Foraging and overwintering behavior of loggerhead sea turtles Caretta caretta in the western North Atlantic

Abstract

Discerning the foraging habitat requirements of wildlife is key to providing for their conservation and management, especially with rare species. Sea turtles are slow-growing, late-maturing species that undertake wide-ranging migrations, making them especially susceptible to changes and disruptions in their environment. To protect and successfully manage these imperiled populations, an understanding of their spatial ecology is required; thus, characterizing critical habitats, identifying high-density areas, and identifying foraging regions is essential. We captured 30 loggerhead sea turtles Caretta caretta (male and female; juvenile and adult) in the estuarine waters of North Carolina (USA) and tracked them in western North Atlantic neritic (nearshore and offshore) waters. Using a combination of satellite telemetry and spatial modeling techniques, we characterized their movements and identified foraging and overwintering sites. Average core-use areas in the north had greater net primary production (NPP) and were smaller than those in the south, indicating more abundant marine resources in northern foraging regions. In summer, loggerheads migrated to both northern and southern foraging grounds, but most (53%) resided within North Carolina neritic waters. Likewise, the majority of loggerheads (67%) we tracked in winter remained in North Carolina neritic waters, underscoring the importance of this area as year-round foraging habitat, and lending to its consideration as potential critical habitat for both juvenile and adult loggerheads. The change to foraging behavior mode was significantly influenced by day of the year, geographic location, and NPP; however, individual-specific factors influenced switching probabilities relative to other covariates. Data highlighting ‘hotspots’ or densely used areas by foraging sea turtles can thus be used by conservation managers to make informed decisions concerning sea turtle conservation measures.