Echolocation call design by aerial insectivorous bats in lowland tropical forest

High-flying aerial insectivorous bats are difficult to catch with conventional mist-netting, and are, therefore, generally underrepresented in most bat studies. However, acoustic recordings can be used rather easily to monitor and identify these bat species since most of them emit species-specific echolocation calls while searching for prey. Using custom-made ultrasound recording equipment and software, we compiled a collection of characteristic call types. The calls are mainly composed of narrow-band constant-frequency calls and frequency-modulated calls. Calls are characterized by long duration, long pulse-interval, and low frequency, and are mostly uniharmonic. This type of call is presumably adapted for long-range prey detection, as well as for analysis of insect-flutter information.