The lack of unity over any single proposal is, in part, a testimony to the mystery of the facial cancer, and the speed with which it has swept across the island. "It's mind-boggling how rapidly a species can be fiercely affected," says Hesterman, who was studying devil reproduction when the outbreak gained wide notice in the scientific community. The first signs of the cancer, known as "devil facial tumour disease," appeared in 1996. Once a devil is infected, tumors that can be as large as tennis balls balloon from its face. Within a few months, the animal dies of starvation. "There's no sign of resistance," says Hesterman. "There's no sign of recovery."
Typically in nature, when a pathogen ricochets through a population in this manner, the disease begins to disappear once too few animals are left to transmit it. In a 2006 paper in PLoS Biology, McCallum and colleague Menna Jones write that, as far they know, no infection has ever driven its host to extinction. Perhaps because much of the cancer's transmission stems from biting that occurs during sexual interaction, however, this universal failsafe has not held firm. In areas of Tasmania that have been tracked since the first sightings, devil numbers have plunged by 90 percent. "There's no evidence of a decline drop-off," says McCallum. "If the population is dropping by 90 percent in ten years, you won't have much left in 20."
So far, researchers have no vaccine for the rare cancer, which they believe is caused not by a virus but by cells implanted through biting. (Only one other illness, a non-lethal disease in dogs, has similar characteristics.) One popular theory of how the cancer originated—that the pesticide known as 1080 contributed to its emergence—is largely refuted. That chemical is used widely by foresters in Tasmania. In 2005, DPIWE announced plans to test devils for toxins, including 1080. Those tests have yet to be conducted, according to an article in the April 29, 2007, Sunday Tasmanian.
The devil decline could enable the red fox population to establish on Tasmania—a prospect that Mooney sees as a worse threat than the cancer itself. The fox was introduced to Australia in the mid-19th century, and despite public doubts that it has landed on Tasmania, Mooney calls evidence for fox presence there "extremely convincing." Most likely, he says, devil populations suppressed a fox outburst to this point. "You take away devils, it's like taking wolves out of Yellowstone," says Mooney, referring to the disruption caused in the biological chain when gray wolves were removed from the U.S. national park.
If foxes do live on Tasmania, removing them could be extremely expensive, says conservationist Josh Donlan of Cornell University, who is familiar with the devil's plight. When Donlan participated in the removal of goats from the island of Santiago in the Galapagos, he says, it cost $5 million to remove the first 70,000 or so goats, and another million to get rid of the final 1,000. "And Tasmania," he says, "would be starting with the last ones."
Scientists do have another option: relocate the devil to free-range areas in mainland Australia. Of course, then Tasmania would lose jurisdiction over its eponymous species. And would a Tasmanian devil living anywhere but Tasmania be properly named? That question, however touchy, would likely be welcomed if it meant the devil had survived the current scare. "Every 50 devils we put somewhere is 50 devils that would have contracted the disease and died," says Hesterman. "If we leave them in the wild, we know what's going to happen to them."