Common box turtle

Terrapene carolina was first described by Carl Linnaeus in his landmark 1758 10th edition of Systema Naturae. It is the type species for the genus Terrapene and has more subspecies than the other three species within that genus. The eastern box turtle subspecies was the one recognized by Linnaeus. The other five subspecies were first classified during the 19th century.[4] In addition, one extinct subspecies, T. c. putnami, is distinguished.[5]

Subspecies

Parentheses around the name of an authority indicate that he originally described the subspecies in a genus other than Terrapene.

The hinges of the box turtle's lower shell

The common box turtle (Terrapene carolina) gets its common name from the structure of its shell which consists of a high domed carapace (upper shell), and large, hinged plastron (lower shell) which allows the turtle to close the shell, sealing its vulnerable head and limbs safely within an impregnable box.[6] The carapace is brown, often adorned with a variable pattern of orange or yellow lines, spots, bars or blotches. The plastron is dark brown and may be uniformly coloured, or show darker blotches or smudges.[7]

The common box turtle has a small to moderately sized head and a distinctive hooked upper jaw.[7] The majority of adult male common box turtles have red irises, while those of the female are yellowish-brown. Males also differ from females by possessing shorter, stockier and more curved claws on their hind feet, and longer and thicker tails.[7]

There are six living subspecies of the common box turtle, each differing slightly in appearance, namely in the colour and patterning of the carapace, and the possession of either three or four toes on each hind foot. The subspecies Terrapene carolina triunguis is particularly distinctive as most males have a bright red head.[7]

The common box turtle inhabits open woodlands, road sides, road middles, marshy meadows, floodplains, scrub forests and brushy grasslands[6][7] in much of the eastern United States, from Maine and Michigan to eastern Texas and south Florida. It was once found in Canada in southern Ontario and is still found in Mexico along the Gulf Coast and in the Yucatán Peninsula.[8][7] The species range is not continuous as the two Mexican subspecies, T. c. mexicana (Mexican box turtle) and T. c. yucatana (Yucatán box turtle), are separated from the US subspecies by a gap in western Texas. Three of the US subspecies; T. c. carolina (eastern box turtle), T. c. major (Gulf Coast box turtle) and T. c. bauri (Florida box turtle); occur roughly in the areas indicated by their names. T. c. triunguis (three-toed box turtle) is found in the central United States.[7] The species has become extirpated from Ontario and Canada as a whole.[9]

Eastern box turtle Terrapene carolina carolina	Florida box turtle T. c. bauri	Gulf Coast box turtle T. c. major
Three-toed box turtle T. c. triunguis	Mexican box turtle T. c. mexicana	Yucatán box turtle T. c. yucatana

Egg-laying

Common box turtles are predominantly terrestrial reptiles that are often seen early in the day, or after rain, when they emerge from the shelter of rotting leaves, logs, or a mammal burrow to forage. These turtles have an incredibly varied diet of animal and plant matter, including earthworms, snails,[10] slugs, insects, wild berries,[6] roots, flowers, fungi, fish, frogs, salamanders, snakes, birds, eggs,[10] and sometimes even animal carrion[7] (in the form of dead ducks, amphibians, assorted small mammals, and even a dead cow).[10]

In the warmer summer months, common box turtles are more likely to be seen near the edges of swamps or marshlands,[6] possibly in an effort to stay cool. If common box turtles do become too hot, (when their body temperature rises to around 32 °C), they smear saliva over their legs and head; as the saliva evaporates it leaves them comfortably cooler. Similarly, the turtle may urinate on its hind limbs to cool the body parts it is unable to cover with saliva.[11]

Courtship in the common box turtle, which usually takes place in spring, begins with a "circling, biting and shoving" phase. These acts are carried out by the male on the female.[7] Following some pushing and shell-biting, the male grips the back of the female's shell with his hind feet to enable him to lean back, slightly beyond the vertical, and mate with the female.[12] Remarkably, female common box turtles can store sperm for up to four years after mating,[7] and thus do not need to mate each year.[12]

In May, June or July, females normally lay a clutch of 1 to 11 eggs into a flask-shaped nest excavated in a patch of sandy or loamy soil. After 70 to 80 days of incubation, the eggs hatch, and the small hatchlings emerge from the nest in late summer. In the northern parts of its range, the common box turtle may enter hibernation in October or November. They burrow into loose soil, sand, vegetable matter, or mud at the bottom of streams and pools, or they may use a mammal burrow, and will remain in their chosen shelter until the cold winter has passed.[7] The common box turtle has been known to attain the greatest lifespan of any vertebrate outside of the tortoises. One specimen lived to be at least 138 years of age.[13]

This article incorporates text from the ARKive fact-file "Common box turtle" under the Creative Commons Attribution-ShareAlike 3.0 Unported License and the GFDL.