Using an omnidirectional video logger to observe the underwater life of marine animals : humpback whale resting behaviour

Abstract

This study was supported by the Bio-Logging Science of the University of Tokyo (UTBLS) program, the Japan Society for the Promotion of Science Postdoctoral Fellowships Research Abroad, the Japan Society for the Promotion of Science (grant number 17H00776 K.S), the Japan Society for the Promotion of Science Bilateral Open Partnership Joint Research Program, the Mitsui and Co. Environment Fund, and The Research Grant against Global Warming of the Ichimura Foundation for New Technology.Animal-borne video loggers are powerful tools for investigating animal behaviour because they directly record immediate and extended peripheral animal activities; however, typical video loggers capture only a limited area on one side of an animal being monitored owing to their narrow field of view. Here, we investigated the resting behaviour of humpback whales using an animal-borne omnidirectional video camera combined with a behavioural data logger. In the video logger footage, two non-tagged resting individuals, which did not spread their flippers or move their flukes, were observed above a tagged animal, representing an apparent bout of group resting. During the video logger recording, the swim speed was relatively slow (0.75 m s ), and the tagged animal made only a few strokes of very low amplitude during drift diving. We report the drift dives as resting behaviour specific to baleen whales as same as seals, sperm whales and loggerhead turtles. Overall, our study shows that an omnidirectional video logger is a valuable tool for interpreting animal ecology with improved accuracy owing to its ability to record a wide field of view.Publisher PDFPeer reviewe