Efficacy of anuran trapping and monitoring techniques in the tropical forests of Bioko Island, Equatorial Guinea: Supplementarty material

Anurans are of particular importance in monitoring the ecosystems of tropical environments. Existing literature reveals little standardization in methodology, and many of the techniques that have been shown to be effective in deciduous environments, such as polyvinyl chloride (PVC) refuges and pitfall traps, are either inadequate or too difficult to implement in tropical environments. This study evaluated three anuran trapping and monitoring techniques for use in a tropical environment: PVC pipe refuges, pitfall traps, and anuran census. Prior research validated the use of PVC refuges and pitfall traps in deciduous forests, but their use outside of the Americas has not been thoroughly examined. PVC refuges failed to attract anurans in this study, likely due to the abundance of natural refugia characteristic of tropical environments with dense foliage. Pitfall traps utilizing 19-liter buckets are difficult to implement in rocky soil and were shown to be ineffective utilizing buckets small enough to implement in this research. The modifications to the pitfall traps made in this research allowed for effective use with smaller, easier to install buckets. The anuran census described in this study utilizes established trails or paths for a continuous census. This study shows evidence for the effective utilization of both modified pitfall trapping and anuran census in monitoring population densities, assessing species richness, and detecting the presence of rare or cryptic species.