Nest-Site Selection in Individual Loggerhead Turtles and Consequences for Doomed-Egg Relocation

Abstract:  Relocation of eggs is a common strategy for conservation of declining reptilian populations around the world. If individuals exhibit consistency in their nest-site selection and if nest-site selection is a heritable trait, relocating eggs deposited in vulnerable locations may impose artificial selection that would maintain traits favoring unsuccessful nest-site selection. Conversely, if most individuals scatter their nesting effort and individuals that consistently select unsuccessful nest sites are uncommon, then artificial selection would be less of a concern. During the 2005 nesting season of loggerhead turtles ( Caretta caretta ) at Mon Repos beach, Queensland, Australia, we measured the perpendicular distance from the original nest site to a stationary dune baseline for in situ (unrelocated) and relocated clutches of eggs. We observed the fate of in situ clutches and predicted what would have been the fate of relocated clutches if they had not been moved by mapping tidal inundation and storm erosion lines. In 2005 turtles deposited an average of 3.84 nests and did not consistently select nest sites at particular distances from the stationary dune baseline. Selection of unsuccessful nest sites was distributed across the nesting population; 80.3% of the turtles selected at least one unsuccessful nest site and when previous breeding seasons were included, 97% selected at least one unsuccessful nest site. Females with nesting experience selected more successful nest sites than females with little or no experience. Relocating eggs vulnerable to tidal inundation and erosion saves the progeny from a large percentage of the population and the progeny from individuals who may in subsequent years nest successfully. Our results suggest that doomed-egg relocation does not substantially distort the gene pool in the eastern Australian loggerhead stock and should not be abandoned as a strategy for the conservation of marine turtle populations.