To safeguard the endangered Tasmanian devil's population, researchers established a small number of individuals on an Australian island off the coast of Tasmania in 2012. However, since the devils' introduction to the island, their presence has wreaked havoc on native bird populations and may have eliminated an entire colony of little penguins, according to a report released by BirdLife Tasmania.
Tasmanian devils (Sarcophilus harrisii), the world's largest carnivorous marsupial, were placed on Maria Island, east of Tasmania, to shelter the species from a contagious facial cancer called Devil Facial Tumor Disease (DFTD), reports Isaac Schultz for Gizmodo. The Australian and Tasmanian governments made the effort under the Save the Tasmanian Devil Program (STDP), established in 2003, to help stop the marsupials' decline due to the disease and road strikes and repopulate the species, reports the BBC.
The cancer is transmissible and spreads through bites when Tasmanian devils fight each other for food or mates. Large tumors appear anywhere on the animals' face and neck, including the inside of their mouths. Once the cancer is visible, the devils usually die within a few months. DFTD has wiped out 90 percent of the marsupial's population numbers since it was first spotted in 1996, per Gizmodo. Currently, Tasmanian devils are listed as endangered on the IUCN Red List of Threatened Species.
Tasmanian devils without DFTD were placed on Maria Island to create a healthy population and conserve the endangered species, reports Harry Baker for Live Science. Little penguin (Eudyptula minor) populations began to dwindle when 28 Tasmanian devils were established on the island, but a recent survey found that the penguins completely disappeared, Live Science reports. The flightless bird's numbers in 2012 consisted of 3,000 breeding pairs.
"Losing 3,000 pairs of penguins from an island that is a national park that should be a refuge for this species basically is a major blow," Eric Woehler, an ornithologist at the University of Tasmania, tells the Independent's Matt Mathers.
Aside from Tasmania devils decimating little penguins, a study published in August 2020 found that the devils were also affecting colonies of short-tailed shearwaters on Maria Island, the Guardian reports. In the same study, researchers found that Tasmanian devils outcompeted other predators like possums and cats, Gizmodo reports.
Since their placement on the island, the devils' population increased to 100 by 2016, reports Donna Lu for the Guardian. Experts say removing the devils may not cause detrimental effects to new marsupial populations and may encourage little penguin populations to return to Maria Island, Live Science reports.
"You have a range of insurance populations around Tasmania and on the mainland of Australia [now]," Woehler tells the Guardian. "I would argue that the removal of one insurance population will not have any adverse consequences for the devil."
In 2020, a study published in Science suggested that the facial tumor outbreak is spreading at a slower rate, and Tasmanian devil populations are more likely to survive. It's possible the devils' introduction to Maria Island may not have been necessary and happened because the disease was not yet fully understood, reports the Guardian.
A spokesperson for the Tasmanian government told the Guardian that their STDP program monitored the marsupials' populations and will continue to do so.
"All effective conservation programs are adaptive, and the STDP will continue to evolve in line with new knowledge in science and emerging priorities," the spokesperson tells the Guardian. "This also applies to Maria Island, where active monitoring and management occurs, and Maria Island remains an important part of the broader devil program to help restore and maintain an enduring and resilient wild devil population in Tasmania."