The Outside Story: A slow start for snapping turtles

One moonless May evening, my husband and I walked down to our local pond, flashlights in hand, to look for toads. We were delighted to discover hundreds of them, floating, darting, and jockeying for position in an explosion of courtship. Their surround-sound trills left our ears ringing.
The toads were frenzied, focused only on each other, and highly concentrated in one small, shallow section of the pond, which prompted my husband to wonder if they weren’t awfully vulnerable to predators that way.
I’d barely had time to contemplate his question when I spied a snapping turtle lurking beneath a cloud of toads. Then, a quiet clap and — just like that — a toad had disappeared into the turtle’s gaping maw. For fifteen minutes, I watched, mesmerized, as the stealthy snapper noiselessly gulped down four more unsuspecting toads. It barely made a ripple.
I consider myself a Toad Person, but I’m a Turtle Person too, and I felt like I’d been given a secret glimpse into The World of Things That Happen When Humans Aren’t Around.
Over the next few days, I excitedly recounted my turtle tale to anyone who would listen, but not everyone found it so enchanting. To some, my experience only served to underscore the snapping turtle’s reputation as a ruthless killer, slayer of brook trout and baby ducks.
Given their primeval appearance, impressive armor, and signature bite, we tend to think of snapping turtles as predators, not prey. As adults, snapping turtles can weigh upwards of 50 pounds and grow to more than three feet in length, with saw-toothed tails, thick carapaces, and powerful jaws, so it’s true that mature snappers have few natural predators aside from humans.
The first year of their lives, however, is an entirely different story.
Each year, from mid-May through early July, female snapping turtles lumber out of the mire in search of sandy soil in which to lay their eggs. They don’t travel far — nests are typically located within 80 feet of the water’s edge — but they often select nest sites along sandy road shoulders, making road mortality a clear danger to adult females and hatchlings alike. Less obvious, perhaps, is the threat posed by predators who thrive in the presence of human development.
Raccoon. Fox. Coyote. Crow. All have benefitted greatly from access to trash, agricultural fields, and other food sources provided, intentionally or not, by us. Where these “mesopredators” thrive, turtle hatchlings struggle to survive.
In northern New York, raccoons destroyed 94 percent of all snapping turtle nests identified in one turtle nesting study. During a six-year study on the reproductive and nesting ecology of snapping turtles in southeastern Michigan, predation rates averaged 70 percent, with two years experiencing losses of 100 percent.
The majority of nests were devoured by raccoons within 24 hours of egg deposition; foxes made short work of the remaining nests later in the season, when the eggs were close to hatching. Recent research in Ontario’s Algonquin National Park found that nest predation by canids, especially red fox, peaked just two weeks before turtle hatchlings were expected to emerge. Ravens, crows, and wild turkeys were also documented feasting on snapping turtle eggs.
How do predators find their way to turtle nests, months after the eggs have been tucked away underground? In Ontario, raccoons and coyotes have been observed following the tracks of early-emerging hatchlings back to their nests and consuming what eggs and young remain in the nest cavity. Canines may also smell their way to nests, guided by the scent of embryonic fluid or the errant rotting egg.
Another intriguing possibility: although freshwater turtles have long been seen as the silent movie stars of the reptile world, Brazilian researchers recently documented giant South American turtle hatchlings vocalizing from inside their eggs, and also after hatching but while still in the nest. The fact that these turtles were thought to be silent until relatively recently may be due to the low volume, pitch, and amplitude of their vocalizations. (In other words, humans can’t easily hear them without specialized equipment.) Could our snapping turtles be calling from inside their nests too — only to be answered by the hungry fox?
Whether they’re led to turtle nests by their eyes, ears, or noses, it’s clear that predators affect the recruitment of young turtles into the population. According to one study, the probability of a snapping turtle embryo surviving to sexual maturity, which typically happens at 15-20 years of age, is less than one tenth of a percent. Such slow recruitment makes these seemingly invincible creatures particularly vulnerable to habitat loss, road mortality, illegal harvesting, pollution, and other human-induced peril.
So, the next time you see a sizeable snapping turtle plodding across the road or lying in wait beneath your canoe — craggy, stinky, and short-tempered though she may be — consider, for a moment, what it took for her to make it to that particular moment in time. Appreciate that she overcame incredible odds. Admire her tenacity, her resilience. And forgive her, perhaps, for the baby ducks.
Brett Amy Thelen is Science Director at the Harris Center for Conservation Education in Hancock, New Hampshire (harriscenter.org). The illustration for this column was drawn by Adelaide Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine, northernwoodlands.org, and sponsored by the Wellborn Ecology Fund of New Hampshire Charitable Foundation: [email protected].

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