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Verifying bilby presence and the systematic sampling of wild populations using sign-based protocols – with notes on aerial and ground survey techniques and asserting absence

Southgate, Richard, Dziminski, Martin A., Paltridge, Rachel, Schubert, Andrew, Gaikhorst, Glen
Australian mammalogy 2019 v.41 no.1 pp. 27-38
Macrotis lagotis, aerial surveys, burrows, feces, gait, larvae
The recognition of sign such as tracks, scats, diggings or burrows is widely used to detect rare or elusive species. We describe the type of sign that can be used to confirm the presence of the greater bilby (Macrotis lagotis) in comparison with sign that should be used only to flag potential presence. Clear track imprints of the front and hind feet, diggings at the base of plants to extract root-dwelling larvae, and scats commonly found at diggings can be used individually, or in combination, to verify presence, whereas track gait pattern, diggings in the open, and burrows should be used to flag potential bilby activity but not to verify presence. A protocol to assess potential activity and verify bilby presence is provided. We provide advice on the application of a plot-based technique to systematically search for sign and produce data for the estimation of regional occupancy. Digging and burrow activity can be readily detected from the air but systematic ground-based assessment to determine the rate of false-presence and false-absence needs to accompany aerial survey. The approach to estimate survey effort to assert bilby absence is also described.