Fig. 3. Orientation of young pied flycatchers held in captivity during the time of their first migration. Results are shown from birds maintained in the magnetic field of Frankfurt, Germany (left), and birds subjected to a sequence of magnetic fields approximately matching those that they encounter along the migratory pathway (right). During the time corresponding to the first leg of the migration (Leg 1), both groups of birds were significantly oriented toward the south-southwest, corresponding with the direction that they initially travel. Only the birds exposed to the magnetically simulated migration, however, adopted appropriate southeasterly orientation during the time corresponding to the second leg of the migration (Leg 2). The arrow in the center of each circle represents the mean angle of the group. Arrows that extend across the first inner circle (dotted line) denote distributions that are significantly oriented at P<0.05, whereas those that extend across the second inner circle (solid line) denote P<0.01. (Modified from Beck and Wiltschko, 1988; Wiltschko and Wiltschko, 2005.)