The future of Australia's largest gliding marsupial is on the line as an argument over semantics plays out in a NSW court.
The Forestry Corporation of NSW spent a day in court this week, defending how it looks for trees that provide food, shelter and breeding hollows for three threatened and vulnerable glider species.
These include the greater glider, known for its death-defying treetop leaps, which was listed as threatened even before the Black Summer bushfires wiped out over a third of its habitat in 2019-20.
The species has since been up-listed to endangered, meaning it's at very high risk of becoming extinct in the wild in the near future.
Despite that, the state-owned corporation continues to log native forests where unburnt chunks of habitat remain.
In recent months the NSW environmental watchdog has placed stop-work orders on the corporation, alleging it failed to competently look for glider den trees in two forests before logging began.
In the Tallaganda State Forest, for example, the corporation found just one den tree in a logging compartment.
The Environment Protection Authority later found 20, and citizen scientists who conducted their own den tree surveys reported similar alleged failings.
Now a conservation group has taken the corporation to the NSW Land and Environment Court, seeking a temporary halt to timber harvesting in parts of other forests until "adequate" den tree surveys are done.
Barristers for the Forestry Corporation and South East Forest Rescue went head to head in court on Tuesday, offering competing interpretations of what constitutes a den tree.
At the heart of the case are nine little words - the final phrase of a definition in the Coastal Integrated Forestry Operations Approval (CIFOA), the legal framework that governs logging in state forests.
It defines a glider den tree as one "that includes, but is not limited to, a tree-hollow or other hole, crevice or fissure in a tree, which the subject species is seen entering or leaving".
Forestry Corporation says it has to carry out habitat searches before logging starts, but as far as it's concerned a tree is only a den tree if a glider is seen coming or going.
South East Forest Rescue has a different interpretation, insisting "the ordinary reading of den is relied upon" and the part that mentions glider sightings is merely an example.
The conservation group's barrister Jonathan Korman told the court there would be dangerous outcomes if the Forestry Corporation's position prevails.
"Forestry Corporation says ... if you haven't seen a glider entering or exiting, there is no den tree," he told Justice Sarah Pritchard.
"And that means if you cut down trees in the vicinity of gliders - you don't leave a single one - you haven't actually cut down a den tree."
Mr Korman urged the court to weigh in and make a choice between the definitions.
The Forestry Corporation's barrister Ian Hemmings SC told the court his client was working to the existing CIFOA requirements.
But he said the framework made it "abundantly clear that it's not a counsel of perfection - that that which we are required to do may not find den trees".
In written evidence for South East Forest Rescue, Curtin University associate professor Grant Wardell-Johnson said it was possible to identify all den trees used by gliders in a logging zone.
But he said it would require a range of methods and significant resources, given gliders are constantly moving between den trees, with each using up to 20 over several hectares of forest.
The veteran ecologist warned there was "a real threat of serious and irreversible damage" to the greater glider and its environment from logging as it's currently done.
But Mr Hemmings said it was "unnecessary" to engage with the expert's evidence.
"It is suggested we are in breach (of the CIFOA) because we are not carrying out the investigation as the associate professor says.
"The associate professor says we need to find every tree, and inspect each physical feature for the current or past occupation of a glider.
"Nowhere will a court find anything remotely similar to that obligation under the CIFOA."
Mr Hemmings told the court consultations were under way between Forestry Corporation and the EPA in relation to the stop-work orders that halted logging in the Tallaganda and Flat Rock state forests.
He said discussions were focused on whether the watchdog was satisfied with the broad area habitat searches carried out in those locations.
He noted that if the EPA was unhappy with the current regulations, it had the power to change them at any stage.
"That includes ... the definitions."
The EPA is not a party to the court case brought by South East Forest Rescue.
It has previously said it's revising protocols to ensure habitat searches are competently conducted. No details have yet been released about potential changes.
Justice Pritchard reserved her judgment and is expected by rule by the middle of next week on whether South East Forest Rescue has the legal standing to bring enforcement action against the Forestry Corporation.
In the interim, the Forestry Corporation has extended a voluntary undertaking not to log in some of the compartments the conservation group has identified as prime glider habitat.
