97 % Female = 105.3481 / (1 + EXP (- (TEMP - 28.5102) / 1.1379)) Where TEMP is the mean temperature for the middle third of the incubation period. The Girondot (1999) model: % Male = 1 / (1 + EXP (1 / S * (P - t))) Where t is the mean temperature over the full incubation period, P is the pivotal temperature and S defines the shape of transition from masculinizing to feminizing temperature. For the purpose of this paper, P and S values of the RP and the GLS areas were estimated using the assessments made for Australian nesting sites, as the nesting females belong to the same genetic stock (Boyle et al. 2009), and based on the habitat similarities. Hence, we have used the P and S values measured on the site of Mon Repos for the RP beach (both exhibiting a coastal, dark-colored beach), and on the site of Heron Island for the GLS area (both exhibiting coral-islet, light-colored beaches) (Table 10 SI Appendix). The Mrosovsky et al. (2002) model, with sex ratio as a function of the temperature % Female = 100.06 / (1 + EXP (188.78 - 6.37 * X)) Where X is the mean temperature for the middle third of the incubation period. The Mrosovsky et al. (2002) model, with sex ratio as a function of the incubation duration % Female = 99.88 / (1 + EXP (-103.34 + 1.82 * X)) Where X is the incubation duration. 4. Results Thirty-seven nests were monitored over three nesting seasons in this study, including twentyfive in the coastal RP nesting area (n = 9 in 2019-20, n = 8 in 2021-22, and n = 8 in 2022-23) and twelve in the coral-islets of the GLS area (n = 2 in 2019-20, n = 8 in 2021-22, and n = 2 in 2022-23). Temperature surveys occurred simultaneously in the two nesting areas, over late November to March, representing a total of 2,029 days of survey (n = 1,289 days and 740 days over the RP and the GLS nesting areas, respectively). Overall, incubation periods were shorter in the RP (51.3 ± 2.2 days) than in the GLS (61.3 ± 5.4 days) (Kruskal-Wallis test, chi-squared = 16863.0, df = 1, p-value < 0.001***). Mean temperature over the full incubation-to-emergence period, duration of incubation and estimated sex ratios were assessed for each monitored nest (Table 11 SI Appendix). A GAM model was fitted to test the respective influence of the nesting season and the nesting area on the nest temperature over the full incubation period. No significant seasonal
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