By Jack Ashby, on 17 February 2011
From April 2010 I spent about five months undertaking several zoological field projects across Australia. I worked with government agencies, universities and NGOs on conservation and ecology studies ranging from Tasmanian devil facial tumour disease, the effect of fire, rain and introduced predators on desert ecology and how to poison cats. This series of blog posts is a delayed account of my time in the field.
The next stage of my trip took me to Tasmania – my favourite place in the world. This was the research project I was most looking forward to – to trap Tasmanian devils and attempt to investigate a ray of hope in their battle with a contagious cancer. Devils are a badger-sized marsupial with a bit of a rep. They do hunt things up to the size of a small wallaby, but are best known for their skills at scavenging. They can eat every part of the carcass and have an impressive set of teeth. I once saw one climbing out of the anus of a dead pademelon, while two others were working their way in through the back.
Since my first visit, Tasmania has been my favourite place because you can’t walk anywhere outside of a (the) city centre – and not very far out of the centre – without encountering a wild mammal within an hour. The state’s tagline is “Tasmania: Your natural state”. Although I know the likelihood of it is minuscule, whenever I’m in the Tassie wilderness I can’t help but imagine seeing a thylacine running across my path, just for a second. Thylacines were once relatives of the devil – a large dog-sized pouched predator. Since humans deliberately tried to wipe them out (they incorrectly blamed them for killing sheep) none have been seen in the wild in 77 years.
I was working in the island’s Central Highlands with the University of Tasmania. The team researches Devil Facial Tumour Disease (DFTD). This contagious cancer first appeared in 1996 and has since spread across most of the island. Mortality in affected populations can reach 100% and obviously the number of devils – which live nowhere else – has crashed. Many experts say that extinction within 20 years is a distinct possibility.
Contagious cancer is a terrifying thought, and there are only a couple of known instances in nature. In this case DFTD is spread by the transmission of the cancer cells themselves – when infected devils bite another devil and a cancer cell rubs off, that devil is infected. As devils bite each other a lot, in feeding, mating and saying hello, this is a massive problem. Despite a lot of research, no cures have been found. One “immune” male was made a big deal of, and provoked a lot of research, but unfortunately after a few years he contracted the disease. It has been suggested that uninfected individuals are translocated to off-shore islands to form insurance populations. The problem with that is that these islands have their own endemic fauna, which would no doubt be massively affected by the introduction of the world’s largest marsupial carnivore.
Normally what happens is that within a year of a population being infected with DFTD nearly all of the adult devils are dead. Healthy devils would normally breed in their second year and live to seven or eight. Some diseased populations, consisting only of one year olds, have been found breeding early – evolution in action.
The point of this field study was to trap devils in a diseased population in which something funny is going on. Although DFTD first appeared four years ago, and many individuals are infected, aged devils are still being seen. This suggests that this population has some kind of immune advantage over the disease. The question is… why isn’t it spreading like it normally does? We had to monitor the disease in the population, and collect devil blood to try and find evidence of an antibody, histo-compatability complex, or some other magic bullet.
This first bit of trapping lasted a couple of weeks, so I’ll give a run down of what we did – how to trap a devil, and extract blood from a famously vicious creature with big teeth, for example – in future posts.
UPDATE: PART FIVE HERE