ESTES, J.M.; WIBBELS, T.; HILLIS-STARR, Z.; PHILLIPS, B.; MAYOR, P.; University of Alabama at Birmingham; University of Alabama at Birmingham; National Park Service, St. Croix, U.S.V.I.; National Park Service, St. Croix, U.S.V.I.; National Park Service, St. Croix, U.S.V.I.: Multi-year Evaluation of Hatchling Sex Ratios of Hawksbill Turtles from a Caribbean Rookery

The hawksbill sea turtle possesses temperature-dependent sex determination (TSD), which has the potential of producing a wide variety of sex ratios. Therefore, the sex ratios are of ecological, evolutionary, and conservational interest. Buck Island Reef National Monument (located approximately 2 km north of St. Croix) represents a natural and undeveloped nesting beach for endangered hawksbill sea turtles 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 1995-1999, and 2002 nesting seasons. Temperature data loggers were placed into the center of the egg mass in each nest. Data loggers were also placed in beach locations at midnest depth to monitor beach temperatures. Sex ratio predictions were based on the average temperature during the middle third of incubation. The results suggest that a variety of sex ratios were produced on Buck Island (ranging from all female to all male), but overall, a significant female bias was predicted in each of the six seasons examined. 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 and by nest location.