A New Technique to Monitor the Flight Paths of Birds

The study of the mechanisms which govern bird orientation and navigation is severely hindered by the difficulty of reconstructing the route taken by the bird. Several methods have been used to study bird flights: direct observation using binoculars; following the bird by aeroplane or helicopter (Griffin, 1943; Hitchcock, 1952; Fiaschi, Baldaccini, loalè & Papi, 1981); using a transmitter carried by the bird (Michener & Walcott, 1966; Schmidt-Koenig & Walcott, 1978); and location of the bird using radar techniques (Eastwood, 1967; Papi & Pardi, 1978). All these techniques require that the bird and the monitoring equipment always be within optical or electromagnetic ‘visibility’.