The Escambia Map Turtle, Graptemys ernsti, was considered to be part of the Alabama Map Turtle (Graptemys pulchra) complex until it was recognized as a separate species by Lovich and McCoy (1992). Hybridization occurs between G. ernsti and G. barbouri in the Choctawhatchee River drainage of Alabama and Florida (Godwin et al. 2014). Genetic and morphological differences have been noted between the Conecuh/Escambia River, Yellow River, and Pea River subpopulations, but no taxonomic revisions were recommended (Ennen et al. 2016).

We assess Graptemys ernsti as Near Threatened (NT) at this time under criteria A2bc. Its range is small, with an area of occupancy of three watersheds in south Alabama and the Florida Panhandle. Genetic studies have demonstrated that populations in each watershed are divergent, and population estimates for each occupied drainage are needed. Habitat degradation is an ongoing threat with salvage logging of submerged tree trunks and snag removal, stream bank degradation from improper logging activities, water quality degradation from paper mill and wastewater treatment facility. Proposed impoundments would alter natural hydrology. The entire range of G. ernsti is near the Gulf Coast with catastrophic hurricanes and tropical storms periodically sweeping across the watersheds. Severe storms may result in flooding events and the deposition of large quantities of downed trees into low order streams. The impact of these natural events upon G. ernsti populations is unknown, but despite an estimated total population reduction of ca 20% over the last three generations (ca 90–100 years), populations at present appear stable.

The species is popular in the pet trade and while Alabama and Florida have regulations in place to prohibit the commercial collection of these turtles, the regulations can only be enforced with adequate state support. The effect of past overcollection is unknown. Motorized recreational vehicles in and along streams are an unregulated threat. These threats include prop strikes on turtles in rivers with motorized boats and off-road-vehicle (ORV) damage to nesting beaches. Nest predation under natural conditions is high, but with human use of rivers, discarded food may subsidize mesopredators and increase the rate of nest predation. The species was previously assessed in 2011 as Near Threatened (van Dijk 2011).

Graptemys ernsti inhabits rivers and associated tributaries of the Escambia and Choctawhatchee Bays of the Gulf of Mexico (Shealy 1976, Lovich and McCoy 1992, Aresco and Shealy 2006, Lovich et al. 2011, Lindeman 2013, TTWG 2021). These include the Escambia, Conecuh, Sepulga, Shoal, Yellow, and Pea rivers and smaller tributaries such as Patsaliga, Persimmon, and Pigeon creeks. The range of G. ernsti is wholly within the Lower Coastal Plain of Alabama and Florida. Reasonable estimates for the current area of occupancy (AOO) are between 700 and 1,000 linear km of streams, or an estimated AOO of ca 1,400–2,000 sq. km (2 km per river km). The species is known to occupy at least 235 linear river kms in Florida based on recent distributional surveys. The estimated historical indigenous range (AOO) was ca 8,284 sq. km, and the estimated historical extent of occurrence (EOO) was 19,178 sq. km (TTWG in press).

Graptemys ernsti was considered the seventh rarest/commonest Graptemys by P.V. Lindeman (pers. comm. 2009) based on extensive basking surveys. Numbers of animals seen during basking surveys were more numerous compared to the ecologically equivalent G. gibbonsi, ranging from 5–17.5 or higher numbers of animals per km of river, and G. ernsti is apparently the most abundant turtle of the Escambia and Yellow rivers (Aresco and Shealy 2006).

Surveys conducted in Alabama by Godwin (2020) reported mean number of basking G. ernsti from the Conecuh, Sepulga, Yellow, and Pea rivers for the years 2000–2002 and 2018–2020; G. ernsti was the most commonly documented basking turtle during these surveys with the reported mean number of individuals per river km in Table S1 (see Supplementary Information). 

Surveys by Mays (unpubl. data) of a 6.38 river-km section of the upper Escambia from Terrell Landing to Century Landing in July 2016 observed 123 G. ernsti (19.3 turtles/rkm). Ongoing single-pass distributional surveys in Florida (2022–2023) have tallied 1,374 G. ernsti (6.2 turtles/km), compared to 811 other turtle species and another 161 unidentified turtles (Hill, unpubl. data). The counts reported here (see Table S2 in Supplementary Information) likely underestimate relative abundance due to several surveys being negatively affected by inclement weather.

Additional standardized surveys incorporating environmental covariates are needed to demonstrate population trends.

Graptemys ernsti inhabits the main channels of medium-sized to large rivers and creeks, specifically areas with an abundance of freshwater mussels and snags for basking. The species does not or rarely occurs in estuarine habitats (Shealy 1992, Ernst and Lovich 2009). Females nest on large, relatively open sandbars of fine sand (Shealy 1976). Males and juveniles feed mainly on insects, while adult females feed almost exclusively on gastropod and bivalve molluscs, with the introduced Asian clam Corbicula being the females’ primary prey (Aresco and Shealy 2006, Lovich et al. 2011, Lindeman 2013). Females mature at an age of at least 14 (Shealy 1976; more likely 19) years, 21.2 cm carapace length (CL), and can reach a maximum size of 28.5 cm CL by age 23 years (Shealy 1992). Thus, based on female maturation age of 14–19 years, estimated generation time is ca 32 years (Iverson 2024). Males mature at about 3–4 years of age, at or over 80 mm CL, and can attain maximum size of about 13.1 cm CL by age of eight years. Females nest from May through July and produce an average of four (range 1–6) clutches per female per year, each clutch comprising an average of seven (range 6–13) eggs (Lindeman 1999, Aresco and Shealy 2006, Lovich et al. 2011, Lindeman 2013). Eggs average about 38 mm long, 26 mm wide, and 15 g.

Nest predation is variable by location and time but may exceed 95%, mainly from raccoons and fish crows; while these are native species, their populations tend to be increased by human facilitation. Nest and hatchling mortality has been recorded resulting from recreational vehicle use on riverine sandbanks (Aresco and Shealy 2006).

Water quality in the Conecuh and Escambia rivers is at potential risk from catastrophic mishaps at upstream industrial facilities, including a paper mill, a waste water treatment facility and a manufacturing facility, potentially affecting the turtles’ filter-feeding prey and the turtles themselves (Aresco and Shealy 2006).

Potential threats on the future horizon include salvage logging of submerged tree trunks, snag removal for boating purposes, and proposed impoundments and associated water flow changes and sediment loading (Aresco and Shealy 2006).

Graptemys ernsti is in some demand in the global pet trade and persistent collection could impact the species significantly.

Graptemys ernsti was included in CITES Appendix III (United States) in 2006 as Graptemys spp., and in Appendix II in 2023 as G. ernsti. It is in some demand in the global pet trade and persistent collection could impact the species significantly.

Graptemys ernsti previously was assessed in 2011 as Near Threatened (NT) (van Dijk 2011); as G2 (Imperiled) at both global and State level by the Florida Natural Areas Inventory; and as ‘Rare’ by the FCREPA based on its occurrence in just a single drainage basin. Graptemys ernsti is prohibited from most forms of commercial exploitation in Alabama and Florida; Florida allows take of up to two individuals for personal use. Aresco and Shealy (2006) recommended further regulation of personal take in Florida, outlawing basking traps, regulating all-terrain vehicle (ATV) access to riverside areas, and called for collection of baseline data on turtle populations for long-term monitoring, monitoring of water quality parameters, development of pollution spill contingency plans, and due consideration of turtles and ecological values when considering hydrological infrastructure developments.

All broad-headed Graptemys spp. (G. barbouri, G. ernsti, G. gibbonsi, G. pearlensis, and G. pulchra) have been proposed for inclusion as Threatened under the Endangered Species Act (ESA) (Lindeman 1999; Selman and Qualls 2007; USFWS 2021). The genus Graptemys was included in CITES Appendix III (United States) since 2006, and all broad-headed Graptemys spp., including G. ernsti, have been included in Appendix II since 2023.