Narrandera’s koala colony, which has now grown to more than 290 over 1600 hectares, is being studied as part of the $190 million NSW Koala Strategy as a model for how to re-establish populations.

Twenty-three koalas were originally introduced to the reserve near Narrandera in the 1970s, the first official translocation of koalas for conservation in the state.

Andrew Baker from the National Parks and Wildlife Service (NPWS) says DNA testing has revealed the Narrandera koalas are the most genetically diverse in southern NSW with genetic links to populations in Victoria, northern NSW, and southern Queensland.

The koalas are described as very healthy and chlamydia-free – chlamydia is a highly infectious bacterial disease that can make koalas more vulnerable to death from other causes.

NPWS is working with the Murrumbidgee Landcare Network and Riverina Local Land Services to fill in knowledge gaps about the size of the population and just how far along the river the koalas have spread.

Drones with thermal cameras have been used to count the koalas and sound recorders are being installed in national parks, and on Crown land and farms along a 100-kilometre stretch of the river.

Mr Baker said the recorders were an efficient way of recording the koala mating calls from dawn until dusk.

The acoustic monitors are installed for 14 days to record koala calls.

“They’re easy to deploy, you can cover a large area in a short period of time and so we’re using those in the outlying areas to find out if there are koalas,” he said.

“We put the data through a computer and it takes hours and hours and hours of recording and just chops out the little snippets where it thinks there’s a koala — then those little snippets get manually verified.”

At Berrembed Station, 20km upstream from Narrandera, manager Tony McManus said koalas were a welcome part of the scenery. In the past six months he has seen six or more koalas.

Mr McManus said the billabongs and red gum forests provided important wildlife habitat, alongside cropping and livestock operations.

Murrumbidgee Landcare project officer Leigh Mathieson of Narrandera said understanding where the koalas had moved would help efforts to maintain and improve habitat.

“We can then look at things that may be hindering the koalas from actually moving beyond their current population,” he said.

“It allows us to understand where there is healthy remnant vegetation and tailor those little projects to areas that just need that little bit more vegetation.”

With so much of the river corridor owned by farmers, Mr Mathieson was encouraged by the interest in the project.

“It’s an amazing thing to see the buy-in from everybody,” he said.

Narrandera has a very special koala population – the descendants of the first ever translocation of koalas in NSW in the early 1970s when about 20 koalas were released at Murrumbidgee Valley Nature Reserve on Wiradjuri Country to re-establish the extinct colony. These koalas came from a few of areas to promote genetic diversity, including Northern NSW and French Island in Victoria.

Fast forward 50 years, and the koala team are still researching and monitoring this koala population. Using drones and audio detection devices, almost 300 koalas were detected in Narrandera, and their distinctive calls have been picked up far and wide along the Murrumbidgee River.

Some of the koalas were carefully captured and released to assess their health and collect DNA samples. All Narrandera koalas captured in 2022 were chlamydia free and also showed low levels of inbreeding, with a higher genetic diversity than other groups in southern NSW. The bloodlines from their Victorian and Northern NSW ancestors are still present.

The Narrandera conservation effort is an important example of how conservation translocations, as part of a suite of measures, can help this iconic animal survive in the wild.

This article appeared in the Narrandera Argus, 7 December 2023.