Carolyn King looks boldly at a future where kiwi and other native birds might roam safe from introduced pests.
Kiwi are our national icon, yet New Zealand’s five species of kiwi are all seriously at risk. Two are perilously close to extinction, and one has been extinct on the mainland for decades but survives on offshore islands and in Wellington’s Zealandia sanctuary.
To lose any one of our kiwi species would be a national catastrophe. Extraordinary danger calls for an extraordinary response, and over about the last 20 years there has been a massive increase in effort and funding dedicated to reducing the threat to kiwi.
Three successive Kiwi Recovery Plans, published by the Department of Conservation, have documented the research, the public involvement and the management plans that have been developed to save the kiwi. Today, says the current Recovery Plan, about 70 community groups actively protect kiwi over a combined area of 50,000 hectares, in addition to the 70,000 hectares managed by DOC.
Yet, it continues, “the fight for kiwi is far from won”. Part of the problem is a matter of geography. A model developed by Britta Basse and John McLennan estimated that the minimum reserve area needed for long-term continuation of a self-sustaining population of northern brown kiwi is at least 10,000 hectares.
Kiwi chicks born on smaller areas protected by rigorous predator control are likely to survive their first few months but, if not fenced
in, they are also liable to disperse into unprotected areas outside. Only large single areas of 10,000 hectares-plus give them enough room to disperse and still remain protected from their main enemies, stoats and ferrets (for chicks) anddogs (for adults).
Arthur C Clarke’s guide to Carolyn King looks boldly at a future where kiwi and other native birds might roam safe from introduced pests.
The problem is that predator control over such a large area is, with present technology, very difficult and expensive. Worse, when successful, it can precipitate consequences: removing stoats alone from their normal average density of three per square kilometre permits numbers of ship rats to increase to higher than their normal average of almost 400/km2 – and even at their average density, ship rats have a proportionately greater chance of encountering a bird’s nest than do stoats.
But removing rats unleashes plagues of mice, and mice at plague numbers can destroy large numbers of the ground invertebrates needed by kiwi; hedgehogs do the same even at normal density. Clearly, effective management must not just control, but actually remove the whole interconnected suite of small mammal predators.
In the present state of our technology, to do this long term over even one area of 10,000 hectares could be done only by magic, which in the materialistic world we live in, means it cannot be done.
Should we despair? No, for three reasons suggested by Arthur C Clarke, the author best known for dozens of science fiction novels, including 2001: A Space Odyssey. If that sounds like a fantastic suggestion, you need to know that Clarke was not only a gifted writer but also a rigorously realistic and perceptive, future-oriented scientist. In his SF writing, Clarke postulated advanced technologies without resorting to flawed engineering concepts or explanations grounded in incorrect science or engineering.
He avoided taking cues from current trends in research and engineering, which eventually make many other writers in the SF genre sound outdated. Rather, Clarke presented ultra-advanced technologies limited only by fundamental science.
Clarke formulated three Laws of Prediction, which are:
1 When a distinguished but elderly scientist states that
something is possible, he is almost certainly right.
When he states that something is impossible, he is very
2 The only way of discovering the limits of the possible is
to venture a little way past them into the impossible.
3 Any sufficiently advanced technology is indistinguishable
The effect of Clarke’s first law is amply demonstrated by the history of rodent eradications in New Zealand. A symposium held in Wellington in 1976, attended by most working scientists of the time interested in rodent biology and protection of wildlife (not all of them elderly!), made an exhaustive review of what was then known about the effects of introduced predators in nature reserves, especially, but not only, rats on offshore islands.
The original publication is not widely available, but William Stolzenburg gives an account of the meeting in his new book, Rat Island, and adds a perceptive review of subsequent events.
Ian Atkinson and Brian Bell kicked off the first day by presenting devastating first-hand evidence confirming that the arrival of rats on an island heralds certain doom for naïve endemic birds. The logical prediction, that more extinctions must follow if island birds cannot be protected from rats, was challenged by two of the most senior scientists present, Kazimierz Wodzicki (founder of DSIR Ecology Division) and Sir Robert Falla (founding president
of the Ornithological Society of New Zealand).
Supporting data from Tony Whitaker and Graham Ramsay on the effects of rats on formerly abundant populations of tuatara and wëtä prompted more sceptical responses.
The second day discussed available methods for managing rats, and ended with the chairman making what Stolzenburg calls “an infamous statement of surrender”, that “… the possibility for complete extermination of New Zealand rodent populations by conventional control methods, even on islands, must be considered remote.Nothing that has been said this afternoon …would make me think differently”. This conclusion was pretty much
unanimous at the time, and endorsed by reputable
scientists for years afterwards.
But history has shown that Clarke hit the nail on the head: when established scientists
declare that something is impossible, there is a strong chance that they are wrong.
The effects of Clarke’s second law began to appear within only a few years. In the mid-1980s, a small band of visionary conservationists began, against all advice from more cautious heads, to challenge the conclusion of the 1976 meeting.
People like Rowley Taylor and Bruce Thomas were dismayed by the pessimistic outcome of the 1976 meeting, until they heard news of the radical improvements to conventional control technologies then emerging in overseas labs, especially the development of secondgeneration toxins such as brodifacoum. They saw the chance to develop the potential of these new toxins, allied with ultra-precise bait distribution, to venture past the limits of the possible into what had been considered impossible.
They acknowledged that there was no evidence to justify attempting a significant island eradication that had until then been only a pipe-dream, since it had never been tried
before, but they went ahead anyway. In 1988 they cleared Breaksea Island of Norway rats in a single operation of three weeks.
The result has been the ever-expanding list of successful eradications on larger and larger islands. It was true that large-island eradications were impossible in 1976, but the
arrival of a new tool in the form of Talon blocks handled by visionary operators changed that conclusion.
Now, 36 years later, and faced with the contemporary equivalent of the same question, we should learn from the wry experience of those at the 1976 meeting (some still active in conservation research, including myself): it may be true that effective multi-species predator control over the very large areas needed by kiwi cannot be done at present, but we should
be cautious about concluding that it is impossible.
The effects of Clarke’s third law will be seen in the future rather than in 1976 or in 1988. For any ordinary person without special training, advanced technology indistinguishable from magic already surrounds us in the modern world. I don’t know how smart phones work– do
you? – but luckily the world is not limited by what I can understand.
The problem is that most such wonderful gadgets were developed after huge investment by deeppocketed corporates like Apple solely for commercial profit, or as by-products of some massively funded national programme such as the space race of the 1960s. Some
of them are incidentally applicable to, or modifiable for, conservation purposes.
Mass-produced, lightweight trail cameras have recently begun to offer a critically important conservation benefit as an economic way to monitor trap evasion by rats, or the productivityand fate of birds’ nests, but their development was driven by demand from hunters.
We need other forms of advanced technologies developed to meet our specific conservation aim, to protect kiwi by reliably removing pests long term in huge areas of rugged back country. If he were still here, Clarke would be telling us that, if such magical technology is theoretically attainable, all we need to attain it is the political/social will, and lots of money.
The general view among current conservation biologists and managers is that because effective, largescale predator control is very, very expensive, it must be extremely well justified. That means, we should not commit funds to any management programme unless
there is evidence that it will produce the intended benefit.
Benefit is, of course, not counted in piles of dead pests, hugely satisfying though that may be, but in benefit to the protected resource – usually measured as whether enough pests have been removed to prevent damage to nesting birds. Damage prevention is essential to protect the remnants of threatened mainland species, especially to kiwi chicks, but in an ideal world it would be a short-term solution only. What we really want is long-term security for our unique native biodiversity.
Suppose Clarke is right for a third time and within, say, another 36 years we had developed that longed-for magical technology, unimaginable now in the same way that clearing Breaksea Island of Norway rats – and even more amazing, Campbell Island – was unimaginable to those at the 1976 meeting.
Suppose further that this magical technology was economically practicable and without unacceptable side effects, making it feasible to envisage large-scale eradication of small mammal pests on critical chunks of the mainland.
That would be the point at which, inspired by Taylor and Thomas and their heirs, we would need to seize the opportunity to go beyond the existing evidence and to discover the limits of the possible by venturing a little way past it into the impossible. Then the aim of establishing
multiple 10,000-hectare kiwi sanctuaries free of pests might become reality.
Maybe even bigger things could follow.