Terrapene carolina, the Eastern Box Turtle

Eastern Box turtle partially withdrawn into its shell
A slightly annoyed Eastern Box Turtle.

Everyone likes eastern box turtles. Ubiquitous to forest, farms and suburbs throughout the Piedmont, enjoying a good basking spot on a road or trail, refusing to behave like a proper water-loving terrapin, and a habit of boxing up instead of running allows an average human on an average hike opportunity for a close examination. The turtle doesn’t care much for being examined, but it’s so hard to resist picking them up and looking into their little turtle faces. Also it is fun to knock on their shells to see if they are home. As said before, everybody likes box turtles.

Box turtles, genus Terrapene, are North American based land-modified terrapins, . Their ancestors were proper pond turtles of family Emydidae, which still contains Terrapene. They lived in fresh water ponds, with a flatish shell and webbed feet adapted for swimming. The oldest identifiable box turtle fossil dates to around 15 million years ago. Sometime prior to that point, a group of Emydidae moved to land, lost the webbing, and became more generally spherical. And that’s our guy.

They are called box turtles due to a hinge in the plastron. The hinge allows them to lose themselves entirely. Some box turtles have a hinge to cover their tails too.

There are six species of Terrapene, with between ten and fifteen subspecies. They are differentiated by markings, shell shape, and somewhat by habit. Note that biologists being biologists, this can change. You can make a good guess on which particular box turtle you have encountered based on geography. The one you will find in the Piedmont is most likely Terrapene carolina carolina, the Eastern Box Turtle.

About Eastern Box Turtles

head of female box turtle showing brown eye
Female box turtle, © 2001, John H. Tashjian, California Academy of Sciences. (eol.org)
Head of male box turtle showing red eye
Male box turtle. 2004 National Park Service (commons.wikipedia.org)
  • Sexing box turtles is pretty easy. Females have brown eyes, males have red. The plastron on a male turtle also is indented (this works for most turtles). You can’t observe this without flipping the turtle, which they would rather you didn’t do.
  • They are known to live at least 120 years. Maximum longevity is unclear.
  • They can be semi-frozen, surviving -2 C for 44 hours. Seriously. Somebody did this. Somebody needs a new hobby.
  • Box turtles will eat pretty much anything: plants, mushrooms, worms, the occasional toe on a dead guy.
  • They will sit in place for weeks for no obvious reason, apparently. just contemplating life.
  • They are extreme homebodies. Home ranges can be less than an acre and they will attempt to return home if dislodged. So please leave them where found. Even the little ones. They’re fine. If they’re on a road, you can move them off the road in the direction they’re going.
  • Sex determination is controlled by nest temperature, with females requiring warmer nests.
  • Counting scute (carapace scales) will sort of indicate age, and sort of won’t.

Let Them Be

Box turtle populations seem to be going down drastically. The causes seem to be the obvious ones: new development, being hit by cars, being bit by dogs, people collecting for sale. However, a new hiking trail can also decimate turtle numbers. Well meaning hikers pick them up, give them a pet, let dog harass them, maybe take them home, knock on the shell to see if anyone’s home, and generally bother them. It’s not just gas stations and housing developments; it’s general stress. If we could let them be, they’d actually survive well in suburban areas. So enjoy your surprise box turtle from a bit of a distance. Your great grandchildren may encounter the same one on the same trail some day.

Next week, musk and mud turtles, aka, the little football guys on the pond edge.

References

References

Dodd, C. K. Jr., North American Box Turtles. 2001. University of Oklahoma Press.

“Eastern Box Turtle.” Wikipedia, available from http://en.wikipedia.org/wiki/Eastern_box_turtle. Accessed 24, March 2014.

“Terrapene carolina carolina.” Encyclopedia of life, available from http://eol.org/pages/1263662/overview. Accessed 24, March 2014.

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