Rules designed to protect one of Australia’s most elusive tree-climbing species could actually be leaving it stressed and undernourished, new evidence suggests. Greater gliders are listed as critically endangered because most of the tree hollows they rely on to survive have been destroyed.
Forestry Corporation of NSW, a business owned and supported by the government, oversees the harvesting of native forest across state forests, including around the last remnants of greater glider habitat.
Under controversial regulations designed by the Environment Protection Authority (EPA), a buffer zone needs to be left around trees identified as greater glider homes. That means when one is spotted on a branch, trees are protected for 25 metres around the tree, and when a hollow is discovered that expands to 50 metres.
But what an independently reviewed GPS study has discovered is that greater gliders have an average territory of 2.06 hectares which equates to a buffer of approximately 80 square metres. Published in the journal Biological Conservation, the research found that even when the habitat was severely burned by bushfires, the gliders would stay put and refuse to expand their territory.
The NSW Government is committed to logging some of the greater glider’s last remaining habitat at Tallaganda State Forest. Source: Kailas Wild/Andrew Kaineder
How do greater gliders cope when their territory is reduced?
To cope with the lack of food left after bushfires, gliders would increase their movements within their established range to collect the food they needed. This is detrimental to gliders because they need to keep still for long periods of time to digest and conserve energy and remain in optimum condition.
This is because the food they eat provides little nutrition — a difficult circumstance for such a large animal. They grow to over 1 metre in length when you combine their bodies (35-45 cm) and tails (45-60 cm), and weigh between 90 grams and 1.7 kg.
Lead author, University of Sydney PhD candidate Vivianna Miritis, told Yahoo News the gliders were “coping” with disturbance, but prolonged periods with not enough habitat would ultimately lead them to “stress”. And this isn’t ideal for a species that needs to recover from being listed as endangered.
With some of the buffer zones, three times less than the average territory, they’ve been described as “hugely inadequate” by World Wide Fund for Nature-Australia ecologist Dr Kita Ashman.
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The research was undertaken in Tallaganda State Forest, which was partially logged this year by Forestry Corporation. Ashman argues its forests like these with habitat that survived the 2019/2020 Black Summer bushfires that need to be protected.
A separate concern with the buffer zones is that each one is separated from the rest of the forest when the surrounding trees are cleared. “We get this Swiss cheese effect where there are all these tiny pockets that can’t provide adequate habitat,” she said.
Buffer zones around den trees are just 50 metres, but greater glider ranges are an average of 80 metres. Source: Dr Kita Ashman/WWF-Australia
Will anything change when it comes to protecting greater gliders?
The EPA did not respond directly to Yahoo’s questions about whether the new research would result in changes to its greater glider buffer zone regulations. But it noted it does have the power to make changes to forestry protocols.
Instead, it issued a statement about its existing greater glider protections, which it claimed were created after consideration of academic research, conservation advice and engagement with experts in the field.
“Earlier this year, we issued a site-specific biodiversity condition under the Coastal Integrated Forestry Operation Approvals (CIFOA), enhancing protections for southern greater gliders,” it said.
“These measures reflect the species’ recent endangered status and their unique habitat needs. The new tree retention requirements and temporary buffer zones around trees where greater gliders are sighted during nocturnal surveys increase protections within critical greater glider habitats”
Forestry Corporation of NSW has been in the spotlight this year after it revealed its native forest logging had run at an annual loss of $29 million. Asked about greater glider protection requirements, it noted they are set by the EPA.
“In the 2023-24 year more than 285,000 individual habitat trees were marked and protected as koala feed trees, hollow bearing trees, giant trees, dead standing trees, nectar trees, glossy black trees and glider trees,” it said. “For each tree identified and protected, on average 30 others also remain to grow into future sawlogs or hollow bearing trees.”
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