- [Announcer 1] Quality public television is made possible through the financial contributions of viewers like you, who invite you to join them in supporting PBS NC.

[piano intro] - Hi there I'm Frank Graff.

It's not just humans and birds who migrate to find more comfortable temperatures.

It turns out sharks do as well.

You can learn a lot from man's best friend and we'll meet the original engineers.

We're talking about getting comfortable, next on "Sci NC".

- [Announcer 2] Funding for "Sci NC" is provided by the North Carolina department of Natural and Cultural Resources.

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

This is what hundreds of black tip sharks look like from a few hundred feet above the coast.

It's an extraordinary migration from Florida to New England, and yes, those sharks eventually pass North Carolina's coast.

Science producer, Michelle Lochner, tracked down the scientists who are tracking down the sharks.

- Paul beach approach, Skyhawk flight two, eight, zero, Delta checking with you northbound along the shoreline 500 feet.

Got beautiful, clear water today.

Great visibility.

We can easily see the sharks.

There's a bunch of sharks right there.

A dozen or more right there.

There's another shark southbound along the beach.

There's a bunch of sharks here.

They're all going south.

That's cool.

There's a bunch of people in the water with the sharks.

People that have no idea there's sharks there.

- [Michelle] It's winter in South Florida and along with the tourists, black tip sharks are flocking to the shore.

These sharks migrate up and down the Eastern seaboard each year, passing through North Carolina's coastal waters in the spring and Dr. Stephen Kajiura has been setting this migration for 12 years.

- [Stephen] We're flying down here along the beach in South Florida, and we're nice and low 500 feet off the water.

And we're flying fairly close to the beach here.

It's simply because that's where the sharks are.

So we're seeing sharks here, but it's in the range of a few to maybe dozens.

It's certainly not in the range of hundreds to thousands like we've seen in the past.

- [Michelle] The clear waters off South Florida's coast allowed Dr. Kajiura and his students to count black tip sharks by flying a small plane from Miami, up to Jupiter, with a high definition, camera mounted out the window.

- The black tip sharks that we've worked with down here are an average sort of shark.

What you typically think of when you think of a shark, they have a maximum size of about two meters or so.

They have a shark pointy nose.

They're very smooth and streamlined, and they are fast sharks.

These sharks are feeding primarily on little bait fish.

They have sharp pointy teeth, which are very good for grasping slippery fish.

And they're making these long distance migrations along the coast and that's what we're interested in looking at.

What are these sharks doing after they leave South Florida, as they're migrating all the way up the US Eastern seaboard.

- [Michelle] Black tip sharks or Carcharhinus limbatus, are social and they migrate and hang out in groups, usually in the shallow waters near shore.

Right where beach goers like to swim.

- [Stephen] And that's what was sort of the impetus for this whole study.

Why are there so many sharks right where the swimmers are?

- [Michelle] It turns out black tip sharks have several reasons to hug the coast as they migrate north and south.

They primarily eat small bait fish.

And these fish like to hang out in the shallows.

Also, being a shark doesn't automatically put you at the top of the food chain.

Black tips make a tasty meal for other larger sharks, like hammerheads.

By staying near the shore, they can often dart into shallow waters where their predators can't follow.

- [Stephen] It's a good place for the sharks to be, they can eat and they can avoid being eating.

- [Michelle] But we don't know all of this just from aerial surveys.

- [Stephen] The aerial surveys are great because it gives us the big picture of what's happening along the whole coast of Southeast Florida here.

But then you need to get down on the water to actually work directly with their sharks.

[upbeat music] - [Michelle] First, you have to find them.

[drone buzzes] - Can I see a shark?

1, 2, 3, whole bunch of sharks right here.

Cool.

We're gonna go right up here.

We're gonna start dropping blocks in and we're gonna catch some.

- [Michelle] Dr. Kajiura and his team of students and volunteers deploy baited hooks attached to concrete blocks and floats in a line along the shore and wait for a shark to take the bait.

- [Stephen] You got tension.

All right, we got a shark.

- [Man] Right under, can you get the tail there.

[shark splashes] - [Cameraman] Does it look healthy?

- Yeah, it looks healthy.

- [Cameraman] Sex?

- Nice big male.

- [Cameraman] Male, okay.

[upbeat music] - [Michelle] Once the shark is secure alongside the boat, they quickly take measurements, a small tissue sample for DNA analysis and attach an identifying tag, sorry, buddy, before releasing the shark.

- If you were to just look at the aerial survey data, you only get data for a few months when the sharks are here, but we don't know what happens after they leave.

- [Michelle] Using satellite or acoustic transmitters, Dr. Kajiura and his team can track an individual shark for years, collecting valuable data about their migratory patterns.

Satellite tags are fixed to a sharks dorsal fin, communicate with an orbiting satellite every time that fin breaks the ocean's surface.

- And so you can literally get an email to say, tag number 1, 2, 3 was detected at this latitude and longitude, and you're able to track the movements of these sharks in real time.

- [Michelle] Listening stations up and down the coast, pick up signals from acoustic transmitters.

A network of scientists share the data.

- [Stephen] For this sort of work, where you're talking about movements along an entire eastern seaboard of the United States.

This is well beyond the range of what one lab can handle, but with so many individual labs all the way along and all pooling our data together, it enables everyone to benefit.

And we're able to look at these long distance migrations that would simply be impossible to study any other way.

[upbeat music] Really fortunate that shark research has been conducted along the east coast of the US for many decades now.

And we have long term data sets going back 50 years or more.

And what this enables us to do is look at the effects of things like global climate change on the distribution of these animals.

And we know now that these sharks are spending the winter down here, and then as the water temperature starts to warm up, they'll migrate their way farther up the coast.

They get as far north, as about Long Island by September.

So they're making this long distance migration from South Florida, all the way up to New York.

And then back again.

And remember these sharks are about the same size as us, right?

They're about the same size as the human.

That's a long haul for us to walk that far.

And these guys are doing it twice a year.

- [Michelle] A long-term data set like this allows researchers like Dr. Kajiura to see patterns and shifts in the migration.

- [Stephen] Even in maybe a 10 year span, we've seen a dramatic decline in the number of sharks that are coming down here every winter.

And it's tightly correlated to water temperature.

What you'll see here is that half, that 50% of their time is spent at a temperature between 22 and 23 Celsius.

And 85% of their time is spent in just a three degree temperature band.

So they have a very narrow thermal preference.

They really like that particular range of temperatures.

And that's what they're following.

They used to go from south Florida up to about Cape Patris North Carolina in the summertime, but now it's extending all the way up to New York.

- [Michelle] It's not clear yet what this change in black tip shark distribution will mean.

Overall, even though their migration pattern has shifted northward, the black tip shark population is stable.

In fact, they're even fishes commercially, but thousands of sharks moving into different coastal territories is likely to have an impact on coastal ecosystems and their inhabitants, human and fish alike.

- [Stephen] When you think of these sharks going farther north than they have, historically, they're gonna be encountering different fish up there.

And the fish are not accustomed to having literally thousands of these black tips coming in every summer.

And so it's gonna be a dramatic change to the ecosystems farther north.

It's gonna be a change to the ecosystems farther south here.

If you don't have that annual influx of these top level predators taking advantage of the little bait fish buffet, you don't know what's going to happen to the animals that are down here that are not being eaten.

So there's a lot of potential for cascading effects through multiple ecosystems and multiple trophic levels.

And it's just gonna be interesting to see what actually happens.

[upbeat music] What I would like people to remember is that there are literally thousands of sharks right in our beaches and very few people get bitten.

And so these sharks are not out to get you, the sharks are there, they're doing their own thing.

You're in the water as well.

And you're having a good time and I encourage you to keep going in the water and having a good time.

Don't be afraid of the fact that there's sharks in the water.

You've probably been swimming those sharks before and just didn't know it.

- [Michelle] Wanna take a deeper dive on current science topics?

Check out our weekly science blog.

- While those sharks migrate to more comfortable surroundings, beavers build comfortable houses.

In fact, you could call beavers the world's first engineers and as producer Rossi Isler explains, that has implications for other animals and people.

- [Rossi] North America's relationship with the beaver has been somewhat tumultuous.

Starting in the 1500s humans almost eradicated them from the continent for their fur.

But when we did that, we fundamentally altered the landscape because it turns out beavers are one of nature's most prolific engineers.

- When it comes to beaver, there are kind of two main camps about beaver.

People either, oh, love them.

People like me, they're a Keystone species, and ecosystem engineer.

They're important.

They have this huge role in the landscape.

We should love and appreciate them.

And then there are people who see them as 70 pound rats who flood their yards and they needed to be relocated and gotten rid of.

- [Rossi] Nuisances or not the wetlands and ponds made by beavers, create habitat for countless other creatures and protect ecosystems from devastating wildfires.

Today, there's a movement to bring beavers back and restore what we lost when we almost ousted the beaver from our world.

But first, researchers have to document the difference that beavers are making.

- One fifteen.

- [Michelle] That's why UNC Chapel Hill Scientists are studying beavers in urban watersheds, including the elderly Creek in Durham, North Carolina, because believe it or not beavers do exist in the city.

Take this beaver pond behind Compari Foods, but humans also build ponds.

Urban landscapes are dominated by retention ponds.

They're there to control water.

- When you pave the landscape, then there are other problems and those problems are flash floods.

So every time it rains, water is not infiltrating, but just running over over the parking lot or over the road.

And it moves very quickly.

The retention ponds are built to take the energy from the water and store that water in different places.

So if you look at new development, for example, nowadays, the first thing they do is they take down some acreage of forests.

They put roads and they build the retention ponds.

- [Rossi] Retention ponds might not always be pretty, but they work.

However, they come at a cost.

- [Diego] So there's lots of concrete that goes into it.

There's the plowing.

There's everything that takes place to build these massive structures and then cities have to manage 'em.

They have to clean them so that they function properly.

And they function for decades as intended.

- [Rossi] Beavers are controlling water too, but they're doing it for free.

- So my little elevator pitch is that we are comparing bio retention ponds and beaver ponds because if you think about it, they're really almost the same thing in structure.

There is water coming in that would be a single flow, but then there is a dam that stops it.

And it just varies by retention ponds, a human put that dam in there.

That beaver ponds, a beaver put the dam in there.

- [Rossie] But let's back up.

Why are beavers doing this?

Why are they always making ponds?

Beavers build dams so they can have a deep enough pond for their lodge, a dome shaped home to stay warm and protected from predators.

They access the lodge, using a tunnel beneath the water.

Some of these dams are impressive, including this half mile long one in Canada that you can see from space.

The downside of beavers is that sometimes they make ponds where you don't want ponds, but they're considered a Keystone species because they create so much habitat for their wildlife.

Things like frogs, fish, invertebrates, which in turn feeds larger mammals and birds.

And then there's the benefit to us.

In some places, beavers are storing enough water to protect areas from wildfires and severe droughts.

Problems that are only getting worse with climate change.

All these benefits are giving researchers the incentive to study beavers more closely.

- [Diego] How do we manage them in a way that is sustainable, that is providing an ecosystem service to us?

And it really, it will have to be studied on a case by case basis.

- [Rossie] The team is trying to find out if beavers can do a better job than retention ponds at cleaning and filtering the water.

So they're taking lots of measurements that compare the two, including one that measures the ability of both types of ponds to break down nitrogen and phosphorus, nutrients that cause deadly algal blooms.

They're still collecting and analyzing data, but one thing is certain, beavers are amazing free labor.

- I mean, if you think about it, we're spending so much money to build this bio retention infrastructure and we're spending so much money to relocate and hunt beaver but they're doing the same thing.

So I think even for people that don't see them as cute adorable creatures, if you can see it from a logical perspective of, "oh, maybe it would be worth taking the time, and energy to use these to our advantage."

- [Rossie] Do you want to explore more cool science facts and beautiful images of North Carolina?

Follow us on Instagram.

- There's a good reason dogs are called man's best friend.

We've been friends for a while.

Genetic evidence shows dogs were domesticated in Eurasia between 14,000 and 29,000 years ago.

Most likely to help with hunting.

But as producer Rossi Isler shows us from the Duke Canine Research Center, we still have a lot to learn.

- [Rossie] Dog owners will be the first to tell you how smart, how cute and how unique their best boy or girl is.

And evolutionarily speaking, they're right.

Our relationship with dogs spans thousands of years and has fundamentally changed their evolution as a species.

They are one of the few animals on the planet that's adapted to communicate with us.

Like those adorable pleading eyebrows, dogs developed a specific muscle, the levator anguli oculi medialis to achieve what scientists call the inner eyebrow raise, presumably because humans favorite dogs that could make those sad puppy dog eyes.

Dog's ancestor, the wolf, doesn't have this muscle and that's just one of their skills.

- Happy look.

So we found out that dogs are really good at reading cooperative gestures.

Like if I point to something to help you find it, that's a cooperative gesture and dogs are very good at understanding that.

- [Rossie] That ability to read human social cues is very rare in the animal kingdom.

Even our closest relatives, the chimpanzees don't have it.

Hannah is studying the finer details of how and when puppies achieve these skills at Duke's Canine Cognition Center.

One way to understand dog evolution is to compare these puppies to their closest ancestor, the wolf.

- So as dogs were evolving from wolves, one hypothesis is that they were selected for friendly temperaments, whether they kind of self-selected at first, the ones who are most friendly, least aggressive or fearful towards humans, would've been the ones who more successfully came into human camps and were able to benefit from that.

And then maybe further on down the line, people were intentionally selecting the most friendly ones to keep as pets and help and as hunting companions and things like that.

- [Rossie] The research team hypothesized that if dogs were selected for friendliness, dog puppies would show an innate ability to communicate with humans compared to wolf puppies.

So they compared a group of Wolf puppies to a group of dog puppies.

The wolf puppies were smothered in love from humans, bottle fed, snuggles at night, constant 24/7 human companionship.

The dog puppies had less human interaction.

They were raised in a kennel with most of their early weeks spent with their mothers.

Then they tested both groups with a variety of games, including one called the unsolvable task.

- [Hannah] Though, for this one, we have a clear Tupperware container and we'll put a piece of food in the container and close it so that they're not able to open it on their own.

And then we just measure how much eye contact the puppy makes with the person.

And so what we found is that dog puppies on average tended to make more eye contact than the wolf puppies.

The dog puppies might try to get at it, scratch at it, bite at it for a little bit and then they would often sit back and just look up at the person like, "please help me."

Whereas the wolf puppies, they would just keep trying and trying on their own.

Maybe sometimes they just wander away and lay down and they didn't make as much eye contact with the human as the dog puppies did.

- [Rossie] So even without that extra human attention, dogs still have the ability to rely on human social cues.

The study supports the idea that dogs evolved from wolves as the friendliest and most social wolves were allowed in human camps, giving them an advantage over the more surly wolves.

- And there's even some evidence that dogs have kind of hijacked, they call it our emotional pathways, where making eye contact with them releases the same kinds of bonding hormones as it does making eye contact with a baby or a significant other or something like that.

- [Rossie] These social communication skills also make dogs the perfect service animal.

Duke is using the latest research on canine cognition to improve service dog training.

- So dogs have a lot of jobs now.

They are helping so many people, they're better than technology in a lot of instances.

There's not just service dogs, but they're working dogs and every organization has the same problem is that there's just not enough of them.

I think just TSA has like a 20,000 dog shortage.

There are millions of people who could use them.

- Yes, there it is.

Good job, buddy.

- So our question is, well, how do you scale?

And so what we do is that we take the puppies from eight to 20 weeks, which is their period of most rapid brain development.

And we give them all these kind of like just cognitive aptitude testing, kinda like a little head start program.

And we're trying to find out what makes the profile of a service dog.

So we can at a very young age take them and then run them through a series of games and then figure out, well, what dog is gonna be best for which job.

- [Rossie] Duke works with Canine Companions, a non-profit that provides service dogs for free, but it takes years of intensive training and lots of money to get these puppies ready for service.

- These dogs truly allow people who otherwise could not live without the care and help of another human, allow them to live independently.

People who can't bend down to pick up items that they drop, people who can't open a door or open a refrigerator, or turn on and off a light.

These dogs can do all of that.

They are incredible and amazing.

If we can better identify which dogs are more likely to make it, then we can invest more into those dogs and get more dogs to more people.

There are so many people on the waiting list that are in need of these dogs and it's really fulfilling to know that these dogs are gonna change someone's life.

So I love it.

- [Woman] Hey, parents, teachers and homeschoolers, looking for lesson plans?

You'll find free interactive ones about all types of science covered by "Sci NC" online.

- In a show about getting comfortable.

Let's head to the ocean now because collecting sea shells makes us comfortable, but did you ever wonder how they're made?

NC Culture Kids shows us.

[upbeat music] ♪ - Hey everyone, I'm Emily and I am here at the Rachel Carson Reserve.

Here to talk with educator Christine from the North Carolina Maritime Museum at Beaufort to talk about seashells.

Thanks for taking me out here, Christine.

- Oh, glad to have you.

It's a beautiful day so a great day to come visit the beach.

- Awesome, so my first question for you is where do seashells actually come from?

- They come from a lot of different animals.

Animals actually have lived in these shells and built them up around them.

So you can see here I have a clam and there was a creature that lived inside this shell and as he grew up, actually built this up around them.

- Interesting.

So how are shells made exactly?

- So these animals that are living inside of them are actually filter feeders.

So what they do is they'll filter their food out of the water and pull the things that they need for their body and for their shells and build up the shells as they go.

Now what's really cool is on some of these shells.

Let me find a good one in here.

You can see these beautiful lines on them kind of, and they're growth lines.

So as this creature has got started off minuscule here and gotten bigger and bigger and as material becomes plentiful, meaning there's a lot of nutrition in the water, they'll build up the shell and their bodies will grow as well.

So these are actually growth lines on the outside of the shell that you're seeing here.

- Oh, so it's kind of like rings on a tree.

- Similar to rings on a tree, the major difference being where on a ring on a tree, you know that happened on a yearly basis.

So it helps you age them.

This kind of happens more on a as food is available basis.

On earth we've documented, I believe it's over 70,000 different species of shell dwellers.

So the most common type style shell you're gonna see out here is gonna be a bivalve, creature that has two shells.

They live on the inside and they're able to open and close these shells as they need.

So this is a clam.

Once again, you can see those beautiful rings kind of indicating how minuscule he was when he started and then as he grew, but then another very common one, probably the most common you're gonna find in our area is the oyster shell that's gonna be out here.

And these, what's cool about them is they are bivalves and they actually will live on top of each other.

[upbeat music] - So you mentioned that you see more of these commonly here in North Carolina, but does North Carolina have a state shell by any chance?

- We do actually.

We have in 1965, we became the first state to have our very own state shell.

Our shell is known as the scotch bonnet and what's cool is they actually chose the scotch bonnet to be our state shell to honor the Scottish settlers that help settle North Carolina.

Now, if you find a shell like this on the beach, as tempted as you might be to take that home with you, always make sure you check inside the shell, 'cause even if the original owner of that shell is not in there, it is very common to find the crabs that have decided to live there.

- So Christina, as I'm holding onto this shell and looking at it, I'm remembering when family and friends would tell me as a kid that if I brought the shell up to my ear, I could hear the ocean.

Now, if I'm out back home inland, I'm probably not gonna actually hear the ocean.

So how does that work exactly?

- So it's really a cool phenomenon because usually works best with a welk shell, usually bigger than this one.

And when you put it up to your ear, it cups your whole ear and you've got a pretty strong artery there.

So what's happening when you cup your ear like that is you're hearing your own pulse echoing through that shell.

And it sounds very much like the waves, unless you're a hardcore mermaid believer and they say it's a shell phone and you're listening to the mermaids themselves.

- Yes.

Absolutely.

- Yes you're definitely more likely hearing your pulse and your heartbeat.

So we have welks here.

So this right here is something that you'll find commonly on the beach and this is a welk egg case.

So little baby welk are in there and when they're born, they're actually born with their shells already.

And I have in this little case here, some newborn welks and you can see how small, they're almost borderline microscopic.

- Yeah that's so awesome.

[upbeat music] - And that's it for "Sci NC" for this week.

Be sure to check us out online.

I'm Frank Graff.

Thanks for watching.

[upbeat music] ♪ - [Announcer 2] Funding for "Sci NC" is provided by the North Carolina Department of Natural and Cultural Resources.

[upbeat music] ♪