Comment

Gareth Morgan: NZ’s inconvenient truth

Gareth Morgan rejects arguments made by conservationist Wayne Linklater this week, instead making a case for toxins remaining an essential tool to protect our wildlife

I found it difficult to disagree with the primary thesis of Wayne Linklater’s views in the media this week. Empirical evidence can support a hypotheses or theory but the theory remains credible only until such time that new evidence is uncovered that conflicts with the hypothesis – and that may be never. Such is the nature of science, the credibility of a theory relies heavily on the supporting evidence and can be destroyed the instant contradictory evidence is validated.

Further, Wayne’s point that the same evidence can convince one observer but not another, is not uncommon in science – or law for that matter. The weight of evidence is often as tall a hurdle to a theory’s credibility as the strength of evidence. For example, one person may accept the risks around the results of a certain dosage while another may not. In the extreme, some may only accept there being absolutely no risk of failure before accepting the dosage is a valid treatment, worthy of applying.

All this means is that one has to be quite specific about the risk of success or failure with a certain treatment, and secondly the definition of “success” has to be precise.

In the instance of evidence that toxin-based tools have been successful in arresting the local extinction or decline in numbers of target native species, there are plenty of before and after scenarios that evidence success - as measured by the proponent, and there are cases of utter failure and thirdly there are cases of ambiguous outcomes. Such a record is not unique to toxins, the deployment of traps have produced variable results as well.

However, one undeniable fact is that some of these native taonga – both fauna and flora –  are becoming less numerous and others appear to now be extinct. The battle to save what remains and indeed boost their population is one that nowadays attracts much support – as attested by the commitment of successive central and regional governments and the rapidly expanding network of private and community predator control and eradication projects. There is then an increasingly strong effort to prioritise the survival and resilience of local populations of native species – to the point where the aspirational goal of “Predator Free 2050” has become the catchcry.

This, as Wayne Linklater points out, is the measure of success proponents of maintaining or increasing biodiversity employ – that a major decrease in numbers of the exotic predators that have been introduced to New Zealand since European settlement needs to be achieved if our native species are going to survive, let alone thrive. He is absolutely correct to assert that such a hypothesis is not in itself proof that such an outcome for our taonga would come about automatically if PF2050 is achieved. Other threats such as climate change will no doubt have a role to play. The condition of reduced predation is necessary but not sufficient.

But – and this is a very important proviso – we can be reasonably sure that higher populations of these predators will accelerate the extinction of our most precious native species. There are plenty of before and after stories to tell what happens to local populations of native species once predator eradication, or even control, is achieved.

A toxin-laden demise will often be cruel but such inhumanity is hardly unique to toxins alone – death by fly-spray is hardly less humane than being torn asunder by a cat.

Which makes it interesting is why anybody would oppose the presence of toxins in the toolkit for predator eradication. The most credible reasons seem obvious – their ‘misuse’ resulting in damage to non-targeted and valued species; and secondly the cruelty the method inflicts. The second is easiest to dismiss – a local population of native species overwhelmed by the numbers of imported predators is likely to suffer no less cruel a demise than death by toxin. I remember domestic cats we owned killing prey not because they were hungry but just for the fun of it, the pure entertainment derived from a bird flapping its way to a grizzly death thanks to the hijinks our cute little kitten would deploy. A toxin-laden demise will often be cruel but such inhumanity is hardly unique to toxins alone – death by fly-spray is hardly less humane than being torn asunder by a cat.

Prevention of cruelty to animals is a noble cause of course, but it does raise the issue of where to draw the line. The proliferation of malaria, zika, and dengue via mosquitoes have all been commonly dealt to by spray of toxin. Which is the greater evil – the death of predator or prey? This is a dilemma animal rights advocates continually face and are stunningly crude and arbitrary in the selectivity of their judgment calls.

The second objection to toxins I suggest is more substantive – that the by-kill or risks to human health are too great to warrant their deployment. Ultimately this becomes an empirical matter upon which a value judgment, as Mr Linklater would label it, then is required. An evidence-informed perspective would identify and quantify those risks and the value judgment would declare whether they warrant protection of our fauna and flora taonga – or not. Ultimately that is what the public needs to decide. There’s an abundance of before and after studies that support the toxins case and as well there’s evidence where toxins have been mis-used or best practice not followed where unexpected collateral damage ensues. The correct response surely is to continually improve the deployment of best practice.

Then there is the argument that other methods – such as trapping – can just as economically deal with predator invasion. That argument is simply wrong, the cost advantage of eradication by best practice deployment of toxins as opposed to traps is overwhelming in all but small-scale exercises of predator control. So in the context of a predator-free New Zealand, toxins are an essential part of the kit. I’m unaware of any cost/benefit work that has demonstrated on a large-scale site that trapping is cost competitive. We could of course argue that the cost doesn’t matter that either we should pay whatever is needed or not bother protecting the taonga. Such a blanket opposition to toxin on these grounds, is of course a value judgment – of the inescapable kind Mr Linklater identifies. By the way, I continue to invite researchers to prove non-toxin methods that are competitive at scale; nothing would delight me more, I’d be your greatest fan.

There are several projects underway searching for cost-effective alternatives to toxins on large landscapes, but so far the best results emanate from approaches that include toxins within the arsenal. Solutions that enable a vastly reduced but more precise deployment of toxins have to date delivered the most success. But the technology has yet to deliver any viable toxin-free solution.

Given the efficacy of toxins as one of the tools, anti-toxin proponents then are  left having to argue that protection of our natural taonga on the scale envisaged is not worth it. In other words, in the New Zealand context given the current technologies, they have little choice but to acknowledge that their position is inescapably an anti-wildlife one; theirs is not a conservationist perspective. Given the current state of technology we cannot prevent extinctions without deployment of toxins – at least not without unbounded cost. For some that might not matter, but I suspect for many that inconvenient truth ensnares them in a state of denial – they’re left rejecting evidence because it contradicts their prior view: ‘no toxins under any circumstances’. This, I would suggest to Wayne Linklater, is a strikingly more paradoxical position for a conservationist to find oneself in, than being bold enough to make the value judgment that ‘wildlife matters’.

I find that it’s their rationale that plonks the anti-toxin proponents in the unenviable position that climate change-deniers or anti-vaccination lobbyists have landed. Better by far, surely, not to surrender our native fauna and flora (throwing this baby out with the bathwater), but instead support efforts that continue to refine and lessen our dependence on toxins to save our wildlife. That’s what some of us are prepared to spend our own time and money investing in saving and enhancing. I welcome all conservationists to join those efforts – and suggest that informed New Zealanders already hold that position.

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