Wellington Scoop

Possums aren’t bird predators, claims recreation group

Press Release – Council of Outdoor Recreation Associations
Claims by the Department of Conservation and some green groups that possums are eating birds eggs are incorrect and contrary to research says Andi Cockroft, chairman of Council of Outdoor Recreation Associations of NZ (CORANZ), a national forum for outdoor recreation groups.

“The Department of Conservation is either ignorant and incompetent or deliberately lying to keep their anti-predator, pro-1080 poison policy going,” he said.

In a series of field trials near Wellington, over several nights Andi Cockroft laid out bread and hen eggs. The idea of the tests began when he noticed that bread left the previous evening for birds had vanished at first light next morning.

“I suspected possums but it might have been rats, or other birds,” he said. “I decided to put hens eggs out too, to test DoC spin that labelled the possum as a bird nest predator. However infra-red photography over several nights showed it was nocturnal possums delighting in eating the bread but totally ignoring the eggs.”

He decided to try to induce the possums to break the eggs by coating them with golden syrup as an attractant. While the possums licked the syrup off the eggs, they showed no inclination to break even one egg.

Andi Cockroft described the exercise as “a simple high-school type experiment conducted to determine if the possum naturally consumes eggs.”

Although a hen’s egg may seem rather large by comparison to some of New Zealand’s at-risk native species, it is actually very small compared to the kiwi’s egg which was one of the largest eggs in proportion to its size of any bird in the world, even though the kiwi is about the size of a domestic chicken,

“In fact the kiwi egg is about six times the size of a chicken’s egg,” he said.

“In the area the tests were carried out, the possum population is not controlled other than by road-kill, natural attrition and me getting annoyed and culling a few of the local intrusive ones. They are generally well fed with plenty of edible plant species around that they seem to thrive upon. Naturally inquisitive and generally unafraid of either myself or my dog, they are at times a nuisance.”

Andi Cockroft said he was not surprised at the result of the trial in the light of past research. A Landcare Research study in 2007 analysed 26 possum stomach contents and showed no meat or feathers. Another study in South Westland of 135 possums showed no trace of birds or eggs. Despite these studies, the Department of Conservation regularly claimed possums prey on birds, fledglings and eggs. Even a study on possums by scientist R I Kean and wild life technician Les Pracy in the Orongorongo Ranges near Wellington in the 1950s, based on analysing 20,000 possums clearly ruled out possums eating birds or eggs. Yet the department, Forest and Bird Society and on one occasion a Landcare Research scientists had labelled possums as predators he said.

Andi Cockroft said he was not a hunter but simply a “rational conservationist.”

The Department of Conservation on the internet had used a photo of a possum and an egg to support its “demonisation” of the possum. However the photo had been analysed independently, strongly suggesting it was faked.

“The photo apparently was not even DoC’s but borrowed from some zealous extreme conservation group,” said Andi Cockroft. “This is just not good enough.”

DoC and Forest and Bird seemed to rely on that supposed video from 1993 of a possum with a rat eating a chick.

“DoC apparently have never tested on the video’s authenticity, nor it seems attempted to replicate the experiment itself, despite so many autopsies that have shown no evidence of eggs or feathers in possum stomachs,” said Andi Cockroft.

It needed independent credible science, not fabricated “research” or “paid commissioned science. Why would DoC with all it’s taxpayer funded resources not bother to check the video and photo’s veracity and instead relied solely on a third party eco-group for evidence he asked.

“In any case past research as far back as the 1950s on 20,000 possums and since clearly shows DoC making a scapegoat out of possums merely to justify government’s ludicrous PredatorFree 2050 and its associated poison programme which is killing thousands of birds and the insect food source of many insectivorous birds.”

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  1. Anabel, 18. January 2020, 12:25

    I suspect we have been prey to many lies to support the dropping of large amounts of 1080 and the predator free campaign.

  2. CC, 18. January 2020, 16:07

    There are so many flaws in Andi Cockroft’s juvenile experiments that the Council of Outdoor Recreation Associations should be ashamed of their naivety or ignorance in citing it. It pays to read the scientific evidence of experts and, of course, there are numerous films of predators attacking eggs. Realists took note of the fraud committed by the anti-1080 protesters at Parliament some time back and will not be impressed with the latest offering.

  3. Andrew Nichols, 19. January 2020, 1:27

    The videos from Mapara Firest in the Waikato 30 odd yrs ago showed conclusively kokako nest predation by possums. This latest odd lobby group is just another head of that redneck hunter hydra the 1080 conspiracy theory lobby.

  4. Dan, 19. January 2020, 9:10

    We brought the possums with us when we moved here over 180 years ago. It’s not only the possums that have had a disastrous impact on the native culture.

  5. Katy, 19. January 2020, 9:53

    So possums are innocent! Well done Andi Cockcroft for the research. Meanwhile possums and other marsupials are having a really bad time in Australia with the disastrous bush fires. I’m helping in a small way by knitting some pouches for Joeys etc. It’s so much nicer to care rather than kill!

  6. Kara, 19. January 2020, 11:47

    The possums also damage flora that native birds would live on.

  7. Counter-Culture, 19. January 2020, 11:56

    There is no such thing as a native culture as cultures everywhere have been “westernized”.

  8. BHS, 19. January 2020, 13:52

    Good research. I’ve often thought that the possum is much maligned for no good reason xvept they are Australian.

  9. Guy M, 20. January 2020, 0:19

    Oh for goodness sake people! The reasons that we kill off the possums are that they eat the fresh shoots on trees, and hence stunt their growth. They eat not only native species but also the tips of radiata pine – quite tender and tasty compared to the older, more needle-filled rest of the trees. In Aus, they eat trees that have grown accustomed to that, and can cope with the tips being nibbled off, but in NZ, our trees are not evolved to cope with possum predation and the possums do serious damage to growth. That is the 100% undeniable true reason that possums are being eliminated in Aotearoa. They have no place in our eco-system.

  10. Dan Tosfery, 20. January 2020, 12:20

    Plant more gum trees I say. Live and let live. Far better than poisoning with 1080.

  11. Andrew, 20. January 2020, 13:06

    And spreading bovine tb.

  12. Mike M, 20. January 2020, 14:01

    One small experiment proves nothing, and then to generalise from it that possums aren’t a problem shows a lamentable lack of understanding of the issues.

    Andi Cockroft does say “They {possums} are generally well fed with plenty of edible plant species around that they seem to thrive upon”, and (as others have pointed out) that is precisely why they are classified as pests. At https://www.doc.govt.nz/nature/pests-and-threats/animal-pests/possums/ DoC says

    “They eat buds, flowers, fruit/berries and nectar, which means they compete with native birds and reptiles for food sources. The growth and life-cycle of a tree or plant is significantly affected when all parts of it are eaten. Possums also have ‘favourites’ such as rātā or kamahi trees, leading to an even greater impact on these species.”

    DoC goes on to say:

    “In 1993, possums were filmed eating the eggs and chicks of kōkako and this evidence changed many people’s views of their threat to wildlife. They eat invertebrates, including weta, and are significant predators of New Zealand land snails such as Powelliphanta. They often occupy holes in tree trunks for their nests which would otherwise be used by nesting birds such as kākāriki and saddlebacks.”

    And there’s more:

    “Dairy and deer farmers have the added worry of possums spreading bovine tuberculosis. The value of economic loss in primary production for damage and control of possums is in the tens of millions.

    “Evidence shows stoats and possums are eating kea. Researchers using nest-cameras have witnessed the gruesome reality inside defenceless kea nests invaded by stoats and possums in South Westland.”

    So eggs are just one small part of the issue, as any “rational conservationist” should be able to appreciate.

  13. Farmer Bill, 20. January 2020, 15:41

    Andrew – possums arrived with no TB then they caught it from cows (?) and have spent the last few decades being vilified as TB carriers but now Regional Councils don’t seem to be dropping as much poison as they did so I guess the problem isn’t as big as it was.

  14. Andrew, 20. January 2020, 17:53

    Thanks for the background Farmer Bill. I think one could extrapolate they most likely didn’t arrive in NZ with bovine TB, nor with their particular liking for rata.

  15. Guntao Stem, 20. January 2020, 19:24

    DOC’s view about possums eating eggs has been refuted by Andi’s research. Who do you trust? My views are now 50:50 so I’ll give the benefit of the doubt to Possums.

  16. CC, 20. January 2020, 22:27

    Come on GS – the very crude experiments of someone, seemingly with a vested interest and no research skills, has any credibility? Go on line and do two minutes research or ask a qualified researcher about numerous possible variables that would invalidate Andi Cockrofts assumptions!

  17. Lilly G, 21. January 2020, 7:06

    Simple repeatable experiments and observations are extremely credible .
    Evidence shows 1080 is killing Kea.

  18. Karori Pete, 21. January 2020, 8:45

    1080 is made by the Tull Chemical Company in Alabama in the USA but is banned by most of the world. It would appear the West Coast Regional Council is going to start producing 1080 at a plant in Canterbury. No doubt GWRC and DOC will be dropping more of the stuff soon.

  19. CC, 21. January 2020, 9:14

    You are pushing the barrow a bit there Lilly. Two dozen kea killed over a period of years? One possum can do potentially do that in a few weeks! Meanwhile, using 1080 to kill predators in areas where other methods are impractical has proven very effective as an endemic bird saving strategy.

  20. Mike M, 21. January 2020, 10:39

    Possums kill kea, and kokako, and invertebrates such as weta, and land snails; and indirectly they kill other native birds and reptiles by eating their food and occupying their habitats.

    One-off research that has not been peer reviewed refutes nothing at all – and anyway eggs are just a small part of the damage wrought by possums.

    This is a classic straw-man argument: focus on an insignificant issue while ignoring the key factors.

    CORANZ ought to know better: why are they supporting a species that is a major destroyer of the outdoor environment that they rely on for their recreation?

  21. Sue Boyde, 21. January 2020, 12:54

    This weird tendency of the anti-1080 people to refuse to believe facts that don’t suit them. The Australians have recognised that brushtail possums predate on several species of Australian bird. Here, the black cockatoo.

  22. Andy Mellon, 21. January 2020, 14:39

    @Lilly G. Evidence also shows that Kea nest survivability increases substantially post 1080 drop. Kea are most susceptible to predation on the nest. Adult Kea are generally only predated by the largest of predators – Ferrets and Feral Cats. However, chicks are different entirely – predated by a wider variety of mammalian predators -and survival of chicks to fledge in unprotected areas can be as low as 10%. It doesn’t matter if the adults can survive if there’s no chicks to replace them. The real fear for Kea long term survival is if feral cats penetrate the remaining heartlands on the West of the divide. Populations in Arthur’s Pass have seen breeding rates rapidly decline as adult females have been predated on the nest.

    1080 helps improve the nesting success by some quite significant proportions (~40%). A monitored site at Okarito showed 15 chicks fledging within 2 years of a 1080 drop compared to only 5 in the preceding two years. Furthermore, the risk to Kea of 1080 exposure is significantly higher where humans interaction and feeding occurs. Very few Kea deaths have been recorded at remote 1080 sites (e.g. Wangapeka valley in Kahurangi NP or Mount Arthur) most deaths have occurred where Kea interact with people, get fed and then seem to be more willing to try eating things that are not their natural diet. Most Kea deaths post-1080 have occurred at places like Otira or Okarito.

    So, yes, 1080 is killing Kea. 1080 treated areas see Kea populations grow due to improvements in nesting success subsequently. If we want to improve Kea survival, we need to stop feeding them and we need to be concerned about feral cats (a threat that 1080 doesn’t address)

    There’s plenty of scientific literature out there on this. Rather than picking the fact that 1080 kills Kea (it does), the broader understanding of the interrelated dependencies is vital if the species is to survive. If we do nothing, it will not survive. Simple as that.

  23. CC, 21. January 2020, 15:50

    Karori Pete – of course 1080 is banned by most of the world as it kills their endemic species which, unlike here, are predominantly mammalian. No need to guess why it is a successful tool for the recovery of New Zealand’s unique flora and fauna.

  24. Ray Meers, 21. January 2020, 16:44

    The brushtail possum is mainly a herbivore and eats shoots roots and leaves.

  25. Mark, 21. January 2020, 17:39

    1080 has done nothing for the recovery of flora and fauna . Which is why erroneous information supporting the continued use of this indiscriminate poison has been distributed in NZ to support its continued use when other nations have banned it.

  26. Potamous, 22. January 2020, 8:54

    Pete there is a theory circulating around NZ academic circles that 1080 is the cause of Kauri dieback. It kills the insects that aerate the soil and dig tunnels that provide channels for water. So it becomes dead soil, waterlogged full of the fungus-like pathogen Phytophthora agathidicida.

  27. Kelly M, 22. January 2020, 16:09

    Agree Mark it’s time people stopped being brain washed and ignorant about the poison 1080.