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

The European free-tailed bat, Tadarida teniotis, forages in uncluttered airspace by using intense narrowband echolocation calls with low frequency (11-12 kHz), and feeds on relatively large flying insects, mainly (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, tympanate insects, which are less well represented in the diet of most other aerial-hawking bats. The results provide evidence in support of the 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.