Towards the map of the homing pigeon?

Abstract

The behaviour of pigeons, Columba liva, homing from different sites was used to generate a geographical map based on empirical data. With the help of cluster analysis, release sites were grouped into clusters of sites according to similarities in the initial orientation of the pigeons when released. These similarities in initial orientation were assumed to reflect similarities in the information of the map component. The initial orientation of samples of pigeons was characterized by the length of the mean vector and the angular deviation of the mean vanishing direction from the home direction. According to this analysis the map information is distributed in distinct patches extending over several tens of kilometres. Exposing pigeons to air collected within one of these patches but releasing them after anaesthesia of their olfactory mucosae at a site opposite to the home loft within a different patch resulted in disorientation. This experiment, however, yielded significant differences between control and experimental pigeons within only two out of four distinct patches. This suggests that the map has an airborne component. Parts of the map, however, are based on other physical cues. How these ‘landmarks’ could be used for navigation even when the perception of one or the other component has been eliminated is discussed.