title: Night-migratory songbirds possess a magnetic compass in both eyes.
abstract: Previous studies on European robins, Erithacus rubecula, and Australian silvereyes, Zosterops lateralis, had suggested that magnetic compass information is being processed only in the right eye and left brain hemisphere of migratory birds. However, recently it was demonstrated that both garden warblers, Sylvia borin, and European robins have a magnetic compass in both eyes. These results raise the question if the strong lateralization effect observed in earlier experiments might have arisen from artifacts or from differences in experimental conditions rather than reflecting a true all-or-none lateralization of the magnetic compass in European robins. Here we show that (1) European robins having only their left eye open can orient in their seasonally appropriate direction both during autumn and spring, i.e. there are no strong lateralization differences between the outward journey and the way home, that (2) their directional choices are based on the standard inclination compass as they are turned 180° when the inclination is reversed, and that (3) the capability to use the magnetic compass does not depend on monocular learning or intraocular transfer as it is already present in the first tests of the birds with only one eye open.
authors.affiliation: AG Neurosensorik/Animal Navigation, IBU & Research Center for Neurosensory Sciences, Carl-von-Ossietzky-University of Oldenburg, Oldenburg, Germany.
authors.forename: Svenja
authors.initials: S
authors.lastname: Engels
authors.forename: Christine Maira
authors.initials: CM
authors.lastname: Hein
authors.forename: Nele
authors.initials: N
authors.lastname: Lefeldt
authors.forename: Helmut
authors.initials: H
authors.lastname: Prior
authors.forename: Henrik
authors.initials: H
authors.lastname: Mouritsen
mesh_terms: D000375:Aging / Q000502:physiology; D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D003624:Darkness; D060526:Magnetic Fields; D009799:Ocular Physiological Phenomena; D009949:Orientation / Q000502:physiology*; D012621:Seasons; D020308:Songbirds / Q000502:physiology*; D014795:Visual Pathways