ESTES, J.M.*; WIBBELS, T.; HILLIS-STARR, Z.; PHILLIPS, B.; University of Alabama at Birmingham; University of Alabama at Birmingham; National Park Service: Influence of weather and nest location on hatchling sex ratios of hawksbill sea turtles at Buck Island Reef National Monument, U.S. Virgin Islands

The hawksbill sea turtle, Erethmochelys imbricata, possesses temperature-dependent sex determination (TSD) in which the incubation temperature of the egg determines the sex of the hatchling. This form of sex determination has the potential of producing a wide variety of sex ratios. Therefore the sex ratios are of ecological, evolutionary and conservation interest. Buck Island Reef National Monument (located approximately 2 km north of St. Croix) represents a natural and undeveloped nesting beach for the endangered hawksbill sea turtle in the Caribbean. The purpose of the current study was to monitor hatchling sex ratios of hawksbill sea turtles produced on Buck Island during the 1997, 1998, and 1999 nesting seasons. Temperature data loggers were used to monitor incubation temperatures in nests and to monitor beach temperatures. Incubation temperature during the middle third of the incubation period was used to predict hatchling sex ratios. The results suggest an overall female bias during each of the three nesting seasons. However, the results also suggest that some male-biased clutches were produced in response to temperature decreases associated with tropical weather systems passing through the study area.