Thriving koala population near major NSW city could be chlamydia-free

For Daryn McKenny, the Sugarloaf-Stockrington State Conservation Area feels like his backyard.

It was seven years ago that he first spotted a koala in this protected bushland, just a 35-minute drive from Newcastle's CBD.

Since then, Mr McKenny has spent hundreds of hours observing and tracking koalas in the area using discreet, motion-activated trail cameras attached to trees.

The Gamilaraay and Wiradjuri man said walking on country was the key to spotting them.

"I've spent years looking for all the food trees out there, then looking at the messages they give through the tracks and scratchings on them," he said.

"It's about understanding the environment and the ecology from an Aboriginal lens."

A secret population of koalas

Mr McKenny's observations prompted Ryan Witt, a conservation scientist at the University of Newcastle, to study the area.

Since 2020, Dr Witt and his team, including Mr McKenny as Aboriginal lead, have spent more than 250 nights surveying koalas to monitor and track populations across 23,900 hectares.

"We fly thermal-imaging drones up and back, sort of like a lawnmower,"

Dr Witt said.

"We do this across consecutive nights to account for whether a koala is there on a particular night or not."

In late 2025, the research team confirmed 292 koalas in the Sugarloaf-Stockrington area; however, drone surveys and modelling conducted in 2026 have revealed a much larger population.

"We think we have around 2,300 potential koalas in this landscape," Dr Witt said.

"Given the fact that it is an urban population that has somehow survived on the edge of a major city, they seem to be thriving."

Koala population shows no evidence of chlamydia

After noticing an influx of koala joeys on footage throughout 2026, Dr Witt turned his focus to the reproductive health of the Sugarloaf-Stockrington population.

According to Wildlife Health Australia (2023), the number of koalas infected with chlamydia can vary widely between wild populations, from zero to nearly 90 per cent.

To test for the disease, University of Newcastle researchers used drones to locate koalas before collecting fresh scats.

The koala scat, or poo, was preserved on dry ice and transported to specialist laboratories at the University of the Sunshine Coast for genetic and disease testing.

"We found 27 wild koalas without any evidence of chlamydia at the time of testing," Dr Witt said.

"The disease is really prevalent in New South Wales populations, so it's pretty unusual."

A review of wildlife rescue and clinical records from the Lower Hunter region between October 2022 and September 2026 also found no evidence of chlamydia among a further 27 koalas within 30 kilometres of the Sugarloaf-Stockrington State Conservation area.

Dr Witt said while his report's findings were encouraging, they also suggested low genetic diversity among the koalas.

"We think they've been isolated from other populations for some time, which could be why they don't appear to have any disease," he said.

"Monitoring a larger landscape will give us a better understanding of the genetics outside of the core group."

Mark Krockenberger, a specialist veterinary pathologist at the University of Sydney, has studied infectious diseases in koalas for 20 years.

He said only three koala populations in NSW appeared to be chlamydia-free.

"In three years of sampling in southern Sydney, Kanangra-Boyd National Park and Narrandera in the Riverina, no disease was detected," said Professor Krockenberger.

"You can't have 100 per cent say that the pocket near Newcastle is disease-free, but the genetic testing looks promising."

Professor Krockenberger says continued monitoring would give researchers a better picture of koala health in the Sugarloaf-Stockrington area.

"Evidence supports that they are pushing out west of the Pacific Highway, which puts them at risk of contacting other populations with disease," he said.

"This does make it an area worthy of further study and conservation of koalas."

Calls to protect chlamydia-free koala population

Dr Witt has submitted his research to the NSW government for consideration as part of the state's Draft Koala Conservation strategy, which sets out targeted actions to protect koalas and their habitat across the state.

He has recommended increased habitat protection in the Sugarloaf-Stockrington area, installing wildlife exclusion fencing and establishing ongoing, long-term monitoring of this koala population, including longitudinal disease screening.