[MARMAM] New paper on 3D resting behavior of northern elephant seals

Yoko Mitani yo_mitani at fsc.hokudai.ac.jp
Mon Mar 15 18:27:19 PDT 2010


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 at 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 at fsc.hokudai.ac.jp




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