Original subtitles

Narrator: For some, it's natural to hang around upside down,

But for this skunk, logic has been turned on its head.

So the question is, what is it doing?

Narrator: In arkansas, thousands of birds turn up dead

For no apparent reason.

Bradley: Something absolutely catastrophic

Happened to them either in the air

Or when they plummeted to the earth.

Narrator: And why is this frog flashing?

It's like a christmas frog.

Narrator: Nature is awe-inspiring,

But sometimes, it just doesn't make sense.

Man: I have never, ever seen anything like this.

Strange animal behavior,

Unexpected events captured on camera.

[ screeching ]

The truth behind them is astonishing.

Woman: My god!

Nature's greatest mysteries solved.

-- Captions by vitac -- www.Vitac.Com

Captions paid for by discovery communications

It's January 1, 2011, and in one town,

The new year has begun like something out of a horror movie.

[ telephone rings ]

♪

♪

I'll never forget the incident in beebe, because it happened

Just after I had relocated to the united states.

Narrator: Beebe is a small town in arkansas.

It had woken up to find around 5,000 dead birds

Scattered over an area of about 2 square miles.

Bradley: It was quite horrific.

This incident came to be known as the aflockalypse.

Narrator: There were so many dead birds,

It took 2 days to clear away the carcasses.

Bradley: Obviously, something absolutely catastrophic

Happened to them either in the air

Or when they plummeted to the earth.

Narrator: Who, or what, had killed these birds?

And if it was something airborne,

Could local residents also be at risk?

In terms of pollution, if it were strong enough

To kill a flock of 5,000 birds,

That's gonna affect people on the ground,

It's gonna affect living things nearby.

Narrator: Residents were worried that whatever had killed the birds

Might harm them, too, so officials had to act fast.

They first studied those most affected --

Red-winged blackbirds.

[ chirps ]

These songbirds have a variety of tunes...

[ chirping continues ]

...And get their name from the males' red-feathered shoulders.

Bradley: The red-winged blackbird is a very striking bird.

There are glossy black plumage on the males

And then these stunning red and gold epaulettes.

When the males are trying to attract a female's attention,

They fly very slow

And tilt these epaulettes up to show them off,

Not unlike the way an airplane would turn its flaps up

For landing.

Narrator: Very dashing, guys.

If you've got it, flaunt it.

[ chirps ]

So, what could have wiped out so many of these

Striking songbirds in one night?

Bradley: Perhaps the most ghastly probability

Is the idea of an airborne toxic event.

Narrator: Worryingly, there had already been some mysterious

Animal deaths 3 days before the blackbirds died

Just a drive away from beebe.

Bradley: An incredibly disturbing precursor

Was the death of 120,000 drum fish in a nearby river,

Giving rise to the possibility that poison was involved,

Perhaps some sort of toxic gas

That had poisoned both the air and the water.

Narrator: It was possible that the birds and fish had been killed

By the same toxin.

Some gaseous chemicals can dissolve in water vapor

In the air.

This can condense into clouds, fall as acid rain or snow,

And run into rivers or the water table.

As a precaution, officials in beebe wore protective suits

As they cleared away the dead birds.

Top experts were consulted,

Including wildlife veterinarian jonathan sleeman.

Because of the high level of concern regarding this event,

We wanted to make sure we weren't gonna miss anything,

Any potential disease that could be transmitted to humans.

We ran all these diagnostic tests looking for poisons,

Looking for parasites,

Looking for viruses and bacteria,

And everything came back consistently negative.

Narrator: The birds weren't killed by disease or something toxic --

A huge relief for everyone in beebe.

Studies showed that when a dam opened upstream,

It churned up the water,

Adding extra oxygen to the river and killing the fish.

But for the aflockalypse, the autopsy results

Were about to reveal something mysterious.

They found a number of birds that had broken bones.

A number of birds had hemorrhages or bleeding

Within internal organs.

They had bruises in their lungs and their liver

And in their cranium.

So all these findings are very consistent

With what we call blunt force trauma.

Narrator: But how could around 5,000 birds

All simultaneously sustain such similar serious injuries?

Clues could lie in one feature of the birds' behavior --

They fly in flocks.

Bradley: Red-winged blackbirds are a very powerful flier.

Flocks of up to 1 million birds

Can be seen in the skies of north america.

Narrator: They're one of the bird species that produce captivating,

Synchronized movements known as murmurations.

Just like schools of fish, whole groups operate

As if with one mind.

Dagmar: A lot of birds in flocks have an ability to communicate

With each other through means we don't yet fully understand.

Like, a flock of starlings will travel left, will travel right,

And the whole flock -- thousands and thousands

And sometimes tens of thousands of birds -- moves in unison,

And how they communicate with one another

Is still a bit of a mystery,

But if that communication method is disturbed,

Well, all bets are off.

Narrator: So what could disrupt communication in a whole flock?

One possible theory could be meteorological events.

[ thunder rumbles ]

Storms could kill birds very quickly.

[ thunder crashes ]

Arkansas is kind of right in the middle of tornado alley.

So they're a hot spot for severe weather.

[ thunder crashes ]

Bradley: One thing's for certain --

They could not withstand a bolt of lightning --

Not a direct hit and not even a proxmial hit.

So any birds within 30 yards

Are probably going to evaporate into a puff of feathers.

Narrator: The birds' bodies were found spread out over a 2-mile area,

Suggesting that a whole flock had been hit.

But could lightning really be powerful enough

To affect thousands of birds in flight?

Generally, where the lightning strikes,

Lightning can emanate out

20, 30, 40, 50 meters from the strike.

So it could affect birds roosting in a tree,

But it would be highly unlikely that it would affect

A flock of birds in flight.

Narrator: If it wasn't lightning,

Could it have been a storm of a different kind?

It could be hail.

A hailstorm could have a devastating effect

On any flock of birds.

When you think of a heavy hailstorm,

What you need to imagine is the sky full of falling hammers,

I mean, potentially fatal for virtually any species,

Even larger birds.

Narrator: In 2018, a duck and a vulture were killed

By hail in a colorado zoo.

Man: I have never been in weather like this before.

This was the damage done to cars in the parking lot.

Dagmar: The world's record for the largest hailstone

Was 8 inches in diameter,

So that's big enough to kill a cow, never mind a blackbird.

Narrator: Although the national weather service

Did record a storm in arkansas on new year's day,

It was already well east of beebe

By the time the birds started falling.

So what else could have caused this mass carnage?

Narrator: New year's day, 2011.

The residents of beebe, arkansas,

Have woken up to find the town covered

In around 5,000 dead birds.

With storms, disease, and toxins ruled out,

What caused the aflockalypse?

When you examine this incident closely,

The date and the time of these deaths is particularly telling.

The fatalities happened on new year's eve.

Narrator: New year's eve -- a prime time for celebrating

That's probably not quite as much fun for animals.

Bradley: Amid all the new year's festivities,

There were numerous fireworks displays.

And fireworks have been known to cause panic

Amongst animals of all sizes,

From domestic pets through to wildlife,

And especially birds.

Dagmar: They fly. They look for an escape from the noise,

From the danger, from the sound, from the light.

And in doing so, they can run into danger

Or possibly run into themselves.

[ fireworks crackling ]

Narrator: But there were fireworks all across the country,

So why did they only affect birds in beebe?

Weeks later, meteorologists discover something interesting.

Dagmar: Radar was showing something called a temperature inversion.

Normally, at night, the atmosphere cools with height.

So you get the warmer layer at the surface,

And with height, the atmosphere cools.

Narrator: On rare occasions, this inverts,

And the air becomes warmer the higher you go.

Dagmar: So you have cooler air at the surface,

And you have warmer air up high.

Narrator: Temperature inversion was very important,

As it can actually alter sound.

Sound travels differently through cool air

Than it does through warm air.

So when it hits that warmer air, it tends to speed up

And bounce back towards the ground.

Bradley: In essence, the temperature inversion

Created a colossal loudspeaker

As large as the heavens themselves.

It amplified the sounds of the fireworks to such a degree

That it panicked the birds from their nests,

Caused them to fly at full speed,

Blindly, in the dark,

Until they collided with each other,

Causing catastrophic trauma injuries.

[ fireworks crackling ]

Narrator: The following year, new year's eve fireworks

Were banned by the police chief in the beebe area,

And it's hoped that the chances

Of another aflockalypse now are low.

[ insects chirping ]

Tuscon, arizona, June 2015.

Some wildlife cameras have been set up in a national park,

And one is about to capture a display

That's as weird as it is amazing.

On first glance, this looks like an animal

At a desert festival wearing a headdress.

You can see that it's furry and stripy,

And it looks like it's got an enormous, great big hairdo.

Narrator: But that's a rear end in the air, proudly on display.

Gillian: This is incredible.

This is a skunk doing a handstand,

Legs splayed and tail in the air.

I mean, when I saw this, I just thought,

"wow. It's so impressive. I mean, what a stunt."

Narrator: This western spotted skunk does a handstand for over 10 seconds.

So the question is, why? What is it doing?

[ insects chirping ]

[ insects chirping ]

Narrator: Tuscon, arizona, and a skunk has been caught on camera

Doing a bizarre handstand for over 10 seconds.

Unless it's been employed by the local circus,

It's not clear why it's learned this acrobatic feat.

Gillian: My first thought was,

"surely it's trying to impress something or someone."

Lucy: Could it be to attract a female?

Well, all sorts of animals have extraordinary displays

In order to attract the opposite sex.

Gillian: Famously, the birds of paradise,

They are elaborate in their colors and their plumage.

But also, they have these incredibly elaborate dances

To impress the females.

And adélie penguins will provide females with pebbles

In order to attract them.

Narrator: Maybe their girlfriends asked for a ring

With a massive rock on it...?

And there are these hooded seals --

They have these huge inflatable noses.

Narrator: Knock 'em dead, fellas.

[ snorts ]

Gillian: And this one is possibly quite a strange one here.

This is a male giraffe drinking the female's urine.

Narrator: Well, that's something you don't see every day.

So is this some strange courtship ritual?

Narrator: It could be like an old-fashioned love story.

Or maybe not.

Lucy: The seduction technique of the skunk

Is relatively straightforward.

Just run in and grab a female you like by the neck,

And that's it.

No prizes for romance.

[ laughing ] I'm sorry.

[ romantic music playing ]

Narrator: If this isn't about mating, could it be an odd skunk ritual

Of trying to scent-mark in an upside-down fashion?

Lucy: Scent is extremely important for lots of animals.

Narrator: Spraying scent is a way

Of communicating an animal's presence to others.

Now, doing a handstand at the same time

Isn't as unusual as you might think.

Gillian: We're very familiar with dogs urinating

And scent-marking on things, but incredibly,

Dogs will also go up on their front paws

To try and pee and urinate as high up as possible.

Narrator: Scent can reveal information

About the sprayer's health and size.

So the higher up the spray is,

The larger an animal might seem to others.

Visitors at edinburgh zoo in scotland

Were about to get a front-row seat

To witness this behavior.

Incredibly, pandas will actually invert, do a handstand,

And urinate up against trees, as well --

Again, to make them appear bigger than they are.

[ laughter ]

Woman: Oh!

However, what we do know about skunks

Is that they won't spray to advertise their size.

Narrator: So they probably don't do handstands to scent-mark.

Now, skunks are famous for smelling unpleasant,

But this odor comes from a special liquid

They occasionally spray.

Gillian: In this footage, the skunk is possibly

Doing what skunks are most famous for,

Which is spraying its very pungent urine.

Narrator: Technically, it's a scent produced in the anal glands.

Gillian: Skunk spray isn't smelly by accident.

It's packed full of sulfurous elements,

Sulfurous chemicals in it.

So they do use the spray like a weapon.

[ barking ]

Narrator: It was hard to see the skunk spray,

So let's watch it again in slow motion.

Gillian: They're very accurate.

They can aim from about 10 feet away.

They go for the face, and if it gets in your eyes,

It can cause irritation, nausea, and even temporary blindness.

[ sneezing ]

Narrator: Skunks only produce enough for around six sprays

Every 10 days.

So they will only release their precious supply if they have to.

Perhaps the dance is a cheaper alternative.

What this skunk is likely to be doing here is a threat,

But a threat of a different kind.

Lucy: He's noticed the camera.

He thinks it's a threat, and so he's doing this warning dance,

And if that doesn't work,

Then he will take on his last resort,

Which is squirting his unpleasant scent at the camera.

[ whimpering ]

Narrator: A number of animals give a warning

Before bringing out the big guns.

Having a fight or using weapons like toxic venom can be costly.

So many animals prefer to threaten first,

In the hope the predator will back down.

So if you ever find yourself standing face-to-tail

With a skunk like this, you've received your warning.

Make your escape from the spray while you still can.

[ insects chirping ]

Dan: July 2018, tallahassee, florida.

There's a frog sticking to the window of a house,

And for whatever reason, the frog is flashing light.

So, why on earth is this frog flashing?

It's like a christmas frog.

[ insects chirping ]

[ insects chirping ]

Narrator: July 2018, tallahassee, florida.

This electric-looking amphibian is discovered on a window.

What is making it flash?

Frogs are amphibians and can live on land and in water.

Some are found in the deepest of rainforests,

Others in people's backyards.

There are lots of different kinds of frogs in the world.

There are, like, 5,000 different kinds.

Lucy: There are frogs that can fly.

There are frogs that can freeze solid.

There are frogs that live in deserts

And can live underground for months on end.

Narrator: So far, we know of no species that flashes like this one.

Could it be a new type that we just haven't seen before?

People are finding new ones all the time.

Just in 2016, there was a new species called mahony's toadlet

That was found in australia.

Narrator: It was one of dozens of new frog species

Discovered in the last few years

And is recognizable by these orange marks on its legs.

But could a brand-new flashing species really turn up

On a residential window?

This is tallahassee, florida.

This is a place that's pretty well surveyed for animals,

And if there were one that glows in the dark,

I think we'd have seen it by now.

Narrator: In that case,

Could another idea illuminate us?

So, has this frog actually swallowed something

That flashes --

Something that we've made, like a torch or a kid's toy?

It looks a little bit like a christmas light inside the frog,

But it's probably not electronics.

Narrator: Frogs aren't going to be tempted by a piece of random plastic.

They go for much more appetizing snacks,

Like this delicious-looking... Worm thing.

It probably ate something natural that lights up,

Like a firefly.

Lucy: Fireflies aren't flies. They are insects.

They're part of the enormous order of beetles.

So fireflies produce this light by combining a chemical

Which we call luciferin with oxygen

In specially evolved organs.

Narrator: So, if the firefly is inside this frog,

How is it we can still see its light?

Dan: Frog skin is incredibly thin.

In fact, frogs can even breathe through their skin.

So the fact that the light shines right through it,

That's not surprising at all.

Lucy: So, the question is,

How is the fly still flashing once it's been eaten?

Dan: I think this firefly is still alive.

I mean, a frog doesn't even chew its food, right?

It just swallows it.

Narrator: There have been other sightings across america

Of flashing frogs,

But fireflies are a big mistake for dinner.

Most in north america are toxic

And have enough poison to kill a lizard.

In fact, their light probably developed as a warning.

Perhaps this frog didn't get the memo.

[ insects chirping ]