Sensory challenges for trawling bats: Finding transient prey on water surfaces.
Bats are able to identify obstacles and prey objects based exclusively on acoustic information acquired via echolocation. To assess the echo information potentially available to the trawling bat Noctilio leporinus, prey objects were ensonified with artificial bat calls and deduced echo target strengths (TS) of the reflected signals. The artificial calls consisted either of constant frequency (CF) or frequency modulated (FM) sounds. Detection distances were calculated for call intensities of N. leporinus emitted in the field and in confined space. Measurements of a transient target consisting of a brief water splash and subsequently expanding water ripples revealed that concentrically expanding water ripples can provide sufficiently loud echoes to be detected by trawling bats. Experiments with stationary targets revealed differences in TS depending on the type of signal used (CF or FM). A calculated maximum detection distance between 4.5 and 13.7 m for all measured targets indicates that prey detection in this very loud calling species occurs much earlier than suggested by estimations based on modifications in echolocation or flight behavior.
Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Albert-Einstein-Allee 11, Ulm, Germany.
Kirstin
K
Übernickel
Department of Sensor Technology, Friedrich-Alexander University Erlangen-Nuremberg, Erlangen, Germany.
Ralph
R
Simon
Institute of Experimental Ecology, University of Ulm, Albert-Einstein-Allee 11, Ulm, Germany.
Elisabeth K V
EK
Kalko
Institute of Evolutionary Ecology and Conservation Genomics, University of Ulm, Albert-Einstein-Allee 11, Ulm, Germany.
Marco
M
Tschapka
D000161:Acoustic Stimulation / Q000379:methods; D000162:Acoustics; D000818:Animals; D001307:Auditory Perception; D002685:Chiroptera / Q000523:psychology*; D004455:Echolocation; D005247:Feeding Behavior; D005426:Flight, Animal; D011235:Predatory Behavior; D013017:Sound Localization; D013018:Sound Spectrography; D013499:Surface Properties; D013997:Time Factors; D014867:Water
D014867:Water