International Programs

Sea turtles are endangered species that can be censused with aerial surveys, but the number of turtles in an area must be extrapolated to include animals that are submerged. Twenty-one satellite tags were attached to juvenile loggerhead sea turtles (Caretta caretta) in North
Carolina. I analyzed surfacing and dive behavior recorded by the tags to determine whether time of day, time of year, location or wave height were important factors for development of more accurate population estimates in aerial surveys. I also analyzed differences in percent time at the surface based on a tag's salt water switch and its depth gauge. I found significantly greater surfacing during the day during April-June for two turtles and greater surfacing during the night during October-December for four turtles. Turtles in offshore habitats surfaced more often than those in inshore and nearshore habitats. Only one turtle that experienced wave heights greater than 2.5m showed a negative correlation between surfacing and wave height.
The depth gauge consistently recorded an order of magnitude greater percent time near the surface than the salt water switch, and overall trends in behavior were different, suggesting the salt water switch is inadequate for recording surfacing events for aerial survey extrapolations.