Abstract

Hatchling marine turtles emerge at night from underground nests, enter the ocean, and swim offshore. Here, we measured the intensity (hours swimming) and the temporal patterning (diurnal vs. nocturnal expression) of activity shown by Malaysian (Sulu Sea) hawksbill (Eretmochelys imbricata) and green turtle (Chelonia mydas) hatchlings tethered inside pools for six days, postemergence. The results were compared to the activity shown during the same period of development by sea turtles in Florida. The two species from Malaysia showed significant differences in activity both from one another and from the Florida (leatherback, Dermochelys coriacea; loggerhead, Caretta caretta; and green turtle) species. Hawksbills were less active than the hatchlings from Florida, swimming on average < 6 h/d. Hawksbills did not show a frenzy period of hyperactive swimming, typical of the first day of offshore migration by the hatchlings from Florida. Green turtles swam on average about 17 h each day during a two-day frenzy period that was one day longer than the frenzy period shown by green turtles from Florida; thereafter, activity showed a significant decline. These results suggest the two species use different strategies to avoid predators near shore. Hawksbills may hide in flotsam or remain inactive to minimize detection; whereas, green turtles may reduce their exposure time by rapid locomotion through shallow water. We conclude that the frenzy period shown by hatchlings during offshore migration is a variable trait both among marine turtle species and between green turtle populations nesting on Western Atlantic and Sulu Sea beaches.

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