Dear marmam, It is our pleasure to share our recent publication on the biosonar and movement strategy of Sowerby's beaked whales. The first biologging data on this species, from individuals tagged off Terceira, Azores with Dtags, showed surprisingly fast swimming and hunting behaviour, combined with fast, high frequency echolocation. These findings suggest a much wider range of deep-sea foraging niches and strategies in beaked whales than currently expected, as well as a possibly different beaked whale response strategy to anthropogenic sounds. Link to the open access paper: https://journals.biologists.com/jeb/article/225/9/jeb243728/275372/Sowerby-s... Authors: Fleur Visser, Machiel G Oudejans, Onno A Keller, Peter T Madsen and Mark Johnson. Abstract: Closely-related species are expected to diverge in foraging strategy, reflecting the evolutionary drive to optimize foraging performance. The most speciose cetacean genus, the mesoplodonts, are beaked whales with little diversity in external morphology or diet, and overlapping distributions. Moreover, the few studied species of beaked whales (Ziphiidae) show closely-similar foraging styles with slow, energy-conserving movement during long, deep foraging dives. This raises the question of what factors drive their speciation. Using data from animal-attached tags and aerial imagery, we test the hypothesis that two similar-sized mesoplodonts, Sowerby's (Mesoplodon bidens) and Blainville's (M. densirostris) beaked whales, exploit a similar low-energy niche. We show that, compared to the low-energy strategist Blainville's beaked whale, Sowerby's beaked whale lives in the fast lane. While targeting a similar meso/bathypelagic foraging zone, they consistently swim and hunt faster, perform shorter deep dives, echolocate at a faster rate and with higher frequency clicks. Further, extensive near-surface travel between deep dives challenges the interpretation of beaked whale shallow inter-foraging dives as management of decompression sickness. The distinctively higher frequency echolocation clicks do not hold apparent foraging benefits. Instead, we argue that a high-speed foraging style influences dive duration and echolocation behaviour, enabling access to a distinct prey population. Our results demonstrate that beaked whales exploit a broader diversity of deep-sea foraging and energetic niches than hitherto suspected. The marked deviation of Sowerby’s beaked whales from the typical Ziphiid foraging strategy has potential implications for their response to anthropogenic sounds, which appear to be strongly behaviourally-driven in other Ziphiids.