1080 | Protecting New Zealand's unique birds

1080 poisons mammals, and its use is widespread in New Zealand’s backcountry.

Poison? Why?

After all, 1080 is either restricted in use or outright banned in most other countries. New Zealand uses around 80% of worldwide production. Here we scatter it from helicopters in national parks and other conservation land.

The reality is that 1080 kills introduced mammalian predators in a targeted way and is quickly broken down by bacteria and algae into non-toxic components.

The devastation of our vulnerable birdlife might be forever.

What is 1080?

Sodium fluoroacetate, or 1080, as it became known after it was tested as a new rodenticide in the USA in 1944, is a water-soluble organic compound. It is naturally occurring in many plants around the world. The research is extensive, with more than 1,400 scientific papers written over the last 70 years on the toxicology, soil microbiology, and avian ecology.

It is highly toxic to mammals, killing them within hours of eating it. The target species in New Zealand are all introduced predators: rats, possums, stoats, and feral cats that prey on native birdlife and damage forests.

Why is 1080 used?

New Zealand is a series of islands that evolved in isolation, with birds filling ecological niches of mammals in other land masses. There are five big reasons why 1080 is used here.

1. Size. New Zealand is way bigger than you might think. It is larger than the UK and comparable in size to Colorado or Michigan. New Zealand public conservation land administered by DOC covers almost a third of the country, an area bigger than Ireland or South Carolina. Much is mountainous and remote, with few roads and poor access except by helicopter.

2. Bats! Our only native land-based mammals are two species of small bats (one insectivorous, the other highly localised and non-targeted). Both are endangered.

3. Predator arrival. Due to the lack of native predators, New Zealand birds, insects, and reptiles have not developed defences against introduced predators. Stoats, rats, feral cats, and possums have caused devastating losses to many bird species. Twenty species of endemic birds are now extinct after Europeans, along with the new predators, arrived in New Zealand about 250 years ago. Other species that were once plentiful on the mainland have only survived due to having been relocated to predator-free offshore islands or fenced sanctuaries, including Kākāpō, Saddleback/Tīeke, Stitchbird/Hihi, Kākāriki, Mōhua, Kōkako, and Little Spotted Kiwi. Each of these species shares a common vulnerability: they evolved without mammalian predators, so they forage on the ground, nest low, or don’t have natural predator-avoidance behaviour.

4. Beech mast. Mast is an old word that describes acorns falling and being used for animal food over winter. In New Zealand, it is a natural phenomenon where most years beech trees, the predominant trees in South Island forests, produce few seeds, but every few years following a good summer, a vast amount of seed is produced. Because of the better food supply, rat and mouse populations rise exponentially, but when the seeds are eaten or rot, the increased number of rodents turn to birds as a food source.

5. 1080 is water soluble. 1080 is easily dissolved in rain or stream water and can then be quickly broken down by bacteria and algae to produce non-toxic components. 1080 doesn’t build up in the environment.

New Zealand birds are vulnerable to predators

Many birds are flightless or don’t fly well. Kiwi, takahē, kākāpō, and weka are easy prey for feral cats or stoats.

Some birds learned to freeze when bird predators were around before the mammals arrived. The mammalian predators rely on smell to find their prey.

Birds don’t breed prolifically, and some have flightless chicks in a nest for 45 to 60 days.

Stoats and rats are skilled climbers.

Many birds nest in holes in dead trees that don’t have a secondary exit.

Predators, including feral cats and wild dogs, kill more birds, lizards, wētā, etc, than they need to survive. A single dog killed about 500 kiwi in Waitangi Forest over six weeks in 1987. A single feral cat killed 107 endangered short-tailed bats in one week.

Some birds are less vulnerable

Bellbirds and some other species can survive because they have open nests high in the treetops and can fly off if a predator approaches. They produce many eggs when food is plentiful and can produce four clutches in a single season with 2 to 4 eggs per clutch.

Other species have rapid development of their young, so they spend little time trapped in a nest. Fantail eggs hatch after 14 days, and fledglings leave the nest 14 days later. Pairs of fantails can raise five broods in the summer.

But many species are vulnerable because they nest in tree cavities with no escape route, which makes them and their eggs easy targets for stoats or rats.

Rats, stoats, feral cats, possums, and mice

European settlers brought a number of animals with them to remind them of home. Rabbits were introduced for gentlemen to hunt, but without predators, the rabbits did what rabbits do, and bred prolifically. To deal with the rabbit plague, ferrets, stoats, and weasels were released and provided some control, but also hunted native birds. Other predators, possums for the fur trade and hedgehogs, were released. No foxes, fortunately. Seven species of deer, pigs, goats, chamois, and Himalayan tahr are herbivorous, but do considerable damage to the forests and alpine areas. Abandoned cats became feral. Two species of rat, along with mice, jumped ship to join the smaller, less voracious kiore that had been introduced by Māori from Polynesia.

Rats. Rats are omnivores with prolific breeding cycles when food is plentiful. They are smart, resourceful, and agile climbers that can get to the treetops to raid birds’ nests during breeding time. They are hunted and eaten by stoats. Range widely.

Stoats. Stoats are carnivores with a high metabolism that requires eating 25 to 30% of their body weight a day. They can kill birds four times their size, such as kiwi, kākā, and whio. They kill more than they require for food. Range widely.

Feral cats. These are solitary and target adult breeding birds that nest on the ground, as well as rats and stoats. Range widely.

Possums. Possums consume canopy foliage in a wasteful manner, while opportunistically killing nesting females, their fledglings, and eggs. Have a limited territory with about an 85 m radius, so need a large number of traps.

Mice. Mice multiply prolifically during beech seed mast seasons, while also eating eggs and invertebrates. These provide plentiful food for rats and stoats. Also stay close to home.

Big South Cape Island bird extermination

Rats were given free rein in a new environment when they arrived in late 1963 on the previously predator-free Big South Cape Island, located 2 km from the southwest tip of Rakiura. The rats quickly decimated the endemic birdlife, the last remnants of the species. Three species became extinct in a few months. The once widespread South Island Tīeke was reduced to 36 individuals, and 24 were relocated to nearby predator-free islands. Away from predators, their numbers have increased to over 2,000. This is a similar story to what happened with the last individuals of the Black Robin, the Takahē, and the Kākāpō.

Conclusion from this story: If rats, stoats, feral cats, and possums are allowed to breed uncontrollably and their numbers increase, birdlife numbers will continue to diminish, and more endemic species will become extinct.

Kāpiti Island predator eradication

The Kāpiti Island experience shows the limitations of trapping to eliminate predators on a large scale. Although it is just 1,965 hectares (4,856 acres), it took six years to eliminate the estimated 20,000 possums. In the initial two years, private trappers managed to remove about 75% of the possums. Then, after 450 km+ of tracks and 1,500 traps were established, contracted trappers monitored them and removed another 4,000. It took another two years with experienced trappers and three dog teams to track down the last 48 possums. That meant setting, checking, and re-baiting those 1,500 traps thousands of times across steep terrain over two years to clear those remaining 48 possums.

Traps were not considered for rats on Kāpiti Island, as they would reproduce faster than they could be caught. Instead, brodifacoum rat poison baits were dropped across the entire island by helicopter, including the areas of inaccessible bluffs. Brodifacoum takes many days to kill rats, so the rats don’t associate the baits with danger, allowing 100% elimination. Unlike 1080, it is not easily broken down, so secondary and tertiary kills are common (rats eating dead rats).

Private boats are not permitted to land on the island, and all tourist and DOC boats are thoroughly checked for pests before leaving the mainland. Despite that, a stoat was sighted in 2011, and a major eradication program costing $200,000 was undertaken that found three male stoats.

Kāpiti Island is now a significant bird sanctuary and has vulnerable, endangered birds thriving there. It’s harder to see how this protection method could be extended to larger areas of the mainland, other than fenced sanctuaries where possums and rats could just reinvade from outside the protected zone.

Conclusion: Trapping on 1,965 hectares of Kāpiti Island was a time-consuming, labour-intensive, and financially expensive operation. Trapping doesn’t scale for the preservation of species on the mainland. Fiordland National Park is about 1,260,700 hectares (4,868 square miles), 641 times larger than Kāpiti Island, and larger than Yellowstone and Yosemite National Parks combined.

Use of 1080 in NZ

1080 was first imported into New Zealand in 1953 and used to kill rabbits on agricultural land the following year. Two years later, it was used to kill possums, which were spreading bovine tuberculosis to farm animals. The techniques were soaking chopped carrots in 1080, then dropping up to 30 kg/hectare of bait from fixed-wing aircraft, which meant anywhere from 20 to 50 g of 1080 were distributed per hectare. Saturation bombing, but with no pre-feeding. This caused considerable deaths among small native birds and curious kea.

Now it is added to cereal pellets that weigh either 6 g (0.21 oz) if targeting rats and stoats, with 9 mg of 1080 per pellet, or double that if targeting possums.

The bait is spread from GPS-controlled helicopters that drop 1 to 2 kg of bait per hectare, with around 1.5 to 3.0 g per hectare of 1080. The cereal pellet is 99.85% cereal grain flour and sugar, with green vegetable dye to discourage birds and cinnamon scent, which is attractive to mammals but repels birds.

This rate is about 4 to 6 thumb-sized pellets on a full-size tennis court.

Helicopters deposit the cereal pellets without poison a few days before the baits with 1080 are dropped to accustom rats and mice to eating the pellets.

Helicopters use digital maps of the treatment areas to program a precise route to ensure complete coverage. Watercourses, with 20 to 100 m buffer zones, are mapped out as strict exclusion zones. The baits are dropped from a specialised GPS-controlled sowing bucket with a rotor to distribute the pellets, with an auto cut-off once the exclusion zone is near. It only resumes distribution when the helicopter gets back into the designated drop zone.

Regulatory overview

Aerial 1080 drops are not spontaneous decisions and are among the strictest regulated environmental operations in the world. This typically takes 12 to 18 months from initial planning to the helicopter drop.

Each operation needs to be signed off by:

Public Health Officers (Health NZ/Te Whatu Ora): Issue statutory permissions to safeguard human and municipal drinking water catchments with mandatory stream buffer zones.

Department of Conservation (DOC): Evaluates environmental effect assessments, sets species-protection protocols, and issues land-use permits for conservation land.

Regional Councils: Ensure compliance with national environmental standards and regional soil and water discharge rules.

The EPA (Environmental Protection Authority): Enforces strict hazardous substance controls, setting bait concentrations and national label rules.

WorkSafe NZ & MPI: Audits workplace/pilot safety, controlled substance licensing, and animal welfare requirements.

Mana Whenua & Landowners: Formal engagement and partnership with local hapū/iwi and neighbouring property owners.

Water in the area and downstream is monitored. Thousands of water samples have been tested over decades, and 1080 is very rarely found in streams, but trace 1080 is below the safe drinking threshold of 3.5 parts per billion. Hut rainwater collection systems are blocked up and checked to avoid rainwater tank contamination, with large water containers flown into huts for trampers.

Why 1080 and not something else?

1080 is used because it doesn’t linger in the environment. Plants don’t store or accumulate 1080, and can quickly metabolise any that their root system absorbs.

Insects that eat bait die within hours, or if they survive, it is quickly metabolised or excreted.

1080 is highly soluble in water, and stream turbulence breaks up the cereal pellets and dilutes the toxin quickly. Bacteria and algae consume 1080 as food and metabolise it into non-toxic components. If it lands on the forest floor, rain leaches the 1080 out of the cereal pellet into the soil, where bacteria and fungi metabolise it all in weeks. It is true that 1080 can remain in the pellet if no rain falls.

Rat poison, brodifacoum, is not as biodegradable, being fat and not water-soluble, persisting in the soil for a year or more. It can remain in liver tissue for months. It works quite slowly, taking 3 to 10 days to kill a rat, which is why it is 100% effective due to secondary and tertiary kills. But if carnivorous birds, ruru/morepork, weka, hawks or falcons eat a dead rat, they can also die.

Biological predator control measures, while technically possible, could spread and kill similar species in other countries, such as possums in Australia, where they are a protected species.

Trapping!

Traps are useful to maintain boundaries near population centres with reliable populations of volunteers, and 1080 use is not feasible.

Trapping relies on volunteer labour to clear dead predators, and this generally only reduces numbers. They are not very effective when rat and stoat numbers boom. Traps are less effective with low predator numbers, as there is less competition for food. During a beech mast event, when rat and stoat numbers explode, there is a massive amount of beech seed available at the very time you want traps to work.

Thousands of steel traps inside wooden boxes have been located alongside tracks, usually near population centres, so they can use volunteer labour to clear the catch and rebait the box. It’s been found that if the box has two traps, it usually catches a second predator after they come to investigate the first. However, many, if not most, traps never catch anything. And disillusioned volunteers may become discouraged if their efforts are not successful. In many instances, since they are serviced by volunteers, traps often only get sporadic maintenance, and not necessarily when stoats are seeking new territory.

Traps that can reset automatically 24 times and use a lure that lasts six months were a hopeful advance, but they haven’t proved that in practice. Rats and stoats are highly sensitive to the plastic odour of these traps and their smooth textures. The plastic tends to retain human oil and skin scent, which predators avoid.

But while possums are curious, rats learn from a near miss and then avoid traps or baits. Stoats may also be curious, but only if they see a clear exit. They can be reluctant to put their head in a trap. Rats, on the other hand, are very risk-averse and extremely cautious about new objects in their territory.

Wangapeka River whio (Blue ducks)

The Wangapeka River and tributaries in Kahurangi National Park have around 500 traps along the Wangapeka track and valley floor, but these cover less than 10% of the 35,000 ha (86,500 acres or 135 square miles) river catchment. The traps are maintained year-round to protect whio/blue duck. There are fewer than 40 breeding pairs of whio in the 35,000 ha river catchment.

These traps catch from 40 to 80 stoats in an average year and 150 to 250+ in a mast year. 300 to 800+ rats are also caught.

However, from predator surveys using rat and stoat tunnels, the number of rats in the catchment varies from an estimated 100,000 in a non-mast year to 1,500,000 in a beech mast year. The estimated numbers of stoats are 1,000 in a non-mast year to 10,000 in a mast year.

The traps make a difference when predator numbers are low, but offer little protection from predators in plague numbers, which is when you really need them.

1080 issues

The main concerns with 1080 are the danger to kea and dogs. This was more of an issue when first used around kea, where the curious kea would play with the pellets and eat some. New techniques have been developed to minimise this risk.

Dogs are super sensitive and can die months after a drop by eating from undecayed carcasses of poisoned predators: possums and rats. This concerns hunters in particular, as they shouldn’t hunt, or have dogs in an area where 1080 has been dropped, for 4 to 8 months after the event (until possum carcasses fully decompose).

In the early decades, raw 1080 paste formulations like jam baits posed higher handling risks. Modern hard cereal pellets are now dyed bright green, with cinnamon scent to deter birds, and contain bittering additives to prevent accidental human consumption.

The future of threatened endemic birds

1080 is used to help prevent the extinction of some of New Zealand’s most iconic taonga, our national treasures.

When Captain James Cook anchored the Endeavour in Queen Charlotte Sound (Marlborough Sounds) in 1770, he was surprised by the density and volume of the dawn bird chorus coming from the undisturbed native forest. His log entry from 17 January 1770 contains descriptions of pre-European New Zealand birdlife:

“The ship lay at the distance of somewhat less than a quarter of a mile from the shore, and in the morning we were awakened by the singing of the birds; the number was incredible, and they seemed to strain their throats in emulation of each other. This wild melody was truly enchanting, and, though it may appear extravagant, it was certainly the most melodious wild music I have ever heard, almost imitating small bells, but with the most tunable silver sound imaginable…”

We are unlikely to get back to those numbers of birds across the country, but the conservation movement does not want to allow any more species to become extinct and wants the species to retain genetic diversity and a healthy breeding population.

Kāpiti Island shows birds can once again flourish if predators are absent, but we can’t relocate all birds under threat to offshore islands. The mainland must be a viable habitat.

The Wangapeka area shows you need both 1080 and traps to protect vulnerable birds when dealing with the vast and rugged New Zealand landscape.

Doing nothing will end in a Big South Cape Island-type experience: the extinction of unique New Zealand wildlife.

Extinction is so forever.