Study species
Sugar gliders are small (90-150g) gliding possums native to the
Australian mainland but were introduced to Tasmania (Campbell et
al. , 2018). They are omnivores and eat nectar, tree sap and insects but
they also opportunistically eat vertebrate prey (Fleay, 1947, Smith,
1982, Stojanovic et al. , 2014). They are hollow-dependent, often
den in family groups and interchangeably use multiple tree hollows for
denning (Suckling, 1984). Previous estimates of population densities in
continuous forest range from 0.09-0.54 ha- (Gracaninet al. , 2022, Jackson, 2000b, Quin, 1995).
Studies of sugar gliders vary in the methods used and the success
achieved. Monitoring methods for sugar gliders on mainland Australia
have traditionally included live-trapping, nest box surveys and
spotlighting (Jackson, 2000b, Quin, 1995, Smith & Phillips, 1984,
Suckling, 1984, Traill & Lill, 1998). Call playback with conspecific or
owl calls is another method to detect gliders (Alexander, Scotts &
Loyn, 2002, Davey, 1990) and estimate occupancy (Allen et al. ,
2018). Although these methods can indicate sugar glider occupancy or
abundance, they have limitations, especially when population densities
are low. Gracanin et al. (2019) recently introduced the novel
‘selfie-trap’ to identify individual sugar gliders at close-range. Sugar
gliders have unique head stripes, scent glands, tail tip colours, and
often unique ear scars, making unmarked individuals identifiable in
photos. Compared to live-trapping, ‘selfie-traps’ provide a higher
detection probability and more accurate density estimate (Gracaninet al. , 2022).
Sugar gliders are usually surveyed with a standard mammal bait comprised
of peanut butter, honey and oats, in combination with a honey-water lure
sprayed around the trap (Caryl, Thomson & van der Ree, 2013, Knipler,
Dowton & Mikac, 2022, Nowack et al. , 2015, Winning & King,
2007). In Tasmania, this approach has been ineffective even where sugar
gliders are known to be present (Stojanovic et al., 2019). The published
literature contains numerous comparisons of the efficacy of different
survey methods (Davey, 1990, Goldingay & Taylor, 2021, Gracaninet al. , 2022, Vinson, Johnson & Mikac, 2020) and trapping
techniques (Mawbey, 1989, Smith & Phillips, 1984, Winning & King,
2007) for Australian arboreal mammals including various glider species.
However, none have investigated the impact of bait type (herbivore or
predator based) on sugar glider detectability. This is a major gap in
the literature given recent recognition of their widespread predation on
vertebrates (Crates et al. , 2019, Stojanovic et al. , 2018,
Stojanovic et al. , 2014).