Repeatability of nesting preferences in the hawksbill sea turtle, Eretmochelys imbricata, and their fitness consequences

We investigated individual nest site choice behaviour and its fitness consequences in female hawksbills nesting at Trois Ilets, Guadeloupe. We found a significant repeatability of nest site choice, suggesting that this behaviour is heritable and may show the potential for further evolution. By looking at possible consequences of nest site choice, we found that hatching success was similar among different beach zones, but the ability of hatchlings to emerge from the nest was impaired in areas subject to tidal inundation. Sea-finding tests showed that hatchlings were more susceptible to disorientation in areas deeper in the forest. Maintaining phenotypic diversity in nest site choice could derive from variation in the environment, where a constantly shifting balance between phenotypes would be promoted by environmental change over time. Alternatively, the different nesting behaviours could be maintained though frequency-dependent selection. Phenotypic sex of sea turtle embryos is determined by the incubation temperature of the nests, and different beach zones have different thermal properties. Females that nest in areas that produce the rarer sex may therefore gain a fitness advantage.