Eastern mud turtle hatchlings have a red-orange bottom shell (plastron); the scientific name of the species refers to this characteristic (Gibbs et al. 2007).
The eastern mud turtle is the rarest turtle species in New York. The species is rare in New York because of its limited distribution, small number of populations, and low numbers of individuals. It is limited to Long Island and nearby islands, which represent the extreme northeastern edge of its U.S. range (Ernst and Barbour 1972). Since 1990, eastern mud turtles have been documented at only seven wetland complexes in the state (New York Natural Heritage Program 2010). The largest and most secure population contained approximately 68 marked turtles in 1996 (Larese-Casanova 1997; Soule 1997), the next largest is currently estimated at 35 individuals, and the rest appear to be much smaller or have been insufficiently surveyed (Soule and Lindberg 2008).
Since 1984, researchers have documented population declines at several sites in New York. In addition, since 1994, researchers have not found any new populations in the state. In 2008, researchers determined that, among the few populations known to exist, one population most likely was extirpated, and another was on its way to extirpation. At the population on its way to extirpation, in 1989 researchers captured approximately 20 adult eastern mud turtles, in subsequent years they documented a continual decline in the population, and in 2001 they captured only two adults (Soule and Lindberg 2008). Most of the other populations in the state appear to be small or have been insufficiently surveyed.
An overall decline in the distribution and abundance of eastern mud turtles in New York is likely, although hard data are lacking. One specimen was collected in Westchester County in 1884, but currently no populations are known to exist in Westchester County or any other county in the Lower Hudson Valley (New York Natural Heritage Program 2010). This represents a range contraction of approximately 73 km (45 mi). The rapid development on Long Island has increased mortality to turtles on roads and has destroyed or degraded wetland habitats and upland nesting and hibernation habitats. This has reduced the distribution and abundance of eastern mud turtles in New York, which constitutes the northeastern edge of the species' range (Gibbs et al. 2007).
The rapid development of Long Island and Staten Island poses numerous threats to eastern mud turtles. The draining of wetlands for urban and industrial development reduced the amount of wetland habitat, the development of uplands adjacent to wetlands reduced the amount of suitable upland nesting and overwintering habitat, and the construction of roads fragmented the landscape and resulted in increased road mortality (NYS DEC 2005). These factors reduced the distribution and abundance of eastern mud turtles in New York, which constitutes the northeastern edge of the species' range (Gibbs et al. 2007). Currently, the few remaining viable or potentially viable eastern mud turtle populations in the state are located on protected lands (New York Natural Heritage Program 2010). Road mortality can be particularly detrimental to turtles, which are slow to mature and therefore depend on high levels of adult survivorship to maintain populations. Turtles killed by vehicles represent a significant loss to populations, and road mortality can be an especially significant threat for turtle species that are mobile and terrestrial or semiterrestrial (Gibbs and Shriver 2002). In New York, eastern mud turtles have been documented to cross roads when traveling between wetlands, and when traveling between wetlands and upland nesting and overwintering sites. There have been several accounts of eastern mud turtles killed on or near roads in New York (Cavanagh and Hassler 1990; New York Natural Heritage Program 2010). A related threat associated with urbanization is the construction of road structures such as Belgian block curbs, drainage grates, and drywells in newly created roads, which act as barriers to turtle dispersal, trapping turtles in roadbeds and preventing them from crossing roads. Several new roads with Belgian block curbing and drainage grates were constructed near one eastern mud turtle population in New York during the winter of 1988-1989. One of these roads bisects a known eastern mud turtle winter dispersal site. The configuration of the curbing on that road makes it an impassable barrier for eastern mud turtles (Cavanagh and Hassler 1990). The overabundance of raccoons, which are often called "subsidized predators" because their populations tend to increase following suburban development, may also be a threat (Marchand et al. 2002). At one eastern mud turtle population in the state, researchers have found numerous depredated eastern mud turtles and one eastern mud turtle with an injury likely caused by a predator, and they have found that numerous turtle traps that they have set have been routinely disrupted by raccoons (Soule and Lindberg 2000). One year, at another eastern mud turtle population in the state in an area experiencing suburban development, researchers found that all located turtle nests were depredated (Cavanagh and Hassler 1990). The largest eastern mud turtle population in the state is on a small island on which raccoons and other mammalian predators are absent (Soule 1997). Additional potential threats include the spread of the invasive plant species Phragmites in wetlands the turtles occupy and consequent Phragmites control efforts (Soule and Lindberg 2008); hydrological changes in wetlands the turtles occupy (NYS DEC 2005); water quality reductions caused by runoff containing pollutants such as oils, road salts, insecticides, and pesticides (NYS DEC 2005); collection for the illegal pet trade, which exploits adults necessary for sustaining populations (NYS DEC 2005); the use of lawn mowers in areas the turtles traverse (Cavanagh and Loop 1989); and rises in sea level that may negatively affect turtles in coastal areas on barrier islands (New York Natural Heritage Program 2010).
Currently, all eastern mud turtle populations in New York considered viable or potentially viable are located on protected land. Management recommendations for the populations are site-specific. However, actions that would benefit several populations include: 1) controlling subsidized predators, particularly raccoons and opposums, from the beginning of May to August (Soule and Lindberg 2008; N. Soule, personal communication), 2) using controlled burns and/or other methods of opening the canopy (e.g., mowing or selective vegetation removal) every five to ten years, or as needed, to provide suitable open and sandy upland habitat for nesting and incubation of eggs (Cavanagh and Hassler 1990; Soule and Lindberg 2000; Mitchell et al. 2006); before conducting clearing activities, attempts should first be made to locate nests, since eggs may overwinter, and eggs could be scorched or crushed during clearing activities (Cavanagh and Hassler 1990), 3) leaving some cover, particularly sapling trees, in all cleared areas, to allow turtles to hide from potential predators during the day, since the turtles frequently have been found to burrow at the base of sapling trees during the day (Cavanagh and Loop 1989; Cavanagh and Hassler 1990), 4) leaving relatively undisturbed forest habitat within landscapes occupied by the turtles, since the turtles have been found to select these habitats and often overwinter in areas with herbaceous vegetation and woody debris (Harden et al. 2009), 5) using any wheeled vehicles and conducting any vegetation control work only during the late fall and winter in occupied areas (Mitchell et al. 2006), 6) establishing buffer zones around occupied wetlands and conducting work of any kind within 300 ft of these wetlands only by hand during the entire year (Soule 1997), 7) planning the removal of Phragmites from occupied wetlands in ways that may benefit, or at least minimize negative impacts to, the turtles, taking into account the movements and habitat needs of the turtles, and timing Phragmites management with studies in the area; perhaps Phragmites could be slowly removed over several years while the turtles are closely monitored (Soule 1997; Mitchell et al. 2006; Soule and Lindberg 2008), 8) reducing the speed limit in key areas and placing "turtle crossing" signs to warn motorists of the presence of the turtles (Cavanagh and Hassler 1990; Mitchell et al. 2006), 9) encouraging workers who travel frequently near occupied wetlands to look for turtles crossing roads (Soule 1997), 10) pitching block curbing at a 45 degree angle, or removing several blocks every few feet, and altering drainage grates to ensure turtles do not become trapped in roadbeds or fall through grates (Cavanagh and Hassler 1990), 11) modifying any additional barriers (e.g., culverts, ditches) in such a way that ensures turtles do not encounter any impassable barriers to movement (Cavanagh and Loop 1989; Mitchell et al. 2006) throughout a buffer zone that extends 0.5 mile from occupied wetlands, which is the longest distance an eastern mud turtle has been documented to move in New York (Soule 1997), and 12) minimizing the use of pesticides and fertilizers near occupied wetlands (Cavanagh and Loop 1989; Mitchell et al. 2006). Additionally, turtle nests can be located and protected from predators such as raccoons by placing a wire cover over each nest, constructed so that turtle hatchlings can exit, although this is labor intensive. Also, chimney caps, strict garbage regulations, and enforcement of laws that require pets to be kept on leashes can be used to further mitigate predation pressure (Cavanagh and Loop 1989; Mitchell et al. 2006).
Research is needed to assess the impact of predation on eastern mud turtle populations. The use of artificial nests might be useful in investigating this impact (Marchand et al. 2002). If data show predators are having a large negative impact on populations, predator control research would be useful. In states with more populations than New York, more robust research could be conducted. Several occupied wetlands, preferably within protected areas such as national wildlife refuges, could be chosen to allow for a study design with several pairs of "treatment" and "control" wetlands. At "treatment" wetlands, predators could be controlled for five to ten years. Population levels at "treatment" wetlands could be monitored for at least ten years afterward and compared to population levels at "control" wetlands (Soule and Lindberg 2000; Soule and Lindberg 2008). Reseach is also needed to determine the effects of Phragmites control efforts on eastern mud turtle habitats and populations (Soule and Lindberg 2008).
Eastern mud turtles live in freshwater or brackish wetlands and the undeveloped sandy vegetated uplands that surround them. They prefer wetlands that are shallow and quiet, with a soft bottom and emergent vegetation. These wetlands include marshes, small ponds, water-filled ditches, creeks, and swamps. On Long Island and adjacent islands, the turtles usually occupy brackish marshes and ponds dominated by giant reed grass (Phragmites australis). The surrounding undeveloped sandy uplands are a critical component of suitable habitat, since they provide areas that are critical for nesting and overwintering (Soule and Lindberg 2008).
Eastern mud turtles are limited to Long Island, Staten Island, and small nearby islands, which represent the northeastern edge of the species' U.S. range (New York Natural Heritage Program 2010). Two eastern mud turtles have been reported from Orange County since 1990, but the reports are currently considered leads since the origins of the turtles are unknown, and the turtles could be releases.
Eastern mud turtles are found in the eastern and southern U.S., from New York and Indiana west to Oklahoma and south-central Texas (Ernst and Barbour 1972).
Adult eastern mud turtles have a light or dark top shell that is oval and smooth, a dark bottom shell with two distinct hinges, a dark brown head with yellow blotches, and a tail with a hornlike appendage at the tip (Gibbs et al. 2007).
Eastern mud turtles have a smooth, unkeeled, oval top shell (carapace) that can be brown, yellowish to olive, or black. Although most freshwater turtles have 12 marginal scutes on each side of the carapace, eastern mud turtles have 11. The bottom shell (plastron) is yellow to brown, and it has two well-developed hinges. Usually the head is dark brown with yellow mottling. Both males and females have nail-tipped tails. Males have much larger tails than females, and the cloacal opening on males is located beyond the rear margin of the carapace. Males also have a patch of rough scales on the inner surface of their rear legs. Carapace lengths are often 3-4 in. (7-10 cm) and can reach a maximum length of 4.9 in (12.4 cm). Hatchlings are 0.7-1.1 in (1.7-2.7 cm), and the plastron on hatchlings contains orange mottling (Gibbs et al. 2007). The carapace and skin on hatchlings is dark brown or black. Eastern mud turtles have elliptical, brittle-shelled eggs that are bluish white or pinkish white (Ernst et al. 1994).
Adults and hatchlings look different, but the species is easy to identify at any age.
In New York, eastern mud turtles overwinter in upland areas. They bury into dry sandy hillsides or under leaves, often under bramble or understory, below the frost line, near the edges of wetlands. They have not been found to spend the winter beyond the wetland interface. This terrestrial hibernation behavior is different from that of most other turtle species in New York, which exhibit aquatic hibernation behavior, overwintering at the bottom of wetlands (Soule and Lindberg 2008). Eastern mud turtles emerge from their upland hibernacula as early as mid-March on Staten Island (New York Natural Heritage Program 2010) and between April and late May on Long Island, but they might not enter wetlands until May (Soule 1997). In the spring, they usually spend most of their time at the bottom of wetlands, often retreating in muskrat lodges. Females nest in June, depositing one to eight (usually four or five) eggs in a shallow cavity in sandy soil or vegetative debris near occupied wetlands. In the late spring, the turtles often depart drying wetlands and become surprisingly terrestrial (Gibbs et al. 2007). In the summer in New York, depending on the location and level of drought in any given year, some individuals have been found to spend much time in upland refugia, while others have traveled overland distances of up to 0.5 mi between wetlands (Soule 1997), and still others spend more time in densely vegetated areas of wetlands, including stands of Phragmites up to 10 ft tall. The turtles often head toward upland hibernacula as early as late August/early September (Soule and Lindberg 1993), but they also have been found active in wetlands as late as October (Soule and Lindberg 2008). Eastern mud turtle eggs likely hatch in the late summer, but the hatchlings usually spend the winter in the nest and emerge the following spring/early summer (Nichols 1947; Soule 1997).
Eastern mud turtles are omnivores and typically forage at the bottom of wetlands, searching for crustaceans, aquatic insects, snails, and algae (Gibbs et al. 2007).
Eastern mud turtles are most visible from late May - mid July (New York State Department of Environmental Conservation 2009).
The time of year you would expect to find Eastern Mud Turtle present, active, and reproducing in New York.
Eastern Mud Turtle
Kinosternon subrubrum (Lacepède, 1788)
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This guide was authored by: Andrea Chaloux
Information for this guide was last updated on: June 25, 2019
Please cite this page as:
New York Natural Heritage Program. 2022. Online Conservation Guide for Kinosternon subrubrum. Available from: https://guides.nynhp.org/eastern-mud-turtle/. Accessed December 2, 2022.