Echolocation inter-click interval variation among specific behaviours in free-ranging bottlenose dolphins from the coast of Uruguay

Abstract

To assess whether behaviour can be inferred from echolocation trains (inter-click intervals) this study examines acoustic recordings of free-ranging bottlenose dolphins using Passive Acoustic Monitoring (PAM). Inter-click intervals from 17 groups of free-ranging bottlenose dolphins were monitored over a 36 day period in an area within the Cerro Verde (Marine Protected Area), Uruguay. Simultaneous visual observations were made from shore nearby. Results show that inter-click intervals in the echolocation trains had significant differences for three specific behaviours: feeding, socialising and travelling. The natural environment was quiet, with no disturbances in the immediate vicinity from boats, drones or other man-made noises.

A WAV file dataset of bottlenose dolphin whistles, clicks, and pulse sounds during trawling interactions

“…These observations indicate that the present database recorded at 192 kHz could be suitable for the majority of dolphin vocalization analyses. To support this, it is important to note that numerous studies on the high-frequency echolocation clicks of bottlenose dolphins utilized this (or a lower) sampling frequency 37 – 39 . However, for other purposes, such as the fine identification or classification of dolphin species, the recording of the full bandwidth is recommended.…”