Bilby boom: breeding trial to reintroduce species to Mallee Cliffs national park shows signs of success | Conservation
Efforts to reintroduce bilbies to south-western New South Wales are showing signs of success; Seven years after the first breeding attempt in Mallee Cliffs national park, the number has risen to almost 2,000.
Fifty “founding” bilbies, including 30 from Thistle Island off the coast of South Australia, were released into a fenced breeding area in 2019 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 the park’s 9,570 hectares of fenced, predator-free habitat. The Australian Wildlife Conservancy (AWC), which manages the conservation project with the state government, has carried out initial surveys and estimates the total population now stands at 1,840 bilbies.
“Excluding bilbies from feral cat and fox impacts allows them to do really well, reproduce in numbers and persist in the environment,” said AWC wildlife ecologist Rachel Ladd.
He said the project team “absolutely knew” a population explosion was possible and that it was “wonderful” to see bilbies running around the park and turning over the soil.
Ladd said motion-sensor cameras showed the animals had dispersed across the larger fenced area and had dug enough burrows to occupy much of the predator-free habitat.
“We are detecting 95 percent of our cameras, which alone is a strong indication that the population has spread into the safe zone. [is] “Using the entire protected habitat,” he said.
The greater bilby is listed as vulnerable under Australia’s natural laws and is found in only 20% of its former range in the country’s arid and semi-arid regions.
The Mallee Cliffs project is one of six major predator-free zones managed by the AWC.
The organization’s annual bilby census found numbers on properties in NSW, South Australia, Western Australia and the Northern Territory increased from an estimated 3,300 in 2025 to 5,300 in 2026. The result is more than four times the population estimate in 2021 (1,230).
This includes an estimated 1,830 bilbies in the Scotia Wildlife Sanctuary in south-western NSW, where the population has been steadily recovering following the severe drought of 2018-19.
While the nature of drylands makes bilbies a rapidly evolving and disappearing species, census results reflect better environmental conditions for breeding, Ladd said. Population numbers are expected to fluctuate, he said.
“In good times they have the capacity to reproduce and increase their population size relatively quickly, while in dry times their populations decline,” he said.
“Collapses may occur depending on how dry the air is, but they persist and increase their numbers again.”
Research at Newhaven Wildlife Sanctuary in Ngalia Walpiri and Luritja country in the NT showed a rapid increase in numbers from 66 founder bilbies three-and-a-half years ago to an estimated 530, driven in part by above-average rainfall. Ecologist Tim Henderson said bilbies, known as ecosystem engineers, were reshaping the landscape in Newhaven as they foraged and nested.
“Their excavation reveals large amounts of soil, helps retain rainfall and encourages the growth of new vegetation,” he said.
