SIEG, A/E; SPOTILA, J/R; BINCKLEY, C/A; PALADINO, F/V; Drexel University; Drexel University; Old Dominion; Indiana Purdue, Fort Wayne: Effects of Ambient Temperature and Precipitation on Inferred Sex Ratios for Leatherback Sea Turtle Nests at Playa Grande, Costa Rica

Temperature is an abiotic factor that has been well-documented in its effects on sea turtle nests�especially in determining the sex of hatchlings (TSD; Standora and Spotila, 1985). For leatherback sea turtles (Dermochelys coriacea) nesting at Playa Grande, Costa Rica, only time on a seasonal scale had a significant effect on observed sex ratios. We estimated sex ratios of leatherback hatchlings from Playa Grande using meteorological data (ambient temperature and precipitation per month) collected at stations near the beach from 1949-1996. We also inferred sex ratios of leatherback hatchlings by using nest temperature data recorded from in situ nests from 1997-98 and 2000-01 thru 2002-03. The sex ratio from 1949-1996 was 12.8% male(M): 87.2% female(F). The sex ratio in 1997-98 was 7.9%M: 92.1%F, in 2000-01 it was 0%M: 100%F, in 2001-02 it was 18.2%M: 81.8%F, and in 2002-03 it was 6.5%M: 93.5%F. Female bias occurs in most seasons on Playa Grande, Costa Rica. However, this does not affect fertility of eggs (Bell et al., 2004) or apparent abundance of mating males (Reina, Crittercam).