DOC and ZIP partnered to deliver this operation, which was an urgent, stand-alone measure to prevent the extinction of pukunui. ZIP is also responsible for developing and implementing the eradication approach for Predator Free Rakiura.

While the primary focus is protecting pukunui, this operation presented an opportunity to gain critical insights into predator behaviour and potential control methods on the island. To make the most of this opportunity, ZIP is conducting a small-scale eradication trial at a site of approximately 6,500 hectares within the wider operational area.

The trial will help determine the effectiveness of aerially applied 1080 to eradicate the three rat species on Rakiura, before the next step towards eradication gets under way. ZIP has already seen success with aerially applied 1080 as an eradication tool for ship rats but needs to understand more about its effectiveness on kiore and Norway rats. The trial will also help show how effective deer repellent is for reducing the impact of 1080 on white-tailed deer, and whether it reduces the effectiveness of the bait on the target rat species.

You can find more information about the trial and the wider Predator Free Rakiura programme at: https://www.predatorfreerakiura.org.nz/.

Consultation on potential effects of aerially applied cereal bait pellets containing 1080 was carried out alongside the operational planning. Community input was sought through a range of channels, including a series of public meetings in Oban, drop-in sessions, and direct engagement with key stakeholder groups and community members in person and via email.

Feedback received during this consultation helped to shape the final design of the operation. Community and stakeholder concerns were considered in detail and several changes were made to address these, including:

• Keeping hunting blocks open, with advice not to consume meat until cautions lift 

• Applying deer repellent bait in bookable hunting blocks

• Shifting deer monitoring to Doughboy Bay

• Adjusting operation boundaries to avoid some bookable hunting blocks 

• Testing the Rakeahua River and Doughboy Creek for 1080 following bait application

• Agreeing that no bait be sown into the ocean

• Establishing a land-based loading site near Mason Bay to avoid loading bait into helicopter buckets for sowing from ocean-based vessels

We continued to engage with the community as the operation progressed and encourage community members to continue contacting us via pukunui@doc.govt.nz with any questions or concerns.

The pukunui / Southern New Zealand dotterel population is monitored annually through flock counts conducted in April. These counts are an important tool for tracking trends in the population and will indicate whether predator control methods have been successful in protecting pukunui during the 2025 breeding season.

The Pukunui Recovery Project is working towards a long-term goal to rebuild the pukunui population to at least 300 birds by 2035. Ground-based trapping will continue during and after the aerial 1080 suppression operation. Pukunui breeding success will guide future decisions about predator control methods, including whether additional aerial operations are required.

In the longer term, achieving the vision of a Predator Free Rakiura would remove the need for future suppression efforts—providing a safe environment where pukunui and other native species can recover and thrive.

Oban has more bird life than other parts of Rakiura, with kākā, kererū and tui regularly observed. This is likely because:

• Regular trapping has occurred in and around the township for many years, for example the extensive trapping work carried out by the Stewart Island Rakiura Community and Environment Trust (SIRCET)

• Oban is in close vicinity to Ulva Island which is predator-free and hosts a range of native species, some of which have large home ranges and travel around the township.

• Oban also has a variety of urban food sources for birds like kākā and kererū that are not available elsewhere on the island, such as exotic fruit trees.

The operation to protect pukunui aims to reduce populations of possums and rats (via direct bait consumption), and feral cats (via secondary poisoning), while trialling tools and techniques for eradication of three rat species on Rakiura.

The operation began in June, and the final step was delivered in August. This timing was carefully selected to provide maximum protection for pukunui ahead of their spring/summer breeding season.

The operation was carried out in two phases. Each phase began with the distribution of non-toxic pre-feed bait to prepare predator species to eat the toxic bait that was applied afterwards.

Phase 1: COMPLETED JUNE/JULY 2025

Two applications of pre-feed non-toxic bait within the ~6,500-hectare eradication trial block, followed by toxic bait at a target rate of 4kg/hectare.

Phase 2: COMPLETED AUGUST 2025

One application of pre-feed non-toxic bait across the full operational area - approximately 43,000 hectares - followed by one application of toxic bait at a target rate of 2kg/hectare.

The exact timing for any operation is weather dependent: 48-72 hours of fine weather is required to deliver each application of bait.

During the Phase 1, within the eradication trial area, bait was sown at a target rate of 4kg/hectare.

During the second phase, in which the full operational area was treated, bait was sown at a target rate of 2kg/hectare.

This means that the ~6,500-hectare eradication trial area received a total target rate of 6kg/hectare between the two phases.

The toxic cereal bait pellets used are dyed green and contain 1.5 grams of 1080 per kilogram of bait. At an application rate of 4kg of cereal bait per hectare, that’s the equivalent of less than two teaspoons of 1080 spread across an area the size of a rugby field.

Multiple helicopters are used to distribute bait within the operational area.  To ensure complete and consistent coverage, pilots use Tabula—a GPS-guided software system that enables them to fly evenly-spaced flight lines with precision. This technology also allows multiple aircraft to coordinate effectively while working within the same area to ensure total coverage of the operational boundary.

During baiting, helicopters typically operate at a flying height of 80-150m above the forest canopy, though this can vary depending on the terrain. Flying at this height enables the bait to fall consistently and predictably from the under-slung spinning buckets, in keeping with their calibration.

Two temporary platforms and gantries were installed at a site in Mason Bay to load bait into helicopter buckets for sowing.

These structures were carefully designed to minimise environmental impact—sitting on the ground with minimal disturbance to the soil. Before installation, the site was assessed for cultural, historical, and ecological values. The impact assessment clearly outlined the actions to be taken to support this operation, including siting the temporary platforms strategically within the historic airstrip footprint to minimise native vegetation disturbance.

The gantries were removed immediately after the operation was completed.

While ZIP has had success delivering predator eradication across large sites in South Westland and Aoraki/Mount Cook, each environment presents its own challenges. Rakiura is no exception. These well-established methods will need to be adapted to suit Rakiura’s unique ecological and operational complexities.

One key point of difference is that ZIP hasn’t previously tried to eradicate Norway or kiore rats, both of which are present on Rakiura. There is a need to understand how effective the tools and methods are with these two species of rats.

The wider suppression area was treated in keeping with the standard method for predator control across Aotearoa: one application of non-toxic prefeed, followed by one application of toxic bait at a target rate of 2 kg/hectare.

In contrast, the eradication trial used the two-phase approach developed by ZIP in Predator Free South Westland:

• Phase 1: Two applications of non-toxic pre-feeds followed by one application of toxic bait at a higher target density—4 kg/hectare—to knock down about 95% of rats and possums.

• Phase 2: Repeats the same series of applications as Phase 1, but with a lower target bait density—2kg/hectare, as there are less predators present—to target any remaining individuals.

A key difference between an eradication approach and a suppression approach is the way that bait is applied. In the eradication trial, for both phases, helicopters applied bait in swathes that overlapped up to 50% to ensure full coverage with no gaps. In the suppression area, overlap was just 20 metres of the effective swath—a much smaller percentage.

Another difference is bait type. The eradication trial used orange-lured bait in Phase 1 and cinnamon-lured bait in Phase 2. This switch in bait type helps overcome bait shyness, encouraging surviving rats and possums to consume bait in the second application round.

Read more about the design of the eradication trial

The ~6,500-hectare trial site within the Rakeahua Valley/Doughboy Bay area was selected because it met several important criteria:

1. It includes a variety of habitats, from lowland forest to subalpine tussock.

2. Existing infrastructure—tracks, traplines, huts, and bivvies—makes it accessible for installing and maintaining the intensive detection networks required.

3. Its inland location makes it possible to treat the entire area without exclusion —essential for an eradication trial.

After aerial application, many pellet baits will be eaten by the targeted pests (possums and rodents). Any uneaten bait pellets begin to break down naturally, through exposure to moisture in the environment — especially rainfall. When operations are delivered in wet winter or spring conditions, the baits break down more rapidly.

These pellets are mostly made of compressed cereal, so when they get wet, they quickly lose their structure—sometimes within just a few hours, though in some conditions this process can take longer. When the baits are exposed to water, the 1080 in the bait dissolves and leaches from the bait into soil, and the toxicity of the bait is rapidly reduced - even if the bait itself remains intact.

Once in the soil, 1080 continues to break down. It moves with water through the soil and becomes increasingly diluted. Microorganisms present in soil also play a key role in breaking it into parts and eliminating toxicity. Temperature is an important influence on how quickly this occurs – the biodegradation of 1080 is faster under warmer conditions (20°C) but still occurs at 5°C.

Bait remaining on the ground becomes non-toxic once it has been exposed to 200mm of rainfall. In the absence of dilution by rain, residual 1080 in bait reaches undetectable levels within about 100 days.

How 1080 breaks down in soil and water (OSPRI)

Every environment is different – alongside the operation in 2025, ZIP is undertaking monitoring to better understand how quickly cereal baits lose their toxicity in Rakiura’s conditions.

Risk assessment is a critical component of gaining approval to use 1080 and other toxins for predator suppression. Part of the permission process requires an assessment of potential environmental effects, including potential effects on non-target species. The application must include a plan of actions to mitigate adverse effects when a significant risk is identified.

As part of the planning and preparation for this application, DOC and ZIP reviewed existing scientific literature and consulted with experts to understand the potential risk to native animals and non-target species that may be present in the area.

Based on knowledge gained from the outcomes of operations elsewhere, mitigations are already embedded within the regulatory framework and operational procedures for aerial toxin use. For example, toxic cereal baits are dyed green and scented to deter birds, helping to reduce the risk of non-target uptake.

By controlling key predators, our goal is to improve the overall survivorship and breeding success of the pukunui population.

Pukunui primarily feed on live or recently dead invertebrates and occasionally small fish, making it highly unlikely that they would ever consume cereal baits. While a potential risk of secondary poisoning exists—via invertebrates that may have ingested 1080—this risk was considered extremely low. Existing research indicates a very low risk of secondary 1080 poisoning for insectivorous species. To date, there are no recorded incidents of waders being harmed during cereal bait 1080 operations.

Several studies have been carried out on the effect of 1080 on invertebrates, and their findings are summarised below by Eason et al (2013):

“...large invertebrates can eat both cereal and carrot bait (Spurr and Drew 1999) and indicates that 1080-poisoned carcasses are less important than direct consumption of 1080 baits for invertebrates. However, in either case, the window of opportunity for 1080 transfer from insects to insectivores is likely to be short-lived. These studies indicate that if invertebrates are contaminated by eating 1080-poisoned carcasses, they will void [excrete] the toxin over a few days and the risk of tertiary 1080 transfer to insectivores will be limited. These field and laboratory results for invertebrates show that 1080 is consumed by some invertebrate species, and therefore a risk of secondary poisoning exists. However, the persistence of 1080 in insects is short-lived, and thus the risk to insectivorous birds or other predators is confined to a short period after sowing poison baits. While there is a theoretical risk from carcasses via invertebrates to birds or other predators, previous field monitoring of invertebrates and birds has shown that long-term population effects on non-target birds and invertebrates, via both primary poisoning from baits and secondary poisoning from 1080-poisoned carcasses, is unlikely (Spurr 1994, Spurr & Drew 1999).”

Based on the assessment above, the risk to pukunui from this operation was considered to be low and significantly outweighed by the benefits of removing key predators.

A study on koura/freshwater crayfish (Suren & Bonnett 2006) shows rapid elimination of 1080 even under artificial exposure to amounts of bait much higher than is realistic for an aerial operation. 

Based on the levels found in this study; to reach a lethal dose a human weighing 85kg would need to consume 40kg of koura tail meat in one sitting. A similar study on tuna/eels (Lyver et al. 2005) found negligible 1080 residue in their tissues.

It is very uncommon for dead native birds to be found after an operation, as effects on non-target species are typically extremely low. However, we do actively seek to understand any unintended effects of predator control activities.

One ngirungiru/tomtit was found after the Phase One operation, and independent testing by Manaaki Whenua confirmed the presence of 1080.

Most research on 1080 to date has focused on its behaviour in flowing water, where the toxin rapidly dilutes and breaks down. While less research exists specifically for boggy or still-water environments, some useful insights are available.

1080 is highly water-soluble and breaks down through dilution and microbial activity. In flowing water, this process begins within hours. In slower-moving or stagnant environments such as bogs, breakdown is slower due to reduced water movement and, in some cases, lower oxygen levels. However, the toxin still degrades over time in these conditions.

Studies with freshwater species like koura/freshwater crayfish and tuna/eels have shown that while these animals can absorb 1080 (e.g by eating bait or scavenging poisoned animals), the toxin is processed and cleared from their systems within a few days, with no lasting harm observed.

While more research would be valuable for bog-specific environments, decades of monitoring and trials suggest that 1080 poses minimal risk to freshwater species, even in slower-moving or stagnant water.

In most cases, carcasses remain where animals die and decompose quickly. However, carcasses may enter waterways or wash out to sea following a 1080 operation, particularly after a storm event. On occasion, carcasses may also wash up on beaches, where they can pose a risk to scavenging animals, such as dogs, through secondary poisoning.

1080-poisoned carcasses do contain residual toxin for a time as they degrade. ZIP’s trials have shown an 80% reduction in residual toxicity in a rat carcass within 14 days of death. The poison’s persistence in carcasses is long enough to pose a hazard to scavenging animals on land, which is why we can use secondary poisoning to target feral cats. 1080 is rapidly diluted and biodegraded once it enters water.

Fish, invertebrates, and water quality have remained essentially unaffected even in areas with extensive 1080 use. There is no recorded case of 1080 contamination in commercially harvested seafood.

From the research undertaken to date, the risk of commercially valuable fish like blue cod or crayfish finding, consuming, and retaining harmful levels of 1080 from a poisoned carcass that drifts into the ocean is considered extremely low

ZIP has initiated a research programme to better understand any potential risks 1080 may pose to marine environments and species. This work is being guided by a project team including representation from the Ministry of Primary Industries, DOC, and the wild catch and marine farming industries. The trials themselves will be conducted by Cawthron Institute.

The first step is a laboratory trial to determine how 1080 behaves and breaks down in seawater. While there is a reasonable body of research on 1080 in freshwater systems, very little is known about its persistence or degradation in marine environments. Establishing this baseline is essential to understanding whether there are any unique risks in saltwater.

ZIP, on behalf of a collaborative project team including DOC, the Ministry of Primary Industries, and representatives from the wild catch and marine farming industries, has engaged Cawthron Institute to undertake scientific trials involving 1080 and sea water.

This research is still in its initial phase, with the analytical method now developed. The first series of trials is measuring the diffusion of 1080 from cereal pellets in sea water.

We will share the results of this trial publicly, once completed. The project team will use these results to inform the next steps for this research stream.

Morepork are unlikely to be killed by ingesting 1080, as they generally eat live prey. A total of 47 radio tagged morepork have been monitored through six different 1080 operations and none died from poisoning.

While there is some risk to individual native birds from consuming 1080, this risk is well understood and managed. At a population level, native birds greatly benefit from predator control.

The greatest threat to native birds on Rakiura is predation by rats, feral cats and possums, which prey on both adults and chicks. Removing these predators will lead to significant increases in bird fledgling survival rates, as shown by extensive evidence from across the country.

The lethal dose of 1080 for a wētā is more than 30 times that required to kill a Norway rat[1]. Therefore, wētā are quite resilient.

In a 1993 laboratory study, 12 tree wētā, or tokoriro, were fed 15 micrograms of 1080 per gram of body weight. All survived. Their eventual post-mortems found that the insects had eliminated 67 per cent of the 1080 within one to four hours, and 90 per cent of it within four to six days[2].

In 2000, researchers investigated any effects of 1080 on wētā and other invertebrates in Tararua Forest Park. Very few wētā were observed on baits at night, and cave wētā collected alive from baits were found to have consumed less than 10 per cent of the average lethal concentration. Invertebrate numbers were monitored for 12 months before, and four months after bait application, which had no significant impact on the numbers of either Wellington tree wētā or cave wētā, nor on slugs, spiders, and cockroaches[3].  

Rodents present a far greater threat to wētā than 1080: in a 2005 study, they were found in 76 per cent of ship rat stomachs[4].

Hourly counts of wētā ‘stridulations’ – the scratching sound they make with their rear legs – before and after a 1080 operation in Waipoua, Tai Tokerau, in 1990 recorded more wētā post-operation[5].

After rats and mice were eradicated from Maungatautari fenced sanctuary in 2004, detections of tokoriro, increased 12-fold, and detections of ground wētā 52-fold. In this and other studies, removal of rodents saw increases in the percentage of adult wētā by up to 36 per cent—including females, which are most vulnerable to predation.

[1] Rammell and Fleming,1978. Compound 1080: Properties and Use of Sodium Monofluoroacetate in New Zealand, Animal Health Division, Ministry of Agriculture and Fisheries, New Zealand

[2] Eason et al., 1993. The fate of sodium monofluoroacetate (1080) in water, mammals and Invertebrates.

[3] Spurr and Berben, 2004. Assessment of non-target impact of 1080-poisoning for vertebrate pest control on weta (Orthoptera- Anostostomatidae and Rhaphidophoridae) and other invertebrates in artificial refuges.

[4] Innes, 2005. Ship rat. In: King, CM ed. The handbook of New Zealand mammals. 2nd edn. Melbourne, Oxford University Press. Pp. 187–203.

[5] Pierce, R.J. and Montgomery, P.J., 1992, The fate of birds and selected invertebrates during a 1080 operation, Science and Research Internal Report No. 121, Department of Conservation, Wellington.

DOC and ZIP are using trail cameras to measure the pre- and post-control populations of feral cats, three species of rats, possums, and white-tailed deer. The exact timing of camera checks will depend on weather conditions and other logistical constraints.

A network of trail cameras has been established in grids across a range of habitat types from the foreshore to the top of the Tin Range. Camera grids are designed in a density appropriate to the known home ranges of target species, with the densest grids established to monitor kiore in the eradication trial area.

Deer monitoring is being carried out using trail camera grids in deer repellent and non-deer repellent areas, and in a non-treatment area. The aim is to better understand to extent to which deer repellent reduces the impact of 1080 on the white-tailed deer population on Rakiura and to learn whether deer repellent reduces the effectiveness of the bait on the three target rat species. This will be valuable research for Predator Free Rakiura. 

DOC will continue to monitor feral cats post-control operation to better understand how long it takes for feral cats to reinvade the treated area. Because of this, feral cat monitoring will run into 2026.

We expect that it will take at least one month after the application of toxic bait to accumulate meaningful data about the results of the operation. When we have the information, we will share the results of monitoring with the Rakiura community.

Lures are used at trail camera stations to attract predators like rodents, possums, and feral cats into the camera’s view. Without a lure, animals might pass nearby but not be detected.

To ensure consistency, the same lure setup is used before, during and after the operation. This applies to all predator monitoring. Cameras specifically for monitoring deer are not lured as deer are typically detected incidentally as they move along game trails near preferred food sources.

For ZIP’s trial on rats and possums, an automatic dispenser that releases a small amount of Best Foods mayonnaise daily is used. For DOC's camera network to detect feral cats, rats and possums, wire cages containing fresh rabbit meat along with two long-life rabbit-scent lures underneath are used. Due to the difficulty of identifying the difference between rat species in camera footage, DOC has also installed a rat kill trap network to measure the success of the operation on ship rats, Norway rats and kiore.

To track the success of the Pukunui Recovery Project, DOC carries out annual counts of pukunui at three key winter flocking sites each year. These counts take place as the birds flock together in known locations prior to the breeding season. These annual flock counts show both short-term changes (from year to year) and long-term population trends – giving us a clear picture of how the pukunui population is doing over time.

Increases in pukunui numbers over time —meaning more young birds are surviving and joining the population than adults are dying— are used as an indicator that predator control efforts are effective at reducing predation to improve breeding success.

Year-to-year changes in pukunui numbers are largely driven by adult, egg and fledgling predation during the breeding season. Feral cat predation is a major cause of decline.

Feral cats roam large distances and can be wary of the traditional methods to control them – trapping, hunting and bait stations. There are limited tools available to control feral cats across large areas.

Predator control is only undertaken in a portion of pukunui breeding habitat. Breeding habitat is patchy and includes sites across the full length of Rakiura. To save more dotterels, more habitat needs to be protected.

Long-term solutions for the pukunui population require landscape-scale change – this is why initiatives such as Predator Free Rakiura are so important. In the meantime, the focus remains on effective predator control to hold the line and prevent extinction.

Yes—DOC considered all available options.

New technology may offer alternative methods in the future, but at present, aerial 1080 is considered the most effective method to protect pukunui because it enables control of feral cats on a landscape scale, which is required to effectively protect core pukunui breeding areas.

Ground-based trapping and hunting have been used and can be effective at a local scale, but they also face significant limitations:

• Feral cats are highly mobile, capable of travelling long distances, learning to avoid devices and reinvading areas where control has taken place.

• Much of the pukunui breeding habitat is remote and steep to access on foot, limiting the success of ground-based control.

• Ground-based control is resource-intensive, dependent on staff availability, challenging terrain, complex logistics.

In response to the fluctuation of the pukunui population, DOC has increased its investment in protection measures, including additional staffing and expanded predator control. DOC remains committed to building on these efforts to provide the strongest possible protection for this vulnerable species.

The aerial 1080 operation is a critical step forward in protecting pukunui, because it will enable:

• Aerial bait to be delivered across large, continuous areas, minimising gaps in predator control and reaching terrain that is otherwise inaccessible.

• Targeted control of feral cats through secondary poisoning, this approach relies on them scavenging poisoned rodents and/or possums

An aerial approach allows for landscape-scale control of multiple predators in one operation targeted to disrupt feral cat predation—critical to halting the decline of pukunui and enabling long-term recovery.

It isn’t too late but the situation is critical. The aerial 1080 suppression operation is a crucial intervention to give pukunui a fighting chance while we work toward a predator-free Rakiura.

The population has declined rapidly in past years, with 105 birds remaining. We don’t have the luxury of time— by delaying action we would risk losing even more individuals this breeding season.

In 2011, DOC postponed a planned aerial operation in the Dart Valley due to community concerns. The result was the largest mohua population crash recorded at this site. It took more than a decade for the mohua population to recover with sustained predator control operations during beech mast years—and they narrowly avoided local extinction.

It’s hard to have perfect foresight in conservation. But at times, the risk of inaction outweighs the risk of continuing with current methods. This is the point we’ve reached with pukunui - the risk of extinction is too high not to act now.

No—there is very low risk to people from airborne dust or bait particles during aerial 1080 operations.

The greatest potential for airborne exposure to 1080 dust is at the load site. To manage this risk, workers wear personal protective equipment and bait manufacturing standards are designed to meet strict Worksafe exposure standards for dust.

Research into short-to-long term health risks associated with either significant or minimal 1080 exposure is well documented. The majority of this risk assessment focuses on people preparing or using the toxins, as they are exposed to the highest concentration forms of the toxin more regularly, primarily in the form of dust/residue.

Worksafe have an exposure standard for 1080 airborne particulate of <0.05 mg/m3 (50 μg/m3) per day, which must be maintained on aerial operation sites at all times to ensure the welfare of those handling the toxin. Exposure at these levels has not been found to have any effect on human health.

Three studies have investigated how much dust might be in the environment after three 1080 operations. Researchers detected very low levels of 1080 outside the treatment area, indicating relatively little dust drift had occurred, and well below levels that would pose a risk to human safety either through acute or chronic exposure.

Te Whatu Ora – Ministry of Health and the Public Health Unit has stringent safety regulations around aerial 1080 operations, including considerations around the risk of dust associated with the operation.

Yes, but hunters are advised that an eight-month caution period applies, during which the commercial harvest of game animals is restricted, and hunting for personal consumption of meat is not recommended. 

Animal carcass monitoring stations were set up at three sites for both Phase 1 and 2. They are first checked four months after the application of toxin, which is the minimum caution period, and then regularly until carcasses have fully broken down. Once soft tissue is gone and only bones, skin and fur remain, the is caution lifted. If bait and carcass degradation is faster than estimated, then the caution period may be reduced. However, it will not be shorter than the four-month minimum caution period under the New Zealand Food Safety Authority requirements for 1080.

To see areas where a caution period is active, refer to the DOC Pesticide Summaries.

Alongside engagement with other key stakeholder groups, we’ve had ongoing discussions with representatives from the NZ Deerstalkers Association, Game Animal Council, local White-tail Management Group, and other local experienced hunters to understand the concerns of the hunting community and incorporate their knowledge into our operational design.

We have taken several actions as a direct result of these discussions:

• Hunting blocks remained open for bookings throughout operations, with appropriate communication with hunting parties and recommendations in place not to consume meat until caution periods are lifted.

• We have been running a trial observing white-tailed deer encounters with ProDeer (deer repellent) and ProNature (non-deer repellent) bait, using hand placed baits in front of cameras. This trial was designed by Manaaki Whenua and implemented by ZIP.

• Deer repellent was used within bookable hunting block boundaries. Non-deer repellent bait was used in the open hunting zone, including across pukunui breeding grounds.

• Deer monitoring is being carried out using trail camera grids in the deer repellent and non-deer repellent areas, and in a non-treatment area. The aim is to better understand the extent to which deer repellent reduces the impact of 1080 on the white-tailed deer population on Rakiura and to learn whether deer repellent reduces the effectiveness of the bait on the three target rat species. This will be valuable research for Predator Free Rakiura.

• On the advice of experienced hunters, the deer monitoring areas moved to the Doughboy Bay area. This changed the location of the 1080 to Zero eradication trial area to the Rakeahua Valley area where we understand there is typically less hunter activity.

• The operational boundaries changed on the eastern side of the original operational area to completely avoid some of the bookable hunting blocks.

Individual hunters and hunting parties with bookings in the blocks within or adjacent to the operational area were contacted directly, to understand, discuss and manage any potential effects on their hunting activities.

A caution period is the designated timeframe after an aerial 1080 operation during which:

• Commercial harvest of game animals is restricted, and

• Hunting for personal consumption of meat is not recommended.

This period allows time for any bait and animal carcasses to fully break down and eliminate the risk of toxin exposure. Caution periods are set by the Ministry of Primary Industries as part of their food safety regulations. The minimum period is four months.

After that, we monitor the breakdown of bait and carcasses in the environment. Once they’ve sufficiently broken down, and with DOC’s approval, the caution period can be lifted. In wet environments like Rakiura this breakdown is likely to happen relatively quickly, so we could expect to lift the caution period within four to six months.

In response to interest from the Rakiura community and others, an agreement was made to test for 1080 residue following aerial 1080 operations involving toxic bait application.

For Phase 1, water samples were taken from the Rakeahua River, just before it meets the sea. All results returned negative for 1080.

For Phase 2, water sampling was carried out at both Rakeahua River and Doughboy Creek, just before each meets the sea. Samples were collected at four intervals: before bait application (as a control), and then 2 hours, 8 hours, and 24 hours following bait application. All samples were immediately frozen and sent to Manaaki Whenua – Landcare Research for analysis.

• All Phase 2 samples tested negative, except for two samples taken 8 hours post-application, which showed trace levels of 1080 just above the detection limit.

• Upon re-testing, both of the 8-hour samples returned negative results for 1080.

• The initial trace readings (0.17 ppb and 0.16 ppb) were 11.5 times lower than the Ministry of Health’s safe limit of 2 ppb for drinking water.

With no persistence detected and all other samples returning negative results for 1080, there is no risk of contamination or toxicity to the aquatic environment.

No, monitoring of marine species was not carried out during this operation.

Following consultation with the commercial wild catch and marine farming industries, we committed to not sowing toxic bait into the sea during the operation to protect pukunui in 2025. If this condition was met, these parties agreed that marine species monitoring was not required before or after this operation.

We have been working closely with nominated representatives from both the wild-catch and marine farming industries to design and implement operations and research that respond to their questions and concerns about work to remove predators from Rakiura.

In response to requests from these industries, several measures were in place for operations in 2025:

• No toxic bait was sown into the sea during this operation. ​

• Using ZIP’s safeline approach, a buffer from the coastal area was implemented to minimise the risk of bait entering coastal waters.​

• The operation was conducted from a loading site on land, rather than from a vessel at sea.

Aerial brodifacoum was not used in this operation.

Beyond the operation to protect pukunui in 2025, we continued to work with wild catch and marine farming representatives to respond to their questions about how 1080 behaves in the marine environment.

ZIP has initiated a research programme to better understand any potential risks 1080 may pose to marine environments and species. This work is being guided by a project team including representation from the Ministry of Primary Industries, DOC, and the wild catch and marine farming industries. The trials themselves are being conducted by Cawthron Institute.

The first step is a laboratory trial to determine how 1080 behaves and breaks down in seawater. While there is a reasonable body of research on 1080 in freshwater systems, little is known about its persistence or degradation in marine environments. Establishing this baseline is essential to understanding whether there are any unique risks in saltwater.

The next phase of research will be shaped by the results of this initial trial, which is underway now. Results will be made publicly available once this research is complete. 

Collaborative discussion and research over the next year will continue to inform the design of future operations.​​

The operation to protect pukunui was a suppression operation, rather than an eradication operation. Rodent populations typically rebound much faster than feral cats following a suppression operation, because they breed multiple times a year. Prey-switching, where predators like feral cats change their food source, is unlikely to be an issue in this context.

Under the Predator Free Rakiura programme, the long-term goal is to completely remove both feral cats and rats in a coordinated manner. By eliminating both predator species simultaneously, we expect to further reduce the risk of prey-switching and better protect vulnerable native species such as pukunui.

The cereal bait containing 1080 is consumed by the rats and possums, and then the feral cats eat the rat and possum carcasses. The bait itself isn’t palatable to an apex predator, so it works through a vector process.

We know that secondary poisoning with 1080 is an effective method for targeting feral cats here on Rakiura. A 2003 ground-based operation by DOC around Mt Anglem/Hananui used 1080 in bait bags and successfully removed 10 out of 11 feral cats.

Yes, 1080 sausage baits were considered; however, they are still in the trial phase and have not yet been registered for full operational use.  We remain confident in achieving a strong feral cat knockdown through secondary poisoning, a method that has proven effective in previous operations.

It’s also worth emphasising that this operation isn’t just about protecting pukunui. Native bird numbers in the operational area are noticeably low compared to places like Oban where regular trapping occurs. By reducing possums, rats, and feral cats, the predator control operation will support the recovery of the entire ecosystem. With fewer possums browsing trees, there will be an improvement in overall forest health through a healthier forest canopy. Birds, insects and lizard species will also benefit from a reduction from predators and food competitors. This broader restoration outcome would not be achievable through feral cat control alone.