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Is PF2050 a worthy goal considering all the myriad existential threats that we face?

May 4, 2024

Some of us were fortunate enough to have recently visited the Hen and Chicken Islands where pest eradication has resulted in deafening birdsong and restored biodiversity. You will agree that these have become wonderful, inspiring, spiritual and physical healing places.  

Roger Tuck, trustee in charge of our Science & Technology program weighs the available options to achieve PF2050. 

“In 2016 then Prime Minister John Key announced that NZ would aim to be predator free by 2050. This was the late Sir Paul Callaghan’s “Moonshot for NZ”.  It is clear to those of us passionate about restoring our natural biodiversity that we won’t achieve this without a great collective effort. We do need to use the tools that Science provides and learn from  the accrued  wisdom of Matauranga Maori.  

At Bream Head/Te Whara, over the past 20 years or so, the whenua has changed from a weed and goat infested eyesore to a place with plentiful birdsong , beautiful bush and a thriving biodiversity. 

This has been achieved using two main science driven tools, traps and toxins and vast amounts of blood sweat and tears from a huge number of passionate people, mainly volunteers. All of our main predators, rats, stoats (and other mustelids such as weasels and ferrets) , cats, possums, mice and (yes) hedgehogs are sentient creatures capable of experiencing pain and distress, so the emphasis is always on humane ways of dispatch. Most traps are kill traps, so death is immediate. Some leg hold traps are used and these are attended quickly to delay suffering.  Live capture traps also require close attention to minimise animal suffering.  

Traps are becoming incrementally more sophisticated, being able to reset themselves, or using cameras and AI in order to differentiate between target and non-target  species and using automated lures. Using AI, capture traps (which don’t harm the animal) have the potential to be programmed to release chipped domestic cats but retain unchipped feral cats. 

The major problem with traps is that they  are only useful for relatively small scale use and not for large/landscape tracts of land. Studies show that one trap per 20 hectares is sufficient for Stoats and Possums but for rats we need 1 trap per hectare. So, for example if we want to trap a 50,000 hectare native forest (not especially large), we’d need 50,000 traps, 5000 km of tracks and  500 person days to check the traps! To attempt to trap NZ free of predators would be wildly expensive and impractical.  

This is why for large landscapes we need other solutions. Toxins are currently the best tool we have for large landscapes such as South Island west coast forests. The ideal toxin would be easily spread by air, would degrade quickly and safely in the environment with no residue detectable particularly in waterways, kill quickly  and be more effective against mammals than birds. 1080 Which has been widely used and studied in NZ ticks these boxes.  Most other toxins don’t kill quickly and can accumulate in the environment. Unfortunately 1080 has polarised opinion despite all the evidence supporting it as the only effective tool  we have for large scale predator control while waiting for better solutions. 

The most promising long term tool is likely to be gene-editing to control pest fertility. With current tools, we won’t achieve PF2050. Realistically we are looking at something like a 20 year horizon to deal with the scientific and social challenges of this new gene-editing technology. 

In the meantime we cannot wait and do nothing as that will certainly condemn many native species to extinction.”

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