Dear Colleagues, The following paper has been published: Three-dimensional resting behaviour of northern elephant seals: drifting like a falling leaf Yoko Mitani, Russel D. Andrews, Katsufumi Sato, Akiko Kato, Yasuhiko Naito and Daniel P. Costa Biol. Lett. (2010) 6, 163–166 Abstract: During their long migrations through the Pacific, northern elephant seals, Mirounga angustirostris, never haul out on land and they rarely spend more than a few minutes at a time at the surface. They are almost constantly making repetitive, deep dives, raising the question of when do they rest? One type of dive, the drift dive, characterized by a time-depth profile with a phase of lower than average descent speed is believed to be a resting dive. To examine the behaviour of seals during drift dives, we measured body position and three-dimensional diving paths of six juvenile seals. We found that seals rolled over and sank on their backs during the drift phase, wobbling periodically so that they resembled a falling leaf. This enabled seals to drastically slow their descent rate, possibly so that negatively buoyant seals can rest without ending up in the abyss. This reduces the work required to return to the surface to breath, and allows them time to rest, process food or possibly sleep during the descent phase of these dives where they are probably less susceptible to predation. Keywords: northern elephant seals; drift dives; three-dimensional diving behaviour Reprints (pdf) available from the first author (yo_mitani@fsc.hokudai.ac.jp). Cheers, Yoko Yoko MITANI Laboratory of Marine Ecosystem Change Analysis Field Science Center for the Northern Biosphere Hokkaido University 3-1-1 Minato, Hakodate, Hokkaido 041-8611 JAPAN TEL&FAX: +81-138-40-8836 E-mail: yo_mitani@fsc.hokudai.ac.jp