Two hypotheses on magnetoreception in animals are currently discussed. The first hypothesis is based on light-dependent processes associated with the visual system, while the second hypothesis suggests that magnetoreception is based on biogenic magnetite. Both mechanisms are supported by experimental evidence, but whether the information they provide involves the magnetic compass or the ‘map’ is still open. In order to identify the relevance of light-dependent or magnetite-transduced processes in magnetoreception, juvenile migratory birds were tested for their orientation behaviour in the natural geomagnetic field as the only directional cue available to them. The test birds were juvenile Tasmanian silvereyes (Zosterops l. lateralis), which were caught on their native island soon after fledging, before they had an opportunity to establish a navigational ‘map’. (1) Under ‘white’ (full spectrum) and green light (571 nm), they were well oriented in their appropriate migratory direction, while they were disoriented under red light (633 nm). This coincides with previous findings on adult silvereyes and suggests that light-dependent processes are involved in an orientation mechanism used by both juvenile and adult migrants, namely the magnetic compass. (2) A short, high-intensity magnetic pulse, a treatment designed to alter the magnetisation of magnetite, did not affect the young birds´ orientation. They continued to select their seasonally appropriate migratory direction. In contrast, adult silvereyes from the same population had responded in a previous study with a 90° clockwise deflection from their normal migratory course. These results suggest that (a) magnetite is involved in an orientation mechanism used exclusively by adult migrants; and (b) a magnetite-based receptor is associated with the navigational ‘map’, which provides information on geographic position.

The Yellow‐faced Honeyeater Lichenostomus chrysops is a diurnal migrant which covers short to moderate distances in eastern Australia. Recordings of locomotor activity of nine wild‐caught Yellow‐faced Honeyeaters kept under a simulated natural photoperiod in the laboratory over a period of 13 months showed that these birds exhibit a distinct seasonal pattern in hopping activity. Two major seasonal peaks of enhanced activity were observed. The first occurred during the time of autumn migration in March to July, while a second peak from September to December coincided roughly with spring migration. Daily activity patterns of Yellow‐faced Honeyeaters showed two major peaks. The first peak ranged from the early morning hours to approximately early afternoon, while a second smaller peak was observed in the late afternoon. During their migratory periods in spring and autumn, the morning as well as the afternoon peaks were considerably higher than in months when Yellow‐faced Honeyeaters do not migrate.