The population of the greater bilby has significantly increased, with numbers quadrupling in key protected areas over the past five years, the Australian Wildlife Conservancy says its latest data shows.

AWC chief executive officer Tim Allard said bilby populations across six sanctuaries in the Northern Territory, Western Australia, South Australia and New South Wales are estimated at about 5,330 individuals.

“This marks an increase of 2,000 bilbies from last year, when the population was 3,330, and is four times the number recorded in 2021, when only 1,230 were counted,” Mr Allard said.

“This year’s progress at Newhaven Wildlife Sanctuary and Mallee Cliffs National Park highlights significant achievements in Bilby conservation in Australia.

“Seeing populations stabilise, expand, and in some cases boom, gives us real hope. It shows that with the right protection and partnerships, we can turn the tide for threatened wildlife across the country.”

Mr Allard said AWC’s sanctuaries are vital for protecting the world’s largest bilby population, shielding them from threats such as foxes and cats, especially in light of the lesser bilby’s extinction last century.

He said said Newhaven in the NT has seen its bilby population grow to about 530, up from the original 66 founders, due to the sanctuary’s predator-free environment. Mallee Cliffs in New South Wales has reported a rise in its bilby population to 1,840, following the release of 107 bilbies between 2021 and 2023, also in a predator-free area.

“When freed from the relentless predation pressures of feral cats and foxes, Australia’s wildlife can naturally rebuild their populations, often far more rapidly and robustly than expected,” Mr Allard said.

“The bilby population growth at AWC sanctuaries over the last five years shows the remarkable resilience that emerges once key threats are finally removed.”

In 2024, Dr Tim Henderson, a wildlife ecologist with AWC, said the bilby population at Newhaven increased due to favourable environmental conditions, including above-average rainfall of 637mm – the highest since 2001.

Dr Henderson said the presence of numerous bilbies improved Newhaven’s landscape, and he was optimistic about the species’ future with the population expected to continue increasing over the next three to six years.

“Bilbies will breed up successfully when conditions are good and food resources are plentiful,” Dr Henderson said.

“Pair this resource-rich environment with the protection of the feral predator-free fenced area, and the population has been able to thrive.”

At Mallee Cliffs, where spinifex dunes stretch across the landscape, Dr Rachel Ladd said bilbies had rapidly spread throughout the fenced area, using the space for burrowing and breeding.

“Our motion sensor cameras are picking them up across the entire feral predator-free fenced area,” Dr Ladd said.

“We are picking them up on 95 per cent of our cameras, which alone is a strong indicator that the population has spread across the safe haven and utilising the full extent of the protected habitat.”

“Since the bilbies were released into the wider fenced area, we’ve also had reasonable environmental conditions. This would have increased their capacity for high reproductive output, contributing to the steady growth in numbers.”

Dr Henderson said the desert’s boom-and-bust dynamics can lead to fluctuations in population numbers, especially during drier years.

“Nonetheless, the resilience currently observed provides us with significant confidence in the species’ long-term outlook,” Dr Henderson said.

He said bilbies are skilled diggers that positively impact their environment by aerating soil and promoting plant growth through foraging and burrow-building. Their burrows also provide shelter for reintroduced species such as golden bandicoots and brushtail possums, as well as native species including the mulgara.