Aerial Assassins Deadly 360

This is... Deadly 360.

We pit three of the deadliest predators against their prey.

Examining their hunting strategies and escape tactics from every angle.

By delving beneath the fur and the feathers,

we find out why a hunt succeeds...

and why they sometimes fail.

One thing's certain, prey animals are anything but sitting ducks.

Their defensive strategies keep them alive.

And push predators to the limits.

Prepare for Deadly 360.

This is Deadly 360 Mission Control.

Where all of today's action and analysis takes place.

We have access to some of the most enthralling hunts

ever caught on camera.

I've recreated three of the most exciting

and analysed them from a variety of different angles and perspectives

in true 360-degree style.

The predators we're looking at have to find and catch food,

or they just won't make it.

In the wild world, simply managing to survive

is the greatest challenge of all.

I present to you the Aerial Assassins.

In today's line-up, we check out

one of the fastest flying insects on the planet.

The emperor dragonfly. An insect-chomping speedster.

We also meet the Daubenton's bat.

A nocturnal hunter who can detect prey in pitch black.

And we'll check out how the kestrel uses its rock-steady vision

to try and catch its prey.

Three aerial assassins,

three very different hunting strategies, all deadly.

They look invincible, but there's a continual race going on in nature

which ensures prey animals are always evolving

spectacular ways of taking care of themselves.

Trying to avoid their fluttering foes - the damselfly.

Agile in flight, and an aerial acrobat.

And this furry fellow, the field vole.

An expert in staying hidden with a burst of speed to outrun its enemy.

And the yellow underwing moth

with its aeronautical tactics, which have to be seen to be believed.

Three prey with three very different,

but effective escape strategies.

So, I've introduced you to all of our contenders,

now it's time to meet our first deadly duo going head-to-head.

This is the emperor dragonfly.

The largest European dragonfly, and with a top speed of 35mph,

one of the fastest insects in the world.

And up against it is this -

his smaller cousin, the damselfly.

But which animal has the edge in the race for life?

It's time to go Deadly 360.

We witness the final stages of the hunt.

The emperor dragonfly is lining up on the damselfly

and chasing it down at top speed.

But the damselfly has great vision and has spotted his attacker.

It's twisting and turning, trying to escape,

but the dragonfly is gaining.

But even in a hunt like this, there are still lots of factors in play.

And to find out why a predator might succeed or fail,

we need to wind back the action

and build up the entire hunt right from the beginning.

This battle takes place in southern France.

And more specifically, on a stretch of river here,

beside the vast grounds of a castle.

Quite fitting for an emperor.

Water is absolutely critical for the dragonfly.

As where there's water, there are many insects to feast on.

And one of the largest potential meals here is the damsel fly.

But they're also the most difficult to catch.

So, that's the arena for our gladiatorial contest.

What weapons and defences do the two animals doing battle have?

Well, the emperor dragonfly's chief ability

is flying at incredible speeds of over 35mph.

But they also have extraordinary vision.

And chomping jaws to despatch their prey in seconds.

All of this makes our predator a pretty scary prospect.

What does our prey animal have to counter?

Damselflies are also hunters,

so have similar weapons to the dragonfly.

But today, they'll need those weapons for defence.

Their vision enables them to see nearly 360 degrees.

They can also hit some superfast speeds through the air themselves,

and they're nimble, able to twist and turn their way out of danger.

With two such talented animals,

this hunt is going to be a close-run thing. Let's see what happens.

The sun has only just come up and it's cold,

so the first thing the emperor dragonfly does is sunbathe,

while shivering its flight muscles.

It needs to warm these muscles up before it can take off.

The damselflies are smaller than the dragonfly

and can warm up their flight muscles faster,

therefore get going earlier.

That gives them a real headstart over the dragonfly.

So let's catch up with what they're up to.

It's the damselfly breeding season. This male tries to impress his girl.

But there are others trying to get her attention. Time for a battle.

But a gentlemanly one, involving synchronised ballet.

The most agile flier has the best flight muscles.

Something the female wants to pass on to her offspring

to give them the best chance of survival.

This battle may look like a simple bit of flying,

but it's extremely tiring work and requires his undivided attention.

Our emperor dragonfly is nearly at optimum temperature.

He's warming up his flight muscles and almost ready to fly.

And when he does, he'll have a whole host of weapons at his disposal.

Let's check them out here in Deadly HQ.

So, this is an emperor dragonfly.

It's the largest species of dragonfly found in Europe,

one of the largest in the world, and it really is packed with weapons.

At the front, you can see the mouth parts are actually quite complex.

It has different plates for munching, crushing and mashing.

And these legs, covered with hairs,

are perfect for catching prey on the wing.

The hairs actually serve as extra grip.

This section here is called the thorax.

You can see it's very large.

That's because it houses the wing muscles, which power its flight.

Those muscles make up two thirds of its bodyweight,

which is just extraordinary and shows how important

powered flight is to the dragonfly.

So let's see all of these in full effect.

The emperor's flight muscles are warmed up. Time for takeoff.

And the first thing it needs to do

is get high up into the air using those large flight muscles

in order to scour its patch for potential meals.

Not good news for the damselfly, who's burning up valuable energy

and tiring out its flight muscles trying to impress the female.

This distraction means he's unaware the dragonfly is hunting him down

using its incredible vision.

Check out those eyes.

They are some of the most impressive found in the whole natural world.

They cover pretty much the entire head.

And each compound eye has about 28,000 lenses.

It means they can see their prey from as much as 15 metres away.

Which might not sound like much,

but if you scale it up to my size,

it would mean I could spot a pizza from 350 metres away.

Which I like the sound of!

But unlike a pizza, the damselfly is no easy meal.

With its four wings,

it can weave through the air at incredible speeds.

But the dragonfly has the manoeuvrability of a helicopter

and speed of a jetfighter.

He can fly forwards, backwards, even hover on the spot.

Let me show you how he does it.

OK, let's get a closer look at those wings.

So, at the base of each one is a flexible pivot,

which means each wing can be moved independently.

Secondly, they can drive those wings in a figure-of-eight shape,

which allows them to hover in one spot.

And thirdly, at the end of each wing

is a weight called a pterostigma.

This counterbalances the wings and drives them with more momentum,

allowing them to fly at a faster cruising speed.

So they're very well equipped

to deal with their smaller damselfly cousin.

But damselflies are put together in a fairly similar way.

Let's find out how.

Dragonflies and damselflies are very closely related

and have a similar bodyplan, but there are subtle differences.

If you look at the head of the damselfly,

you can see it's proportionally smaller than that of the dragonfly.

And more of the eyes are exposed.

This gives it a broader field of vision,

so it's equally good at zoning in on its prey,

but it's also very, very good at looking behind it

at things that might be attacking.

Things like its relative, the dragonfly.

The damselfly, distracted by his courtship dance,

has only just spotted the dragonfly,

so starts his bid for freedom immediately.

The dragonfly spots the flickering wings

and switches into full-hunt mode, diving down to hit top speed.

But the damselfly twists out of the dragonfly's path.

The emperor quickly turns back on track.

Exhausted from all the showing off,

the damselfly is beginning to tire.

The dragonfly's gaining and...

..grabs a hold with those hairy legs!

The dragonfly takes a perch and gets stuck in

with its mighty mouth parts.

They can slice horizontally and vertically

and it gets stuck into the flight muscles first

because it knows these are the most nutritious.

In the warmer months, dragonflies are a common sight around us

and it's easy to underestimate these animals.

That's a mistake.

Dragonflies are one of the most complete aerial assassins.

The damselfly displays its acrobatic flying,

powerful flight muscles and excellent vision.

But got distracted by a female.

The large emperor dragonfly with its massive flight muscles,

faster acrobatic wings and munching jaws demonstrated the perfect hunt.

Now onto our next pair of hunters locked in a battle for survival.

This predator twists and turns through the forest in the night.

It's the daubenton's bat.

Up against it is this,

the yellow underwing moth.

Which has the edge in the race for life. It's time to go Deadly 360.

We join the action just before the critical moment

the bat is speeding through the trees in pursuit of its meal.

The moth is also trying to evade capture.

The yellow underwing moth is flapping all his might

but at a fraction of the size of the moth,

its fate seems inevitable.

There is a lot more to a hunt than just the final strike.

What about the hidden factors that'll influence

what happens in the next few seconds?

To find out, we have to wind back to the start and dissect the action.

We're heading to the UK to a piece of woodland in the countryside.

The forest near a water source near this river

are where the daubenton's bat lives

as there are holes in trees and buildings to roost in.

The trees and plants provide the food required

for the bats' favourite meal, moths, which are plentiful.

Which is just as well as a daubenton's bat

can eat 60% of its body weight in just one hour.

What special weapons has the bat got to help it catch a meal?

First up, sharp claws at the end of its legs

and a mouth crammed with 38 needle-like teeth

make short work of any prey.

And they have a super power.

They can use sound to see at night but I'll explain that later.

All of that makes our predator a pretty scary prospect.

But what does our prey have to counter?

That stocky body is packed with flight muscles to help it escape.

They have hearing that is far more sensitive than our own.

They are dazzling in flight. Able to keep any predator on their toes.

So, well-equipped for evading capture.

Right, back to the hunt.

The bat's busy searching for food,

but nocturnal bats have poor eyesight,

so, how can it hunt at night?

Well, it relies on hearing to locate its prey.

Using something called echolocation. Here's how it works.

As the bat's flying, it's emitting a series of ultrasonic clicks.

These are too high for a human ear to hear,

but they bounce back off all the objects in front of the bat.

It could be a tree, it could be potential prey.

The clicks then travel back to the bat

and are channelled down into the inner ear.

The change in vibrations and frequency allows the bat

to build up a three-dimensional picture of the world around it,

and also to zone in on potential prey.

The bat is flying towards the moth,

avoiding the many trees and other obstacles in its way

using echolocation.

It twists and turns, reacting in a split-second

to the information it receives.

The hope is that despite the moth's excellent flying skills,

the bat's reactions will mean the moth gets munched.

We're lucky enough to have an exquisite horseshoe bat skeleton.

It's 100 years old and very fragile, so I won't touch it,

but you don't need to to see what makes it so incredible.

Bats are the only truly flying mammals.

So they're distantly related to ourselves.

We probably shared a common ancestor maybe 18-million years ago.

When you go beneath the fur and the flesh,

it's remarkable how similar their skeleton is to our own.

The bones are in different proportions,

but we've got feet, legs, a pelvis, a complete ribcage,

a skull full of viciously-sharp teeth

for chomping through exoskeletons of insects, and this here.

This is the most remarkable bit for me - the wings.

This is essentially an arm and a hand.

We've got the radius and the ulna, which are the forearm bones,

a wrist, and these are fingers.

The wing membrane that goes between those is just a flap of skin.

But it's so efficient that it's enabled this animal

to become really the second-best flier in the world after the birds.

Let's see one in action.

With the bat speeding towards its meal,

we reveal another essential adaptation of its ear.

OK, so it's pretty incredible that these animals can build up

a picture of their world using ultrasonic echoes,

but it gets even more mind-blowing. Check this out.

Right, because those ultrasonic clicks are so intense,

they could shatter the inner-ear bones.

10 milliseconds before it calls, it disengages them from the eardrum,

going temporarily deaf.

It re-engages them again in order to take in the vital information

as the ultrasonic clicks come back to it.

That is just crazy!

The bat has picked up the moth's location and heads straight for it.

But the yellow underwing has a counterattack.

A simple ear on its body tuned to the bat's ultrasonic clicks.

This gives it a head start as it races for cover.

Mind you, in a flat race,

there is no way they're going to outpace the bat.

What they need to do is outmanoeuvre it.

If it's a hot day and you fan yourself down with your hand,

what you're effectively doing is creating a localised wind.

And that is what happens when a bat flies.

Its wings create a change in air pressure,

which the moth can detect.

Its body is covered in tiny hairs,

and those minute changes in air pressure and wind direction

are picked up by the hairs

and it's enough for the moth to sense where the bat's coming from.

Now, let's see how this drama plays out.

The bat has locked onto the moth,

which is desperately trying to find cover.

As the bat gets closer, it sends faster, high-pitched clicks,

focussing on the moth's precise location.

It's in striking distance and swings those deadly feet forward,

but...it's missed it!

Oh! That's got to be worth another watch.

You can see the bat really thinks it's got its prey.

It swings the feet forward, ready to catch it and...misses!

The moth simply drops out of the sky.

There's various things going on.

First of all, those tiny hairs

have picked up the change in air pressure as the bat gets close.

And also, that ear has heard the change in frequency

of the bat's ultrasonic cores.

When that happens, the flight muscles of the moth

simply go into spasm. They seize up and the moth drops out of the sky.

It's a fairly extreme reaction, but it's kept the moth alive.

This time at least, the moth outwitted the bat,

which is an extraordinary outcome.

But this is only one of hundreds of hunts that will take place tonight.

I don't think this bat will go back to its roost hungry.

The Daubenton's bat is a faster flier,

with echolocation and clawed feet for catching moths.

But the yellow underwing moth's tiny hairs,

hearing and fast-reacting flight muscles saved its life.

This is our last Deadly duo locked in a battle for life or death.

This is the common kestrel.

A small, but perfectly formed bird of prey.

And up against it is this - the speedy field vole.

Which has the edge in the race for life?

This is Deadly 360.

We join the action just before the critical moment of impact.

The kestrel is hovering 15 metres above its target.

The vole is busy feeding on grass

and its brown fur gives it excellent camouflage.

But the kestrel has spotted movement

and is dropping out of the sky towards its target.

It looks like the vole's days are numbered.

Well, not for sure.

As you've probably gathered,

things don't really work that easily on Deadly 360.

So, let's rewind the action and see how things really unfold.

The hunt takes place here, in the United Kingdom.

And more specifically, here, on the verge of a busy motorway.

Motorway verges and surrounding farmland

make the perfect home for the field vole. Food is plentiful,

but grass is low in energy. The vole has to constantly forage for food,

despite dangers from above.

So, we've set the scene.

But how do these animals operate in this environment?

What attributes do they have, in particular,

that might tip the balance in their favour?

Let's have a look at some of the kestrel's killer weapons.

The talons.

They have minute bumps on the undersurface to help grasp prey.

The beak. Perfect for tearing through the flesh

of anything unlucky enough to end up as lunch.

And there's its eyesight.

But more on that later.

So, with all that to help it hunt,

you'd think that our predator would have no trouble making a kill.

But our prey also has some special means of defence.

It's sound, rather than sight, that the vole uses as a key defence.

In this dark, covered world, they need acute hearing to sense danger.

But the key to voles' survival is knowing which way to run

through its maze of tunnels.

And it does that by following its sensitive nose.

If it senses danger, it can shift at high speed,

covering over three metres in just a second.

Scaled up, that's like me running at over 120mph.

Right, back to the hunt.

The kestrel is out looking for food.

Using that fixed glare and extremely keen eyesight,

any prey should keep well hidden

because those eyes can spot tiny movements. Here's how they work.

There are several differences in a bird of prey's eyes.

We have just one focal point and see clearly what's in front of us.

Everything else is blurred.

A bird of prey has two focal points, so can have sharp focus

on absolutely anything inside their field of vision.

To scour a sufficient area for a potential meal using its sight,

the kestrel climbs high above the ground.

The higher it climbs, the more area it can scan.

Once it sees telltale movement, it turns into the wind.

But surely it must be harder to fly into the wind?

The kestrel's doing this deliberately.

It's turned into the headwind to generate lift.

Now it can use the fluttering movements of the wings and the tail

to make micro adjustments so the head can stay perfectly still.

In fact, it'll move no more than half a centimetre in any direction

and stay fixated on the ground.

So, this is a kestrel in the flesh.

It's a male and I guess the first thing you notice

is just how surprisingly small he is.

He's got the classic falcon shape.

The long, thin tail,

these wings are swept back and very pointy-ended.

Can you just see those out wide?

That's a little bit like the motion you might see as he's hovering.

If I can get him to settle down... and focus on my finger...

Look over here.

..then shift the body very slightly, you can see

the head stays in exactly the same place,

just like it does when he's hovering. Can you see that?

That's extraordinary.

Look how lightweight this bird is.

He's easily held on my little finger.

This is an animal that has to kill using precision.

It's not like a golden eagle that can use force, power and weight,

he has to be unbelievably accurate when he's catching his prey.

Once he has, he has a very special extra weapon, which is in the beak.

You can see a little notch there.

You come back from the hooked point of the beak there

and you can just see that notch,

which is actually used to dispatch its prey

by biting clean through the back of the neck.

And it can kill them almost instantaneously.

He is a swift assassin. Let's see all of that in action.

The kestrel's hovering, searching for the vole,

which is busy feeding on low-energy grass above ground.

So, surely, it's in danger.

Fortunately, most of its runways are covered by vegetation,

keeping it safe from beady eyes above.

But it's just broken cover.

The kestrel has spotted movement.

Launching an attack from this height

would give the vole too long to escape.

So, it drops down to about 15 metres to fine-tune the attack.

The perfect balance between field of vision and time to reach the vole.

But the vole never hangs around in open space for long,

and disappears into its maze of pathways.

While the kestrel resets,

let's take a closer look at how the vole knows which paths to follow.

As they move, they leave scent trails of urine.

These serve as a warning to other voles to stay away.

But they also function to provide that vole

with its own scented signpost

of a direction of how it can move around inside its own territory.

So in the presence of a predator,

it knows exactly which escape route to take.

With this as a defence, how will our kestrel manage to locate the vole?

The kestrel knows there's food in this general area,

but the vole has moved undercover and it's too hard to pinpoint.

But the kestrel has one final weapon to help hunt down its prey.

The smelly trails that the vole leaves behind could be its undoing.

There are chemicals inside its wee

which will glow under ultraviolet light.

Humans can't see into the ultraviolet spectrum,

but if we could, there would be a faint glow

which would look a little bit like this.

Not so invisible now, is it? And guess what?

The kestrel can see into ultraviolet light.

When it's seen from overhead, it must look like this.

All of the tracks and trails made by the vole are clearly visible.

And the kestrel can zone in on them and go straight to its prey.

It swoops down to take a closer look.

Far from the safety of its burrow,

the vole's defence strategy is to sit still,

hoping the kestrel will move on.

But nothing escapes the kestrel's ever-vigilant gaze.

Sensing the impending danger,

the vole now uses a burst of speed to try and outrun the kestrel.

But its reactions are too late. Let's see that again in slow-motion.

We can see the kestrel's wings fold in,

allowing the bird to drop down on a perfect trajectory towards its prey.

At the last second, the talons open up and punch into that vole.

Once they're in, they are definitely not coming out.

Now he finishes it off with his beak and starts feeding.

The kestrel's hovering method of hunting

might seem like an awful lot of effort to go to,

but scientists reckon it's 10-15 times more effective

than if it was to launch its attack

from an elevated position, like a branch or a telegraph pole.

Using this method, it's successful in one out of three hunts,

which are pretty good odds.

The vole has superb hearing,

a sensitive nose to follow smelly tracks and it's pretty speedy.

But it was outdone by the kestrel's deadly talons, hovering skills

and eyesight that meant it could zone in to land a winning blow.

Usually on Deadly 360,

we concentrate on one family of animals.

But this time, we looked at a bat, a bird and an insect.

They could not have been more different.

Bt what they have in common is that they all use

the power of flight to Deadly advantage.

That's all we've got time for.

Join us next time as three more pairs of animals go head-to-head

and we analyse the action Deadly 360 style.

Subtitles by Red Bee Media Ltd

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