Polar Biology 24, 460-466 (2001)
Feeding strategies of free-ranging Adelie penguins, Pygoscelis adeliae, analysed by multiple data recording.
Ropert-Coudert Y, Kato A, Baudat J, Bost C-A, Le Maho Y, Naito Y
The fine-scale feeding behaviour of free-ranging Adelie penguins (Pygoscelis adeliae) during a single foraging trip was investigated by monitoring three parameters simultaneously at a frequency of 1Hz, these being; depth, swim speed and oesophagus temperature. Ingestion events were detected as abrupt drops in the oesophageal temperature and related to the birdsŐ foraging behaviour. Although, a high percentage of oesophageal temperature loggers were rejected, one complete foraging trip was recorded for all the three parameters from one bird while 92 and 67% of the foraging trip was recorded for two other birds. 12.3% of the temperature drops occurred at surface but they were mainly small, except 61 of them probably representing snow ingestion while the birds were on land. All other drops were observed during dives, 88% of them during the undulatory (and occasionally the ascent) phase of dives deeper than 40 m. The mean swim speed during non-feeding shallow and V-shaped dives was relatively constant throughout the dive around 2.1 m/s, whereas during W-shaped deep dives, swim speed during the undulatory phase was lower (1.71 m.s-1) than during the descent and ascent and was characterized by a series of rapid accelerations and decelerations. 42.6% of these accelerations were followed by one or more ingestion events and birds swam upward in 60% of the accelerations. Such multiple data recording opens new tracks for the examination of the decision-making processes in foraging penguins.
PG01-3
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