S3-1.6 Friday, Jan. 4 Flight performance and echolocation behavior in aerial insectivorous bats JONES, G*; HOLDERIED, M.W.; University of Bristol; University of Bristol Gareth.Jones@bris.ac.uk
Bats are among the few predators that can exploit the large quantities of aerial insects that are active at night. They do this by using echolocation to detect, localize and classify targets in the dark. Echolocation calls are shaped by natural selection to match ecological challenges. For example, bats flying in open habitats typically emit calls of long duration, with long pulse intervals, shallow frequency modulation and containing low frequencies. As obstacles or prey are approached, call structure changes in predictable ways for several reasons: calls become shorter to reduce overlap between pulse and echo, and calls change in shape so that localization errors are minimized. Echolocation behaviour and flight performance are closely synchronized: we have monitored both features simultaneously by using stereo photo- and videogrammetry, and by acoustic flight path tracking. These methods have allowed us to quantify the intensity of signals used by free-living bats, and can show systematic changes in signal design in relation to obstacle proximity. We show how signals emitted by aerial-feeding bats can be among the most intense airborne sounds in nature, and how bats adjust signal design so that Doppler-related range overestimation compensates for range underestimation caused by the batís movement in flight. We show the potential of our methods for understanding interactions between echolocating bats and prey that have evolved ears to detect bat calls.