Taranaki's great pest purge gives hope for NZ's 2050 mission

The first region to begin ridding itself of bird-killing pests has made promising progress – sending hope to conservationists battling toward a predator-free New Zealand.

Taranaki's bold bid, launched a year ago, ushered in a new era of landscape-scale operations, which would be crucial to clearing all 26 million ha of possums, rats and stoats by the middle of the century.

The region was also being looked upon as a testing ground, both for new tactics and technology, and for uniting community groups, iwi and people across town and country in the mission to tackle the country's biodiversity crisis.

More than three quarters of our native birds were either threatened or at risk of extinction, largely due to pests that killed some 26 million of them every year.

Towards Predator-Free Taranaki, the biggest project of its kind, would cost $47m in its first five years, with $11.7m coming from the Government.

David MacLeod, chairman of project leader Taranaki Regional Council, told the Herald that Taranaki had unique advantages because of its relatively compact geography.

"Its regional and national expertise in biodiversity and predator control, and strong community collaboration and enthusiasm at all levels, means its great testing ground," he said.

"From the work in Taranaki, lessons can be learned and shared with the rest of the country, helping remove rats, stoats and possums from urban, rural and conservation land."

The programme was designed to clear one wedge of countryside surrounding Mt Taranaki after another, eventually covering more than 4500ha of farmland.

Those cleaned-out areas 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.

The latest monitoring data showed intensive predator control may already be making a difference – rats and possum numbers in urban New Plymouth appeared to be dropping, while the trapping network in rural and urban areas was expanding rapidly.

Monitoring, using rat footprint tracking and a possum bite-mark index, shows catch rates have dropped; rats went from 33 per cent to 19 per cent in the past year, while the urban New Plymouth possum index has fallen from 25.6 to 1.4 per cent in the past four years.

"It suggests the rapidly growing trapping network in urban New Plymouth backyards, parks and reserves is having an impact, supporting successful efforts removing predators on rural and conservation land," MacLeod said.

Other highlights in the past year included 53 possums being caught in seaside Oakura, and another 140 around its outskirts, within the past four months.

Students from 30 New Plymouth schools were analysing catches, checking traps on public land, making traps and selling traps to local residents as a fundraiser.

At the same time, the first North Island robin to be seen in 112 years at rainforest garden Pukeiti, where the programme was launched, was spotted after intensive predator control in the area.

Robin returned to Pukeiti, after being released following predator control on Egmont National Park by Taranaki Mounga Project.

New Plymouth rural landowners were beginning to manage and maintain traps using a new wireless trapping network and self-resetting traps, helping catch and monitor stoats, ferrets and weasels on a large scale, across 14,000ha between Egmont National Park and New Plymouth for the first time.

One of a range of smart traps now being used on Mt Taranaki as part of a new drive to eradicate pests. Photo / Alan Gibson

The project had initially focused on New Plymouth district in the first year, before expanding around the mountain in the coming years, but demand by residents to get traps in backyards has, at times, stretched the supply of traps.

"Trap catches may slow down soon, but that's when we know predator numbers are decreasing and we need more traps operating, strengthening the trapping network before it expands further around the region," MacLeod said.

'Aotearoa writ small'

University of Auckland conservation biologist Associate Professor James Russell has been watching the project with interest.

"It appears to have all the necessary components for becoming predator free coming in to alignment: the technology is there, the community support it, and its geography makes it possible," Russell said.

"In this regard, it's really Aotearoa writ small – and when we break down Predator Free New Zealand in to bite size chunks, it begins to become clear how the pieces of the puzzle can be put together to make all of New Zealand possum, and then rat and stoat, free."

Elsewhere, five large landscape-sized projects with funding from Predator Free 2050 – which received $1 from the Government for every $2 contributed by businesses and charities - were now under way.

"In total we have around 51,000ha where we are looking to prove we can remove predators and protect from reinvasion," Predator Free 2050 chief executive Ed Chignell said.

Wellington's 1000ha Miramar Peninsula would look to achieve that for rats and mustelids in July.

At Perth Valley on the West Coast, an operation had begun to wipe out possums and rats across 12,000ha, while a three-year programme across 14,500ha of Hawke's Bay's Mahia Peninsula would target possums.

Otago Peninsula's 9000ha possum eradication operation is also well down the planning track and due to begin in December.

"Waiheke now has an operational team in place to start its planning and community consultation to remove stoats and rats beginning early next year," Chignell said.

The Te Manahuna Aoraki programme, led by the Department of Conservation and Ngai Tahu, aimed to make 310,000ha of the South Island's Mackenzie Basin predator-free.

There had also been huge interest in Predator Free NZ's Products to Project fund for innovating new pest control products and technology.

The company had received more than 60 expressions of interest for the Government-created company's available research and development funding.

Some funding would go directly to the Zero Invasive Predators to help deliver the new traps, lure dispensers, nodes, software and satellite communication devices that the company had in development.

Conservation Minister Eugenie Sage said the public backing for Taranaki's project was "very encouraging".

"It's just one example of the upsurge in community interest in protecting our forests and wildlife from insects to birds from predators and people taking action to do that," Sage said.

Conservation Minister Eugenie Sage, pictured at the project's launch last year, was encouraged by the latest results. Photo / Alan Gibson

"Auckland had a Pestival last year bringing together many of the community groups doing trapping, scientists and agencies involved in predator control and wildlife conservation.
That's an initiative which we are likely to see elsewhere."

One recent survey 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 will likely be needed to achieve it.

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.

The current best estimate for complete eradication using existing technology, over the 30 years to 2050, was around $9b - or about 5 per cent of GDP – which was arguably unfeasible for a small nation.

Predator Free 2050 chairman Sir Rob Fenwick has called for New Zealand to have a national discussion about genetic technology.

Sage has ruled out Predator Free 2050 investing in research into genetically modified organisms and technologies, earlier telling the Herald that a "great deal of research and understanding, as well as public acceptance, is required before such technologies could be implemented".

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.