In the dead of night on the dark and often misty mountain peaks of far-north Queensland, researchers and rangers search for possum species that are disappearing from their natural habitat.
Climate change is driving them from parts of their mountain homes.
Among them is one of Queensland’s most recognisable animals — the Herbert River ringtail possum, the logo of the state’s Parks and Wildlife Service worn on the uniforms of its rangers.
At 600 metres above sea level, the edge of the possums’ natural range, researchers are making stark discoveries.
“Right now, we just don’t see any; in certain locations we haven’t seen a single individual for a decade,” said James Cook University (JCU) PhD student Alejandro de la Fuente.
“The possums that are dying are not being replaced by newborns, and that basically leads to a long-term decline in the net number of ringtail possums in that location.”
‘Islands in the landscape’
JCU professor Stephen Williams has been researching and monitoring the effects of climate change on mountain ecosystems for more than 20 years.
“As the summers get hotter and hotter, it’s essentially pushing [the possums] up the mountain, and at the lower elevations the heat’s getting too much for them and they’ve disappeared,” he said.
“Unfortunately, the predictions we made about climate change almost 20 years ago are now coming true.”
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Researchers have joined forces with Queensland Parks and Wildlife Service (QPWS) rangers and the Wet Tropics Management Authority (WTMA) to monitor populations of the Herbert River ringtail and other high-altitude species suffering the impact of a warming climate.
Roger James, ranger in charge of the QPWS Tinaroo base, said lemuroid and green ringtail possums faced the same dire situation as their not-so-distant cousin.
“The problem is these mountain peaks are like islands in the landscape,” he said.
“When you’re at the top of the mountain there are no other mountain tops around, so if you want to go to another mountain peak you have to go down and across the farmlands and the possums just don’t do that.
“They’re stuck on these islands on these mountain tops, and that’s the critical thing.”
‘Nowhere else to go’
QPWS natural resource management ranger Ben Solowiej said rangers’ presence in Queensland’s national parks put them in a valuable position to contribute to monitoring the state’s endemic species.
“We have the ability to provide staff to undertake the surveys and provide the logistical support,” he said.
“In the past 18 months, taking out the wet season which would be about six months of that, we’ve managed to contribute over 110 survey nights, whereas in the past that might have taken years to achieve.”
While the concentration of possums at elevations higher than 1,000 metres above sea level is increasing, there is no cause for celebration.
As the climate warms, researchers fear the possums will continue to disappear.
“After the mountain tops, they have literally nowhere else to go up in elevation, and it’s really difficult to do conservation in an area that’s already protected,” Mr de la Fuente said.
Well-protected animals disappearing
The teams monitoring the possums are finding no shortage of other Wet Tropics species suffering a similar fate.
Mr James and his fellow rangers at Tinaroo are witnessing the disappearance of mammals, birds, reptiles and invertebrates that usually inhabit the mountain peaks.
“The golden bowerbird, an iconic bird species for the Wet Tropics, is being monitored because, if the effects of climate change are going to pan out as predicted, it’s likely to be one of the first endemic species to disappear off the top of the mountain,” Mr James said.
“The spotted-tail quoll population on the Lamb Range is down to just a handful of individuals.”
Professor Williams said the disappearance of endemic species from World Heritage-protected areas was testament to the impact of climate change.
“It’s really critical right now as we’ve already seen a 50-per-cent decline in the total population of some species,” he said.
“All of these species that we would have considered to be completely safe because they’re in a well-protected, well-managed World Heritage area are disappearing in front of our eyes.”