It's not all about the Soprano: Rhinolophid bats use multiple acoustic components in echolocation pulses to discriminate between conspecifics and heterospecifics

PLoS One. 2018 Jul 18;13(7):e0199703. doi: 10.1371/journal.pone.0199703. eCollection 2018.

Abstract

Acoustic communication plays a pivotal role in conspecific recognition in numerous animal taxa. Vocalizations must therefore have discrete acoustic signatures to facilitate intra-specific communication and to avoid misidentification. Here we investigate the potential role of echolocation in communication in horseshoe bats. Although it has been demonstrated that echolocation can be used to discriminate among con- and hetero-specifics, the specific acoustic cues used in discrimination are still relatively unknown. Furthermore, the Acoustic Communication Hypothesis proposes that in multispecies assemblages, in which echolocation frequencies are likely to overlap, bats partition acoustic space along several dimensions so that each species occupies a discrete communication domain. Thus, multiple echolocation variables may be used in discrimination. The objective of this study was to investigate the potential of various echolocation variables to function as discriminatory cues in echolocation-based species discrimination. Using habituation-dishabituation playback experiments, we firstly tested the ability of Rhinolophus clivosus to discriminate between echolocation pulses of heterospecifics with either discrete or overlapping frequencies. Secondly, to determine whether R. clivosus could use echolocation variables other than frequency, we investigated its ability to discriminate among echolocation pulses differing in only one manipulated parameter. These test variables were identified by their contribution to the dissimilarity among pulses. Our results suggest that R. clivosus could discriminate readily between species using echolocation pulses with discrete frequencies. When frequencies overlapped, the ability of bats to discriminate was dependant on additional acoustic variables that defined the acoustic space occupied by the test signal. These additional acoustic variables included, but may not be restricted to, sweep rate of the FM and duty cycle. Thus, when echolocation pulses share a similar acoustic domain, bats use several cues to reliably discriminate among heterospecifics.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Communication
  • Animals
  • Chiroptera
  • Cues
  • Discrimination, Psychological*
  • Echolocation / physiology*
  • Habituation, Psychophysiologic
  • Sound

Grants and funding

This research was supported by grants to DSJ from the University of Cape Town (www.uct.ac.za) and the South African Research Chair Initiative of the Department of Science and Technology (http://www.dst.gov.za), administered by the National Research Foundation (http://www.nrf.ac.za), grant number—GUN 64798 and grants to AB from the NRF grant number DST88359. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.