Predicting leatherback sea turtle sex ratios using spatial interpolation of nesting beach temperatures

Sex determination in leatherback sea turtles is directed primarily by the temperatures a
clutch experiences during the middle third of development. Warmer temperatures tend to produce females will cooler temperatures yield males. Nest temperatures can vary
spatially and temporally. During the 2010 and 2011 nesting seasons, this study estimated the hatchling sex ratio of leatherback sea turtles on Sandy Point National Wildlife Refuge (SPNWR), St. Croix, U.S. Virgin Islands. I measured sand temperatures from May- August and across the spatial range of leatherback nesting habitat. I spatially interpolated those temperatures to create maps that predicted temperatures for all nests incubating on SPWNR. Nest temperatures were also directly measured and compared with predicted nest temperatures to validate the prediction model. Sexes of dead-in-nest hatchlings and full term embryos were used to confirm the sex-temperature response. The model showed that microclimatic variation likely impacts the production of both sexes on SPNWR.