Vocalization during copulation behavior in greater horseshoe bats, Rhinolophus ferrumequinum

Vocal communication plays an important role for individual recognition and male-female interaction during mating in greater horseshoe bats, especially in respect to mate fidelity, which ensures that the bats can maintain a stable social organization. Few studies, however, have addressed the calling behavior during copulating in bats. Here, we initially report the copulation vocalizations and behaviors of both male and female greater horseshoe bats. During copulation, the male assumed a dorsal position and arched his back, arming around the female using his feet and thumbs. The male repeatedly produced very short constant frequency (SCF) syllables with high intensity and repetition rate (male 1: 16.48±4.8 ms, male 2: 17.79±4.03 ms) when he tried to insert the penis into the female, and then long syllables (male 1: 42.08±12.67 ms, male 2: 43.02±11.44 ms) after penile insertion. The female bats sometime refused the male bats in the early phase of copulations as emitting noise bursts and broad-band vocalizations, but kept silence during actual copulation. We also found that the SCF copulation calls of one male remained stable peak frequencies on different copulation days although its echolocation call frequency varied each day. Moreover, different male individuals maintained their own “private frequency” in the SCF copulation calls. Therefore, we predicted that the SCF copulation calls may serve as an indicator for female greater horseshoe bats to recognize the mating males in order to maintain mate fidelity because horseshoe bats exhibit sexual segregation before mating. Our results stipulate further studies on mating system and copulation strategies in polygynous bats. Such work may also aid in promoting the preservation of greater horseshoe bats.