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Predator free NZ – necessary, a fantasy or brilliant?

Deer exclusion plot showing the impacts of wallabies and deer (note the difference in vegetation inside and outside the fence).

I am lucky enough to spend a large amount of time in some of New Zealand’s most beautiful places and every week see a menagerie of NZ’s endangered species. Over the last 25 years I have worked in the great outdoors both here in NZ and overseas. I have tried hard to create meaningful nature based experiences for more than 50,000 people (including over 40,000 students over the last decade specifically in formal conservation education programs). I have been privileged enough to work at the “pest free” fenced sanctuaries Zealandia and Sanctuary Mountain Maungatautari as education manager roles. With this experience in addition to visiting numerous pest free offshore island sanctuaries I have seen first hand the benefits of a “pest free” environment.

During this time I have watched a seachange in attitudes to conservation in New Zealand. This is vastly different to the negative attitudes towards “greenies” and “treehuggers” I experienced in my formative years as a child of “native forest action council activist” parents during the torrid time as people fought for the protection of NZ’s native forests.

With this background, you may think I would support the idea of a “Predator Free NZ”. Yet I remain unconvinced. Here’s why.

There is a huge difference in pest control and pest eradication! “Predator free” implies none not few.

New Zealand does pest control reduces the number of pests to hopefully a level where it gives a native wildlife a better chance to breed and survive. It is done via a range of methods including poisoning, shooting and trapping. . There are numerous groups around New Zealand operating pest control programs at varying scales with mixed results. Many of these rely on dedicated volunteers with very limited funding.

Pest eradication is getting rid of each and everyone and most importantly keeping it that way. New Zealand has world-leading expertise in eradicating pests. Largely this has been done on islands both large and small and more recently New Zealand’s fenced sanctuaries.

The easy access to Tiritiri Matangi in the Hauraki Gulf, or Kapiti Island North of Wellington and now even more so fenced sanctuary’s like Zealandia, Sanctuary Mountain, Okoronui, Tawharanui and more bely how difficult it is to keep them pest free.

Fenced sanctuaries such as Zealandia and Maungatautari are only as good as the maintenance of the fence and full time monitoring to respond to any incursion. Zealandia and Maungatauitari have had incursions as a result of damage to the fences and both have manged to successfully eradicate the intruders. In Okoronui a stoat incursion wiped out the south island saddleback translocation before the stoats were caught. It requires a herculean effort to maintain the fences and monitor for incursion, the staff in these organisations need to be applauded.

Island’s have the natural barrier of water around them, yet a couple of years ago a stoat incursion on Kapiti Island cost over $300k to resolve. As I write this I am watching a stoat on a wee island in a wetland outside my window (hopefully he investigates the trap I put out for him).

Stoat on a wee island out my window!

Stoat on a wee island out my window!

In contrast, pest control efforts reduce the number of pests to improve the breeding success of the native species within the area. This works well in spite of great pest control infrastructure Mount Bruce in the Wairarapa has suffered twice at the hands of a ferret on a rampage killing significant numbers of kiwi before being caught.

Note the difference in terms “pest free” and “predator free”. Offshore Islands and fenced Sanctuaries that are pest free have no introduced mammals at all (although fenced sanctuaries haven’t cracked the mouse problem yet and some have kept sheep and cows for farming reasons). No cats, rats, stoats, ferrets, weasels, pigs, goats, deer, cows, sheep, hedgehogs, possums, rabbits, hares, dogs or even mice

Getting rid of the full suite of introduced mammals is important to restore forest health. Predator free NZ now says stoats, ferrets, weasels, possums and rats are their target. No mention of eradication of dogs (significant killer of kiwi) or cats (political suicide?). Also, the relationship between these predators is interesting as DOC’s “battle for the birds” shows. E.g beech mast year = rat boom, rat boom = stoat boom, rats run out of food and rat population crashes, stoats shift to birds for prey.

Browsing animals do significant harm to forests but the hunting lobby is strong and again talk of eradicating ungulates is politically impossible or possibly unnecessary.

Deer exclusion plot showing the impacts of wallabies and deer (note the difference in vegetation inside and outside the fence).

Deer exclusion plot showing the impacts of wallabies and deer (note the difference in vegetation inside and outside the fence).

Sir Paul Callaghan is quoted as saying a “pest free nz” is NZ’s “moonshot”. The”moonshot” idea is simply a great metaphor for continuing/increasing research into new pest control and eradication techniques. Waiting for scientists to come up with the holy grail “breakthrough” may or may not happen. Scientists have been researching in this area for generations. Incidentally, there is already funding and research activity into pest control research already. Biodiversity protection is listed as one of NZ’s science challenges. And don’t forget our existing techniques are based on generations of good science!

Using the best guess model Auckland University has costed a “predator free” New Zealand at $9b. That’s roughly the size of our dairy or tourism industries or $2000 for every man, woman and child in New Zealand! The level of monitoring and response required to keep NZ pest-free even if eradication was attempted would be extremely expensive and would need to be done forever. Where is the initial and ongoing funding coming from?

Sir Paul also supported something far more practical, achievable and affordable for immediate conservation gains. In his final public lecture, he spoke passionately of:

– Creating a dozen “1000 hectare fenced sanctuaries” in the heart of the conservation estate (think Pureora, Whirinaki, National Park, Fiordland, Te Urewera, the Caitlins). These areas should align with DOC’s national ecosystem management system. Invest where the habitat is the best!

– Each fenced area would be surrounded by 10,000 hectares of intensively managed “halo” pest control

– each “halo” would be surrounded by 100,000 hectares of cyclical hunting and aerial pest control

Rough costings were done at $84m spread over 25 years. Or $7m per year. This is a far more realistic, cost-effective and achievable goal. This idea uses existing proven technologies, will protect wildlife and habitat now! It will protect habitat where it needs protecting, i.e in our ancient forests! This would represent approximately 15% of the conservation estate and 20% of DOC’s existing budget. This big idea is one which the NEXT foundation should support, it is realistic, something that all New Zealanders can get behind and would certainly be a game changer for conservation.

Daniel servicing a fabulous "goodnature" self setting trap

Daniel servicing a fabulous “goodnature” self setting trap

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