Large numbers of Southern Greater Glider in 2023 burn areas – Strathbogie Forest

Infra-red image of Strathbogie Forest surveys, January-March 2023.

Little was known about the endangered Southern Greater Glider (Petauroides volans) population in this season’s planned burn areas prior to the areas being selected. Only one of the burn areas, Lima East-Mt Albert, had any number of glider records and most of these records came from one small part of this large 500+ ha block. One burn area, Tallangalook-Blacks Ck had not a single Greater Glider record, nor any evidence of surveys (see report for more detail).

Planned burns are carried out with informed knowledge of the impact on plants and animals.This is the lead statement from Forest Fire Management Victoria (FFMV) in “Looking after the environment”, yet FFMV clearly had a very limited understanding of the size and distribution of the Greater Glider population in these burn areas.

How can the risk posed by a planned burn be properly considered if information about species in those areas is wanting? In short, FFMV could not assess the risk to these animals, because they had inadequate data and they chose not to conduct additional surveys to improve that understanding. Risk management begins with risk assessment – it’s not rocket science.

So, it was left up to community groups to do the work (again!) – to improve the level of knowledge about the Greater Glider population in the planned burn areas. During January and February 2023 SOSF surveyed 13 transects across four of the planned burn areas. The transects were predominantly in Herb-rich Foothill Forest, but included small areas of Grassy Dry Forest, Riparian Forest Mosaic and Damp Forest.

Before outlining the survey results, here’s a short video of several of the Southern Greater Gliders we saw on the surveys. The video is low-res and most clips were taken 30 to 50 m from the subject (hence the shaky, blurry image). In the video you’ll see the black and the less common grey colour phase (including one glider that is almost totally black, even ventrally); two juveniles/sub-adults (smaller body size and noticeably shorter tails); a grey-phas glider feeding on red stringybark (Eucalyptus macrorhyncha) flowers and buds; most gliders sitting motionless (as usual), or climbing using an almost feline gait.

The surveys were conducted along 7.3 km of forest road. Survey technique relied on traditional white light detection of greater Gliders, supplemented with infra-red detection for smaller and cryptic species.

We detected 105 individual Greater Gliders, a mean detection rate of 14 gliders per kilometer. Detection rates per transect varied from 6 to 24 Greater Glider/km with 10 of the 13 transects having rates greater than 10 Greater Glider/km. Transects with the lowest detection rates (# 6, 8 & 9) were in drier sites lacking large habitat trees. These sites included the trees species Broad-leaved Peppermint (Eucalyptus dives), Red Stringybark (E. macrorhyncha) and Long-leaved Box (E. goniocalyx), indicative of lower quality Greater Glider habitat. Parts of Strathbogie South-Ruoaks Rd burn area recorded the lowest detection rates. This area has suffered considerably more from disturbance (logging and fire) and contains far fewer, large hollow-bearing trees than the other burn areas.

Greater Glider was detected almost four times as often as the next most numerous species, the Common or Eastern Ringtail Possum (Pseudocheirus peregrinus). None of the other species were detected more than a handful of times. The use of thermal imaging, whilst not particularly influential in detecting the Greater Glider, did assist in detecting both Krefft’s Glider (Petaurus notatus) and Feathertail Glider (Acrobates sp.).

Several observations made during the survey are noteworthy:

  • Greater Gliders were observed feeding on foliage in Long-leaved Box trees (transect #3) and on foliage and blossom in Red Stringybark (#6).
  • A surprisingly small number of Mountain Brushtail Possums (Trichosurus cuninghami) were detected – only three individuals in the 7.3 km of transect.
  • The correlation between the presence of large trees (e.g. >1 m dbh) in the forest, particularly gums (Victorian Blue, Manna, Mountain), and presence and frequency of detection of Greater Gliders was very strong. Even in obviously degraded forest (logged and burnt) with few large trees, the occasional occurrence of a large gum was usually accompanied by a Greater Glider detection. The highest detection rates occurred where there were many large, old gums. This emphasizes that suitable tree hollows are a limiting factor for Greater Glider populations in this forest.

With detection rates like these, it’s no wonder that in 2019 the Victorian Government designated the Strathbogie State Forest an Immediate Protection Area for the Southern Greater Glider (Petauroides volans). Too-frequent fire, such as planned burning, is a known risk to the Greater Glider (EPBC Advice, FFG Action Statement) and should be front of mind for relevant land managers.

Save Our Strathbogie Forest has called for the government to cancel this year’s proposed burns, until a less destructive burning regime is developed.

A Krefft’s Glider (Petaurus notatus) at a feeding incision in Silver Wattle (Acacia dealbata) in Strathbogie South-Ruoaks Rd burn block.

One response to “Large numbers of Southern Greater Glider in 2023 burn areas – Strathbogie Forest

  1. Donna Robertson

    Back Burn more securely and harmless to our native animals plants 🌳 trees

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