- Hi, I'm Frank Graff.

How an iconic North Carolina landmark is changing, why sharks are moving into shipwrecks off the coast, and we'll meet a rare woodpecker that loves only one type of forest.

It's the science of the outside on "Sci NC".

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[upbeat music] [upbeat music continues] - Hi again, and welcome to "Sci NC".

Grandfather Mountain is an iconic North Carolina landmark, but because of our changing climate, the ecosystem of Grandfather Mountain in the future will be different from what it is now.

Essentially, as the climate warms, ecosystems needing cooler temperatures move higher up the mountain.

Producer Michelle Lotker explains.

- The highest elevations in our Southern Appalachian Mountains are very unique.

They support some species of plants and animals that occur nowhere else on Earth, only in North Carolina at high elevations.

There's a very long winter, a very short growing season, and there is a huge amount of rainfall and precipitation in these areas.

- Most of the environments here have thin soils, they're very acidic.

Here at Grandfather Mountain, we're known for our winds.

We're one of the windiest places in the state.

[gentle music] - [Michelle] The extreme environments of North Carolina's high elevation peaks play host to an ancient and rare ecosystem, the spruce-fir forest.

- [Misty] We are sitting in a spruce-fir forest near the top of Grandfather Mountain.

This ecosystem is so important for providing habitat for several species of plants and animals that really are unique to this area.

Red spruce, Fraser fir, galax, a variety of mosses and lichens.

Heller's blazing star and Roan Mountain bluet.

These species are adapted to survive in these harsh conditions.

They grow very slowly.

They don't disperse very far.

They're really limited to these mountain peaks, which we can think of as almost like islands in the sky.

In order to survive over time, really, they just hunker down.

Their strategy is to persist.

- So this is a small Fraser fir, and this is a good example of a small sapling that could be 40 to 50 years old that's in the understory here, just waiting for its opportunity to get sunlight and grow to the canopy.

[gentle music] - [Misty] When we're walking through old growth forests, we often think about the trees as being old, but many people don't think about the herbs.

This patch of galax took decades to establish.

It's another reason we need to protect these natural areas and to think about how we can connect them to a resilient landscape.

- [Michelle] Because of the 2,000 foot elevation change from its base to the peak, hiking from the bottom to the top of Grandfather Mountain can be compared ecologically with walking from Georgia all the way to Canada, which is what allows the area to support a huge diversity of species.

- Grandfather Mountain is an international biosphere reserve.

There's over 400 biospheres globally, and they identify the most unique places on the planet.

Here at Grandfather, we have more than 70 listed rare and endangered plants and animals that call this place home.

Many of those are endemic, meaning they're only found in two or three places on the planet.

[upbeat music] - [Michelle] But because they're so specially adapted, these species are threatened by shifts in temperature and precipitation caused by our changing climate.

- [Misty] We don't know how the species are going to be able to adapt over time.

Historically, the earth has warmed and cooled periodically, but the changes that we're seeing today may be happening faster than they happened in the past.

- One of the things that's been interesting the last few years have been really heavy rainfalls in the spring, especially in May.

The net, when you look at the annual precip, it's about the same as it's been in the past, but the way that that occurs is quite different.

We've had two really epic 300 year flood events that have happened in back to back years in May, and of course, that's followed by droughts.

- [Michelle] Warmer temperatures also mean that faster growing species from further down the mountain could creep upwards and outcompete the slower growing species at the top, like the red spruce and Fraser firs.

- Here in North Carolina, there's been a lot of research looking at projections and estimations of how much temperature increase could cause retreat.

We believe about three degrees would cause a 1,000 foot retreat of spruce-fir forest.

So, three degree annual temperature could potentially take spruce-fir forest off the top of Grandfather Mountain with time.

- [Misty] It's so important for us to recognize these places as unique for North Carolina, and to protect them now, because if we lose them, we're not gonna get 'em back.

[upbeat music] - [Michelle] Land conservation efforts are a critical tool for reducing human impact and keeping these unique places around for the future.

Organizations like the Natural Heritage Program and the North Carolina Land and Water Fund work together with local governments and land trusts to establish a resilient network of nature preserves across the state.

- So when we conserve a piece of land, we preserve and protect that land forever.

Grandfather Mountain is remarkable ecologically in its own right, and fortunately, it's permanently protected, the entire mountain.

But it actually well down the valley.

For example, Wilson Creek has its source on the highest point of Grandfather Mountain and falls 4,000 feet vertically down into what is some of the best trout water in the Southeastern United States.

This landscape scale conservation, like Grandfather Mountain and the areas below it in the valley, are so important because it gives plants and animals a migration corridor during this time of intense stress with climate change.

- [Michelle] And beyond protecting our prized natural areas like Grandfather Mountain, land conservation can actually play a critical role in mitigating the effects of climate change.

- [Misty] North Carolina has been protecting land for many, many years, and we've long recognized the value of land conservation for protecting wildlife habitat, for protecting these unique ecosystems.

What we've learned more recently is that land conservation also helps reduce the effects of climate change by pulling carbon dioxide out of our atmosphere and storing carbon in our trees and our soils and below ground.

- When you think about climate change and you think about the things that are happening in our world, there's some optimism there, that we at least have protected the place so that we can allow those changes to play out.

- [Michelle] You can watch more "Sci NC" episodes any time on our website or through the PBS streaming app.

- North Carolina's coast is known as the graveyard of the Atlantic.

The shifting sands, the unpredictable weather have contributed to hundreds of shipwrecks off the coast.

Well, it turns out that sand tiger sharks have moved into those shipwrecks, and they are now the top predator living there.

And that's not a bad thing.

Researchers have found that on wrecks where sand tiger sharks hold sentinel, there is a greater variety of reef fish, and that's a good thing for people and sharks.

[gentle music] - You can't swim with a shark without just being fascinated by how this animal has evolved over the years of their tremendous success story, and to see how they've adapted in so many ways, there's so many species of sharks, that it's just, to me, a subject that there's no end of questions to ask.

- [Frank] And to answer some of those shark questions, I'm in the ocean tank at the North Carolina Aquarium on Roanoke Island.

Yep, that's me, and that's Shawn Harper, the aquarium's dive safety officer.

And those are sand tiger, nurse, and sandbar sharks.

Harper says the sharks' behavior in the tank mimics their behavior on the wrecks off the North Carolina coast.

- [Shawn] Very indicative of what you would see here, the sand tigers, other shark species such as the sandbar sharks, are swimming around the wrecks.

- [Frank] And that's why I'm in the ocean tank.

More on that in a moment.

But first, let's go off the North Carolina coast, where more than 3,000 shipwrecks dating back to the first English settlements are found on the ocean floor.

Treacherous weather, ocean currents, shifting sandbars, and even world wars, gave the North Carolina coast the nickname, the graveyard of the Atlantic.

But those wrecks have become havens of ocean life, especially for sharks.

- The history of the wrecks is one very cool aspect of it, the marine life that are associated with the wrecks.

I'm a biologist, so that really attracts me.

And the fact that you can see these natural aggregations of large numbers of large sharks and be swimming, you know, like, shoulder to shoulder with them, is just, you know, there's not many places in the world that you get to do that.

- [Frank] There are about 73 species of sharks that live or pass through North Carolina waters every year.

- [Shawn] So it's not a scary aspect for me.

I'm always aware of their space and try to not encroach on them to startle them, or to make them aggravated in any way.

- [Frank] But it's the sand tiger sharks that really intrigues scientists, and it's not just because sand tiger sharks are the predominant species on the wrecks.

- Where these sharks go, when they come back, how long they hang out, do they move from wreck to wreck or stay?

We do know just from where sand tiger sharks tend to aggregate and even watching their behavior in our aquariums and stuff that they do like to be near structure.

They don't seem to like to be out in the wide, open ocean.

- [Frank] It turns out sand tiger sharks not only like to hang out on the shipwrecks off North Carolina's coast, scientists say the wrecks appear to play an important role in a sand tiger shark's lifecycle.

- We're catching almost all big females on these shipwrecks off of North Carolina.

This is interesting.

I'm actually a veterinarian, and so one of the tools that we use a lot for aquatic animals is ultrasound.

'Cause ultrasound relies upon sound waves, it works really well in water.

We ultrasound fish and sharks all the time in our care, in our aquariums.

So we were ultrasounding them, and not only are most of these sharks that we are catching off the wrecks in North Carolina big females, but most of them were pregnant.

So now we have a whole other big question, okay, why are they all pregnant, and why are we not catching females that aren't pregnant?

Why aren't we catching males?

- Some of these females that are gestating are potentially hanging out on these wrecks for longer periods, whereas the males might be passing through seasonally.

And then other females that are taking their break from pupping might be also migrating through.

- [Frank] Female sand tiger sharks give birth after a 12 month pregnancy.

The eggs hatch inside the mother.

There are normally two offspring.

- There's two big questions.

We don't really know where they mate, and possibly even more important from a species standpoint, is we don't know where they pup.

It appears that these wrecks are what you might call a gestation ground.

So for whatever reason, this is where these pregnant females, one of the things we have learned, we do know about sand tiger sharks, is that they have a biennial or triennial reproductive cycle.

So they get pregnant one year, then they take one or two years off to resume their energy stores.

So those non-pregnant females are living somewhere else in those off years.

- [Frank] North Carolina Aquarium researchers are joining with scientists at aquariums and universities along the East Coast to better understand sand tiger shark behavior.

Part of that research involves catching the sharks and inserting a tiny tracking device into the shark's underbelly.

- This is the transmitter that is inside the sand tiger shark.

These would last for up to 10 years.

So once a shark is tagged, we can follow that animal for quite a long period of time.

- [Frank] Receivers to record the shark's movements are attached to shipwrecks.

There are 39 receivers on coastal shipwrecks off the North Carolina coast.

- This is actually the acoustic receiver.

It's essentially like a little hydrophone, so it's listening for pings from the acoustic tags that are on the sand tiger sharks, as well as other species of fish that researchers have tagged.

So it's listening and then recording.

Up here is the hydrophone at the very top.

So that's where the signals are being received.

Inside here is basically the electronics that are recording and storing all that data and the batteries that keep it running.

- [Frank] Some early findings indicate sand tiger sharks are migratory, with a range from Georgia to New York, and they swim from structure to structure.

- [Emily] They also tend to follow temperatures a lot, so we don't know if something has to do with the thermoclines in North Carolina.

We're very close to the Gulf Stream here in this area where these wrecks are.

We don't know exactly, but that's part of the things that we're trying to tease out from the information of timing and movements and when they come and stay on the wrecks, and when they leave.

- The sand tiger sharks have been a staple of public aquariums for as long as I can remember.

They do well in aquariums.

But for as long as we've worked with 'em, there's still gaps in our knowledge about these animals, and so I feel like it's kind of a way that aquariums, public aquariums, can return the favor.

- Which brings us back to the aquarium's ocean tank.

I'll admit I was a little nervous, even with Shawn diving with me, but I was mostly in awe watching a creature so graceful, so powerful, so beautiful, despite the teeth, and so mysterious.

Want more "Sci NC"?

You can find these stories and more on our YouTube channel.

Like and subscribe.

Thanks again to the aquarium for an experience I will not forget.

Now to a bird that is difficult to spot, but you can definitely hear.

The red-cockaded woodpecker calls North Carolina's longleaf pine forests home.

Trouble is, as science producer Michelle Lotker explains, these endangered birds need old living pine trees to nest in, and those are hard to come by.

- Today we are in the beautiful Sandhills Gamelands.

We are here to basically find some red-cockaded woodpeckers.

So we call this device a peeper pole, and what it does is that we have a camera up here.

This pole extends until it reaches the cavities, and once we have it in there, it will allow us to see what is inside.

- [Michelle] Lauren is part of an extensive team of researchers monitoring the endangered red-cockaded woodpecker in the Sandhills of North Carolina.

- So I see three nestlings.

Around day 20, I'll be able to come back and specifically see how many have a crown patch or not, and that will tell me how many males and how many females I have.

- [Michelle] The data Lauren collects on this nest and others will be added to one of the longest ongoing vertebrate studies on the planet.

In the early 1970s, the red-cockaded woodpecker was listed as a federally endangered species.

[gentle music] - When monitoring began in 1980, population levels in the Sandhills were relatively low.

- [Michelle] Red-cockaded woodpeckers are in the Sandhills because of the longleaf pine forest.

- [Brady] Red-cockaded woodpeckers are a unique species in that they excavate their cavities in live old pine trees.

- [Lauren] Specifically, the longleaf pine is one of the sappiest pine trees out there, and that's great for the RCW because they use the sap as a defense mechanism.

They will drill resin wells into these trees, which will flow with sap.

Their biggest predator is the black rat snake.

What the rat snake will do is it'll try to climb the pine tree, it'll get sticky with sap, it'll fall to the ground, and it'll be sappy for a few days.

- [Michelle] To gather data about red-cockaded woodpecker nesting success, Lauren also climbs these sappy trees, fortunately, with the help of ladders and some other specialized equipment that helps her take baby birds out of the nest to add some fancy jewelry to their legs.

- So we have our pullers.

Helps us pull out the nestlings.

Oh, hello.

[woodpecker chirps] Hi.

Hi, hi, hi.

So once we pull the nestlings, we wanna check in the cavity to make sure that we got 'em all.

To see, also, if there's any eggs present.

Come back down the tree, band the chicks.

So, each group of birds has a specific band combo.

We call it a clan combo.

So they have two bands, an aluminum band, and a color band on their right leg, and they have three bands on their left leg.

Once we band 'em, we wanna get a weight on 'em.

So we put 'em in a little weight bag, get a weight, and once we do all that, we climb back up the tree, put the chicks back in.

We try to do it butt first, and we try to do it with the heaviest chick first, 'cause if we have a lighter chick, that way they might get, you know, the next bug that's coming in.

We take our mirror and our light back out, put it back in, make sure that they're all down there safe and sound, and we climb back down the tree.

- [Michelle] The colorful bands stay on the birds as they grow and allow researchers to follow specific birds as they leave the nest or fledge.

They use high powered scopes to spot the tiny leg bands.

- [Brady] Here they come.

Incoming.

That orange aluminum again.

Big babies.

Oh, there's number two.

- Ah.

- [Brady] That was dark green on the right.

- So, each cluster has their very own band combo.

That's how we tell them apart.

And each individual has a different color band on either leg.

- Just two adults so far.

- So far.

Looks like a third adult, aluminum over red.

- [Brady] Cool.

- [Lauren] So we've counted three adults here so far.

- [Michelle] There are more than just one pair of adults around this nest because red-cockaded woodpeckers are cooperative breeders.

- [Lauren] So they have a very unique social system.

They live in these family groups which are made up of a breeder male, a breeder female, and what we call helpers.

- [Michelle] Helpers are usually male, and they assist with everything from incubating the eggs to defending the territory, all in the hope that they might one day inherit it and have their own nest.

For a longleaf pine tree to be the right size for a red-cockaded woodpecker nest, typically it needs to be about 100 years old, which can be hard to find.

- Historically, through logging up until the beginning of the 1900s, almost the entire southeast was clear cut for railroad boat making, any number of things, turpentine.

So now we're, say, 100 years post that main clearing in the southeast, we're getting a lot of trees that are coming into perfect age and internal structure where the birds can make their own natural cavities.

To make a natural cavity, these birds have to excavate through the bark, a thin layer of cambium, the sap wood, and then excavate a cavity that's maybe three inches around by seven inches deep in the heartwood of the tree.

And that can take anywhere from one to 12 years to make one cavity.

- [Michelle] One solution to help populations grow more quickly?

Artificial nesting cavities.

- This is an artificial cavity.

It's one of the most important tools we have for bridging the gap between a younger forest that may have bigger trees and more of an old growth state where the birds can create their own cavities.

This is installed in a rather large tree with a chainsaw, and the birds will take to these almost immediately.

I've put them in before and had them use them that same night.

They've been a crucial tool for getting us to this point in our recovery journey.

- [Michelle] And it's an ongoing journey, although populations have improved significantly since the 1970s.

- [Brady] Since then, we've had really great conservation successes by growing the populations where we can do prescribed fire and artificial cavity work.

But they are what's considered a conservation reliant species, and that all the work that we're doing is gonna need to continue to happen going into the future.

- [Michelle] Fire maintains longleaf pine ecosystems by clearing out the understory.

Unique species in these forests, like this wiregrass, are especially adapted to rebound quickly after a fire.

[upbeat music] As work continues to be done to maintain their habitat, researchers like Lauren are starting to ask questions about how these birds will adapt to a changing climate.

- [Lauren] Climate change research on the RCW is just sort of ramping up.

There have been studies that have seen that there is a climate induced shift in nesting earlier.

With this climate induced shift, we are seeing this increase in hatching failures and brood reduction.

- [Michelle] Brood reduction means less chicks survive from each nest.

Based on the trends they're seeing further south, researchers are worried populations in the Sandhills will be impacted next.

- [Lauren] It all goes back to the pine trees.

They have to go where the living pine trees are.

Looking at that and where the climate change is impacting them, they sort of kind of don't have a choice, because this is their home, they're endemic to this ecosystem.

We just have to keep doing what we're doing with the monitoring and the management and just keeping up the ecosystem of these birds.

- [Michelle] Follow us on Instagram for beautiful images of North Carolina and cool science facts.

- And now to the archives for a quick look back at one of our most requested stories.

You probably know what a crayfish looks like, and you can imagine what nasty water is like.

Producer Rossi Isler shows us just how scientists may finally have figured out how a crayfish survives in nasty water.

- [Rossi] Hello, my little crayfish friend.

These fresh water lobster lookalikes are all over the south, even in some of the nastiest waters.

- Boy, oh, boy, I have seen crayfishes in some pretty disgusting waters.

- [Rossi] How they manage to live in those waters is a mystery.

But Bronwyn Williams, our resident crayfish expert, says the tiny worms that live on crayfish could be helping.

- There's one.

Oh, hey, little dude.

Okay.

So they have an adhesion point, their butt sucker, if I can say that, that they use to attach to the crayfish.

- [Rossi] Crayfish worms are completely dependent on crayfish for their reproduction.

- They actually need to deposit their cocoons with live embryos onto a living crayfish in order for that embryo to develop and then hatch into a worm.

- [Rossi] And what does the crayfish get out of this?

- What we see in the digestive tract of these crayfish worms, they are grazers for the most part.

So you'll find diatoms and algal material, anything that would really land and settle on that surface of the crayfish.

So they're effectively cleaners.

The crayfishes that I've collected that are just the most fouled, you know, just have the most sediment all over them, and even packed into the gill chambers, I don't find a single worm on them.

So, cause and effect.

Obviously, I mean, that's anecdotal.

- [Rossi] Worms aren't even the only animals living on crayfish.

They're also home to these little shrimp-looking things called ostracods, which seem to live in perfect harmony with the crayfish worm.

And unlike other ostracods, this species has developed claw-like hooks, presumably to latch to the crayfish's shell.

So, one crayfish literally contains multitudes.

- [Bronwyn] You can think of crayfishes as ecosystems all on their own.

- [Rossi] Also, here's a baby crayfish.

You're welcome.

Check out our weekly science blog to take a deeper dive on current science topics.

- And that's it for "Sci NC" for this week.

If you want more "Sci NC", be sure to follow us online.

I'm Frank Graff.

Thanks for watching.

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