Photographed by Bette Jackson



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Hi, I'm Dr. Jerry Jackson, out with the wild things. The sexes of box turtles are usually easy to tell apart. Females tend to be larger, an adaptation for carrying their eggs. And males tend to have the shell of their underside, their plastron, indented, allowing them to easily raise themselves onto the back of the female during mating. These differences increase with age, and aren't so evident in younger box turtles. But there are other ways to tell the boys from the girls.  The inner toes of a male box turtle can be turned inward to allow him to hold on to the female during mating. The female’s inner toes do not turn inward. The eyes of the male box turtle are often, but not always, bright red, whereas the eyes of females are brown. One of the most fascinating things about the sexes of box turtles, and many other turtles, is that the sex of an individual is not determined by a special sex chromosome, as in humans and many other animals. The sex of these turtles is determined by the temperature at which their eggs develop. In general, turtles hatching from warm nests become female, and turtles from cold nests are males.