Three-Toed Box Turtle

Characteristics

All box turtles, Terrapene carolina spp., have a bridgeless, bilobed, hinged plastron that allows box turtles to close their shells almost completely! They have a steep margined, keeled, high-domed, rounded carapace with variable markings. Concentric growth furrows can be seen on the carapace, although in some older individuals they become very difficult to see. The upper jaw is slightly hooked. The toes are only slightly webbed.

Species Specifics

The Three-Toed Box Turtle has a tan or olive carapace with darker seams and some vague markings. They also have orange, red and yellow spots on their head and forelimbs.The defining characteristic of this turtle is its toes. It has three toes on its back feet, thus why its known as the Three Toed Box Turtle. Hybrid Three Toed Box Turtles who have been interbred with Common Box Turtles sometimes have four toes instead of three. Sexual Dimorphism: males are larger. Males are slightly larger on average, the posterior lobe of their plastron is concave, and the claws on their hind legs are short, thick and curved. Males also have thicker and longer tails. Females' rear claws are longer, straighter and more slender, and the posterior lobe of their plastron is flat or slightly convex. There are four subspecies of Terrapene carolina in the United States. Terrapene carolina bauri (Florida Box Turtle) lives on the peninsula of Florida. Terrapene c. major (Gulf Coast Box Turtle) ranges from the panhandle of Florida westward along the Gulf cost to eastern Texas. Terrapene c. triunguis (Three-toed Box Turtle) lives in the Mississippi River Valley from northern Missouri southward across southeastern Kansas and eastern Oklahoma into southcentral Texas; and southeastward across western Tennessee and Georgia to the coastal lowlands.

Physical Characteristics

Ecology

Habitat

Open woodlands, pastures and marshy meadows.

Distribution

Exclusively North American, box turtles are found in the eastern United States, ranging from southern Maine to Florida along the East Coast, and west to Michigan, Illinois, eastern Kansas, Oklahoma and Texas. Due to it's popularity as a household pet, Three-Toed Box Turtles are sometimes found far outside their normal geographic range.

Diet

Omnivore. Eats snails, insects, berries, roots, flowers, fish, frogs, salamanders, snakes, birds and eggs. They have also been observed eating carrion: feeding on dead ducks, amphibians, assorted small mammals, and even a dead cow! Young are primarily carnivorous while they grow during their first 5-6 years. While adults tend to be mostly herbivorous, but they eat no green leaves.

Ecological Web

Secondary consumer. They may serve the ecological role of a seed distributor through their eating of berries that contain seeds. They also eat insects.

Activity and Behavior

Activity Pattern

Environmental temperature determines the activity rate of these turtles. Preferred body temperature is between 29 and 38 degrees Celsius. In the heat of the summer T. carolina largely restricts their activity to mornings and after rain. When it gets too hot, they hide under decaying logs and leaves, crawl into mammal burrows, or in mud. In the spring and fall, they may be out foraging during all daylight hours, and they sometimes bask in the sun to get warm. Terrapene carolina are diurnal and scoop out a shallow indentation in which to spend the night. In the northern regions Terrapene carolina go into hibernation in October or November, but further south they remain active later in the year. To hibernate, they burrow as much as two feet deep into loose earth, mud, stream bottoms, old stump holes, or mammal burrows. They return to the same place to hibernate in successive years and sometimes more than one turtle hibernates in the same burrow. They usually emerge from hibernation in April. They sometimes wake up and find a new burrow (hibernacula) on warm days in the winter.

Behavior

Social Behavior

Reproductive Behavior

Polygynandrous (promiscuous). The mating season begins in the spring and continues throughout the summer to about October. Males may mate with more than one female, or the same female several times over a period of several years. A female may lay fertile eggs for up to four years after one successful mating. Nesting occurs from May through July. Most nests are started at twilight and finished through the night. Nests are usually dug in sandy or loamy soil, using the hind legs. The eggs are laid in this cavity and the nest is carefully covered up again. There are 3-8 eggs laid (usually 4-5) and they are elliptical with thin, white, flexible shells roughly 3 cm long by 2 cm wide. T. carolina triunguis pulsate their throats in front of the female. Males climb on the females' carapace with all four feet and then pulsate. The actual copulation is the same in all subspecies, with the male standing somewhat upright, leaning the concave part of his plastron against the back of the female's carapace. It is in this balanced position during which the male fertilizes the female with his penis. Males sometimes fall backwards after copulation, and if they can't right themselves they die of starvation.

Offspring

Temperature dependent sex determination. Nests that are 22-27 degrees Celsius tend to be males, and those above 28 degrees Celsius tend to be female. Terrapene carolina are well developed at birth (precocial) and grow at a rate of about 1.5 cm per year during the first five years, at which time they reach sexual maturity. Growth slows down considerably after that but has been reported to continue for over 20 years.

Conservation

Status

Three-Toed Box Turtles are not considered endangered at the national level in the United States, Canada or Mexico, although several U.S. states, including Michigan, New Hampshire, Massachusetts and Connecticut, list T. carolina as a species of special concern. It is considered endangered in Maine. IUCN: VulnerableCITES: Appendix II

Historical

Current Threats

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