Reptilian diving: highly variable dive patterns in the green turtle Chelonia mydas

Diving reptiles,unlike most diving birds and mammals, return infrequently t o the surface to breathe. spending the bulk of their lives underwater, they are likely to have developed a large variety of specific behavioural patte rns different from those of their warm-blooded counterparts. However, for t echnical reasons, underwater behaviour of these aquatic reptiles remains po orly understood. In this study green turtles Chelonia mydas nesting on Cypr us (Eastern Mediterranean) were equipped with multi-channel data loggers mo nitoring diving behaviour and activity (via a logger-integrated 3-D compass which served as an activity sensor) during the inter-nesting interval. Dat a from 2 turtles for 2 consecutive inter-nesting intervals were available f or detailed dive analysis. Both turtles showed highly variable dive pattern s ranging from travelling subsurface dives to specific dive types such as U - (mainly resting and foraging dives), S- (a form of energy saving swimming ) and V-dives. The green turtles stayed near the coast throughout the study , dived no deeper than ca 25 m, but remained underwater for up to ca 40 min . The recordings of the activity sensor revealed high activity levels (less than 20% resting d(-1)) during the whole inter-nesting time spent underwat er, foraged for 34% and rested for 12% of the time. We discuss the physiolo gical. ecological and conservation implications of these results.