Everyone knows the devil lives in Tasmania. It is a black and white marsupial with a thick tail and a cute face. And it is a creature which is fundamental for the equilibrium of the ecosystem of this Australian island. There, the species is at the top of the food chain and protects native Tasmanian animals from introduced invasive predators such as the European fox and feral cats and dogs.
But since the 1990s, a serious disease has been affecting the Tasmanian devils putting this iconic species, and the ecosystem their members help balance, under serious threat. Once abundant in the island, the devils have, since May 2009, been classified as endangered under Australia’s environmental law. The culprit is the devil facial tumor disease (DFTD), a contagious cancer which has reduced the devils’ population by about 85% since the first signs of the disease appeared in 1996. Captive breeding programs are key to prevent the extinction of this species.
The Tasmanian devils, nowadays found in the wild only in Tasmania, are the largest surviving carnivorous marsupials. They have big heads and muscular necks which allow them to have the strongest bite per unit of body mass of any living animal. They also have an incredible sense of smell and excellent hearing, and they can be ferocious when feeding.
While the description may resemble that of a violent, man-eating predator, the Tasmanian devil is a rather lovable animal. The creature may be the largest meat-lover marsupial, but it is only the size of a small dog, and its head is only big in comparison to its body. They do have an exceptionally strong bite and they don’t like being disturbed when feeding, but they pose no danger to humans. They do not attack people unless if defending themselves from attack or when trapped, and they would much rather run away than face a harmful fight.
The problem is when they open their mouths. When they mate or fight over food, the devils scream, cough and growl in a hellish manner.
But even this freakish behaviour has a peaceful explanation. The devils’ fierce noises and sharp sneezes are mainly bluff and are used to avert harmful fights.
These shy and mostly peaceful creatures do bite each other sometimes; it is part of their social interactions and it’s common during mating rituals. And it is precisely through bitting that the contagious disease that is threatening the devils spreads.
While the majority of cancers (including those afflicting humans) cannot be transmitted from one individual to another, the DFTD is a rare exception. It is one of only three types of contagious cancers and it is thought to have first originated in the nerve cells of a single devil.
Because the animals have long been part of the enclosed ecosystem of Tasmania, they have small genetic diversity. Hence, cancer cells transmitted from one individual to another are not rejected by the recipient’s immune system because the devils are “universal organ donors” to one another. Like a vital organ accepted by an individual if transplanted from a matching donor, the tumor cells are capable of establishing themselves in the devils’ bodies.
Once a devil is infected, small blemishes appear in and around its mouth, which quickly develop into large tumors. The cancer distorts the face and neck of the animal in such a way that it is soon unable to eat or drink. The devils typically die from starvation and dehydration within three months of the first symptoms.
No cure is yet available for DFTD and it is not feasible to use chemotherapy and surgery to treat the devils from a population point of view. To save the devil from extinction, initiatives such as the Save the Tasmanian Devil Program are in place to established an insurance population. As explained in the program’s website, about 3 years ago, disease-free animals “were sent to zoos and wildlife parks on the mainland of Australia to ensure they were isolated from wild devils. These animals formed the basis of a captive breeding program that can be used to re-establish populations.”
An important component of the program is the Devil Ark, an Australian Reptile Park initiative. The “Ark” is located in the Barrington Tops in New South Wales and it consists of large enclosures comprising natural bushland. The mission of this initiative is to “establish and maintain a genetically representative population of 1,000 or more Tasmanian devils in environmentally appropriate, ‘Tasmania-like’ conditions,” according to its website.
Talking to ABC News, Australian’s Reptile Park manager Mary Rayner stated that the “Devil Ark is actually seen as the linchpin of the entire program and the really only successful component of the program at the moment.”
With a lot resting on the initiative’s success, it is good news that it achieved a major milestone earlier this year: the first 30 animals bred in captivity at the Reptile Park were released to the Barrigton enclosures in January.
Tasmania waits to see how its devils will adjust to mainland conditions.