Get the facts

Responding to common misconceptions about predator control to protect pukunui/New Zealand Southern dotterel on Rakiura

With operations underway to protect pukunui/southern dotterel from extinction and trial tools and methods for eradicating introduced predators on Rakiura there’s a lot of action and discussion happening.  

Unfortunately, we’re seeing some inaccurate information being circulated online. 

Below, we’ve summarised some key facts and the scientific studies to back them up in response to the most common misconceptions we’re hearing.  

We recognise there’s a lot of information to digest, so we encourage people to get in touch if you have any questions or concerns: info@zip.org.nz

Fact: Rakiura supports a rich array of native species—but the ecosystem has been significantly affected by the introduction of mammal predators.

Misconception: Rakiura is often described as “pristine and untouched”.

Stewart Island/Rakiura supports a remarkable range of native species and habitats — but these ecosystems have been deeply altered since human arrival. Like the rest of Aotearoa, the island evolved without land mammals for over 80 million years, apart from three bat species (one now extinct), resulting in wildlife uniquely vulnerable to introduced predators

While Rakiura retains more native biodiversity than many parts of New Zealand, this appearance can be misleading. Since the arrival of humans and invasive mammals — such as rats, possums, and feral cats — the island has suffered the same steep declines seen elsewhere. Birds like the mohua/yellowhead, bush wren, tīeke/saddleback, snipe, kōkākō and kākāpō once thrived here but have now vanished. Fossil evidence shows that millions of Whenua Hou diving petrels once bred at Mason Bay, only to be wiped out by rats in a single generation. These losses also extend to native lizards, invertebrates, and entire forest systems.

The idea of Rakiura as “untouched” reflects a shifting baseline — we celebrate what remains, forgetting what has already been lost.

Rakiura is ecologically important and still harbours species found in few other places — but it is not untouched. Recognising the island’s altered state is the first step toward protecting and restoring its unique ecosystems before more species vanish.

Fact: 1080 helps native wildlife recover.

Misconception: “1080 causes silent forests”

Aerial 1080 operations are among the most effective tools for controlling introduced predators such as rats, stoats, and possums. Long-term studies show that reducing predator pressure leads to clear rebounds in native bird populations and the recovery of forest ecosystems. Far from falling silent, forests typically grow louder and more vibrant after 1080 drops. Extensive monitoring also shows no harmful effects on invertebrates.

Some key findings:

  • Mohua populations have increased dramatically following aerial 1080 drops (O'Donnell et al. 2017, Elliott & Kemp 2016).

  • Kākā breed more successfully and produce more fledglings after predator control (Greene et al. 2004).

  • Kiwi chick survival increases significantly when stoats are suppressed by 1080 (Robertson et al. 2011)

  • A 10-year OSPRI study found that 12 of 14 native bird species increased or remained stable following 1080 use (OSPRI 2017).

Independent reviews, including from the Parliamentary Commissioner for the Environment, support these findings and confirm that 1080 is a critical conservation tool.

Fact: 1080 is a uniquely suitable tool for New Zealand’s environment.

Misconception: “Other countries have banned 1080”

1080 is uniquely well-suited to New Zealand’s environment. Unlike most countries, Aotearoa has no native land mammals apart from a few bat species.

In most countries, 1080 is not banned — it simply isn’t registered because those countries have native mammals that would be at risk. In New Zealand, its use is based on a unique ecological need. In this context, 1080 remains one of the most effective tools available to protect native species from extinction.

Fact: Native species and ecosystems on Rakiura are well studied and understood.

Misconception: “There is no baseline data on native biodiversity”

Fact: Native birds, reptiles, and invertebrates are much less susceptible to 1080 than introduced mammals.

Misconception: “1080 kills everything that eats it”

The toxicity of 1080 varies widely between species, which what makes it an effective tool for targeting introduced mammal predators in New Zealand.

Species and their known lethal dose of 1080 (LD50 in mg/kg of body weight)

Rats = 0.34–2.7

Possums = 0.8-1.2

Dogs = 0.06–0.1

Cats = 0.3

Deer = 0.5

Birds (e.g. kiwi, robins) = >8

Reptiles = 43.6-543.2

Aquatic invertebrates = 350

Human = 2.5

(Sources: Eason et al. 2011, EPA 2007)

Native birds, reptiles, and invertebrates generally have much higher tolerance levels than introduced mammals. Dogs are extremely susceptible, and most other carnivores are highly sensitive to poisoning. Herbivorous mammals are less sensitive, and birds and reptiles less susceptible still (Atzert 1971; Rammell & Fleming 1978; Eisler 1995).

While individual non-target deaths can occur, large-scale monitoring consistently shows either little to no impact at population-level for birds, reptiles and invertebrates or population-level benefits.

Contrary to this, 1080 increases the breeding success and survival rate of many native species.  

Fact: 1080 breaks down rapidly in water.

Misconception: “1080 contaminates drinking water”

1080 breaks down rapidly in water, including in natural bodies of water such as streams. It is usually undetectable within 24 hours.

1080, or sodium fluoroacetate, is soluble in water: it is quickly diluted to non-toxic levels. It also breaks into its constituent compounds by the action of bacteria or other fungal networks. Once broken down, it is no longer toxic.

A 1080 pellet is not like a Disprin. While it is soluble, 1080 is no longer effective as a toxin once it has been in contact with water.  Streams, rivers and oceans are extremely large bodies of water and have a powerful dilution effect.[DF2] 

The Ministry of Health’s safe drinking threshold is extremely conservative: 0.003 mg/L. For a 70 kg adult to reach a toxic dose, they would need to drink over 230,000 litres of water at the maximum allowable level — far more than any practical exposure scenario.

More than 2000 samples of water used for human drinking supplies were tested between 1990 and 2023. Of these, only four contained traces of 1080 at concentrations of 0.1 to 0.2 ppb. These are extremely low levels that are well below the Ministry of Health requirement. They posed no risk to human health.

Fact: Aquatic species do not accumulate 1080 at levels dangerous to humans or themselves.

Misconception: “1080 contaminates kaimoana”

Aquatic species do not accumulate 1080 at levels dangerous to humans or themselves. NIWA studies on koura (Lyver et al. 2005) show rapid elimination of 1080 even under artificial exposure to amounts of bait much higher than is realistic for an aerial operation. Similar studies on trout (Booth et al. 1999) and eels (Lyver et al. 2005) show negligible residue accumulation.

For example, based on the levels found in Lyver’s 2005 study, to reach a lethal dose a human would need to consume 40 kg of koura tail meat in one sitting.

Fact: Predator control supports sustainable mahinga kai on the Tītī Islands.

Misconception: “It will harm tītī harvest”

Many Tītī Islands are predator-free today precisely because aerial toxins were used in past eradications. These islands now reap the benefits: healthy harvests, booming seabird populations, and restored mahinga kai.

Without widescale predator control, this harvest could disappear entirely.

Fact: We are working in collaboration with the wild catch and marine farming industries to protect their interests throughout predator control operations.

Misconception: “It will harm the fishing and aquaculture industries”

Over 60 aerial 1080 operations were completed across Aotearoa in 2024 alone. These operations interacted with and were adjacent to many primary industry activities, including dairy, meat, wine and wild catch fisheries. Wherever aerial 1080 is used, operational leads work alongside these industries to make sure that their interests are protected.

The key risk, as identified by these industries, is not food safety — but market perception. Despite their regularity across New Zealand, predator control operations using 1080 have not had a negative impact on wild catch fishing and marine farming industries.

We continue working closely with wild catch and marine farming industries on Rakiura to ensure their interests are safeguarded. The wild catch industry has publicly supported the engagement process so far and the goals of the project.

Fact: There have been no recorded cases of aerial 1080 operations causing harm to human health.

Misconception: “Residents risk being exposed through food harvesting”

Based on data collected in Ogilvie et al (2009), plants are able to take up low levels of 1080 from cereal baits in the environment. However, at the highest measured 1080 concentration found in puha during this study, a 70 kg person would have to eat 9.3 tonnes of affected plant material in one sitting to receive a lethal dose.

1080 does not accumulate in the environment, and studies show that small doses are quickly excreted by the body. Long-term, low-level exposure is not harmful – a cup of black tea contains 1080's active ingredient (fluoroacetate) at about 1.5 times the Ministry of Health's legal limit for 1080 in drinking water

There is a caution period in place for the harvest of animals for consumption following aerial 1080. This caution period and the associated buffers are based on the known home ranges of each animal.

If these cautions are abided by, there is no risk to human health from harvesting food from the land.

DOC’s Pesticides Summary shows the areas where these caution periods are active.

Fact: The vision of a predator-free Rakiura has been explored, debated, and refined over many decades.

Misconception: “Work towards the Predator Free Rakiura project is being rushed”

The progress of the project today builds on decades of research, assessment and discussion, including: 

Operational progress towards a Predator Free Rakiura is currently limited to a 7,000 hectare trial within Rakiura National Park. This trial is designed to build knowledge and inform future decisions. Any further steps will be shaped by what we learn and ongoing conversations with the community.