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Marine Ecology Progress Series

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MEPS 370:285-294 (2008)  -  DOI:

Linear tracks and restricted temperature ranges characterise penguin foraging pathways

P. N. Trathan1,*, C. Bishop2, G. Maclean3, P. Brown3, A. Fleming1, M. A. Collins1

1British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 0ET, UK
2School of Biological Sciences, University of Wales, Deiniol Road, Bangor LL57 2UW, UK
3Navsys Ltd, Springwood House, Linburn Road, Kirknewton, Edinburgh EH27 8DY, UK

ABSTRACT: Marine predators are thought to follow sophisticated scale-dependent search strategies when seeking patchy and unpredictable prey. However, fine-scale information about these strategies has hitherto been difficult to obtain for diving predators that often remain at the sea surface for only limited periods of time. Using ARGOS telemetry and novel, low-powered, archival GPS, we followed the fine-scale at-sea behaviour of king penguins breeding on South Georgia. Results revealed that foraging pathways were generally linear, except at the finest scale, where movements probably reflected either fine-scale searching behaviour, or fine-scale random movements associated with having found prey. King penguins focused 45% of their foraging effort in waters with a specific surface temperature (5.0 to 5.5°C)—an environmental cue potentially important in helping them locate prey, thereby reducing their need to expend energy in area-restricted search patterns. Within these waters, penguins slowed down and increased their dive effort and degree of meandering. First Passage Time analysis revealed that penguins focused much of their effort at local scales, generally in areas with a radius of 2 km. In these areas, penguins dived marginally deeper and targeted waters that were significantly warmer at the bottom of their dives. Such information about fine-scale foraging behaviour will help increase our understanding of the environmental correlates that characterise areas where marine predators exploit their prey. The scale of these behavioural processes is better resolved using the fine-scale temporal and spatial resolution of GPS tracking data.

KEY WORDS: Foraging · GPS telemetry · Archival GPS · Environmental cues · King penguin · Diving predators · Antarctic Polar Front · South Georgia

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Cite this article as: Trathan PN, Bishop C, Maclean G, Brown P, Fleming A, Collins MA (2008) Linear tracks and restricted temperature ranges characterise penguin foraging pathways. Mar Ecol Prog Ser 370:285-294.

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