Ultrasound social calls of greater horseshoe bats (Rhinolophus ferrumequinum) in a hibernaculum

Abstract

ABSTRACT Ultrasound calls made by adult Rhinolophus ferrumequinum in a hibernaculum in early October were recorded using a time expansion detector during two 24 hrs periods. In addition to echolocation calls (83–84 kHz), ultrasound social calls were recorded, similar to those recorded previously in a nursery roost. The recordings also included social calls not found in the repertoire of the nursery roost colony from late April until early October. These were multiple component ultrasound social calls with six or seven components and prolonged trill calls. The trill call frequency varied periodically over a range of 2.9 ± 1.7 kHz about the mean with a period of 8.0 ± 3.1 ms. The trill calls and very long ultrasound social calls have not been reported previously. The possibility that the trill calls may be used by male bats as advertisement calls in the cave is discussed.