Nature's Strangest Mysteries: Solved (2019–…): Season 1, Episode 10 - Crow Crime Scene - full transcript

Narrator: Ever wonder why crows
would gather

Around the body
of a fallen comrade?

Man: This must have been
one popular crow.

Narrator: What's electrifying
the skies over venezuela?

This is the lightning strike
capital of planet earth.

Narrator: And what
could cause a lake shore

To become smothered
in spider webs?

Layers of webs pretty much
covering everything.

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...

The truth behind them
is astonishing.

My god!

Nature's greatest
mysteries, "solved."

Captions paid for by
discovery communications

Narrator: February 14,
2018, seattle, washington...

A seemingly ordinary valentine's
morning erupts into chaos.

A cacophony of squawks
draws schoolteacher

Jean sherrard
to the bizarre scene outside.

Narrator: A huge flock
of crows has gathered.

They all seem to be looking
at one individual.

The question is, "just what is
going on in their bird brains"

To make them do this?"



This is a really strange
bit of behavior,

And all sorts of questions
spring to mind

As to what's actually
going on here.

Why have they gathered round
this crow?

Perhaps these crows
gather round to assess it

And see whether
it's just injured

Or whether there'd be a way of
that crow coming back around.

Narrator: So have these crows gathered
to help out a wounded flock mate?

After all, the social dynamics
of crow society

Show these birds of a feather
really do flock together.

Crows mate for life.

And young crows might remain
with their parents

For 5 or more years,
some of them,

So that you get really large
extended family groups.

Narrator: But there's no room for
being a lazy teenager in a crow family.

Young crows and corvids

Will help their parents
to raise siblings.

Marzluff: And those offspring
will help feed the young,

Defend the territory,
look out for predators.

Narrator: Other animals with
strong social bonds like lions

Have been known to support
their injured friends.

Is this happening here?

Certainly if a mate is injured
in a nonlethal way,

They will still remain together.

They do seem to have
a really strong loyalty.

Crows have been reported to feed
an injured bird

If it couldn't feed itself.

There are even reports
of individual crows

Helping support another bird
who's wounded,

And I can see that definitely
happening with a mated pair.

But it's really unlikely
that they would do that

For unrelated crows.

Narrator: A group of crows
is called a murder.

In seattle, this cackling army
is at least 60 strong.

But crow families have no more
than a dozen members,

So this gathering is unlikely
to be a family affair.

So in this instance,
all these crows

Gathering round to help a crow,
it doesn't seem likely to me.

Narrator: There must be
something else going on

To bring this flock together.

On closer inspection, it seems
our crow is way beyond help.

It's dead.

For a really long time
throughout human history,

We have noticed that crows
seem to respond

Really strongly to their dead.

When a crow dies, a murder
of crows will gather around

That dead crow in
what's known as a crow funeral.

A bird will fly in, and it's...

You know,
as it's going about its day,

And it will see a dead crow
on the ground.

One starts to call,

Others come in,
and they start calling.

It's a cacophony.

Narrator: But what's the motive
for this crow funeral?

Could their interest
in the dead crow

Be an attempt to come to terms
with losing a flock member?

Marzluff: One other reason
they could come in to a funeral

Setting would be to mourn
the loss of that individual.

Swift: Maybe it was
an expression of grief.

One of their neighbors died,
or their mate died,

And they're coming
to pay their respects.

Marzluff: They might actually
be having emotional mourning

Sort of response to that.

Narrator:
In the animal kingdom,

Only a handful of species
like dolphins and elephants

Respond to their dead
in this remarkably human way.

Could crows also be a species
that grieves?

John marzluff is
professor of wildlife science

At the university of washington
and has been working with crows

For decades to better
understand their behavior.

John wants to explore the mental
reactions of wild crows

When a fellow crow dies.

After anesthetizing
his subjects,

He examined
their brains in his lab

Using a special bird-sized
scanning machine.

The way we scan a crow's brain

Is to use
what's called a micro-p.E.T.,

Or positron emission tomography.

Narrator: The p.E.T. Scan will allow
john to see which parts of the crow's

Brain light up
during a crow funeral.

Firstly, to simulate
a crow's reaction to death,

He showed a crow
a stuffed dead bird.

John wanted to measure
their mental reactions

To the dead crow,

But the result wasn't quite
what he'd expected.

I kind of expected them to be
very stereotyped,

In a very simple,
like, response,

But it wasn't like
they were fearful

Or even emotional
about this particular scene.

Instead, what we saw was
that part of their brain

Was activated that is indicative
of complex decision-making.

Narrator: So it seems that the
crows at the funeral are flocking

Together
not to pay their respects

But to assess the situation
and make decisions,

In which case, "what answers
are these brainy birds seeking?"

Maybe they're turning detective

And investigating
the crime scene.

Perhaps it's a kind of a novel
predator like a unique dog

Or a human
that they need to learn about.

Narrator: To test the theory,
john added a suspect to the crime scene,

A human holding the dead bird.

Swift: Well, they have made
this connection

That this person
holding a dead crow

Must have had something to do
with their death,

Or in some way they're bad.

Narrator:
Adding this new threat element

Activated a different part
of the crow's brain.

We saw the hippocampus
activated,

And the hippocampus is
an important part of the brain

That is used to form important
social and spatial memories.

That indicates that these birds
are forming a memory.

Narrator: John's results suggested
that wild birds will commit

These crime scenes to memory,

But just what exactly
are these super smart birds

Trying to remember?

Narrator: February 14, 2018,
seattle, washington...

A crow funeral
is filmed on a suburban street.

What are they doing?

To find out,

Scientist john marzluff
has been examining crows

To see how they react
to their dead,

And he's discovered that

They seem to be
trying to memorize the event.

Crows appear to be really good
at learning from crime scenes,

And the two things that we know
that they learn,

And there might be other things,

Is the location
of the crime scene itself

And any suspects
that were present

At the scene of the crime.

Narrator: So is our valentine's
day crow funeral in seattle

Really just one
big crow investigation.

If so, it could be beneficial
for every bird in the flock.

By gathering around the dead
or dying crow,

What the others are doing
are gleaning information,

Learning and finding out
what caused the accident,

What caused their death,

And once they've got
that information,

It helps them avoid
a similar end themselves.

So make sure that they don't
meet the same fate

As this bird
that has just recently died.

Marzluff: It pays to be smart
and learn things as you go

Because you might be able to use
that information in the future.

Narrator: So it's not so much
a crow funeral.

It's more like a crow classroom
where the birds learn

How to keep themselves
safe down the line.

Oh, and by the way,
no need to worry

About the welfare of the crows
john used in his tests.

We wake the bird up, and then
it can be released to the wild

And go about its own life.

♪

Narrator: October 2018,
lake vistonida, greece...

Residents living on the
lakeshores wake up

To a very strange sight.

Oh, no.
Oh, no. Oh, no.

Narrator: Almost overnight,
their beach has been transformed

Into an arachnophobe's
nightmare.

This is a creepy one.

This place in greece
all of a sudden

Is totally covered
in spider webs.

Layers of webs covering plants,

Pretty much covering everything
and over a huge area.

It looks like Halloween
decorations, but it's not.

It's totally real.

Narrator: The super web spans
almost 1,000 meters.

What could be going on
in the spider world

To make them spin
such a gigantic structure?

Could this be the work
of a group

Of unusually social spiders?

Spiders certainly aren't known
for their teamwork.

Everybody thinks of spiders
as these solo hunters,

But there are a few kinds
of spiders that act communally,

Almost like an anthill,

Where a whole bunch of spiders
will share a great big web,

And that could be
what's happening in greece.

Narrator: Of the almost 50,000
species of spider worldwide,

Only 23 species
are truly social.

Cooperative spiders
create immense webs,

Home to up to
50,000 individuals.

So do we have a fast-growing
community

Of social spiders
here in greece?

They are a species
of orb weaver,

Which typically aren't social.

There aren't any
communal spiders in greece

Or anywhere near greece.

That's not going to
explain this.

Narrator: If there are no
social spiders in greece,

Did these long-jawed orb
weavers migrate here?

Spiders crawl slowly
through their webs,

And they crawl on the ground.

Narrator: But surely they
haven't swum across the lake?

What a lot of people
don't realize is

That they can also fly.

Narrator: October 2018,
lake vistonida, greece...

The shoreline looks
like a Halloween party.

Spider webs are everywhere,
so how did they get here?

Could an army of spiders
have flown in overnight?

A spider's version
of an airplane

Is just a really
long strand of web

That gets caught by the wind,

And if the spider is holding
on to its strand

And moves with it,
it's called ballooning.

They will climb to the top
of whatever

Is most prominent
in their environment,

So a top of a tree,
blade of grass.

They will stand on their
tiptoes, raise their abdomen,

Let out silk,
and then float away.

♪

So they travel huge distances
without any wings,

Just using these silk lines.

Narrator: But only some
spider species can balloon,

And it seems unlikely
that so many ballooning spiders

Would happen to land in this
one spot, as once airborne,

They have little control
over where they go.

So could the greek lake
have been their launch site?

Maybe all those long strands
of web have accumulated

And made these big huge webs
that cover everything.

Narrator: When thousands
of spiders balloon,

The tangle of silk threads
they leave behind

Can be surprisingly
lovely to look at,

But why would a bunch
of long-jawed orb weaver spiders

Be ballooning
in such large numbers?

Well, baby spiders

Have an especially
big motivation to move.

Sixty-five babies can hatch
from just one egg sac.

And these are all
in a very small space,

So there's a lot of competition
and potentially predation

Happening from their brothers
and sisters

As spiders are cannibalistic.

They will eat each other,

So obviously it's a good idea
to disperse

And get far away
from any brothers and sisters

That might want to eat them.

Narrator: No wonder young spiders
will go to extreme lengths

To find a new home,

But was it a bunch
of baby spiders

Ballooning off to pastures new
that carpeted the lakeshore?

If they were ballooning,
you would expect to find

Just individual strands
everywhere,

And these are well-built webs.

Narrator:
If they're not ballooning in,

Could the solution be something
to do with weather?

This shoreline in greece had
warm and humid conditions,

Which is perfect
for an abundance of mosquitoes.

Narrator: Millions of mozzies cued
a frenzy of feeding and mating.

So the reason there were so many
spiders in greece all at once

Is because all of a sudden,

There was a ton
of food for them.

With that much food available,
the spiders went to town.

Narrator:
This glut of food and ideal

Weather led
to a breeding bonanza,

And an explosion
in the local spider population.

And that's what resulted in this
huge, huge

Extraordinary webbing
that you saw there.

And so it turns into the
new york city of spider webs.

Narrator: Perfect weather
and lots of spider food

Means lots of spiders,
and that means lots of webs.

Greek spider town mystery...

Solved.

Astronauts at the international
space station

Capture a dramatic storm
over south america.

One lake in venezuela
is particularly electric,

Which begs the question,
"why?"

Lightning is a very common
occurrence around the globe.

There are around 100 lightning
strikes per second.

That averages out to around
3 billion

Lightning strikes per year.

Narrator: 3 billion strikes...
that's a lot of electricity,

And some places are much
more hit-prone than others.

Riskin: People love to say
that lightning

Never strikes twice
in the same place,

But they obviously
haven't visited

Lake maracaibo in venezuela.

This place is out of control.

[ Thunder rumbling ]

Narrator: With an average of 28
strikes a minute

On 300 nights every year,

This place holds the world
record for lightning activity.

This is the lightning strike
capital of planet earth.

Narrator: The question is,
"what makes this place so electrifying?"

Narrator: What is causing
lake maracaibo in venezuela

To be the lightning capital
of planet earth?

One possibility is that humans
have done something there

That has caused all
this lightning to show up.

It sounds impossible,
but people can totally influence

Where lightning strikes.

Lightning is always trying
to find the quickest path

To the ground,
the shortest route possible.

Narrator: And in big cities,
that shortest route

Usually starts
with the highest skyscraper.

Are man-made structures
attracting lightning

To this lake?

It's very unlikely
that there would be

Any kind of human element
involved

In terms of a building,
of a city.

Riskin: You don't have
skyscrapers all around this lake.

It's just a few small buildings.

They're not
empire state buildings,

So they're probably not big
enough to focus the lightning,

And the lightning
is not happening there.

It's happening out
over the lake.

Narrator: This might be the most
electrifying place on earth,

But it's teeming with life.

Jaguars roam the lush banks,
and the lake,

Which is three times
the size of rhode island,

Is home to freshwater dolphins
and over 100 species of fish.

♪

So what could be causing
this region's

Tremendous thunderstorms?

Perhaps something
more industrial.

Midcap:
One of the original theories

Was that it could possibly be
driven by or fed by methane.

So the lightning storm
is happening way off the ground,

Like 50,000 feet up,
and the methane,

If it's coming
out of the ground,

Would have to travel
a long distance to get there.

Now, anybody who has ever
farted knows

That it's going to dissipate
pretty quickly,

And to be honest, it would
look like a giant fireball,

Not a whole bunch
of lightning strikes.

Lightning really doesn't depend
on methane

In any way to feed itself
or intensify strikes,

So methane has been ruled out.

Narrator: It's not buildings,
and it's not gas from the oil industry.

Looks like humanity's
off the hook.

Could something natural
be responsible

For lighting up the skies
above venezuela?

♪

So this is a very fascinating
event in that

There are a number
of things going on here.

First and foremost would be
the geography of the region,

So lake maracaibo is
surrounded on three sides.

It's hemmed in to the east,
to the west,

And to the south
by very high mountains.

To the north, lake maracaibo
opens up to the caribbean sea.

So you get all this warm air
that comes from the caribbean.

Midcap: It's warm air.

It's moist air, and it creeps
into the lake maracaibo region.

That air has to go someplace,

But when it enters
the lake itself, it realizes,

"okay, there are mountains here.
There are mountains there."

There are mountains.
Where am I going to go?

"I can't go to the side.
I have to go up."

And then you get this cold air
down from the andes,

And it mixes
and causes a thunderstorm,

But the thunderstorm
can't leave.

It's stuck there
and just gets amplified.

And this happens night after
night after night after night.

Narrator: So the towering mountains
are trapping powerful storms,

And with nowhere for them to go,
every evening is explosive.

♪