Context . An understanding of population size and status is necessary for the implementation of appropriate conservation measures to recover threatened taxa. Mark–recapture studies at large spatial scales are impractical and expensive and a rapid survey technique is an attractive option to provide a measure of relative abundance for cryptic species, using indicators of activity.
Aims . The aim of our study was to use conventional methods for population estimation to calibrate a rapid survey technique for the quokka (Setonix brachyurus) in the southern forests of Western Australia, with a view to providing quantitative outcomes from this widely adopted monitoring approach.
Methods . We evaluated the accuracy of relative abundances obtained from the rapid survey technique by comparing them with abundance estimates obtained through established methods for the estimation of populations, including web-based mark–recapture and transect-based counts of activity indicators and sightings.
Key results . The rapid survey technique was effective at determining presence of quokkas but resulted in an over-estimation of population size because of inaccurate assumptions about occupancy and relative abundance of animals. An alternative survey method based on counts of fresh faecal-pellet groups was found to provide a more reliable and practical estimation of population abundance (R2 = 0.97).
Conclusions . Activity indices can be used to quantify population abundance, but only for indicators of activity that can be detected readily and for which freshness of activity can be determined.
Implications . Our findings suggest that a rapid survey based on activity indices can be used to evaluate quantitatively the population size of a species that is rare and potentially mobile at a landscape scale. The attraction of these techniques is that they provide a rapid and inexpensive survey option that is potentially applicable to any cryptic and/or threatened species and is practical for resource-constrained land managers.
