Wiltschko, Wolfgang; Ford, Hugh; Munro, Ursula; Winklhofer, Michael; Wiltschko, Roswitha
Magnetite-based magnetoreception: the effect of repeated pulsing on the orientation of migratory birds.
In: Journal of Comparative Physiology A - Neuroethology, Sensory, Neural, and Behavioral Physiology, Vol. 193, No. 5: pp. 515-522
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Previous studies have shown that a magnetic pulse affected theorientation of passerine migrants for a short period only: for about 3days, the birds’ headings were deflected eastward from their migratorydirection, followed by a phase of disorientation, with the birdsreturning to their normal migratory direction after about 10 days. Toanalyze the processes involved in the fading of the pulse effect,migratory birds were subjected to a second, identical pulse 16 daysafter the first pulse, when the effect of that pulse had disappeared.This second pulse affected the birds’ behavior in a different way: itcaused an increase in the scatter of the birds’ headings for 2 days,after which the birds showed normal migratory orientation again. Theseobservations are at variance with the hypothesis that themagnetite-based receptor had been fully restored, but also with thehypothesis that the input of this receptor was ignored. They ratherindicate dynamic processes, which include changes in the affectedreceptor, but at the same time cause the birds to weigh and rate thealtered input differently. The bearing of these findings on the questionof whether single domains or superparamagnetic particles are involved inthe magnetite-based receptors is discussed.