Humans are not the only animal that can wipe out an entire species' population. Tasmanian devils
(Sarcophilus harrisii) were introduced by humans to Maria Island off the coast of Tasmania in 2012-13. Twenty-eight of the marsupials quickly increased to 100 by 2016 as an "insurance' population free of the deadly facial cancer devastating mainland populations. Maria Island was also home to 3,000 breeding pairs of little penguins (
Eudyptula minor);+ that is before the carnivorous devils wiped them out. Dr Eric Woehler, the convenor of BirdLife Tasmania said “Every time humans have deliberately or accidentally introduced mammals to oceanic islands, there’s always been the same outcome … a catastrophic impact on one or more bird species,” He called the loss of the peguin population in a national park a major blow to conservation. Shearwater population on the island has also been negatively impacted. But because the little penguin is flightless and rather awkward on land, the devils eliminated them first. Offshore islands are especially important for penguin survival since they are relatively isolated from human interference.
Recent research (2020) shows that the facial cancer that was feared would wipe out Tasmania's devils is unlikely to extinguish the species as the disease spread has slowed. Dr. Woehler says the translocation of endangered devils to Maria despite the expected negative impacts on resident fauna was justified because at the time the impact of the facial tumor disease was not well understood. The island has Tasmanian pademelons, Forester kangaroos and Bennett’s wallabies, whose populations were previously managed by annual culls. However, devils are opportunistic predators and the little penguins proved too easy a prey.
The research shows devils have succeeded in gaining a genetic edge against the viral cancer known as DFTD (Devil Facial Tumor Disease) Infection rates (RÉ›) has dropped to around 1 from a high of 3.5. Since the disease is transmitted by biting, lower population densities may be contributing to the decline in infections. The authors conclude devils rapidly evolved in a short time to tolerate and possibly resist the cancer, and could now exist in a “steady state” with it. The study expands on earlier work led by Dr Rodrigo Hamede, a disease ecologist at the University of Tasmania, which suggested a handful of devils had developed a natural immune response to the disease.There are about 10,000 devils in the wild, with captive breeding programs seeking to reintroduce the devil to mainland Australia; so we should expect to have the rambunctious devils around to enjoy in the future.
