Sentinel Species Research

Changing Ratios in Hawksbill and Green Sea-Turtle Hatchlings

As our world becomes increasingly warm, the effects of these rising temperatures affect species worldwide.

This phenomenon can have a drastic impact on sea turtles especially, as the sex of hatchlings in the nest is determined by temperature (hotter incubation resulting in more females while cooler incubation gives more males).

This climatic disturbance has led sea turtles sex ratio in rookeries around the world to be skewed more towards females, meaning that there are now more females than male hatchlings. Should this trend continue, and coupled with other man-made pressure on the species, it could lead to female only populations and the extinction of turtle species.

A study, conducted by Dr. Nicole Esteban and  the turtle team, investigated sand temperatures and their implications for hatchling sex ratios in the British Indian Ocean Territory (BIOT). The results from this study are promising. After collecting data for 2 years they found that sand temperatures were relatively cool during the nesting season of both species especially on sand shaded by vegetation. This predicts a hatchling sex ratio with slightly more males than females. This result is promising as it means that shaded nesting beaches will continue to provide a substantial number of males hatchlings into a female dominated regional population and warming world.