Bonaire provides nesting habitat for three species of marine turtles: hawksbill, green, and loggerhead turtles. Hawksbills are responsible for the most activity and probably deposit more than 50 nests island-wide. Green turtles and loggerheads lay fewer nests, perhaps less than 20 for each species.
(source: Sea Turtle Conservation Bonaire): Bonaire’s beaches receive an annual average of 75 nests. How do we know that it’s important to protect these nests in the interests of sea turtle survival? We know because detailed counts reveal that large nesting colonies are rare. For example, only 0.4% of all known species-specific nesting sites in the Wider Caribbean Region receive more than 1000 hawksbill crawls per year.
On the 1,311 known nesting beaches in the region, roughly half support fewer than 25 nest crawls per year. These counts provide an important perspective. It turns out that protection of the many small nesting colonies is critical if we are to maintain hatchling production and genetic diversity.
The research yields important information over time about population status. By comparing nesting data from year to year, we gradually see trends emerge. Because annual variation in nesting activity is normal in marine turtles, only data collected long-term (more than 10 years) will be truly indicative of how healthy these nesting turtle populations are.
In an effort to understand how nest temperature is affecting the ratio of male to female hatchlings on Klein Bonaire, STCB, in collaboration with University researchers, is using temperature dataloggers deployed at nest depth to monitor sand temperature during the year.
This interesting study is based on our knowledge that for sea turtles, sex is not determined at fertilization. Instead, temperature plays an important role: eggs in warmer nests tend to develop into females, and cooler nests produce more males.
This study may give us insights not only into the relative numbers of males and females produced on Bonaire but also into the long-term effects of climate change.
For more information on turtles click on the other turtles in the ocean!