title: The magnetic map sense and its use in fine-tuning the migration programme of birds.
abstract: The Earth's magnetic field is one of several natural cues, which migratory birds can use to derive directional ("compass") information for orientation on their biannual migratory journeys. Moreover, magnetic field effects on prominent aspects of the migratory programme of birds, such as migratory restlessness behaviour, fuel deposition and directional orientation, implicate that geomagnetic information can also be used to derive positional ("map") information. While the magnetic "compass" in migratory birds is likely to be based on radical pair-forming molecules embedded in their visual system, the sensory correlates underlying a magnetic "map" sense currently remain elusive. Behavioural, physiological and neurobiological findings indicate that the sensor is most likely innervated by the ophthalmic branch of the trigeminal nerve and based on magnetic iron particles. Information from this unknown sensor is neither necessary nor sufficient for a functional magnetic compass, but instead could contribute important components of a multifactorial "map" for global positioning. Positional information could allow migratory birds to make vitally important dynamic adaptations of their migratory programme at any relevant point during their journeys.
authors.affiliation: AG Animal Navigation, Faculty of Biology/Environmental Sciences, University of Oldenburg, 26111, Oldenburg, Germany. dominik.heyers@uni-oldenburg.de.|Research Centre for Neurosensory Sciences, University of Oldenburg, 26111, Oldenburg, Germany. dominik.heyers@uni-oldenburg.de.
authors.forename: D
authors.identifier: http://orcid.org/0000-0002-2831-6985
authors.initials: D
authors.lastname: Heyers
authors.affiliation: AG Animal Navigation, Faculty of Biology/Environmental Sciences, University of Oldenburg, 26111, Oldenburg, Germany.|Research Centre for Neurosensory Sciences, University of Oldenburg, 26111, Oldenburg, Germany.|AG Biochemistry, Faculty of Medicine/Health Sciences, University of Oldenburg, 26111, Oldenburg, Germany.
authors.forename: D
authors.initials: D
authors.lastname: Elbers
authors.affiliation: , Schmidtkunzstraße 13, 86199, Augsburg, Germany.|Institute for Avian Research "Vogelwarte Helgoland", 26386, Wilhelmshaven, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Bulte
authors.affiliation: Institute for Avian Research "Vogelwarte Helgoland", 26386, Wilhelmshaven, Germany.
authors.forename: F
authors.initials: F
authors.lastname: Bairlein
authors.affiliation: AG Animal Navigation, Faculty of Biology/Environmental Sciences, University of Oldenburg, 26111, Oldenburg, Germany.|Research Centre for Neurosensory Sciences, University of Oldenburg, 26111, Oldenburg, Germany.
authors.forename: H
authors.initials: H
authors.lastname: Mouritsen
mesh_terms: D025041:Animal Migration / Q000502:physiology*; D000818:Animals; D001717:Birds / Q000502:physiology*; D008280:Magnetics; D009949:Orientation
keywords: Magnetoreception; Migratory fuelling; Migratory restlessness; Navigation; Orientation