obliterate all possums and rats across a 2300ha plot, and were this winter trying to replicate that success across 7500ha of South Westland bush.
But just as important as the science were the strategies built around it.
A new report commissioned by Predator Free New Zealand revealed a raft of problems facing conservation at grassroots level - namely that the impact of hundreds of volunteer groups wasn't being uniformly measured, nor being strategically funded.
That report's author, ecologist Dr Marie Brown, said "gappy" information about how our species and ecosystems were faring posed obvious headaches.
"I've already hinted at the need for better and more coherent collaboration between conservation players - preferably articulated in a strategic plan that is outcomes-focused and funded," Brown said.
"In addition, clever prioritisation of resources is also necessary, as is greater monitoring of the outcomes of conservation activity whether by community or agency."
The 2050 vision was a big goal, so tracking progress would be essential to maintaining investment - and public interest.
Sir Rob turned back to Callaghan's dream.
"He knew it wasn't possible without some breakthrough science. But he also knew the best incentive for deep pocket science investment is the dream of an outcome everyone buys into. He got this right."
No one he'd spoken to believe a predator-free New Zealand was a bad idea.
But it was a massive undertaking.
A mountain-sized one.
"We'll need every clever idea and every dollar of research investment, whether it's a gene edit technology or a new Wi-Fi technology enabling remote monitoring of traps or multi-kill trapping devices," he said.
"This was always going to be a long game. I don't think anyone thought that on 31 December 2050 there'd be a ceremonial beheading of the last rat in New Zealand.
"But there is every reason to be optimistic that by that date, New Zealand's magnificent unique biodiversity will be more prolific and abundant than it is today.
"I doubt many countries that boast that outcome with much confidence."
Our war on pests
26 million: a conservative estimate of the number of native birds slaughtered by pest predators each year.
81 per cent: the proportion of native birds now considered threatened. Among the most endangered are kakapo, Haast tokoeka kiwi, black robin and northern rock wren.
$9b: the estimated cost of clearing pest predators from 26 million hectares of New Zealand mainland, using existing tools, over 30 years.
45: large-scale projects that have applied to Predator Free 2050 for funding, representing about 1.5 million hectares of mainland.
61 per cent of respondents in a nationwide survey were aware of New Zealand's goal to become predator free by 2050.