Thermal drone surveys in the Wombeyan Karst Conservation Reserve have uncovered a glut of 50 endangered southern greater gliders in just one night.

Drone pilot and ecologist Adrian Sujaraj studied areas previously monitored by ecologists, focusing on confirming evidence of tree-dwelling mammals, particularly southern greater gliders.

“The thermal drones are incredibly effective,” said Sujaraj.

“Previously, when searching for these arboreal animals, they were quite cryptic and difficult to find. Thermal imaging technology provides a unique advantage. Every mammal emits a heat signature, and by flying above the canopy, we can effectively detect and locate all the animals within the survey area.

“Whenever a heat signature was detected, we switched the drone to colour imagery and used a spotlight to identify the species. We successfully located approximately 50 greater gliders across 50 hectares,” he says.

“Drones are an exciting addition to the set of tools ecologists have to survey cryptic wildlife, but they are still limited. Drones in conjunction with other existing methods like acoustic detection and historical data could go a long way towards mapping the distributions of mammals that have typically been difficult to survey for,” Sujaraj says.

The surveys were commissioned by K2W Link as part of Cores, Corridors and Koalas – a partnership between the Great Eastern Ranges (GER) and WWF-Australia to restore and connect critical habitat for forest-dependent native animals.

“To find that many is exciting, it’s amazing. It shows that greater gliders can thrive when they have undisturbed habitat. So often that’s not the case,” said Dr Kita Ashman, a conservation scientist with the World Wide Fund for Nature-Australia.

In fact, populations have crashed by as much as 80% in the last 20 years due to habitat destruction including land-clearing and logging, as well as droughts and bushfires fuelled by a rapidly changing climate.

The drone surveys, combined with traditional spotlight searches, have provided valuable insights and highlighted the effectiveness of conservation efforts to support the endangered marsupial by K2W and other local groups.

Building on the evidence

Since 2015, experienced ecologists Peter and Judy Smith have been studying arboreal mammals in the Blue Mountains National Park and further south in the Southern Tablelands at Mares Forest National Park and Wombeyan Karst Conservation Reserve.

At these locations, wildlife suffered heatwaves and drought followed by the 2019-20 mega fires.

By conducting spotlight surveys in the same sections of forest, the Smiths have recorded the impact of these extreme events – worsened by climate change – on greater gliders.

They’ve shown that well-managed, high-quality habitat significantly improves the survival of greater gliders and other native wildlife.

“Recovery has been particularly strong in lightly burnt and unburnt transects, which were the tallest forests and the best habitat for greater gliders prior to the fires,” Peter Smith said.

“High rainfall and good eucalypt growth since the fires have led to an increase in glider numbers. There are now more gliders on these transects than there were prior to the 2019 drought.

 

But it’s a different story in transects through severely burnt forest, where greater gliders were eradicated by the fires and have shown no signs of recovery.

“In the immediate aftermath of the fires, there was no live eucalypt foliage for the gliders to feed on and they disappeared from these areas. We have not seen the species in any of our post-fire surveys of severely burnt forest over the last five years.

Peter Smith emphasised the critical need to reduce the incidence and extent of high to extreme-severity fires.

“Notably, the increase has been significant on unburnt and low-severity-burned transects, particularly those with the tallest forests and the best greater glider habitat. These tall Brown Barrel, Ribbon Gum, and Narrow-leaved Peppermint forests in Mares Forest NP and the southern end of Blue Mountains NP now support exceptional numbers of greater gliders and are vital for the species’ recovery in this region,” he said.

Through Cores, Corridors and Koalas, WWF-Australia, GER and local partners continue to work to ensure the recovery and persistence of greater gliders in the K2W Link and beyond.