In a remarkable conservation success story, efforts to reintroduce bilbies to Mallee Cliffs National Park in far south-west New South Wales are yielding extraordinary results. The breeding trial, initiated in 2019, has seen population numbers explode from just 50 founder animals to an estimated 1,840 bilbies today.
A Century in the Making
The project represents the first attempt to establish a wild bilby population in the Mallee Cliffs habitat in over 100 years. Fifty carefully selected "founder" bilbies were released into a specially designed fenced breeding area in 2019, with 30 of these animals coming from Thistle Island off the coast of South Australia.
Protected Habitat Expansion
Between 2021 and 2023, conservationists successfully transferred 107 bilbies from the initial breeding area into a massive 9,570-hectare fenced, predator-free zone within the national park. The Australian Wildlife Conservancy (AWC), which manages the project in partnership with the New South Wales government, conducted comprehensive surveys revealing the population has now reached 1,840 animals.
"Excluding bilbies from feral cat and fox impacts does really allow them to do well and breed up in numbers and persist in the environment," explained Rachel Ladd, an AWC wildlife ecologist involved in the project.
Monitoring Success
Motion-sensor cameras deployed throughout the protected habitat show the bilbies have dispersed across nearly the entire predator-free zone. "We are picking them up on 95% of our cameras, which alone is a strong indicator that the population has spread across the safe haven and is utilising the full extent of the protected habitat," Ladd reported.
The ecologist noted that project team members had anticipated the possibility of a population boom but described actually witnessing bilbies running through the park and turning over soil as "wonderful."
National Conservation Context
The greater bilby remains listed as vulnerable under Australia's environmental protection laws, currently found in only about 20% of its historical range across the country's arid and semi-arid regions. The Mallee Cliffs initiative represents one of six large predator-free areas managed by the AWC specifically for bilby conservation.
Broader Population Trends
Across properties in New South Wales, South Australia, Western Australia and the Northern Territory, the AWC's annual bilby census revealed even more encouraging trends. Population estimates climbed from approximately 3,300 in 2025 to 5,300 in 2026—more than four times the 2021 estimate of just 1,230 animals.
Notable successes include the Scotia Wildlife Sanctuary in south-west New South Wales, where an estimated 1,830 bilbies now thrive following recovery from severe drought conditions in 2018-19.
Boom and Bust Dynamics
Ladd explained that bilbies naturally experience population fluctuations in response to environmental conditions. "In good times, they are capable of breeding up and increasing their population size relatively rapidly and in dry times their population declines," she noted, adding that while populations may crash during extreme droughts, the animals persist and rebuild when conditions improve.
Ecosystem Engineers at Work
At Newhaven Wildlife Sanctuary on Ngalia Walpiri and Luritja country in the Northern Territory, bilby numbers have surged from 66 founder animals to approximately 530 in just three-and-a-half years, partly due to above-average rainfall.
Ecologist Tim Henderson highlighted the bilbies' role as ecosystem engineers, noting how their foraging and burrowing activities actively reshape landscapes. "Their digging turns over large amounts of soil, helping retain rainfall and promote new vegetation growth," Henderson explained, demonstrating the broader ecological benefits of successful bilby reintroduction programs.
