La Tour du Valat

Institut de recherche pour la conservation des zones humides méditerranéennes

Titre :	Orientation by passerine birds under conflicting magnetic and stellar conditions: no calibration in relation to the magnetic field
Auteurs :	Jorgen Rabol, Auteur
Type de document :	Article
Dans :	Dansk Ornitologisk Forenings Tidsskrift (104(3) 2010)
Article en page(s) :	85-102
Langues:	Anglais
Résumé :	Three samples of long-distance passerine juvenile night-migrants were trapped as passage migrants on Christianso in the Baltic Sea in autumn and transported about 300 km W to Endelave, where funnel-experiments under a starry sky were carried out during the following nights. All the time the birds were caged outdoors and able to view the day and night sky and (at least partly) the surroundings down to the horizon. Some of the birds (the experimentals) were caged within a magnetic field where resultant magnetic N was deflected towards geographical E or W. The inclination and intensity of the resultant magnetic field were as those of the Earth's magnetic field. The purpose of the experiments was to find out whether the magnetic compass in the sunset/early night period calibrated the stellar compass for the rest of the night. Such a calibration was not found to occur, but sometimes the magnetic compass of the experimentals acted as the dominant compass during night when the birds were tested within the deflected magnetic fields. Surprisingly, in those cases the orientation was approximately reversed compared with the standard direction.

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