Tasmanian devils are the largest carnivorous marsupials in the world.
(Image credit: Shutterstock)
Critics call it a "predictable and avoidable outcome."
Conservationists in Tasmania may be ruing the decision to introduce endangered Tasmanian devils to a small island, after a new survey revealed that the alien invaders have wiped out the entire colony of little penguins living there.
Tasmanian devils (Sarcophilus harrisii), the world's largest carnivorous marsupials, were introduced to Maria Island — a 45-square-mile (116 square kilometers) island east of Tasmania — by the Tasmanian Department of Primary Industries, Parks, Water and Environment (DPIPWE) in 2012. The government agency hoped to create a new devil population to prevent the species from being wiped out by a deadly disease that has decimated their numbers in Tasmania.
However, the introduction of one species has meant the end of another: The new DPIPWE survey showed that the introduction of devils to the island wiped out 3,000 breeding pairs of little penguins (Eudyptula minor) living on the island, according to The Guardian.
Critics are now blaming the DPIPWE's decision to introduce the devils to Maria Island and the department's subsequent handling of the situation.
"This was a predictable and avoidable outcome," Eric Woehler, an ornithologist at the University of Tasmania and head of conservation group BirdLife Tasmania, told Live Science.
A pair of little penguins walk along a beach on mainland Tasmania.
(Image credit: Shutterstock)
Insurance policy
The International Union for Conservation of Nature, which maintains a list of threatened species, classifies the Tasmanian devil as endangered. One major threat to the species is the emergence of a rapidly transmissible form of cancer known as devil facial tumor disease, which has killed 90% of their population (which is mostly confined to Tasmania) since the disease first appeared in 1990, Live Science previously reported. DPIPWE scientists believed the only way to prevent a devil extinction was to create isolated populations of healthy individuals away from Tasmania.
In addition to keeping the devils safe on Maria Island, conservationists thought the transplanted individuals would help control the island's population of small predators, such as feral cats and possums; traditionally, officials had instead culled the predators to protect bird populations, according to The Guardian.
Similar attempts to introduce Tasmanian devils to the Australian mainland have been successful, and wild devils were recently born there for the first time in over 3,000 years, Live Science previously reported. However, the new population on Maria Island quickly grew out of control from 28 individuals, introduced between 2012 and 2013, to more than a hundred by 2016, according to The Guardian.
"The devil population is currently managed to achieve a population-size range of between 60-90 individuals," a DPIPWE spokesperson told Live Science, which they claim is the current estimated carrying capacity to "reduce impacts to island ecology."
Conservation nightmare
With that population boom, Tasmanian devils became the dominant predator on Maria Island, and some endemic species, such as the little penguin, could not adapt fast enough to survive the onslaught.
"The devils ate the adults and young," Woehler said. "The penguins that were not predated abandoned the colony in the face of predation pressure," most likely joining up with other colonies in Tasmania, Australia or even New Zealand.
The devils also killed and ate short-tailed shearwaters (Puffinus tenuirostris), significantly reducing the birds' numbers on Maria Island, according to a study published in 2020 in the journal Biological Conservation.
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