White-throated sparrows calibrate their magnetic compass by polarized light cues during both autumn and spring migration

SUMMARY The interaction and hierarchy of celestial and magnetic compass cues used by migratory songbirds for orientation has long been the topic of an intense debate. We have previously shown that migratory Savannah sparrows, Passerculus sandwichensis, use polarized light cues near the horizon at sunrise and sunset to recalibrate their magnetic compass. Birds exposed to a ±90 deg. shifted artificial polarization pattern at sunrise or sunset recalibrated their magnetic compass, but only when given full access to celestial cues, including polarized light cues near the horizon. In the current study, we carried out cue conflict experiments with white-throated sparrows, Zonotrichia albicollis, during both spring and autumn migration in a transition zone between the species' breeding and wintering areas on the south shore of Lake Ontario. We show that white-throated sparrows also recalibrate their magnetic compass by polarized light cues at sunrise and sunset. Sunrise exposure to an artificial polarization pattern shifted relative to the natural magnetic field or exposure to a shift of the magnetic field relative to the natural sky both led to recalibration of the magnetic compass, demonstrating that artificial polarizing filters do not create an anomalous, unnatural orientation response. Our results further indicate that there is no evidence for a difference in compass hierarchy between different phases of migration, confirming previous work showing that polarized light cues near the horizon at sunrise and sunset provide the primary calibration reference both in the beginning and at the end of migration.

[1]  M. D.,et al.  Sun Compass , 1945, Nature.

[2]  C. W. Helms,et al.  Winter and Migratory Weight and Fat Field Studies on Some North American Buntings , 1960 .

[3]  Stephen T. Emlen,et al.  A TECHNIQUE FOR RECORDING MIGRATORY ORIENTATION OF CAPTIVE BIRDS , 1966 .

[4]  W. Wiltschko,et al.  Magnetic Compass of European Robins , 1972, Science.

[5]  S. Emlen.  The stellar-orientation system of a migratory bird. , 1975, Scientific American.

[6]  M. Brines,et al.  Dynamic patterns of skylight polarization as clock and compass. , 1980, Journal of theoretical biology.

[7]  J. L. Gould,et al.  Skylight Polarization patterns and Animal Orientation , 1982 .

[8]  K. Able.  Skylight polarization patterns at dusk influence migratory orientation in birds , 1982, Nature.

[9]  B. Heller.  Circular Statistics in Biology, Edward Batschelet. Academic Press, London & New York (1981), 371, Price $69.50 , 1983 .

[10]  V. Bingman.  Magnetic Field Orientation of Migratory Savannah Sparrows With Different First Summer Experience , 1983 .

[11]  F. Moore.  Sunrise, skylight polarization, and the early morning orientation of night-migrating warblers , 1986 .

[12]  Péter,et al.  Identification Guide To North American Passerines: A Compendium Of Information On Identifying, Ageing, And Sexing Passerines In The Hand , 1987 .

[13]  F. Moore.  SUNSET AND THE ORIENTATION BEHAVIOUR OF MIGRATING BIRDS , 1987 .

[14]  F. Moore,et al.  Sunset, skylight polarization and the migratory orientation of yellow-rumped warblers, Dendroica coronata , 1988, Animal Behaviour.

[15]  K. Able,et al.  Ontogeny of migratory orientation in the savannah sparrow, Passerculus sandwichensis: calibration of the magnetic compass , 1990, Animal Behaviour.

[16]  W. Wiltschko,et al.  Migratory orientation of pied flycatchers: interaction of stellar and magnetic information during ontogeny , 1992, Animal Behaviour.

[17]  Kenneth P. Able,et al.  Daytime calibration of magnetic orientation in a migratory bird requires a view of skylight polarization , 1993, Nature.

[18]  K. Able,et al.  Interactions in the flexible orientation system of a migratory bird , 1995, Nature.

[19]  K. Able,et al.  Development of sunset orientation in a migratory bird: no calibration by the magnetic field , 1997, Animal Behaviour.

[20]  K. Able,et al.  Manipulations of polarized skylight calibrate magnetic orientation in a migratory bird , 1995, Journal of Comparative Physiology A.

[21]  W. Cochran,et al.  Migrating Songbirds Recalibrate Their Magnetic Compass Daily from Twilight Cues , 2004, Science.

[22]  V. Bingman.  Night sky orientation of migratory pied flycatchers raised in different magnetic fields , 1984, Behavioral Ecology and Sociobiology.

[23]  S. Åkesson,et al.  Polarized Light Cues Underlie Compass Calibration in Migratory Songbirds , 2006, Science.

[24]  Birgit Greiner,et al.  Celestial polarization patterns during twilight. , 2006, Applied optics.

[25]  F. Moore,et al.  Calibration of magnetic and celestial compass cues in migratory birds - a review of cue-conflict experiments , 2006, Journal of Experimental Biology.

[26]  S. Åkesson,et al.  Magnetic compass of migratory Savannah sparrows is calibrated by skylight polarization at sunrise and sunset , 2007, Journal of Ornithology.

[27]  S. Åkesson,et al.  Response to R. Wiltschko et al. (J. Ornithol.): Contradictory results on the role of polarized light in compass calibration in migratory songbirds , 2008, Journal of Ornithology.

[28]  Wolfgang Wiltschko,et al.  Contradictory results on the role of polarized light in compass calibration in migratory songbirds , 2008, Journal of Ornithology.

[29]  R. Muheim,et al.  Fuel reserves affect migratory orientation of thrushes and sparrows both before and after crossing an ecological barrier near their breeding grounds , 2009 .

[30]  H. Wagner,et al.  Die Sternenorientierung nächtlich ziehender Grasmücken (Sylvia atricapilla, borin und curruca)1 , 2010 .