New York Natural Heritage Program
Eastern Mud Turtle
Kinosternon subrubrum (Lacepède, 1788)

General Description [-]
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).

Identifying Characteristics [-]
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).

Best Life Stage for Proper Identification [-]
Adults and hatchlings look different, but the species is easy to identify at any age.

Behavior [-]
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).

Diet [-]
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 Turtle Images
click to enlarge
The Best Time to See
Eastern mud turtles are most visible from late May - mid July (New York State Department of Environmental Conservation 2009).
Present Active Reproducing
The time of year you would expect to find Eastern Mud Turtle present (blue shading), active (green shading) and reproducing (orange shading) in New York.
Similar Species
  • Common Musk Turtle (Kinosternon odoratum)
    The eastern mud turtle looks similar to the common musk turtle. However, the eastern mud turtle has a bottom shell (plastron) with two well-developed hinges, a dark brown head with yellow mottling, and a nail-tipped tail, whereas the common musk turtle has a highly domed top shell (carapace), a single hinge on the front portion of the plastron, two yellow stripes extending backward from a pointy snout (one above and one below the eye), and fleshy protrusions (barbels) on the chin and throat (Gibbs et al. 2007).