Samenvatting

This report is the result of a study done at the Smithsonian Tropical Research Institute, Panama. It is part of a bachelor thesis of the Forest- and Nature Management – Tropical Forestry Program at Van Hall Larenstein University of Applied Sciences, The Netherlands. This study is the first in a series of experiments on the effect of rain on tropical bats. Little is known about how bats are affected by rain. One fifth of all bat species are threatened. As increased global warming causes weather patterns to change, tropical regions will receive more precipitation. To establish adequate conservation programs the results of this series of studies could provide vital information. The aim of this preliminary study is to learn whether bats recognize rain noise, if this influences their roost emergence behavior, and whether it influences species differently. To test this, a speaker, capable of playing ultrasonic as well as sonic frequencies was placed in front of roost entrances of two different bat species. With this speaker the noise of rain and ambient noise, absent of rain, was played back on separate nights. The emergence behavior of the bats was recorded with a camera with a night-function. The videos were analyzed with event recording software. The results show that bats do delay their emergence when they are exposed to the noise of rain, while they do not delay their flight when exposed to ambient noise, absent of rain. The two study species did not show a difference in delay. This demonstrates that bats recognize the noise of rain and use this to evaluate their environment.