A test of the feasibility of using glue traps to sample the invertebrate fauna in bilby Macrotis lagotis foraging pits

Interactions between mammals and invertebrates remain a gap in our knowledge of the role of fossorial foragers in Australian ecosystems. This is probably because digging mammals disappeared from the majority of their former range before they could be studied and because of the difficulties associated with sampling invertebrates in foraging pits. Bilbies were reintroduced into a rangeland restoration program in Western Australia, providing an opportunity to compare invertebrates in their foraging pits with the undisturbed surface soil. The challenge was to develop a method for collecting invertebrates while minimising disturbance of the floor of the foraging pits. This study investigated the feasibility of using folding cardboard glue traps to sample the invertebrates. The traps proved to be easy to deploy and collect and concerns that the traps on the soil surface would collect more soil than those in the foraging pits, thereby biasing the invertebrate sample, were not realised. No firm conclusions can be made about the interactions between bilby foraging and invertebrates from this short term study. However, there were indications that the abundance and composition of ant fauna may differ between foraging pits and the soil surface. Calculations were made to determine how many traps would have to be deployed to collect the representative sample needed to make valid statistical comparisons.