Why we released 24 eastern quolls at The Quoin
Lutruwita/Tasmania’s eastern quoll population has experienced almost two decades of decline, the root cause of which remains unclear.
Quolls are the charismatic, spotty carnivores of the marsupial world. Their spots act as fantastic disruptive camouflage, making them difficult to find in the forests, rocky outcrops and grasslands that provide their habitat across Australia and New Guinea.
Australia is home to four species: spotted-tailed quolls, eastern quolls, western quolls and northern quolls. Lutruwita/Tasmania is lucky enough to provide a refuge to two of these species, with both spotted-tail quolls (Dasyurus maculatus) and eastern quolls (Dasyurus viverrinus) found on the island. Of the two species, the eastern quoll is under the greatest threat in Tasmania.
Once found across a broad swathe of south-eastern Australia, eastern quolls were declared extinct on the mainland in the 1960s, and are now restricted to reintroduced populations in fenced sanctuaries. Their mainland extinction was preceded by rapid, steep declines, largely attributed to direct human pressure and predation by invasive predators.
Back in Tasmania, surveys conducted by the state government show eastern quolls have experienced almost two decades of decline, with a particularly steep downward trend in the Midlands and East Coast regions. Periods of unsuitable climate (long, wet winters) around the turn of the century have been hypothesised as a key driver behind the initial drop, but continuing losses are likely due to a complex combination of interacting factors. The root cause of the population decline remains unclear.
A partnership forged by an Australian Research Council Linkage grant, and also supported via the Elsie Cameron Foundation and the National Environmental Science Program (NESP) Resilient Landscapes Hub, is looking to clear up some of the uncertainty, and boost the long-term prospects of eastern quolls both in Tasmania and on mainland Australia. Together the University of Tasmania, the Tasmanian Land Conservancy and WWF Australia, with the committed support of the Tasmanian Quoll Conservation Program, have been investigating the drivers of eastern quoll decline in Tasmania. Networks of camera traps, and a series of targeted surveys, have allowed us to paint a picture of an eastern quoll’s potential threats, possible prey and overall habitat structure.
Understanding how these factors vary across the landscape has allowed us to pursue some important conservation work — actively doing something about these declines by supplementing flagging quoll populations in areas with minimal ongoing potential threats.
The Quoin
The Quoin was selected as a research site for the eastern quoll project in 2023, with the subsequent deployment of 30 cameras across the landscape.
This grid was extended with an additional 20 cameras in 2024, providing researchers with critical information such as the diversity and relative abundance of potential predators, competitors and prey species of importance to eastern quolls.
Since their deployment, these cameras have captured a whopping 1.5 million images. Recorded species include a wide range of both prey and predators such as eastern barred bandicoots, spotted-tail quolls and Tasmanian devils. The presence of prey species, along with invertebrate survey data indicated sufficient food availability to support a larger eastern quoll population than currently present.
These findings resulted in The Quoin being selected as the first translocation site of the project.
Eastern quoll translocation
Translocations form a key component of this project, to both augment local populations and assist in determining the factors underlying Tasmanian declines. With a broad range of habitat types, The Quoin provided the ideal opportunity to explore eastern quoll suitability at a landscape scale.
With the support of the Tasmanian Quoll Conservation Program (made up in part by Bonorong Wildlife Sanctuary, Devils@Cradle, East Coast Natureworld and Trowunna Wildlife Sanctuary) we translocated 24 eastern quolls to The Quoin in February 2025.
Before being released, each quoll underwent behavioural and health assessments to ascertain their suitability and hopefully note any key characteristics that affect survival in the wild. During this process, VHF transmitters were attached to allow researchers to keep tabs on the quolls’ movements over the coming months.
Monitoring
Transmitters allow researchers to track quolls to their den sites and further understand the habitat preferences of each individual.
PhD candidates Erin Thomas and Sophia Jackson spent countless hours tracking these devices down across The Quoin and neighbouring properties, with the aim of identifying what habitat the quolls gravitate towards, thereby informing future translocation efforts. There is much analysis to be done yet, but some early examples of den sites chosen by translocated quolls include hollow logs, small burrows in the earth and gaps amongst rock piles.
In addition to preferred denning locations, tracking translocated eastern quolls provides us with information on how they move in the landscape. Tracking data can help us record how and where quolls disperse upon release, in addition to their interactions with other translocated quolls and their wild-born counterparts. The map below shows the movements of each quoll over the first two months post-translocation, indicating moderate-level dispersal and a possible preference for open grasslands. Once combined with data from future translocations, this kind of information will help inform future translocations by building a more detailed understanding of habitat use.
In addition to VHF transmitters, our network of 50 camera traps remain in situ to identify changes in the relative abundance of eastern quolls, along with other key species such as spotted-tail quolls, Tasmanian devils and small prey. Cameras are also placed on select den sites and supplementary feeding stations to monitor activity and interactions between individuals. The huge volume of photographic data provides great insight into which species are using the feeders and if there is a possible correlation between providing additional food options and the survivability of translocated quolls.
VHF transmitters and camera traps also play a key role in assisting researchers to successfully trap quolls for additional monitoring. For the first few months post-release, each quoll is targeted once per fortnight for a general health check. In exchange for a meal of cat food, the quoll is examined and weighed to ensure they have adapted well to life in the wild, before being released back into the landscape.
Moving forward, the release cohort will continue to be trapped intermittently to monitor breeding success and to gain an understanding of genetic flow between the wild and translocated populations.
What’s next?
Over the coming years researchers will continue to monitor the eastern quoll population at The Quoin. Although VHF transmitters have now been removed, cameras will remain in place and live trapping will be conducted at key times of the year, such as the summer dispersal season (Dec/Jan) when there is an increase in the number of individuals moving through the area. We look forward to seeing how the translocated quolls contribute to the local population in years to come.
The big picture
The decline of eastern quolls in the Tasmanian landscape leaves a large hole.
Quolls fill the role of a mesopredator in the ecosystem (basically a rung below top-order predators such as Tasmanian devils or dingoes). This means they play a critical role in regulating the populations of species further down the ecosystem ladder, such as invertebrate and small mammal populations, which can get out of whack when quolls are absent in the landscape.
Similarly, the Devil Facial Tumour Disease, which induced declines of the Tasmanian devil, is likely to have had knock-on effects for eastern quolls that aren’t necessarily positive. With fewer devils in the landscape, feral cats face less predation — a ‘release’ effect that can increase their impact on quolls through both predation and competition. These pressures are less severe when eastern quoll populations are higher.
For these reasons and more, a healthy ecosystem is one that contains lots of quolls!
Historical records paint vivid pictures of grasslands and woodlands bouncing with eastern quolls, something that’s all too rare in modern Australia. Anything we can do to bring our ecosystems closer to that picture is a step in the right direction.
Partners
This project wouldn’t be possible without the contributions of our partner organisations. We are very fortunate to have the support of the following to facilitate this research.
Tasmanian Quoll Conservation Program
This guest edition of The Quoin Journal was written by: Morrigan Guinane and Dr David Hamilton
And edited by: Bronte McHenry, Karina West and Lisa Miller
The Quoin is a living laboratory, where we develop and deploy technologies, products and practices to accelerate regeneration at scale.
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