Detour experiments with homing pigeons: information obtained during the outward journey is included in the navigational process

Summary To test the hypothesis that information on the route of the outward journey is involved in the orientation of displaced homing pigeons, we compared the behavior of control pigeons that had been displaced by the most direct route with that of experimental pigeons that had been transported along detours to the same release sites. At distances of 40 km we found no consistent effect. At distances between 75 and 130 km, however, deviations to the left of the direct route induced deflections to the left, while deviations to the right induced deflections to the right, i.e. the deflections of the vanishing bearings tended to compensate for the initial detour of the outward journey. The deflections were smaller than the deviations of the routes; they were not related to the routes themselves or the location of the release sites. A significant correlation emerged with the vector length of the controls, as longer vectors were associated with smaller deflections. This suggests that information on the route of the outward journey is used together with local map information in the navigational process, the significance of the route-specific information apparently depending on quality and reliability of the available local information. The nature of factors controlling the detour effect is still open.Correspondence to: R. Wiltschko