Spatial and feature-based memory representation in free-flying homing pigeons.

The memory-based recognition of a goal is a capacity well demonstrated in birds, and understanding this ability often involves determining the relative importance of spatial and feature information in representing the properties of a goal. However, surprisingly little avian research has examined goal recognition in a field setting. Here, we demonstrate that homing pigeons can be successfully trained outdoors to fly to and land on a goal platform located in an array of other platforms at a distance on the order of 100 m. They can do so under conditions when the properties of the goal are stable in time as well as when the properties of the goal periodically change; the latter condition indicating that homing pigeons can rapidly adapt their memory representations to take into account changing environmental conditions. When probed for preferential use of either spatial (location) or feature-based (color) information, the pigeons demonstrated an indifferent capacity to use both independent of task demands. The homing pigeon memory systems that support goal recognition appear to be opportunistic with respect to the information exploited, using spatial and feature information equally to guide their behavior. Therefore, and despite strong natural and artificial selection for navigational ability, spatial information is no more important than feature cues in representing a goal location for homing pigeons flying outdoors.