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Magnetic compass of migratory Savannah sparrows is calibrated by skylight polarizarion and sunrise and sunset

Muheim, Rachel LU ; Åkesson, Susanne LU and Phillips, John (2007) In Journal für Ornithologie1852-12-31+01:002004-01-01+01:00 148(Supplement 2). p.485-494
Abstract
Migratory birds use compass systems derived from the geomagnetic field, the stars, the sun and polarized light patterns. We tested whether birds use a single underlying reference system for calibration of these compasses and, specifically, whether sunset and sunrise polarized light cues from the region of the sky near the horizon are used to calibrate the magnetic compass. We carried out orientation experiments with Savannah sparrows, Passerculus sandwichensis, in Alaska during autumn migration 2005, and compared the magnetic orientations of individual birds before and after exposure to conflicting information between magnetic and celestial cues. Birds exposed to an artificially shifted polarization pattern (±90° shift relative to the... (More)
Migratory birds use compass systems derived from the geomagnetic field, the stars, the sun and polarized light patterns. We tested whether birds use a single underlying reference system for calibration of these compasses and, specifically, whether sunset and sunrise polarized light cues from the region of the sky near the horizon are used to calibrate the magnetic compass. We carried out orientation experiments with Savannah sparrows, Passerculus sandwichensis, in Alaska during autumn migration 2005, and compared the magnetic orientations of individual birds before and after exposure to conflicting information between magnetic and celestial cues. Birds exposed to an artificially shifted polarization pattern (±90° shift relative to the natural condition) for 1 h at local sunrise or sunset recalibrated their magnetic compass, but only when given access to the artificial polarization pattern near the horizon. Birds exposed to a 90° clockwise-shifted magnetic field for 1 h at solar noon did not recalibrate their magnetic compass. These results indicate that migratory birds calibrate their magnetic compass using the skylight polarization pattern vertically intersecting the horizon at sunrise and sunset. In conjunction with earlier work showing that sun and star compass calibrations are secondarily derived from magnetic and polarized light cues, our findings suggest that polarized light cues near the horizon at sunrise and sunset provide the primary calibration reference for the compass systems of migratory songbirds. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Orientation - Cue calibration - Magnetic compass - Skylight polarization
in
Journal für Ornithologie1852-12-31+01:002004-01-01+01:00
volume
148
issue
Supplement 2
pages
485 - 494
publisher
Springer
external identifiers
  • wos:000255199000042
  • scopus:36949028098
ISSN
1439-0361
DOI
10.1007/s10336-007-0187-4
language
English
LU publication?
yes
id
232bb9b6-c3f7-4e28-988d-7f13610c74bc (old id 788008)
date added to LUP
2008-01-02 19:21:29
date last changed
2017-10-22 03:47:15
@article{232bb9b6-c3f7-4e28-988d-7f13610c74bc,
  abstract     = {Migratory birds use compass systems derived from the geomagnetic field, the stars, the sun and polarized light patterns. We tested whether birds use a single underlying reference system for calibration of these compasses and, specifically, whether sunset and sunrise polarized light cues from the region of the sky near the horizon are used to calibrate the magnetic compass. We carried out orientation experiments with Savannah sparrows, Passerculus sandwichensis, in Alaska during autumn migration 2005, and compared the magnetic orientations of individual birds before and after exposure to conflicting information between magnetic and celestial cues. Birds exposed to an artificially shifted polarization pattern (±90° shift relative to the natural condition) for 1 h at local sunrise or sunset recalibrated their magnetic compass, but only when given access to the artificial polarization pattern near the horizon. Birds exposed to a 90° clockwise-shifted magnetic field for 1 h at solar noon did not recalibrate their magnetic compass. These results indicate that migratory birds calibrate their magnetic compass using the skylight polarization pattern vertically intersecting the horizon at sunrise and sunset. In conjunction with earlier work showing that sun and star compass calibrations are secondarily derived from magnetic and polarized light cues, our findings suggest that polarized light cues near the horizon at sunrise and sunset provide the primary calibration reference for the compass systems of migratory songbirds.},
  author       = {Muheim, Rachel and Åkesson, Susanne and Phillips, John},
  issn         = {1439-0361},
  keyword      = {Orientation - Cue calibration - Magnetic compass - Skylight polarization},
  language     = {eng},
  number       = {Supplement 2},
  pages        = {485--494},
  publisher    = {Springer},
  series       = {Journal für Ornithologie1852-12-31+01:002004-01-01+01:00},
  title        = {Magnetic compass of migratory Savannah sparrows is calibrated by skylight polarizarion and sunrise and sunset},
  url          = {http://dx.doi.org/10.1007/s10336-007-0187-4},
  volume       = {148},
  year         = {2007},
}