Sunday, June 17, 2018

A Slow Start for Snapping Turtles

snapping turtle 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% 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%, with two years experiencing losses of 100%. 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. The illustration for this column was drawn by Adelaide Tyrol. The Outside Story is assigned and edited by Northern Woodlands magazine, and sponsored by the Wellborn Ecology Fund of New Hampshire Charitable Foundation.

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The Adirondack Almanack publishes occasional guest essays from Adirondack residents, visitors, and those with a biding interest in the Adirondack Park.

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16 Responses

  1. Amy Godine says:

    This is terrific. Thanks!

  2. Chris says:

    Very interesting and educational. Thanks!

  3. Daniel Nicponski says:

    We were at Boreas Ponds 2 days ago; a pair of turtles were digging holes and laying eggs into them/covering them up. This was right on the road immediately to the east of the bridge portion of the dam. These were each about 20-25 lbs in mass, I would estimate. Lovely to see them, certainly. Hopefully no one will disturb them at all….

    • Boreas says:

      Daniel,

      That is one problem these turtles can’t deal with. They view the side of a road as a beach. Problem is, cars and predators use roads for travel. In season, all a fox, coyote, or ‘coon has to do is take a stroll down any road near water and find turtle eggs – possibly wiping out a dozen nests in an evening. They rarely last more than a day around my area before they are eaten or crushed by cars pulling off the road.

    • Jim S. says:

      Anyone who would disturb the nest would be turtley shellfish

    • Linda W. says:

      That must have been an awesome sight!

  4. Bridget Foster says:

    My property in central NY has a brook, a pond, and a marsh. Larger beaver-made ponds are within spitting distance. So there are plenty of snapping turtles in the area and lots of nests. Most of which are dug up as mentioned, within 24 hours. This June along the road, in my yard, and on the old rail bed bordering my property, I’ve already counted 36 nesting sights, one with a very large turtle actively laying when I walked by. They are very docile when laying and not much seems to bother them. I’ve often wondered why I’m not knee deep in baby snappers every year — but the predation rate mentioned above answered that question. After the predator digs out the eggs, I’ve covered the hole only to find it re-dug again the next day! Snappers are fascinatingly prehistoric and I take photos of every one I see, although honestly — they pretty much all look the same. Thank you for the great article!

  5. Larry Master Larry Master says:

    Nifty observations and terrific article. Thanks for researching and writing this.

  6. Paul says:

    If you live along or near these roads one thing that you can do is carefully put an orange pylon next to where the eggs are laid. They usually stay on waters side of the road. Folks do this along the South River Road near St. Regis Falls. Probably why we have so many turtles around there!

    • Boreas says:

      That would help for humans, but any predator worth its salt would eventually learn to see those pylons as a food flag.

      • Paul says:

        Seems to work pretty well in that one area where I have seen it. Maybe all the predators in that area are busy looking for eggs at all the orange pylons that don’t have eggs?

        • Boreas says:

          They tried the pylons this year at Wickham Marsh and the eggs were dug up all along the road (1/8 mile) despite the pylons. BUT it is close to Port Kent – a “developed” area. ‘Coons, fox and other predators may simply be more numerous or concentrated in this area as certain generalist predators are attracted to human habitation. Or the nests are simply too concentrated to resist.

          • Paul says:

            Boreas, my comment was more of a joke. I would not try and guess what the predators are up to. Just happy to see all the turtles we have in that area. At 94% it sounds like the predators are doing well even w/o our help! Not much “trash” and certainly no agricultural fields in the area so maybe a better natural balance. Saw one recently that was huge. Must have been almost a centagenarian!

  7. Big Burly says:

    Thank you for this important information.

  8. Linda W. says:

    I never realized the odds were stacked so high against the snapping turtle. I have great respect for them to begin with and help them across roads, but this has made me love them even more!

    • Boreas says:

      Linda W.,

      Unfortunately the odds of reaching breeding age are quite steep for any cold-blooded vertebrate. Habitat loss (especially rain forests), climate changes, draining wetlands, water and air quality, roadway mortality, disease, and even UV radiation are just a few other challenges in addition to predators. Humans don’t instinctively have soft spots for reptiles and amphibians, making things worse. The best we can do is give them their requirements for space, habitat, and clean air/water and try not to make matters worse.

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