The hidden risk for the world’s smartest bird

Department of Conservation —  30/06/2021

It’s Mount Cook in winter and a kea is standing on the hut roof. It’s working out just the right time to flick snow onto the heads of the poor people walking below.

Kea playing with road cones. 📷: Andrew Walmsley © │

This sums up the kea, the bird that New Zealanders made a roadside gymnasium for, in an attempt to distract the cheeky birds from shifting road cones into the middle of the Homer Tunnel. 

Kea love tinkering. They often turn on taps, and a kea once managed to lock a mountaineer in the toilet at the Mueller hut.

Conservation devices used in kea habitat have to be ‘kea proof’. We have to use extra-long screws to secure the stoat traps, so that kea can’t prise them open and end up tangled in the devices. 

But unfortunately, sometimes the kea’s curiosity and intelligence work against the bird.

This iconic Nationally Endangered species is endemic to the South Island and taonga to Ngāi Tahu. Yet they’re in serious trouble across half of the species range and we don’t have the benefit of time to save them.

Kea displaying flagrant disregard for the rules at Pass Hut. 📷: DOC

There are now huge gaps where kea used to be present. It’s estimated there are only about 3000-7000 kea left, and in areas without predator control they are still declining. 

For some context, there are 68,000 kiwi left. 

So what’s the problem? Well, kea are ground-dwelling birds, making them incredibly vulnerable to predators. The ‘public enemy number one’ for kea is considered to be stoats; that clever, voracious hunter that can live in any habitat, swim, climb, and hunt at day or night.

But new research shows a new enemy has emerged. 

A kea was once spotted having a tug-of-war with a feral cat over a rabbit carcass. In that particular moment, the kea was holding its own. Sadly, it appears since then the feral cats are winning out.

Feral cats are killing kea, in numbers comparable to stoats in eastern parts of the South Island. 

Since 2019, a five-year study has followed the progress of 45 radio-tagged kea in areas east of the Southern Alps/Kā Tiritiri o te Moana between Lewis and Arthur’s passes, mostly in valleys where there is no predator control.

Researchers want to learn what is driving the decline of the birds east of the main divide. Thanks to this study, we are learning more about the dangers of feral cats.

So far, 13 of those 45 kea have been killed by predators. The cause of death has been about evenly split between feral cats and stoats.

A circus of kea (yes, that is really the collective noun). 📷: Shellie Evans © │

To figure out the cause of death, the field team sends the kea corpse away for forensic analysis. They also use field signs to determine the likely predator, using techniques you’d typically see on police shows on TV. This may seem like overkill to some, but kea really matter.

Let me explain. When a cat kills a larger bird like a kea, it’s a mess. There will be feathers everywhere. The corpse might be discarded in a prominent place above ground. Cats have stronger jaws than stoats and will easily chew through a kea’s leg bones, so the metal leg bands that a kea wears slide off and are often left lying beside the corpse.

A stoat’s kill is quite different. They often decapitate their prey, and then eat the muscle and tissue. Then, like a squirrel, they store what’s left in different caches underground for later.

Keas are sturdy but they’re not fighters. They don’t use their beak – they freeze and rely on camouflage. That said, they’re physically more of a challenge than, say, a rock wren.

The thing is, if feral cats are killing kea, imagine how hard it is for our other smaller species. 

Feral cat eating a parakeet on Auckland Island 📷: Finlay Cox

We already know that kiwi, whio, weka and rock wren are either sparse or gone from many South Island eastern habitats, and that’s largely due to introduced predators.

The problem with feral cats

Of course, it’s not news that feral cats kill native species. Kākāpō had to be removed from Rakiura/Stewart Island after feral cats brought their numbers down to 60. A single feral cat in Ohakune killed 102 short-tailed bats in seven days. Threatened reptile populations like Grand and Otago skinks are critically low due to depredation by feral cats, and research is currently looking into the damage they inflict on the whio/blue duck population.

We know it’s really hard to place blame on specific predators for the decline of a species. 

But, as a country we appear to have a blind spot when it comes to feral cats. These incredible hunters live right across New Zealand, from sea level to 3000 metres up. They are extraordinary predators that have huge home ranges. One feral tomcat on the Auckland Islands was recently tracked hunting over a 60 square kilometre area – that’s four times the size of Auckland Airport.

Feral cat eating a white-capped mollymawk on Auckland Island 📷: Stephen Bradley

Even if they’re well-fed, a cat’s prey drive means they love to hunt and they’re built for it. They can see in a sixth of the light needed by humans, and hear the ultrasonic calls of rodents.

If you’re picturing feral cats living their best lives out in the wild, I’m afraid that’s not the case. Feral cats have tough, short lives. They’re often starving and diseased. The females are pregnant repeatedly from a young age and sometimes unable to look after their litters.

So what’s being done about feral cats?

We’ve known that feral cats are a problem for many native species for a while now, and the Department of Conservation (DOC) has a mandate and best practice to manage them on public conservation land where it can.

That doesn’t make it an easy job, though. Feral cat control is expensive, labour-intensive, and much more difficult in areas where kea are present because they can get caught in the traps too.

Another problem is that we don’t really know how many feral cats there are in New Zealand. We do know their preferred food source is rabbits when they are present, so where you find rabbits, you are more likely to find higher numbers of feral cats. It looks like this is why we have a problem east of the main divide – where farmlands and drylands (typical rabbit habitat) border kea habitat.

While we haven’t solved the feral cat problem yet, there are some good precedents to take heart from. It took until the mid-1990s to find out that stoats were killing kiwi chicks at a rate that was rapidly leading to the decline of the species. Today, we’re very good at stoat control. Once we understand a predator, we can deal with it.

Thanks to this study, we’re getting new data demonstrating the extent of the feral cat problem for kea in the east.

We’re also developing new tools for more efficient control of stoats and feral cats. DOC is leading the development of baits for use with the toxin PAPP (para-aminopropiophenone). In Australia they use a similar carnivore bait for cats and foxes. This work is still in the early stages though, and we still need to be confident that it’s safe for native birds.

To help us manage kea as well as possible, we need to understand everything we can about the species’ behaviour, preferred habitats, and population dynamics both now and in the past. We’re currently working with iwi to figure out where the gaps in our knowledge are, and we’re drawing from mātauranga Māori as well as western science for this.

“Do not feed the kea”. 📷: Andrew Walmsley © │

What can we do?

If you see a banded kea, let us know. The kea sighting database set up by the Kea Conservation Trust has been hugely successful for keeping tabs on birds. Over 10,000 sightings have been recorded by the public, meaning we’ve got great data on kea movement. This can inform how we manage them. Recently, a hunter in Whataroa on the West Coast sent in a photo of one of the 45 study kea from the Eastern South Island project. Romano the study kea had just decided to fly 96 kilometres from home.

Love this bird, but from a distance and please don’t feed them. Our obsession to get a wildlife selfie for the gram isn’t as harmless as it may seem in the moment. Experiences with weird urban food make kea more likely to try other strange things – plastic, lead-head nails, or 1080 pellets to devastating effect.

Oh, and do what you can to control your own domestic cat. There is absolutely a place for domestic cats in New Zealand, but our feral cat problem is fuelled when people don’t look after their pet properly. 

If you don’t get it desexed and microchipped, you can end up with unwanted kittens. Some unscrupulous owners dump these kittens in the wild, and if they survive, they may eventually become feral and top up the population.  

A cat that was found with 17 native skinks in its stomach was black and white – that’s not a colour combination that lasts well in the wild on the New Zealand mainland. The ranger who found it thought it was likely to have been a recent descendent of a wandering domestic cat from nearby.

The good news is that kea can be very productive in the absence of predators. They breed most years, and successful breeders fledge between one and four chicks each season. That’s the kind of population growth we need for this long-lived and slowly reproducing bird. If we can get predator numbers low enough so that they can breed successfully, this species can bounce back. We have a long way to go and need everyone to pull together to give the smartest bird in the world a fighting chance. 

38 responses to The hidden risk for the world’s smartest bird

    Dave Punter 17/07/2021 at 1:07 pm

    Releasing a neutered feral cat back into the wild ist he most rediculars idea I’ve ever heard of it is well known that a neutered cat will live 2 or 3 times longer than an un neutered cat and we need the cats gone now.
    1080 will never control feral cats we need the government to put people on the ground and trained search dogs to locate these pests.

      Laurella Desborough 17/07/2021 at 1:56 pm

      Dave Punter you are RIGHT about this feral cat nonsense. Too many people are willing to sacrifice wild native species to these wretched feral cats. They need to be removed asap. Your idea of trained search dogs is great…getting the cats out and about where they can be exterminated would work. Bury the bodies to prevent lead poisoning of other creatures who might eat them.


    If wild cats are involved, I think it is just natural. It is part of the food chain. But having domestic cats turned to feral ones and started to hunt these birds, then that is different already.


    If we are talking about feral cats, then I think it is just natural. It is part of the food chain. And I’m sure these birds will be able to adopt to that environment.

      Laurella Desborough 11/07/2021 at 12:45 am

      Sam, Feral cats are an INVASIVE SPECIES. They are NOT NATIVE. That means those feral cats are NOT part of the natural food chain. Therefore, they need to be REMOVED. Responsible cat owners need to be keeping their cats INDOORS or in outside CATIOS. Otherwise, each cat owner with a free roaming cat is assisting in EXTINCTION of native species.


      Yea give them 100s of yeas if not 1000s to evolve…. Oh that’s right they will be extinct by then either by predation, habbiat interference or secondary poisoning so won’t get the chance to evolve.

    Laurella Desborough 07/07/2021 at 2:50 pm

    There needs to be a law passed that require cats to be INDOORS or in OUTDOOR CONTAINERS and no where else. Along with that, there need to be teams of hunters going out and shooting feral cats or any cats found in the forests and lands where wildlife live. Cats are a serious predator and will kill just for fun…so, ELIMNATE THE CATS. This should be a very easy solution…and no TNR either…that is a feel good NON solution.


      Good luck with that. Govt is too conserned about keeping the public happy and majority love fluffy wuffy.


    Cats are one of the most efficient hunters and are widespread. I’ve caught feral cats in the alpine valleys around Arthurs’s Pass, the McKenzie Country and right down to sea level on the Westcoast. They are incredibly aggressive when trapped and will go for you. The ordinary household cat is a killer, at one time we had a cat that brought mutilated skinks home on a regular basis. It’s time for pet cats to be subject to the same rules has dogs.


    By having trappers on the ground they catch cats. By dropping 1080 and having no trapping cats run riot, you are taking away the natural food source for the cat, mice and rats and they pray on birds.. The aftermath of 1080 also creates a rat plague so the whole problem starts all over again..
    The Forest Service tested dozens of traps, the best trap over all by a long way was the Lanes Ace the Australian Rabbit trap commonly known as the gin trap. The trap that preformed the worst was the victors trap the trap that doc prefers the most..
    Doc have set up trapping to fail by banning the gin trap, so they can use 1080.
    Bring back trapping and Ban 1080..

      Chris Windley 04/07/2021 at 3:04 pm

      Spot on. And in recent times, DOC have done trials with Goodnature traps in Fiordland, and got stoats down to zero, over a year. The results of these trials have been kept secret, so the poiosn campaign can go on. But, if poison is not used on the rats and mice, birds are left alone. Birds are only 6% of a stoats diet prior to a 1080 drop. After the drop this climbs to 56% And still they poison!


        Goodnature traps have variable success rates. And the NZ bush is far too big to put any traps at the spacings required, and we don’t have enough people in the country to tend them. Don’t be silly Chris.


        Ask sue if she has seen the feasibility study for ground trapping that was given to bill English, nick Smith, sir Paul Callahan and Maggie barry whick all were in support with. At times it’s pointless talking with people who put there hands over there ears and say no no no I’m not listeing to you. But I will politely say that’s OK. The information is there.


      Cats are killed in 1080 operations in same way as stoats are killed very effectively, by secondary poisoning from eating the dead rats. There are plenty of trap designs available, but it is just not practical to trap all of the conservation areas, even if trappers were available.


        Again 2012 feasibility study was presented to deputy prime Bill English, nick Smith, Maggie barry and even Sir Paul Callahan had commended the non toxin feasible study. The alternative method was aval and put on the table. It got swept under that carpet.


      After a 1080 drop there are poisoned rats and possums lying around. Feral cats eat them and die. Exactly the same way stoats and ferrets die from 1080.


        Same method with endangered. Pretty valuable poision baits if yr relying on killing 2 birds with one stone via secondary poisoning. The fact is msds states safety measure which is ignored and excuses are made. They are just excuses. There are massive employment opportunities in nz. Environmental experts and conservationlists are itching to have the opertunity to do the world’s biggest pest eradication project ever attempted. Your saying that what would now be billions of dollars over the last 60 yrs is the only way when we could have been spent on targeting the introduced target species and doing the job right rather then making up excuses for why it is the only way. Why pour more fuel on the fire? Its not going to put it out.


      Doc also tested good nature traps which and reports show that they are highly successful , goodnature are still used successfully down south In high value conservation estate. No kea deaths confirmed in good nature a24s, just speculation. And 11 confirmed kea kills in the doc 150-200s. Doc managers work agaist seasoned experience ground trappers who have way more effective results.


    Blaming cats is yet another distraction to hide the fact you have been proven to be systematically poisoning Kea to death all over the country with 1080. You’re liars and hypocrites and contributing to the ecocide of so many species, including us.


      What rubbish. When ZIP arrived in the Perth River area, they took a census of local kea: around 60. After the first breeding season following the 1080 drops, there were 168 kea. That’s the kind of increase that will save the kea, and it is thanks to 1080 destroying the predators.


        Any form of pest control is better then none. However if you stand in a forest and experience the full spectrum of this poision method you may get an idea of what it involves. If pfnz2050 aims for eradication and John Innes (doc) has done thorough studies to conclude rodent populations explode after arial drops then yes. You are right Sue. Some bird species will bounce back for a few years. So how long has it been. Over 60 years with the use of deadly poision. And have you bothered to cauculate the overall species decline for all species effected by sodium fluoroacetate? It’s a quick fix that will not do what it is intended to do. Eradication. Get that in your head.

    Neville Du Fall 02/07/2021 at 6:09 am

    DSIR did a 25 year longitudinal study of the Orongorongo river valley. A 25 year in depth study of all that lived in that valley and what impact each had on the ecology. It is one of the most comprehensive investigations ever undertaken in New Zealand. This was not done by workers it was done by scientists.
    One of them, Robert Brockie wrote the book A Living New Zealand Forest which condenses the research results into a book.
    Cats. I quote, “Birds provided 4.5% of the cats diet by weight in the Orongorongo Valley. Further on, Of the birds killed, most were non native, and it then identifies the species of bird remains found.
    The book has a chapter dedicated to their research on cats.
    DOC, you need to read this book, then read the original research. How can you get it so wrong or alternatively what has changed so much in our environment that has driven cats to prey switch to the extent you are suggesting???
    Cats prey/food of choice is rabbits, rats and mice. It is a no brainer, a food source abundant in most locations, easy to catch and the cats manage to avoid a mouth full of feathers.
    DOC’s own propaganda tells us the country is overwhelmed by rats.
    I suggest that the recent “research” is actually propaganda driven by the long term agenda, being to total eradication of any and all mammals from the NZ bush.


      Stoats don’t live exclusively on birds as prey. But they are very dangerous predators of birds like kea, attacking them in their nests and killing even adults on the ground. DOC are well aware of all the research, much more up to date than your old reference and covering many other areas.


        Then why do doc use doc 150-200s?if they are well aware that 11 kea have been killed in these traps alone?


      Neville, DOC have identified what killed each kea. They do gene analysis on saliva from the body, etc. They know what cats are doiing to kea. I* know you anti-1080 people are specialists in denial – fortunately no-one takes you seriously.


        That is a hypocritical comment that a anti non toxin person would make. I think nev has a posative attatude and your insinuation is defamatory. Some pro poision are specialists in defamitory towards anyone who presents factual information. There is no relavant outcome by being antagonistic with such attatudes. Please reframe from these methods of negative rhetoric. We need to communicate in a respectful manner.


    Cats needs to be licensed, microchipped and limited the same as dogs. People have cats indiscriminately and appears to think they are harmless even when they tell you about the present in the form of a bird that was deposited at their feet.

    Alan Rennie 01/07/2021 at 5:36 pm

    DOC you are a bunch of wankers,,FACTS..
    26% of kea in a population could be killed in a 1080 operation,
    DoC’s Dr. Josh Kemp said “The Franz Josef Kea deaths had “shocked and stunned” DOC” (Stuff 28/01/09)
    But Kea deaths from 1080 poison have been proven for over 52 years.
    In 1964 Protection Forest workers picked up 4 dead Kea and 8 dead seagulls after a single 1080 drop. The birds tested positive for 1080 poisoning. (M.H.Douglas: Control of Tahr: Evaluation of a Poisoning Technique July 1966).
    To find 12 large poisoned birds on foot would indicate the death rate must have been devastating for all the bird species in the area. DoC like to blame the decline in Kea numbers on early bounties “ Kea had numbered in the hundreds of thousands but were devastated when a bounty was paid to kill them because of concerns they attacked stock.” (Press 29/07/08)
    In 2011, DoC poisoned 7 out of 11 Kea at North Okarito ( 60% mortality). DoC’s excuse this time “It seemed likely the more open nature of the North Okarito forest was a factor, Mr Costello said” (ODT 12/09/11)
    DoC then went on in 2013 to kill 5 radio-tagged Kea at Arthur’s Pass, DoC’s excuse this time “the repellent was less than the target concentration”( Stuff 21/08/13)
    If such inane, puerile excuses were put forward by CYPS or the Police next time a vulnerable child is brutally killed, the media and politicians alike would take the offending officials to task. DoC appear immune from such scrutiny.
    In 1999 DoC’s Dr’s Elliot and Kemp said “Kea nests appear to be relatively immune to predation from introduced mammals…Our results agree with a previous study of Kea nesting at Arthur’s Pass, where no evidence of significant nest predation was found (Jackson 1963).” (G Elliot & J Kemp 1999)
    Now DoC claim “The Kea deaths are unfortunate but without protection most Kea chicks are killed by stoats. (Westport News 26/01/15)


      Scientific studies have linked the
      effects of the aerial application of 1080 to an increase in kea nest survival.
      Researchers examined the effects of aerial 1080 on the reproductive success of West
      Coast kea and found that kea nest survival increased from 46.4% prior to the
      application of 1080, to 84.8% after the application on 1080. Kea nest survival in areas
      that were not treated with 1080 declined from 21% to 12.2% within that same period
      of time.


      You may not agree with docs decisions. I appreciate Yr honesty but abusive behaviour is uncalled for and does not do any good for anyone apart from self satisfaction for the like minded. Doc have accomplished many good things over the years. I do not see communities getting organised enough to make a non govt environmental group. Although it is prevalent that the only way has an impact on species unable to recover. Poision is not all that they do. And remember it is the govt that gives doc funding so they have to manage that. However as most who have investigated it is doc management that is the issue. Many doc staff may get a fat pay check but do not like the acts they have to do and have no say on the matter. Its the managers who decide this. Just like it is the govt that makes the funding for doc. You keep talking like this you will continue to be marginalised from having a say. Sure share the relavant info but please bite Yr tounge with name calling. Many doc staff do not get paid to be abused and deserve the same sort of respect as you or I. Do not threat. All UN investigated incadents are documented. These crimes against the envirment will be put on trial. Let hope its not too late when they do.


    Last year I did the North West circuit in Stewart Island. There were cat footprints throughout the sand dunes. But no oystercatchers on the whole trip and only a couple of skinks – cats are bringing lizards and shore birds to extinction. In addition, white-tailed deer have totally altered the forest under-storey and it’s a well-known fact that deer hunters avoid shooting hinds to ensure deer stocks are boosted.

    I had gone to Stewart Island assuming that I would see a thriving natural ecosystem. Sadly that’s not the case – cats and hunters rule the roost in what should an internationally significant gem.

      Neville Du Fall 02/07/2021 at 6:19 am

      There were Moa originally on Stewart Island, the South Island Giant Moa, so Stewart Island had always been grazed. The deer have replaced the Moa as a means of spreading seed and maintaining the biodiversity of the island as it was.

    Russell Pullar 30/06/2021 at 1:00 pm

    We putting some firewood in the woodshed at the Mathias Hut when we saw a young cat, it flew passed us and into the forest, this was the weekend before the big flood.


    I know cats can swim, but to Auckland Islands?

    Society needs to be more responsible in disposing of cats. While I have ever seen ferals in the bush. I certainly had them in a rural environmental area and did destroy any I saw. with an air rifle

    Carole Frances Long 30/06/2021 at 10:36 am

    It is also very unfortunate that there are groups set up to capture feral cats, neuter them and then let them go again in the wild – do they realise that those cats will kill native birds for about 10 years if they live that long? Surely it would be more realistic and cheaper to despatch these predators with an injection.

      Laurella Desborough 23/07/2021 at 3:16 am

      Those TNR cat people live in a fantasy world of “wonderful sweet cats” which is far from the truth. The public needs to push the government to pass laws to CONTROL cats, either by keeping indoors or in outside containment. Otherwise, they need to be ELIMINATED from the environment. Cats have caused many extinctions and that needs to STOP.