Ultrasound Social Calls Made by Greater Horseshoe Bats (Rhinolophus ferrumequinum) in a Nursery Roost

Abstract

Ultrasound calls made by adult Rhinolophus ferrumequinum in a nursery roost were recorded using a time expansion detector with a microphone on an extension cable. Initial analysis showed that in addition to the echolocation calls at 81–84 kHz there were ultrasound calls at lower frequencies. Simultaneous recordings of ultrasound and low frequency signals (1–10 kHz) showed that echolocation pulses, ultrasound social calls and low frequency social calls were quite distinct in both duration, frequency and number of calls. Twelve types of ultrasound social calls were identified. The majority of calls were in the range 20–29 kHz and 1–49 ms duration. Variability was found in the relative power of the fundamental and harmonics of the calls. This analysis has identified a substantial repertoire of calls used by R. ferrumequinum in a nursery roost colony. The possibility of the use of a male advertisement call in the roost is discussed.