Migration behavior of loggerhead turtle measured by datatags.

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Migration behavior of loggerhead turtles was recorded using microdata tags during internesting. A tag was able to record diving depth and duration, experienced water temperatures, stomach temperatures and underwater irradiance during internesting periods while the turtles swam around the nesting beach. The data were analyzed after tags recovery from the turtles. We could find that turtles neither ate food nor swam off the beach during internesting periods, which were analyzed by means of the diving records and tracking trajectries of ARGOS system. They maintained always higher body temperatures than ambient water temperatures. Underwater irradiance and water temperature records indicated that they did not accept effective heat supply from the solar irradiance energy to maintain high body temperatures. The phenomenon to keep high body temperature was able to analyze using mathematical dynamic heat transfer model with two parameters ; an heat diffusivity and a body mass. We could find the critical sex determination period of newly hatched out turtles. The temperature dependent sex was determined in the period between 23 to 26 developmental stage of eggs.