Flight recorders: A technique for the study of bird navigation

Abstract

IN experiments on the homing ability of birds, it would obviously be a great advantage if one knew the actual time spent in flying by a bird which had been released some way from home and which had returned after a known time. Mere knowledge of the time between release and return can only provide an upper limit for the effort expended by the bird in regaining home : in practice, the real flying time may be very much less than this, and knowledge of it is vital in deciding for or against hypotheses involving search or some real navigational ability. Following the bird by light aeroplane has been accomplished 1 : this technique, though very powerful, is cumbersome and cannot cope with a homing flight of some days. Exner2 has used a method dependent on the different rates of evaporation of camphor in still and moving air to measure the flying time, but this method is susceptible of only very limited accuracy; nevertheless it constitutes the first, and very early, attempt to measure the flying time. © 1950 Nature Publishing Group.