Relevance of visual cues for orientation at familiar sites by homing pigeons: an experiment in a circular arena.

Whether pigeons use visual landmarks for orientation from familiar locations has been a subject of debate. By recording the directional choices of both anosmic and control pigeons while exiting from a circular arena we were able to assess the relevance of olfactory and visual cues for orientation from familiar sites. When the birds could see the surroundings, both anosmic and control pigeons were homeward oriented. When the view of the landscape was prevented by screens that surrounded the arena, the control pigeons exited from the arena approximately in the home direction, while the anosmic pigeons' distribution was not different from random. Our data suggest that olfactory and visual cues play a critical, but interchangeable, role for orientation at familiar sites.