The Government's use of 1080 poison has long drawn angry protest from opponents, who push a range of scientific claims about its efficiency and danger. In his new book, Protecting Paradise, science writer Dave Hansford scrutinises each of the claims - and concludes 1080 isn't the evil it's so often painted as. He talked to Herald science reporter Jamie Morton.
What made you want to write this book? Was there any particular event that triggered it?
There was no defining trigger point, but I'd been writing about pest control off and on for 15 years, and it became ever-more frustrating that the same old myths and misinformation about 1080 just kept on orbiting the national conversation.
They're all so easily debunked, but it's like whack-a-mole - no sooner is one countered with the facts, than they trot out another one.
I got a strong sense that there were lots of people out there who were rightly concerned about 1080, but with so much propaganda about, they weren't sure who or what to believe.
So I decided to hold each myth up to the scientific evidence in turn, to offer a kind of reference point they might feel like they could trust.
As a science writer, what have been your own interactions with the topic?
In 2004, I think it was, I travelled round the North Island for the Department of Conservation, gathering up the experiences of community groups engaged in pest control.
They told me about their successes and failures - it's important to remember that back then, there were none of these fantastic self-resetting traps, so trapping was very laborious, and painfully inefficient - each trap could only go off once, then it sat there redundant until someone came along to reset it.
So it was a hard grind for ordinary volunteers - one rat plague and all their great work was undone.
They talked about the benefits of getting regular 1080 drops, just to zero the pests and give themselves - and the birds - a breeding season in peace.
In 2010, I travelled the country conducting what turned out to be a sort of oral history, listening to older farmers talking about the truly dreadful days, back in the 70s and 80s, when bovine TB was practically epidemic.
Some got emotional just recalling the memory of herds they'd struggled and borrowed for to build up from scratch, only to see them test positive and get carted off for slaughter.
They were terrible times, and many went to the wall.
This was before we truly understood the role of possums and ferrets as vectors of the disease, so the worst part for these guys was not knowing what to do about it.
TB Free published those stories as a DVD and a pdf download: I think you can still get it from their website.
Can you tell us a bit about how you gathered the information for your book, and where the journey took you?
Well, like most science writing, a lot of it was reading - reams and reams of research papers, theses, conference proceedings, powerpoints, datasets - there are 30 pages of references in the back.
Because so many opponents refused to speak with me, I had to get a handle on their views instead by following anti-1080 Facebook pages, so there were long evenings doing that.
In between times, I'd hit the road. I went to the Coromandel to witness a 1080 operation for myself.
I spent a few days afterwards combing the bush looking for all the death and destruction - the slaughter of native birds etc - that activists insist happens after every drop.
I never found evidence of any, despite going off-track with a GPS and conducting long grid searches and bird call counts at different locations.
I travelled the West Coast, where I was fortunate that a couple of committed anti-1080 activists granted me interviews - they filled a conspicuous gap in the book.
I spoke with Maori people about their very special relationship with the forest, and how they struggle to reconcile poison pest control with the principles of tikanga.
I visited the Centre for Wildlife Management and Conservation at Lincoln, where so much innovative pest control work is going on - efforts to find an infallible stoat lure, for instance, and to develop an autonomous, species-specific toxin dispenser.
In Wellington, last year, I attended the anti-1080 movement's march on Parliament.
I went to public meetings to hear NZ First MP Richard Prosser selling his plan to get 1080 banned.
I followed DOC field technicians around the Victoria Range, catching and individually tattooing rats.
There was never a dull moment.
You've focused much of your book on testing the claims that opponents of 1080 often cite. Can you share a few of these?
The one people hear most often is that 1080 kills everything.
One look at the toxicology studies tells you that's untrue: some kinds of animals are more sensitive to 1080 than others.
It's highly toxic to mammals, and unfortunately, dogs are the most acutely susceptible.
Birds are much less so.
Some invertebrates appear to be quite sensitive to 1080, depending on circumstances, while others - like worms - seem not to be bothered at all.
The same with aquatic invertebrates.
Reptiles are very resilient to 1080, as are fish - and the Cawthron trout research proved that - and it's practically impossible to kill amphibians.
Some people also worry about what 1080 does once it lands in water.
The answer to that is that it begins to dilute, very quickly - it's a salt, after all.
So much so that water testing generally has to be done within eight hours - and ideally sooner - if it's to find any meaningful traces at all.
Out of more than 3000 tests from waterways in 25 years, just four have found any trace of 1080 in municipal supplies, and they were all tiny fractions of Ministry of Health permissible levels.
Despite our conservation scientists and figures such as Parliamentary Commissioner for the Environment Dr Jan Wright already having addressed these concerns, why in your view does 1080 remain such a heated issue? Is there something uniquely "New Zealand" about all the controversy?
Well, New Zealand uses around 90 per cent of the 1080 produced, so I guess that certainly makes us unique.
There's a good reason we use so much: every other country has native mammals it can't risk harming with poisons, while, except for three types of bat, all our mammals are introduced pests, so 1080 might have been designed from the ground up for New Zealand use.
There is no myth about 1080 that hasn't been comprehensively debunked many times over.
Yet those myths are still propagated by sectors of the hunting community, and more recently, New Zealand First.
If this were all about getting to the truth of the matter, then those claims would've stopped being made long ago, but they persist.
That tells me there's something else going on here, and it would seem to be a deliberate campaign of misinformation to secure a political agenda.
1080 is known to kill deer, so some hunters consider that it's impinging on their sport.
That's undoubtedly a big reason so many myths are still being circulated.
In New Zealand First's case, it's clearly spotted an opportunity for votes - it means to pick up the hunting constituency that Peter Dunne will eventually leave ripe for the picking.
If it's really a public relations battle that has to be won, how should the likes of the Department of Conservation be more pro-active in countering what the anti-1080 community puts out there?
After a year and a half looking at this, I've concluded that 1080 opposition has nothing to do with science.
In some cases, it's about personal ethics - many people object to the animal welfare implications around poison, and I have no issue with that.
In other instances, it's part of a bigger belief-based system, which research is starting to reveal may very well be rooted in conspiracy thinking.
Finally, as we've seen, there's a political motivation there as well.
No matter what the basis for that kind of dissent, it's very clear that simply adding more information, providing more scientific evidence, won't shift those people, but I didn't write the book for them.
I wrote it for those people who are still undecided, or conflicted about 1080, but who prefer to form their positions on the strength of evidence.
I think the most effective advocacy of all is success: look at Abel Tasman National Park, where Project Janszoon has shown very clearly, that, if you get the pest off their backs, our birds, and snails, and lizards and insects just thrive.
People saw there that the sky didn't fall in when the Park got 1080 in 2014: but what they did see were kaka, and robins, and kakariki returned to the park.
They saw the giant snails rebound in numbers.
They heard the bellbirds.
It's real-world transformations like that which people will appreciate most, I think.
Have you come under attack yourself for writing this book?
Not physically, but there have been all the usual conspiracy theories floated: apparently, I'm a frontman for some evil Government plot to profit from 1080.
I'd make far more money if I just had a dollar for every opponent that's sworn never to read the book, but then goes on to tell me everything that's wrong with it.
Finally, if there's one message you want your book to leave people with, what is it?
In the end, the decision is very simple: we can have our forests full of native wildlife, or we can have them full of rats, stoats, possums and cats.
Birdsong, or silence.
The choice is up to us, but there's no time left for sitting on the fence - we must take each take a position and get behind efforts to save our forests and our wildlife.
A Predator-Free 2050 would be the most wonderful legacy we could leave our grandchildren.
Pest control isn't all about 1080 - it's about trapping, about hunting, about bait stations and before long, we'll need to have a difficult conversation about gene drive as well.
All these tools have their particular strengths, and the smart thing to do is use each to best effect and budget.
Time is tight, and we don't have the luxury of choice.
Protecting Paradise: 1080 and the fight to save New Zealand's wildlife. Potton & Burton, RRP $34.99