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The relative importance of physiological and behavioral adaptation in diving endotherms: a case study with great cormorants

Gremillet, D.; Wanless, S.; Boertmann, D. M.; Wilson, R. P.. 2006 The relative importance of physiological and behavioral adaptation in diving endotherms: a case study with great cormorants. Acta Zoologica Sinica, 52 (Supplement). 528-534.

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Abstract/Summary

Extensive morphological and physiological adjustments are assumed to underpin the adaptations of diving birds to high thermoregulatory costs. However, the role of behavioural adaptations has received little consideration. We have assessed the relative importance of physiological and behavioural adjustments in aquatic endotherms by studying the case of the poorly insulated great cormorant (Phalacrocorax carbo) in two contrasting thermal environments: Normandy (water temperature 12°C) and Greenland (water temperature 5°C). Major differences were found in the feeding behaviour of birds breeding in the two regions. Greenland birds showed a 70% reduction in time spent swimming relative to those in Normandy. Reduction in Greenland was achieved first by reducing time spent on the surface between dives and secondly by returning to land in between intensive bouts of diving. Total daily energy intake of cormorants was similar in both areas but prey capture rates in Greenland were 150% higher than those in Normandy. Our study shows that in a cold foraging environment, poorly insulated great cormorants significantly increase their foraging efficiency. To do this they rely on ecological adaptive patterns (minimization of time spent swimming in cold water and increased prey capture rates) far more than physiological adaptations (minimizing instantaneous costs). This finding supports predictions by Grémillet and Wilson (1999) that great cormorants can cope with a wide range of abiotic parameters despite their morphological handicaps, provided they can adjust their distribution to exploit dense prey patches.

Item Type: Publication - Article
Programmes: CEH Programmes pre-2009 publications > Biodiversity
CEH Sections: _ Biodiversity & Population Processes
Format Availability: Print
Additional Keywords: Diving endotherms, Great cormorant, Phalacrocorax carbo, Behavioural adaptation, Physiological adaptation, Energetics, Foraging behavior
NORA Subject Terms: Zoology
Date made live: 29 Jun 2007 11:19
URI: http://nora.nerc.ac.uk/id/eprint/345

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