Flight speeds of two seabirds: a test of Norberg's hypothesis
Article first published online: 10 AUG 2005
Volume 147, Issue 4, pages 783–789, October 2005
How to Cite
ELLIOTT, K. H. and GASTON, A. J. (2005), Flight speeds of two seabirds: a test of Norberg's hypothesis. Ibis, 147: 783–789. doi: 10.1111/j.1474-919x.2005.00462.x
- Issue published online: 10 AUG 2005
- Article first published online: 10 AUG 2005
- Received 4 October 2004; revision accepted 10 June 2005.
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.