Avian orientation: the pulse effect is mediated by the magnetite receptors in the upper beak.
Migratory silvereyes treated with a strong magnetic pulse shift their headings by approximately 90 degrees , indicating an involvement of magnetite-based receptors in the orientation process. Structures containing superparamagnetic magnetite have been described in the inner skin at the edges of the upper beak of birds, while single-domain magnetite particles are indicated in the nasal cavity. To test which of these structures mediate the pulse effect, we subjected migratory silvereyes, Zosterops l. lateralis, to a strong pulse, and then tested their orientation, while the skin of their upper beak was anaesthetized with a local anaesthetic to temporarily deactivate the magnetite-containing structures there. After the pulse, birds without anaesthesia showed the typical shift, whereas when their beak was anaesthetized, they maintained their original headings. This indicates that the superparamagnetic magnetite-containing structures in the skin of the upper beak are most likely the magnetoreceptors that cause the change in headings observed after pulse treatment.
Wiltschko
Wolfgang
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Fachbereich Biowissenschaften der J.W. Goethe-Universität, 60054 Frankfurt am Main, Germany. wiltschko@bio.uni-frankfurt.de
Munro
Ursula
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Ford
Hugh
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Wiltschko
Roswitha
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