TY - JOUR
T1 - Experimental evidence for a magnetic sense in Neotropical migrating butterflies (Lepidoptera: Pieridae)
AU - Srygley, Robert B.
AU - Dudley, Robert
AU - Oliveira, Evandro G.
AU - Riveros, Andre J.
N1 - Funding Information:
This research was funded with a grant from the National Geographic Society Committee for Research and Exploration. In addition, R.B.S. was supported by a Senior Postdoctoral Fellowship from the Smithsonian Institution Office of Fellowships and Grants, Washington, DC and the Korean Science and Engineering Foundation supported preparation of the manuscript. E.G.O. was supported by a CNPq Postdoctoral Fellowship. We thank the National Geographic Society and the Smithsonian Tropical Research Institute for their continued support. We also thank Alejandro Almanza and Ana Portugal for recording behaviour of butterflies in the electromagnet.
PY - 2006/1
Y1 - 2006/1
N2 - We tested whether migrating Aphrissa statira butterflies orient with a magnetic compass. We captured migrants flying over Lake Gatún, Panama, and exposed experimental butterflies to a strong magnetic field. These and unmanipulated control butterflies were released back over the lake. Experimental butterflies had a more dispersed pattern of orientation than control butterflies. The average direction adopted was northeast, 160° anticlockwise to the natural migratory direction. Unmanipulated control butterflies adopted two diametrically opposed orientations: one shifted 33° clockwise, and another 147° anticlockwise, to the migratory direction. Control and experimental butterflies differed in that some controls oriented towards the migratory direction. These differences in orientation support the hypothesis of a sense for magnetic orientation cues. Unmanipulated butterflies released over the lake when the sky was completely overcast were significantly oriented towards their direction before capture (187° and 203°, respectively), further supporting the magnetic compass hypothesis. In a third experiment, we obstructed sun compass cues and reversed the horizontal component of the local geomagnetic field to position magnetic north towards the geographical south pole within a flight arena into which we released individual butterflies. Experimental butterflies experiencing the reversed magnetic field oriented on average 180° opposite to their natural migratory direction. Control butterflies, for which the position of magnetic north was unaltered, were oriented both towards and 180° opposite to the natural migratory direction. This difference between orientations of control and experimental butterflies also supports the hypothesis of a sense for magnetic orientation cues.
AB - We tested whether migrating Aphrissa statira butterflies orient with a magnetic compass. We captured migrants flying over Lake Gatún, Panama, and exposed experimental butterflies to a strong magnetic field. These and unmanipulated control butterflies were released back over the lake. Experimental butterflies had a more dispersed pattern of orientation than control butterflies. The average direction adopted was northeast, 160° anticlockwise to the natural migratory direction. Unmanipulated control butterflies adopted two diametrically opposed orientations: one shifted 33° clockwise, and another 147° anticlockwise, to the migratory direction. Control and experimental butterflies differed in that some controls oriented towards the migratory direction. These differences in orientation support the hypothesis of a sense for magnetic orientation cues. Unmanipulated butterflies released over the lake when the sky was completely overcast were significantly oriented towards their direction before capture (187° and 203°, respectively), further supporting the magnetic compass hypothesis. In a third experiment, we obstructed sun compass cues and reversed the horizontal component of the local geomagnetic field to position magnetic north towards the geographical south pole within a flight arena into which we released individual butterflies. Experimental butterflies experiencing the reversed magnetic field oriented on average 180° opposite to their natural migratory direction. Control butterflies, for which the position of magnetic north was unaltered, were oriented both towards and 180° opposite to the natural migratory direction. This difference between orientations of control and experimental butterflies also supports the hypothesis of a sense for magnetic orientation cues.
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U2 - 10.1016/j.anbehav.2005.04.013
DO - 10.1016/j.anbehav.2005.04.013
M3 - Article
AN - SCOPUS:29444446537
SN - 0003-3472
VL - 71
SP - 183
EP - 191
JO - Animal Behaviour
JF - Animal Behaviour
IS - 1
ER -