Temporal Pass Plots: An intuitive method for visualising activity patterns of bats and other vocalising animals

Abstract

Abstract Bats perform a number of ecosystem services but face numerous threats. Improved monitoring strategies are essential to better target conservation efforts, and passive acoustic monitoring (PAM) is being increasingly used to record bat activity. Although temporal patterns of bat activity can provide useful information about behaviour and habitat use, such assessments are rarely performed. Here, we describe the Temporal Pass Plot (TPP) that utilises audio file metadata to create highly detailed visualisations of bat activity, enabling direct comparisons of temporal activity patterns between different species and habitats. The example workflow and accompanying suite of utilities facilitate the production of TPPs with R or Excel. TPPs created using bat pass data revealed inter- and intra-specific differences in temporal activity that would normally be missed by typical assessments, which tend to measure bat activity using the total, or average, number of bat passes recorded on each night. This analysis illustrates how TPPs are capable of revealing useful insights into bat behaviour and expanding the scope of information acquired by PAM. TPPs provide an intuitive means of visualising patterns of bat activity over prolonged periods of time. With further study, activity patterns within TPPs could be related to specific behaviours such as roosting and commuting, enabling more detailed assessments of habitat use. Although bats are ideal candidates for TPPs, this technique could also be adapted for other species that can be monitored using time-stamped acoustic data.