Dear Marman list members, Please find attached to this e-mail a recent publication in *The Journal of Experimental Biology* on thermoregulation in leatherback turtles (*Dermochelys coriacea*). The study presents the first body temperature recordings of freely swimming adult leatherbacks at high latitude foraging grounds off Nova Scotia, Canada. The results provide additional support for endothermy in leatherbacks by highlighting the role of heat produced via visceral organs (i.e. specific dynamic action) for maintenance of a large (>10C) thermal gradient in cold water. The study also found that behavior (i.e. use of warm surface waters) had a significant effect on their body temperatures, while exploiting a seasonally high abundance of prey at high latitudes. *Behavioral and metabolic contributions to thermoregulation in freely swimming leatherback turtles at high latitudes* By James P. Casey, Michael C. James, and Amanda S. Williard Leatherback turtles in the Northwest Atlantic Ocean have a broad geographic range that extends from nesting beaches near the equator to seasonal foraging grounds as far north as Canada. The ability of leatherbacks to maintain core body temperature (Tb) higher than that of the surrounding water is thought to be a key element of their biology that permits them to exploit productive waters at high latitudes. We provide the first recordings of Tb from freely swimming leatherbacks at a northern foraging ground, and use these data to assess the importance of behavioral adjustments and metabolic sources of heat for maintenance of the thermal gradient (Tg). The mean Tb for individual leatherbacks ranged from 25.4±1.7 to 27.3±0.3°C, and Tg ranged from 10.7±2.4 to 12.1±1.7°C. Variation in mean Tb was best explained by the amount of time that turtles spent in the relatively warm surface waters. A diel trend in Tb was apparent, with daytime cooling suggestive of prey ingestion and night-time warming attributable to endogenous heat production. We estimate that metabolic rates necessary to support the observed Tg are ~3 times higher than resting metabolic rate, and that specific dynamic action is an important source of heat for foraging leatherbacks. *The Journal of Experimental Biology* (2014) 217, 2331-2337 doi:10.1242/jeb.100347 Sincerely, James Casey