In Danger of Extinction Through Devil Facial Tumour Disease
The Tasmanian devil is an icon of Tasmania, an island state of Australia. It has been chosen as the symbol of the Tasmanian National Parks and Wildlife Service.
The Tasmanian devil is a squat, ungainly looking marsupial the size of a small but powerful dog. The forequarters and head are larger and stronger than the hindquarters, especially in the males. The front legs are longer than the back making the animal look very out of proportion. Devils have black fur with some having white markings on the hindquarters and a white bar across the chest.
For its size, it has the one of the most powerful bites of any mammal. It is renowned for its frenetic screeching and howling, especially when feeding. Several devils will converge on a carcase and wrangle fiercely over the spoils. The devil will gorge on its prey, consuming up to 40% of its own weight in around half an hour.
Some ten or fifteen years ago, the Tasmanian devil had made a good recovery from a very low population. It became fully protected by law in 1941. It was quite common and its future appeared secure. Its main threats had been man, either through poisoning, shooting and trapping or through destruction of habitat. Other threats included chemicals used in the forestry industry, competition from quolls and foxes, and feral cats and dogs.
But in the late 1990s, the Tassie devil was beset by a new problem – DFTD or devil facial tumour disease. By May 2008, they had been listed as endangered by the Threatened Species Protection Act 1995.
First seen in 1996, devil facial tumour disease is a debilitating cancerous sarcoma which is incurable, causing death three to five months after onset. The disease affects roughly 50% of wild devils. Ulcerated tumours develop around the jaws and head and the animal generally starves to death over a few months.
DFTD is a transmissible cancer, passed on from one animal to another. Devils have very low levels of genetic diversity and are more prone to infections of this type. They also have a chromosomal mutation unique among carnivores.
Devils occupying the west coast area and far north-west are the only animals currently free of the disease. In the north-east where signs of the disease were first noticed, average spotlight sightings have dropped roughly 95% from 1993 to 2005.
In 2006, DFTD was gazetted under the Animal Health Act as a List B notifiable disease.
The Government of Tasmania is undertaking programmes designed to reduce the impact of DFTD. As there is no cure, the authorities are attempting to remove sick animals and quarantine healthy ones. Field monitoring involves trapping devils within a defined area and working out the number affected. Areas are revisited regularly to monitor changes in numbers and/or any recovery of local populations. Diseased individuals are removed in the hope that this will help suppress the disease and allow healthy devils to mature and breed. Part of the strategy is to develop a group of healthy devils in captivity and to keep them isolated from the disease. The cost of preserving the Tasmanian devil has been estimated at $11 million.