By Mary Pringle for The Island Eye News
When a sea turtle crawls ashore and does not lay eggs, scientists call this a non-nesting or “false crawl.” This happens on every nesting beach, not just ones like the Isle of Palms and Sullivan’s where there are people, lights and dogs. And for some reason it is happening many more times this season than in recent ones. What can cause a false crawl?
Here are some of the causes that we have seen on our islands:
- Lights that can be seen from the beach. That is why our islands and most in the state have ordinances that prohibit any lights visible on the beach after dark. This is especially important when hatchings are coming out of the sand. But it can also discourage a nesting female who is searching for a safe dark place to lay eggs.
- Encounters with people and dogs. Recent incidents at Folly Beach and Garden City when people harassed nesting turtles or tried to photograph them have been in the news. Everyone should remain at least 40 feet away and not make noise or shine flashlights if they see a turtle coming ashore.
Flash photography is strictly forbidden when adult or hatchling turtles are present.
- Debris such as tents, umbrellas or chairs on the beach. This is one reason why the rental companies are required to remove them and tents must be brought in every night. If they are left out on the IOP, the police will tag them and have Public Works remove and discard these items the next day. Sometimes there are natural objects like dead trees or driftwood that turtles run into and turn around.
- Eroded or steep dunes from escarpment. At Breach Inlet a turtle false crawled on June 10. We could see that she kept trying to find her way up onto the sheer wall of a dune that had been chopped off into a vertical wall by high tide erosion recently. Finally after many tries, her tracks led back into the water.
- Flat beaches or lack of dunes. Sometimes on Sullivan’s Island we have seen tracks that go on and on before finally leading back to the ocean. Nesting turtles prefer to come out of the ocean and climb right up onto a dune to lay eggs. This is a problem in Wild Dunes since the latest renourishment project and has created a very wide flat beach which can flood. Multiple tidal pools, sandbars or gullies
at low tide may also discourage a nesting female.
- Sand compaction and moisture content. Sometimes the sand can get very hard making digging difficult especially after a renourishment project. For this reason it is required under the project permit that it be tested and even tilled to loosen it if necessary. During times of drought the sand can become so dry that dry sand keeps falling into the egg chamber. Most loggerheads will not lay in wet sand either.
- Deep holes dug by people. These are dangerous for nesting loggerheads as well as for people on the beach. It is a mystery why people take large shovels to the beach to do this. Few of them fill them in. Sand castles do not harm turtles, but holes are a deterrent to nesting and a danger. It has been documented that an adult loggerhead died in Florida from falling into one and many hatchlings have died after being trapped by these. If you see people doing this, a friendly reminder to please fill it in when they finish is a good idea. If you find one left behind on IOP, you can report it to the police at 843.886.6522 for Beach Services to fill in.
- Unknown reasons. We suspect that one turtle has been doing a lot of false crawling at the south end of the Isle of Palms. The tracks usually measure 23” between rear flipper claw marks. She usually goes up the artificial berm created after the hurricanes, then crawls down the steep slope behind it toward swimming pools before finally giving up and climbing back over and out to the ocean. Or as at Cape Island, the reason remains unknown.
On Cape Island in the Cape Romain National Wildlife Refuge near McClellanville there have been 793 nests and 2,166 false crawls reported as of June 12. I was told by one of the US Fish & Wildlife staff there that on only one day they had 24 nests and well over 100 false crawls. As of the same date there have been 3 nests and 11 false crawls on Sullivan’s and 27 nests and 21 false crawls on the Isle of Palms.
We have never seen any scientific explanation for false crawls. Sometimes people joke that perhaps it was false labor and the contractions stopped. Another explanation could be that just like all of us, loggerheads like to take a nice walk on the beach. Perhaps it will remain a mystery.
Mary Pringle has been the Project Leader for the Isle of Palms/ Sullivan’s Island Turtle Team since 2000. It is one of about thirty nest protection projects under the South Carolina Department of Natural Resources. She is also on the Sea Turtle Stranding and Salvage Network.