Document ID: chunk:federal_register_of_legislation:F2024L00270:body:0:p15
Version: federal_register_of_legislation:F2024L00270
Segment Type: other
Provision Reference: 
Character Range: 40830–43787

distance that responding possums may move to the playback (Harley 2015b) and variability in response rates relating to wind or rain, and to habituation (Lindenmayer et al. 2014a), or seasonal or site-specific variation.
Fixed remote (motion-sensing) cameras, directed at bait stations ('camera traps'), are a cost-effective and efficient survey tool for determining occupancy at a site (Harley et al. 2014). This technique has been shown to have a greater than 85% likelihood of detecting the species where it is present when using three cameras deployed for four weeks (Nelson et al. 2017). Camera traps are now routinely used in surveys by the Department of Energy, Environment and Climate Action (DEECA), Zoos Victoria, Parks Victoria and University of Melbourne. Harley and Eyre (in press) discuss the benefits and limitations of camera trapping surveys for Leadbeater's possum.
The establishment and regular checking of nest boxes has also progressed recently as a survey and monitoring tool, with particular applicability in sub-alpine woodland and lowland swamp forest habitats (Harley 2006b; Harley et al. 2014) and varying success in montane ash forests (Lindenmayer et al. 2003b; Lindenmayer et al. 2009; Harley 2016). The entire lowland population at Yellingbo is provisioned with nest boxes so that den availability does not constrain the subpopulation size (Zoos Victoria unpublished data). In the Central Highlands there are currently more than 750 nest boxes installed for the species, with new designs being developed and tested (Harley 2023). In addition, there are 132 manually excavated chainsaw hollows, of which 62% have been used by Leadbeater's possums as at August 2023 (ARI unpublished).
There have been substantial targeted surveys for Leadbeater's possum in recent years. The number of sites with confirmed records for this species has increased very markedly in recent years, and for many of these the detection rates have been fairly high. These surveys have shown that the species is more widespread than previously recognised and may be more numerous than once thought. However, except where there is recolonisation of the 2009 bushfire area, it is unlikely that the actual number of animals is increasing. While the expanded (known) distribution and higher numbers are encouraging, there is still a declining trend based on habitat condition and trajectory, reflecting the disturbance history of sites.

3.3                 Population size

3.3.1             Estimates of current population size
There is no precise and robust estimate of the total population size for Leadbeater's possum. An exception is for the very small and disjunct subpopulation at Yellingbo, where censuses of all individuals have been undertaken since 1996 (Harley 2015a) – its subpopulation in 2023 was reliably estimated to be 34 individuals (D. Harley pers. comm.).
The TSSC (2019) estimated that the population of possums may have exceeded 10,000