Houston ChandlerViews:
Few Spotted Turtle Records in the Southeast
Our recent publication titled “Ghosts of the swamp: Challenges associated with surveying for Spotted Turtles (Clemmys guttata) in the southeastern United States” seemed like an appropriate topic to discuss as the calendar moves into October (Chandler et al. 2024). This work examines the results of multiple years of Spotted Turtle surveys across several southeastern states. Throughout most of this survey effort, it felt like we were searching for ghosts within large wetlands that seemed devoid of Spotted Turtles.
To give a bit more context for this project, one of the main challenges for implementing Spotted Turtle conservation measures in the southeast is a lack of knowledge about the distribution of turtle populations. How can you protect and manage (or even study) populations without knowing where they are? For example, when we began working with Spotted Turtles in Georgia in 2014, there were just 129 records from the entire state. Only 87 of those records were reported from 1990 to 2013, and a majority of records represented observations of individual turtles crossing roads with no associated data about the habitat or population (Stevenson et al. 2015). The situation in Florida (Berry and Gidden 1973, Meylan 2006) and South Carolina (no formal assessment available) was even more challenging, with few contemporary records existing from either state. All three of these states contain large amounts of potentially suitable habitat, but the vast majority of that wetland has never been surveyed in any meaningful capacity for Spotted Turtles.
This lack of available data challenges not only conservation and management of Spotted Turtles but also fundamental assessments of the species’ status in the southeast. Based on available data the species appears to be sparsely distributed in this region. The main goal of this work was to identify whether or not this was actually the case.
Deploying a Standardized Sampling Protocol
Working on projects funded by the U.S. Fish and Wildlife Service, the Department of Defense, and a large, multi-state Competitive State Wildlife Grant, we conducted extensive surveys for Spotted Turtle across Florida, Georgia, and South Carolina from 2018–2021. Most of this work was supported by the Eastern Spotted Turtle Working Group whose members were also surveying for turtles in other parts of the range. We deployed a standardized protocol that combined trapping surveys and Visual Encounter Surveys, typically implemented across week-long survey periods.
During each sampling week, we identified 1–4 spatially constrained areas that covered potentially suitable wetland habitat. We placed 5–10 traps within each survey area and completed up to 3 visual surveys over the course of a week. We identified potentially suitable wetland habitats through a combination of site knowledge, satellite imagery, and other available data (e.g., the National Wetlands Inventory). Over multiple field seasons, the wetlands visited during this project were highly variable, ranging from small, isolated wetlands to expansive floodplain forests. We occasionally made modifications to the standardized protocol, including deploying a higher density of traps and conducting visual surveys over a large area.
We used our sampling data to estimate how likely the standardized survey methodology was to detect a Spotted Turtle (assuming it was in the survey area) and how likely Spotted Turtles were to occur in survey wetlands. Furthermore, we compared the success of trapping efforts between sites that were surveyed for the first time and sites that were part of long-term monitoring efforts.
What Did We Find?
Over 3 survey seasons (2018, 2019, and 2021), we surveyed a total of 56 sites, including 23 in Florida, 20 in Georgia, and 13 in South Carolina. We sampled 51 sites that had never been surveyed for Spotted Turtles before and 5 long-term monitoring sites (2 in Florida, 2 in Georgia, and 1 in South Carolina). Across all sampling, we conducted 5,703 trap nights (one trap left in the water for one night) and 891 Visual Encounter Surveys. Across the 51 sites surveyed for the first time, we observed Spotted Turtles at 8 sites (1 in Florida, 4 in Georgia, and 3 in South Carolina). We also observed Spotted Turtles at 3 additional sites on roads or during scouting visits (1 in Georgia and 2 in South Carolina). This brings the total number of occupied sites to 11 (21.6% of all new sites). Over the same time period, Spotted Turtle were observed on 20 of 25 (80%) week-long surveys at long-term monitoring sites.
Across all survey efforts, we captured a total of 176 individual Spotted Turtles (37 in Florida, 118 in Georgia, and 21 in South Carolina) on 407 occasions. However, the vast majority (373; 91.6%) of all capture occasions were recorded at the 5 long-term monitoring sites. We encountered more than 5 individual turtles at just a single new survey site, and detections of Spotted Turtles at 7 new sites were made from just a single individual. Finally, a higher density trapping effort did appear to increase captures, while expanded visual surveys in Florida did not.
Our data analysis indicated that both detection probability (0.19–0.20) and occupancy probability (0.12) were low at sites that had not been previously surveyed for Spotted Turtles. However, detection probability was much higher (0.47) at long-term monitoring sites. Detection probability tended to decrease as water temperatures warmed in late spring and early summer, and many preferred Spotted Turtle habitats began to dry out towards the end of the survey season.
Conservation Implications for Spotted Turtles
We conducted extensive surveys for Spotted Turtles across three southeastern states over multiple survey seasons. At a coarse scale, Spotted Turtles are undoubtedly widespread in this region, occurring in a variety of wetland types across many river drainages. However, our survey efforts strongly indicate that they are not present in most wetlands. Instead, they prefer shallow, often ephemeral, floodplain swamps that can be hard to locate in the field. Even when Spotted Turtles were present at survey sites, they were often difficult to detect, with few turtles captured in most surveys.
There are several key points worth highlighting from these efforts:
- Surveys at long-term sites were generally effective at locating turtles using the same methodology deployed at other sites. The challenge in the southeast is locating the particular wetlands being used by Spotted Turtles.
- Much of our sampling effort at new sites was informed by historic Spotted Turtle records. A lack of captures at such sites suggests that Spotted Turtles can shift their distribution over time or that populations have declined in some areas.
- At many sites where we documented Spotted Turtles, only a single individual was captured. Detection of a single individual provides limited information about the status or distribution of the overall population. Additional survey effort is needed at such sites.
- At one new site, surveys failed to detect Spotted Turtles in 2018 but were successful in 2019 when surveying different wetlands on the same property.
Taken together, these examples highlight that it can be exceptionally difficult to locate wetlands with Spotted Turtle populations. Multiple site visits, follow-up surveys, higher survey effort per survey, and short-term telemetry studies are needed to provide meaningful metrics describing population demography or space use, even at relatively coarse scales. Furthermore, survey efforts for Spotted Turtles in the southeast are hampered by a short survey season (typically only 3–4 months) and reliance on ephemeral wetlands that are often dry for large portions of the year.
While challenging and often frustrating, these survey efforts unquestionably increased our knowledge about the distribution of Spotted Turtles in the southeast. Populations were identified on several properties that can now be included in site-specific management plans. Such efforts are needed as we observed many wetlands that had experienced significant hydrologic modifications. Finally, we are currently working on a second multi-state Competitive State Wildlife Grant focused on Spotted Turtle conservation. The goal of this project is to advance Spotted Turtle conservation in the southeast by expanding on the work described here. We are excited to provide additional insights into Spotted Turtle conservation and management throughout the southeast at the conclusion of the current project.
The research discussed here was recently published in the journal Northeastern Naturalist as part of a special issue focusing on the Biology and Conservation of Emydine Turtles. The full publication can be viewed here.
Literature Cited
Berry, J. F., and C. S. Gidden. 1973. The Spotted Turtle in Florida and southern Georgia. Florida Scientist 36:198–200.
Chandler, H. C., B. S. Stegenga, Z. A. Cava, A. Colton, M. T. Holden, D. Hutto Jr, T. M. Wantman, and J. D. Mays. 2024. Ghosts of the swamp: Challenges associated with surveying for Spotted Turtles (Clemmys guttata) in the southeastern United States. Northeastern Naturalist 31:C1–C16.
Meylan, P. A. 2006. Clemmys guttata – Spotted Turtle. Chelonian Research Monographs 3:226–234.
Stevenson, D. J., J. B. Jensen, E. A. Schlimm, and M. Moore. 2015. The distribution, habitat use, activity, and status of the Spotted Turtle (Clemmys guttata) in Georgia. Chelonian Conservation and Biology 14:136–142.
