Effects of Diving and Swimming Behavior on Body Temperatures of Pacific Leatherback Turtles in Tropical Seas

Mathematical models and recordings of cloacal temperature suggest that leatherback turtles (Dermochelys coriacea) maintain core body temperature higher than ambient water temperature (TW) while freely swimming at sea. We investigated the thermoregulatory capabilities of free‐ranging leatherbacks and, specifically, the effect that changes in diving patterns and ambient temperatures have on leatherback body temperatures (TB). Data loggers were used to record subcarapace and gastrointestinal tract temperatures (TSC and TGT, respectively), TW, swim speed, dive depth, and dive times of female leatherback turtles during internesting intervals off the coast of Guanacaste, Costa Rica. Mean TSC (28.7°–29.0°C) was significantly higher than mean TW (25.0°–27.5°C). There was a significant positive relationship between TSC and TW and a significant negative correlation between TSC and dive depth and TGT and dive depth. Rapid fluctuations in TGT occurred during the first several days of the internesting interval, which suggests that turtles were ingesting prey or water during this time. Turtles spent 79%–91% of the time at sea swimming at speeds greater than 0.2 m s−1, and the average swim speed was m s−1. Results from this study show that alterations in diving behavior and TW affect TB of leatherback turtles in the tropics. Body temperatures of free‐ranging leatherback turtles correspond well with values for TB predicted by mathematical models for tropical conditions