Dear MARMAM community, My co-authors and I are very pleased to share our recent open access publication on cooperative feeding by herring-eating killer whales in Icelandic waters: Ellen L. Hayward, Filipa I. P. Samarra, Paul J. Wensveen, Anokhi Saha, Giorgia Giovannini, Kagari Aoki, Katsufumi Sato, Patrick J. O. Miller; Characterization of cooperative feeding dynamics and a novel acoustic indicator of prey capture in herring-eating killer whales. R Soc Open Sci. 1 June 2026; 13 (6): 260065. https://doi.org/10.1098/rsos.260065 Abstract: Group hunting is a widespread phenomenon, fundamentally shaping predator social dynamics and trophic interactions with their prey. The foraging behaviour of killer whale (Orcinus orca) groups feeding upon herring has been described as cooperative. In this study, we used animal-borne audio and video data to evaluate cooperative interactions and feeding rates of herring-eating killer whales in Icelandic waters. From video observations, whales appeared to stop herding herring following a tail-slap, feeding close to one another on individual stunned herring. By-product mutualism was identified, as whales consumed herring regardless of whether or not they conducted the tail-slap. A ‘slurping’ sound was recorded during 26% of video-confirmed consumption events, enabling us to estimate a mean (± s.d.) of 29.7 ± 25.3 herring consumed per tail-slap by the foraging group. Role specialization was indicated, with three tagged whales repeatedly occupying the ‘tail-slapping’ role more than expected by chance (p < 0.05). Only 8% of visually observed prey consumption events occurred in the absence of tail-slaps (‘whole-body attacks’), indicating that cooperative tail-slap feeding is more efficient than whole-body attacks. Our study confirms the highly social and cooperative nature of tail-slap feeding by killer whale groups and provides a novel method to estimate group-level feeding rates. Please feel free to reach out if you have any questions. All the best, Ellen Hayward [cid:552f0988-57a1-451f-a59a-1ee43c1748e1] Ellen Hayward (she/her) PhD Student Sea Mammal Research Unit, Scottish Oceans Institute, University of St Andrews, St Andrews, Fife, KY16 8BL The University of St Andrews is a charity registered in Scotland: No SC013532