As part of our Strathbogie Forest Citizen Science Project, in the last year or so, we conducted 42 hours of spotlighting, along 27 km of forest tracks, surveying approximately 161 ha of forest. Most of these community surveys occurred in April and May 2017 and ran twice per week – Monday and Friday evenings. Twenty-five different people took part in the spotlighting surveys. All fauna detected during the surveys were recorded, but the focus was on three species- Greater Glider (Petauroides volans), Yellow-bellied Glider (Petaurus australis) and Powerful Owl (Ninox strenua).
During these surveys, Greater Gliders were detected 202 times, Common Ringtail Possums 46 times, Koalas 27, Mountain Brushtail Possums 16 and Sugar Gliders three times. There were no detections of Yellow-bellied Glider. We detected Southern Boobook Owls on 10 occasions, Powerful Owls four times and Tawny Frogmouth and Owlet Nightjar once each.
Update: Victorian government surveys have confirmed that the Strathbogie Forest contains the highest detection rates of Greater Gliders recorded anywhere in Victoria, possibly Australia. And those forests are about to be logged!
There are no special protections for Greater Gliders in the Strathbogie State Forest, nor in any other state forest in north-east Victoria. On several of our survey transects, the detection rate of Greater Gliders was well above 10 animals/km, enough to warrant protections of 100 ha of forest at each site in other parts of Victoria, but not here in the Strathbogies.
The highest detection rate for Greater Gliders in our surveys (transects >300 m long) was 16.3 animals/km, with nine surveys having detection rates equivalent to 10 animals/km or higher. Across all surveys, regardless of where they were done, the average number of Greater Glider detections was 7.5 animals per kilometer transect. Considering that this includes transects that had detection rates as low as 1.2 animals/km, this is a remarkably high rate – the Strathbogie State Forest is truly a hotspot for Greater Gliders!
It’s great news for this threatened species and the forest, but it’s not necessarily all rosy. The population of Greater Gliders in the Strathbogie Ranges is completely isolated from those to the east and south, in the main part of the Great Dividing Range – it’s an island population. And of course the stronghold, the core habitat, the highest priority habitat for Greater Gliders, is the wetter, higher altitude forests of the eastern Strathbogie Ranges – the Strathbogie State Forest. This is precisely that part of the forest targeted for logging over the next few seasons.
Survey transects that had low detection rates were in forests that are young and have few big, old trees (eg >1m dbh). Lack of big trees is a direct consequence of logging and repeated fuel reduction burns.
The Powerful Owl has a loud, distinctive call. Powerful Owls were detected on four occasions during the surveys, in two separate locations. Together with another detection we made in 2014, these five records are the only documented Powerful Owl records in the state forest in the last 15+ years.
In spite of being the most vocal and active of all the marsupial gliders, this species was not detected at all during the surveys. While perhaps not surprising, this was a very disappointing result. The presence of Yellow-bellied Gliders in the Strathbogie Ranges was first documented in 1996, on two separate occasions and at the one location near Mt Barranhet on the western margins of the state forest. Despite visits to the same site and surrounds in subsequent years, the species has not been detected again – by us or anyone else; there are no records of Yellow-bellied Gliders on any of the state-wide fauna databases, other than those from 1994.
We had hoped that the extensive surveys conducted during this survey might detect Yellow-bellied Gliders elsewhere in the forest. The failure to do so adds more weight to the devastating prospect that this species is now extinct in the Strathbogie forest.
The surveys were conducted by ecologists Bertram Lobert and Lance Williams. All fauna records have been submitted to the Victorian Biodiversity Atlas. Sincere thanks to all the volunteers that helped with the surveys.
This is a Strathbogie Ranges CMN project. This project was funded with the support of the Victorian Government.