August 2008

Amazing Species: Loggerhead sea turtles return to local beaches

Author: Carlos Chacon | Photographer: Carlos Chacon

The loggerhead sea turtle has been in existence for millions of years. These gentle giants thrived until the last century, when interactions with humans began taking a toll. Now, habitat destruction, poaching and the unintentional but widespread drowning of turtles by commercial fishing fleets of other countries threaten to wipe them out.

The loggerhead is considered an endangered species by the International Union for the Conservation of Nature, and has been considered a threatened species by the U.S. government since 1978. According to the South Carolina Department of Natural Resources, the nesting population of loggerhead sea turtles has shown a 60 percent decline since the 1980s.

Loggerhead sea turtles can grow to be more than three feet long, and they can weight over 300 pounds.

Hilton Head Island is the fourth most important nesting beach for loggerhead sea turtles in South Carolina. Hilton Head averages 120 nests a year, although the numbers of nests in a given year could be as high as 218 (as happened in 1999) or as low as 49, as was the case in 1993. They begin nesting on Hilton Head Island by the second week of May. Our first nest for the 2008 nesting season was laid on May 11.

The female turtle will lay four to six nests in a season, and each nest contains an average of 120 eggs. Some nests may have only 60 eggs and others can have close to 200. The eggs will be incubated by the sand, and the mother turtle will never know her hatchlings.

After approximately 60 days of incubation, the baby turtles will hatch out of the eggs. The hatchlings break the eggshell with a special point on their beak called the egg tooth. Once out of the egg, the hatchling will stay in the nest for up to three days before it emerges on to the beach. The hatchlings can’t really dig their way out of the nest; instead they make their way by a process know as proto-cooperation. After a couple of days in the nest, one hatchling will start moving its shoulders, and this will trigger a chain reaction which will result in all the surrounding hatchlings moving their shoulders. This movement will cause the sand from the top of the nest to trickle down in between the hatchlings’ shoulders. In this manner, sand from the top of the nest will shift to the bottom of the nest, and the group of baby turtles will rise like an elevator.

Once the hatchlings are one or two inches below the surface of the nest, they will stop moving and will wait until nighttime to crawl out of the nest. Hatchlings will know that is nighttime by the change in temperature between day and night.

Once out of the nest, the hatchlings’ instinct will tell them to dash as fast as they can toward the brightest point on the horizon. In a pristine beach where there is no artificial light, the brightest point on the horizon is always the ocean, since water reflects light better than land. The baby turtles will see the ocean reflecting light from the moon, stars, or the clouds. Today, it is almost impossible to find a beach in the world without an artificial light.

On developed beaches like Hilton Head Island, lights can pose a significant risk to sea turtle hatchlings. The Town of Hilton Head has a light ordinance that requires all lights that are shining on the beach to be turned off from dusk to dawn from May 1 until October 31. Additionally, any windows facing the beach must be covered. Artificial lights can discourage the loggerhead sea turtles from leaving the ocean to lay eggs or disorient adults after they have laid the eggs, or hatchlings leaving the nests, making them unable to find their way to sea. Violating the law can result in severe fines. Officials from The Town of Hilton Head Island patrol the beaches to make sure all beachfront lights are out.

Once the turtles have reached the ocean, turtles born on the East Coast of the U.S. will embark on an incredible journey around the world. Hatchlings from Hilton Head Island will swim 60 miles off shore until they reach the Gulf Stream, then they will travel north with the Golf Stream and later east, across the north Atlantic Ocean into the waters of Europe. They will swim around the Canary Islands, and then south to the waters of Africa along the west coast of Morocco, and the Sahara. They will swim in the waters around the Azores Islands, and will cross the Atlantic Ocean one more time, crossing the equator, into the waters of the northern coast of South America, and then north through the Caribbean. Once they are back to the East Coast of the U.S. they will hang out as juveniles until they became sexually mature. Once adults, females will return to the same region where they were born to lay their eggs. Males will never touch dry land again.

Carlos Chacon serves as the Coastal Discovery Museum’s manager of natural history and sea turtle protection project manager.

Protecting the Sea Turtle
The Hilton Head Island Sea Turtle Protection Project has been in operation since 1985. The project is fully funded by the Town of Hilton Head Island and is managed by the Coastal Discovery Museum.

Near dawn, you can see staff from the Sea Turtle Protection program riding their ATVs on the beach, checking for new nests. Nests laid below the high tide line are relocated closer to the dunes, so they won’t be flooded by a very high tide. After 60 days, hatchlings emerge when the temperature drops at night. After the hatchlings leave the nests, the staff inventories each nest to determine how many eggs successfully hatched.

Daytime Turtle Talks and Walks are offered on Wednesdays during the summer. Evening Turtle Talks and Walks are offered on Tuesdays and Thursdays during the summer. Throughout the year, members of the Sea Turtle Protection Project are available to present educational programs to groups of any age. Please contact the Museum for additional information, (843) 689-6767.

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