Pigeon Homing: The Effect of Temporary Anosmia on Orientation Behavior

Carrier pigeons, Columba livia, re Leased at unfamiliar sites, do not depart randomly, but fly in directions that are normally not far from the homeward course. This indicates that the birds are aware in what direction their ‘home’ lies, and leads to the question: how do the birds know? Avian orientation has been the subject of intensive research during the last few decades, and some parts of this question can already be answered. Navigation is commonly described as a two-step process: In the first step, the map step, the birds determine their home direction as a compass course, and in the second step, they locate this course with the help of a compass and fly in the respective direction. The second step, the compass step, is rather well understood: Pigeons preferentially use a time-compensating sun compass which is, under overcast, backed up by a magnetic compass. The nature of the map step, however, is still largely unknown.