title: Polarized skylight does not calibrate the compass system of a migratory bat.
abstract: In a recent study, Greif et al. (Greif et al. Nat Commun 5, 4488. (doi:10.1038/ncomms5488)) demonstrated a functional role of polarized light for a bat species confronted with a homing task. These non-migratory bats appeared to calibrate their magnetic compass by using polarized skylight at dusk, yet it is unknown if migratory bats also use these cues for calibration. During autumn migration, we equipped Nathusius' bats, Pipistrellus nathusii, with radio transmitters and tested if experimental animals exposed during dusk to a 90° rotated band of polarized light would head in a different direction compared with control animals. After release, bats of both groups continued their journey in the same direction. This observation argues against the use of a polarization-calibrated magnetic compass by this migratory bat and questions that the ability of using polarized light for navigation is a consistent feature in bats. This finding matches with observations in some passerine birds that used polarized light for calibration of their magnetic compass before but not during migration.
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Evolutionary Ecology Research Group, Alfred-Kowalke-Str. 17, Berlin 10315, Germany Department Animal Behaviour, Freie Universität Berlin, Takustr. 3, Berlin 14195, Germany lindecke@izw-berlin.de.
authors.forename: Oliver
authors.initials: O
authors.lastname: Lindecke
authors.affiliation: Leibniz Institute for Zoo and Wildlife Research, Evolutionary Ecology Research Group, Alfred-Kowalke-Str. 17, Berlin 10315, Germany Department Animal Behaviour, Freie Universität Berlin, Takustr. 3, Berlin 14195, Germany.
authors.forename: Christian C
authors.initials: CC
authors.lastname: Voigt
authors.affiliation: Faculty of Veterinary Medicine, Latvia University of Agriculture, K. Helmaņa 8, Jelgava 3004, Latvia.
authors.forename: Gunārs
authors.initials: G
authors.lastname: Pētersons
authors.affiliation: School of Biological Sciences, Queen's University Belfast, Belfast BT9 7BL, UK.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Holland
mesh_terms: D025041:Animal Migration; D000818:Animals; D002685:Chiroptera / Q000502:physiology*; D003463:Cues; D005426:Flight, Animal; D008027:Light; D060526:Magnetic Fields; D009949:Orientation / Q000502:physiology*
keywords: Chiroptera; mammalian navigation; migration; orientation; sensory ecology