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

Peak Breeding Time for Diamondback Terrapins

April 12, 2021
Diamondback terrapin (Malaclemys terrapin) monitoring and research is in full swing in the SCCF Wildlife & Habitat Management Department. SCCF biologists are collecting data on their distribution and abundance on Sanibel and surrounding areas. 
Breeding activity is currently at its peak and female terrapins in mangrove waterways are frequently being trailed by one or more males.
“As the average air temperature increases throughout the spring, so does the breeding activity until females begin their nesting cycle in late April and beginning of May,” said SCCF Wildlife & Habitat Management Director Chris Lechowicz. They will lay up to four clutches of eggs through the spring and summer months.
Terrapins are a brackish water species of turtle that live along the coast of the eastern United States from Massachusetts to Texas. Their habitat throughout most of their range is tidal salt marsh, but on much of the west coast of Florida, as well as the Florida Keys, they primarily live in mangrove waterways. 
SCCF has found that terrapins in their study areas can tolerate and thrive in water with salinities (salt) double that of sea water, which is on average around 35 practical salinity units (psu). Some tidal creeks where terrapins occur on Sanibel have salinities around 70 psu, Lechowicz noted. 
They have been reported in waterbodies with salinities over 100 psu in the Florida Keys. However, typically they occur in estuaries with salinities less than 30 psu and drink rainwater or water containing less than 20 psu. Terrapins that live in hypersaline areas drink rainwater as it collects at the surface of the waterbody before it mixes with the salt water. 
This unique species of turtle has an interesting life history. We still do not know exactly where hatchlings spend their first one to two years after hatching.
“We have never captured or documented a terrapin with less than about a 3-inch in carapace length in a mangrove creek, lake, and other waterways,” Lechowicz said. “These areas are full of predators such as fiddler crabs and mangrove tree crabs, so hatchlings would have a hard time existing there.” 
Studies in northern states have shown hatchlings spend their first two years in terrestrial habitats with very little water. What we do know is that we document them in parking lots, hiking trails, and backyards at odd but consistent times of the year. 
If you see juvenile (less than 3 inches) terrapins on or around Sanibel, please take a picture and report them to


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