Controlling stoats, rats, and possums is a cornerstone of NZ conservation, but are we overlooking deer, goats, and more?
In a new paper, NZ researchers say deer and other hoofed browsers have been mostly ignored, and this is just one problem in how we manage national biodiversity. They think our current conservation approach is unbalanced – and part of larger, systemic failures.
The SMC asked experts to comment on the research.
Dr John Leathwick, retired researcher, Christchurch, comments:
Note: Dr Leathwick is a coauthor of this paper.
“This overview of current conservation management in Aotearoa New Zealand gradually evolved in shape as we explored complex changes in attitudes and ideas over the last century. We started out aiming to address our concerns over the degree to which the impacts of increasing numbers of deer and other browsers were seemingly being ignored in so much of New Zealand’s biodiversity management. However, as we dug deeper into the reasons underlying this neglect, we became increasingly aware that the free rein given to deer was but one expression of a wider set of issues with Aotearoa New Zealand’s current approach to biodiversity conservation.
“These include the challenges of coordinating management effort among growing numbers of groups and individuals involved in conservation; the sometimes undue influence exerted by particular interest groups; the growing dislocation between key aspects of conservation policy and management and a large body of Aotearoa New Zealand and international science; and our failure to adequately measure what biodiversity gains our pest management activities are actually delivering.
“The aim was not to undermine the value of predator control, which does deliver measurable gains for some species – it’s more that we want to encourage a much more holistic, systems-approach to biodiversity management, while also promoting much stronger linkages between biodiversity management and its underpinning science. Only by broadening our management beyond its current focus on just one threat to our native species and ecosystems do we have any hope of achieving the goals set out in our recently revised national biodiversity strategy.”
No conflicts of interest.
Emeritus Professor Dave Kelly, Biological Sciences, University of Canterbury, comments:
“This is a very important paper, which I think is a comprehensive and accurate summary of the problems facing conservation in Aotearoa. The paper is consistent with recent work presented by other ecologists at the latest conference of the NZ Ecological Society in December 2022.
“I have taught students that the goal of pest control is always to protect threatened native species, not to kill pests. Predator Free 2050 has certainly gained public attention and support, but the resulting efforts sometimes involve pest control that has little chance of reducing the pest density, or little chance of benefitting threatened species. Leathwick and Byrom are right that good science should underpin all conservation work.
“I think this paper shows that the Department of Conservation is charged with protecting our endemic biodiversity, but it has been progressively hobbled, by inadequate funding and by inappropriate input from vested interests. It was always obvious that Predator Free 2050 only listed pests with “no friends”, ignoring important ones (pigs, deer, feral cats) that were politically more delicate. Hunters should have a right to manage animals on private land (whenever that does not harm neighbours), but there can only be negative biodiversity outcomes when hunters influence management of pests on public conservation land, including National Parks.
“Crucially, extinction is irreversible. If any endemic species go extinct, it’s a loss of taonga, a moral and political failure, and a violation of international treaties that Aotearoa has signed up to. We need to stop pretending that conservation can happen on an arbitrarily small budget, and only in places and on species that don’t upset anyone else. It is already well documented that the current approach is not halting declines in Aotearoa’s biodiversity. Leathwick and Byrom’s recommended actions could halt the decline.”
Expertise note: I worked at UC from 1985 until retiring in November 2021, but continue with research. I have done research on bird declines and pest control in NZ, including on the impact of mast seeding on pest outbreaks in South Island beech forests. I also lectured on pest control at UC for more than 30 years.
No conflicts of interest. “I was not involved in the work. I have no financial interest in, or current research grants on, pest control.”
Professor James Russell, Professor of Conservation Biology, University of Auckland, comments:
“John Leathwick and Andrea Byrom provide a thorough review of a century of mammalian pest control in New Zealand and make a sound case for expanding mammalian herbivore management in New Zealand, which as the authors state needn’t come at the cost of predator management. Indeed, the authors’ own figure shows that recent predator management efforts have added funding into the system, while not meaningfully detracting funding from other pest management initiatives. This recent upsurge in funding, and public support, for predator management, reflects the increase in awareness over the past decade of the role of (small cryptic nocturnal) predators in national biodiversity decline. The emerging focus on predator management in New Zealand is neither a panacea nor a distraction, but a sound investment in bird conservation and restoration.
“The evidence for the beneficial outcomes of predator eradication is vividly demonstrated on the hundreds of predator-free offshore islands around the country. However, predation-focused management is not an alternative to, but only one part of, the New Zealand biodiversity strategy that addresses a full range of biodiversity threats, including other mammalian pests. That predators are now more commonly targeted over herbivores likely reflects societal values, and in particular that the management of herbivores is more contested socially as game (hunted) animals, than predators which tend to be universally (at least nationally) detested.
“At one point the authors argue for greater collaborative and local decision making in conservation, but elsewhere lament socio-political influences. Evidently, a middle-ground must be found in whose voices are consulted, amplified and heard within biodiversity management and governance. The authors also highlight long-standing shortcomings in the governance of biodiversity in New Zealand, and in particular the urgent need to reform wildlife law.
“Ultimately, more systematic planning of conservation incorporating ecological science could only benefit biodiversity and societal aspirations in New Zealand. At our highest conservation priority sites, such as offshore islands and mainland sanctuaries, I expect mammalian predators and herbivores, alongside exotic invertebrates and plants, will all be simultaneously managed, because as the authors state, this will provide the strongest outcomes for biodiversity.”
Conflict of Interest statement: “I receive funding from Predator Free 2050 Ltd, Department of Conservation and Auckland Council.”