2018 Diamondback Terrapin Panhandle Survey Report

Objective:

 

Diamondback terrapins (Malaclemys terrapin) are the only resident brackish water turtle in the United States.  Found from Massachusetts to Texas, the terrapin frequents salt marsh creeks where the bottom is muddy, and a high-dry beach is nearby for nesting.  In some locations within its range, terrapins have chosen to nest along side roads or nearby airports.  This has unfortunately led to road kill issues.

The diamondback terrapin is the only resident turtle of coastal marshes and mangroves in the United States.
Photo: Molly O’Connor

Fans of shellfish, terrapins eat a variety of mollusk and crustaceans – having favorites in different parts of their range.  They nest nearby their resident marsh and usually do so on sunny days.  A major predator of these nests are raccoons, who – on some beaches – have raided as many as 90% of the known nests.

 

There is very little known about terrapins in Florida and even less in the Florida panhandle.  In 2005, the Institute of Coastal and Marine Studies (ICAMS) – a high school marine science program based at Washington High School in Pensacola, began to survey local marsh beaches in the Pensacola area searching for terrapins, or sign of terrapins.  This was to address the following questions:

1)      Do terrapins still exist in the Florida panhandle?

2)      If so, how many are there and what is the status of their population?

Today, citizen science volunteers working with Florida Sea Grant are continuing this work.

 

Method:

 

Trained citizen science volunteers select marsh beaches near their homes that have a high probability of terrapin nesting.  These volunteers visit and survey the beaches at least once a week during the months of May and June (peak nesting season).  The number of heads seen in the water, tracks on the beach, depredated nests by raccoons, and females on the beach are recorded.

 

This data is also used to determine the relative abundance of terrapins using a 16-day nesting cycle.  It is assumed that:

  • All mature females will nest each year
  • We know where all nesting beaches for this population are located and those are being surveyed
  • All nesting females will lay more than one clutch/season but only one clutch/ 16 days

Another assumption is that the sex ratio is 1:1. Sex ratio data varies from location to location.  Another ratio in the panhandle was listed as 3.3:1.

 

2018 Results

 

County # of volunteers # of surveys # of terrapin records Frequency of Occurrence
Escambia 5 34 10 .11
Santa Rosa 9 84 25 .30
Okaloosa 3 1 0 .00
Gulf 3 20 0 .00
TOTAL 20 139 35 .25

 

Escambia County

Seven of the 10 records reported were not confirmed as terrapins.  This location, Old River, should be surveyed again to do so.

Surveys included the Perdido Key area, and Pensacola Beach – at least one record was found from each.

 

Santa Rosa County

The majority of the surveys and records came from this county.  Records were reported from Navarre Beach and the Garcon Peninsula area.  The only 16-day surveys conducted in 2018 were at Navarre Beach.

16-day Surveys

4 Surveys – Navarre Beach

Number of females recorded for each – 0,0,1,8

This suggests there are 8 nesting females in this population

Total population estimated to between 16-26 individuals

 

Okaloosa County

Only one survey was conducted here.  This was to a group of islands near Mary Esther in an area called “Pirates Cove”.  This is on USAF property.  This area needs more surveying.

 

Gulf County

Twelve surveys were conducted at an area known as Money Bayou, the others near Tyndall AFB.  Though no records were found in 2018, both locations have promise and more surveys are needed.

 

Summary of all Surveys 2005-2018

 

County # of surveys # of records of terrapins Frequency of Occurrence
Escambia 170 19 .11
Santa Rosa 255 107 .42
Okaloosa 9 0 .00
Walton 4 1 .25
Gulf 21 1 .05
TOTAL 459 128 .28

 

Escambia County

All records have been reported from the Big Lagoon and Big Sabine area.  Though few surveys have been conducted in the bayous, no terrapins have been found there.  Based on these data, there is an 11% chance of encounter a terrapin, or terrapin sign, when visiting these beaches.

 

Santa Rosa County

This has been the hot spot for our surveys – with a 42% chance of finding at least sign of terrapins when visiting these beaches.  This is the only location where the 16-day surveys have been conducted.

Year Location # of females nesting during a 16-day period Estimated population
2008 Garcon Peninsula 7 14-23
2009 Garcon Peninsula 7 14-23
2010 Garcon Peninsula 16 32-53
2011 Garcon Peninsula 5 10-15
2015 Navarre Beach 6 12-20
2016 Garcon Peninsula 2 4-6
2018 Navarre Beach 8 16-26

 

Okaloosa County

Okaloosa has the lowest amount of salt marsh acreage in our survey area, thus the lowest probability of terrapin inhabitance.  We have one record of a hatchling crossing US Highway 98 near Mary Esther cut-off and believe more surveying effort here may yield records.

 

Walton County

We only have one record of a terrapin in this county.  That was of a basking individual in Hogtown Bayou.  The habitat looks promising and more surveying effort here may yield more records.

 

Bay County

We have not surveyed Bay County.

 

Gulf County

Though our records indicated few surveys, low frequency of occurrence, more survey effort by students at the University of Florida in this area have yielded significant records of terrapins in this county.  We will continue working with our volunteers there.

 

SUMMARY

 

Addressing objective questions:

1)      Yes, terrapins do still exist in the Florida panhandle

2)      Only two beaches have had 16-day surveys conducted.  Based on these:

–          Indian Bayou has had estimations anywhere from 6-53individuals

–          Navarre Beach has had estimations anywhere from 20-26 individuals

There have not been consistent 16-day surveys to determine population status