Echolocation signals of the greater horseshoe bat (Rhinolophus ferrumequinum) in transfer flight and during landing. 1997

B Tian, and H U Schnitzler
Lehrstuhl Tierphysiologie, Universität Tübingen, Germany.

Echolocation signals of horseshoe bats (Rhinolophidae) consist of a relatively long component of constant frequency (CF) which is preceded by an initial frequency-modulated (iFM) component and followed by a terminal frequency-modulated (tFM) component. To examine the role of these components in echolocation, four bats were trained to fly from a perch to a landing bar. A dual camera system allowed reconstruction of the flight paths in three dimensions. Echolocation signals were recorded, analyzed, and correlated with the flight behavior of the bats. It was confirmed that during flight the bats compensate the Doppler shifts which are produced by their own flight movement. In free flight they emit per wing beat one single signal of long duration, with little variation in the three signal components. In approach flight the bats reduce pulse duration and interval with decreasing target range. The iFM is not varied with respect to target range, suggesting that this component plays little role in the processing of echolocating a target of interest. The bandwidth of the tFM component is increased while its duration is shortened in proportion to decreasing target range, so that the signal-echo overlap of the FM component is avoided down to a target distance of 15 cm. These concurrent changes suggest that the tFM component is used for ranging. During the last 60 cm of the approach the bats compensated for the increase of echo SPL by lowering the emission level of the CF component by 6-9 dB and that of the tFM component by 9-11 dB per halving of range. The specific signal structure of horseshoe bats is discussed as an adaptation for the hunting of fluttering insects in highly cluttered environments.

UI MeSH Term Description Entries
D002685 Chiroptera Order of mammals whose members are adapted for flight. It includes bats, flying foxes, and fruit bats. Bats,Flying Foxes,Horseshoe Bats,Pteropodidae,Pteropus,Rhinolophus,Rousettus,Bat, Horseshoe,Bats, Horseshoe,Foxes, Flying,Horseshoe Bat
D004455 Echolocation An auditory orientation mechanism involving the emission of high frequency sounds which are reflected back to the emitter (animal). Echolocations
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D001522 Behavior, Animal The observable response an animal makes to any situation. Autotomy Animal,Animal Behavior,Animal Behaviors

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