by Whit Gibbons

July 13, 2014

A remarkable coincidence associated with a road-killed turtle and her eggs has made scientists reflect on the value of preserving wildlife that can’t seem to stay out of harm’s way.

Brett DeGregorio at the University of Illinois conducts research on the U.S. Department of Energy’s Savannah River Site in South Carolina. Several years ago, with the help of numerous students and other colleagues, I began doing research on turtles at the same site through the University of Georgia’s Savannah River Ecology Lab. Over the years all of us collectively have captured, marked for identification, and released more than 30,000 freshwater turtles.

One of the most common species in the region is the yellow-bellied slider turtle. When returning from a field site, Brett found a slider that had been hit by a car on a highway. The turtle’s shell was badly cracked but Brett rescued it and took it back to the lab to see if the injury could be repaired. We often use superglue with great success to patch together small cracks in shells of injured turtles.

While the turtle was in the lab she laid eggs and then died. Brett placed the eggs on damp paper towels so they could be incubated in the lab. Turtle eggs can be hatched if they are kept on moist material and at room temperature.

Having an injured turtle lay eggs in the lab is not that unusual, but the rest of the story is noteworthy. As Brett was attempting to repair the shell, he noticed three small notches, tiny scars on the plates that form the edge of the shell.

These were old identification marks from our earlier turtle research. For decades we notched the margins of the shells in combinations so that each individual had a unique code, a sort of turtle Social Security number that would allow it to be identified for its entire life.

When Brett realized that the turtle had one of the old identification codes on its shell, he asked Brian Metts of SREL to check the turtle data files. He wanted to know what he could learn about the dead turtle’s past. Turns out she had hatched from an egg two decades earlier.

How did we know this? Brian was certain of the turtle’s age because this female turtle’s mother had been picked up as a highway casualty at the exact same spot 20 years earlier. The mother had died in the lab but had laid eggs before she did so. Those eggs were incubated and hatched in the lab.

As per our usual procedure, the baby turtles in the clutch 20 years before had been given their own identification codes. They had then been released as week-old hatchlings back at the wetland near the highway where the mother had been found.

Other turtles that had been previously marked have been recaptured as many as 20 years later. But what are the chances of a road casualty resulting in offspring that later suffered the identical fate as the mother? The odds exceed lottery-level probabilities and raise some interesting questions.

By returning a new batch of baby turtles into the wild, are we preserving ones with a genetic predisposition toward crossing roads when it’s time to lay eggs? Are we putting ourselves in the same category as well-meaning people who push stranded whales and dolphins back out to sea?

Big sea mammals that beach themselves do not have a sustainable career as marine leviathans. Should these particular turtles be left by the side of the road if they are injured? In other words, should we help keep animals in the gene pool if they can’t make it on their own in today’s world?

We have decided not to overanalyze the question of whether we are creating an animal welfare dependency program for turtles, though we can’t help speculating. If any road-killed granddaughters of the turtle from 20 years ago end up in the lab we may know the answer.

If you have an environmental question or comment, email

(Back to Ecoviews)


SREL HomeUGA Home SREL Home UGA Home