Environmental Factors Affecting Hatch Success in the Loggerhead Sea Turtle (Caretta caretta)

The loggerhead turtle (Caretta caretta) is a species federally listed as “threatened” whose global populations are declining. Georgia Department of Natural Resources conservation protocols for this species require the daily monitoring of nesting activity and permit physical relocation of nests which are at risk of being eroded or flooded by storms and high tides in order to increase hatch success--the proportion of hatched to unhatched eggs. Relocated nests are moved to an area with higher elevation in order to avoid flooding, but other variables such as increased temperature and decreased moisture are introduced when relocating. For years temperature and moisture have been regarded as the most important factors that contribute to hatch success but these variables are not always directly considered when relocating nests. It is likely that other environmental variables have an effect on hatch success and influence temperature and moisture. The hypothesis that a combination of geological and biological factors better predicts hatch success compared to temperature and/or moisture alone was tested. Secondly the environmental variables which influence temperature, moisture, and likelihood of tidal washover were also examined to evaluate their impact on hatch success. Loggerhead nests on Ossabaw Island, Georgia were monitored throughout incubation; upon incubation completion, hatch success was calculated. For all nests, temperature, moisture, vegetation cover and composition, elevation, dune morphology, and tidal washovers were recorded. These variables were analyzed to assess their individual and combined influences on nest conditions and ultimately on hatch success. In addition to number of washover events, temperature, and moisture, nest vegetation and elevation were important predictors of hatch success in loggerhead sea turtle nests and should be considered when nest relocation is required