Turtles face long odds, but people can help them survive

by Emily Stone
Cable Natural History Museum

Wood turtles use the sun to help regulate their body temperature. The get their name from the pattern of growth rings on their shell that resembles tree rings. Photo by Wilfried Berns, Creative Commons. Wood turtles use the sun to help regulate their body temperature. The get their name from the pattern of growth rings on their shell that resembles tree rings. Photo by Wilfried Berns, Creative Commons. The shiny brown shell of a snapping turtle created a buzz of excitement among the circle of eager kindergarteners.

I love this part of the lesson. After we talked about turtles and how they prepare for winter, each kid got a chance to wear the shell and pretend they’re a turtle.

To entertain myself even more, I made up new species of turtles based on the kids’ clothes. Here’s a blue-legged turtle! An invisible camouflage turtle!

This one’s a pink-sparkly turtle! And a green-footed turtle! Some giggled, and some were earnestly serious about the responsibility of wearing such a cool shell.

It’s been a week of turtles for me. Not only did I christen four classrooms worth of new turtle species, I also hosted a dinner lecture for adults about turtles. It was MY chance to be on the learning end of the equation.

Bob Hay, former Cold- Blooded Species Monitor for the Wisconsin Bureau of Endangered Resources, spent much of his professional career working on turtle conservation, and recently split away to start his own nonprofit called Turtles for Tomorrow. Based in Madison, he’s been doing quite a bit of work up north to improve the nesting habitat of wood turtles, which are a threatened species in Wisconsin.

Turtles on the whole have the cards stacked against them in today’s world, says Bob. They take many years to mature and begin reproducing, they lay relatively few eggs in a year, and they travel widely in large home ranges (and therefore encounter more dangerous roads and damaged habitats). To compensate for all those challenges, turtles also have an impressively long life span. If they make it to maturity, they can live 40 to 70 years or more!

Wood turtles grow and age beautifully. The individual scutes (scales) of the carapace (top shell) grow annual rings that form concentric circles. This pattern is more pronounced on wood turtles than any other Wisconsin turtle, and its resemblance to a tree’s growth rings contributes to their name. Eventually the many layers of scutes create a strong shell, similar to laminated plywood.

Also appropriately for their name, wood turtles spend quite a bit of time feeding on land and in forests. Fast flowing streams with dark, tannin-stained water are another integral part of their habitat. Dark water is so important that the turtles will be absent from any clear-water tributaries, even though the two types of streams are connected. High-energy currents result in sandy or rocky bottoms, which wood turtles walk along—rather than swimming— using their scaly feet, sharp toenails and un-webbed toes. On the bottom of these streams, wood turtles spend the winter either hiding in the eddy downstream of a big rock, or secured inside the maze of tree roots submerged on an outside bend.

When spring comes, these ectotherms (dependent on external sources of body heat) clamber up the bank to start basking. On their way out of the river, the turtles throw sand onto their backs. When the sand dries, it perfectly matches the parched khaki color of last year’s dried fern fronds and provides excellent camouflage. On hot days, speckled alder thickets provide shade and prevent overheating.

Spring warmth is necessary for egg development within female turtles. Once she’s ready to lay them, a female wood turtle will seek out soft sand with little plant or tree cover. By seeking sites without vegetation, she avoids both the challenge of digging through roots, and cooling shade that would slow her babies’ development. Using her “reptilian brain” the mama turtle is able to dig her nest the exact size needed to fit her 3-21 eggs. If the digging gets too tough, though, such as in compacted gravel along roads, she may spend too much time searching for a good nest spot and delay egg laying until it’s too late for them to develop fully. Or she’ll get hit by a car. Unlike some other native turtles, newly-hatched wood turtles can’t overwinter in their nest. They need to emerge in time to access a water body that stays liquid through the winter.

Many eggs never even get to that point. Nest predation is almost 100%. When coyotes and foxes find a nest they eat the eggs whole—turning their scat bright yellow with white shell fragments. Raccoons smell the fresh subsoil brought up during excavation, and often raid nests the night they are made. Skunks have an excellent sense of smell, and seem to be able to detect nests even weeks later. Badgers have been observed putting their ear to the ground during hatching season and following the scratching of fresh hatchlings to a buffet.

With all this predation (raccoons especially have increased in number over the past couple decades), turtles don’t have much of a chance. That’s where Bob Hay comes in. He and his team are restoring and creating nesting areas with sand and gravel perfect for digging, and with ample sun. Then he strings electric fencing just a few inches off the ground, and lays wire mesh underneath it.

The scheme works. So far, Bob has restored four nesting sites and created 15 “luxury homes for nesting turtles,” as he calls them. In 2015, on just 4 of the sites, 18 nests produced 132 hatchlings. He’s making progress.

Bob’s photos of baby turtles were ridiculously cute. He’s doing amazing work to ensure the future of this particular child of the Northwoods. It’s people like him that give me hope for the future of those blue-legged and pink-sparkly turtles, too!

To find out more about Turtles for Tomorrow, and support their work, visit www.turtlesfortomorrow.org.

Special Note: Emily’s book, Natural Connections: Exploring Northwoods Nature through Science and Your Senses is here! Order your copy at http://cablemuseum.org/ natural-connections-book/.

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