Echolocation depths and acoustic foraging behavior of Baird's beaked whales (<i>Berardius bairdii</i>) based on towed hydrophone recordings
Annamaria I. DeAngelis, Jay Barlow, Daniel Gillies, Lisa T. Ballance
Abstract
Little is known about the foraging depths of Baird's beaked whales (Berardius bairdii). One Baird's beaked whale was tagged with a time-depth recorder in slope waters east of central Honshu, Japan (Minamikawa et al., 2007). In that study, five deep dives were observed with mean durations of 45.8 min (SD = 11.4) and mean maximum depths of 1,566 m (SD = 208). One Baird's beaked whale was tagged with a multi-sensor DTAG off southern California (Stimpert et al., 2014). In that study, two deep foraging dives were observed with durations of 55.7 and 81.7 min and maximum depths of 945 and 1,410 m, respectively. The portions of those dives with actual foraging behavior (near-constant echolocation and inverted swimming orientation) lasted 31.6 and 52.6 min, respectively. The mean foraging depths were not reported, but foraging behavior began at ~400 m and ended coincident with the beginning of their steep ascent. Both foraging dives in the California study were thought to reach the seafloor. In both prior studies (Japan and California), deep dives were interspersed among shorter dives to shallow (<100 m) and intermediate depths (100–1,000 m).