[birds chirping] - [Narrator] The dawn of a new day across Eastern North Carolina's farm fields.

But as light fills the landscape, wings erupt from those fields and fill the sky.

[wind blowing] And swell and settle like a living breath.

And then you hear the sound, floating through the air, the call of tundra swans and snow geese.

[birds chirping] - It's just a fantastical experience.

I don't know, I've never seen numbers like that before where I see literal seas of white out on the landscape and they travel such a long distance that I think it's just that whole wonderment of like, how does it happen?

Why are they here specifically?

And like, how are they just congregating like this?

And it's just so beautiful to see.

So people that are really into wildlife are really into birding.

I mean, they get to see a species that's normally found in the tundra coming all the way to Eastern North Carolina.

I just think it's just like one of those kind of like magnificent, like awe inspiring type moments to see them out here.

- [Narrator] The swans and geese are the show birds but 10s of thousands of migratory birds, 19 species in all spend from roughly November through February at the Pocosin Lakes National Wildlife Refuge and five other refuges along the North Carolina coast.

- I absolutely love it.

It's just, so I get excited to give programs 'cause I'm like, oh, I get to be outside and I get to see this really cool event.

Absolutely, this is like my favorite thing to do.

[person laughing] - [Narrator] And most of the birds eventually find their way to the Pungo Lake area of the Pocosin Lakes Refuge which is where Katrina Ramos leads visitors and shares her love of nature.

[birds chirping] - A lot of these behaviors, you're just seeing them kind of relax out on the water.

They don't really have to worry about a predator out here in the middle of the water unless it's another bird of prey.

So it's the most northern part, like if you think of like where Canada ends or where Alaska ends towards the north, that is the area.

Yeah, that's where they'll build their nests and have their babies all throughout the summer until they're ready for their next migration season down here.

- [Narrator] Ramos is with the North Carolina Chapter of the National Wildlife Federation and works as an outreach coordinator with the refuge.

- I am also like a super big dork.

[person laughing] So I'm like, look at it, can be the same thing happening over and over again and I'm just like, wow.

- [Narrator] And as if on cue.

- [Katrina] Look at that entire flock that just went up.

- Where?

- Do you see the white in the sky right there?

- Yeah, oh.

- Yeah.

- [Narrator] That white cloud on the horizon is not a cloud at all.

- [Katrina] Yeah.

[person laughing] - [Speaker] Oh my gosh.

- [Katrina] It is a legitimate cloud on the landscape.

It is, yeah, right, isn't it so cool?

- [Narrator] Tundra swans are temperature sensitive, not too hot, not too cold.

They nest in the Arctic, but then head south for the winter.

- [Katrina] Once they start realizing, okay, we've had our fledglings, the temperature's not kind of going where we want it to be.

We're gonna start following that colder temperature down the east coast.

Granted, some of them do go down that Western Flyway but they're in larger numbers coming down the eastern coast - [Narrator] The tundra swans have flown almost 4,000 miles from the north of Canada.

Scientists have clocked the birds flying at 100 miles per hour, as high as 26,000 feet.

- [Katrina] They're really just eating food, hanging out, just waiting until the tundra's back into the season for them to start nesting and having babies again.

So it's just kind of part of them chasing the cold.

- [Narrator] The refuge is specifically managed for migratory birds.

- So they have a cooperative farming agreement that basically allows farmers that have land out here to farm their crops, as long as it's in agreeance with fish and wildlife on the certain types of crops that they do.

- [Speaker 2] Yeah, I appreciate that.

- Usually those are soybean and corn, and then in return, the farmers leave 20% of their crops for wildlife.

- [Narrator] But that could change.

Habitat loss and climate change threaten all of the migratory birds but especially the tundra swans and the snow geese.

- 1.5 degrees Celsius increase overall in the Earth's temperature, they completely stop overwintering in Eastern North Carolina and they start moving more towards Michigan and the western part of the United States like Utah and Nevada.

We would never see them after we start reaching that one and a half degree Celsius average increase over the entire Earth, we would not see them in Eastern North Carolina anymore.

Hopefully, I don't have to experience that.

I'd be very sad.

[person laughing] I'm really big into being outside, so the fact that I get to take other people outside and show them something as cool as this over and over again is just, I don't know, I'll never get tired of it.

[birds chirping]