Vocal communication in adult greater horseshoe bats, Rhinolophus ferrumequinum

Abstract

Whereas echolocation in horseshoe bats is well studied, virtually nothing is known about characteristics and function of their communication calls. Therefore, the communication calls produced by a group of captive adult greater horseshoe bats were recorded during various social interactions in a free-flight facility. Analysis revealed that this species exhibited an amazingly rich repertoire of vocalizations varying in numerous spectro-temporal aspects. Calls were classified into 17 syllable types (ten simple syllables and seven composites). Syllables were combined into six types of simple phrases and four combination phrases. The majority of syllables had durations of more than 100 ms with multiple harmonics and fundamental frequencies usually above 20 kHz, although some of them were also audible to humans. Preliminary behavioral observations indicated that many calls were emitted during direct interaction with and in response to social calls from conspecifics without requiring physical contact. Some echolocation-like vocalizations also appeared to clearly serve a communication role. These results not only shed light upon a so far widely neglected aspect of horseshoe bat vocalizations, but also provide the basis for future studies on the neural control of the production of communicative vocalizations in contrast to the production of echolocation pulse sequences.

Vocalization during copulation behavior in greater horseshoe bats, Rhinolophus ferrumequinum

“…In communication systems of animal, a repertoire of graded signals, each used in a variety of contexts, allows to transfer finely detailed information. Ma et al [28] reported the greater horseshoe bats have a variety of communication calls with 17 syllable types combined into at least six types of simple phrases and four combination phrases [28]. Therefore, we predict that greater horseshoe bats would produce communication calls with very different spectral and temporal characteristics compared to echolocation calls during copulation.…”

“…The rooms had regulated light-dark cycles adjusted with an astronomical light timer to the natural photoperiod for Beijing. The environment of the rooms, as well the feeding methods for keeping the bats has been described elsewhere [28].…”

“…Each time, we separated two randomly chosen individuals (1 male and 1 female, bats gender determined at capture) from the colony and transferred them into an observation cage (wire mesh cage with wire bottom; dimensions 0.6 m×0.6 m×1 m; width of mesh 1 cm×1.5 cm). The cage was positioned in the center of one room, separated from the free-flying bats by closing the sliding door [28]. The 2 individuals were kept in the observation cage for up to 12 h with food and water for calls and behaviors recording.…”

Social calls used by a leaf-roosting bat to signal location

“…In bats, most acoustic communication research has focused on echolocation, with little effort aimed at documenting the diversity and function of social calls. Compared with echolocation calls, social calls are longer, more broadband and highly complex, with extensive spectral variability and use of syllables and phrases (Ma et al 2006). Further, bats often maintain a diverse repertoire of social calls that are used in a variety of social contexts (Bohn et al 2008).…”

Sensory feedback control of mammalian vocalizations

“…. Many if not all bats emit a broad repertoire of social communications sounds, some of which closely resemble echolocation calls and some of which are totally dissimilar to and perhaps even acoustically maladaptive as echolocation calls [57,64,77]. Does auditory feedback influence vocalizing similarly in both echolocation and communication contexts?…”