92 environmental temperature during the middle third of the embryogenesis (Standora and Spotila 1985; Hawkes et al. 2009; Fuller et al. 2013). Values above the pivotal temperature, where a 1:1 primary sex ratio is produced, will generate mainly female hatchlings, while values below produce mainly male hatchlings (Mrosovsky and Yntema 1980; Fuentes et al. 2024). However, this special case of phenotypic plasticity may not be advantageous in the current context and could potentially increase the risk of extinction under the effects of anthropogenically induced climate change (Hulin et al. 2009; Santidrián Tomillo and Spotila 2020). Temperature rises are predicted to increase the frequency of female-biased hatchling cohorts (Laloë et al. 2014; Patrício et al. 2017, 2021; Monsinjon et al. 2019b), a phenomenon referred to as ‘population feminization’, but also to impact incubation duration (Booth and Astill 2001), hatching success (Sim et al. 2015), hatchlings survival, morphology, fitness or locomotion capacities (Laloë et al. 2014, 2016; Sim et al. 2015; Booth 2017; Hays et al. 2017; Kobayashi et al. 2018). In extreme cases, it may compromise the long-term viability of populations (Fuentes et al. 2011; Santidrián Tomillo et al. 2015; Laloë et al. 2016; Jensen et al. 2018; Maurer et al. 2021). Globally, female biased hatchling sex ratios dominate sea turtle populations (Hays et al. 2014; Fuentes et al. 2024), with more female bias occurring at rookeries located closer to the equator (Witt et al. 2010; Katselidis et al. 2012). However, sea turtles are polyandrous with males able to breed with many females, and they also breed more frequently than females (Lee and Hays 2004; Hays et al. 2014, 2023). Therefore, moderate female skewed hatchling sex ratios will translate into more balanced operational sex ratios (Hays et al. 2014). A growing number of studies suggest that sea turtles may adapt to the projected temperature increase by displaying both phenological (Weishampel et al. 2004; Pike et al. 2006; Dalleau et al. 2012; Almpanidou et al. 2018; Fuentes et al. 2024) and spatial distribution shifts (Morjan 2003; Kamel and Mrosovsky 2006). Nevertheless, it is still unclear whether this behavioral adaptation can occur fast enough to counteract the deleterious and rapid effects of global warming (Almpanidou et al. 2018; Monsinjon et al. 2019b; Laloë and Hays 2023; Fuentes et al. 2024). Alternatively, nesting habitat diversity within a population’s nesting area may provide a gradient of thermal conditions favorable to a balanced and effective reproductive output. Indeed, several environmental factors influence nest temperatures, such as substrate type (Laloë et al. 2014; Mitchell and Janzen 2019), substrate moisture (Ackerman 1997; Gatto et al. 2021), vegetation cover (Kamel 2013) and weather conditions (Fuentes and Abbs 2010; Lolavar and Wyneken 2015; Laloë et al. 2020; Hays et al. 2021; Patrício et al. 2021; Porter et al. 2021). A significant part of the critically endangered loggerhead turtle (Caretta caretta) South Pacific subpopulation breeds and nests in the New Caledonian archipelago (Limpus and Casale 2015). Two areas in particular aggregate 10-25% of all reproductive females of the
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