Snapping Turtle | Nantucket, MA
Island Science

Ode to an Unloved or Overloved Species

by Dr. Sarah Treanor Bois
Director of Research & Education at the Linda Loring Nature Foundation

I went out to Long Pond by First Bridge recently and came upon a family visiting the pond for the first time. A young girl of the family, maybe 6 years old, suddenly gasped with delight, “Is that a crocodile?!”

In actuality, it was a medium-sized (dinner plate) snapping turtle, slowly surfacing in hopes of a chicken dinner.

Snapping turtles (Chelydra serpentina) have incited wonder for generations. In fact, they have been around for more than 90 million years, virtually unchanged from before the time of the dinosaurs. Snapping turtles have witnessed the drift of continents, the birth of islands, the drowning of coastlines, the rise and fall of mountain ranges, the spread of prairies and deserts, the comings and goings of glaciers.

We can all admire the staying power of the snapping turtle. When you haven’t evolved in 90 million years, that’s like nature saying you are pretty much perfect.

Snapping turtles often seem ornery or aggressive to passersby, but it’s really their only defense. Other turtle species, like painted turtles can fully retract into their shells, so they feel protected by having their fleshy parts hidden. Snappers, on the other hand, have only a thin plastron (the under part of the shell). This allows them freedom for strong swimming, but also exposes a lot of vulnerable turtle flesh. Their main defense is to “snap” at any potential threat. Put yourself in a snapping turtle’s shell for a moment:you might take a nip or two of a creature tried to pick you up!

The snapping turtle’s upper shell, or carapace, is crenellated, the margins spiky; three rows of sharp little points run down its middle. The carapace measures 8-12 inches on an average adult, and the turtles can weigh between 10-35 pounds. Long Pond often boasts larger turtles than that, with some as long as 30 inches. Snapping turtles generally reach maturity at 8 to 10 years and can live up to 40 years or more.

The carapace can vary in color, from green to brown to black; sometimes it is covered with moss. Snapping turtles have a long tail, often as long or longer than the carapace, that is covered with bony plates. They also have a large head, long neck, and a sharp, hooked upper jaw. This hard beak has a rough cutting edge that is used for tearing food—a built-in steak knife!

Basically any fresh and even brackish water body will have snapping turtles in it on Nantucket. They seek out mud-bottomed, weed-choked wetlands, and are opportunistic feeders, dining on whatever is available: carrion, aquatic invertebrates, fish, amphibians, other turtles, small mammals, snakes, the occasional bird (ducklings usually), and all manner of aquatic plants, which may make up more than half their diet.

Snapping turtles rarely leave the water except during the breeding season, when females can travel great distances in search of a place to dig a nest and lay eggs. Nantucket is a snapping turtle’s dream with plenty of sandy roads, banks, and hummocks to build a nest in.

One clutch of eggs is laid in late May to June. With powerful hind legs, the female digs a shallow bowl-shaped nest in a well-drained, sunny location. Over a period of several hours, she lays approximately 20 to 40 creamy white eggs the size of ping-pong balls. After covering her eggs, the female returns to the water, leaving the eggs and hatchlings to fend for themselves. Off-island, turtle nests are often preyed upon by raccoons, skunks, and other mammals absent from our island fauna. Maybe that is one of the reasons for their success on Nantucket.

Generally, hatchlings emerge from their leathery egg in late August through October by using a small egg tooth to break open the shell. When the young hatch, they dig out of the nest and instinctively head to water. Hatchlings are about an inch long with soft shells, and they must make it to water without being preyed upon by dogs, birds, snakes, or feral cats. When they reach water, the young turtles may be taken by fish and other snapping turtles. Once the turtles have grown some and their shells harden, they are virtually predator-free (aside from people and cars).

When I was in graduate school, a friend of mine, Tobias Landberg (now at Arcadia University), was working with the National Geographic “Crittercam” program. He was part of a team that would mount turtles with a special camera to track their movements and get an idea of animal behavior deep down in the muck. This was part of an effort to learn about their natural history, but also to educate the public about our common, native wildlife.

Up until recently, turtle species were only regulated when they were endangered. However, for common species like the snapping turtle, when so little is known about its basic ecology, we won’t know if the population is in trouble until it’s too late. It’s especially important to protect the animals when so little is known.

In some parts of the country, people hunt and trap large snappers for their meat. In the Midwest and Southern US, there’s even a large commercial market. As the diversity of the island grows, so does the harvest of snapping turtles. Until recently, there were no limits or protections of turtle harvests. Today, a fishing license is required to harvest snapping turtles and the legal limit is two per day during the season. The season is virtually year-round except during the breeding months of May through mid-July.

Keep in mind, though, that research has shown that only about one-third of turtles in the US are safe for human consumption. Snappers can tolerate a wide-range of water quality. As such, they can concentrate environmental contaminates and toxic chemicals such as PCBs in their flesh and could pose a health concern if consumed in large quantities. That’s great for the survival of snapping turtles, but maybe not so great for human consumption.

Besides hunting turtles for meat, there is, of course, the ever-popular Nantucket tradition of teasing turtles.

I have never really understood why people on Nantucket love to taunt turtles with chicken legs. First of all it’s completely unsanitary. Secondly it’s taming a wild animal, training them to respond to people. Third, it is illegal.

Yes: jigging for snapping turtles without a permit or license is illegal. Massachusetts now regulates the harvest of snapping turtles. A fishing license is required to fish, and jigging for a turtle is technically fishing even if you don’t plan to eat it.

When I was at the popular turtle dock at Long Pond last week, no one had any chicken. And yet, we counted at least 40 snapping turtles swarming to the dock as soon as they sensed someone (my hunch is via the vibration in the water when we stepped on the dock).

So, why is it so bad to feed the turtles?

• First up, snapping turtles are usually nocturnal. Habituating them to daytime feeding wreaks havoc with their normal sleep patterns.

• Snapping turtles are very territorial. Feeding keeps them in larger numbers in a small area than is otherwise natural. This can lead to disease transmission and other issues seen with wildlife crowding.

• Snapping turtles habituated to people will pursue people for food. This can lead to turtles seeming more aggressive to people who aren’t feeding them. It can also lead to more turtle deaths as they look for food crossing the road.

• When the summer ends, and so does the daily feeding, the turtles will have to adjust to their natural rhythms and feeding behavior. This can cause a decline in the population as turtles fight for the remaining resources.

Please help keep our snapping turtles wild and healthy. Enjoy them from afar with your eyes. The species may yet survive another 90 million years!

Articles by Date from 2012