[MARMAM] New paper on sperm whale diving and foraging behavior
Stephanie L. Watwood
swatwood at whoi.edu
Tue May 30 09:23:58 PDT 2006
The following paper on the diving and foraging behavior of sperm whales
was recently published:
Watwood, Stephanie L., Miller, Patrick J.O., Johnson, Mark, Madsen,
Peter T., and Tyack, Peter L. 2006. Deep-diving foraging behaviour of
sperm whales (Physeter macrocephalus). Journal of Animal Ecology 75:
Pdf reprints for those interested are available from swatwood at whoi.edu.
1. Digital tags were used to describe diving and vocal behaviour of
sperm whales during 198 complete and partial foraging dives made by 37
individual sperm whales in the Atlantic Ocean, the Gulf of Mexico and
the Ligurian Sea.
2. The maximum depth of dive averaged by individual differed across the
three regions and was 985 m (SD = 124·3), 644 m (123·4) and 827 m
(60·3), respectively. An average dive cycle consisted of a 45 min (6·3)
dive with a 9 min (3·0) surface interval, with no significant
differences among regions. On average, whales spent greater than 72% of
their time in foraging dive cycles.
3. Whales produced regular clicks for 81% (4·1) of a dive and 64% (14·6)
of the descent phase. The occurrence of buzz vocalizations (also called
'creaks') as an indicator of the foraging phase of a dive showed no
difference in mean prey capture attempts per dive between regions [18
buzzes/dive (7·6)]. Sperm whales descended a mean of 392 m (144) from
the start of regular clicking to the first buzz, which supports the
hypothesis that regular clicks function as a long-range biosonar.
4. There were no significant differences in the duration of the foraging
phase [28 min (6·0)] or percentage of the dive duration in the foraging
phase [62% (7·3)] between the three regions, with an overall average
proportion of time spent actively encountering prey during dive cycles
of 0·53 (0·05). Whales maintained their time in the foraging phase by
decreasing transit time for deeper foraging dives.
5. Similarity in foraging behaviour in the three regions and high diving
efficiencies suggest that the success of sperm whales as mesopelagic
predators is due in part to long-range echolocation of deep prey
patches, efficient locomotion and a large aerobic capacity during diving.
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Stephanie L. Watwood
Woods Hole Oceanographic Institution
Marine Research Facility MS#50
Woods Hole MA 02543
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