A nor’wester groans in the skeletal fingers of a devastated kamahi forest. It’s spring; these trees should be seizing the sun, turning it into exuberant explosions of flowers. But the canopy, that reticulated energy network of millions of leaves, is gone. Normally it would support a chiming carillon of tui, bellbirds and kaka singing for their lovers. But breeding burns a lot of fuel, and here, many birds won’t find enough sustenance to reach breeding condition—their metabolic switch won’t flip.
That’s because these kamahi trees are also the favoured fodder of another creature, the brushtail possum. Every night, millions of them devour an estimated 21,000 tonnes of New Zealand forest; the leaves, berries, fruit and flowers that would, in pre-pestilent times, have powered the procreation of our native wildlife.
Some birds, experienced breeders, may yet produce eggs and chicks, but it turns out that possums have a taste for those as well; surveillance cameras have caught them robbing nests. And if the possums don’t get them, there’s an excellent chance that rats or stoats or ferrets or weasels or cats or hedgehogs will.
Conservation in New Zealand is mostly about trying to protect native wildlife from the teeth and claws of this plague of our own making—a malignant invasion that has resulted in the extinction of more than 40 per cent of our bird species as well as three frogs, a bat, a freshwater fish, at least three lizards and an unknown number of insects.
Which is why, this spring day, you hear only an echo of the disappeared.
Clyde Graf, a Hamilton hunter, has noticed it too, but he attributes much of this silence to a cluster of molecules—two carbon, two hydrogen, one fluorine, two oxygen and one sodium. Bind them and you have sodium monofluoroacetate, or 1080.
Clyde and his brother Steve grew up in the misty backblocks of the Urewera Ranges, in a tent with no floor. Their father fed them with what he could hunt—deer and pigs. The boys, in turn, became deer hunters. But, says Graf, 1080 “stuffed” the venison business, and the pair turned instead to making hunting and fishing videos.
In March, they released a DVD, Poisoning Paradise – Ecocide in New Zealand, an anti-1080 polemic which claims that the toxin kills native birds in vast numbers, poisons soils, persists in water and interferes with human hormones. According to Graf, Poisoning Paradise will shock viewers with “disturbing, shameful facts that will withstand scrutiny”.
In many ways, the Grafs’ DVD epitomises an enduring hostility towards 1080 by certain sectors of society. Our understanding of the poison has advanced considerably, the use of it has improved, and countless studies point to its obvious merit, as the salvation of much of our wildlife. Yet 1080 remains maligned, even loathed. Could it really be that bad?
In fact, most of the claims made in Poisoning Paradise aren’t new. The poison has been used and studied in New Zealand since the 1950s. There are hundreds of peer-reviewed papers examining the behaviour, properties and persistence of 1080 and its toxicity in creatures from frogs to ferrets to farmhands. Many of these studies provide scientific evidence that contradict the claims made in the DVD and which continue to be perpetuated in the media and public opinion.
Take, for instance, the claim that 1080 contaminates our waterways. Between 1990 and 2008, Landcare Research tested 2098 water samples following 1080 operations. Only three per cent were found to contain traces of 1080 and, apart from one test suspected of contamination, the levels were around 0.2 parts per billion (ppb), well below the Ministry of Health drinking-water standard of 3.5 ppb. Similarly, tests on the toxin’s impact on freshwater invertebrates and fish found no measurable effect—even when exposed to 1080 baits at 10 times the normal density.
It is true that 1080 has killed native birds; smaller, lighter ones such as robins and tomtits are particularly susceptible. This lesson was learned in 1996 when poorly screened carrot baits killed hundreds of both species in the Pureora Forest Park in the central North Island. But DOC responded accordingly, introducing cereal baits, switching to much thinner sowing rates and using green dyes and masking agents in the bait to put the birds off eating it. All this significantly reduced bird deaths; no monitored tomtits died after a 1998 Pureora operation, and robin-nesting success subsequently jumped from 11 per cent to 72 per cent.
DOC also conducted a study, between 1998 and 2002, tracking the fate of kereru and kaka through aerial 1080 carrot operations in Whirinaki Forest in the Bay of Plenty. Radio transmitters were
fitted to birds both inside and outside the drop zone and monitored for a fortnight after the operation. None of the 17 tagged kaka or 15 kereru died.
And in 2007, at the behest of DOC and the Animal Health Board—the two biggest users of 1080—the Environmental Risk Management Authority (ERMA) reassessed the poison. The hearings were vaunted as the ultimate scrutiny, the most complete evaluation of the state of our knowledge. ERMA staff reviewed reams of scientific literature before the panel heard 1400 submissions at public hearings around the country. In the end, it approved the continued use of 1080, conditional upon tighter controls and more research into alternatives.
Yet this has done nothing to appease opponents. Clyde Graf dismissed the review as “a sham; a total waste of time” and anti-1080 groups simply redoubled their efforts. That same year, pregnant women fled an aerial 1080 operation at Karamea on the West Coast on the advice of midwives, marking a new nadir in public perception. “Nobody can guarantee this substance does not cross the placental barrier,” Nelson District Health Board midwife Carol Craven told Danielle Yealands, an expectant mum. Paul Murray of KAKA 1080, a group sworn to banning the substance on the West Coast, justified the advice: “Sodium monofluoroacetate (1080) is a known endocrine disruptor and…developing fetuses are thought to be particularly susceptible to the toxin. The midwives were erring on the side of caution.”
Actually, 1080 is not a known endocrine disruptor. Toxicologists such as Charlie Eason, professor of wildlife management at Lincoln University and research director at pest-control company Connovation, define such agents as “chemicals that act on hormones like oestrogen or androgen activity”, but neither 1080 nor its metabolite, fluoro-citrate, has been found to do so. Does it cross the placental barrier? It’s true that the fetuses of lab rats exposed to high doses of 1080 have suffered developmental defects, but the subjects were fed the toxin daily during the most active period of gestation before any observable effect occurred. However, it remains unclear how a pregnant woman (or anybody, for that matter) could end up ingesting such high doses of 1080 at all.
But the bad press continues. Writing on the KAKA 1080 website in a piece entitled “The Truth and Nothing but The Truth”, hunter and outdoor lobbyist Hans Willems insists that 1080 “is so toxic that skin contact, inhalation, contact with the eyeball or ingesting as little as 0.06 of a metric gram, said to be the size of a full stop, means certain death”. Such claims might accurately refer to raw 1080, the form in which it leaves the lab (although even then, Willems’ figures are dubious). However, in New Zealand, only a few factory staff are exposed to the toxin in that concentration. It is then mixed into either carrot or cereal baits, of which actual 1080 makes up either 0.08 per cent of small baits or 0.15 per cent of large.
Also, aerial operations typically sow 5 kg of bait per hectare, which means that one hectare is left with between 4 and 7.5 grams of toxin spread over it—or, put another way, around 1000 baits, containing a teaspoonful of 1080 between them. Eason cites a highly conservative LD50 (a standard toxicology term referring to the lethal dose needed to kill half of a tested sample) of 1080, which is one milligram per kilogram of body weight. That is, a person who weighs 70 kg would need to ingest 70 mg (or seven bait pellets) for it to be fatal. “Who’s going to be doing that?” he asks. “It doesn’t actually happen.”
If Eason sounds frustrated, it’s unsurprising. There has never been a human death related to ingesting 1080, and he has been restating the facts for decades. Yet hyperbole like Willems’ has found currency as an urban—make that largely rural—myth.
John Cumberpatch is the head of DOC’s 1080 operations. His job is to wrest threatened species from the jaws of stoats, rats and extinction. He has witnessed the tremendous benefits of 1080 on our maligned native species. “The science isn’t perfect—it never is—but we conduct a residual trap catch after every operation, and we know that the knockdown of pests is huge,” he says. “And it lasts longer than we once thought. We used to think that it was only two or three years; now it looks more like four or five years.”
There are several reasons 1080 remains the aerial bait of choice. A single aerial drop of 1080 can kill around 98 per cent of possums and will have a similar success rate on rats. Then it kills any other pests that feed on the carcasses (1080 can persist in dead tissue for months), after which it is metabolised by bacteria and disappears.
The respite it provides gives native birds a vital few seasons to procreate in peace. Experiments have shown what that means for the survival of species such as kaka, which have been monitored at three unprotected sites, and compared with three others under intensive pest control. At Lake Rotoroa, in Nelson Lakes National Park, unprotected kaka made 10 attempts to nest; only one succeeded. Over the next ridge, in the comparative sanctuary of the Lake Rotoiti “mainland island”, 12 out of 14 attempts produced fledged chicks.
It’s the same story on the Tonga-riro rivers, where stoats were sending whio—our blue duck—straight down the creek. In 2004, 10 pairs lost every last duckling. This season, 11 chicks survived to independence, aided by ongoing trapping.
Kiwi have also ridden the wave. Prior to the 1080 drop, just 12 per cent of kiwi chicks survived to independence. The next season, 56 per cent survived. And because 1080 also kills rats, the fantails got a break; chick survival leapt from 10 to 48 per cent.
But, for all the research, all the obvious benefits to biodiversity, and the role of 1080 in reducing bovine tuberculosis infections in farm animals to 0.34 per cent, there is more misinformation circulating about 1080 than ever.
You will still read bumper stickers insisting that “1080 kills everything”.
Psychologists call this “communal reinforcement”—the process by which a belief becomes fact in an ideologically aligned community. The phenomenon, as described by science writer and psychiatrist Ben Goldacre in Bad Science, “is independent of whether the claim has been properly researched, or is supported by empirical data…Communal reinforcement goes a long way to explaining how…testimonials can supplant and become more powerful than scientific evidence.”
Eason says that while much of the fearmongering is “emotive and a little foolish”, he concedes that some concerns are “very understandable”.
That’s because for all the official assurances of strict controls, things have gone seriously wrong at times. A disastrous regional council 1080 operation in Upper Hutt in 2001 poisoned a number of family dogs which had scavenged dying possums that had crawled onto properties. Seven kea died after eating 1080 baits at Franz Josef only last year, and a West Coast farmer blamed the deaths of 10 farm deer on misplaced 1080 baits.
Wellington medical officer of health Stephen Palmer, who gives consents to regional 1080 drops, says he’s had to push pest-control authorities “very hard to improve the way they operated. Some of them were real cowboys.” Since then, he says, “there’s been a huge revolution in the way 1080 has been handled”.
He’s the first to concede that the 1080 debate has strayed from fact. “It’s about people’s perception of risk more than the actual risk. If you don’t address people’s perceived fears, then they remain.”
Phil Cowan, a science leader at Landcare Research, agrees: “We need to find better ways to try to talk about these issues. We’ve gone beyond the science debate, even though 1080 is probably the most researched vertebrate toxin anywhere in the world. Things are often so confrontational that there’s no real progressive discussion.”
So are 1080’s days numbered in New Zealand? ERMA’s endorsement, stresses the authority’s general manager of hazardous substances, Andrea Eng, is provisional. “It’s not a green light; it’s an amber light—proceed with caution. It’s not an approval for all time.”
But, in the absence of a proven alternative, it’s unlikely 1080 will be banned. Fast-breeding pests would reclaim the forest in a few seasons. While anti-1080 groups insist that bait stations, bounties and trapping can achieve anything a helicopter drop can, hard experience and accounting prove otherwise.
Bait stations work well, but they require regular tending and do nothing to stop dogs taking poisoned carcasses. In fact, possums can take in much bigger doses of poison from a bait station, making their remains even more lethal. It is true that in easy country, bait stations can be as economic as aerial 1080, but there are places in the hinterland so dauntingly steep, remote or downright ornery that they’re beyond even the hardiest trapper (the majority of whom prefer to work easier, more profitable countryside anyway). Says Cumberpatch: “It’s simply not possible to spread poison on foot in remote locations. It cannot be done.” Bounties have also been tried before, but ended up achieving little more than the illegal release of more possums.
In many ways, 1080 is the ideal weapon, taking out a host of pests in one hit—but this includes deer, a collateral casualty the hunting lobby will not brook. The Deerstalkers Association helped fund the Graf brothers’ anti-1080 DVD, although Clyde Graf unrepentantly bats away charges of self-interest. “I love seeing deer out in the wild. This country is better off for having them. Don’t give me evolution stories and all this nonsense… deer are here, and we’re not getting rid of them.”
Such comments convince Charlie Eason of the need for more pest-control options. “There’s a gap between conventional poisons and the demands and expectations of modern biocontrol that need to be filled,” he says.
“Even if you’re an advocate of 1080, you could see that having a range of tools at least takes the pressure off 1080 use.”
It might be the best we have, but public concern and hunting-lobby pressure are driving a quest for non-toxic controls, or at least more species-specific toxins. The development and adoption of such controls will, agencies hope, ease hostility towards their pest-control programmes, but they will bring problems of their own.
We already know that when stoat numbers are knocked down, rat numbers can soar in their absence, a catastrophe for native birds. That means any operation aimed at stoats will have to simultaneously tackle rats, to avoid a plague. Our grasp of pest dynamics will have to be meticulous, our timing impeccable.
Whatever innovations may come (see boxes in this feature), pest control is a job for life, or at least for the foreseeable future. “People think you can control pests and that’s the end of the problem,” says DOC scientist Elaine Murphy. “They don’t understand that you can hit them for one season, but you’re back to square one the next. That’s not a failure of pest control; it’s just something you have to keep doing, like track maintenance.
“I’d hate for us to walk away now. We can’t protect all the species we have, but I’d like for us to try and protect as many as we can, because I think in 20 or 30 years’ time, people will look back, and ask, ‘Why on Earth didn’t they do that little bit to keep that species?’”