Neotropical bats as indicators of environmental disturbance: what is the emerging message?

Science has searched for tools to indicate, measure or predict the responses of organisms to environmental disturbances. Neotropical bats have been identified as potential indicators and the number of articles using them is increasing. But contradictory results indicate the need to assess the viability to widely use bats for that purpose. A review on bat responses to forest fragmentation, logging, agricultural conversion or plant sucession was performed to detect patterns and problems, and to identify what is the emerging message. Variations of up to 17 times in the number of replicates, 360 times in the size of experimental areas, 166 times in the size of control areas, and 36 times in captures were detected. Almost 90% of the studies used mistnets, resulting in analyses biased towards phyllostomids. No clear pattern was observed regarding bat responses to the disturbances tested, from no effects on species richness between fragments and control areas, to higher abundances in the surrounding matrices. Most of the studies indicated species-specific responses, and conclusions were based, on average, on 20 species, a fraction of the regional richness. Neotropical bats should be used cautiously as indicators and generalizations should be avoided. Despite the problems identified, bats may contribute to the study of the topic in the Neotropics, as long as basic precautions are followed.