A NEW EXPERIMENT TO VERIFY THE SPATIAL RANGE OF PIGEONS OLFACTORY MAP

A series of tests with homing pigeons was carried out to verify the sp atial range of their olfactory map. In each test, a group of experimen tal birds, which had been prevented from smelling ambient odours durin g the passive displacement, was compared to a group of controls which always had free access to olfactory information. Our results show that the range of unfamiliar area where pigeons are able to navigate on th e basis of local cues is rather limited (less than 120 km from the hom e loft). Homeward orientation, however, normally occurs beyond the lim its of the olfactory map as the birds are able to use odorous cues per ceived during the initial part of the outward journey. Our results are in agreement with the ''mosaic'' hypothesis of pigeons' olfactory nav igation.