Drivers of nest-site selection by sea turtles in southern Bahia, Brazil

Marine turtles in Brazil face threats like habitat loss, predation by domestic animals, and climate change. Understanding nesting behavior and reproductive success is essential for conservation. This study investigates the nesting patterns, hatchling success, and main disturbances affecting Caretta caretta, Eretmochelys imbricata, and Chelonia mydas on Comandatuba Island, Brazil, a secondary nesting site (beaches with lower intensity of nesting activity). The southern sector of the island was most frequently used for nesting, despite its narrow beach width and high incidence of nest flooding. The central sector had the highest hatchling success. Predation by domestic dogs was a major disturbance, affecting a significant percentage of nests. Beach width was the only variable distinguishing central and southern sectors, influencing nesting site preference. Nesting females may prioritize safety over ideal conditions, suggesting predation risk influences their choice of nesting sites. Nest depth correlated negatively with hatchling body mass, possibly due to factors that were not measured in the study, such as maternal investment in the egg (e.g., egg mass). Rising sea levels also posed risks, inundating nests and increasing hatchling mortality. This study underscores the importance of secondary nesting sites and highlights marine turtles’ vulnerability to human disturbances and climate change.