Habitat disturbance affects, directly or indirectly, the predation risk and food available to animals. One group of animals that may be negatively affected by habitat disturbance are forest-dependent aerial insectivorous bats, especially in the Amazon rainforest, where forest clearance and degradation continue unabated. However, we still have a limited understanding of the mechanisms underlying the negative effect of habitat disturbance on forest aerial insectivorous bats. Evaluating the changes in prey-predator interaction in disturbed habitats can provide helpful information for protected area management. We evaluated how predation risk, insect biomass, and moonlight intensity affect bat activity levels in continuous primary and disturbed forests (fragments and secondary forest) at the Biological Dynamics of Forest Fragments Project, Central Amazon, Brazil. We sampled bats using autonomous ultrasound recorders in continuous forest, forest fragments, and secondary forest. To assess insect biomass, we placed malaise traps close to the recorders and conducted a playback experiment consisting of owl calls to assess the influence of increased predation risk by natural predators on bat activity. We found that continuous forest had higher bat activity than fragments and secondary forest, probably reflecting higher insect biomass in continuous primary forest compared to secondary forest. Insect biomass was the best predictor of activity in disturbed habitats compared to predation risk and moonlight. Predation risk did not modulate bat activity in any habitat type. The effect of moonlight intensity on activity was only apparent in three species in different habitats. Our results suggest that these responses were related to the abundance of specific insect orders and not predation risk. Overall, our findings emphasize the importance of evaluating the effects of prey-predator interactions on the distribution of bats in disturbed tropical forests, as habitat disturbance can negatively affect lower trophic levels and consequently influence not only bats but other insect consumers.
