Rivers Wild UK

The UK is wilder than you may think.

Just 3% of this land has been built upon

and so there are plenty of world-class wild spaces -

and incredible wildlife.

I'm Colin Stafford-Johnson.

And I'm Lucy Cooke.

And every day we're going to be discovering the top wilderness spots

in the UK and revealing just how wild our islands are.

We'll be travelling from rivers to mountains,

from forests to seas and even to some of our wildest cities,

celebrating the incredible range of wildlife that lives and thrives

amongst our precious wild places.

We'll also be going behind the scenes with Steve Backshall

and the Wild Alaska Live team,

covering all the wildlife action triggered by the annual arrival

of millions of Pacific salmon to this vast wilderness.

As a wildlife cameraman,

I've been fortunate enough to have travelled the world,

but the wild landscapes and wildlife of these islands

have a special place in my heart,

and are full of the most inspirational wildlife stories.

And I've been passionate about protecting wildlife all my life,

so I'm going to be joining the conservation front line

here in the UK to learn about how we keep our wildernesses wild

and allow our wildlife to thrive.

This is your daily dose of the very best the UK has to offer.

This is Wild UK.

The UK has a wealth of wild places to choose from,

but we're kicking off today with a look at the rich world

of rivers and waterways.

You can really sense the raw power of water in places like this.

It's actually scoured out the very hole we're standing in over time

but, at the same time,

it adds almost a sort of hypnotic, benign quality to it.

And, of course, they're such a crucial lifeline

for a wide range of wildlife.

This is the River Orchy in Scotland,

and you might be lucky to spot otters or kingfishers or salmon here

and that's true of waterways all across the country.

Later, I'll be finding out how important the River Wye is

for wild salmon returning to the UK to breed.

What always amazes me is the fact that they have such energy left

at the end of their long journey.

We'll also be joined by some familiar faces

sharing their best past experiences of the wildlife

that relies on our rivers and waterways

and the conservation success stories that have helped them.

Oh! I can see it, I can see it, it's there!

That is incredible!

And I'll be discovering the wild side of Britain's canals.

Oh!

How fantastic!

I LOVE kingfishers.

But, first up, time for a snapshot of our rivers and waterways

right across the UK in 2017.

The River Severn is the UK's largest river,

snaking its way almost 220 miles - 352km -

from its source in the Welsh hills.

In its lower reaches,

it has one of the world's largest tidal ranges at 15m,

creating the spectacular Severn bore.

Where our major rivers empty into the sea,

amazing wild estuaries are created.

The UK has over 90 estuaries and is home to over a quarter

of all the estuaries in north-west Europe.

Morecambe Bay forms at the mouth of five rivers,

covering a staggering 310 square kilometres, 192 square miles.

Estuary mud teems with life and is a vital resource

for our native and wintering birds.

During the winter, over a third of a million birds

can be present in the Wash.

Almost all of the world's 200 chalk rivers are found in the UK.

Rivers like the Itchen and Avon,

which are home to some of our most iconic wildlife

and are rich in invertebrate life.

As these rivers make their way to the sea, they create

some of the most picturesque British countryside landscapes

and are believed to be the birthplace of fly fishing.

Now, the UK has such a wealth of rivers and waterways,

we'd like you to share your images and stories with us

using social media and the hashtag #MyWilderness.

I'm constantly amazed at the quality of photographs

that people are getting these days with their smartphones.

But if you want to get something a little bit fancier

and you're by a river, think about shutter speed.

If you use a really fast one,

you can sort of capture the sharpness of the water

at a moment in time, but if you use a slow one,

then you can get that almost ghostly, ethereal,

flowing quality of water.

This river is especially photogenic, but actually all rivers are, really,

and I think one of my favourites to take photos of is the River Wye,

because you get such a variety of landscapes.

It meanders its way through Wales and England

and, of course, as an added bonus,

it's one of the best places south of Scotland

to spot a very special animal.

The River Wye winds through the Welsh and English countryside.

And, thanks to its unspoiled rural location,

its wild waters are a haven for wildlife.

There's always something to see when you hang out on the river bank.

They just seem to attract life.

Kingfishers, water voles, dragonflies and otters

all call the Wye home.

But the animal that the River Wye is most famous for

is the Atlantic salmon.

Now, it's also known as the king of fish and there's a good reason why.

Adult salmon are big fish and amazing athletes.

After years spent at sea,

feeding off the coasts of Norway and Greenland,

they travel thousands of miles back to the UK,

to the very river in which they grew up,

using their in-built map and compass.

Their spawning grounds on the River Wye are 130 miles -

208km - inland, but they don't make that journey all in one go.

This section of the river is about 90 miles from the sea

and you'll often find that salmon will take a break

and rest up in deep pools just like this one.

The salmon wait here until the time is right

for the final leg of their journey.

I wanted to follow the route the salmon will take

in a few months' time, when autumn comes and rain swells the Wye.

That's when they can make their final sprint,

climbing over 300m into the Welsh mountains.

It's hard to imagine how they manage to overcome rapids like these.

They can leap well higher than me.

What always amazes me is the fact that they have such energy left

at the end of their long journey.

They won't have eaten for the entire time they've spent on this river.

They're doing all this on an empty stomach.

It's extraordinary what they can achieve

when you think they're using their very last reserves of energy.

It's an incredible feat and not all of the salmon make it.

I'm now in the very upper stretches of the River Wye,

in one of the many little tributaries

that feeds into the main channel itself,

and this is where the salmon come to complete their journey.

It's here they will spawn the next generation of fantastic swimmers.

The resulting numbers of baby salmon in the Wye

are an indication of the health of the river.

So I'm joining Stephen Marsh-Smith and Haydn Probert

from the Wye and Usk Foundation.

They're using the latest technology to catch and count young salmon.

An electric current briefly stuns the fish

so they can be caught without harming them.

Electrocuting fish, it sounds pretty dramatic,

but they recover very quickly, don't they?

Yeah, as soon as they're out of the current, the fish will be fine.

The smaller fish recover a lot quicker.

Ooh. Is that one?

-Yeah.

-Nice.

Oh!

There we go. Ooh, three of them.

So how old would these guys be?

Just a couple of months.

-Is that all?

-Yeah.

-Wow!

And so, basically, these surveys are going to tell you

how the population of young salmon are doing over time,

and how are they doing?

Well, rather better than they were when we started,

I'm very pleased to say.

And why is that?

Why are there more here now than there were a few years ago?

Well, in this part of the river, we've sorted out acid rain,

or the effects of it, adding limestone sand

to all the little tributaries that run into it.

And that's brought back the invertebrate life,

and it's brought back the fish life, including the salmon.

So that's the timer.

Turn that off.

And see what we've got.

Not a bad little haul, is it?

Very nice.

The team records the survey results.

And very soon the young fish are free again

to enjoy the clean waters of the River Wye.

Nice to see these little guys

back in the river again where they belong.

You know, in the next year or two,

a little switch is going to go off in their brains

that's going to tell them to swim downstream to the sea.

But the fact that these animals can get from here

and all the way down the river and out to Greenland and back again

is somehow very reassuring that Britain is still wild.

The journey taken by those little salmon parr really is astonishing.

It always amazes me how they make their way out of the river

to the feeding grounds and get back to the river of their birth.

But at least people are here improving the water quality

and things are looking good for them,

and that's important because the River Wye salmon

are actually a unique population.

So there are different populations in each river all around the UK?

Exactly.

Yeah, and you might think you have to go to really remote places

in order to see the salmon leaping up waterfalls

but actually you don't.

On the River Severn in Shrewsbury,

the man-made weir is a great place to see them leaping,

and it's proving to be quite an attraction.

Salmon are a big draw for wildlife watchers,

anglers and photographers right here in the UK.

But they're also the reason for all that activity in Alaska right now.

The return of the Pacific salmon heralds a real wildlife spectacle

and, when that happens, you can be assured that wildlife film crews

are not far behind.

The salmon also attract large predators like the salmon shark.

And this was an opportunity for Wild Alaska Live's Steve Backshall

to get close to a shark he's never seen before.

But just how did Steve and the team set about their challenge?

This is going to be home for the next six days or so.

We're surrounded by the chilly waters of Prince William Sound.

There's always something going on out here -

loads of sea otters, seals and sea lions.

So, yeah, it's a really exciting place to be.

Steve and the crew are eager to get going

whilst the weather is on their side.

So they load the gear into the boat and head out to find the sharks.

They're looking for a telltale sign of the shark's dorsal fin

breaking the surface of the water,

and they need to keep their eyes peeled.

Wow, look at this! Look at this!

Amazing!

Look, it's there. Just right there.

Just banked away at the last second.

And it's dived.

To stand a chance of being in the water with the sharks,

they need to stick around,

and shark expert Boone Hodgkin has developed a harmless technique

to keep the sharks close - by offering them a treat.

We'll throw some floaters, see if she'll take that,

and then we'll get you in the water.

Sadly, this shark isn't interested,

unlike some of the birdlife around here!

No action, you know.

It's what it is. It's hit or miss.

So we've got to find a player.

The crew head along the coast,

and it's not long before they find another shark.

Check that out!

That is amazing.

And the plan is put into action again.

Come on, girl.

You've got to aim it just right.

Cos you want it to sink right in front of her.

Yeah, she's coming round, look.

She's about to broadside right alongside us.

Look at that dorsal fin.

Let's see if she takes it.

Go on.

But, once again, there are no takers.

And, as the weather turns,

the crew have no choice but to head back to base.

I don't think I've ever tried to film an animal where the conditions

have to be so precise and so perfect as they do here.

We were out for maybe, I guess, six or seven hours this morning

and then the wind got up just a tiny little bit,

and that was too much for us to see any shark fins

and we've been basically sat around waiting for the last seven hours.

It's now eight o'clock at night and we're just going back out again.

And who knows what will happen?

But, for now, it's mirror-flat, calm, perfect.

Fingers crossed.

With the weather back on their side,

it's not long before the crew have another shark in their sights.

And it's time for cameraman Mark, and Steve, to get in amongst them.

But, despite appearances from above the surface,

the underwater team are facing a real problem.

They just can't get close enough to see the shark through the gloom.

Seriously?

I could see her dorsal fin on the surface.

She can't have been more than...

a metre and a half away from me.

But I still couldn't film her. Still didn't see her on camera.

Amazing.

Back at camp, director Charlie Bingham

reviews the underwater footage.

It's really frustrating because the sharks are there.

We're seeing them topside,

we're seeing them cutting through the surface

which is really exciting,

and Steve's been getting really excited about getting in the water,

but the visibility is terrible.

I think we're just going to have to rethink it.

The visibility's not going to change in the next day or two.

But, because they're so close to the surface

and actually breaking the surface,

I'm wondering whether our best chance

might actually be to get shots from the top.

We do have a drone crew with us.

So I think that's probably our best bet.

And, as the drone is deployed the next day,

it becomes apparent that Charlie's hunch was spot on,

and the team finally capture the remarkable images they were after.

The crew may have been thwarted in their underwater quest,

but from up high,

the beauty of this special Alaskan predator is revealed.

It just goes to show, doesn't it,

that not everything in wildlife film-making goes according to plan?

It rarely does.

No, no, and he got so close, didn't he?

But he just couldn't see that shark underwater.

Well, we've got more from the Wild Alaska Live team

this Wednesday at 8pm and, of course,

you can catch up with what they're doing

all this week online and via social media.

Now, those Pacific salmon that the sharks were feeding on,

and our own Atlantic salmon, travel vast distances

back to the rivers of their birth.

But they're not the only long-distance migrants

that travel a long way back to the UK every year.

And, in 2014, the One Show's Mike Dilger

went to the Norfolk Broads for an unusual encounter

with a very familiar long-distance migrant.

MIKE: The Norfolk broads are one of the UK's most important wetlands

and are the setting of some of the boating adventures

in the Swallows and Amazons books by Arthur Ransome.

But, 80 years after those books were published,

I've come here to find some real-life swallows

that have been doing a little boating of their own.

Ross Warrell has owned the Lady Ann, a traditional wooden Broads boat,

for nearly ten years.

It's used as a tour boat,

taking visitors to spot wildlife in these magical waterways.

But for the last couple of summers,

people haven't just been watching wildlife from the boat,

they've been watching wildlife ON the boat.

A family of swallows have taken up residence on board.

Just put your head around the corner here,

and if you look through this little gap here, you'll see the nest.

There's a mud nest just stuck to the wall here

and I can see beaks poking out.

-Can I have a look around the side?

-Help yourself.

Oh, that is fabulous.

One, two, three chicks.

I can see all their bills. That is remarkable.

Fantastic, isn't it?

I worried like anything about having them actually nesting on board

and thought, "This is not a very wise place for them to be."

As it turns out, they knew best.

Last year, we had two broods

successfully raised from that very nest.

And this pair of swallows came along about the third week in May.

-CHICKS CALL

-Oh, they're feeding.

I just heard the little buzz-buzz-buzz,

which means one of the adults must have whizzed straight in.

-"Feed me, feed me!"

-And the lucky one gets it.

A swallow uses its tail as a rudder,

moving it up, down and side to side to allow the bird

to make precision movements in the air.

It's fantastic, isn't it?

You might think having nesting birds on board would be bad for business

and the Lady Ann would have to be moored until the chicks are fledged,

but these parents go where the nest goes.

Swallows are fast flyers,

capable of flapping their wings 14 times a second in bursts of speed.

-There they are, just passed the boat there.

-Oh, lovely, look at that.

Ross, here we are 400m or 500m away from where you moored the boat,

and the birds are whizzing round, feeding

and just popping straight into the nest.

I've never seen it. It's amazing.

Their streamlined body shape and wings

make them very efficient flying machines.

When you think about it, it's perfect habitat.

All manner of aquatic insects are emerging -

mayflies, damselflies, stoneflies.

A swallow chick's weight will increase tenfold

in the first ten days of its life.

The parents will catch around 6,000 insects -

hoovering them out of the sky to feed their chicks - in just one day.

Keeping track of the boat is quite a feat

but then these birds are built to travel.

This is a species that has fabulous eyesight,

uses visual markers to go all the way from southern Africa to the UK,

so I suppose finding your boat in the Mere is no problem.

No, you think at first, how do they find you?

How do they put up with this moving target?

Well, yeah, as you said, they come from Africa,

they manage that quite well without someone holding their hand,

they're quite capable of finding me -

whether I'm here, a mile that way, a mile the other way.

They're cool with it.

Absolutely wonderful. Here they come.

LAUGHING: Look at that! Straight in.

It's a mobile home, they're not bothered.

And the swallows do benefit from life on a houseboat.

They're constantly working different areas and resources

-that are full of insects.

-Precisely.

And you are a protector as well.

I am a protector - any predators come anywhere near this boat,

during the daytime when I'm operating,

Uncle Ross will sort them out.

MIKE LAUGHS

Ross's little hitchhikers are a hit with the tourists too.

These are wildlife tours with a twist.

I've seen some birds nesting in wacky places,

but this location has to take the biscuit.

I think they should change the name of this boat from the Lady Ann

to the Swallow of the Norfolk Broads.

Those swallows came back to Rob's boat every year until 2016.

But, sadly, not this year.

Now, of course, the Norfolk Broads are a really important wetland area

and they're big - 300 square kilometres

of interconnected waterways and lakes that are known as Broads.

They may look natural but the Broads are actually flooded peat workings

dug in the Middle Ages to provide fuel

for the nearby towns of Norwich and Great Yarmouth.

Now, of course, the landscape of the Norfolk Broads

was once very different, as it was all across the UK,

and was home to very different animals as a result.

Now, some of those long-lost beasts are actually making a return,

-aren't they, Colin?

-They are, and one of the animals

that was once found right across the UK in rivers just like this one

was the European beaver.

But sadly, by the 16th century, they'd become extinct.

A trial reintroduction programme has been running in Scotland since 2009

but reports of beaver living wild on the River Otter in Devon

date back to 2007.

Nobody knows where these beavers came from,

but if there was any chance for them to be allowed staying in the wild,

the Devon Wildlife Trust had to find out more about them.

In 2015,

the beavers were captured from the wild

and brought to a makeshift veterinary centre

where experts conducted health checks.

There are actually two species of beaver -

the European beaver, once native to the UK,

and the North American beaver -

and on the surface, they look identical.

For the Devon beavers to remain living in the wild,

the Wildlife Trust had to first prove they were both disease-free

and pure European beavers.

The results were positive and so the trust

were able to re-release the animals back on to the River Otter,

close to where they were originally captured.

After the beavers had been released,

Martin Hughes-Games from Springwatch travelled to the River Otter

to find out just what kind of an impact the release of these animals

can have on our wild spaces.

-MARTIN:

-'Beavers were once native to Britain.

'But their return now is controversial,

'because of their ability to dramatically alter the landscape

'by building dams and lodges.

'Because they've been absent from England for so long,

'no-one knows what their return will involve

'or how much effect they will have on the landscape

'in and around our river systems.

'So, in 2011, the Devon Beaver Project was set up

'to assess their impact.'

Everywhere you look there are...

'Mark Elliott is a project manager and he showed me round.'

So, Mark, what was it like before the beavers came?

Well, it was an awful lot drier.

There was just this little tiny stream running through the site -

you can just about make out the old channel there.

-What, this is the actual channel here?

-Yeah, that was it.

But there was no other standing water on the site at all.

So all of the open water that we see here now

is all generated by the beavers.

-MARTIN LAUGHS Like this.

-Um...

That's a bit of a transformation, isn't it?

There's about 250 square metres of water

in some of these biggest ponds.

I mean, you can see the level of the dam now -

it's about a metre and a half, two metres high.

How many beavers does it take to do this? Dozens, presumably.

We've only got four in here at the moment.

-FOUR beavers did THIS?!

-Yeah.

It's all infilled with mud, presumably.

It's almost the mud that they start off with,

and then they add additional sticks for support.

So they're dredging the mud from the pond.

You see them surging forward,

push this mud up on to the top of the dam

and then they'll add sticks to that. I mean, it's remarkable, really -

we've got now about 600 cubic metres of water

standing in these ponds on the site.

So once they'd got their teeth in, there was no stopping them.

No, that's right, they really went for it.

One potential benefit of the creation of these pools

is that heavy rainfall is retained and released slowly,

helping to reduce flooding further downstream.

We're seeing all sorts of impacts here.

They are not called a keystone species for nothing.

-Come and have a look at this.

-Ooh! Tantalising.

'Some of the changes were expected,

'but one in particular was dramatic and surprising.'

So one of the things that's done really well is common frogs.

This is a huge area of frogspawn here, look.

Is it?

Oh, look at that, they've all hatched out.

-They've all just hatched.

-Wow!

So there's thousands and thousands of them here.

When you get your eye in, they're everywhere, aren't they?

-This is all one big area of them.

-It's black with them.

We counted 521 clumps across the site this year.

And that compares to only ten in the first year,

-when we put the beavers in.

-Ten?!

-Yeah.

There was nowhere for them to breed -

there was just no standing water at all.

So since the beavers have come,

they've created all of these amazing ponds

and the frogs are just absolutely loving it,

so numbers have just come up and up and up.

I suppose tadpoles, frogs - bottom of the food chain -

other wildlife will be benefiting from this?

Absolutely. Things like herons,

we're seeing a lot of herons here now

cos they're feeding on the frogs.

Grass snakes - you'd expect to see an increase in grass snakes

because again, they're feeding on the frogs.

They're just a really important part of the food chain.

It seems to me, though, that everything seems to be positive.

Everything seems to be benefiting from what the beavers are doing.

Are there any downsides?

Well, I think there's always going to be a mixed picture -

there's going to be some things that benefit

and some that don't do quite so well.

One of the concerns that's raised by salmon fishermen particularly

is about fish migration.

They struggle to get up over the dams

into the headwaters where they breed.

And that's what does happen in some cases -

if you've got a series of dams in the way

as the salmon migrate upstream to their spawning gravels,

then those dams prevent access to the upper tributaries.

But those impacts will vary a lot between catchment to catchment.

Although not everyone welcomes a return of these keystone engineers,

they're now living wild on the River Otter,

at least for a trial period.

But it will take several years of monitoring

before the full impact of their return to English waterways

is fully understood.

You always have to be careful

with any of these animal re-introductions.

But I, for one, think it is just great that one day,

both the beaver and the habitats that they create

could once again be a common sight across the UK countryside.

Yeah, it's interesting, isn't it,

that a lot of these animals that are being considered for re-wilding

here in the UK are actually species that you find in Alaska,

which just goes to show, we're not as different as you might think.

The UK was once home to not only beaver

but also the lynx, the wolf and even the Eurasian brown bear.

Now, of course, reintroducing any animal back into the wild

is a seriously complicated business

but we've had some huge successes here in the UK, haven't we?

-We sure have.

-And we're going to be bringing you one of those stories,

that of the sea eagle, later this week.

But we don't just want to show you the UK's wildlife and wild places

in the comfort of your own living room -

we are really hoping that we can encourage you to get out

and immerse yourself in nature,

and maybe have your very own wild river experience.

Now, many of you already do,

but if you need a little bit of extra inspiration,

then here's our guide to where the wild things are.

Wherever you are in the UK,

there will be a river not too far away,

a place for you to escape into the wild.

If waterfalls are your thing, head for the hills year-round.

Raging autumn torrents where salmon leap

or gentle trickling streams in summer.

In Wales, the Four Waterfalls Walk

in the Brecon Beacons is a favourite.

Dippers are a classic river bird.

Found along fast-flowing streams, they hunt for invertebrates

and nest under bridges in many of our rivers.

They can be spotted across much of the UK

but mainly in the west and north.

A great place to see both adults and fledglings

is the Peak District National Park in summer.

If it's mammals you're after, then the water vole is one of the cutest.

These semiaquatic rodents consume an incredible 80% of their body weight

each day, so need densely-vegetated river banks.

Special places to try and spot them include the wetlands at Magor Marsh

in Gwent, and the millponds of Cheddar Gorge in Somerset.

If you want to see a river otter,

the best plan is to head out at dawn or dusk.

These elusive animals are most common in Wales, south-west England,

Scotland and Northern Ireland.

Rivers have played a vital role in the development of many nations

and almost all of the world's capital cities

have a significant river flowing through them.

In the 16th and 17th centuries, as industry began to expand,

waterways were seen as the most reliable way

of moving around raw materials,

and big rivers like the Thames had navigation improvements.

The onset of the Industrial Revolution in the mid 18th century

saw the construction of a vast network of canals.

And it may not have been the original intention,

but these man-made rivers have now become valuable wild spaces.

As Lucy discovered when she headed

to the old industrial heart of England.

This leafy green by water

is the Staffordshire and Worcestershire Canal,

just west of Birmingham.

Chugging along slowly on a barge is a great way to appreciate it.

When this canal was built in 1771,

it joined the Staffordshire Potteries to Stourport

and then to Bristol,

and it also connected the Black Country to Liverpool.

In those days, it was the beginning of the Industrial Revolution,

and this waterway would have been busy with barges

carrying coal and iron back and forth.

Since 1978,

this has been a conservation area and it now provides over 47 miles -

75km - of habitat.

Hello, Paul.

'Paul Wilkinson is an ecologist who is dedicated to making the canals

'of the West Midlands a haven for wildlife.

'Thanks to Paul, an army of volunteers

'and some natural ingenuity, wildlife like kingfishers,

'water voles and even otters have returned in numbers.'

We're just coming up to the artificial kingfisher nesting site

just on this corner. They've put the little perch in,

it's actually been in eight years now.

It's suffered a little bit.

That's a beautiful spot, isn't it?

If I was a kingfisher,

I'd definitely be hanging out on that perch.

It's a complete contrast to how it would have been.

This would have been industrial, hard place, no space for wildlife.

This is the original re-wilding package.

The Trust do a lot of maintenance and monitoring on the canals

and Paul is putting me to work,

taking samples of the local water life.

This is the bottom of the food chain in a way, isn't it?

What supports all the kingfishers

and the otters and the showy animals

is these creepy crawlies in the water.

There's a kingfisher.

Oh! How fantastic!

I LOVE kingfishers.

I cannot believe we've been that lucky.

Beautiful.

Of all the animals that benefit from healthy canals and rivers,

Paul's most proud of the work that's been done

to encourage and grow the bat population.

The installation of dozens of bat boxes along the banks of the canal

has been a big success.

And Paul's taking me along one of his regular monitoring projects.

If I'm lucky, Paul's special licence to handle bats

may give me a close-up encounter.

Yeah, we've got a bat.

Yes! Fantastic.

What a score.

Wow, look at that.

This is a soprano pipistrelle.

When they flutter around you, because of the wings being out,

you get this idea that they're much bigger than they are.

The soprano pipistrelle's by far the commonest bat we get

along the waterways in our bat boxes.

So these are actually indicators of good woodlands, good water quality.

Because of their diet,

they need the amount of insects and aquatic insects in particular.

It takes so much energy to fly

and it takes so much energy for a little body to get warm,

they need lots of good-quality food.

And that food is found in great abundance around here.

So to witness just what an excellent location

this canal has now become for bats, Paul's brought me back after dark -

when the bats take to the wing.

We've brought bat detectors to tune into their wavelengths.

DETECTORS EMIT CHIRPS

Bats make a high-frequency sound, and this is converting that sound

into a lower frequency so that we can actually hear it.

Yeah, their calls are much higher than we can hear.

This is an entrance into a secret world, isn't it, really?

Well, if you turn them off...

CHIRPS REDUCE TO SILENCE

..who would know there were bats here?

-You'd never know, would you? You would never know.

-No.

-And suddenly, they're revealed.

-Mm-hm.

DETECTORS EMIT CHIRPS

So why are canals a particularly good area for bats?

You've got the water,

so straight away you've got the insects emerging from the water,

but also you've got the drinking so especially females, every night,

their first call is to have a drink of water.

And it's nice and calm water rather than fast, rushing streams

which can often catch them out.

And more importantly,

there's hardly any light pollution whatsoever on a canal like this.

Some people find them scary.

The fact is, they're fascinating,

there's so much we can learn from them.

The more and more we start to study them, we make them less cryptic.

You've got to love any animal that eat midges and mosquitoes,

-haven't you?

-Exactly. And in large numbers.

They're out there every night consuming harmful insects

and they don't want a salary.

SHE LAUGHS

A lot of people don't really like bats but it's worth knowing

that each one of those pipistrelles can hoover up 3,000 flying insects

in a single night.

And as someone who's just been savaged by midges here in Scotland

for the last few days, I say bring on the pipistrelles - we love you!

I couldn't agree with you more, Lucy.

They are a bit of a disaster around here sometimes.

But you know, we've got 18 different species of bats in the UK

and the biggest one, the noctule, could fit in the palm of my hand.

They feed only on insects

and many of them emerge from the water itself.

Using state-of-the-art thermal imaging cameras,

teams from the BBC Natural History unit were able to capture

this amazing scene of a variety of different bat species

all feeding on emerging insects over a lake in late spring.

Now, all of these insects, of course, are a great indicator

of the cleanliness of our water which, when healthy,

can support a really surprising variety of life.

And there's a very strange creature that lurks in our rivers

that few of us may ever have seen or heard of.

And, in 2015, The One Show's Miranda Krestovnikoff

went in search of them.

-MIRANDA:

-Morning on the River Frome.

Who would guess that under these quiet waters

lurks a beast from prehistoric times?

Imagine turning the clock back 400 million years

to a time before woolly mammoths, even before the dinosaurs.

It's hard to believe a creature that lived then

still exists here in the UK today.

I'm in Dorset to find one of the oldest,

rarest and, frankly, scariest animals in Britain.

My guide is Bournemouth University fishery scientist Adrian Pinder

who's promised me a close encounter with an ancient alien -

the sea lamprey.

So we're looking for sea lampreys but yet we're looking for them

in a freshwater river habitat - how exactly does that work?

Well, sea lampreys spawn in fresh water and then spend a portion

of their adult life at sea before coming back up the river

to spawn again.

At sea, sea lamprey are truly gruesome parasites

that attach themselves by their sucker mouths to fish

and grind away the flesh of their host.

By contrast, on their return to fresh water,

those mouth parts are used to construct their nests.

If we take a look at the gravel in front of us down here,

you can see there's a thin layer of algae all over it.

When the adult lamprey come upstream,

what they do is they start moving stones around

-so they're turning them over to create their nests.

-OK.

So we're looking for big patches of clean gravel, really.

Sea lamprey swim into UK rivers to breed, where they need shallow,

fast-flowing waters to reach at least 15 degrees centigrade

in order to spawn.

So, with a bit of luck, I'm hoping to see them in action.

There's a couple of patches up there that look a bit cleaner.

You've just found your first sea lamprey nest.

-Fantastic.

-I suggest we get kitted up and go and take a closer look.

OK, amazing.

Male sea lamprey exude pheromones into the water to attract females.

Then, together, they prepare nests in the gravel for spawning.

In order to see this behaviour,

I've brought along this specially adapted box with a Perspex bottom

and if I put this on the water,

I should be able to see through the reflections.

We're not going to disturb them, are we?

Well, these fish have only got one thing on their mind at the moment.

They're going to die after this,

so they're investing all their energy now into reproduction.

Oh! I can see it, I can see it, it's there.

That is incredible.

Let's take a closer look.

That's just amazing, they're enormous.

And they are moving the stones!

-They've got hold of a stone!

-Absolutely.

-That's incredible.

-That's how they construct the nest -

they're using their sucker disc to actually pick up these stones

and reposition them around this nest to create a crater

and, in doing so, that exposes some finer sediment

in the middle of the pit where they can then lay their eggs.

They will typically leave a big stone

in the middle of the nest that they use that as an anchor stone.

The stone just needs to be sufficiently heavy

so when they attach to one another and spawn,

this flow doesn't displace them and wash them out of the nest.

This one's spawning now.

Oh, my God. Look at that!

Oh, my word, so there was a rapid tail wiggle.

And the male will have wrapped his tail

around the back end of the female there.

She'll have drilled into the sediment and deposited the eggs

just sub-surface of that gravel.

-Wow.

-We should see a coiling event now. Look at this.

-Look at her go, look at her go!

-That is fantastic.

They are quite bizarre-looking fish, aren't they?

They're very prehistoric.

I used to think they were quite horrendous creatures,

to be quite honest, until I started filming them

and realised how beautiful they are.

What I really love about them is the fact

that the males and females work cooperatively,

moving stones from the nest to the perimeter of the nest.

There's no denying that these underwater oddities have evolved

to stand the test of time.

Even though these sea lampreys

are about to reach the end of their life cycle,

they have completed that essential task

of producing the next generation.

The lamprey may have a face that only a mother could love,

but I love them for their weirdness.

And of course, the UK is one of the key countries in Europe now

-for the sea lamprey.

-Absolutely.

Very important that we look after them.

And I've tried to go snorkelling with them every summer,

every time since I first saw them, I have to say,

I fell in love with them.

And I suppose because any creature that's been around

for hundreds of millions of years deserves respect.

Yeah. You've got to respect the lamprey.

Tomorrow on Wild UK,

we turn our attention to forests

and the wildlife that makes our wooded wildernesses their home.

Lucy discovers a project that's helping turn the success

of the pine marten in Scotland into something the whole UK can share.

Colin journeys deep into Kielder Forest.

And, well, if you go into the woods, you're sure of a big surprise.

We go behind the scenes with the Wild Alaska bear team.

Wonderful to be this close to a grizzly bear.

You can keep up with the latest news from the Wild Alaska Live team

all this week online.

And join us again tomorrow morning, 9:15, BBC One, for more Wild UK.