Sydney

The deliberate introduction of foxes into Tasmania, the island off the southern coast of the Australian mainland, is threatening to devastate the island's unique ecology, wildlife biologists say.

At a conference in the Tasmanian city of Launceston earlier this month, fox and pest-control experts called for steps to eradicate the foxes before the breeding season begins in July. Unless action is taken before then, they say, the island's fox problem could get out of control.

Tasmania is the last refuge for a long list of species that have been wiped out in mainland Australia. Many of these are vulnerable to predation by foxes.

“The information that the authorities have received leaves no doubt that foxes were deliberately brought into Tasmania,” says Nick Mooney, a member of the state government's fox task force, which was set up last year when the problem was first identified. It is believed that the foxes were deliberately imported, perhaps by individuals who wanted new game to hunt or who were angered by the recent introduction of stricter gun-control laws. A police investigation is under way.

There are estimated to be at least a dozen foxes in the state, says Tony Peacock, chief executive of Australia's Pest Animal Control Cooperative Research Centre. “Unless action is taken to eradicate the foxes before the breeding season starts, the battle to keep Tasmania fox-free may be lost,” says Peacock, who says that an estimated 77 native species could be in jeopardy as a result.

Farmers, biologists and conservationists at the Launceston meeting agreed that the foxes should be eliminated by baiting them with sodium monofluroacetate — a poison better known to farmers as '1080' — in conjunction with shooting and trapping. Use of the bait is highly controversial in Tasmania, where conservationists object to farmers and foresters using it to control populations of native animals, such as opossums and wallabies, which graze on crops and tree seedlings. Biologists and wildlife managers are trying to work out how to present the bait in a form that will be accessible to foxes, but not to other native carnivores, which include marsupial species such as quolls and the Tasmanian devil.

Closer to breeding time, Roger Short, an expert in reproductive biology at the University of Melbourne, hopes to test the use of sterilized vixens carrying oestrogen implants — which keep them in constant oestrus or 'heat' — to lure male foxes, which will then be killed.