LOW-FREQUENCY ECHOLOCATION ENABLES THE BAT TADARIDA-TENIOTIS TO FEED ON TYMPANATE INSECTS

The European free-tailed bat, Tadarida teniotis, forages in uncluttere d airspace by using intense narrowband echolocation calls with low fre quency (11-12 kHz), and feeds on relatively large flying insects, main ly (90 % by volume) of the tympanate orders Lepidoptera and Neuroptera . The use of low-frequency echolocation calls without strong harmonics appears to be a specialization for long-range detection of large, tym panate insects, which are less well represented in the diet of most ot her aerial-hawking bats. The results provide evidence in support of th e allotonic frequency hypothesis, i.e. that use of echolocation calls with frequencies above or below the best hearing of tympanate insects is an adaptation to increase the availability of these insects.