Brodifacoum – a Lethal Poison Like 1080 – but Much Worse?

by Tony Orman

Government use of 1080 poison in New Zealand is controversial and of all poisons it commands the headlines.

But there is a much worse poison – it is called brodifacoum. Somehow it’s slipped under the radar as the saying goes.

Brodifacoum is widely used by regional councils and government agencies such as the Department of Conservation. Typical of its unknown but fairly widespread use is Ulva Island near Stewart Island where the Department of Conservation is currently undertaking rodent eradication. Incorporated is a further step of “the removal (eradication) of deer from Ulva.”

Ulva Island is small, just 267 hectares and with a coastline of about 11 kilometres.

DoC’s justification for removal of the whitetail deer is “an important step to ensure that deer don’t remove bait during their operation therefore making it unavailable for rats.”

That in itself typifies the illogical, impractical approach by the department.

A longtime conservationist, in an e mail to me, described DoC’s “removal of deer” policy, mentioned in their brochure, as “laughable”. 

 “Firstly – they’ve aerially poisoned with brodifacoum at least twice before – therefore there are virtually no deer left on the island, or a couple at best,” he said. 

 “Secondly – they aerially spread around 30kg of bait per hectare when eradicating, via two or three successive aerial operations, a week or two apart. The baits are usually 6 grams in weight, each. That’s 5000 baits per hectare … and the fools are saying that three deer (if there’s any at all – it’s a small island) need to be removed because they’ll eat a couple of baits that are needed to kill a couple of rats!!!”

“Really, are these people aware of what they’re actually saying, and how stupid they are?”

I have come across brodifacoum poisoning notices in the central North Island when trout fishing, accompanied by my Labrador dog. In one case I asked a farmer why the regional council was using brodifacoum. for possums. He didn’t know and added that possum numbers were very light anyhow.

Because of the extreme danger to my dog, I didn’t go fishing. Besides, trout fishing a river into which poisonous baits may have fallen, leaves a toxic feeling, spoiling what could have been an enjoyable day’s fishing! 

Such cavalier attitude of regional councils – and the Department of Conservation – belies the lethal nature of brodifacoum.


Trout Stream in King Country with brodifacoum warnings


How does it compare to 1080?

Both poisons have a ”withholding period” which means a time must elapse after the toxin’s use before stock can be safely grazed or game animals such as deer, taken for home consumption.

The Ministry of Primary Industries stipulates 4 months for 1080 poison.

For brodifacoum it says “cannot supply carcasses taken from a brodifacoum operational area (including the buffer zone) within 3 years (36 months) of the poisoning terminating.”

Buffer zones represent the area of land between the land subject to a poisoning operation and that free of poison. The buffer zone provides a margin of safety between the poisoned-free area and the possibly poisoned adjoining land. The size of the buffer zone is determined by what is known about normal wild animal migration and movements between areas. 

The extensive withholding time for brodifacoum is due to its known long-term persistence in the environment and animal bodies.

What is brodifacoum?

“Brodifacoum is an anticoagulant poison, which is dyed blue in colour, and reduces the clotting power of blood. It can also be used by landowners to undertake possum and rat control on their own land because a user licence is not required,” says MPI.

Slow, Cruel Death

Brodifacoum is an anticoagulant, which causes the animal to die slowly and painfully from internal bleeding. As cruel as death is by 1080, (which blocks the chemical process of respiration), by brodifacoum it is far more prolonged.

RSPCA Australia says “these poisons are not considered to be humane due to their toxic effects including difficulty breathing, weakness, vomiting, bleeding gums, seizures, abdominal swelling and pain. In addition, the body of the poisoned rodent presents a significant risk if it is eaten by other animals, including native wildlife.”

The “time to kill” factor is relevant.

1080 is a slow acting poison taking hours or days to kill a bird or mammal. 

But brodifacoum is even slower to kill. 

Rodents will usually die from ingesting brodifacoum within 4 to 8 days of their first feed of bait, whereas possums can take weeks to die according to the National Pest Control Agencies.

1080 requires a user to have a licence to use the toxin.

No licence is needed for brodifacoum, for example shop sold rat poison.

Brodifacoum is the basic ingredient in rat poisons sold over shop counters, to anyone, young or adult with no controls whatsoever.

Predator Free NZ says brodifacoum can be bought “online and can be bought at your local hardware shop; may be provided by councils, landcare groups.”

However both 1080 and brodifacoum have similar properties in that they can poison and kill any other creature that ingests the poison. In other words it just doesn’t kill the target species such as rats or possums, but will kill non-target species such as birds and animals like deer. that may ingest the toxic bait.

Secondary Poisoning

Brodifacoum and 1080 have another similarity, called “secondary poisoning”. In other words a dead poisoned animal remains toxic and any bird or other creature scavenging the dead body, takes in poison.

“Non-target organisms are potentially at risk in two ways: from direct consumption of baits (primary hazard) and through eating poisoned rodents (secondary hazard)” explains the International Programme on Chemical Safety.

Scientists C.T. Eason and E.B. Spurr in 1995 in a study “The Toxicity and Sub-lethal Effects of Brodifacoum” said insectivorous birds (e.g. bush robins, fantails) are likely to be exposed to brodifacoum by eating invertebrates that have fed on toxic baits; i.e., they are likely to be at risk from secondary poisoning. Predatory birds (especially the Australasian harrier, New Zealand falcon, and morepork) might also be at risk from secondary poisoning by eating birds, small mammals, or invertebrates that have fed on toxic baits.


Scientists  in a study “The Toxicity and Sub-lethal Effects of Brodifacoum” said insectivorous birds (e.g. bush robins, fantails)

 — are likely to be at risk from secondary poisoning.

Predators are greatly at risk. Both poisons are very slow to kill, and especially so with brodifacoum. An animal be mouse, bird or insect, on taking the poison, slowly dies and in its distressed, weakening state, quickly attracts the attention of predators among them native birds such as bush falcons, hawks, moreporks, pukekos and wekas.

Ecological history is littered with instances following poisoning.  For example  Eason and Spurr said the “entire weka population on Tawhitinui Island, Pelorus Sound, Marlborough Sounds was exterminated mainly by direct consumption of rat bait (Talon) intended for ship rat control.”

The scientists cited instances of harrier hawks, found dead after eating rabbits poisoned with brodifacoum, moreporks found dead from secondary poisoning after eating rodents poisoned with Talon rat bait and southern black-backed gull —- at risk from secondary poisoning by scavenging on poisoned carcasses.

A dose of poison below fatal amounts is described as sub-lethal. Scientists Eason and Spurr referred to “sub-lethal doses of brodifacoum which caused abortions and reduced lambing rates in sheep.” 

Endocrine Disruptor?

Have 1080 and brodifacoum that “endocrine disruptor” which basically is the undermining of fertility and conception rates in a species? Is breeding and reproduction inhibited resulting in longer term population decline?

It is questionable because there appears lack of research and little if any information, into whether both poisons have the “endocrine disruptor” characteristic.

Nevertheless  Eason and Spurr refer to sub-lethal doses and reduced reproductivity in sheep.

The two scientists said “indigenous New Zealand vertebrates most at risk from feeding directly on cereal-based baits containing brodifacoum are those species that are naturally inquisitive and have an omnivorous diet (birds such as weka, kaka, kea, and robins). The greatest risk of secondary poisoning is to predatory and scavenging birds (especially the Australasian harrier, New Zealand falcon, southern black-backed gull, morepork, and weka)”

The duo added “the risk from brodifacoum will be at its greatest when saturation baiting techniques, such as aerial sowing, are used in eradication programmes.”

DoC is “aerially sowing” Ulva Island with brodifacoum.

Seven years later in 2002, Spurr and Eason along with two other scientists produced a study “Assessment of risks of brodifacoum to non-target birds and mammals in New Zealand”.

The quartet of scientists described brodifacoum as “highly toxic to birds and mammals”.

“Vertebrate pest control programmes in New Zealand using bait containing brodifacoum have resulted in the primary and secondary poisoning and sub-lethal contamination of non-target species. These include native raptors, such as the Australasian harrier (Circus approximans) and morepork (Ninox novaeseelandiae), other native birds such as the pukeko (Porphyrio melanomas), weka (Gallirallus australis), southern black-backed gull (Larus dominicanus), and kiwi (Apteryx spp.), and introduced mammals, including game animals.”

Dead Dotterels

Other studies have identified the lethal nature of brodifacoum.

Landcare Research scientist Penny Fisher said “because brodifacoum persists in the environment, other birds may suffer secondary poisoning from eating animals that have ingested poison” and cited “a high mortality of New Zealand dotterels following an aerial brodifacoum operation at Tawharanui Regional Park North Auckland, in 2004. At least 50% of the dotterels in the area at time of operation disappeared or were found dead. Sand-hoppers-common food item of NZ dotterels —ate baits and accumulated brodifacoum and provided a potential route for transmission of the toxin to dotterels.”

In 2004, MPI noted detection of brodifacoum residues in liver samples of wild pigs particularly in areas such as the Marlborough Sounds where absent bach owners had scattered brodifacoum rat poison around their properties. Wild pigs either ate baits directly or ate toxic rat carcasses.

Residues were still detected in some wildlife at least 24 months after brodifacoum use ceased.

Two dead eels found in a Southland waterway had brodifacoum in the gut contents of one and that “suggests the eel had recently ingested food containing brodifacoum, probably through scavenging the carcass of a poisoned possum.”

High Residues

Brodifacoum similar to 1080, leaves residues.

In 2005 a paper in the New Zealand Journal of Marine and Freshwater Research, Volume 39, told of freshwater crayfish (koura) with significant 1080 concentrations and 1080 residues in eel tissue that were on average 12 times higher than the PMAV (provisional maximum acceptable level).

The INTERNATIONAL PROGRAMME ON CHEMICAL SAFETY Health and Safety Guide No. 93 said of brodifacoum “as a technical material — is highly toxic for fish”.

Processing poisons for wild animal control/eradication is Orillion a State Owned Enterprise governed through a Board of Directors appointed by the New Zealand Government. Orillion’s safety data sheet for brodifacoum says “may cause long lasting harmful effects to aquatic life.”

Therein lies a threat to not only valued sports fishes such as trout and juvenile salmon migrating downstream to sea, but also native fish such as eels and galaxids.

Sodium fluoroacetate, also known as compound 1080, is the poison around which controversy swirls. Brodifacoum is little known but is surreptitiously used by the Department of Conservation and councils.

1080 is ecologically destructive and damaging to the ecosystem – but brodifacoum is far worse.

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14 Responses to Brodifacoum – a Lethal Poison Like 1080 – but Much Worse?

  1. Jack Tuhawaiki says:

    Well said.
    The UK’s “The Guardian” in April 2022 ran an article which said “A highly toxic rat poison is killing increasing numbers of birds of prey, figures show, as wildlife campaigners call for its use to be banned outdoors–There has been a sharp rise in the number of birds of prey in England found with the rat poison brodifacoum.”
    The Department of Conservation is sadly so out of touch.

  2. Golde says:

    The New Zealand government if full of very stupid …very sick b*s**rds. They have destroyed a once beautiful and Once special place. I am so sorry for all the good people there.

  3. Bud jones JonesQSM says:

    It is not widely appreciated how this entire chain of poison is kept in motion, but as in many things to find the evil, follow the money back to the source. Here we have a complete package of a nose in the progressive trough from funded “research” to establish a necessity, Manufacturing, transport, & dispensing; more “research” to complete the fraudulent need with a pat on the back for the job well done, leads to a beaten path to the next “job”The public is suitably conned & the money machine spits out for another round .The TV news will cover it with a moedicarrot kea for the loading of the poison bait into the hoppers, chopper ready to fly. Media takes another dolop of funding from the Public Interest Journalism Fund, having satisfied the moedi content clause with the carrot kea & good bye “Key Whore ya”.Livelihoods thrive, cultural guilt niceties are warm & fuzzy, careers are safe science has rubber stamped the expenditure. Everyone is happy apart from 1000’s of animals in horrific pain for lengthy periods before death. But ain’t we done good, saving the earth from those nasty pests?? !!!

  4. Lew says:

    The poison lovers are going from half mad to totally mad.
    Brodifacoum was used to poison rabbits on MacQuarrie Island it resulted in thousands of seabirds being poisoned.
    If the dopey sods can’t get rid of a few rats on a tiny Island such as Ulva they should all be sacked.

  5. Dr. Charlie Baycroft says:

    We need to stop believing that what is right or wrong matters to people with political influence and authority.

    They only care about what they want or don’t want and they have the auhtority and use of public funds to force the rest of the people to agree with them.

    If people want to stop the use of these cruel and dangerous poisons they need to stop complaining and get politically active so that they can put ntheir representatives into parliament to do what they want.

    There are not as many politically influential people as we tend to think.
    Politial parties ddo nto have many members.
    Few of the members are active, influential or even aware of who is making the decisions and choosing the political celebrities.
    It would not be very difficult to inflitrate, disrupt and change the policies of the political parties if people really wnated to.

    The silent majority of people might disagree with this poisoining of their environment but they will nto be asked and have no effective representatives in the government to speak for them because THEY CAN’T BE BOTHERED.

  6. Ferg O'Grady says:

    Dr Baycroft is so correct. People can’t be bothered. They are indifferent. Apathy is rife. So stop complaining amongst yourselves and get politically active as Dr Baycroft suggests. Join a political party and propose remits to national conferences. That is where policies – good for bad – are born.
    The article is a “wake up” call. Brodifacoum is widely used by regional councils but gets very little mention in the media, who anyhow by government’s handouts with conditions attached to “toe the line” are failing in their duty to readers. It is corrupt.
    Brodifacoum is a terrible poison. So is 1080.
    The Zero Invasive Predator 2050 type of ideological campaigns are madness. After all, who will be around in 2050 to hold the poisoners accountable?

  7. The Ulva Island poisoning is demonstrably illegal. Under the Conservation Act, DoC is required to preserve natural resources, defined as plants and animals of all kinds, systems of interacting living organisms, and their environment. Also, under the National Parks Act, areas of New Zealand that contain ecological systems that are unique, or scientifically important, must be preserved as far as possible in their natural state.

    Aerially spread brodifacoum causes large losses of animals; Ulva Island has many unique species; ecological effects are unknown; and there are viable alternatives for rat control.

    Known losses
    DoC’s bird monitoring has recorded deaths of 20% of kaka, 86% of fernbirds, 65% of robins, over 90% of pukeko and 98 % of weka following aerial brodifacoum (DoC, 2011). Internationally, the Macquarie Island aerial brodifacoum operation killed over 2400 birds (Parks & Wildlife, 2014) and at Rat Island, Alaska, an “unexpexctedly high” number of deaths across 26 species occurred following aerial broadcast of brodifacoum baits (Ebbert & Burek-Huntington, 2010).

    Species that are long-lived with low reproductive rates have a particularly low ability to recover from large population decreases caused by aerial poisoning (Spurr, 1979).

    The high kill rates of birds represent a massive loss of genetic diversity which is vitally important to species’ resilience, i.e. the ability to adapt to major environmental challenges, such as weather events, new diseases and competitors (Innes et al., 2010).

    Effects on other animals
    Molluscs (Conus) and insects (Drosophila) are poisoned by brodifacoum (Walker et al., 2001). Negative effects on terrestrial invertebrates were found on Kapiti Island (Sinclair et al., 2005) and Perlorus Bridge (Spurr, 1996). Aerial brodifaoum on Fregate Island, Seychelles, impacted terrestrial snail species, one of which become endangered and the other probably extinct (Gerlach, 2005).

    NZ geckos are known to eat brodifacoum baits, and the baits killed Telfair’s skinks on Round Island, Mauritius (Hore & Hare, 2006). Sub-lethal effects of brodifacoum on reptiles may also occur (Hore & Hare, 2006). DoC has claimed that rat eradication from Ulva Island will have a positive effect on lizards by removing predators. However no study has even examined what reptiles are present on the island.

    Brodifacoum binds strongly to soil and persists for many months (Weldon et al., 2008). Soil is an important part of the ecosystem and its inhabitants are diverse and essential to the recycling of nutrients. However they get no recognition in poisoning plans. Many native species of New Zealand soil fauna are still undescribed, and the intricate relationships among individual species remain ‘terra incognita’” (

    Broadifacoum is rated as highly toxic to aquatic organisms on the basis of its toxicity to the freshwater crustacean Daphnia magna (USEPA, 1998) and has been described as a molluscicide (Gerlach, 2005). DoC’s Brent Beaven dismissed possible effects on the freshwater animals in Ulva Island’s streams (which are not excluded from poisoning) with the incredible claim that they have limited fauna, based on his having put fish traps out in two streams which “only caught freshwater crayfish”. This manager’s seemingly complete ignorance of the diverse, vulnerable species in freshwater environments is revealing of the depth of ignorance within DoC. Freshwater animals are specifically mentioned in the Conservation Act. DoC has a stated duty to be concerned with all shellfish of the Classes Mollusca and Crustacea that inhabit freshwater.

    The marine environment will be contaminated. Toxic dust from aerial baiting spread at least 1 km (Wright et al., 2002). Ulva Island receives high rainfall and frequent gale force winds so significant movement of soil and sediment from land into streams and the sea is likely. The coastline is jagged and rock stacks make up a total of 5 hectares. Even with the greatest care, baits will land in the sea. In a North American aerial brodifacoum operation that DoC advised on, a deflector bucket was used for upper areas of cliffs and the lower areas and coastline were sown by hand, yet there were many baits in the sea (Howald et al., 2010). Toxicity of brodifacoum to NZ’s marine invertebrates has not been investigated, although it was noted that paua were initially absent and slowly repopulated the area over the year following the spill at Kaikoura (Primus et al., 2005).

    Unique species on Ulva Island
    A tiny study of ground litter and tree trunks on Ulva Island found 62 different species, that were distinct from those on the mainland (Michel et al., 2008).

    There needs to be an independent scientific appraisal of the project, from a reviewer without any vested interests or biases (such as financial reward, career advancement or zealous nativism).

    Alternative control methods should be considered seriously. The small size of the island, easy topography, ecology of Norway rats and a 100 x 100m grid of bait stations that was used on the island in the initial eradication of rats all make ground control potentially very effective.

    There is considerable knowledge of the best ways to trap Norway rats, and other means of control include using detector dogs to find burrows, fumigating burrows with cyanide, releasing radiocollared “judas” rats to find others, and using a confined (Delilah) rat to attract others. There is a need for field-trialling these other techniques to refine them (Russell et al., 2008).

    The Ulva Island situation presents the opportunity to reset the course of ecological management from blind, irreversible poisoning with unpredictable outcomes, to careful, adaptable treatment, with concurrent monitoring of effects.

    (Full references available on request)

  8. Sally Forth says:

    Animals who have been introduced to New Zealand are often described and wrongly called pests. They are villified and demonised. Why? Simply because bureaucratic empires and jobs are created. So to keep the salaries and bureaucracies going, the propaganda is created with spin doctors proliferating.
    NZ just a tiny country, comparitively speaking, has the dubious distinction of using 90% of the world’s usage of 1080. Now brodifacoum is added to the arsenal of poisons.
    Thank you for the exposure.

  9. J B Smith says:

    I was shocked to read of the cruelty. Three weeks, i.e. 21 days, it takes brodifacoum to kill an animal!

  10. About the mid 1980s when I was employed by the then Marlborough Pest Destruction Board as Area Foreman , just before I left starting up my own Pest Control Firm . ( as the powers that be, with Govt cut backs , started hunting Rabbiters & NOT Rabbits! ). //// The story was that Brodifacoum was replacing 1080 ? as 1080 was causing so many Livestock & Dogs deaths ! //// Now our REAL problem in New Zealand, no matter what type of Poison methods we use for Pest Destruction/ Control we (they) , are far too HEAVY HANDED with the HUGE amounts chucked in our Environment ! Please see my last Letter to CORONZ ?( cop the bit about M.Ps Legislating ) //// So we have 1080 & Brodifacoum Etc. ,”really overused” in the Mountains & Bush ! then down on the flat & lower hills the sad overuse/ application of all the Ag /Hort Chem & Fert ? and we all wonder why our water qual is out the window . // How is 1080 & Brodifacoum overused ? when a block of Bush is bombed by air > Chopper / Fixed wing , Toxic Pellets must end up in Native Birds Nests, as they are facing “UPWARDS” in the Canopy ? acting as a serving tray for our Birds to eat! left high & dry & NOT breaking down as quickly as on the Forest Floor . ///// Also bad news, it also ends up the soaks & streams ? I have never known a Possum Or Rabbit actually living under water !! /// So how do we solve this ? just slow down the “Gung Ho Overuse” & stop using a Bull Dozer to crack a Walnut . /// As far as our Native Birds go ? they are a KEY with Climate Change as they both pollinate & spread Forest Seed ? how did that big Rata get to grow down that steep gully ? Sure as hell no Human ever planted it . //// You may ask how we used 1080 back in the day ? We put it down under runners,( Tomo’s ) out of the way, at arms length ! Never bowled any stock & had good Rabbit Kills, the Cockey’s were over the moon , that they didn’t have to shift any Livestock & of course they had to keep a close eye on their dogs & pick up any Dead Rabbit parts later ,along with us , the Hawks had so kindly flown downhill with & dumped ! even quarter of a K away . //// Thanks .

  11. golde wallingford says:

    I said this before….and I will say it again……apathy is the enemy of freedom.

  12. Brerpossum says:

    Was recently at Ulva Island and very surprised to see the signs there warning of Poison being laid, I have to wonder what the tourists think when they see these signs and there were quite a few the day we went. Kiss goodbye to a whole lot of those birds of which were quite a few.
    DOC must be thick to think that removing the deer off the island is going to help stop removal of baits, the deer would probably just eat it and then die. great sight for tourists to see dead or dying deer.
    Like Jack says Doc is so out of touch its not funny!

  13. Kwassie says:

    Lucid enough for me, but clear as mud to the powers that be.
    Total travesty.

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