Acta Medica BelgicaSociété Royale Belge de Médecine Physique et de Réhabilitation
[en] ultrasounds ; bat ; antipredator behaviour
[en] Ultrasounds are produced and heared by a great variety of animals. Every zoological group considered has its own system of emission/audition. Ultrasounds appear to be used only in order to exchange some information with other members of a group or to echolocate i.e. to detect possible preys or obstacles with a sonar like system. The best know echolocating mammals are cetaceans and bats. Bats produce two kinds of ultrasonic signals: constant frequency emissions and frequency modulated pulses. Pure tones allow quick detection and identification of the prey, whereas echoes of FM pulses carry valuable informations on the quality of sound reflecting surfaces. Despite these highly sophisticated detection systems, the preys, mainly moths, can sometimes escape their predator. Some of the adopt an irregular flight, others are able deter the bats or to jam their echolocation clicks.