title: Avian orientation: the pulse effect is mediated by the magnetite receptors in the upper beak.
abstract: 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.
authors.affiliation: Fachbereich Biowissenschaften der J.W. Goethe-Universität, 60054 Frankfurt am Main, Germany. wiltschko@bio.uni-frankfurt.de
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wiltschko
authors.forename: Ursula
authors.initials: U
authors.lastname: Munro
authors.forename: Hugh
authors.initials: H
authors.lastname: Ford
authors.forename: Roswitha
authors.initials: R
authors.lastname: Wiltschko