Facial tumours kill off Tasmanian devils

25 October 2003

A mysterious disease has wiped out 90 per cent of some populations of Tasmanian devils in the past three years. The facial tumours may have killed one third of the Australian island’s total population, a workshop in Tasmania heard last week.

Scientists fear that the problem is having knock-on effects on other species. Although Tasmanian devils are mainly scavengers, they also eat sick or small mammals and a range of invertebrates.

“These animals are very important in the whole ecology of Tasmania,” says the meeting’s organiser, Rob White from the University of Tasmania in Hobart. Reports suggest there are more than the usual number of carcasses of wild animals such as wallabies in areas where devil numbers have fallen.

And the number of cats seems to be increasing. Farmers have reported an increase in lambs aborted due to toxoplasmosis infection, which is carried by feral cats.


Retrovirus suspect

The first confirmed cases of facial tumours in Tasmanian devils were reported in the late 1990s. New studies suggest that 50,000 of the 150,000 devils alive a few years ago have died from the disease.

Tumours normally first appear around the jaw and neckline, and the consensus is that a retrovirus is the most likely cause. Scientists are trying to identify the agent involved.

Bryan Green, Tasmania’s environment minister, has organised a task force to tackle the problem. One suggestion is to boost numbers of devils held in captivity on mainland Australia to create a sustainable population. But as there is no test for the disease, transferring animals from Tasmania to Australia might contaminate mainland populations.

One positive piece of news is that in areas where devil numbers have plummeted, such as eastern Tasmania, the disease has a much lower transmission rate. Historical records also suggest there have been three previous massive declines in devil numbers in the past 140 years.

White says it Is possible that the disease is latent in the animals, and appears only above a certain population density. If so, the population might stabilise and eventually recover.