Colonial Waterbirds, 22, 120-129
Dive bouts and feeding sites of Adelie Penguins rearing chicks in an area with fast sea-ice
Y. Watanuki, Y. Miyamoto and A. Kato, 1999
Diving behavior and feeding sites of 22 Adelie Penguins (Pygoscelis adeliae) foraging at small open-water lands were simultaneously measured by bird-borne small data-loggers and land-based radio tracking in an area covered with fast sea-ice. The Adelies foraged in ice cracks along the shore in early and mid January and around icebergs in late January. We identified a minimum of 1.6-3.7 feeding sites per foraging trip, executing 3.2-6.2 dive bouts of 78-85 min. duration at feeding sites. Birds changed feeding sites during 9.6% of the inter-bout intervals but stayed within a site for 80.7% of the intervals. Duration of inter-bout intervals did not differ between birds changing feeding sites and those staying. Surface time to dive duration ratio increased with the dive sequence for dive bouts before leaving feeding sites, though this effect was not significant for those staying. Large variation in dive depth occurred within dive bouts, while dive bouts, feeding sites and sea depth had no strong effects on dive depth, indicating that penguins foraged at variable depth in mid and surface waters under the ice.
PG99-4
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