Stay in the know about wildlife, water quality, and ecosystems on Sanibel and Captiva Islands and in Southwest Florida

Diamondback Terrapin Monitoring Begins

May 13, 2024
diamondback terrapin sccf

SCCF recently began its seasonal efforts to monitor local diamondback terrapin (Malaclemys terrapin) populations, which will inform our conservation efforts for this unique turtle species. 

Named for the diamond pattern on their backs, diamondback terrapins are the only turtle in the western hemisphere to live exclusively in brackish water (a mix of fresh and sea water). Southwest Florida is home to two of seven subspecies — the mangrove diamondback terrapin (Malaclemys terrapin rhizophorarum) and ornate diamondback terrapin (Malaclemys terrapin macrospilota).

diamondback terrapins
Female (left) and male (right) diamondback terrapins. Females are larger than males and are typically 5-9 inches in length. Recent genetic data suggests the terrapins in SCCF’s research are most closely related to the mangrove subspecies.

Because terrapins often share the same estuarine habitat as crabs, accidental capture in crab traps is a huge threat to this species, which is why all recreational crab traps in Florida are required to have terrapin bycatch reduction devices

terrapin bycatch reduction device
The 2-by-6-inch terrapin exclusion devices can be seen in orange.

SCCF is offering free terrapin bycatch reduction devices for crab traps — please email to pick them up.

Each May through August, SCCF biologists monitor several diamondback terrapin sites around Lee County to find terrapins and tag them with notches and microchips.

“This way, when we catch them again, we can identify if it’s the same turtle,” said SCCF Wildlife Biologist Mike Mills. “This helps us estimate the population health, sex ratios, age ratios, growth, and other factors.” 

SCCF began research on diamondback terrapins in 2012, becoming the first team in the area to deploy satellite transmitters on gravid females to identify important nesting areas. Having this information allows us to prioritize these areas for conservation.  

Additional threats to diamondback terrapins include illegal poaching, loss of nesting and foraging habitat, boat/vehicle strikes, and poor water quality. 


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