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Turtle and Tortoise Newsletter, 2000, 5:9-10
© 2000 by Chelonian Research Foundation

Turtle and Tortoise Newsletter

Oh, Those Box Turtles

Don Zeiller
88 Norman Place, Tenafly NJ 07670

This 81 year old man has been observing box turtles since he was three or four years old and thought he had seen everything to be seen about them. He had even written a book about box turtles, “So, You Like Turtles!” One of the things he explained therein was that box turtle shell prints are like fingerprints that, once formed during their juvenile years, remain the same throughout their lives (Fig 1).




Figure 1. Turtle L3(2) at 4, 8, and 13 years. Notice the pattern on the indicated costal scute.

But a few weeks ago for the first time, I noticed that two box turtles in my possession have very similar markings. You will see by the next set of pictures (Fig 2) that the markings are not identical but do contain enough characteristics to suggest that these two turtles must have shared at least one parent. Box turtles are not monogamous; a female in my sanctuary could have mated with any of several dozen males.



Figure 2. Female L-8 above, male L-8 below. Compare the pattern in the circled scute. Both turtles were born in 1988.

Over the years I have observed hundreds, if not thousands of box turtles, but have never seen such similarity. The turtle at the top is a female and the picture at the bottom is a male. In checking my records, they were born about 1988, so as of this date they are about 13 years olds.

Why haven’t I seen more turtles with similar markings? That is, so that I could say to myself, “that turtle must be one of Sally’s (to use a name) family.” There is one very good reason—not many hatchlings survive. The female box turtle lays about seven eggs/year. Is it by design that she lays seven, hoping that one will survive? Think of this, a female box turtle starts laying eggs at about twelve and can lay a clutch of eggs every year through age seventy or more. This is what I believe based upon my records. For example, forty years ago my daughter, Vivian, acquired a box turtle with all the indications of a forty year old turtle. The turtle is now eighty years old and still laying fertile eggs. She is a small individual and perhaps that is why she lays only four eggs per annual clutch, or is it because of her age?

With so much fertility, why are box turtles on the decline? If one female can lay 400-500 eggs in her lifetime, surely there must be turtles all around us. But there aren’t. First of all, the female box turtle lays her eggs whether or not they are fertile. As habitats are destroyed, the number of turtles become fewer and there is less chance of mating. Many animals eat turtle eggs, including raccoons, skunks, and opossums. If the eggs survive, many animals eat the hatchlings and the weaker hatchlings die off over winter. Roads and automobiles decimate both young and old turtles.

I guess that is why we don’t find many box turtles with similar patterns and can thus say, “this one must be from Sally’s family.”