Science against 1080

Will NZ’s Department of Conservation win against rodents and stoats with 1080 poison?
Scientist Dr Jo Pollard puts the counter view.

Published in the Greymouth Star, Tuesday, May 7, 2019

Dr Jo Pollard

Dr Jo Pollard – BSc (Hons), PhD, Zoology

The New Zealand government’s Department of Conservation (DoC) is responsible for managing our land and natural resources for the purposes for conservation. The department and its precursors have conducted a campaign that spreads food (cereal or carrot) baits laced with 1080 poison (sodium monofluoroacetate) widely throughout New Zealand’s forests in a sixty year long attempt to reduce numbers of the possum, a marsupial introduced from Australia to form the basis of a fur trade.

During the last 2 decades DoC has increasingly used aerial 1080 poisoning in an attempt to combat rodents as well as possums. Under operations called “Battle for the birds” 600,000 ha was poisoned in 2014, 840,000 ha in 2016 and 600,000 ha in 2017. DoC has now received an extra 81.2 million dollars for pest control and is set to aerially poison the largest area ever targeted: approximately 1 million ha of forest in 2019/2020.

DoC’s current rationale is that it needs to kill rodents and stoats, otherwise these creatures will eat large numbers of native animals after multiplying rapidly in response to masting (seeding) vegetation. Given the enormous cost and wide scale nature of DoC’s aerial poisoning, critical examination of this practice is warranted.

The first rodent species to join New Zealand’s ecological community, the kiore, arrived with Polynesian people in about 1300 AD. Europeans brought the Norway rat about four centuries later, followed by the ship rat in the 1800s. Another rodent, the mouse, also arrived with Europeans in the 1800s. Stoats were introduced from Britain in the 1870s to control rabbits.

Rodents breed rapidly under favourable conditions. Plagues of kiore were familiar to the Polynesian settlers (Maori) and continued into the 1800s, until on NZ’s main islands this rat species was replaced by the European rodents. Plagues of rodents (usually mice, rather than rats, in beech forests) often follow periodic masting events. Rapid population growth can fuel short-term increases in numbers of their major predator, the stoat, which also breeds rapidly under favourable conditions.

DoC and its precursors have pursued a policy of nationwide poisoning for decades with scant evidence of success as measured by increased bird numbers and species removed from the endangered list. Those rare successes that have occurred have invariably involved many other interventions in support of the target species. The research strongly suggests that there are several major flaws in DoC’s claim that aerial poisoning with 1080 will save native animals from rodents and stoats.

1080 does not usually kill mice, in fact mouse numbers are usually observed to rise very soon after aerial poisoning. It is thought that because mice can detect the poison in food baits they avoid eating them. They most likely flourish because rats and other competitors and predators have been killed off and there are ample food resources left in the wake of the poisoning. Unfortunately mice are far from benign, being harmful to native vegetation and populations of both invertebrates and vertebrates.

Rat numbers are supressed after aerial 1080 poisoning – but not for long. Vastly increased numbers usually arise within months, often to levels well above those seen pre-poisoning.These increases can have devastating ecological effects. For example Landcare scientists reported in 2007 “In the poisoned block, the number of large invertebrates known to be eaten by rats soared after rat numbers were reduced to near zero, and then plummeted as rat numbers exploded to very high levels.”

As Landcare scientists Andrea Byrom and others pointed out in 2013, increases in rodents following 1080 poisoning operations create excellent conditions for the proliferation of stoats. At Okarito, on the West Coast of the South Island, a 1080 operation in 2011 was followed by large increases in numbers of mice, then rats, then a stoat plague in late 2012. DoC’s recently published study on kiwi productivity over 22 years at Tongariro shows exactly this same pattern for rats and mice, with rat numbers rising rapidly to very high, stable levels within 18 months of poisoning and stoats increasing steadily. DoC is now using this pattern to justify ever-shorter intervals between poisonings.

Stoats are not reliably killed in 1080 operations because they are carnivores; they don’t eat the cereal or carrot baits and are only killed if they eat poisoned prey. Unfortunately stoats respond to the sudden poisoning off of rat prey by turning to eating native birds. In 2002 DoC reported “Four months after an effective possum and rat knock-down by a 20,000-ha aerial 1080 operation over Tongariro Forest, stoats reappeared in the centre of the forest and began killing kiwi chicks. So far five of the 11 chicks have been predated, and all in the centre of the treatment area.”  King & Murphy (2005) reported that “After successful poison operations against rats, there were strong and consistent responses by stoats to eat more birds”.

1080 is non-selective. It acts by blocking respiration within cell mitochondria. It is harmful to a very broad range of organisms including bacteria, fungi, plants, nematodes, insects, birds, mammals and snails. Widespread mortality was recorded in the first studies on effects of 1080 on birds; it was reported in 1978 that “it is clear that a wide variety of small birds commonly found in New Zealand’s forests and bush are susceptible to 1080 poisoning.” The following bird species have been found dead in areas poisoned with 1080: Australian harrier, weka, pukeko, kaka, kea, morepork, rifleman, NZ pipit, brown creeper, whitehead, grey warbler, fantail, tit, robin, silvereye, kokako, tui, kereru, kakariki and fernbird. But rather than quantifying these losses by measuring numbers of actual birds left alive after poisoning, DoC has reported on the “nesting success” of individuals (which is expected to rise if a population is largely killed off, due to less competition) and bird calls (which are also expected to rise after poisoning if birds are calling for dead mates or searching for new ones).

The endemic species present before the NZ government started its aerial poison onslaughts in the name of conservation had weathered decades of stoats, centuries of rodent plagues and had evolved with masting vegetation and natural avian predators. Predation is a natural ecological phenomenon. In birds, nest predation is a key source of selection pressure and in the presence of predators, individual birds learn to make informed choices regarding nesting sites.

In contrast, poisoning is a wholly unnatural event that wipes out the precious genetic material of rare species. Wholesale poisoning favours the fast breeding, invasive, generalist pest species such as the rat, which eats almost anything. The use of 1080 poison is especially contra-indicated because of its incredibly broad spectrum toxicity and inability to control mice, plus indications that rats will become less and less vulnerable to it: genetic selection for resistance to 1080 has been observed in laboratory rats and individual rats seem to develop tolerance to 1080 after a small dose, unlike other animals.

NZ’s slow breeding, rare, specialised endemic species don’t stand a chance as DoC’s poisoning intensifies. Winning against rats with aerial 1080 poison will be at the expense of everything endemic. American rat biologist Loretta Mayer stated:  “Frankly, rodents are the most successful species…after the next holocaust, rats and Twinkies will be the only things left.”

[Dr Jo Pollard is an independent scientist with particular interests in animal welfare, NZ’s ecology and scientific integrity. For references to the research cited above and reviews by Dr Pollard and other concerned scientists visit]

Lies, damn lies and statistics

Response from Dave Hansford published in the Greymouth Star, 17 May 2019

Anti-1080 activist Dr Jo Pollard was careful not to give readers too many facts in her anti-1080 polemic (Science against 1080’, Greymouth Star, May 7) – just those that seem to support her agenda.

Oddly for an ‘independent scientist’, she broke a number of cardinal scientific rules.

Scientists begin every paper by setting out their affiliations to science or academic agencies. “Independent’, in Dr Pollard’s case, is a euphemism for the reality that she holds no post at any science agency or academic institution.

Secondly, scientists always declare any potential conflict of interest that might imply a bias or agenda. Jo Pollard neglected to tell readers that she owns The Wild Treats Company, pet food business based on wild meat that offers, among other things ‘possum crumble’ and possum twists’ for dogs.

Thirdly, good scientists declare not only findings that validate their hypotheses, but those that contradict or weaken them. It is precisely this honesty that Dr Pollard exploits when she plucks quotes from scientific papers that, when presented with context, appear to make 1080 look bad. This is called cherry-picking, and it is a practised deception.

While she is happy to cite a single 17-year-old report about the killing of kiwi chicks by stoats in Tongariro, Dr Pollard neglects to tell readers that it was part of a much bigger 22-year longitudinal study which found incontrovertibly that kiwi chick survival is boosted by 1080 operations, and demonstrably declines two years after them as pests rebound. Unlike Dr Pollard, I’m happy to supply a reference, so you can go and check for yourself: Robertson et al: Landscape-scale applications of 1080 pesticide benefit North Island brown kiwi (Apteryx mantelli) and New Zealand fantail (Rhipidura fuliginosa) in Tongariro Forest, New Zealand. Notornis, 2019, Vol. 66:1-15.

Similarly, Dr Pollard quotes a 1978 Forest Service report which found that ‘small birds’ could indeed be killed by 1080. What she didn’t tell you was that 41 years ago, the Forest Service used 1080 at doses and sowing rates more than 10 times heavier than those used today, and that they used carrots baits laced with jam – irresistible to many birds. Bird bykill plummeted when these practices were stopped decades ago, but Dr Pollard wants you to think they still continue today.

Other stuff she simply got wrong: not only is there no evidence of a ‘stoat plague’ in 2012 at Okarito, a 2018 study shows clearly that stoat numbers fell drastically there after a 1080 drop the previous year, and ‘… remained near zero at Okarito for the kea nesting seasons in 2011 and 2012’. You can read it for yourself: Kemp et al: Effects of 1080 on kea productivity. New Zealand Journal of Ecology (2018) 42(2): 158-168.

Or you can just take a walk up the Landsborough, and listen. A 21-year study there recently confirmed that mohua, once rare, are now the most common native bird there, up 300-fold after six 1080 operations since 1994.

Cherry-picking other people’s work to create an illusion is not ‘science’. Real science will tell you everything it knows. Activism only tells you want it wants you to think.

Dave Hansford is the author of Protecting Paradise: 1080 and the Fight to Save New Zealand’s Endangered Wildlife. He has provided this opinion in conjunction with Forest and Bird.

1080 Science

Reply to Hansford by Dr Jo Pollard. Published in the Greymouth Star

The fact that the Department of Conservation (DoC) hauled out a journalist, Dave Hansford, to defend their current round of aerial poisoning blitzes (Greymouth Star, 17 May), rather than a scientist, gives us a glimpse of the only element of truth to be gleaned from their response – their actions cannot be defended using science. Hansford is well out of his depth. He has unwittingly picked on two recent publications in support of his argument, both of which provide shining examples of DoC’s fraudulent misrepresentation of their own results.

One concerns kea at Okarito (NZ Journal of Ecology, 42). Hansford claims there is no evidence of the stoat plague that followed the poisoning there in 2011. As a journalist he should probably be expected to read the text of the study, rather than to rely on looking at the pretty pictures.  DoC chose to cut off the graph where the results became inconvenient!

DoC’s original in-house report on this study, obtained via Official Information request, shows stoat tracking rates rocketing upwards to 90% in December 2012 (Kemp et al., 2015, unpublished*). The published version stops the graph short of this in October 2012, when stoat tracking was 5%!

The second paper relates to a 22 year long monitoring effort at a Tongariro kiwi sanctuary. Hansford and DoC claim that this study shows how beneficial 1080 is to kiwi. Unfortunately, but unsurprisingly, there are two huge flaws in the reported results.

The study purports to show that survival rates for kiwi increased dramatically in the first two years after a round of 1080 poisoning. What actually happened was that naturally raised birds were supplemented with artificially reared ones and their survival data (unaccountably) was combined. The study fails to give data on the addition of these birds. Also, the study merely compares survival within 5-year cycles of aerial blasting with 1080 poison. It demonstrates the point of my original article clearly: that following 1080, pest numbers can rise dramatically within months as a direct result of the poisoning  and that DoC is using this pattern of rodent boom and bust to justify more and more frequent poisoning (the study concludes that poisoning every 3 years would be better than every 5 years).

DoC propaganda and Hansford’s efforts continue to cite Mohua management in the Landsborough Valley as an example of just how successful aerial 1080 has been. But O’Donnell & Hoare (2012; NZ Journal of Ecology, 36) provided the actual details of DoC’s management there: continuous ground trapping for stoats plus initial trapping and ground-based poisoning of possums and four aerial 1080 operations over 11 years. The authors stated that “we are unable to apportion increased abundance of mohua to a particular component of the pest control programme”.

Hansford insinuates I lack scientific credentials – as author of 31 refereed scientific publications and 30 technical publications from my 14 years as a government scientist I have an excellent rating internationally. He may like to compare that record to the record of DoC staff. As Hansford has discovered, I have recently started a company that uses animals deemed to be “pests” on farmland (rabbits, possums, goats and wallabies) as a resource for pet food. This is because after 12 years of researching and complaining about wasteful, harmful, inhumane poisoning for pest control I have set about demonstrating there IS a sensible alternative.

*Kemp, J., Cunninghame, F., Barrett, B., Makan, T., Fraser, J., Mosen, C., 2015, unpublished. Effect of an aerial 1080 operation on the productivity of the kea (Nestor notabilis) in a West Coast rimu forest. Department of Conservation report. 15 pp.

1080 Cherry Picking

Reply to Dave Hansford by Ron Eddy, Nelson. Published in the Greymouth Star

I find Dave Hansford’s attempt ‘Lies damn lies and statistics’ (Greymouth Star, May 17), to belittle and discredit scientist Dr Jo Pollard’s opinion piece in the Greymouth Star on May 7, to be rather humorous.

Mr Hansford accuses Dr Pollard of ‘cherry picking’, describing it as ‘practised deception’, but then descents straight into the use of cherry picking himself.

In question Dr Pollard’s claim of a ‘stoat explosion’ at Okarito in 2012 he claims a 2018 study showed stoat numbers fell drastically after a 1080 drop the previous year and stayed low at Okarito for the kea nesting season of 2011 and 2012. What Mr Hansford failed to say was that eight kea died of 1080 poisoning during that 2011 aerial 1080 operation. Was the loss of those eight poisoned kea factored into DOC’s 2011-12 breeding season results? Not likely.

A November 27, 2017 Facebook (1080 Eyewitness Open) comment by Dave Hansford reads in part: ‘There have been just two known keas deaths to 1080 in the last five years’. That statement is so wrong. DOC’s own kea research tells us that in the ‘five-year’ period Mr Hansford quoted, 2012 to 2017, aerial 1080 operations killed nine kea.

If he has taken his time period from DOC’s original 2008 research start the total killed would be 24 kea. Why did Handsford ignore those extra 15 kea? He was ‘cherry picking’!

Mr Hansford claims he reads science papers … why didn’t he read DOC’s very pertinent kea 1080 death chart? I prefer to read the works of independent scientists such as Dr Jo Pollard in comparison to the opinions of someone who has no known qualifications and works in conjunction with Forest and Bird.

Another fact: in the mid-1970s Forest and Bird called for a government review of 1080 toxin use because they had deep concerns over the large loss of native birds as a consequence of 1080 toxin operations. Now they support 1080 toxin use. What caused this dramatic policy U turn?