LONG-DISTANCE MIGRATION AND HOMING AFTER DISPLACEMENT IN THE GREEN TURTLE (CHELONIA-MYDAS) - A SATELLITE TRACKING STUDY

Four green turtle females were tracked by satellite during their post- reproductive migration in the South China Sea. Three of them reached t heir feeding grounds 923-1551 km distant. During nesting activity, a f emale was displaced twice, and her return trips to the nesting beach f rom 11 and 284 km were tracked by a direction-recording data-logger an d by satellite, respectively. Part of the journeys occurred coastwise, indicating that leading geographical features had been utilised. The straightness of the turtles' tracks in open seas, both over shallow an d deep waters, and their ability to pinpoint distant targets and home after displacement off their usual routes, provides circumstantial evi dence for a true navigation mechanism.