The Tasmanian devil (Sarcophilus harrisii) is a unique, carnivorous marsupial that is endemic to the island state of Tasmania, Australia. As the world’s largest surviving carnivorous marsupial, the devil holds an iconic status within the Australian ecosystem. This stocky, nocturnal scavenger plays an important ecological role as a clean-up crew, consuming carcasses and maintaining environmental health. For the past two decades, however, the species has faced severe conservation challenges that have drastically reduced its numbers in the wild.
The Current Population Status
The question of how many Tasmanian devils remain in the wild is difficult to answer with a single number due to their nocturnal habits, patchy distribution, and the ongoing impact of disease. Before the emergence of the major disease threat in the mid-1990s, the total wild population was estimated to be between 130,000 and 150,000 individuals across Tasmania. Recent estimates reflect a decline, with the total population now thought to be significantly lower than historical levels. Other sources provide a broader range of 10,000 to 25,000 mature individuals remaining in the wild, depending on the year and region being surveyed. In areas where the disease has been present the longest, local populations have seen declines of up to 80% or more.
The Cause of Decline Devil Facial Tumor Disease
The primary driver of the Tasmanian devil’s population crash is Devil Facial Tumor Disease (DFTD), a transmissible cancer. DFTD is an allograft, meaning the cancer cells themselves are transferred between individuals as a living parasite. Transmission occurs mainly through biting, which is common behavior during mating rituals and competitive feeding at carcasses. Once the cancer cells are transferred, they grow into tumors around the face and mouth, which interfere with feeding and typically lead to death from starvation within three to six months.
Two distinct strains of this contagious cancer have been identified: DFT1 and DFT2. DFT1 first appeared in northeastern Tasmania in 1996 and spread across most of the island, causing the widespread population collapse. DFT2, discovered in 2014, is genetically distinct and has a more limited geographic range, currently restricted to a peninsula in southern Tasmania.
Geographic Range and Habitat
The Tasmanian devil is endemic to Tasmania, having become extinct on the Australian mainland thousands of years ago. They occupy a wide variety of habitats across the island, including coastal heathland, dry and mixed sclerophyll forests, and agricultural lands. The species is highly adaptable, often foraging in the open and near roads, which unfortunately leads to high rates of roadkill.
The geography of the island has played a role in the spread of DFTD, linking location to vulnerability. Areas with higher devil density, such as the eastern half of the island, saw the most rapid and severe impact from the disease. Conversely, the rugged, isolated southwest region of Tasmania, which naturally supports lower devil densities, has experienced a much slower spread of the disease and in some parts remains disease-free.
Strategies for Survival
Conservation efforts are focused on two main pillars: establishing insurance populations and researching resistance and immunity. The “Insurance Population” program manages a genetically diverse, disease-free group of devils in captivity across zoos and wildlife sanctuaries in Australia. This population, which has grown to over 600 animals, safeguards the species’ genetic material against extinction in the wild. Disease-free populations have also been established in isolated, fenced-off peninsulas and on islands like Maria Island.
Scientists are simultaneously investigating the devil’s evolutionary response to the disease. Research has identified genetic changes in wild devils related to cancer and immune function, suggesting the species is rapidly evolving a degree of resistance in areas where the disease has been present for a long time. The development of a functional vaccine is also a major focus, with trials showing that experimental vaccines can successfully prime the devil’s immune system to recognize the cancer cells. The ultimate goal of these efforts is to manage and reintroduce disease-resistant or vaccinated devils back into Tasmania’s wild ecosystems to secure the species’ long-term survival.