Monitoring population trends are essential for the conservation of threatened species, and establishing best‐practice methods improves the efficiency, accuracy and long‐term value of data collected. For the nationally endangered Prodontria lewisii (Cromwell chafer beetle), monitoring has typically included soil core sampling for larvae, and pitfall trapping or nighttime quadrat surveys for adult beetles. However, these approaches often yield low capture rates and/or limited comparability between years. We tested whether adding drift barriers or bait (canned pear) to pitfall traps would increase adult beetle captures. Drift barriers increased captures by 29% across two seasons, whereas bait had no effect. A preliminary assessment also indicated that trail cameras can detect P. lewisii , although capture rates were low, and further testing—particularly earlier in the season—is required to determine their efficacy. Overall, pitfall traps fitted with drift barriers provide a more reliable monitoring method for P. lewisii than unmodified pitfalls. If applied consistently within the Cromwell Chafer Beetle Nature Reserve each year, this approach has the potential to generate robust long‐term population trend data, but substantial work is still required to develop an appropriate sampling design. Given other known limitations of pitfall traps, we recommend drift barriers and different baits are also investigated for use in combination with trail cameras as an alternative monitoring tool, and that other novel monitoring technologies are investigated.
Williams et al. (Sun,) studied this question.