Extinction once seemed inevitable for the Tasmanian devil, but on an expedition to the state’s remote southwest, researchers made a discovery that could help protect the species.
Dr Carolyn Hogg was walking over hard, spiky rock, with Tasmanian devil traps strapped to her back, in a remote part of the island state’s wilderness when she felt something give. The sole of one of her hiking boots had snapped. It was the first day of a week-long expedition to search for Tasmanian devils that could prove key to the survival of the disease-stricken species.
Hogg, a population biologist and research manager with the University of Sydney’s Australasian Wildlife Genomics Group , patched her boot up with plastic and duct tape, strapped the long pipe traps on again, and set back out.
By the end of the trip, she and the team had walked 120 kilometres in search of the endangered animal, baiting traps and gathering data. It was worth it: the crowdfunded expedition to Tasmania’s southwest, she says, has "given us the first evidence that there are devils down there and those devils don’t have disease. That’s huge."
The disease threatening the devil
The Tasmanian and federal governments have invested millions in the race to find a solution to devil facial tumour disease (DFTD), which has decimated the species. The University’s Australasian Wildlife Genomics Group, which specialises in immunogenetics and conservation genetics, is playing a major role.
One of the questions the University’s researchers have already answered is how this contagious cancer is able to infect devils in the first place. "Why isn’t the devil’s immune system recognising that the cancer has entered its body?" says Hogg. "The reason is that DFTD is able to turn off the receptor cells that allow the devil’s immune system to see it. It is basically hiding from the devil’s immune system."
DFTD cannot be cured. It spreads when the animals bite each other during mating and fighting. Devils were already facing the same modern threats as other wildlife, such as roads, domestic animals and habitat loss. But the species is even more vulnerable than most because of its low genetic diversity. With the population devastated by disease, the risk of inbreeding is heightened.
The expedition has given us the first evidence that there are devils down there and those devils don’t have disease. That’s huge.
Preserving genetic diversity
The main strategy to retain genetic diversity in the species is an "insurance population". In 2006, young devils were brought in from the wild as a safeguard against the species’ extinction. There are now about 600 animals in the insurance population, living in 35 zoos and areas including Tasmania’s Maria Island and the fenced-off Forestier Peninsula.
Hogg is the co-creator of an algorithm that maximises devil pairings for gene diversity based on their genetics and where they were trapped. But even with this tool and 600 devils in the insurance population, concerns remained that genetic diversity was too low and there were no more new variants to be found.
That’s why the field trip into the wilderness was so exciting. University researchers had spent a year genotyping 87 devil scats that had been collected throughout the state’s southwest by a group of intrepid rangers and volunteers. Analysis confirmed the scats had come from devils and that some of them had different genetic variants from anything seen before.
What it couldn’t reveal was whether these animals were infected with DFTD. To find that out, the researchers needed to meet the devils face to face.
A crowdfunded mission
The University launched a crowdfunding campaign to fund an expedition to Nye Bay and Wreck Bay, two places in the Tasmanian wilderness accessible only by helicopter or on foot. More than 100 people donated $36,133, in amounts ranging from $5 to $30,000. A class of Year 2 students held a cake stall to raise money. Ohio’s Toledo Zoo agreed to fund helicopters to fly in two five-person teams. On September 17, the University will acknowledge these donors and others who have supported research and education, with the inaugural Thank You Day celebration.
The teams flew in with 1400 kilograms of gear, including 46 big cylinder devil traps and 100 kilograms of frozen vacuum-packed wallaby meat to bait them. A fridge was not included.
"It was a bit skanky by the end of the trip," says Hogg.
After the helicopter dropped Hogg and the rest of the team off in a tiny clearing - the only accessible space in the scrubby landscape - they set up camp by an icy creek. The bush was impenetrable, so the beach became their walking track. Scats and footprints guided them through sand dunes and into scrub where they would lay and bait the traps with a mix of wallaby, lamb, cat food and sardines.
Once the devils were caught, data collection began: measurements, microchipping, biopsies, disease checks. The researchers trapped six adult devils at Nye Bay and eight at Wreck Bay - all disease-free.
Fight for the future
It is too early to say whether any offspring from devils discovered on this expedition will be brought into the insurance population. But there are more areas to be explored in the quest to uncover unrepresented genetic diversity in the wild; Nye Bay and Wreck Bay were just two areas where devil scats were collected. There will be future expeditions to collect more data that could be used to boost the population and increase the species’ chance of survival.
"The more diversity you have, the better you are at adapting to change. So if we introduce devils and they live for a bit longer and they can breed for two breeding seasons instead of one, then that’s good," Hogg says.
Comparing devils released from the insurance population to those on wild sites will be "the final link", she says. "We need to know the answer to that question before we can make a long-term strategy to know how to manage the devils and disease in the landscape."
The plight of this cute carnivore has rallied zoos and scientists throughout Australia and around the world for 15 years. It’s complex work and a long-term commitment, but Hogg says it’s essential.
"Someone said to me, ’Why do you fight so hard to save the devil? Is it because they’re cute?’ and I said, ’No, I fight so hard to save the devil because they are the top-order carnivore in Tasmania.’ As soon as you lose the devils from the landscape, you will see an even greater increase in cats and - who knows - foxes may get a hold in Tasmania. We know these species have already decimated the wildlife of the mainland... If the devils go and the same thing happens in Tasmania, I think that would be a very sad day for our country as a whole."
The fight is far from over. The University collaborates with Cambridge University and the University of Tasmania’s Menzies Institute for Medical Research on work to preserve the species, while many others also contribute under the Save the Tasmanian Devil Program.
"Everyone we work with has the same goal, which is the best interests of the devil," says Hogg.
Thanks to the donor-funded expedition, the hunt for new genes is off to a promising start. There are more discoveries to be made on future trapping trips to Tasmania’s remote wilderness.
Next time, presumably, with a spare pair of hiking boots in Hogg’s backpack.
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