Nest-site selection in individual loggerhead turtles and consequences for doomed-egg relocation

Area of Science:

• Marine Biology
• Conservation Genetics
• Reptile Ecology

Background:

• Egg relocation is a common conservation tactic for endangered reptiles.
• Concerns exist that relocating eggs might artificially select against traits for successful nest-site selection, especially if such traits are heritable.
• Loggerhead turtles (Caretta caretta) are a vulnerable marine species requiring conservation efforts.

Purpose of the Study:

• To assess whether relocating loggerhead turtle eggs imposes artificial selection on nest-site selection traits.
• To evaluate the impact of egg relocation on the genetic diversity of loggerhead turtle populations.
• To determine the efficacy of egg relocation as a conservation strategy for loggerhead turtles.

Main Methods:

• Monitored loggerhead turtle nesting at Mon Repos beach, Queensland, Australia, during the 2005 season.
• Measured distances of in situ (unrelocated) and relocated egg clutches from a stationary dune baseline.
• Assessed nest fate by mapping tidal inundation and storm erosion lines to predict outcomes for relocated clutches.

Main Results:

• Loggerhead turtles did not consistently select nest sites at specific distances from the dune baseline.
• Unsuccessful nest-site selection was widespread across the nesting population; 80.3% of turtles chose at least one unsuccessful site.
• Experienced females selected more successful nest sites than inexperienced ones, indicating a learning component in nest-site selection.

Conclusions:

• Doomed-egg relocation saves a significant proportion of loggerhead turtle progeny from natural threats.
• Artificial selection concerns are minimal because unsuccessful nest-site selection is not concentrated in a few individuals.
• Egg relocation is a justifiable and effective conservation strategy for loggerhead turtles, preserving genetic diversity.