The New Zealand Government’s announcement that it wants to make New Zealand predator-free by the middle of this century is exciting, aspirational – and very under-resourced. It’s also not possible with existing technology.
The Predator Free New Zealand (PFNZ) 2050 target, announced on 25 July by the Prime Minister and a supporting cast of Ministers, involves setting up a new public-private partnership company, to help fund regional large-scale predator eradication programmes.
Ship rats and brushtail possums are two of the biggest killers in the New Zealand forest. This exceptional shot shows a possum and a rat feeding side-by-side on thrush chicks. Photo: CC BY NC 3.0 NZ Nga Manu Images
It’s great to see Government taking this ambitious idea seriously, although you do have to ask why they’re giving money for this at the same time they are starving the Department of Conservation of funds.
That aside, predator-free is an idea that already has lots of community volunteers, as well as DOC rangers, out on the ground trapping and poisoning, all with the aim of saving our previous native biodiversity.
And some of this country’s greatest minds are already thinking up more effective ways of dealing with the pest problem.
Ship rats (Rattus rattus) occur in large numbers in New Zealand forests, and eat large numbers of native birds, chicks and eggs. This rat is tackling a kereru egg, undeterred by its large size Photo: CC BY NC 3.0 NZ Nga Manu Images
The focus will be on rats, possums and mustelids. But when we say rat, we mean three species of rats – ship, Norway and kiore - as well as mice. And there are weasels and ferrets as well as stoats. And let us not forget feral cats, which are often the elephantine feline in the room, although John Key acknowledged in his announcement that feral cats will be targeted.
That’s eight species that need to be controlled, and the order in which they are controlled is very important. We already know that if we remove possums from forest, then ship rat numbers increase – unintended consequences are a real risk.
The technology to eradicate eight species of mammals from New Zealand doesn’t yet exist. Good progress is being made in incrementally improving existing trapping technology, self-resetting traps have been developed, and species specific toxins, such as PAPP for stoats have been shown to work.
But what this ‘Apollo moonshot’ requires will be left-field break-through – gene drives, perhaps, or Trojan females that produce sterile sons.
Timeline and aims
DOC’s website lays out the following aims, which includes research as well as management:
‘2020 goals
Develop a collaborative predator control strategy.
Another 175,000 hectares in addition to the current 1 million hectares on conservation land and 7 million hectares led by OSPRI are under some form of control.
Five projects supported by PFNZ are making progress, and sharing lessons.
PFNZ and DOC will tackle larger scale operations.
Collaborative results will show social and economic benefits.
PFNZ will foster community participation in local predator control activities.
2025 goals
Increase by 1 million hectares the areas of New Zealand where predators are suppressed.
Demonstrate predator removal in areas of mainland New Zealand of 20,000 hectares.
Remove all mammalian predators from New Zealand’s offshore island nature reserves.
Develop science solutions that remove at least one small mammal predator from the New Zealand mainland.’
The size – and cost – of the problem
New Zealand’s land area is more than a quarter of a million square kilometres, and the Government is initially putting in $28 million over four years, although it has also said it will match private and Council input, putting in $1 for every $2 contributed.
By comparison, the Antipodes Island mouse eradication has just cost about $4 million to get rid of one species on a tiny island that is just 22 square kilometres in size.
Just last year James Russell, from the University of Auckland, and Andrea Byrom, from Landcare Research and Director of the Biological Heritage Challenge, published a paper saying that the cost of ridding New Zealand of predators over 50-years would be more than $9 billion. This makes $28 million seem more than a little inadequate.
The Royal Society of New Zealand produced an interesting position paper on Challenges for Pest Management in New Zealand that takes a wider look at agricultural pests and weeds, as well as vertebrate pests.
The key to successful predator eradications is getting support from local communities. So far it is proving difficult to achieve this, as proposed eradications on Lord Howe Island in Australia, and on Great Barrier and Stewart islands in New Zealand have shown.
Predator free on Our Changing World
Every night in forests around New Zealand ship rats kill and eat tens of thousands of native birds, such as this fantail. Scientists are developing smart lures based on rat urine that they hope will improve the ability of resetting traps to kill predatory rats. Photo: CC BY NC 3.0 NZ Nga Manu Images
We have produced many stories under the theme predator-free, and here is a selection of them, including stories about new technologies.
The Science of Predator-Free New Zealand with Andrea Byrom and James Russell
The 'pee' in pest control - developing super lures
'Trojan Females' - A Novel Idea for Pest Control
Stoat Toxin and the Spitfire Trap
Killing Rats With Self Setting Traps
Science Behind 1080 Use in Conservation
Innovation in Conservation: includes an award for developing an early response system for monitoring predator traps and bait stations
New Zealand leads world in island conservation: how invasive mammal eradications lead to animals being actively saved
Antipodes Island mouse eradication successfully completed
'Team Rat' Completes World's Largest Island Eradication on South Georgia Island
Lord Howe Island proposed Rodent Eradication
Resolution Island Stoat Eradication
James Russell talks about Seabirds, Rodents and Islands
Researchers placed rat urine in self resetting Goodnature rat traps (left), and used infrared trail cameras (right) to video rats as they responded to the urine. Photo: RNZ / Alison Ballance
