Local educator studies terrapin population in Northwest Florida
As the sun rises on a gulf coast salt marsh there is barely a breeze. The placid water is slick as glass and resembles a sheet of gray ice. The only movement is the occasional swirls of mullet and redfish that are awaken as our canoe slides over their evening resting spots. Osprey whistle and dive searching for a morning breakfast to take back to their nest of chicks that sits on top of an old tree. As we paddle along the bank the water is clear enough to see blue crabs, who were feeding on organisms at the base of the marsh grass, scurry into the depths. Clumps of ribbed mussels can be seen in the wet, glistening mud and marsh periwinkle snails move up the stalks of needlerush. This is the haunt of the elusive diamondback terrapin, and the reason we are here.
My wife Molly, sister-in-law Betsy and I have been searching the marshes of the Florida panhandle for the emydid turtle since 2006. It is the only turtle species in the United States that resides in brackish salt marshes and mangrove swamps. It was once quite common along the east and gulf coast of the country but has been slowly declining in population since the 1950s.
In 2001 a group of terrapin researchers formed a working group with regional chapters. The purpose of the group was to compare field notes and work together to develop conservation practices to help this animal. A few members of the Florida Working Group are currently searching the Gulf coast to see if the animals are still in our area; Molly, Betsy and I are searching the Florida Panhandle.
We continue to paddle through “Osprey Cove” in Santa Rosa County, searching for the white heads just above the water, curiously staring at us, wondering what we are up to. We also check the needlerush along the shoreline where they may be basking in the morning sun.
Not finding anything we move on to the sandy nesting beach near the mouth of the bay to search for the tracks of nesting females, the remnants of eggs from a previous nest that have been raided by raccoons, or maybe a nesting female slumbering up out of the marsh to lay the next generation of terrapins. The sun is rising now and a mild morning breeze begins to beat down the oppressive summer heat. We carefully check near the bushes among the blackberry vines along the high side of the beach. Tracks of the gulf salt marsh snake can be seen along with those of the great blue heron, raccoon, and even an occasional marsh rabbit. All are excited when we find the tracks of a terrapin and hope to be lucky enough to identify where she laid her nest. They are notorious for concealing their nest from predators, and from people, showing that they are excellent mothers. Notes are kept on environmental conditions and the number of tracks and nest found. This gives us some idea of how many nesting females are in the population.
Terrapins spend the winter buried in the mud of the marsh. In spring they begin to congregate in the small ponds and lagoons where breeding takes place. Gravid females generally visit their nesting beaches near the high tide in the middle of a sunny day, the peak months are May and June. She will excavate a five to seven inch hole where six to eight oval eggs are buried (sometimes as many as 20!).
As with other species of turtles, the temperature of the nest determines the sex of the offspring. Also as with other species of turtles, terrapins may lay more than one clutch in a season. After 70 or so days, the young terrapins begin to hatch from their eggs. They may break the surface of the nest and scrabble for the nearest vegetation, or they may remain in the nest for the entire winter feeding off of their yolk reserves waiting for next spring before they go. Like many other turtles this is the most dangerous time in a terrapin’s life, most do not survive the first year.
Not finding any nesting females, but lucky enough to discover the tracks of a few, we paddle towards “Turtle Cove” where we frequently encounter the heads of adult terrapins checking us out from the middle of the pond.
There are few local fishermen throwing cast nets on the numerous schools of mullet, and a few having luck catching flounder with hook and line. Most have not heard of terrapins but agree to let us know if they see any heads. We paddle to the east side of the pond where the sun is behind us. This cuts down on the glare and the sunlight reflects a brilliant white off of the heads of the turtles. We drift quietly for about 30 minutes counting the number of heads we see in that time. The osprey and blue herons are still fishing and the pelicans are now joining the hunt. The silence is broken only by the occasional loud quacking of the clapper rail, who feeds on invertebrates in the grass just beyond our view. Now is a good time for us to have our morning snack and some cold water.
Terrapins do not seem to migrate as sea turtles do but rather spend their entire lives in the same marsh. Within these marshes their favorite haunts are sometimes very hard to find, particularly when the populations are as low as they seem to be. They spend their time feeding on shellfish and basking in the sun to warm them selves. They have a bad habit of swimming into crab traps to feed on the bait and become trapped themselves. Being air breathing reptiles many drown this way and it is particularly a problem with the number of derelict traps (abandon / un-fished traps). It is hard to say how many terrapins drown this way each year along the gulf coast but along with habitat loss and heavy predation by raccoons, it is one of the major problems these animals now face.
We have been paddling for about four hours now. The wind is beginning to pick up as is the human traffic. After checking a few of the creeks that feed these ponds it will be time to head for lunch before we do the search all over again in the afternoon.
Next week we will move onto another location somewhere along the panhandle trying to find where these guys live and how many are still there. At the time of this writing we have found at least one record of a terrapin in every panhandle county except Okaloosa. The only nesting beach we have found so far is in Santa Rosa County. The trapping studies we have done in Santa Rosa suggest there are between 30 and 60 animals in that population. It appears that the terrapins are still in this area but their numbers are quite low. It is hard to control development and raccoons, but we hope folks who use crab traps will check them frequently and consider using an “excluder” designed to keep terrapins out of these traps. Studies have been conducted in New Jersey and Florida that show these “excluders” do not lower the crab catch but do lower the number of terrapins. If more local crab fishermen would use these maybe we could save a few terrapins.
About Terrapin Turtles
There are seven subspecies of the diamondback terrapin (Malaclemys terrapin). Terrapins in general can be distinguished from other turtles by their choice of habitat (salt marshes with salinities generally higher than 5 ppt) and their unique skin markings (most have light blue to khaki skin with dark spots or bars). The Northern Diamondback Terrapin (M.t. terrapin) exist from the Massachusetts area to about the Carolina’s. From the Carolina’s to about Daytona Beach, the Carolina Diamondback Terrapin (M.t. centrata) is found. From Daytona Beach to Miami is the range of the Florida East Coast Terrapin (M.t. tequesta). The Florida Keys is the haunt of the Mangrove Terrapin (M.t. rhizophorarum). From the Everglades all the way around the Gulf Coast of Florida to about the Walton/Okaloosa County line is the home of the Ornate Terrapin (M.t. macrospilota). From Walton County FL to the Louisiana/Texas border was the range of the Mississippi Terrapin (M.t. pileata). And the final terrapin is the Texas Terrapin (M.t. littoralis).
Five of the seven subspecies of terrapins live in Florida, and two subspecies live in the Pahandle region.
Diamondback terrapins are the only true brackish water turtles in the United States. They live in extensive salt marshes where creeks and small ponds can be found.
They hatch from oblong eggs that are about 1.5” long in late summer and early fall where they immediately move to the closest vegetation. The tendency is for them to spend their entire life in this marsh.
Rick O’Connor is a Marine Science Educator at Washington High School in Pensacola. He has been researching and teaching about terrapin turtles since 2006. He can be reached via email at ROconnor@escambia.k12.fl.us.