By TODD McLEISH/ecoRI News contributor
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| Diamondback terrapins are the only turtle in the Ocean State adapted for life in salt marshes, coves and other quiet brackish waters. (Rhode Island Natural History Survey) |
One of Rhode Island’s rarest turtle, the diamondback terrapin, has
been discovered in new locations in recent years, and those monitoring the
animals say the species is holding its own in the state and may even be
increasing in number.
The only turtle in the state adapted for life in salt marshes,
coves and other quiet brackish waters, diamondback terrapins have been closely
watched for at least 27 years at their major stronghold in Barrington’s Hundred
Acre Cove.
That’s how long Charlotte Sornborger has been monitoring their
nesting success there.
Every year in late May and June, she and a team of volunteers
watch as the female terrapins emerge from the water to lay their eggs in farm
fields and other sites with sandy soils adjacent to the cove.
She estimates
that about 550 terrapins breed in the area.
It takes about 65 to 70 days for terrapin eggs to hatch, with the
last ones this year emerging from their nests on Labor Day weekend.
Coyotes, skunks and raccoons used to scavenge the eggs in many of
the nests, destroying between 200 and 300 nests annually. But that was before
Sornborger began protecting the nests with wire mesh “excluders,” which
prohibit mammalian scavengers from digging down to reach the eggs 6 inches
below the surface.
Sornborger said “a decent population” of diamondback terrapins is
also found in the mouth of the nearby Palmer River, but she has been unable to
learn exactly where they nest, so no one knows how many are there.
Small numbers of terrapins have recently been discovered in the
vicinity of Smith’s Cove, Jacob’s Point and Colt State Park, all in the Bristol
and Warren area.
“We don’t know where they nest at any of those locations either,”
she said. “It’s possible the Hundred Acre Cove population is on the move, so
they may have come from there.”
But, Sornborger said, the terrapins may have always been at those
locations and no one has ever noticed them before.
That’s likely the case in Westerly, too, where a few terrapins
have been found at Napatree Point in recent years.
“We found a dead terrapin at the end of June, but nothing since,”
said Janice Sassi, director of the Watch Hill Conservancy. “There were
indications the past two years that they are nesting.”
A determined effort by the Rhode Island Natural History Survey in
2013 also found about 15 terrapins in some of the coastal salt ponds in South
County.
The biggest surprise, however, was the recent discovery of a
significant population of diamondback terrapins nesting at a private beach at
Rocky Hill School, at the mouth of the Hunt River in Warwick.
Laura Meyerson, associate professor of natural resources science
at the University of Rhode Island, was shown a video of a terrapin hatchling on
the beach two years ago and learned that a teacher at the school has known
about the population for several years.
“We think they’ve been there for a while,” she said. “It’s a
quiet, protected beach on the Rocky Hill property, so there aren’t a lot of
people there to notice them or disturb them.”
Meyerson received a grant from the National Science Foundation to
monitor the Rocky Hill terrapins with Rochelle Devault, a science teacher at
the school. Along with students from URI and Rocky Hill, they were pleased to
observe 87 nests this summer, but unfortunately all but three were eaten by
foxes, raccoons, skunks and domestic dogs.
“It’s not a good situation,” Meyerson said. “We didn’t observe any
hatchlings at all, though the terrapins hide their nests well — they’re masters
of camouflage — so it’s possible we missed some.”
Devault said there may be many more terrapins than the 87 they
observed.
“Our population is extremely shy,” she said. “The number of live
terrapins I’ve seen in the water is pretty high, but the number that come on
land to nest is far reduced from those I see in the water. They look up at me
and turn around and head back in the water.”
As a result, the terrapin monitors at Rocky Hill now hide behind
nearby vegetation as they keep track of the nesting turtles.
Meyerson and Devault plan to explore other marshes near Rocky Hill
next year to look for additional terrapin nesting locations. They also will
install signage to direct dog walkers away from the nesting area. They hope to
learn from Sornborger how to better use excluders to protect the nests.
“We definitely have to figure out how to do a better job at
limiting predation,” Meyerson said. “We really want to build some momentum at
the school to protect the terrapins.”
Rhode Island
resident and author Todd McLeish runs a wildlife blog.
