Across four nights in the past few months, Taronga's veterinary team from Dubbo and Sydney trapped and conducted health assessments on the bilby population.

Any new animals were identified, microchipped and weighed, and the pouches of the females were checked for signs of breeding

There were 81 individual bilbies assessed, which included 55 that had not been captured before.

Taronga conservation officer Rachael Schildkraut said that information was used to estimate the bilby population at the 110-hectare site to be 136.

"We founded the population in 2019 with just 18 founders so it represents a 650 per cent increase in the total population size which is amazing, particularly given the fact this population has battled drought, it's battled floods," she said.

The bilbies are a semi-wild, free range population. Ms Schildkraut said they essentially like as they would in the wild, having to forrage for themselves to find food and water. It makes them the perfect population for reintroducing into wild conservation areas.

"Because they're essentially living just like a wild population would it means some of the bilbies we trapped last week had never laid eyes on humans before which is pretty special I think," she said.

The greater bilby is nationally listed as vulnerable and is presumed extinct in NSW.

As well as the 136 bilbies at the sanctuary, there have also been two releases of the bilbies into the wild, in areas where they had previously been extinct.

Ms Schildkraut said the population at Taronga Western Plains Zoo would continue to be used as a source population for conservation efforts.

NSW Minister for the Environment Penny Sharpe said reiterated the bilbies were a significant stronghold for the conservation efforts of the species.

"Greater Bilbies bred at Dubbo have been released into Sturt National Park as part of the Wild Deserts program, and the Newhaven Wildlife Sanctuary in central Northern Territory," she said.

"Seeing the population grow is very rewarding for all involved and crucial to bilby conservation efforts in NSW."

She said the NSW government was committed to bringing the bilby population back from the brink.

Reading this on mobile web? Download our news app. It's faster, easier to read and we'll send you alerts for breaking news as it happens.Download in the Apple Store or Google Play.