On Bird Navigation, with Some Statistical Undertones

Summary Young migratory birds appear innately programmed to fly for given distances in given directions. The orientations of the circular distributions of their escape attempts from cages, or of vanishing points in free flight, have been subjected to refined statistical analysis recently. Time-compensated sun- and moon-orientations have been demonstrated. Compass directions are also obtained from the alignment of the constellations. Non-astronomical methods of orientation are of secondary importance. Adult birds have the ability to correct for geographical displacement, sometimes over thousands of kilometres. A form of bi-coordinate navigation is probably involved, but the bases of the navigational grid remain uncertain. Pigeons can detect and react to small changes in sun altitude in terms of latitudinal displacement. The sun's position along its arc in relation to time may give longitudinal information. Homeward orientation is not of phenomenal accuracy, leaving open the possibility that random search for the known area plays a part.