This article is more than 11 months old

This article is more than 11 months old

Bilbies have been reintroduced to the Mallee Cliffs national park in the far south-west of New South Wales in an effort to restore populations of the marsupial, which is regionally extinct in the state.

Greater bilbies haven’t been seen in the national park for more than a century.

Last week, 30 that had been relocated from Thistle Island, off the coast of South Australia, were released into the park, protected by a predator-free enclosure that is the largest of its kind in the southern hemisphere.

The 37.2km purpose-built fence has created an area of 9,570 hectares that will be cleared of predators such as feral cats and foxes that are a major threat to bilbies.

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The newly released animals are currently in a smaller area of 480 hectares while trappers remove predators from the main area. Once that work is complete it will be monitored for several months before it is declared feral-free.

The predator-proof enclosure has been established by the Australian Wildlife Conservancy (AWC), in partnership with the NSW government.

It is part of a larger project that will also see another nine regionally extinct species reintroduced to the national park.

Facebook Twitter Pinterest Feral predator-proof fence built in Mallee Cliffs national park. Photograph: Wayne Lawler/AWC

They include the western quoll, the numbat, the western barred bandicoot, the bridled nailtail wallaby, and the greater stick-nest rat.

Laurence Berry, a wildlife ecologist with the AWC, said seven of the species would be released into the park in 2020.

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He said bilbies used to occur across 70% of the Australian mainland but they are now found in just 20% of their former range.

Berry said the purpose of the enclosure was to try to boost the population of the species in both the short and longer term.

“In the short term, it helps to just safeguard the species by establishing a population,” he said.

“In the long term, it’s about creating a new population that’s genetically different to the existing populations that gives them resilience into the long term.”

He said projects like predator-free fences were being used because longer-term solutions to eradicate feral animals were still being developed.

Berry said the enclosure covered a huge area and, while it was still very early days, the bilbies seemed to be adjusting well to their new environment.

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“They’re already digging burrows, there’s evidence of digging on the ground, and they’re foraging,” he said.

The NSW environment minister, Matt Kean, said the project was aimed at “turning around the extinction rates for our native animals”.

“Bilbies are a loved and iconic Australian animal that has been extinct in the wild in NSW for over 100 years. We have an opportunity to bring them back to NSW national parks by using special fenced-off areas and it’s important we do this,” he said.

Australia has the highest rate of mammal extinction in the world, which has been driven not only by threats such as predation by feral pests, but also large amounts of habitat loss.

A federal Senate inquiry is currently examining Australia’s high rates of fauna extinction. An interim report by the committee, produced before the May election, called for an overhaul of Australia’s environment law – the Environment Protection and Biodiversity Conservation Act.

A statutory review of the EPBC Act, which is undertaken every 10 years, is due to commence this month.