The Outside Story
by Anna Morris
Until 65 million years ago, huge reptiles dominated our planet — and every summer I think they might be making a comeback. The sight of a snapping turtle hauling herself onto a sunny log or lifting her incredible bulk on mud-colored legs always fills me with prehistoric daydreams. Turtles have roamed the Earth for about 200 million years, meaning they were around during the time of the dinosaurs.
Common snapping turtles (Chelydra serpentina) have a reputation for being, well, snappish. A snapper’s mouth is a sharp-edged, scissor-like beak which it uses to eat fish, snakes, and frogs, and to slice through aquatic plants. Snappers also use these beaks to defend themselves from predators, who might otherwise find a tasty meal by flipping a turtle on its back, exposing its fleshy legs. It’s fair to be intimidated by a snapper’s size, as wild-living males weigh on average 35 pounds; the largest reported common snapper, a captive-living male, weighed 86 pounds. Adult snapping turtles are solidly at the top of the freshwater food chain, but for eggs and young turtles, it’s a different story.
In early June, a female snapping turtle, having mated in April, will emerge from her pond and crawl to a sandy spot to lay her eggs. She may walk several miles in this search, and is vulnerable to being hit by vehicles, as she may cross multiple roads on her way to the best nesting sites, and may even choose a sandy roadside as a nest. If you encounter a snapping turtle in the road, a good way to move it to safety is to use a snow shovel to scoop it up and carry it across in the direction it was traveling.
Once she’s found the spot and scraped out a deep hole with her claws, a female snapping turtle will lay roughly 30 eggs. She then covers the hole and abandons the site; her sole parental investment is to select this environment, trusting that the temperature underground remains within the sweet spot of 70 to 72 degrees to produce about half male and half female young. Because turtles experience temperature-dependent sex determination, if the nest is too warm, the hatchlings will skew female; too cold, and they will be male. If the digging and laying process is successful, the turtle may return to the same general area next year. However, an estimated 90 percent of snapper nests are destroyed by predators such as foxes and raccoons before the eggs hatch.
If the nest remains untouched, the eggs incubate for the rest of the summer. The young nose their way out of their leathery eggshell with an egg tooth, like those found in hatching birds, and dig through the sandy soil with their claws as their mother had months ago. The hatchlings then begin walking downhill, the tried and trusted way for these ancient animals to find a body of water.
With their rough, dark-colored shells and long spiked tails, hatchling snappers resemble adults in every way except size. A freshly-hatch snapping turtle is only about the size of a half dollar. At this stage, young snappers are far, far down the food chain. Their shells are somewhat flexible in their first months of life, and herons, raptors, foxes, mink, and even bullfrogs will snap up baby snappers. Hatchlings are also hit by cars as they try to cross roads.
Young snapping turtles may forgo eating during their first fall, as their primary drive is to find a safe place to spend the upcoming winter. Settling into the mud at the bottom of a pond, they will while the winter away, reducing body temperature and heart rate, not eating, and breathing only through the skin around their mouth and cloaca. They don’t need a lot of air during this time because they are not hunting or eating; the small amount of oxygen that passes across these thin areas of skin is plenty to sustain them through the winter. When the snapper reaches about five inches in length, which can take from four to seven years, depending on the climate, it is ready to start breeding.
I’ve had the pleasure, on a warm March day, of looking down through the clear ice covering a local pond to see a snapping turtle swimming lazily around, although the surface had not yet thawed. There she waited, ready to begin the cycle again.
Anna Morris is an environmental educator at the Vermont Institute of Natural Science. Illustration by Adelaide Murphy Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine and sponsored by the Wellborn Ecology Fund of the New Hampshire Charitable Foundation: www.nhcf.org.