Once the biggest success story in Australian conservation, woylies are again critically endangered, leaving scientists scratching their heads.

Story By Ken Eastwood

There should be a new wild rollercoaster ride in Western Australia called “the woylie”. Once soaring high as the best example of Australians rescuing a species from extinction, woylies are once again critically endangered, their numbers having plummeted by about 90 percent in the past five years – and scientists don’t know why. “I can’t tell you how many days I’ve lost sleep over it,” says Dr Adrian Wayne from Western Australia’s Department of Environment and Conservation (DEC), the chief investigator in the Woylie Research Conservation Project.
Woylies, or brush-tailed bettongs, are a small rat-kangaroo that were found across two-thirds of Australia prior to European settlement. Like many small native species, they declined as habitat was removed and introduced animals, such as foxes and cats, feasted on the meal-sized 30-centimetre-high marsupials.
But in 1996, the woylie became the first species to be taken off the endangered list because its numbers had bounced back so well after 1080 was found to be an effective way to bait foxes. Woylies were re-introduced to many areas they previously lived. “It was the pin-up boy of conservation because it showed we can turn these things around,” Adrian says.
A decade later, researchers started noticing a rapid decline in woylie populations – a decline far more dramatic than that affecting Tasmanian devils – and the species is now critically endangered. “We’re looking at about a 90 percent decline in the species over five years – the Tassie devil was about a 60 percent decline over 15 years,” Adrian says. “This outstrips anything that most people would be aware of – this one’s right out of the box.” For example, in the Upper Warren, WA, bordered by Boyup Brook, Manjimup and Bridgetown, the largest wild population had reached an estimated 240,000 woylies a decade ago, but is now down to about 11,000.
Adrian says that researchers also didn’t really know where to start looking for the culprit. “With devils, they’ve got big ugly tumours on their faces to give them a clue – we seem to be dealing with something much more secretive,” he says. “I thought I’d just walk out into the bush and trip over the answer.”

This story excerpt is from Issue #77

Outback Magazine: June/July 2011