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[Rebecca Stump] Oh, we've got babies!

[Narrator] The race to study and save Maryland's state reptile.

And, keeping fledglings afloat.

An uncommon solution to the woes of the common tern.

Next.

Outdoors Maryland is produced in cooperation with the Maryland Department of Natural Resources.

♪ ♪ [footsteps] [rev of engine] [splashing] [roar of waterfall] [splashing] [waves rushing] [hooves clopping] [beating of wings] ♪ ♪ [Narrator] When dawn lands at the Naval Air Station Patuxent River, on this steamy July morning, [buzzing] Chris Rowe is already in hiding.

[water lapping] [Chris Rowe] There's one about 10 yards off the beach.

Not too far from my position.

[Narrator] From his vantage point atop a sandy cliff on the shore of the Patuxent River, he zeros in on his target.

A female diamondback terrapin, actually- [Chris] Well, there's two together out there.

Really what you see with the terrapins when they're in water is the head, especially when they're looking at a beach, deciding when they're gonna nest, they seem to keep their heads up out of the water quite a bit.

Then they will pull their heads back down under the water and then we don't really know where they're gonna show up.

[Narrator] When a female decides she's ready to nest, she makes a beeline from the water to the shore.

Terrapins seem to love this spot in particular.

A remote beach surrounded by marsh and forests.

That also happens to be home to one of the Navy's helicopter landing zones.

So each summer, nesting season, helicopters land elsewhere, all to accommodate Maryland's state reptile.

That's when Chris, an Assistant Professor at the University of Maryland's Chesapeake Biological Laboratory just across the river in Solomon's Island, returns to study these terrapins.

[Chris] We are examining how diamondback terrapins are responding to the changing climate.

We're looking forward and trying to project how they'll respond to climate change in the future, but we're also trying to get a handle on what's happening with the populations now because climate change is, is happening as we speak.

[Narrator] One question Chris wants to answer.

How will sea level rise impact the terrapins' habitat?

It's an important one because terrapins, unlike other turtles, are uniquely adapted to life in brackish or slightly salty environments, like the marshes in and around the Chesapeake Bay.

[Chris] We don't see terrapins in the sea, in the open ocean.

We don't see them in the fresh waters.

They're restricted to this brackish environment because they've specialized for it.

[Narrator] In Maryland, half of the terrapins current nesting ground is expected to be underwater in the next 30 years.

By the end of the century, more than three quarters will be claimed by the tides.

But it's not just sea level rise that threatens the terrapins reproduction.

Like many other turtles, a terrapin's sex is determined by the temperature of the nest during the incubation period.

In simple terms, the hotter it gets, the more females will hatch.

[Chris] One of the things that we're concerned about is as it gets warmer, we're gonna see an excess of females and a much lower abundance of males.

[Narrator] Chris wants to know more about the factors that influence the sex of the embryo, and for that, he needs to link the mothers to their nests, which is why he waits and waits to catch nesting females in the act.

There's nothing more frustrating than a close call.

[waves softly crashing] While Chris waits, Rebecca Stump, a Natural Resource Specialist with the Navy combs the beach, searching the sand for signs.

[Rebecca Stump] I'm looking for terrapin tracks.

Consistently, they come up out of the water, they're gonna crawl up, find a spot, lay and turn around.

So we're looking for entry tracks and we're looking for return tracks.

[Narrator] Nothing yet, but she's already found one nest today.

[Rebecca] So this particular nest was laid earlier today and I just threw a predator exclusion device, a PED over it.

But we're gonna go ahead and move it a little bit further up so that if we have any major storms, it's not completely inundated.

So I'm gonna go ahead and pull back the sand gently until I see the first egg.

Hopefully they're still pink, which indicates a fresh egg.

After several hours, they start to turn white and we call that chalking.

[Narrator] At that point, simply turning the egg the wrong way could kill it.

[Rebecca] I've come to the top of the first egg and they are still kind of pink, so they're good.

[Narrator] Rebecca runs the air station's diamondback terrapin nest monitoring program.

The goal is to find and protect as many nests as possible.

This is the 66th nest this year.

[Rebecca] I have a couple of tools that I use.

[Narrator] Rebecca carefully weighs and measures each egg.

[Rebecca] I have a pair of calibers that go down to millimeters.

Actually, it goes down to tenths of millimeters.

[Narrator] Recording data that will be shared with Chris and other researchers.

[Rebecca] That's a ginormous egg, way outside the average size.

Well, these all are.

[Narrator] Female terrapins rarely come ashore except to nest once, maybe twice each summer.

The turtles here seem to wait until right around Independence Day to lay their eggs.

It's a busy time for Rebecca and her team.

[Rebecca] All right, for the last step, after we've weighed and measured all the eggs, I'm gonna go ahead and cover up the nest.

[Narrator] And now perhaps the most important part, a black milk crate fashioned with a protective mesh is what Rebecca and her colleagues call a predator exclusion device or a PED.

[Rebecca] All right.

The nest is pretty secure.

If I can't wiggle it, then a predator's highly unlikely to get in here.

[Narrator] The only clue a mother leaves behind after she covers her nest is her scent, which lingers for a day.

Beckoning the coyote's, foxes and skunks.

Those predators that get lucky leave little behind, beyond an empty hole and a few eggshells.

[Rebecca] This program started in 2013 and that first year we didn't really make a big effort to protect the nests.

We had like a 90% predation level when- without protecting them.

[Narrator] These days, predators rarely get a nest.

[soft splash] [Narrator] Back at Chris's end of the beach, it's been a disappointing morning.

[Chris] Today we didn't do very well.

In other words, we didn't get anything.

But that's how it goes, and that's why we spent so much time out here, it is- it's a waiting game.

♪♪ [Narrator] Although Chris didn't catch any females today, he did find a nest that he'll take back to the lab to incubate and hatch.

[Chris] These eggs were collected either from freshly laid nests in the field, or they were collected from females who we caught who were carrying their eggs and hadn't nested yet.

And we brought them into the lab and had them lay their eggs for us in here.

Each one of these containers is a different nest or clutch.

[Narrator] They'll be incubated at different temperatures, all part of an effort to establish a baseline understanding of how temperature affects the sex of the hatchlings.

[Chris] The long term goal is to be able to project roughly what the sex ratios in the future might be.

♪ ♪ [Narrator] Nearly two months later, the eggs in Chris's lab, begin... to emerge.

[Chris] This is a hatchling diamondback terrapin.

This animal hatched about three days ago, still very tiny as you can see, and the shell's still a little bit flexible.

If I turn it over, you see on the belly, this is called the plastron and in the middle of the plastron you see that yellow mark.

That's where the yolk sac was when it hatched.

So when this animal actually came out of the egg, it still had some yolk in a little bubble there on its belly, and over the next day, it fed off of that yolk and now it's all gone.

[Narrator] Chris puts a notch on each shell, [buzzing] and tattoos a unique number on the plastron.

[Chris] Check.

[Narrator] That will help him identify them in case they ever cross paths again.

[water lapping] ♪ ♪ [Chris] We've got these animals back at their nesting site.

We're gonna take them about a half a mile up the beach to where the nest is actually located, and then we'll give them a first taste of freedom.

[Narrator] And if the web of tiny tracks crisscrossing the sand is any indication, Chris's terrapins will be in good company.

[Chris] There are a couple sets of tracks right there.

This is a nest that has eluded both Rebecca's group and my group, and it's, it's fortunate that... that it, it also eluded the predators.

[Narrator] Speaking of Rebecca, she too is on the beach early this morning, when the eggs start to hatch, she and her volunteers check the nests twice a day.

[Rebecca] Oh.

We've got babies!

I count 11 on the surface.

Oh, this is good.

So I'm gonna pull this up real quick.

I'm gonna shake it.

Oh, see I got some hanger-oners.

Yep, there's another one right here.

He's stuck up in here.

Okay, make sure there's no more in here and then I'm gonna scoop them up.

Oh, this one's already going under.

1, 2, 3, 4, 5, 6, 7, 8, 9.... [Narrator] Rebecca's records show 15 eggs were in this nest, but there are only 11 hatchlings.

Before she goes further, she needs to account for them all.

[Rebecca] And what I found was a whole bunch of ants and I dug further and first thing I found was a pink egg.

So this egg never started development.

We have a almost fully developed baby turtle that for some reason ants, got into it.

[Narrator] It's tough to be a terrapin, even with Rebecca's help.

The next step is to weigh and measure each youngster.

[Rebecca] Be still.

[Narrator] The difference between babies in a nest can be pretty drastic.

That's because a single nest can have genetic material from multiple fathers.

Once the data is collected, it's time to let the babies go.

[Rebecca] All right, we're gonna release these guys right at the edge of this grassy area leading to a marsh so they can kind of choose where they wanna go.

[Narrator] For years it was thought terrapin hatchlings, like sea turtles, head straight for the water.

But now, scientists believe most of them spend their first year on land, living in the forest or the marsh grass.

They take a moment to get their bearings and before long they're gone.

The time has come for Chris, too, to say goodbye to his hatchlings.

[Chris] So this is the part where we wish them the best and introduce them to mother nature.

I hope she treats you well little ones.

[Narrator] And with that, they're off.

Taking their first steps into a world that some will not survive, but some will.

And when they return to nest, the cycle will begin once again.

Sunrise on Maryland's eastern shore.

♪ ♪ [birds squawking] Around Ocean City, summer visitors, of all types, often bask in the glow of a new day before launching into action.

[boat engine hums] Like Wildlife Ecologist, Dave Brinker, and Bird Researcher, Archer Larned, who set course for an unusual destination this morning.

A remote raft anchored in the inner waterways near Assateague Island.

A test platform designed to help endangered colonial waterbirds establish nesting sites in this fast changing environment.

[birds squawking] [Dave Brinker] We're trying to come up with ways of sustaining them while we deal with replacing or restoring the missing habitat.

[Narrator] In the past, these common terns would nest on small sandy islands throughout the area, but because those shorelines are increasingly rare these days, so are these migratory waterbirds.

[Dave] Back in the late 1980's, there were a thousand pairs of common terns breeding in Worcester County.

Now the only common terns we have are on this raft, are on one small colony at the Maryland Delaware State Line.

[birds squawking] [Narrator] The first task of the day, taking stock of who's moved in.

Guided by an overhead map of the raft, pinpointing design landmarks like small shade shelters, artificial grass and bird decoys, Archer performs a sort of door to door census.

[Archer Larned] I am looking to see where all of the nests are and how many eggs or what the contents are.

The eggs are very well camouflaged.

They blend into the shells.

So I step very cautiously, carefully, make sure that I look where I'm stepping so I don't step on any eggs.

[Narrator] Still, Archer counts quickly, eager to ease the stress on the birds and herself.

[Archer] Adults are very defensive of their nests and so they will dive bomb me and dive bomb anyone who's nearby and try to get you away from their nest, which is what they would do if any predator came.

Now just hearing that sound makes me duck.

[laughs] I've been conditioned.

16 new nests.

[Dave] That gets us to 78?

[Archer] We had 60.

We had 62 before.

[Dave] So that's 78.

[Narrator] In its second year of operation, the raft has already enjoyed a nearly fourfold increase in occupancy.

A year to year growth rate any Ocean City hotel would crave, especially in mid-June before the true summer rush.

But while the tourists have the beach and boardwalk, increasingly these birds have nowhere else to go.

It's not just the common tern, black skimmers and royal terns are losing nesting habitat too.

Three avian icons now officially endangered in the state of Maryland.

Drastically changing the nature of the area for all who visit.

Like David Curson, Director of Bird Conservation in Maryland for the Mid-Atlantic chapter of the Audubon Society.

[David Curson] These species are a vital part of the ecosystem here in the coastal bays.

And if we didn't have them, that system would be a lot poorer.

[Narrator] Seeking solutions, the Audubon Society partnered with the Maryland Coastal Bays Program and Dave Brinker with the Maryland Department of Natural Resources, the lead funder in this project, to develop and deploy the tern raft experiment.

[pounding] While not an entirely new idea, artificial nesting rafts are rarely this large, 18 individual units totaling 2300 square feet.

All covered by crushed clam shell.

[David] Crushed clam shell basically imitates a natural nesting substrate and provides a place for these terns to build their nests.

[Narrator] The team considered many factors when first towing the raft units into place before the birds arrival in early spring, including water depth, distance from people and potential predators.

They also added little finishing touches like real estate brokers staging a house for sale.

Sights and sounds to entice any passing common tern.

[Dave] When birds fly over, they hear common terns and they go over to inspect the raft and then they see all these decoys and that gets 'em down inspecting the raft.

[Narrator] Biologists call it social attraction, advertising that works.

After wintering in South America, common terns return to this area to mate in late spring, early summer.

Like any good innkeepers, Dave Brinker and his team want to know if the raft has any return visitors.

[Kim] 78!

[Narrator] So when Research Assistant and Project Photographer, Kim Abplanalp, arrives on a pontoon boat with the rest of the team, everyone gets ready for the next phase of work.

[Kim Abplanalp] So we'll leave the two here.

[Narrator] Once the birds settle down again.

[Dave] We're getting ready to band adults at the nest so that we can document birds coming back to use the- the raft year after year.

[Kim] When I hear that sound, it makes me real excited that we've been able to be this successful on this raft so far this year.

[Narrator] On the first approach, Kim and Archer replace eggs with dummy eggs, setting traps over each nest.

When the team backs off, they watch as the broody birds return to tend to their duties, unaware they've been tricked.

The real eggs safely sheltered and incubating on the nearby boat.

[Dave] Oftentimes you don't even see 'em startle when the door drops.

They might start a little bit, but no they're there to incubate and they just sit there until we come and get 'em out of the trap.

[Narrator] The pontoon boat acts as a floating doctor's office, where Dave takes a number of measurements, beak and wingspan.

The bird's parting gift, leg jewelry, uniquely numbered for identification.

Bird bands, not dog tags.

[Dave] We band one adult from every nest.

We did that last year and we marked 19 adults and a remarkable 15 of them came back to nest on the raft.

[Narrator] After the birds are released, the eggs are returned.

Unusually calm, the water looks like glass today, but the raft had to be designed to withstand a much rougher ride.

[Dave] Basically, we take dock segments and use a hinge to put 'em together.

Because it's hinged and it moves with the wave energies, it absorbs a lot of the worst wave energies.

[David] And this means that it flexes, especially in storm events and it's more resistant to the rather rough conditions that you can get in the coastal bays sometimes.

[Narrator] This turbulent environment once moved mountains of sand and sentiment through the local waterways, destroying small sandy islands, but also naturally rebuilding them elsewhere.

But in 1933, the Chesapeake Potomac hurricane cut through the barrier island here, creating the Ocean City Inlet, a landscape feature set in stone a year later with construction of the jetty.

Easy access to the ocean benefited local business, fishing and tourism, but stabilizing the environment also had other consequences.

[David] The whole system's less dynamic.

So now the erosion of these islands is pretty much a one way street towards the loss of these nesting sites.

And they're no longer replaced naturally by sediment or sand.

[Narrator] Add to that climate change and rising sea levels, low lying nesting grounds are quickly disappearing.

[David] Sea level rise is eroding these islands and the islands are not being replaced.

[Narrator] Located just north of the Ocean City Inlet, Skimmer Island paints the picture.

It formed naturally growing to seven acres in size by the 1990's.

But erosion took hold, washing away the shoreline.

The arm corps of engineers tried to reinforce the site using sandy dredge material, but today, what was once critical nesting habitat is little more than a rest stop.

High tide leaves Skimmer Island underwater.

[David] There's nowhere that a a tern or a skimmer could place a nest and have it free of flooding.

[Narrator] On the raft, however, nests and eggs stay dry.

[squawking] But it's only a costly rental.

[David] We should emphasize these artificial islands are just a stop gap measure.

It's not a long term solution.

The- the real long term solution is to restore and maintain the natural sand islands of the coastal bays.

[Dave] If you do it well, it might actually be a little bit cheaper because the islands may last longer than what we do here with the rafts.

[Narrator] For now though, Dave and David must measure success in the short term.

By midsummer, chicks scurry all about the raft.

[squawking] Learning as they go, the team added a small platform just feet away from the main raft, a little life raft for fledgling chicks.

It gets a lot of use.

[David] When they first leave the raft, they're not very good at flying yet, and this gives them somewhere where they can rest.

[squawking] [Dave] It's real rewarding when you see all these flying chicks fluttering around a raft.

But monitoring when you have chicks running around is controlled chaos.

[squawking] [Narrator] Careful with every step, Kim and Archer don't need traps to collect chicks.

[Archer] It gives me hope when I see chicks on the raft.

[Narrator] About 450 birds took up residence on the raft this year, including 150 or so chicks.

[Dave] That's a success cause without the raft, we would've been fledging probably 10 or 15 in the one natural colony.

Next band is 70, chick's three days old.

[Narrator] The chicks also get their rafts souvenirs, ID bands.

But everyone knows these little birds won't return until they're ready to breed.

Three years from now, a homecoming, the team is determined to keep in Maryland.

[Dave] Until we have both a successful island and a successful raft, we're gonna have to keep doing this raft year after year.

[squawking] ♪ ♪ [Narrator] To stream episodes of Outdoors Maryland, visit mpt.org.

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[owl hoots] Learn more about Maryland's diverse natural resources at or download the official mobile app.