They Hatch, and Then They Run the Wrong Way

Set a terrapin hatchling on the sand at Henson's Cove and it will do the one thing you are not expecting.

It will turn around.

Not toward the marsh, which is forty feet away and full of everything a turtle eats. Inland. Up toward the leaf litter and the scrub, away from the water, at a determined pace, on legs about the length of a staple.

Every piece of footage you have ever seen of baby turtles — the frantic sprint down the beach, the surf, the gulls — is the wrong species and the wrong instinct. These go the other way, and once they're in the leaf litter they stay there for two to four years depending on which researcher you ask, doing something nobody has fully explained.

Which is a good introduction to this animal, because almost nothing about it sits where you'd put it.

The turtle that lives in the seam

The northern diamondback terrapin is the only turtle in North America that lives exclusively in brackish water. Not fresh, not salt. The seam between them, which is a hard place to specialize in, because it moves.

In Massachusetts that means Cape Cod, Buzzards Bay and the lower Taunton River and nowhere else. Wellfleet marks the northern edge of the nesting range — the last place on the continent this happens. The state lists them as threatened. They are not listed federally, which turns out to matter in a way nobody planned.

A grown female runs six to nine inches. A male tops out around six. A hatchling is about an inch of mostly gray with the diamond rings still faint on its back, and it weighs about as much as two quarters.

They don't nest until they're eight or older, and they can live past forty. Which means the female digging in the sand behind Lieutenant Island this summer may have hatched before anyone was watching, and may still be nesting when the people currently watching her have retired.

And the sand decided everything. Terrapins have temperature-dependent sex determination: cooler than about 82 degrees skews male, warmer than 86 skews female. Not the parents. Not chance. The weather in July, in the particular six inches of ground one turtle chose.

Twice a day since June, on foot

Mass Audubon's Wellfleet Bay sanctuary has been marking individual terrapins since the 1980s and actively protecting nests since 2005.

There is no clever technology in this. It's people walking the same ground twice a day from June to October, from the first female hauling out to the last hatchling coming up. In 2024, more than 125 volunteers monitored nine locations across Wellfleet, Eastham and Orleans. More than 200 nests were recorded on sanctuary property. The program released 4,810 hatchlings, and 82 percent of the eggs in protected nests survived.

Nests get covered — a cage-like excluder set six inches down, or a flat wire screen the hatchlings can walk out from under on their own — because foxes, raccoons, coyotes and crows all know exactly what a terrapin nest is and roughly when it's worth revisiting.

But the cages aren't the interesting part. The gardens are.

A turtle garden is a cleared, sun-warmed patch of sand, put deliberately between the marsh and the road so a female hauling out can nest without crossing pavement. Nesting season is June and July. So, on this Cape, is the traffic.

Barbara Brennessel, the Wheaton College biologist who has worked the North Wellfleet sites for years, gave the Provincetown Independent the plainest possible accounting of what one patch of sand is worth.

"And those could have been 50 turtle tracks across Route 6."

The year the clutches got smaller, and everybody cheered

In 2023 the nests at North Wellfleet came in at eight to ten eggs. The usual is twelve to sixteen.

Fewer eggs. And the people who dug them up got excited, which requires explaining.

Brennessel's thinking is that small clutches may be coming from young females — first-timers, laying fewer than they will in another decade. If she's right, the shrinking clutch is a receipt. It would mean turtles that hatched under somebody's wire screen in the early 2000s went up into the leaf litter, spent their years wherever they spend them, and have come back to dig on the same beaches as adults.

Nobody has followed an individual turtle across twenty years to prove that. It's a hypothesis, and it's worth saying so.

But it's the sort of hypothesis you can only earn by counting for two decades — and it arrives with a real number attached: 521 nests protected in 2023, breaking the record of 496 set in 2019.

"There's a new wave of younger nesters coming up," Jessica Ciarcia, the sanctuary's turtle research coordinator, told the Independent that fall, "which is a really great sign for the population."

"OK, buddy, you ready to go explore?"

After eighty or ninety days somebody comes back and digs.

The excluder comes off. Sometimes the heads are already up through the soil, waiting. One nest gives you eleven. They go to the lab to be weighed and measured, and then they come back to the exact ground they came out of.

At Henson's Cove in Orleans, the conservation trust turns that into something the public can stand inside. People spread along a wide front at the marsh edge — spread out deliberately, so that no gull or crow gets one concentrated meal — and set the hatchlings into the grass by hand. Children carry them down. In 2024 the trust protected thirteen nests, a record for that site, and put 160 hatchlings into the marsh across the season.

One volunteer, Norma Ganderson, was overheard talking to hers on the way down.

"OK, buddy, you ready to go explore?"

One or two of every hundred will reach adulthood. Everyone standing there knows it. They go anyway, and they say things like that, because the alternative — treating a hatchling as a statistic with a two percent survival rate — is not available to a person holding one.

Two envelopes, one Tuesday in July

On July 14 of this year, two things happened under the Endangered Species Act, and they point in opposite directions.

The U.S. Fish and Wildlife Service and NOAA's National Marine Fisheries Service jointly published a rule rescinding the definition of "harm" — the 1981 language under which wrecking a listed animal's habitat could count as harming it. That takes effect September 14.

The same day, Fish and Wildlife found that a petition to list the diamondback terrapin presented substantial new information, and opened a twelve-month status review.

Nothing changes for these nests this month. The terrapin isn't federally listed, so the harm rule doesn't reach it. What protects the ground these hatchlings are walking into is the state's threatened listing and Massachusetts wetlands law, and that is not a small thing.

But if the review ends where the petitioners want it to end, the terrapin will arrive under a federal statute that has just narrowed what it means to harm an animal by taking away the place it lives. A listing is a door. Somebody adjusted the frame on the way in.

None of which is legible from the marsh edge at Henson's Cove, where the work is a wire screen, a shovel, and a person walking the same half mile twice a day since June.

The hatchlings are going up into the leaf litter either way. That's the one part of this nobody has to argue about.

Wellfleet Bay Wildlife Sanctuary | 291 Route 6, South Wellfleet · 508-349-2615
Nature Center 9–5 daily, trails dawn to dusk · $8 adults, $5 seniors, $3 kids 2–12, members free
Turtle programs run into the fall; dates follow the nests, not the calendar.

Henson's Cove Conservation Area | 33 White's Lane, Orleans · free, about a mile of trail
The hatchling release is a member event, called on a few days' notice. Orleans Conservation Trust, 508-255-0183.