First published online October 7, 2008
Journal of Experimental Biology 211, 3344-3350 (2008)
Published by The Company of Biologists 2008
doi: 10.1242/jeb.020313
Light-dependent magnetoreception: orientation behaviour of migratory birds under dim red light
Roswitha Wiltschko1,
Ursula Munro2,
Hugh Ford3,
Katrin Stapput1,* and
Wolfgang Wiltschko1,
1 Fachbereich Biowissenschaften der J. W. Goethe-Universität,
Siesmayerstrasse 70, D-60054 Frankfurt am Main, Germany
2 Department of Environmental Sciences, University of Technology, Sydney, PO Box
123, Broadway, NSW 2007, Australia
3 Division of Zoology, University of New England, Armidale, NSW 2351,
Australia
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Fig. 1. Orientation of Australian silvereyes in the geomagnetic field under green
and red light. Under 565 nm Green (G), which served as control condition, the
birds preferred their seasonally appropriate southerly migratory direction;
under dim 645 nm Red, their response depended on the intensity of light: at 1
mW m–2 (R1), they preferred westerly headings, but
when the light intensity was increased to 2 mW m–2
(R2) and 2.7 mW m–2 (R2.7), the
headings became increasingly diffuse up to random [data at 2.7 mW
m–2 redrawn, with permission, from Wiltschko, W. et al.
(Wiltschko, W. et al., 1993 )
and included for comparison]. The triangles at the periphery of the circle
mark the mean headings of the individual test birds; the arrows represent the
grand mean vector, and the two inner circles are the 5% (broken) and the 1%
(unbroken) significance border of the Rayleigh test.
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Fig. 2. Orientation of Australian silvereyes under dim red light and various
magnetic conditions, indicating a polar response to the magnetic field: left,
tests in the local geomagnetic field (R1); centre, test in a field
with the vertical component inverted (R1vi); right, tests in a
field with the horizontal component shifted 90 deg. counter-clockwise to 270
deg.W (R1h). The corresponding control data under green light are
given in Fig. 1, upper left
diagram. The triangles at the periphery of the circle mark the mean headings
of the individual test birds; the arrows represent the grand mean vector, and
the two inner circles are the 5% (broken) and the 1% (unbroken) significance
border of the Rayleigh test.
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Fig. 3. Orientation of Australian silvereyes under Green (G) and dim red light
(R1) in the local geomagnetic field untreated and with their upper
beak locally anaesthetised with Xylocain (GXy and R1Xy).
The data show that the compass response in migratory direction under green is
not affected by Xylocain, whereas the westerly tendency under dim red light is
disrupted. Lower right diagram: orientation in total darkness (D); the open
arrowheads indicate data points based on one recording only. The triangles at
the periphery of the circle mark the mean headings of the individual test
birds; the arrows represent the grand mean vector, and the two inner circles
are the 5% (broken) and the 1% (unbroken) significance border of the Rayleigh
test.
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Fig. 4. Orientation of European robins in the local geomagnetic field under green
(G, control) light, dim red light (R1) and in total darkness (D).
The triangles at the periphery of the circle mark the mean headings of the
individual test birds; the arrows represent the grand mean vector, and the two
inner circles are the 5% (broken) and the 1% (unbroken) significance border of
the Rayleigh test.
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© The Company of Biologists Ltd 2008
