MEPS 188:305-309 (1999)  -  doi:10.3354/meps188305

A tropical bird in the Arctic (the cormorant paradox)

David Grémillet1,*, Rory P. Wilson2, Sarah Wanless1, Gerrit Peters2

1Institute of Terrestrial Ecology, Banchory Research Station, Hill of Brathens, Glassel, Banchory AB31 4BY, Scotland, UK
2Institut für Meereskunde Kiel, Abteilung Meereszoologie, Düsternbrooker Weg 20, 24105 Kiel, Germany

ABSTRACT: Seabirds, like all marine endotherms, have to compensate for the extensive cooling effect of water when diving. Alone among them, cormorants (Phalacrocoracidae) have a wettable plumage and are predicted to require disproportionately large amounts of food to balance heat losses. These piscivorous birds are thus thought to have a detrimental impact on fish stocks. However, we show here that even in great cormorants from Greenland, which dive in water at 3 to 7°C, daily food intake is lower than for well-insulated European seabirds. Despite their wettable plumage, cormorants thus appear to manage their energy budgets in a remarkably efficient way. Nevertheless, the specific foraging strategies which enable this performance make cormorants dependent on high prey density areas, a feature that should be taken into account by future management plans.

KEY WORDS: Diving endotherms · Cormorants · Insulation · Food requirements · Prey

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