title: Dugong (Dugong dugon) vocalization patterns recorded by automatic underwater sound monitoring systems.
abstract: To quantitatively examine the diurnal, or tidal, effects on dugong behavior, we employed passive acoustic observation techniques to monitor the animals. Automatic underwater sound monitoring systems for dugongs (AUSOMS-D) were deployed on the sea floor at depths of about 5 m south of Talibong Island, Thailand. The AUSOMS-D recorded underwater sound in stereo at a sampling frequency of 44.1 kHz for more than 116 consecutive hours. Dugong calls were automatically detected by newly developed software with a detection rate of 36.1% and a false alarm rate of 2.9%. In total, 3453 calls were detected during the 164 h of recording. The autocorrelation of the call rate indicated an attendance cycle of about 24 or 25 h, and the most frequent vocalizations were observed from 0300 to 0500 h. The calculated bearings of the sound sources, i.e., dugongs, were used as an indicator to track the relative numbers of dugongs during the monitoring periods.
authors.affiliation: Graduate School of Informatics, Kyoto University, 606-8501 Kyoto, Japan. ichikawa@bre.soc.i.kyoto-u.ac.jp
authors.forename: Kotaro
authors.initials: K
authors.lastname: Ichikawa
authors.forename: Chika
authors.initials: C
authors.lastname: Tsutsumi
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Arai
authors.forename: Tomonari
authors.initials: T
authors.lastname: Akamatsu
authors.forename: Tomio
authors.initials: T
authors.lastname: Shinke
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hara
authors.forename: Kanjana
authors.initials: K
authors.lastname: Adulyanukosol
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D002940:Circadian Rhythm / Q000502:physiology*; D020454:Dugong / Q000502:physiology*; D013018:Sound Spectrography / Q000295:instrumentation / Q000379:methods / Q000662:veterinary*; D013785:Thailand; D014828:Vocalization, Animal / Q000145:classification / Q000502:physiology*; D014872:Water Movements