9 Dec 2020
ON A MISSION TO RESTORE AND REWILD AUSTRALIA
It’s easy to look out at the Australian bush and see a landscape that seems untouched by humankind. It’s a unique and timeless beauty. In reality, people have been connected to and changing our ecosystems for millennia.
The first cohort of humans arrived sometime around fifty thousand years ago. While their arrival certainly changed the landscape, the second wave of human appearance a little over 230 years ago has caused the most significant wave of extinction seen in Australia.
To provide some perspective on our current extinction rate, between 130,000 and 10,000 years ago Australia lost approximately 50 mostly large mammal species. On average, that’s roughly one species every 2,000 years. In the past 230 years, we’ve lost 34 mammal species.
That’s one species every seven or so years – which is almost 200% above the ‘background’ rate of extinction.
What went so wrong with our landscapes?
The first hundred years of European arrival brought land clearing and extensive destructive agricultural practices that saw the overstocking and associated vegetation losses across much of Australia’s vast rangeland ecosystems. As Aboriginal populations living on Country declined, so did their fire regimes.
Fire was vital for creating fertile hunting grounds, but it also induced ecological succession in vegetation communities. This creates a mosaic of habitats that supports a diverse range of species.
The proverbial nail in the coffin for many of our small mammal species though was the deliberate introduction of cats and foxes. By the time European explorers had tracked their way across Australia from the east to west, cats had already arrived.
Cats had probably reached most parts of Australia by the 1880s, with foxes establishing across the continent by the 1930s – a mere 60 years following their introduction. These two species caused what is singularly the greatest mammal collapse on any continent in recent history.
Why do we need to rewild Australia?
Hasn’t the continent found a new balance? The 2019 index for threatened and near-threatened mammals in Australia shows us that between 1995 and 2016 there was a 38% decrease on average in Australian mammal populations across all sites for which we have data.
This demonstration of the continued downward trajectory for at least 57 mammal species provides us with a clear mandate that the key threatening processes for Australia’s wildlife are still operating. Therefore, we need a circuit breaker to turn things around, and ‘rewilding’ might provide just this.
Rewilding Australia’s ethos has been not to accept that we should simply hold our position. Our ambition has been to move beyond the conservation of existing degraded ecosystems and to restore vital elements of ecosystems that might improve resilience to invasive species, drought, and bushfire.
Regenerating Australia with WWF-Australia
For the Rewilding Australia team, the opportunity to fully integrate our vision into WWF-Australia’s innovative wildlife and landscape regeneration program, Regenerate Australia, provides us with a once-in-a-generation opportunity to upscale our ability to reverse this trend.
Our focus has been on restoring ‘keystone species’. We can group these species into two important categories – the ecosystem regulators (the carnivorous quolls and devils) and ecosystem engineers (the little diggers, like bandicoots, bettongs and potoroos).
These species keep our forests healthy and play vital roles in seed dispersal and plant germination. Emerging evidence demonstrates that our wildlife has significant roles to play in reducing bushfire intensity by burying leaf litter, and in keeping agricultural landscapes healthier, by aerating the soil and predating on pest animal species such as insects, mice and rats.
But herein lies the problem…
How do we rewild Australia with the clear and present danger that foxes and cats pose to our wildlife?
How do we bring back the species that were once found in their hundreds of thousands, or perhaps even millions, but now lie in at the periphery of their former broad ranges?
The easiest way to bring these species back to landscapes is to exclude foxes and cats completely. Islands are great for this, or you can create an artificial island using a fence. Fences are also vital, however, expensive and require constant maintenance.
Animals within a fenced sanctuary are also potentially subject to inbreeding depression, disease outbreaks and other random events that can befall a population that is restricted to a relatively small range with no opportunities for dispersal outside that range.
The species that we are trying to protect from cats and foxes can also, perversely become more predator naïve behind a fence, meaning that these species may become less able to coexist with predators over time. We simply can’t give up on the other 99% of Australia that we can’t put a fence around.
We need to see sanctuaries and islands as stepping stones for bold ‘outside-the-safehaven’ reintroductions. Reintroducing our missing fauna to the broader landscape will take research and bold on-ground trials that help determine how we must manage the threats now found in our ecosystems.
Bringing the eastern quoll home
Since 2018, Rewilding Australia has been trialling a program to test just that. The eastern quoll is a species that has become entirely absent from its former mainland range and is now found only in Tasmania. With this loss of arguably our most beautiful species from southeast Australia’s forests, we have also lost the multitude of interactions the quoll played within other parts of their ecosystem.
Eastern quolls were here until at least the mid-1960s. The longer time goes by though, the shifting baseline of expectation means that people forget about why this species is so important to its ecosystem. The issue was summarised quite succinctly by an ecologist writing on the loss of the eastern quoll. He wrote, “The sad thing is not that we lost the eastern quoll on mainland Australia, it’s that we haven’t tried harder to bring it back”.
Together with WWF-Australia, we’ve been working on a collaboration between government, zoos and sanctuaries and the Wreck Bay Aboriginal community to test a reintroduction to Booderee National Park on the south coast of NSW.
It’s the first time that an attempt has been made to re-establish an extinct carnivore on the Australian mainland and we have already learnt so much about how we can achieve a long-term reinstatement of the population.
We also need to start thinking about longer-term solutions to foxes and feral cats. One of the strategies that are crying out to be tested is trialling a monitored reintroduction of healthy Tasmanian devils to mainland Australia, where they lived for millions of years.
Tassie devils might provide a buffer between our mammals that are vulnerable to fox and cat predation. This buffer may come via predation or competition from devils with foxes or perhaps even via the spatial avoidance of devils by foxes. The interaction between devils and foxes is yet untested; however, in my mind, this is Australia’s most crucial unanswered conservation question. The stakes have never been higher for our wildlife.