Mother-infant Vocal Communication and Development of Vocalization in Bats

Abstract

Mother-infant vocal communication and development of vocalization in several species of bats were studied under field and captive conditions. Newborn infant emit the most low frequency of attractive call. Within 2 weeks, infants gradually shift the frequency of their calls up to the ultrasonic range. Infant within 2 weeks actively does vocal exchange with returned mother from foraging. Change of vocal character in the course of development and character of time sequence of vocal exchange has been reported. In a CF (Constant Frequency) bat, Rhinolophus ferrumequinum nippon, the CF harmonics with 8kHz fundamental frequency gradually increases in frequency along the course of development. In a FM (Frequency Modulated) bat, Pipistrellus abramus, emit CF harmonics with 20kHz fundamental frequency at birth. In the course of development, CF sound with several harmonics increased downward FM steepness and shortened into the matured echolocation type signals.