INDEPENDENT VERSUS SOCIALLY FACILITATED OCEANIC MIGRATIONS OF THE OLIVE RIDLEY, LEPIDOCHELYS OLIVACEA

Sea turtles migrate between feeding and nesting areas that are often g eographically separated by hundreds or thousands of kilometers. Observ ations of their aggregations at sea and at nesting beaches have led to the hypothesis that sea turtles migrate in socially structured groups . While this migratory strategy is common to many marine vertebrates, socially facilitated behavior is not well documented in testudines. In 1990 and 1991, we attached satellite transmitters to olive ridleys (L epidochelys olivacea Eschscholtz) found ovipositing together during a mass nesting at Nancite Beach, Costa Rica, to determine whether they m igrate independently or in groups after they leave the nesting beach. Results showed that the turtles were not spatially associated during t he internesting period, were capable of re-establishing themselves as a group during a subsequent nesting emergence, and were not spatially associated during their postnesting migrations to oceanic feeding area s. We suggested that what appear to be socially structured groups of L . olivacea are in fact individual turtles simultaneously using the sam e habitat.