Loggerhead hatchlings leaving a nest in a rare daytime emergence (Credit: Barbara Bergwerf)
It’s hatching time for the loggerhead nests on our two islands as summer begins to wind down. Tiny hatchlings know it really “takes a village” when it’s time to emerge from their nest, buried two feet down in the beach sand. With more than 100 eggs in each nest, they incubate for around 55 days. Then, they cut themselves out of their soft, leathery shells and begin the hard work of climbing to the surface, leaving their empty shells behind.
Their sex is determined by the amount of heat from the sun during the middle weeks of incubation—temperatures above 85 degrees can produce females, and below that, males. There can be a mixture in the nest depending on an egg’s position in the clutch. As their small, hard shells straighten after weeks of being curled inside the egg, they dig upward. This journey can take several days. Once near the surface, they wait under the sand until they sense a cooldown, indicating the sun has set and night has come.
Under the cover of darkness, they begin their dangerous journey across the sand, where predators such as ghost crabs, coyotes and ants may catch them. They “boil” out of the nest quickly—like popcorn popping—and spread across the beach, finding safety in numbers. Their cues to reach the ocean are to move downhill and crawl toward the brightest area they see. This might be the moon and stars if they’re lucky—or streetlights, house lights or even the skyglow from Mount Pleasant or Charleston if they’re not.
If they make it to the water, they instinctively swim against the waves. Once beyond the breakers, they’re believed to use magnetic crystals in their brains to navigate latitudes during their migration. Within days, they reach the Gulf Stream and find shelter and tiny meals in rafts of Sargassum weed. Microplastics pose a danger at this stage, as many hatchlings ingest them.
They follow the circular current of the Atlantic Ocean, and if they survive, return to South Carolina in about 15 years to forage—not only in the ocean but also in waterways, marinas and creeks—as subadults until they reach breeding age around 25 years. Unfortunately, only a very small number will survive the hazards ahead, including predators, boat strikes and other threats.
As of July 30, 11 of the 39 total nests on our two islands had hatched and produced turtles. Three days after a hatch, the Turtle Team excavates the nest to collect data for the South Carolina Department of Natural Resources, including how many eggs were laid, how many empty shells were found, how many eggs failed to develop, and how many hatchlings, dead or alive, were found at the time of the inventory.
So far, the season is going very well, with the hatch success average at 81.6% for the Isle of Palms and 92.7% for Sullivan’s Island.