Greater gliders, Australia's largest gliding marsupial, are not as adept at gliding as previously believed, according to new research. The first study to measure their aerial ability found they soar an average distance of 19 metres, far shorter than the 100 metres suggested in an 85-year-old study.
Study details and findings
Using infrared binoculars, lasers and tape measures, researchers tracked 41 glides in New South Wales forests. They recorded launch and landing heights, horizontal distance and glide angle, publishing their findings in Australian Mammalogy. The longest flight observed was just under 50 metres.
Lead author Dr Ana Gracanin, a conservation biologist at the Australian National University, said the results challenge long-held assumptions about how far the endangered animals can travel. "The term 'greater' refers to their large body size, rather than the distance they traversed," she explained.
Witnessing the glide
Despite the shorter distances, Gracanin noted that seeing a greater glider in action is still breathtaking. On average, they launch from trees at about 22 metres above ground and land on another tree trunk at about 5 metres. "It goes from being this hunched-over ball of fluff at the top of a tree looking down at you, to suddenly spreading out its limbs and flying over your head like a magical flying carpet," she said.
The gliders use a membrane stretching from their elbows to their ankles to stay aloft. "They get to the top of a tree, launch, spread out their elbows, tuck their paws under their chin and soar through the air," Gracanin added.
Comparison with other gliders
Australia is home to several gliding marsupial species. The yellow-bellied glider is the most aerodynamic, covering 40 metres on average and observed cruising up to 145 metres. In contrast, squirrel gliders typically sail about 12 metres. The 1941 paper that reported 100-metre glides for greater gliders may have been a case of mistaken identity, likely referring to a yellow-bellied glider.
Conservation implications
The findings are significant for conservation, as greater gliders are endangered and depend on continuous tree cover to travel and forage for eucalyptus leaves. Gaps from logging or infrastructure could hinder their movement. Dr Benjamin Wagner, an expert in greater glider habitats at the University of Melbourne, who was not involved in the study, said the results have practical implications. "It means that disturbances to their habitat or habitat loss might be more severe than we thought," Wagner said. In fragmented forests, trees must be closer together than previously assumed for gliders to cross gaps like roads or clearings from fires or timber harvesting.
