The Heart of Wales Wild Wales

Wales is not a big country,

but packed into it is a vast array of different habitats

and a wealth of wildlife.

There are not many places in the world

where you can walk from mountain top, through moorland, along rivers,

through woodland, and on to the sea.

And all of that in just a few hours.

My name is Iolo Williams.

I've lived and worked with wildlife in Wales all my life.

And I want to share my passion

for Wales' wonderful variety of wildlife with you.

In this series, I'll be taking you all over the country in all weathers.

I'll be visiting fabulous landscapes.

I'll be sharing with you the insights I've learned

on this journey of discovery through Wales.

In this programme, we'll travel to the uplands of Llangollen

to see some extraordinary bird display.

Through the Bala area to find stoats.

From there to Newtown to watch the best nest-builder in Britain.

Then to Radnor to see roe deer.

And across the Cambrian mountains to Cardigan Bay

for another amazing bird display and a rare lizard.

And end in Aberystwyth to see an extraordinary exhibition by 20,000 starlings.

I begin in northeast Wales.

The beautiful Vale of Llangollen and the remains of Castell Dinas Bran.

Behind the castle is a large area of uplands,

which was once one of the best grouse moorlands in Britain

and the biggest in Wales.

Around 40 years ago, grouse shooting stopped

and the birds went into decline.

But today, there's a big drive to revive the grouse population

and the heather's been cut to improve the birds' habitat.

The best time to see the grouse is at dawn during early Spring.

The moon is just dipping down below the horizon here now

and there are at least 10 male black grouse

displaying on the bank opposite me over there.

That's my favourite noise.

It always reminds me of my childhood because I grew up in an area

where black grouse at that time were quite common.

They're incredible birds.

You've got to make a real effort

to come out and see black grouse display.

It's not something you'll see in your back garden.

You won't see it from your own armchair.

You've got to get up early.

You've got to come to these really isolated but always stunning places.

In Wales, it's on the edge of a moor, like this.

When you hear the initial call...

When the males first arrive they make this hissing call, like...

IMITATES GROUSE CALL

..the blood courses through my veins because I know I'm just about

to witness one of the best displays in the whole of the bird world.

Close up, male black grouse are spectacular birds.

This one is fighting for a carefully selected piece of land.

An area of ground known as a lek.

Although black grouse numbers have declined dramatically

over the rest of Britain, Wales has held on to its population.

There are now around 200 displaying males in Wales

and most of them live here.

It's important to retain the best position on the lek,

as it'll be the biggest and most powerful male at the centre

who will mate with 80% of the females.

The battle for this position is intense.

The red head parts, or wattles, are normally a quarter of this size,

but during leking they're engorged by blood to make them more visible.

The tail also transforms into a bright white fan.

This is purely a threat display, but a very elaborate one.

The dominant grouse is on the right.

Males will lek all year round, but it becomes more intensive

at the end of April, when the females arrive.

They've been attracted by the noise and the bright colours of the males.

The females are quite drab birds and that's because once mated,

they alone are tasked with incubating the eggs

and raising the chicks.

This dominant male is centre of attention for two females.

The other males stay warily at the fringes.

His long battle for territory, which has taken a full year,

has finally paid off, and mating takes place.

All that for a couple of seconds.

The holiday resort of Rhyl is not the obvious place

to make a detour on a journey through the wildlife of Wales.

But during the Winter, it's one of the key sites

to see a very striking and tough little bird.

These visitors have travelled thousands of miles

to be here on this particular beach.

These are snow buntings - smashing little birds.

We tend to associate them with the Arctic or the tops of the Cairngorms

and that's where they breed,

but in Winter, they move down to lower ground.

One of their regular haunts is this beach in North Wales.

You've got to ask yourself, why come here?

It's not the most scenic beach in the world.

But the reason is seeds.

They're seed-eaters, like all buntings,

and seeds blown by the wind get caught up

on the pebbles on the beach and amongst this vegetation,

this marram grass here, so it's ideal for them.

And because the beach is long enough,

if they exhaust the supply in a small area like this,

all they have to do is move along a little bit and move along again.

There's enough food here to last them all winter.

No other songbird migrates as far north as the snow bunting.

In many parts of the Arctic, it'll be the only songbird present.

It's incredibly hardy and flies north during the Spring to breed.

The snow buntings can be seen on this beach

most days during the winter.

You just have to spot them carefully on the pebbles.

They're no bigger than a sparrow, but a lot more colourful.

It's remarkable that this small flock of birds

have travelled so far to be on this beach.

Their parents, grandparents and great-grandparents before them

have probably made the same trip.

Each successive generation passing on the route

and the location of their feeding site to their offspring.

These are the Berwyn uplands.

It might be going a bit far to call this landscape a true wilderness,

but it is nevertheless a harsh environment

and about as wild as it gets in Wales.

I was born not far from here and as a youngster,

I used to walk these hills in search of wildlife.

It's one of my favourite places in the whole of Wales.

The wildlife here is difficult to find

and you don't usually see much on a casual trek.

But when you do find it, it tends to be very special.

This is an interesting valley.

It's Cwmpenanner near Bala and it's got its own microclimate here.

It's actually spring, not that you'd think that when you look around.

It also happens to be one of the best places in Wales to see stoats.

The main reason for that are stone walls.

Looking around here, you can se that they encompass most of the fields.

They radiate out like spiders' webs.

Stoats love stone walls.

They've got nesting birds in Spring,

they're full of mice and voles and rabbits all year round.

The stoats can den in here

and stoats don't like to venture out into the open.

So it means they can stick to the walls

and travel all along the valley here

without really venturing far from these walls.

I rarely see stoats these days,

so seeing one is always a fantastic event.

But finding one in white ermine fur is absolutely wonderful.

Not all stoats change to a winter coat.

Lowland animals generally retain their brown fur

throughout the winter.

Usually, you only get a fleeting glimpse,

but this one has been tempted out into the open by a dead rabbit.

I like stoats. They're great characters.

Busy, but always on the look out for danger.

A stoat usually catches live prey,

but in the winter months, it'll readily eat carrion.

They're tough, feisty little animals.

This spectacular falls is west of Bala in North Wales.

In this area of uplands,

water fuels an intriguing form of wildlife during the autumn.

Here, the combination of damp ground, simple sheep grazing,

and lack of fertilizer, makes this particular patch of farmland

a very special place for one group of fungi.

They're waxcaps and they emerge from the ground usually around October.

Over 30 different species have been recorded

on this small area of pasture.

They grow in different colours and shapes.

Underneath, they have this wonderfully intricate structure.

These are my favourites.

These are pink waxcaps, but also known as the ballerina.

Just look at the shape here. It looks like a ballerina in a tutu.

But it's also called the ballerina

because they're so elegant and delicate.

What's incredible is that this nondescript bit of farmland here

is the best known site for waxcaps in the whole of the world.

Waxcaps are renowned for their variety in colour.

Yet, we have no idea why they're so colourful.

It's not a defence mechanism to avoid being eaten.

They're not toxic and all are edible.

Neither do we know exactly why this particular piece of land

is so exceptional for them.

But they certainly like what this ground has to offer

because they thrive here.

Experts have tried to grow them in laboratories,

but they refuse to grow.

There are many mysteries surrounding waxcaps.

But for the time being, the questions are unanswered.

Most of the Welsh uplands have been set aside for sheep grazing,

as indeed they are in the rest of Britain.

At Nant y Cyrtiau farm, north of Bala, a place has been set up

to watch birds by a couple who share my passion for wildlife.

This wonderful garden belongs to John and June Watkins.

-You've got a fair old place here, haven't you?

-Yes.

-It's in a lovely location. You don't mind if I come in, do you?

-No.

To have a good look round.

-It's the kite time for you now as well.

-There's two.

-Coming into mating season, aren't they?

-Yes.

And there's greenfinches and all kinds of birds in here.

Goldfinches, greenfinches.

It's brought a lot of pleasure to us as well,

seeing the colour, the excitement.

The sparrowhawk, of course.

-People don't like the sparrowhawks. I like them.

-Do you?

People will pay big money to go to Africa to the Serengeti

to see lions bring down wildebeest.

But if you put out food in the garden for your birds,

a sparrowhawk comes in, and it's just the same, except it's free.

-And you can watch it from home.

-Yes.

You've put out a variety of food

-and that will attract a variety of different birds, won't it?

-Yes.

But it's alive here.

The sounds as well. You listen to the sounds. It's lovely, isn't it?

It is, really nice.

-That hedge is full of sparrows at the moment.

-Yes.

And a buzzard calling as well.

I tell you the one thing people forget about

that you've got here, is water.

People will put out food for the birds

and forget that birds need water just as much.

-It's just as important.

-Yes.

Here they come, look.

Feeding them in the winter, when the snow's coming down,

all the birds are flying around you

and you really can't put a price on that.

You really can't.

It always amazes me what a few scattered nuts

and lumps of fat will attract,

especially here on the uplands where food is scarce.

It doesn't take a lot of effort and the show is terrific.

In the summer, Nant y Cyrtiau is a very different place.

And it's the season for even more exotic visitors.

Some come from as far afield as Africa,

like this beautiful male redstart.

He's feeding his chicks in a nest he's built

inside a hole in the barn wall.

And here's the female.

Wales is one of the main destinations in Britain

for these summer visitors.

It's well worth keeping your eyes open

if you're near countryside buildings in Wales during the Summer.

They really are lovely birds.

Traditionally, the redstart is a woodland bird

that nests in holes in trees.

But it will readily take to holes in buildings too.

This pair has discovered a perfect residence

for two months in the Welsh uplands.

Later, we'll be encountering the extraordinary sights of boxing hares

and leaping salmon.

But first, I'm heading to my home patch.

I live in Mid Wales, near Newtown.

Near my house, there are many wonderful quiet lanes.

During spring, the trees and shrubs along the lanes

are full of nesting birds.

If you keep your eyes open,

you might see Britain's finest nest builder.

This is a typical long-tailed tit's nest.

It's tucked out of the way in a real jungle of thorns and bramble bushes.

They're incredible things, when you consider that every single nest

has got at least 1,000 feathers in it,

and some have even got 2,000 feathers.

The difference depends on where the nest is.

If it's in a fairly open, exposed area, it'll have more feathers.

If, like this one, it's in a nice, sheltered, warm spot,

it'll have fewer feathers.

When the female lays her eggs,

there's enough space in there for everyone.

But when those eggs hatch, and the chicks are about two weeks old,

like they are in this nest, there's hardly any room at all.

So what they do is they weave spiders' webs into the nest.

So as the chicks grow, the nest expands out.

It's a remarkable feat of engineering.

The nest is like a small rugby ball made of moss,

woven together with spider webs and hair.

It's camouflaged on the outside with lichen.

The adults are pink, black and white balls of feathers,

with a long, long tail.

The nest has taken around three weeks to build.

The inside is lined with up to 2,000 feathers.

The adults collect these off the ground

in the surrounding woods and farmland.

Sometimes they will pick them from the carcasses of birds.

The chicks grow quickly and need constant feeding.

They are fed on insect larvae.

And the adults return to the nest with food

virtually every minute of daylight.

They are also sometimes assisted by other adult long-tailed tits.

No-one knows for sure what benefitthese adults get from doing this,

but it's actually quite common in the bird world.

The River Severn is not far from my home.

Here, it's only a few miles from its source

in the Cambrian Mountains of Mid Wales.

At 220 miles, it's the longest river in Britain.

From here, it will flow over the border into England.

Along its banks, between Newtown and Welshpool,

lies one of my favourite nature reserves in Wales.

It's called Dolydd Hafren, which translates to Severn Meadows.

It's managed by the Montgomeryshire Wildlife Trust.

One of the characters I sometimes see at the reserve is Ivy Evans,

one of the Trust's founder members.

This is the part I particularly like because they planted this

and it's like coming through a long archway.

Yes. And it's not too dark.

-This is a nice bit.

-This is a lovely walk.

Say now, later on - March, April. Well, we are in March, but later.

You've got all the birds in this thicket, haven't you?

You've got great-tits and bullfinches and everything here.

It's a really nice little walk.

Magpie's nest, Ivy. Not always welcome.

Do you know what, my taid, my granddad, tells this tale.

I mean, taid was born in the 1880s.

And he remembers, in the village of Llanrug,

half the village going out to see this incredible bird.

A beautiful bird.

A lovely green sheen and pure white.

And within 15 minutes, the local keeper had heard about this.

'Bang' and the bird was dead.

-What was the bird? A magpie.

-Oh.

Until he was about 14, taid had never ever seen a magpie.

Shows you how things have changed.

-Gamekeepers, they'd kill them.

-They'd keep them down in those days.

-Yes.

-They really would. And they're nice birds.

Oh, beautiful.

But then, if you have a little wren or a little house sparrow,

they're beautiful!

Yeah, you're right. You're right. We take them for granted, I think.

For once, we are not at the reserve to look for birds.

We are here to look for hares.

It's one of the best reserves in Wales to see them.

But not this particular morning.

Can you see anything?

-No.

-No, nor me.

Well, I can't see anything. They're probably in there.

Well, Iolo, you are that much taller than me,

you can see into the ridges that I can't!

LAUGHTER

Come on, let's go and see what we can see down here.

I can see things down here, Iolo. See?

You look for the mice and voles, I'll look for everything else.

Cos I'm too tall to see those.

The best time to see hares is at dawn.

And generally when few people are around.

This is a courting couple.

The male is trying to mate with the female.

But the female is choosy.

And if the male persists, it leads to a boxing match.

It's the origin of the phrase, 'mad March hare.'

Hares are usually shy animals,

but during the spring, they change their behaviour.

The need to mate brings them out into the open.

They like traditional farmland,

especially where there are crops to hide in

and plenty of cover for themselves and their young.

And that's precisely what this reserve at Dolydd Hafren provides.

Its fields and hedges are managed like an old-fashioned farm.

The perfect place for hares.

Not far from Dolydd Hafren is another wildlife gem.

It's a beautiful woodland,

set in the grounds of an old manor hall near Newtown.

Whatever season you come here, the trees are full of birds.

BIRDSONG

This is the woodland at Gregynog Hall.

It's only a few miles from home, so it's my local patch.

And on a spring morning like this, it's wonderful.

It's really tranquil. Just me, the trees and the birds.

And that's it.

It always mystifies me why people rush through Mid Wales,

heading north to Snowdonia and Anglesey and the Lleyn Peninsula.

And they'll head south to the Brecon Beacons,

the Gower and Pembrokeshire.

It's wonderful for me because I get places like this to myself.

But it's a shame for those people,

because they're missing out on some real gems like this.

BIRDSONG

There's been a hall at Gregynog since the 12th Century.

And its 750 acres of ground are open to the public.

The big conifer trees are particularly interesting.

Like most conifers in Britain, they are not native trees.

They've been introduced and planted here.

Before the 18th Century, these trees didn't exist in Britain.

But they provide a welcomed additional habitat for one bird,

especially during cold nights.

This is a great tree. It's a Giant Redwood, or Wellingtonia.

Exactly the same as the big Giant Redwoods you have in California,

only this is only about 150-years-old.

So it's got a long way to go yet.

One of the unique things about it is this thick, soft bark.

And a common woodland bird takes advantage of this bark

to roost overnight on these freezing cold winter nights.

What it does, it digs a little hole, tucks itself in there

until the early morning, and then flies off.

But if we want to see it, we've got to come back here after dark.

BIRDSONG

-WHISPERS:

-And this is it. The treecreeper.

The bird has dug itself a little hole into that soft bark,

knowing full well it is going to be insulated all around.

His face and his belly and feet have gone right in,

and all that sticks out are his dense, back feathers.

He also knows that any passing owl is never going to see him.

Because those feathers blend in with the surrounding bark.

Now, that's a very cosy-looking bird.

It'll stay here until dawn.

Tucked in behind the bark,

and relatively safe from predators and the elements.

The county of Radnor is next to Herefordshire on the English border.

It's a soft landscape, made up of farmland, rounded hills

and occasional woodland.

And it's in these woodlands that roe deer began to recolonise Wales

around 20 years ago.

Although a native species of Wales,

for centuries, roe deer were extinct,

as they were in most parts of England.

They like a great deal of cover,

and the loss of woodland contributed to their downfall.

In the 1980s, they were reintroduced in Herefordshire,

and they spread to Radnor.

They can now be seen in many parts of Wales. A fantastic recovery.

There is one species, however,

that can truly be described as Radnor's very own.

They can only be found here,

near Hergest Ridge on the English border,

and nowhere else in Britain.

And it lives on these rocks,

which also happen to be the oldest rocks in Wales.

This is Stanner Rocks National Nature Reserve in Mid Wales.

And this beautiful and rather delicate little flower here

is the Radnor Lily.

Now, it's found on this one lump of rock,

and nowhere else in the whole of Britain.

Why is that?

Well, a combination of factors, really.

The rock is dark, so it absorbs the heat of the sun.

The soil is thin, it dries out quickly.

And because this, really, is a North Mediterranean plant,

this location is absolutely ideal for it.

The plant has a very good method of coping

with hot and dry conditions.

The leaves grow during the autumn and the plant flowers in March.

The Radnor Lily then dies back and exists as a bulb

during the hottest and driest part of the year.

So we have a plant which has found Mediterranean conditions in Wales.

Now, that must be unique.

Heading west from the English border into Mid Wales,

you quickly rise to a vast area of uplands.

These are the Cambrian Mountains.

They cover pretty much the whole central spine of Wales.

They are Wales' last true wilderness.

The biggest area of uplands in the country.

And it is to this forgotten part of Wales

that I escape during the summer.

Because that's the time to witness

one of the finest aerial displays in Britain.

A male hen harrier is sky dancing.

It is the breeding season and he is displaying to attract a female.

And here she comes, a very different bird.

Plainer, with brown feathers.

She's probably already incubating a nest full of eggs

amongst the tall heather below.

The male hen harrier has just come in with food.

Probably a meadow pipit or a vole.

And she is brown, she is all brown.

So she's the one who incubates the eggs.

She will sit in the tall heather down there, waiting for him.

He will be the one who hunts. He will bring in food for her.

When he gets above her, he whistles this low...

BLOWS BETWEEN HIS TEETH

Up she then comes. He will hold the food underneath him,

she flips under him, he then drops it last-minute,

she then takes that food and goes off to feed.

It's what's called the food pass.

And when you watch it in an area like this,

it is just, it's stunning. It's absolutely fantastic.

MUSIC PLAYS

Many of the great rivers of Wales, including the Wye and the Dyfi,

begin their life high up on the Cambrian Mountains,

and numerous small tributaries join them along the way.

As they cut into the hills, they form deep gorges

which are particularly impressive in the autumn after heavy rainfall.

This is the River Marteg,

a tributary of the Wye near Rhayader.

During the first two weeks in December,

it's a great place to see salmon jumping.

The salmon are on their way to their spawning grounds

higher up in the mountains.

These deep gorges must be a serious hurdle for them,

especially during a big flood.

But one of the most impressive gorges in Wales

is near Cemaes Road, not far from Machynlleth.

It's the River Twymyn, a tributary of the Dyfi.

It's a very dangerous place during a big flood

and a fall into the river would almost certainly be fatal.

There are some impressive salmon trying to battle their way up river,

but this gorge is so narrow and it's rained so much,

that the power of the water here is immense.

It's all froth, and the noise from the waterfalls is deafening.

The fish will sit it out,

dozens together in these deeper pools,

wait for the water to subside just enough

for them to make their way over this series of waterfalls,

four kilometres up river to the spawning ground.

This is one of the main routes for spawning salmon

travelling into the Welsh uplands from the West Wales coast.

Salmon can jump up to 10 feet. It's an incredible leap.

To achieve a big jump, they need deep pools to pick up speed,

they flap their tail fin vigorously

and propel themselves out of the water.

On the west side of the Cambrian Mountains

lies the forest of Nant yr Arian.

It's a conifer plantation typical of the Welsh uplands.

The forest overlooks a dramatic landscape,

especially in the autumn.

It's also one of the strongholds in Wales for red kites.

It's a place where you are guaranteed a view

of these spectacular birds.

That's because they are fed here daily by Ceredig Morgan.

You still feed, Ceredig, on the bare green patch there, do you?

Yes, the same place we've fed for the last, it's nearly 12 years now.

And look at the number of birds up now.

They're here already and there's an hour until kite feeding time.

Have the numbers have increased over the past 12 years?

We started with two, and when we got to four, we did throw a party.

Now, we're into the hundreds.

What we're going to try and do is,

Ceredig will put the food down in a fairly open patch over here

and I'm going to... where do you think?

Should I get in at the back among the tall trees?

Come through from the back, into the front, will be the best.

-And you'll be safe.

-Let's go and have a look.

I think that would be nice if it works.

Kites are terrific flyers and to see them at close range

is a rare privilege.

It's a case of Ceredig scattering the meat

and waiting for the first swoop.

Hoo!

For such a big bird, the kite is incredibly agile.

They've been circling above me for 15 or 20 minutes,

not quite sure whether to come down or not.

A buzzard came in and all of a sudden the floodgates opened.

Look at this!

From 10 metres up, they fold their wings and fall down,

and at the very last minute the wings and tail opens out

and the talons swoop down.

They grab the meat, they don't land at all.

They're up again and all of that in a split second.

There they are. Wow.

The wings and the tail are perfect brakes.

You always think when you see them come down like this

by the dozen, there's going to be a head-on collision.

But there never is, there never is.

They react like lightning. They'll swerve to the left or right,

avoid each other, whilst picking up the food.

The sky now is like something out of an Alfred Hitchcock film.

It's full of kites.

If you're heading west, Wales ends here.

This is Cardigan Bay.

You can see it's a bay.

We're right in the middle of it and look north,

that's the Lleyn Peninsula.

It stretches right out and Bardsey on the tip.

From here it looks like a series of islands.

The other way, looking south, this is Cardiganshire

and it bends around and we come to Pembrokeshire in the distance.

When I first came to these dunes 30 odd years ago,

they were much smaller.

But the sea is constantly dumping sand so it's got wider and wider

and it's one of a series of dunes in this part of the coast.

It now forms an impressive barrier between the sea and the land.

These are one of the most important wildlife habitats in Wales.

Though you'll be lucky to see one, Britain's rarest lizard lives here.

It's a sand lizard and he's looking for small insects

amongst the vegetation.

It's only found in a handful of locations in Wales,

the north west of England and southern Britain.

It's an endangered and protected species.

They especially like dune ridges and thick marram grass growth.

They're good places to hunt.

They themselves could be hunted, particularly by crows and gulls,

so they have good camouflage patterns along their bodies.

The sand lizards at Tywyn

form part of a nationwide reintroduction programme

which has been in place for nearly 40 years.

Here it has proved to be a great success.

They're breeding well and extending their range

along the dunes of Cardigan Bay.

A few miles up the coast from Tywyn lies the Mawddach estuary.

It's an exceptionally cold spell,

so cold that parts of the salt marsh has frozen.

I've never seen the Mawddach estuary look like this before.

The ground is frozen solid, there are mini icebergs on the water.

I think because we've had a succession of mild winters,

we forget that in really hard winters, even the estuaries freeze up.

That's bad news for the hundreds of thousands of birds

that come here from the north of Russia and Eastern Europe

to escape their hard winters.

It actually looks like the Arctic here now.

Despite the cold, hard ground inland, the mudflats are still soft.

That's why an estuary is so important to so many birds.

During a severe winter, it's the only place to feed.

These curlew, like most other waders feeding here,

are all migrants from Europe.

There's redshank.

And the black tailed godwit, using its beak to probe for worms.

These icy conditions may seem at odds with global warming

but severe short-term weather can occur in any climate.

Cold snaps such as this have occurred in Britain

during the past two winters.

When this happens, it can change the behaviour of local wildlife.

There is a very good example of this south along the coast.

Near the mouth of the Dyfi estuary, there is a large area of wetland

known as Cors Fochno.

The raised bog at its core is one of the largest in Britain.

But during winter it too can freeze, causing some of its residents

to move elsewhere to feed.

It's a fantastic chance to catch a glimpse of animals

normally hidden from view.

In the river that separates the bog from the sea,

I've discovered an otter hunting under the railway bridge.

You can spend a lot of time looking for otters.

You can stalk quietly in known hot-spots

and try to be inconspicuous.

But in reality, once they appear,

they're usually not bothered at all with humans.

This one is ignoring me and getting on with hunting.

There's plenty of food for it in the estuary.

Oh, wow.

It's not often you get this close to a wild otter.

He's up and down all the time, looking for fish maybe,

maybe a few crabs in here as well.

He's staring right at me.

This one has caught a small flatfish.

Although their main pray is fish, they'll eat whatever they can catch

including frogs, birds and other small animals.

And it amazes me how big and powerful they look

when I see them out of the water.

A very strong tail to help them swim fast, and sharp teeth.

This otter would have had to dive fairly deep to get that fish.

Climate change and sea level rise has had a dramatic effect

on the Welsh coastline, as in the rest of Britain.

Further up the Dyfi estuary, there is stark evidence of this.

On a very low spring tide, these structures appear in the mud.

If you're careful of the dangers of a rising tide,

they can be examined.

When you first come here and you see these big blocks,

you'd swear it's wood that's been washed down by the river

into the Dyfi estuary, but have a look at this.

They're tree trunks.

These tree trunks date back 5,500 years.

You've got oak, pine, hazel and birch.

At that time, a forest would have covered not just the land you see,

but it would have extended out into Cardigan Bay.

The Ice Age was still having a big influence.

It was locking a lot of water into the polar extremities.

All that remains are these few tree trunks.

You've got to time your visit here perfectly

because they're exposed only at the very lowest tide.

6,000 years ago, this would have been thick woodland

growing on the side of a steep valley.

But as the sea level rose, the land was flooded.

Mud and sand sediment built up, which not only covered the trees

but transformed the valley into a flat, muddy estuary.

Journey's end - the university town of Aberystwyth.

Probably not the place you'd expect to witness

a truly remarkable aerial display.

This time it involves 20,000 birds.

It's the end of a mid-winter's day.

Starlings are returning to town

after feeding all day in the surrounding countryside.

As the sun sets over the seafront, more and more arrive.

They drop from the sky and head for the pier to roost overnight.

Oh, wow! The sky is just full of starlings.

It's like fireworks exploding here, there and everywhere.

It's very hypnotic.

The big advantage with Aberystwyth pier is that it's so short.

The birds give this terrific display right over your head,

back and forth.

Also, you can hear them.

If you listen, you can hear thousands of wings.

They call to each other constantly.

Because you're so close to the spectacle here,

you feel that you're part of it.

Look at that. A wave of starlings coming over.

Oh, wow!

MUSIC

No-one really knows for sure why starlings do this.

Whatever the reason, it's an impressive sight.

The starlings roost under the pier.

They do this partly to keep warm

and partly to protect themselves from predators.

No fox, cat or peregrine can get at them here.

Nevertheless, they feel the need to jostle for the best perch.

The birds in the centre of the roost will not only be warmer

but safer too.

By dusk, thousands arrive.

Aberystwyth is one of only a handful of places in Britain

where starlings roost in towns.

Most of these starlings are birds from the continent.

They've come to Wales to escape the cold winter temperatures

and frozen ground of continental Europe.

They'll return to mainland Europe during the spring.

So we normally see this spectacle during the winter.

In the next programme, I'll be visiting Snowdonia

to see a magnificent osprey and relics of the Ice Age.

I'll be tracking wild goats and deer in Meirionnydd.

Enjoying the stunning beauty of Anglesey.

And the seals and shearwaters of the Lleyn Peninsula.

It's a journey to the rugged north west.

Subtitles by Red Bee Media Ltd