title: Species-specific control of acoustic gaze by echolocating bats, Rhinolophus ferrumequinum nippon and Pipistrellus abramus, during flight.
abstract: Based on the characteristics of the ultrasounds they produce, echolocating bats can be categorized into two main types: broadband FM (frequency modulated) and narrowband CF (constant frequency) echolocators. In this study, we recorded the echolocation behavior of a broadband FM (Pipistrellus abramus) and a narrowband CF echolocator species (Rhinolophus ferrumequinum nippon) while they explored an unfamiliar space in a laboratory chamber. During flight, P. abramus smoothly shifted its acoustic gaze in relation to its flight direction, whereas R. ferrumequinum nippon frequently shifted its acoustic gaze from side to side. The distribution of the acoustic gazes of R. ferrumequinum nippon was twice as wide as that of P. abramus. Furthermore, R. ferrumequinum nippon produced double pulses twice as often as P. abramus. Because R. ferrumequinum nippon has a horizontal beam width (-6 dB off-axis angle) half as wide (±20.8 ± 6.0°) as that of P. abramus (±38.3 ± 6.0°), it appears to double the width of its acoustical field of view by shifting its acoustic gaze further off-axis and emitting direction-shifted double pulses. These results suggest that broadband FM and narrowband CF bats actively control their acoustic gazes in a species-specific manner based on the acoustic features of their echolocation signals.
authors: Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, 610-0321, Japan.
authors: Yasufumi
authors: Y
authors: Yamada
authors: Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, 610-0321, Japan. shiryu@mail.doshisha.ac.jp.|JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan. shiryu@mail.doshisha.ac.jp.
authors: Shizuko
authors: http://orcid.org/0000-0002-7106-1244
authors: S
authors: Hiryu
authors: Faculty of Life and Medical Sciences, Doshisha University, Kyotanabe, 610-0321, Japan.
authors: Yoshiaki
authors: Y
authors: Watanabe
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D002685:Chiroptera / Q000502:physiology*; D004455:Echolocation / Q000502:physiology*; D005106:Exploratory Behavior / Q000502:physiology; D005426:Flight, Animal / Q000502:physiology*; D012815:Signal Processing, Computer-Assisted; D013018:Sound Spectrography; D013045:Species Specificity; D013686:Telemetry; D014741:Video Recording
keywords: Acoustical field of view; Beam width; Microphone array; Pulse direction; Telemetry microphone