Community & Business
7 March, 2025
Study provides baseline data for koala populations in our region
A review of the Darling Downs 2024 Koala Population Study was held at the Pittsworth Function Centre on Friday, and revealed three separate koala ‘clusters’ on the Downs identified through DNA testing of scat samples. The results of the study have given a baseline for koala populations in our region and highlighted the outstanding efforts of Pittsworth District Landcare Association (PDLA) volunteers who conducted the sampling.
The study was a community-led project aimed at gaining an understanding of basic population dynamic processes and health of koalas on the Darling Downs, facilitated by OWAD Environment and WildDNA, and funded by an Australian Government grant.
A report on the study was published at the end of 2024 and reviewed on Friday in the presence of key members of the project, namely, Olivia Woosnam and Alex Dudkowski of OWAD Environment, Dr Fiona Hogan, Director of WildDNA laboratory at Federation University in Victoria, PDLA members, Darling Downs Environment Council members, Toowoomba Region Koala Habitat Project co-ordinator Chris Meibusch, community volunteers, and property owners across the Toowoomba Region.
Ms Woosnam said the study has now put koalas in our region on the map, being recognised and taken into account, all the way to a federal government level.
This has been an ongoing project for the PDLA, after receiving the grant in December 2022.
In 2023, PDLA members collected scat samples of wild koalas across the study area from which DNA was isolated and subjected to a range of molecular tests in 2024 to provide insights into the genetic health, disease status and diet of each koala.
Ms Woosnam and Mr Dudkowski trained the PDLA members in this non-invasive genetic sampling process.
A total of 104 samples collected over an eight month period was selected for laboratory Quality Control (‘lab QC’).
While the project aimed for 70 per cent of samples to pass lab QC, the results exceeded expectations with a 94 per cent success rate.
The exceptionally high lab QC results, highlighted the impressive execution by PDLA at collecting quality DNA samples, and the efficacy of this process to successfully achieve significant ‘citizen-science’ results in a timely manner at a fraction of the cost of government or private contractors.
Ninety-one of the 104 samples taken through lab QC provided reliable koala DNA profiles, resulting in an overall DNA profiling success rate of 88 per cent.
This was a massive achievement for all those involved in the project.
Ms Woosnam said such results are often only achieved from invasive methods involving high-quality material such as blood or tissue collected directly from the animals.
DNA profile matching revealed that 91 reliable profiles obtained belong to 81 unique koalas.
All of the DNA profiles tested positive for koala retrovirus (KoRV-A) and 28 per cent tested positive for chlamydia.
The genetic analysis identified three genetic clusters in the Toowoomba area (pictured on page 9):
SEQ-07 - in and immediately south of Toowoomba city;
SEQ-08 in the central parts of the local government area including Pittsworth, Linthorpe, Irongate and Aubigny;
SEQ-09 immediately north of Toowoomba city, including Crows Nest, Goombungee and Highfields.
Dr Hogan said the genetic diversity in the Darling Downs koalas was found to be relatively high with notable variation in allelic richness between the three genetic clusters.
Allelic richness refers to the genetic diversity of a population - a higher allelic richness is associated with well-connected populations that can move and interbreed freely, whereas reduced allelic richness signals habitat fragmentation and isolation.
Although our region showed a lower allelic richness in comparison to other regions, it was still considered high for the species.
Dr Hogan said this was not unexpected as the Pittsworth area and surrounds have been heavily modified since European settlement for agricultural purposes.
Our region was shown to have the highest migration rate with 28 per cent of koalas (per generation) inferred to be migrants from the region north of Toowoomba, and 19 per cent from the City region.
Dr Hogan clarified these results are only a baseline for the information provided and is merely a snapshot in time of when the scats were collected.
She said more funding would be required to “complete the picture”.
The study has proven that non-invasive genetic sampling is both cost-effective and far less stressful to koalas, and the participation and support of landholders and residents was vital to the project’s success.
While our koalas are relatively healthy, their geographic and genetic fragmentation leave Darling Downs koalas highly susceptible to local extinctions.
The full report can be accessed on the Pittsworth Landcare website at www.pittsworthlandcare.org.au
