The Eastern Box Turtle (Terrapene carolina)

The Eastern Box Turtle (Terrapene carolina) is one of two species of box turtles found in the United States. It is the only "land turtle" found in North Carolina and is also the state reptile. Box turtles are extremely long lived, slow to mature, and have relatively few offspring per year. These characteristics, along with a propensity to get hit by cars, make the box turtle a species particularly susceptible to human-induced problems.

Identification and Classification | Sexing Box Turtles | Habitat Preferences | Food Preferences | Box Turtle Life History | Concerns


Identification and Classification

Box Turtles are the most common terrestrial turtle in the eastern United States. They are small to medium sized turtles, attaining a maximum length of about 8 inches and having a highly domed carapace. A key characteristic of box turtles is their hinged plastron (bottom of the shell) that can be shut completely to exclude predators. Although mud, musk, and blandings turtles also posses hinged shells, they cannot be closed completely. Superficially, box turtles resemble tortoises but they are actually more closely related to many aquatic turtles and belong to the same family as spotted, bog, chicken, map, and painted turtles, as well as sliders, cooters, and diamondback terrapins. Box turtles in the United States are divided into two species, the eastern box turtle (Terrapene carolina), which ranges from Texas throughout the southeast and north to Michigan and southern Massachusetts, and the western box turtle (Terrapene ornata), which ranges west of the Mississippi to Colorado and New Mexico. The western box turtle is superficially similar to the eastern box turtle but is typically smaller and has a shell marked with radiating yellow lines. There are an additional two species of box turtle that are endemic to restricted habitats in Mexico. One of these species (Terrapene coahuila) is almost totally aquatic.
Eastern box turtles are highly variable in shell shape, pattern, and coloration. Based on these differences, four subspecies of eastern box turtles have been designated. The most widespread subspecies is simply known as the eastern box turtle (T. carolina carolina). This turtle ranges along the entire east coast of the United States from Massachusetts to northern Florida, as far west as the Mississippi River, and north to the Great Lakes. Although this subspecies is highly variable in coloration, it is often more brightly colored than the other subspecies and almost always has four claws on the hind feet.

 
 

 

 

 

Range of the Eastern Box Turtle

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Range of the Western Box Turtle

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Eastern Box Turtles (Terrapene carolina carolina)

The florida box turtle (T. carolina bauri) is distributed throughout peninsular Florida. This subspecies typically has a highly domed shell marked with radiating yellow lines and three claws on each hind foot. The largest, and least widespread subspecies of eastern box turtle is the gulf coast box turtle (T. carolina major). This subspecies ranges along the coast of the Gulf of Mexico from the Florida panhandle to the Mississippi delta. Its coloration resembles T. carolina carolina but it is larger, reaching a length of over 8.5 inches, and has flared shell edges. It also usually has four hind claws. The final subspecies of the eastern box turtle is the three-toed box turtle (T. carolina triunguis). This subspecies often has an almost pattern less, brown shell with some red around the head, neck and forelegs, and three claws on the hind feet. The three-toed box turtle ranges extensively west of the Mississippi River through the southern Midwest and Texas. Although this range overlaps considerably with the western box turtle, the two species are usually separated by habitat preference. Three-toed box turtles prefer woodlands and damp brush while western box turtles inhabit more arid, open habitats.

Three-Toed Box Turtles (Terrapene carolina triunguis)

 

Sexing Box Turtles

As previously stated, eastern box turtles exhibit high amounts of variation in appearance. Because of this, sexing turtles can often prove difficult, especially to someone unfamiliar with box turtles. Despite these difficulties, though, there are several characteristics that can often be used to correctly determine the sex of a box turtle. Probably the two most reliable features used to sex box turtles are shell shape and tail length. Males generally have longer and wider tails than females as well as more flattened shells.

This picture clearly illustrates the typical shell shape differences between male (left) and female (right) eastern box turtles

 

Female

Two other features useful in sexing box turtles are eye color and plastron (bottom of the shell) concavity. In general male box turtles have very orange or red eyes and a slightly concave plastron while females have brown or light orange eyes and a plastron that is almost completely flat.

Male

Habitat Preferences

Eastern box turtles are amazingly versatile animals and inhabit a wide variety of habitats from wooded swamps to dry, grassy fields. Although these turtles can live in a variety of different habitats, they are most abundant and healthy in moist forested areas with plenty of underbrush. Although not aquatic, box turtles will often venture into shallow water at the edge of ponds or streams or in puddles. Box turtles do not travel far, usually living within an area less than 200m in diameter. In cold climates they hibernate through the winter in loose soil at a depth of up to two feet.

Food Preferences

Box turtles are omnivores in the broadest sense of the word. They will eat almost anything, animal or plant, that they can fit in their mouth. Intriguingly, it is thought that young box turtles are primarily carnivorous and that as they grow their diet shifts more and more towards plant material. Favorite foods include almost any insect (although they seem to particularly relish worms and slugs), virtually any fruit or berry, mushrooms, a variety of vegetable matter, and even carrion. Interestingly, box turtles are even able to eat many mushrooms that are toxic to humans.

Box Turtle Life History

Box Turtles are some of the longest lived and slowest reproducing species in the world. When a box turtle first hatches from its egg it is a mere 1.25 inches long. Little is known about the lives of young box turtles because they are so secretive and hard to find. In fact, it is very rare to find a box turtle much smaller than about 3.5 or 4 inches long. It is thought that these young turtles spend most of their time concealed in brush and leaf litter and feed primarily on insects. Box turtles generally grow slowly, reaching sexual maturity at between 7 and 10 years old and 5 or 6 inches in length. Once mature, a female box turtle will lay between 3 and 6 eggs each spring in a shallow nest. The eggs are left unguarded and hatch in the late summer or early fall when hatching occurs. Box turtles commonly reach 25-30 years of age and there are well-documented cases of them living to 40 or even 50 years. Although questionable, some sources even report box turtles topping 100 years of age.

Conservation Concerns

Although box turtles are still fairly common over much of their range, their future is uncertain. Box turtles are slow growing, have few young, and have exhibited delayed sexual maturity. These qualities make them particularly susceptible to damage due to human activities. First and foremost among problems faced by box turtles is habitat destruction and fragmentation. Fragmentation is defined as the process by which natural or seminatural habitats are seperatated from similar habitats by land that is used by humans (2). As areas of suitable habitat become fewer and farther between, box turtle populations will decline and individual populations will become increasingly vulnerable to extinction. Confined to smaller areas, the turtles will have an increasingly difficult time finding food or mates. These small, isolated populations may suffer from inbreeding and other genetic problems. Box turtles may also wander out of their isolated habitats into the matrix (the land used by humans), where they are particularly susceptible to accidental death due to humans. Each year countless box turtles are hit by cars or trains when they attempt to cross roads or railroads. Others are accidentally killed by lawn mowers, tractors, and farm equipment.

Another concern is the capture of box turtles for the pet trade. The impact of taking turtles from the wild can be devastating to local populations. Over the span of their lifetime, female turtles will lay hundreds of eggs, but only 2-3 of these offspring will survive to adulthood. These offspring will eventually replace their elderly parents, allowing the population to remain at a stable size (1). But, if box turtles are taken from the wild to become pets, or are killed by human activities, they are removed from the overall breeding population, the number of offspring drops, and the overall population declines. Additionally, box turtles have a homing instinct that causes them to try to return to the place of their birth if they are moved. As a result, when box turtles that have been taken as pets are returned to the wild, they will head straight for their natal grounds (1). This journey causes the turtles to encounter many dangers, such as roads, predators, and humans. For these reasons, if you are looking for a pet, you should try to find a captive-bred animal or consider a different pet.

This turtle was lucky enough to survive a run-in with a lawn mower
This male box turtle lost his rear leg, perhaps to a dog or a raccoon.

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