A MAGNETIC PULSE LEADS TO A TEMPORARY DEFLECTION IN THE ORIENTATION OF MIGRATORY BIRDS

Migratory Australian Silvereyes were treated with a strong magnetic pu lse designed to alter the magnetization of the small magnetite particl es that are found in birds' heads. Prior to the treatment, the birds p referred the northeasterly migratory direction. The pulse initially re sulted in a 90 degrees clockwise shift of orientation; however, within about a week, the birds seemed to return to their original headings. These findings, which seem to suggest an involvement of magnetite in m igratory orientation, are in contrast with previous findings which ind icated that it is a light-dependent process. They are discussed in vie w of the current concepts on magnetoreception and on the role of magne tic information in avian orientation.