title: Olfaction and topography, but not magnetic cues, control navigation in a pelagic seabird: displacements with shearwaters in the Mediterranean Sea.
abstract: Pelagic seabirds wander the open oceans then return accurately to their habitual nest-sites. We investigated the effects of sensory manipulation on oceanic navigation in Scopoli's shearwaters (Calonectris diomedea) breeding at Pianosa island (Italy), by displacing them 400 km from their colony and tracking them. A recent experiment on Atlantic shearwaters (Cory's shearwater, Calonectris borealis) breeding in the Azores indicated a crucial role of olfaction over the open ocean, but left open the question of whether birds might navigate by topographical landmark cues when available. Our experiment was conducted in the Mediterranean sea, where the availability of topographical cues may provide an alternative navigational mechanism for homing. Magnetically disturbed shearwaters and control birds oriented homeward even when the coast was not visible and rapidly homed. Anosmic shearwaters oriented in a direction significantly different from the home direction when in open sea. After having approached a coastline their flight path changed from convoluted to homeward oriented, so that most of them eventually reached home. Beside confirming that magnetic cues appear unimportant for oceanic navigation by seabirds, our results support the crucial role of olfactory cues for birds' navigation and reveal that anosmic shearwaters are able to home eventually by following coastal features.
authors.affiliation: Department of Biology, University of Pisa, Via Volta 6, 56126 Pisa, Italy.
authors.forename: Enrica
authors.initials: E
authors.lastname: Pollonara
authors.affiliation: Department of Biology, University of Pisa, Via Volta 6, 56126 Pisa, Italy.
authors.forename: Paolo
authors.initials: P
authors.lastname: Luschi
authors.affiliation: Department of Zoology, University of Oxford, South Parks Road, Oxford, UK.
authors.forename: Tim
authors.initials: T
authors.lastname: Guilford
authors.affiliation: Max Planck Institute for Ornithology, Department of Migration and Immuno-ecology, Schlossallee 2, Radolfzell 78315, Germany.|Dept. of Biology, University of Konstanz, 78468 Konstanz, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Wikelski
authors.affiliation: CNRS/CEFE, 1919, route de Mende, 34293 Montpellier Cedex 5, France.
authors.forename: Francesco
authors.initials: F
authors.lastname: Bonadonna
authors.affiliation: Department of Biology, University of Pisa, Via Volta 6, 56126 Pisa, Italy.
authors.forename: Anna
authors.initials: A
authors.lastname: Gagliardo
mesh_terms: D000818:Animals; D001717:Birds; D003463:Cues; D040362:Geographic Information Systems; D005843:Geography; D006702:Homing Behavior; D008522:Mediterranean Sea; D055696:Olfactory Perception; D065854:Spatial Navigation