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Flight speeds of two seabirds: a test of Norberg's hypothesis

Authors

  • KYLE HAMISH ELLIOTT,

    1. Canadian Wildlife Service, National Wildlife Research Centre, Carleton University, Ottawa, K1A 0H3, Canada
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  • ANTHONY J. GASTON

    Corresponding author
    1. Canadian Wildlife Service, National Wildlife Research Centre, Carleton University, Ottawa, K1A 0H3, Canada
      *Corresponding author.
      Email: tony.gaston@ec.gc.ca
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*Corresponding author.
Email: tony.gaston@ec.gc.ca

Abstract

Norberg suggested that birds should increase their flight speed when rearing chicks in order to maximize chick energy intake by reducing commuting time. We measured the incubation and chick-rearing flight speeds of a medium-range (Brünnich's Guillemot Uria lomvia) and long-range (Northern Fulmar Fulmarus glacialis) forager near the Prince Leopold Island colony, Nunavut, Canada. The mean flight speed for the long-range forager was significantly higher during chick-rearing than during incubation. The medium-range forager showed no difference in mean flight speed during the two periods. We suggest that because petrels fly close to their minimum power velocity and have a low wing-loading, whereas alcids fly close to their maximum range velocity and have a high wing-loading, petrels have a greater ability than alcids to alter their flight speed according to changes in the demands of different breeding stages. Consequently, whereas Northern Fulmars adapt to the additional cost of chick-rearing partially by altering flight speed, Brünnich's Guillemots can only do so by reducing mass.

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Ancillary