Diamondback terrapins are found along the Atlantic Coast from Massachusetts southward to the Florida Keys. They are also found along the Gulf Coast extending westward to Texas. They feed primarily on snails, worms, fish, and crabs. In the marshes of Kiawah, terrapins eat mostly periwinkle snails and fiddler crabs. Female terrapins reach maturity at 6 years of age (compared to 3 years for males). Terrapins breed in early spring and females will leave the water in late spring or summer to lay their eggs, often on the sandy banks of hammock islands. Females typically lay 4-18 eggs and the hatchlings emerge after about 3 months.
Population status and how you can help
In the late 1800’s and early 1900’s, terrapins were considered a culinary delicacy and terrapin soup was a common menu item in most fine restaurants along the Atlantic coast. For this reason, terrapin populations suffered a significant decline due to overharvesting. As the taste for terrapin soup diminished, terrapin populations were able to rebound but they continue to face significant threats at the present time. One of the biggest threats to our local terrapin population is the accidental death of terrapins in commercial and recreational crab traps.
Because of this threat, The Town of Kiawah Environmental Committee is sponsoring a community effort to help the rare diamondback terrapin. A device, known as a Bycatch Reduction Device (BRD), can be installed into the openings of crab traps to dramatically decrease the likelihood of terrapins being accidentally captured and drowned. Research has also shown that crab traps outfitted with BRDs actually catch more crabs. BRDs are currently being used in a number of coastal states, including Maryland, Florida, Louisiana and Alabama. During the spring breeding season, terrapins are more susceptible to drowning in crab traps. Male terrapins are actively searching for females and it is possible for a large number of males to follow a single female into a crab trap.
The Town of Kiawah encourages property owners and visitors to utilize BRDs, and now is the time to have them installed. If you already own a crab trap, you can bring your crab trap to the Nature Center at Night Heron Park to be outfitted free of charge with BRDs. Traps should be clearly labeled with your name & phone number and can be dropped anytime. Please call the Nature Center at 768-6001 and a mutually convenient time will be arranged. If you are planning to purchase a crab trap, ask your vendor if they have traps already fitted with BRDs.
Kiawah Island has been a focal point for terrapin research over the last 20 years. Researchers, including Dr. Whitfield Gibbons (Savannah River Ecology Laboratory) and Dr. Michael Dorcas (Davidson College), have been capturing and marking terrapins in Kiawah creeks since 1984. Their research has shown a marked decrease in terrapin numbers and a shift toward an older age structure with more females than males. These data suggest that young turtles and males are suffering high mortality. This is consistent with the type of mortality one would expect to see from drowning in crab traps. Adult Males and young turtles are much smaller than adult females and are able to enter crab traps easily, while adult females cannot.
The diamondback terrapin is Kiawah’s only brackish water turtle. Terrapins are 5-8 inches long (females are twice as big as males) and weigh between 0.5 lbs and 1.5 lbs. These turtles get their name from the striking diamond-shaped pattern on their top shell. They are typically light brown or gray on top and yellow to olive on the bottom. Their whitish-gray skin is covered with unique black spots and wavy markings. Terrapins can live more than 20 years.