It’s not just land clearing putting koalas at risk

In 2002, a NSW country town declared itself the Koala Capital of the World. But two decades on, Gunnedah’s koala population has experienced a drastic downturn.

Science, tourism and business are now collaborating in the hope of arresting the rapid decline of the New South Wales town’s once thriving koala population.

Koalas were once a common sight in the town’s streets and villages.

But University of Sydney scientists, who have based their research in the region over the past 20 years, say this special population could be plummeting towards extinction.

“There’s been a lot of work on the genetics of koalas,” behavioural ecologist Dr Valentina Mella says.

“Some populations are special. Gunnedah had a special population. Other populations can be more in-bred. If something catastrophic happens, the population can be wiped out in one go.”

Mella and her USyd colleague, specialist veterinary pathologist Professor Mark Krockenberger, say they have witnessed a rollercoaster ride for Gunnedah koalas, and it’s possible the area could be a microcosm for koalas suffering the effects of climate change and disease across the country.

As part of the Department of Planning and Environment (DPE) NSW Koala Strategy, Mella is studying koalas and climate change. Her research to date has already shown ambient temperature has a significant effect on a koala’s temperature.

“In January 2020, the Gunnedah koalas had the highest temperature (40.8°C) ever documented in a free-ranging koala population,” Mella says.

“Koalas are expected to continue to experience severe contractions in their distribution as the weather becomes warmer and drier due to climate change. Heat stress has been reported as a cause of mortality in koalas across their geographic range but the relationship between temperature and heat stress in koalas across different environmental settings is unclear.

“Climate change is an immediate threat that is already taking its toll on koala populations and therefore an effective forecasting tool to identify upcoming periods of risk and to enable planning for mitigation measures is needed.”

Mella is studying past weather events and historical clinical records with the admission of koalas into care to understand the relationship between heat stress and mortality.

Krockenberger and Mella have also included Gunnedah in recent chlamydia vaccination research. The first trial results will soon be published and Krockenberger is continuing the research in the Sydney region following the drastic drop in koala numbers in Gunnedah.

Gunnedah farmer Rob Frend has hosted USyd researchers at his property where they have seen koala numbers drop from about 75 in 2015, to seven in 2023.

“There has obviously been a massive decline over the last seven or eight years,” Krockenberger says. “The work we have done has shown a big part of that decline is disease – specifically chlamydiosis.

“What’s happened here that has been so remarkable is that the population around this area didn’t have chlamydia until quite recently. What we think we have seen is an epidemic, an outbreak of disease. The population was naive to it and had no defences.

“It is possible there could be a very small pocket of animals that are resistant but at the moment we don’t have any direct evidence of that.”

He says the epidemic has come on the back of drought from 2009-10 and has collided with the more recent 2018-20 drought.

“During that time, not only did a lot of animals die from heat and lack of water, but they were in poor condition and obviously susceptible to disease,” he says. “Climate change has increased heat events and drought events, and koalas are under continued pressure.”

Concern about the dry conditions led to research on the drinking habits of koalas by Rob Frend and Mella. Frend was instrumental in developing an arboreal koala water system known as the “Tree Troff”, designed after he and Mella discovered koalas made use of water provided in containers in trees, not only during the parched summers of the drought but year-round.

“It is very difficult for koalas in drought periods to keep their temperature down,” Mella says. “There were deaths not just from being dehydrated, but the lengths of those periods of heatwaves were just massive. In three weeks, the temperature never went under 29 degrees.

“It is possible there could be a very small pocket of animals that are resistant but at the moment we don’t have any direct evidence of that.”

Professor Mark Krockenberger

“Rob and I started the project to provide water for koalas. Sure, we helped them a bit, but in Gunnedah, disease is really a problem. These animals are so severely affected, they are not doing well. If you add dehydration, it’s just not a good combination.”

The better provision of water and a chlamydia vaccination trial in the region may have come too late to arrest the decline of the Gunnedah koala. Most koalas who contract chlamydia become infertile, and in the past year, researchers have recorded only one joey on Frend’s property.

Krockenberger predicts numbers have yet to reach rock bottom in the region, and the next couple of years could be rough.

But he and Mella remain hopeful the koala will not become extinct in the Koala Capital.

A koala sanctuary and hospital is now being built by Gunnedah Shire Council with more than $12 million in funding through the NSW Government’s Resources for Regions and Regional Communities funds.

“The Gunnedah Koala Sanctuary will include an educational centre and a learning auditorium, a centre for sick and injured koalas and native animals for treatment and rehabilitation and will support koala conservation, providing access for the study of native species,” Gunnedah Shire Mayor Jamie Chaffey says.

More than 5000 gum trees have been planted since 2020 for the purpose of feeding the sanctuary’s inhabitants.

Krockenberger says while there are many challenges ahead for the koala in Gunnedah that a koala sanctuary cannot fix, the centre could be a nice focus for the community to educate people in both the local history of the marsupial and show how to help in its conservation, a belief echoed by Mella.

“There are some excellent examples in New South Wales of koala hospitals that are also attractions,” she says. “This is a good opportunity to talk about what has happened in Gunnedah, and how important it is to research diseases.”

Krockenberger says the sanctuary could be a chance to champion the animal at the local level and attend to sick animals but release back into the wild could prove problematic if the original issues continue to exist.

Krockenberger and Mella are hopeful that continued research around the country will yield results in curbing chlamydia in time to turn the koala’s decline around. When it does, the country – including Gunnedah – must be in good shape for “re-koaling”.

“The habitat here is so great – it’s agricultural land,” Mella says. “It’s really interesting that we pick the land based on fertility, and koalas do the same. They could survive in patches here.

“All the habitat is ready for koalas when they come back.”

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