Speak of the Devil
More than 90% of wild Tasmanian Devils have been wiped out by an infectious disease: is there any hope left for the species?
Ever Skype with the devil before? I have. He was not your classic, satanic devil, but a Tasmanian devil. His name was Rubin, and he is one of about 600 devils in captivity. Even fewer are in the wild, thanks to a bizarre and so far untreatable infectious cancer that has wiped out more than 90 percent of the wild population in just 20 years.
Rubin is four years old and lives by himself in a bachelor pad at a breeding facility at Trowunna Wildlife Park in Tasmania, an island that’s part of Australia and the eponymous stronghold of the Tasmanian devil. Rubin’s sitting on top of a large box on a field of lush grass dotted with various play structures that your average pre-schooler would find irresistible. “They like to get up high,” explains Drew Lee, my virtual guide, “It’s a dominance thing.” Rubin knows we are watching him. His compact, portly body — adult devils resemble 15-pound black rats with a stylish white stripe across their chests — is angled toward us, tracking the conversation.
Lee, the man who made it possible for me to get some face time with a devil, is a wildlife biologist at the Tasmanian Department of Primary Industries, Parks, Water and Environment. He studies devil ecology, while also helping to manage what’s known as the “insurance population” — a group of devils taken into captivity as a safety measure. So few devils survive in the wild that a captive population is the only insurance against extinction.
As Lee begins to tell me about his work, Rubin crouches down while keeping his dark eyes trained on us. He has the right idea. The story of his species is a complex one that merits a good sit-down. Their diabolical namesake suffered from an existential dilemma, but the Tasmanian devils are suffering from a more tangible crisis that also requires salvation.
As we find ourselves in the terrifying environs of what some are calling the “Anthropocene”– an age defined by human-driven change and extinctions–conservationists across the world are struggling to save species while dealing with limited funding, political backlash, and imperfect understanding. The diffuse nature of these concerns makes the process singularly difficult. It often begs the question, is this species worth saving? Or should we focus our efforts somewhere else?
Unlike some species that occupy very small and fragile ecological niches, devils roam far and wide, and can and do eat almost everything they come across. They even eat bones; carcasses are a favorite.
The Tasmanian devil “has always been savable,” says David Pemberton, who manages the government-run Save the Tasmanian Devil Program, founded in 2003. He explains that the devil, unlike many other threatened species, is able to deal with external threats. Sharks, for example, have long and complex life histories that make reproduction a challenge, but a single female devil can birth more than a dozen young in her lifetime. And unlike some species that occupy very small and fragile ecological niches, devils roam far and wide, and can and do eat almost everything they come across. They even eat bones; carcasses are a favorite.
This robust combination of hardy diet and high productivity makes the devil one tough demon. The only thing bringing the little guy down is an internal malfunction. Devil Facial Tumor Disease, or DFTD, is a transmissible cancer that showed up in the population two decades ago. Research has revealed that the cancer began with a single female devil, long dead, but whose horrifying legacy lives on in her unlucky descendants.
The tumors on devil faces today are the disembodied fragments of the original female. The she-devil lives on, zombie-style.
In humans, infectious cancers are rare. Instead, cancers usually develop independently, a consequence of mutations and runaway cell division in the victim’s body. Not DFTD. The tumors on devil faces today are the disembodied fragments of the original female. The she-devil lives on, zombie-style.
The cancer has “become an independent entity,” marvels Cambridge University cancer researcher Dr. Elizabeth Murchison. It spreads because devils like to bite and spit on each other. There is only one other important known contagious cancer in the animal kingdom: a venereal disease plaguing dogs that also originated in a thousands-year old ancestor. And only DFTD threatens to drive an entire species to extinction.
If its iconic stature, carnivorous marsupial status and banshee screech are not enough to make the devil special, then surely their devil’s own hell does. What makes DFTD monstrous, besides the harrowing physical aspects, is that the disease has no apparent weakness. There is no cure or vaccine, though a small team of scientists and researchers funded by various institutions, including Pemberton’s program, is trying to change that.
Lately, there has been some progress. Hannah Siddle, a colleague of Murchison’s at the University of Southampton, recently solved one of DFTD’s most vexing mysteries: how it manages to bypass each devil’s immune system without a struggle. With the help of Jim Kaufman and his lab at the Department of Pathology at Cambridge, Siddle discovered that DFTD cells lack MHC molecules, the distinct “markers” on cells that bind to peptides and trigger immune response. DFTD cells “are not expressing these markers at all,” says Murchison. Thus the disease can pass through organ walls undetected, a ghost in the system.
But the jig may be up for DFTD. Back in the lab, Siddle and her colleagues “found that we could actually turn MHC molecules back on.” With this knowledge in hand, a team in Hobart, Australia led by immunologist Greg Woods is attempting to develop a peptide vaccine to DFTD. If successful, this vaccine could be administered to non-diseased devils, saving them from infection, though their young would still be vulnerable to disease. It’s not a cure-all, but it is a major step at a relatively low price–Siddle says such a vaccine would be “reasonably cheap to produce.”
The search for a vaccine is urgent because the captive devils are so vulnerable. As an island species with a confined range, devils have never had a lot of genetic diversity. Back in the mid-1990s, when the disease first appeared, scared scientists grabbed as many healthy devils from the wild as they could, without necessarily capturing genetically important specimens, Pemberton acknowledged. So while some news stories and even the Save the Tasmanian Devil Program’s own website claim that the insurance population carries 98 percent — some even say 99 percent — of the species’ genetic diversity, that’s not correct. The captive population actually holds 98 percent of the genetic diversity of the founder population, those individuals collected at the start of the program, but not of the entire devil population. As such, devils today have less genetic diversity than they did 20 years ago and are even more vulnerable to disease.
Rubin sports a white scar on his rump from a cyst that has recently been removed, but it isn’t from DFTD, it’s just another indication that devils are prone to cancers and growths in general, Drew Lee explains. But their vulnerability doesn’t necessarily mean the species is doomed. Because devils tend to live much longer in captivity, illnesses that almost never appear in the wild are showing up in the insurance population. In this way, the captive devils are much like humans of the modern era, who are gifted with long life, but also cursed with cancer and heart disease.
There are other worries, too, besides disease. Close study of captive individuals suggests that some devils are losing wild behaviors.
“Captive breeding is the ugly sister of conservation,” says Tim Faulkner, general manager of Devil Ark, an Australian reptile park and captive breeding center. Fortunately, devils reintroduced into the wild do regain wild behavior- it takes about six months, according to Lee. Back in 2012, a cohort of devils was released onto Maria Island, and they have since thrived. More releases are planned for next year on other islands and peninsulas around Tasmania. The core goal is “the long-term survival of the devil in the wild,” affirms Faulkner. Still, for the devil, captive breeding constitutes a crucial lifeline. If DFTD kills the species in the wild, the insurance population can step in.
What’s surprising to many devil experts is that the wild population is persisting more than two decades after the appearance of DFTD. About 10 percent of the 1990 population continues to survive, which is why Lee and others do not think DFTD alone will lead to extinction, “It’s disease that’ll take them to the brink, and then it’ll just take something else that in all other circumstances wouldn’t have been too much of a worry, but because they are already so reduced, that’s probably where you’ll see those localized extinctions,” Lee says. Exactly what that “something else” might be is unknown, but there are growing concerns over threats like road kill and land clearing for development and mining.
“If we can’t save the Tasmanian devil, what can we save?”
Perhaps the greatest asset the devils possess is their universal appeal to the island’s dominant species, Homo sapiens. Lee calls the Tasmanian devil issue “apolitical.” It has become a rallying cry for all levels of Tasmanian and Australian society, differentiating devil conservation from other efforts that are much more partisan. “It’s our Tasmanian devil,” proudly asserts Pemberton. No one down under wants another thylacine — the wolf-like “Tasmanian tiger” that blinked out more than a century ago.
But government funding is drying up, as other concerns supersede the devil issue– Pemberton says there’s only enough left for three more years of conservation work. To quantify, Pemberton thinks that the devil will need $5.5 million and ten more years to escape the brink. Overseas support will be critical. The San Diego Zoo has been providing financial and technical support to the devils for years. “If we can’t save the Tasmanian devil, what can we save?” explains Ron Swaisgood, director of applied animal ecology at the San Diego Zoo. Other groups have gotten involved, too. The Texas-based nonprofit Global Wildlife Conservation recently began a campaign to raise awareness and funding.
The support may be coming just in time, given that devils are at an all time low, once inconsequential threats like roadkill are now monumental. Pemberton says he’s “cautiously optimistic,” but the truth is that no one can be confident about the devil’s future. “We just don’t know what’s going to happen,” admits Faulkner.
Before a sudden rain shower forces Lee to move our Skype conversation into his car, my last glimpse of Rubin is of him steadily butt-dragging across the grass in a final show of territoriality for his audience on the other side of the world. Rubin’s comic display brings to mind the words of another hellion: “Hell is empty and all the devils are here,” said Shakespeare. For now, anyway.
