Bilby boom: breeding trial to reintroduce species to Mallee Cliffs national park shows signs of success | Conservation
Efforts to reintroduce bilbies to far south-west NSW are showing signs of success, with numbers climbing to almost 2,000, seven years after the first breeding attempt in Mallee Cliffs National Park.
Fifty “founder” bilbies, including 30 from Thistle Island off the coast of South Australia, were released into a fenced breeding area in 2019 in a bid to establish a wild population in the Mallee Cliffs habitat for the first time in a century.
Between 2021 and 2023, 107 bilbies were released from the breeding area into 9,570 hectares of fenced, predator-free habitat in the park. The Australian Wildlife Conservancy (AWC), which runs the conservation project with the state government, has conducted initial surveys and estimates the total population has now reached 1,840 bilbies.
“Excluding bilbies from the impacts of wild cats and foxes really allows them to thrive, reproduce in numbers and persist in the environment,” said Rachel Ladd, wildlife ecologist at AWC.
She said the project team “absolutely knew” a population boom was possible and it had been “wonderful” to see bilbies running around and turning over the dirt in the park.
Ladd said motion sensor cameras showed the animals had dispersed into the larger fenced area and dug burrows to the point where they now occupied most of the predator-free habitat.
“We capture them on 95% of our cameras, which alone is a strong indicator that the population has dispersed in the shelter and [is] using the full extent of protected habitat,” she said.
The greater bilby is listed as vulnerable under Australian wildlife laws and is only found in about 20% of its former range, in arid and semi-arid regions of the country.
The Mallee Cliffs Project is one of six large predator-free areas with bilby populations managed by the AWC.
Across properties in New South Wales, South Australia, Western Australia and the Northern Territory, the organization’s annual census in Bilby found the number increased from around 3,300 in 2025 to 5,300 in 2026. The result is more than four times the 2021 population estimate (1,230).
This includes around 1,830 bilbies in the Scotia Wildlife Reserve in south-west New South Wales, where the population is steadily recovering after a severe drought in 2018-19.
Ladd said the dryland nature made bilbies a boom-and-bust species, with census results reflecting better environmental conditions for breeding. She said population numbers are expected to fluctuate.
“In times of prosperity they are able to reproduce and increase their population relatively quickly and in times of drought their population declines,” she said.
“Depending on the drought, there may be accidents, but they persist and then rebuild their numbers.”
At Newhaven Wildlife Sanctuary, in the Ngalia Walpiri and Luritja region of the Northern Territory, the survey showed a rapid increase in numbers from 66 founding bilbies three and a half years ago to around 530, partly due to above-average rainfall. Ecologist Tim Henderson said bilbies – known as ecosystem engineers – were reshaping Newhaven’s landscape by feeding and digging.
“Their excavations turn over large amounts of soil, helping to retain rainfall and encouraging the growth of new vegetation,” he said.
