Rewilding Australia’s Plan – Restoring Ecosystem Function on Mainland Australia
Frequently Asked Questions about Tasmanian devils on Mainland Australia
Q: When did Tasmanian devils last inhabit mainland Australia?
An exact date is not known. There are intriguing newspaper reports from the late 1890s and early 1900s that state that remnant devils survived up until these times. The sediment fixed to a devil tooth found in Western Australia in 1972 was dated to ~430years, however this has been disputed. Devils were therefore possibly on the mainland 1000 years ago, probably on the mainland 2000 years ago and certainly on the mainland in within the past 3000 years, with reliable dating of sub-fossil remains from this period.
Q: What caused the extinction of the Tasmanian devil on mainland Australia?
A: It is likely that a combination of threatening processes resulted in the Tasmanian devils decline and eventual extinction on mainland Australia. Aboriginal hunting, the introduction of the dingo and changes in climate have all been considered. Aboriginal hunting, and in some parts, the current absence of the dingo mean that two of these potential threats are no longer operating. While there may be other newer threats (like foxes), the absence of hunting and dingo pressure in some habitats mean that devils may now be able to survive within these landscapes.
Q: Why is it important that we test a mainland reintroduction of the Tasmanian devil now?
A: Tasmanian Devil Facial Tumour Disease (DFTD) is still spreading through the Tasmanian devil population within Tasmania. In some regions up to 95% of devils have been killed by it. The potential for this disease to affect the evolutionary pathway of the Tasmanian is not known, however already scientists are seeing the species living in lower densities as well as breeding earlier in their lives than would otherwise happen. By establishing a population of devils in environments without the threat of DFTD we will ensure that we conserve two metapopulations of devils that may be traveling down different evolutionary trajectories. By having a mainland population of devils we are also ensuring that we have genetically robust devils and retain wild-behaviours. These devils may also one day be called upon for reintroduced to Tasmania.
Q: Why can’t we just keep Tasmanian devils in captivity for now?
A: Recent research has shown that wild-born female Tasmanian devils produce significantly more joeys per female than captive born females. For zoo-born females, the number of joeys produced per female had a downward trend between respective generations in captivity. Essentially this means that devils are having reduced breeding success as each successive generation remains in captivity. This finding has serious and significant implications for devils if wild stock cannot be augmented into the existing captive Tasmanian devil insurance population.
Q: Is there Tasmanian DFTD in any devils held in captivity on mainland Australia?
A: No. There is no DFTD in any Tassie devils held on mainland Australia. All devils transported to mainland Australia from Tasmania have been quarantined and are disease-free.
Q: What about Dingoes? Will a release of Tasmanian devils affect dingo populations?
A: Devils will not be released at the detriment of dingoes. While dingoes also may play a key role in regulating overabundant herbivores and now act as a surrogate species for the now extinct thylacine, there are many landscapes that are absent from dingoes where devils could be reintroduced to. Dingoes may also be able to co-exist with devils – this interaction is untested, and a trial reintroduction to the mainland may in time help answer this important question.
Q: But haven’t mainland ecosystems adapted to life without the Tasmanian devil?
A: We know that the behaviour of species within ecosystems can change rapidly when a devils are introduced or removed. In evolutionary terms, the devil has only been absent from the mainland for the blink of an eye, and the far greater landscape impact variable than the length of time is the loss or introduction of a species. For example, we know that following the functional extinction of the Tasmanian devil in eastern Tasmania, the habits of brushtail possums changed within the course of only a few years. It would be anticipated that if devils were returned to mainland ecosystems, our wildlife would quickly re-learn avoidance behaviours that evolved over millennia in synchronicity with the evolution of the devil on mainland Australia. A trial mainland reintroduction would also seek to answer some of the questions scientists have on intraguild predation and competition as well as interspecific relationships between devils and our native Australian fauna.
Q: What about feral predators? Could Tasmanian devils be killed by foxes or feral cats?
A: Possibly. Adult foxes and feral cats may prey on juvenile devils. We know from Tasmania that devils can survive in environments where feral cats are established, however we don’t know the effect of foxes on devils. This interaction may be key to the success of providing a natural control for foxes on the mainland, if adult devils were able to prey on fox cubs whilst avoid being killed by adult foxes.
Q: What about feral predators? Could Tasmanian devils kill foxes or feral cats?
A: Possibly. This is possibly the most intriguing question that a trial release would hope to answer. Adult Tasmanian devils may prey on the cubs and kittens of foxes and feral cats. Anecdotally, it has been suggested that fox incursions into Tasmania may have been prevented by devils preying on fox cubs – however the interaction between foxes and devils has never been observed or tested.
Competition, rather than predation may also play a role in reducing fox and feral cat numbers. If devils are able to generate a ‘climate of fear’, foxes and feral cats may find it harder to survive in an environment where the devil is present.
Q: What about threatened native species? Could Tasmanian devils increase pressure on our wildlife?
A: Site suitability selection for potential trial release sites will include rigorous ecological baseline surveying, to determine the presence of threatened species. The impact of devils on these species will be monitored, and devils will be removed from sites if it is determined there is a negative ecological effect. It should be remembered however, that devils evolved over hundreds of thousands of years in synchronicity with Australia’s other native plant and animal species. Furthermore, foxes and cats will be reduced at sites prior to trial releases, which will provide an immediate dampening of the effect of predation and competition on native species by both feral predators as well as devils.
Q: What about the interaction between our Tiger Quolls and Tasmanian devils?
A: Devils and quolls are both apex predators that have diverged to occupy different niches. Competition between these species has been reduced through evolution of canine tooth size, and therefore prey size. These species will coexist.
Q: What are some reasons that some people might not be in favour of a trial release on the mainland?
One suggestion that has been made by commentators on the issue, is that having devils on the mainland might impact on Tasmania’s tourism sector. This concept greatly undersells what Tasmania has to offer and why people visit Tasmania.
In a poll of almost 400 individuals taken by Rewilding Australia, over 93% of Tasmanian visitors stated that their primary reasons for visiting was to undertake an outdoor activity (i.e. hiking or adventure activity), to experience Tasmanian wildlife in general, and to experience the arts and culture of Tasmania.
In summary, while people may go to Tasmania with a hope they’ll see a Tassie devil, they don’t go ‘to see’ a Tassie devil.
Furthermore, over 85% of those surveyed thought it was a great idea to trial a reintroduction of the Tasmanian devil to the mainland, with another 13% stating they could be convinced if there were reasonable grounds. That’s less than 1.5% of those surveyed who think a reintroduction trial is a bad concept.
But here is the primary reason that people should worry less about losing the devil from Tasmania, and more about losing the devil from our entire planet. When a population of animals is restricted to a relatively small range that is not separated by geographical barriers (for example, a barrier such as Bass Strait) it is far more likely for that species to become extinct. By having two geographically isolated colonies of devils, then devils have a higher chance of avoiding an extinction event. For example, if the devil had only inhabited the mainland of Australia, it would have become lost to our planet forever when it disappeared. Instead the Tasmanian population acted as an ‘ark’. It is time for mainland Australia to repay the favour to Tasmania, and help protect this unique and threatened Australian species.
Q: Might devils on the mainland interfere with sheep production?
A: Long term sheep farming families Rewilding Australia has spoken to in devil habitat have reported no predation. A good resource on this issue can be found at the Tasmanian Department of Primary Industries, Parks, Water and Environment website.
Q: Where could the devils for the trials come from?
A: Devil Ark, Australia’s largest captive breeding facility is capable of producing far more devils than can be placed within the insurance program. 35 other zoos and sanctuaries also hold devils as part of the insurance program for the species and could also participate in a trial mainland reintroduction. Excess devils surplus to the requirements of the Save the Tasmanian Devil Program could be utilised for a trial release.
Q: Will there be economic benefits to natural feral predator control?
Based on figures from 2004, every year Australia spends more than 486 million dollars on controlling feral foxes, cats and rabbits alone. If Tasmanian devils on mainland Australia were able to reduce the intensity of feral pest control by only a tiny margin, the economic benefits to Australia could be significant.
Recent modelling by researchers at the University of NSW suggest that Tasmanian devils may play a role in managing overabundant native herbivores while also reducing the impact of feral pest species. Surely it is worth trialling the reintroduction of a native species that evolved on the mainland, to determine its potential benefit to both the economy and the environment.
Useful Supporting Resources
Dr Euan Ritchie – Senior Lecturer, Centre for Integrative Ecology, School of Life and Environmental Sciences, Deakin University
Associate Professor Mike Letnic and PhD Candidate Daniel Hunter, School of Biological, Earth and Environmental Sciences, University of NSW
Australian Wildlife Conservancy Chief Scientist Sarah Legge
Daniel Hunter, Thomas Britz, School of Mathematics and Statistics, University of New South Wales, Dr Menna Jones, Department of Zoology, University of Tasmania, Mike Letnic
Tracey Hollings, University of Tasmania, Dr Menna Jones, Nick Mooney, Independent Research Professional, Hamish McCallum, Griffith University, School of Environment
Rewilding Australia Inc.
Rewilding Australia Inc.
For further information please contact