The Striped Mud Turtle was described by Garman (1891) as Cinosternum baurii from individuals collected in brackish water ponds in Key West, Florida. Stejneger (1925) recognized individuals from the upper Florida Keys as Kinosternon bauri palmarum. Uzzell and Schwartz (1955) recognized K. baurii baurii as the nominal form restricted to the lower Florida Keys, and K. b. palmarum as the subspecies found in the upper Florida Keys and throughout the mainland peninsula. Iverson (1978) synonymized K. b. baurii and K. b. palmarum. Molecular studies also have failed to indicate uniqueness of the Florida Keys subpopulations (Karl and Wilson 2001, Wilson and Karl 2001). Currently, no subspecies are recognized (TTWG 2021).

Hurtado-Gómez et al. (2024) analyzed phylogeographic structure and taxonomic limits within the genus Kinosternon that demonstrated deep intrageneric divergences; they proposed the recognition of three subgenera: Kinosternon, Cryptochelys, and Thyrosternum. The subgenus Thyrosternum was found to include K. baurii, K. durangoense, K. flavescens, K. steindachneri, K. stejnegeri, and K. subrubrum. TTWG (in press) agrees with this proposed taxonomy.

Kinosternon baurii occupies nearly 100,000 sq. km over a wide latitudinal range, but it is most abundant in south Florida. The number of mature individuals distributed throughout the species’ range is unknown but is probably substantially >10,000. Widespread population declines have not been documented, but climate change is predicted to cause a substantial (81–95%) decline of suitable habitat by 2050. Illegal collection for the pet trade is an emerging threat that could cause severe declines, especially in Florida. Little is known about the status of populations across the species’ range. Kinosternon baurii was previously listed as Least Concern (LC) (van Dijk 2011) and currently does not meet any of the criteria to be listed as Vulnerable. However, recent exploitation for the pet trade and projected declines in suitable habitat due to climate change indicate that this species is likely to reach the threshold of a ≥30% reduction in population size over the next 2–3 generations and potentially qualify as Vulnerable. Based on our analyses and assessment of available data on status and population trends, we conclude that K. baurii is close to qualifying for or is likely to qualify for a threatened category in the near future and, as such, meets the criteria of Near Threatened (NT A3cd+4cd) based on projected population declines of ca 20–25% over the next 3 generations (45 years) or estimated 20–25% ongoing declines over the last one generation (15 years) and projected for the next two generations (30 years).

The Striped Mud Turtle, Kinosternon baurii, is found almost exclusively in the lowlands of the Atlantic Coastal Plain from Delaware (northernmost record from Kent County) south through Virginia, North Carolina, South Carolina, Georgia, and the Florida peninsula, extending through the islands of the Florida Keys (Big Pine, Big Torch, Cudjoe, Johnston, Key Biscayne, Key West, Little Torch, Middle Torch, No Name, Ramrod, Saddlebunch, Stock Island, Summerland) (Johnston et al. 2021, TTWG 2021). In North Carolina, it also occurs on the Piedmont (e.g., in Franklin and Wake Counties; Palmer and Braswell 1995) and on Bodie Island (Dare County; Gaul and Mitchell 2007). In Georgia, this species is also found on the Piedmont and only on Cumberland Island among the barrier islands (Laerm et al. 2000, Shoop and Ruckdeschel 2006, Moulis and Stevenson 2008, Brashear and Brown 2016) in addition to well-inland portions of the Coastal Plain (Stevenson et al. 2021). In Florida, its range extends west through the Florida panhandle to the Apalachicola River and then to the upper Chipola River in Jackson County (Iverson and Etchberger 1989, Ewert et al. 2004b, Krysko et al. 2011, Suarez and Mays 2019). One individual was reported from the upper reaches of the Choctawhatchee River in extreme southeastern Alabama (Guyer et al. 2015). Despite the absence of published documentation of K. baurii in Maryland, suitable habitat occurs across the border from nearby Delaware populations. The estimated historical indigenous range (area of occupancy, AOO) of K. baurii was 356,606 sq. km, with an estimated historical indigenous extent of occurrence (EOO) of 838,471 sq. km (TTWG in press). Butler et al. (2016) estimated that the current total area predicted to have >50% probability of suitable conditions (AOO) is 97,886 sq. km, not including the area occupied in Delaware.

Kinosternon baurii is considered widespread and still fairly common in Florida despite few published studies of population ecology (Suarez and Mays 2019). In northern Florida, it was the least abundant of the 10 freshwater turtle species captured by Johnston et al. (2016) in spring-fed and blackwater reaches of the Santa Fe River. In a network of ponds and small creeks on a golf course <10 km north of the Santa Fe River, K. baurii was the second most abundant of six turtle species captured during 2018–2020 (G.R. Johnston, unpubl. data).

In central Florida, K. baurii was the least abundant of three kinosternid species captured by Bancroft et al. (1983) in Lake Conway (Orange County). It was the most abundant of three kinosternid species captured by Enge and Wood (1999–2000) in drift fence arrays in mesic flatwoods, hydric hammock, and basin swamp habitats in Hernando County. Stemle et al. (2020) estimated 81 adults per hectare and a male to female sex ratio of 1:2.2 in restored wetlands in Polk County.

In southern Florida, K. baurii is the most common kinosternid, inhabiting marshes, sloughs, ponds, lakes, canals, and ditches (DeSola 1935, Duellman and Schwartz 1958, Wilson and Porras 1983, Meshaka et al. 2000, Johnston et al. 2008, Meshaka and Layne 2015). Dunson and Mazzotti (1989) reported that K. baurii was common in freshwater habitats in the upper Florida Keys along US Highway 1. In the lower Florida Keys, the species is found in freshwater or brackish ponds that have salinities below 15 ppt (Dunson 1981). Mays and Enge (2016) captured turtles in the Florida Keys in water ranging in salinity from 1 to 10 ppt. Dense populations in the lower Florida Keys were found in artificially constructed mosquito control ditches, which tend to retain water longer than natural temporary ponds (Dunson 1992). Dunson (1981) estimated the size of populations on Summerland Key (219–274 individuals) and Johnston Key (42–52 individuals) based on fieldwork in 1979–1980. Mays and Enge (2016) captured 62 K. baurii on Big Pine Key during 2015–2016 and estimated that 34 individuals (95% confidence interval 20–61) inhabited a 9-ha section of the central marsh. Estimated annual population growth (lambda) in the central marsh was 0.91 (95% confidence interval 0.84–0.98), suggesting a declining population. Mays and Enge (2016) also reported that five trap nights were required to detect turtles in occupied wetlands. Although described from Key West (Garman 1891), Carr (1940) reported he was unable to find any individuals there. Garman (1891) noted that “several collectors have secured specimens in Key West,” which suggests that K. baurii may have been common there at one time.

Little is known about population sizes or trends of K. baurii north of Florida. In southeastern Virginia, this species is widely distributed among mainstem river, tributary, and millpond habitats in the Blackwater River drainage, where it was the second most abundant of seven turtle species trapped by Norman and Mitchell (2014). At the Savannah River Site in South Carolina, K. baurii is the least abundant of three kinosternid species (Gibbons and Semlitsch 1991). The current population trend is unknown across the species' range, but a severe decline may be occurring in south Florida because of illegal collection for the pet trade.

Kinosternon baurii typically inhabits shallow, lentic bodies of freshwater, but can be found in a wide variety of habitats, including swamps, wet prairies, ponds, streams, rivers, and brackish water (Neill 1958, Ashton and Ashton 1985, Gibbons and Semlitsch 1991, Mitchell 1994, Palmer and Braswell 1995, Wilson et al. 2006, Moulis and Stevenson 2008, Beane et al. 2010, Camper 2019, Suarez and Mays 2019, Johnston et al. 2021). Kinosternon baurii is the most terrestrial kinosternid throughout most of its range (Johnston et al. 2021). Movements on land tend to be associated with rainfall (Wygoda 1979, Wilson et al. 1999, Meshaka and Blind 2001). However, individuals in the lower Florida Keys move onto land and use terrestrial retreats when ponds dry or become too saline (Dunson 1992). Nesting females in central Florida may travel several hundred meters (mean = 134.9 m; range = 62–274) from water to oviposit in upland habitats (Mushinsky and Wilson 1992, Wilson 1998, Wilson et al. 1999), which is the farthest of any known kinosternid nesting movements (Steen et al. 2012). After oviposition, central Florida females may move a few meters from the nest and bury themselves under soil or leaf litter for up to 35 days (Wilson et al. 1999).

Kinosternon baurii is omnivorous; its diet includes palmetto seeds, leaves, algae, worms, aquatic insect larvae and adults, molluscs, crayfish, fish, and small vertebrates (Einem 1956, Wilson et al. 2006, Moulis and Stevenson 2008, Ernst and Lovich 2009, Johnston et al. 2015). Striped Mud Turtles have also been observed scavenging on small mammal carcasses and Cuban Treefrogs (Duellman and Schwartz 1958, Donini 2018).

Nesting occurs in all months in Florida but is least frequent during the hottest summer months (Iverson 1979, Mushinsky and Wilson 1992, Wilson et al. 1999, Meshaka and Blind 2001, Ewert and Jackson 2005). Little is known about nesting phenology north of Florida, but the nesting season is likely more restricted. Camper (2019) noted finding a road-killed female with shelled eggs on 5 September in South Carolina. In North Carolina, gravid females have been found during April, July, August, and October (Palmer and Braswell 1995).

Female K. baurii typically lay 1–3 clutches of eggs per year in Florida (Lardie 1975; Iverson 1978, 1979; Meshaka 1988; Wilson et al. 1999; Meshaka and Blind 2001; Wilson et al. 2006), but Iverson (1979) suggested that females in northern Florida could possibly produce up to six clutches. Little is known about annual clutch frequency farther north. Clutch size ranges from 1–7 eggs, with some suggestion that clutch size is greater in the north than in the south (Nicol 1970, Mitchell 1994, Ewert and Jackson 2005, Ernst and Lovich 2009).

Laboratory incubation times normally range from 97–143 days (Einem 1956, Lardie 1975, Iverson 1979). Because the egg stage of this species is known to exhibit embryonic diapause (early arrested development; Ewert 1991, Ewert and Wilson 1996) and embryonic estivation (late embryonic dormancy; Ewert 1985), incubation times in the field may be considerably longer than those in the laboratory. Most embryos of this species diapause at cool temperatures between 22.5 and 24°C and commence active development within 5–9 days at 30°C (Ewert 1991, Ewert and Wilson 1996). In central Florida, eggs laid in fall and winter exhibit diapause and then resume embryonic development in spring (Wilson et al. 1999). These eggs overlap the development of eggs laid in spring, which do not diapause. Incubation time from the end of diapause to hatching ranged from 120–150 days. Thus, eggs oviposited in fall may remain in the nest cavity for nearly one year before hatching.

Kinosternon baurii exhibits temperature-dependent sex determination, but patterns are different among Panhandle and Peninsula populations in Florida (Ewert et al. 2004a). On the Peninsula, all female offspring are produced at hot temperatures (≥29°C), nearly all male offspring at medium temperatures (25–27°C), and mixed sex offspring at cool temperatures (≤24°C). However, in the Panhandle, males predominate at lower temperatures (≤24°C), females at higher temperatures (ca 30°C), and nearly equally at temperatures from 26–27°C (Ewert et al. 2004a).

Hatchlings have the following dimensions: 15–25 mm straight-midline carapace length (SCL), 15.45–22 mm maximum plastron length, 14.0–19.0 mm carapace width, 10.9–18.2 mm shell depth/height, and mass of 2.0–3.9 g (Einem 1956, Nicol 1970, Lardie 1975, Iverson 1979, Palmer and Braswell 1995, Johnston et al. 2021). Adult body size varies geographically, especially among populations in different habitats (Johnston et al. 2019). The SCL of the largest known female and male were 13.8 cm and 11.5 cm, respectively (Ewert and Jackson 2005, Johnston et al. 2019).

Little is known about age at maturity. Females mature in 5–6 years at 75–80 mm SCL in northern Florida (Iverson 1979), but geographic variation is likely. Generation length is also poorly understood but is probably ≥15 years in northern Florida. Lechowicz et al. (2011) estimated generation length at 17.5 years in the lower Florida Keys. Maximum lifespan is not well known. The oldest known wild female was ≥16 years old; the oldest known wild male was ≥14 years old (Johnston et al. 2021). Pope (1939) discussed a female that was a full-grown adult when captured and subsequently lived approximately 25 years in captivity. This same individual, also noted by DeSola (1935) and Mathewson (1955), ultimately lived a total of 49 years, seven months in captivity (≥54 years old).

In Virginia, Striped Mud Turtles are vulnerable to habitat loss, particularly of small ephemeral wetlands (Mitchell 1994). The lower Florida Keys populations are vulnerable because of intensive development, especially of the hammock pond habitat that is essential for the survival of the species, as well as road mortality and nest predation by subsidized predators, such as raccoons (Lazell 1989, Suarez and Mays 2019). Although populations exist on some protected islands of the lower Florida Keys, many large populations are on private lands. Another problem facing the Striped Mud Turtle in the lower Florida Keys is the filling of mosquito-control ditches to accommodate management recommendations for the endangered Key Deer. Dunson (1992) found these artificial ditches to support relatively dense populations of Kinosternon baurii. Saltwater intrusion and sea level rise are also expected to affect the lower Keys population.

Trade has been a problem for this species in Florida, with 1,417 individuals reported collected for the pet trade from 1990–1994 (Enge 2005). Although collection limits (one turtle per person per day from the wild for non-commercial use) were imposed in 2009, illegal trade continues to be a problem in Florida, with as many as 200 turtles sometimes collected in a single day (Suarez and Mays 2019). According to the Florida Fish and Wildlife Conservation Commission, Striped Mud Turtles were among >4,000 turtles illegally collected to be sold to Asian markets over a 6-month period in 2018–2019. The turtles were primarily collected in Lee County, but poachers expanded their activity to other parts of Florida as populations became depleted. United States Fish and Wildlife Service Law Enforcement Management Information System data indicate that 3% of the turtles exported from Florida during 2016–2020 were K. baurii (15,273), a number nearly 15x higher than that reported by Enge (2005) in a similar four-year span. These data may be conservative because Van Barrow (Florida Fish and Wildlife Conservation Commission) stated that 46,305 K. baurii were exported during 2016–2020 (Turtle Survival Alliance Annual Symposium on Conservation and Biology of Tortoises and Freshwater Turtles, August 2022). In 2022, a federal investigation documented the illegal acquisition and sale of more than 3,500 freshwater turtles collected in Florida from April 2017 to April 2019. Most of the confiscated turtles were K. baurii. Turtles were confirmed to be wild-collected while misleadingly labelled as captive-bred individuals (United States Attorney’s Office 2022).

Road mortality is another substantial threat to this highly terrestrial species. Striped Mud Turtles made up the largest percentage of turtle species found as road kills on a 3.2 km stretch of road in Alachua County, Florida (Smith and Dodd 2003). In the Everglades, American Crows (Corvus brachyrhynchos) cause significant mortality to Striped Mud Turtles as the turtles attempt to cross roads (C. May pers. comm., May 2023). Crows may be drawn to turtles killed or injured along the highways, then opportunistically target turtles crossing the road, much as Ravens (Corvus corax) target small Desert Tortoises (Gopherus agassizii) in the southwestern United States.

Using a maximum entropy approach to model the effects of climate change on K. baurii, Butler et al. (2016) concluded that areas with suitable climatic conditions for K. baurii are expected to decline substantially over the next few decades. The best model projected a mean annual temperature of 22–24°C, a mean temperature during the wettest quarter of 27–28°C, precipitation during the wettest quarter of 51–64 cm, and precipitation during the warmest quarter of 49–62 cm. Given these conditions, populations in the southern portions of the species’ range will most likely be adversely affected, with the distribution expected to shift northeastward. The problem is that the availability of suitable habitat decreases northward, putting this species in jeopardy. Butler et al. (2016) projected that 81–95% of suitable habitat would decline by 2050. These results agree with Ihlow et al. (2012) who predicted that the suitable range of K. baurii would virtually disappear in the 21st century.

Striped Mud Turtles are popular pets. Their small size and striking colors are factors driving their increasing popularity (A. Pierlioni, TheTurtleRoom, pers. comm., June 2023). Specifically, a high yellow phenotype dubbed “Blonde” or “Golden” often associated with south Florida (but seen in other populations) has become very popular both domestically and internationally (May 2008; A. Pierlioni, pers. comm., June 2023). Darker or patternless individuals from Virginia and the Florida Keys are also popular (A. Pierlioni pers. comm.). Captive breeding contributes little to the pet trade, perhaps due to the long incubation times and small clutch sizes (A. Pierlioni pers. comm.). Availability of wild-caught individuals is also cited as a possible reason behind the lack of interest in established captive breeding colonies.

A press release by the United States Attorney’s Office (2022) detailed a confiscation of wild-caught turtles (including Kinosternon baurii) that were destined for both domestic and international sale. Current 2023 domestic prices for standard K. baurii phenotypes range from 40–150 USD for hatchlings to 100–200 USD for adults with captive-bred designations domestically in the United States, and a company based in Hong Kong is seeking 5,000 specimens of Kinosternids, with K. baurii included in the request (G.R. Johnston pers. comm.).

Kinosternon baurii is not federally protected under the United States Endangered Species Act of 1973. It was included in CITES Appendix II in 2023 as Kinosternon spp. The lower Florida Keys population was listed by the Florida Fish and Wildlife Conservation Commission as Threatened in 1975 and subsequently elevated to Endangered status in 1979. Its status was later returned to Threatened until it was delisted in 2017 because it did not meet the IUCN definition of an isolated population. Kinosternon baurii is currently included in the Florida Fish and Wildlife Conservation Commission’s Imperiled Species Management Plan. In Florida, no one may sell K. baurii taken from the wild. Take is limited to one turtle per person per 24-hr day from the wild for non-commercial use. The transport of more than one turtle per day is prohibited, unless the transporter has a license for sale or exhibition of wildlife, aquaculture certification from the Department of Agriculture and Consumer Services, or documentation that their turtles were legally obtained (proof of purchase required). Striped Mud Turtles can only be taken by hand, dip net, minnow seine, or baited hook. Collection of eggs is prohibited.

In Georgia, no more than 10 freshwater turtles (any combination of species) may be possessed without a commercial turtle permit. In South Carolina, K. baurii was listed as a species of concern prior to new laws implemented in 2020 (Camper 2019). All native turtles in South Carolina are now protected from take or possession for commercial purposes; the personal possession limit for K. baurii is five. In North Carolina, mud turtles may be collected (trapped) and eaten if fewer than four turtles are collected in a season. If five or more turtles are to be trapped, a license must be obtained from the Wildlife Resources Commission. With a permit, individuals may collect no more than 10 turtles from the family Kinosternidae per day and no more than 100 per calendar year. In Virginia, it is illegal to sell or purchase any turtle species that is native or naturalized, but they may be given away and kept as pets, as long as the person has no more than five individuals of that species in captivity. In Delaware, commercial collection of native turtles requires a permit; one individual of each turtle species may be possessed without a permit.

This species is known to occur in protected areas such as Everglades National Park, Biscayne National Park, Big Cypress National Preserve, Key Deer National Wildlife Refuge, and the Savannah River Site, but it probably occurs in many other national, state, and local protected areas with appropriate habitat within its range.

A thorough status survey is needed throughout the range of this species, particularly north of peninsular Florida. Long-term monitoring of populations throughout the species’ range is needed. In the lower Florida Keys, efforts should be made to determine the proportions of Striped Mud Turtles residing on public and private lands. Commercial collection of this species for the pet trade should be abolished. Habitat protection should include aquatic habitats and surrounding uplands, ensuring a terrestrial buffer zone at least 200 m wide. Future studies should examine geographic variation in terrestrial habitat use. Conservation measures taken in Florida should also be applied throughout the species’ range. Conservation laws must be enforced.