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Rewilding
Oisín Sweeney
What is rewilding and how does it apply to Australia?
Aldabra Tortoises created grazing lawns at the Francois Leguat Giant Tortoise and Cave Reserve, Rodrigues, Mauritius by Arnaud Meunier
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Nature is under more pressure than any time since humans have been the dominant species on earth. The rate of species loss has led some to suggest we have moved into a new geological period, the Anthropocene. Climate change is accelerating and governments seem powerless to act decisively to head off the worst impacts. So against this dark background, what can possibly be done to protect nature and help make sure as many species as possible can adapt to the future? One potential solution could be rewilding: a novel approach to ecology that focusses more on re-establishing ecological processes and species interactions rather than considering species in isolation. Proponents say it could be a way to ensure that in an uncertain future ecosystems can respond to change.
The rise of rewildingRewilding is an ecological approach that is becoming more and more prominent in Australia and overseas. It was first described in Wild Earth magazine in 1998 by the distinguished ecologist Michael Soulé. This version very much focussed around restoring populations of keystone species (those with a disproportionately
large influence on other species and ecosystems), particularly large predators, in well connected intact landscapes1. The most cited rewilding example involves wolf reintroduction to Yellowstone National Park in the USA. Following the wolf reintroduction, elk numbers were reduced via predation and their grazing behaviour was changed through fear of the wolves. But the ecological response went beyond elk to include a recovery of aspen2. This phenomenon, where plants are indirectly influenced by animals, is known as a trophic cascade. In turn, an influence on trophic cascades is one of the important features that identifies a keystone species, in this example the wolf. Since 1998 rewilding has gained in popularity, with many conservation organisations advocating rewilding. Crucially, rewilding has also been really successful in capturing the public imagination. That’s because it takes an optimistic approach to conservation rather than a traditional, well, conservative approach!
Rewilding is not just carnivoresLarge carnivores are still a key part of many rewilding approaches, but they are not the only element in rewilding. Many other approaches are taken in rewilding efforts around the world. See Nature NSW for a broad overview. For example, ecological surrogates are species, sometimes non-native, that are introduced to perform the
DingoWitte-art.com
“... what can possibly be done to protect nature and help make sure as many species as possible can adapt to the future?
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same ecological role as an extinct species. Giant tortoises have been used on Mauritian islands as ecological surrogates to restore the dispersal of ebony seeds. In Europe, North America and Russia the restoration of large herbivore populations is a key element of rewilding because of their influence on vegetation, such as opening forest canopy and cycling nutrients.
What about Australia?In September 2016 NPA, supported by Conservation Volunteers Australia and Taronga Conservation Society hosted the first National Rewilding Forum in Sydney. The aim was to investigate rewilding in an Australian context and to ask questions such as what is and is not rewilding? What are the main goals of rewilding, and how do we achieve them? We felt this was necessary because some cautionary voices point out we don’t have stated aims of rewilding or a consensus on what defines rewilding3. Frans Schepers, managing director of Rewilding Europe, gave a keynote address and outlined some of the notable successes and approaches taken across Europe.
A full report of the forum outputs is available here. The following is a brief summary of some of the key issues.
Ecosystem functionThe restoration of ecological processes (like flooding, soil turnover by animals and seed dispersal to name a few examples) and interactions between species (like predation and scavenging) was repeatedly identified as a key rewilding goal. This focus on processes is important in returning control to nature, reducing the need for human management and ensuring ecosystems are resilient to change. It would also mean a shift in the management emphasis from aiming for an ideal condition of nature from a human perspective, as we currently do, to making sure ecological processes can take place and promoting interactions between species. The advantage of this approach is that in a time of rapid change it is impossible for humans to manage the multitude of species individually. Ensuring ecological processes
are occurring means that although the balance of species may shift over time, ecosystems can respond to change and continue to function.
FencesFences are really interesting in the context of rewilding. They are used to exclude introduced mesopredators (foxes and cats) which are key threats to mammals weighing between 35 grams and 5.5 kilograms that are vulnerable to extinction. These species are termed Critical Weight Range (CWR) mammals. Fenced enclosures work, with much larger and denser populations of CWR mammals than the broader landscape. However, they are very expensive to erect and maintain - the NSW government is spending $41 million over five years on fenced enclosures - and they can’t be applied over a large area. So are they “wild”? The forum identified fences as necessary step in rewilding as we look for solutions in the broader landscape, but they’re not a rewilding end point in themselves.
PredatorsKeystone predators were identified as being a key element to making sure ecosystems were able to function properly. Native predators such as dingoes and Tasmanian devils are thought to be able to exert control over foxes and cats and enable coexistence of native CWR mammals and these introduced mesopredators. This control can occur both by predation and by changing behaviour, like the wolves in Yellowstone. Of course, this raises a tricky issue: because of fears about killing livestock, dingoes are persecuted in Australia, including in protected areas. These fears may be unfounded4. The hybridisation of dingoes with domestic dogs doesn’t help. The hybrids are known as wild dogs and are deemed worthless because they are not pure dingo, regardless of their ecological function or the degree of hybridisation. Evan Quartermain of Humane Society International wrote an article in the Nature NSW explaining why this differentiation may be misguided.
“What are the main goals of rewilding, and how do we achieve them?
“... in a time of rapid change it is impossible for humans to manage the multitude of species individually
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Oisín is the Senior Ecologist with the National Parks Association of NSW, an environmental NGO dedicated to protecting nature through establishing and linking protected areas. His interest in rewilding stems from its potential to shift the focus of conservation from one of negativity (look what we’re losing) to hope (look what we can achieve). Other interests include forests and spiny crayfish. He lives in the Shoalhaven, spends lots of time in the fantastic national parks there and can be occasionally found face down in the waters of Jervis Bay looking at fish.
Community and peopleOver the course of the forum, participants repeatedly stressed the importance of making sure communities were involved in rewilding for our efforts to have the best chance of success. The importance of humans is immediately apparent in the context of predators. Although predators are seen to be very important in rewilding, many farmers are opposed to predators because they’re perceived as a threat. Hence, finding novel solutions as a community is vital if we’re to restore the role of predators. For example, Rewilding Europe has built community benefits into rewilding programs by funding and promoting nature-based businesses.
Where to next with rewilding in Australia?There are lots of projects going on already that fit the definition of rewilding, but they’re not happening under a shared vision or with a clear set of goals or principles. That shared vision is one thing we want to work towards so that groups involved in rewilding are moving in the same direction. There's obviously much work to do in many areas, like predators. But equally, there are other areas where rewilding principles could be applied relatively easily, such as restoring hollow formation and letting forests grow old via ending native forest logging and restoring flood regimes to degraded wetlands to
recover vegetation and animal populations. Any action that increases the number of interactions and restores ecological processes contributes to the goals of rewilding. That’s the beauty of the concept.
References1 - Soulé, M. & Noss, R. Rewilding and biodiversity: complementary goals for continental conservation. Wild Earth 8, 19-28 (1998).
2 - Ripple, W. J. & Beschta, R. L. Restoring Yellowstone’s aspen with wolves. Biological Conservation 138, 514-519, doi:http://dx.doi.org/10.1016/j.biocon.2007.05.006 (2007).
3 - Nogués-Bravo, D., Simberloff, D., Rahbek, C. & Sanders, N. J. Rewilding is the new Pandora's box in conservation. Current Biology 26, R87-R91, doi:10.1016/j.cub.2015.12.044 (2016).
4 - Allen, L. R. Wild dog control impacts on calf wastage in extensive beef cattle enterprises. Animal Production Science 54, 214-220, doi:http://dx.doi.org/10.1071/AN12356 (2014).
Eastern quoll Marc Faucher
“... the importance of making sure communities were involved in rewilding ...
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