0:00:32 > 0:00:34BIRDS SING
0:00:35 > 0:00:39A typical corner of the British countryside.
0:00:43 > 0:00:48The sort of place anybody would be happy to come for a leisurely springtime walk.
0:00:52 > 0:00:54Birds singing...
0:00:55 > 0:01:00..flowers coming into bloom, and a real sense of peace and quiet.
0:01:05 > 0:01:08But there's more to this spot than meets the eye.
0:01:08 > 0:01:13This is one of the least visited, most remote places in Britain -
0:01:13 > 0:01:18so remote that more people have reached the summit of Mount Everest than have stood where I am now.
0:01:25 > 0:01:28And yet, despite its isolation,
0:01:28 > 0:01:33more than 100,000 people pass right by here every single day.
0:01:36 > 0:01:41I'm just 25 miles from the centre of London,
0:01:41 > 0:01:47at the junction of two of the busiest motorways in Britain, the M25 and the M40.
0:01:50 > 0:01:54And yet, among all this noise, concrete and traffic,
0:01:54 > 0:01:58there's a hidden haven for wildlife.
0:01:58 > 0:02:02Britain is full of places like this -
0:02:02 > 0:02:04places we think of as wasteland.
0:02:05 > 0:02:09Abandoned. Derelict. Forgotten.
0:02:11 > 0:02:15Yet these little bits of land up and down the country add up
0:02:15 > 0:02:18to an area bigger than all our nature reserves put together.
0:02:18 > 0:02:22They may no longer be useful to us,
0:02:22 > 0:02:25but nature has moved right back in.
0:02:42 > 0:02:46So what is it about places like these that make them
0:02:46 > 0:02:48not just special for wildlife,
0:02:48 > 0:02:52but one of the most important habitats of all?
0:02:52 > 0:02:56In this, the final episode in the series, join me for a tour
0:02:56 > 0:02:59around the hidden corners of our countryside
0:02:59 > 0:03:02in search of secret Britain.
0:03:27 > 0:03:30'Our story starts 2,000 years ago,
0:03:30 > 0:03:33'when human beings were just beginning
0:03:33 > 0:03:35'to make their mark on the landscape
0:03:35 > 0:03:38'and have an impact on the native wildlife.'
0:03:38 > 0:03:40Thank you very much.
0:03:47 > 0:03:53I'm about as far north as you can get in the British Isles, on the island of Mousa in Shetland,
0:03:53 > 0:03:56and I've come to look at an ancient monument,
0:03:56 > 0:04:00but it's an ancient monument with some very special residents.
0:04:06 > 0:04:11The first people to arrive here, a group of Iron Age settlers,
0:04:11 > 0:04:15built a vast stone structure known as a broch.
0:04:15 > 0:04:17Nobody quite knows why.
0:04:21 > 0:04:25Then, as mysteriously as they came,
0:04:25 > 0:04:30they moved away, abandoning the island and its broch.
0:04:30 > 0:04:33But it didn't stay empty for long.
0:04:35 > 0:04:37TWITTERING
0:04:37 > 0:04:39Can you hear that?
0:04:39 > 0:04:43It's a sound that's been described as fairies being sick.
0:04:43 > 0:04:47Not very nice! It's actually storm petrels.
0:04:48 > 0:04:52Can hear them, but to see them, we've got to wait a bit longer.
0:05:12 > 0:05:14FLAPPING AND TWITTERING
0:05:21 > 0:05:23Who'd have thought that if you'd have come
0:05:23 > 0:05:27to a remote island off Shetland at dead of night in the middle of summer,
0:05:27 > 0:05:30that suddenly everything would come to life?
0:05:30 > 0:05:32And it has.
0:05:34 > 0:05:40And what was this great lump of cold stone is suddenly a kind of vibrant tenement block.
0:05:48 > 0:05:53There's this theory that they're being called to the right place by their mate.
0:05:53 > 0:05:58There's so many choices of hole here, it must be very confusing.
0:06:03 > 0:06:05And suddenly they'll pop into a hole.
0:06:09 > 0:06:12Storm petrels are little miracles of nature.
0:06:12 > 0:06:17Barely the size of a sparrow, thousands of these tiny birds
0:06:17 > 0:06:20come here for just a few weeks every summer
0:06:20 > 0:06:23to raise their young inside the safety of these walls.
0:06:26 > 0:06:30For the rest of the year, they live out on the open ocean,
0:06:30 > 0:06:34following fishing boats and picking up food from the surface of the sea.
0:06:36 > 0:06:38And even when they're breeding,
0:06:38 > 0:06:42one of the pair must still make a daily fishing trip
0:06:42 > 0:06:46before returning after dark to change shifts.
0:06:49 > 0:06:53What is it? Midnight - bang on midnight - and it's still not dark.
0:06:53 > 0:06:55GULL CALLS CUT THROUGH TWITTERING
0:06:55 > 0:07:01But you can hear the gulls are still calling, and that's why these petrels come in
0:07:01 > 0:07:06under cover of darkness, or as much darkness as they can get at this time of year.
0:07:06 > 0:07:10They know if they come in daylight, they'll be picked off by those gulls,
0:07:10 > 0:07:15so they're way out at sea and then risk coming in only when the light's going.
0:07:16 > 0:07:19That way, they'll be safe, they hope.
0:07:20 > 0:07:23So by nesting inside the broch,
0:07:23 > 0:07:26this particular colony of storm petrels
0:07:26 > 0:07:32has discovered the perfect sanctuary, hidden from the dangers of the outside world.
0:07:39 > 0:07:43I don't suppose those Iron Age settlers ever imagined that,
0:07:43 > 0:07:46so long after they abandoned this place,
0:07:46 > 0:07:48it would still be full of life.
0:07:51 > 0:07:55But that's the story of secret Britain.
0:07:55 > 0:07:59We move in, then move out, and nature takes over.
0:08:02 > 0:08:07And meanwhile, 2,000 years later and 800 miles to the south,
0:08:07 > 0:08:10the story continues.
0:08:14 > 0:08:18There are some parts of Britain that, to put it politely,
0:08:18 > 0:08:22you wouldn't expect to see in the tourist brochures.
0:08:22 > 0:08:27Canvey Wick in the Thames Estuary is one of them.
0:08:30 > 0:08:35But although this doesn't look like the sort of place you'd want to go out of your way to visit,
0:08:35 > 0:08:38the wildlife takes a different view.
0:09:02 > 0:09:07It's like a jungle down here. But then, this place has been called England's rainforest.
0:09:07 > 0:09:10You see, there are more rare species of insects here
0:09:10 > 0:09:15than there are in any other site in Britain of this size.
0:09:15 > 0:09:19And yet, to the untutored eye, Canvey Wick looks like wasteland,
0:09:19 > 0:09:23which isn't surprising, really, because that's what it is.
0:09:26 > 0:09:33Places like this - old industrial land awaiting development - are known as brownfield sites.
0:09:33 > 0:09:37But it's amazing how quickly they change colour.
0:09:41 > 0:09:45First to arrive are some rather surprising plants.
0:09:47 > 0:09:53You expect to find ragwort and thistles on waste ground, but rose campion?
0:09:53 > 0:09:56You expect to find that in your garden, but it's an escape here,
0:09:56 > 0:10:00and dotted around absolutely everywhere - masses of it.
0:10:00 > 0:10:04And I suppose you'd expect to find the odd orchid. No -
0:10:04 > 0:10:07an entire plantation of marsh orchids here,
0:10:07 > 0:10:11enough to make a wild-flower enthusiast drool!
0:10:16 > 0:10:19Hard on the heels of the plants come the insects.
0:10:19 > 0:10:22The brown-banded carder bee
0:10:22 > 0:10:27is now very rare because we've lost so many of our wild-flower meadows.
0:10:27 > 0:10:29But here, it's doing rather well.
0:10:31 > 0:10:35So what is it that makes this place not just good for wildlife
0:10:35 > 0:10:38but home to such an extraordinary range of species?
0:10:38 > 0:10:45Well, to find out why it's so special, we need to go back about 40 years.
0:10:45 > 0:10:47The 1960s,
0:10:47 > 0:10:54when owning a car was the ultimate symbol of freedom and the open road was truly open.
0:10:54 > 0:10:59As motoring gathered pace, we needed oil refineries,
0:10:59 > 0:11:01so they started to build one at Canvey Wick.
0:11:05 > 0:11:10Then, in 1973, it all went horribly wrong.
0:11:10 > 0:11:15A global oil crisis brought price hikes and fuel rationing.
0:11:15 > 0:11:20The firm that built the oil refinery here went bust, and it never opened.
0:11:26 > 0:11:31Eventually, the giant oil tanks that stood here were pulled down,
0:11:31 > 0:11:34and the land was set aside for redevelopment.
0:11:38 > 0:11:45Since then, despite the threat of the bulldozers, nature has been forcing its way back,
0:11:45 > 0:11:49taking advantage of this unique little corner of Britain.
0:12:03 > 0:12:08So with all this amazing flora and fauna, what a tragedy it'd be
0:12:08 > 0:12:13if this wasteland were to be covered in concrete.
0:12:13 > 0:12:15Well, the good news is, it won't be.
0:12:15 > 0:12:20Canvey Wick is to become our first brownfield nature reserve.
0:12:20 > 0:12:23So all this wildlife gets a reprieve.
0:12:34 > 0:12:41You can see how quickly plants and animals reclaim the places we've abandoned and colonise new areas.
0:12:41 > 0:12:47But what's really astonishing is exactly how they do it.
0:12:54 > 0:13:00There's a scruffy, yellow-flowered plant that's so common today we hardly give it a second glance.
0:13:00 > 0:13:05It just loves the messy bits we don't take care of, but there was a time
0:13:05 > 0:13:10when it could only be seen in rather more refined surroundings.
0:13:10 > 0:13:14Hence its name - Oxford ragwort.
0:13:16 > 0:13:18300 years ago,
0:13:18 > 0:13:23just about the only place you could find this particular type of ragwort
0:13:23 > 0:13:27was here in the Oxford Botanic Garden, and you still can.
0:13:27 > 0:13:31Here it is, in a bed labelled "daisies".
0:13:33 > 0:13:37This plant's forebears were brought to Britain from their native Sicily,
0:13:37 > 0:13:42where they grew on the solidified lava on the slopes of Mount Etna.
0:13:47 > 0:13:52But of all the exotic plants that grow here, the Oxford ragwort
0:13:52 > 0:13:59was the one with the best means of escaping the confines of the garden, and it did it like this.
0:14:03 > 0:14:11Each seed has its own tiny parachute of hairs that enable it to float away on the breeze.
0:14:15 > 0:14:20Oxford ragwort might have escaped the city's botanic garden by air,
0:14:20 > 0:14:26but in order to colonise the rest of the country rapidly, it needed to utilise another form of transport.
0:14:30 > 0:14:31WHISTLE
0:14:47 > 0:14:51The dramatic spread of Oxford ragwort coincided
0:14:51 > 0:14:55with the development of our early rail network,
0:14:55 > 0:15:00and the Victorian naturalist George Claridge Druce thought he knew why.
0:15:00 > 0:15:04"I've seen the seeds enter a railway carriage window near Oxford
0:15:04 > 0:15:11"and remain suspended in the air of the compartment until they found an exit near Tilehurst."
0:15:11 > 0:15:14That's over 30 miles away.
0:15:19 > 0:15:21And Claridge Druce was quite right.
0:15:21 > 0:15:27Blown along in the slipstream of passing trains, the seeds floated down onto the stone chippings,
0:15:27 > 0:15:33which closely resembled the lava rock of Mount Etna, their ancestral home.
0:15:33 > 0:15:40And because so few native plants could grow here, the ragwort took root and flourished.
0:15:44 > 0:15:46WHISTLE BLOWS AND STEAM HISSES
0:15:46 > 0:15:53And that's the secret of how one little plant spread throughout Britain.
0:15:54 > 0:16:01Railways aren't the only man-made network that creates surprising new opportunities for wildlife.
0:16:07 > 0:16:12Britain's major roads and motorways stretch for 6,000 miles -
0:16:12 > 0:16:16about the same distance as from London to Tokyo.
0:16:16 > 0:16:19To either side of these thundering carriageways,
0:16:19 > 0:16:24the verges cover an area bigger than the whole of Dartmoor.
0:16:24 > 0:16:29Unlike the farmland to either side, our roadside verges
0:16:29 > 0:16:33don't get sprayed with pesticides or ploughed up for crops.
0:16:33 > 0:16:35The result?
0:16:35 > 0:16:43A long, narrow nature reserve we all see as we speed past, but seldom, if ever, visit.
0:16:48 > 0:16:52And this hidden world is full of surprises.
0:17:07 > 0:17:13From the rare Adonis blue to the familiar hedgehog, they're all here.
0:17:29 > 0:17:35And there's one creature that lives here that's the only British mammal to outnumber us humans -
0:17:35 > 0:17:38the field vole.
0:17:43 > 0:17:48You'd think that with almost 80 million of these little rodents in Britain,
0:17:48 > 0:17:49they wouldn't be hard to spot.
0:17:53 > 0:17:59But from the vole's point of view, staying hidden is crucial to its survival.
0:17:59 > 0:18:02For in the sky above,
0:18:02 > 0:18:06a pair of eyes is staring intently downwards.
0:18:10 > 0:18:13The field vole has a dilemma.
0:18:13 > 0:18:19With a litter of hungry young to feed, she can't afford to stay put in the safety of her nest.
0:18:19 > 0:18:22But if she moves,
0:18:22 > 0:18:25she risks alerting the kestrel.
0:18:28 > 0:18:35With its own family to feed, the kestrel can't afford to lose a potential meal.
0:18:35 > 0:18:40The battle between predator and prey is about to begin.
0:18:43 > 0:18:47The vole checks constantly for danger.
0:18:54 > 0:18:59Head hardly moving, the kestrel's eyes stay locked on its quarry.
0:19:05 > 0:19:09The vole in its sights, it goes in for the kill.
0:19:32 > 0:19:36The kestrel chicks are the winners today.
0:19:36 > 0:19:42The vole and its family finally ran out of luck.
0:19:54 > 0:19:59Long before the roads and railways spread out across our land,
0:19:59 > 0:20:04another means of transport, Britain's canals, reigned supreme.
0:20:06 > 0:20:11But our canals haven't been used as a major transport system for over a century now.
0:20:11 > 0:20:16Today, we use them for leisure and pleasure, a haven of tranquillity,
0:20:16 > 0:20:20where you can float along without a care in the world.
0:20:20 > 0:20:22And they're a haven for wildlife, too.
0:20:28 > 0:20:33Water voles make their homes in the muddy banks.
0:20:35 > 0:20:38While a flash of orange and electric blue
0:20:38 > 0:20:41may be all we see of a kingfisher.
0:20:47 > 0:20:52And damselflies perform their elaborate courtship displays over the still, calm water.
0:20:55 > 0:20:58There's one other very special creature that lives here, too.
0:20:58 > 0:21:03It's one of our commonest reptiles, but one we hardly ever see,
0:21:03 > 0:21:08and it reveals just how important our canals are for wildlife.
0:21:11 > 0:21:13The still water of the canal
0:21:13 > 0:21:16is ideal for a predator like the grass snake,
0:21:16 > 0:21:21which, despite its name, prefers wetland habitats.
0:21:21 > 0:21:24The thick, lush vegetation along the banks
0:21:24 > 0:21:30is the perfect place for amphibians, the grass snakes' favourite prey.
0:21:34 > 0:21:36No wonder frogs hop so well!
0:21:43 > 0:21:47But it's the nature of the canal system as a whole
0:21:47 > 0:21:51that gives the grass snakes their most important lifeline.
0:21:54 > 0:21:59Just like our roads and railways, canals form a network of corridors,
0:21:59 > 0:22:03criss-crossing the country for mile after mile.
0:22:05 > 0:22:11Long, continuous, and fringed with green, they allow the grass snakes,
0:22:11 > 0:22:15and many other beautiful creatures, to find their ideal home.
0:22:28 > 0:22:30# La mer
0:22:31 > 0:22:37# Qu'on voit danser le long des golfes clairs... #
0:22:37 > 0:22:40From narrow boats to the wide, open ocean,
0:22:40 > 0:22:42we Brits just love the water...
0:22:47 > 0:22:52..and being in it, under it or on it!
0:22:52 > 0:22:54# ..La mer... #
0:22:54 > 0:22:59And when you're not at sea, there's no safer place to berth your boat than in a marina,
0:22:59 > 0:23:05where you'll be safe and sound and sheltered from the ravages of the wind, the waves and the weather.
0:23:05 > 0:23:08But as well as being a haven for boats,
0:23:08 > 0:23:13this place also provides protection for a hidden undersea world.
0:23:13 > 0:23:18It looks a bit murky to me, but they tell me it's an amazing spectacle.
0:23:23 > 0:23:27Well, I just had to see for myself!
0:23:41 > 0:23:43A secret undersea garden.
0:23:43 > 0:23:48But instead of flowers, you get these fantastic creatures...
0:23:52 > 0:23:55..peacock worms, clinging on to the pontoon.
0:24:03 > 0:24:05And these are sea squirts -
0:24:05 > 0:24:11believe it or not, a creature with which human beings share a distant ancestor.
0:24:11 > 0:24:13They all thrive here
0:24:13 > 0:24:20because the marina creates a unique environment, unlike any other along our coasts.
0:24:20 > 0:24:23And here's the reason why.
0:24:23 > 0:24:30When the tide comes in, it brings plankton-rich water through these sluice gates.
0:24:30 > 0:24:34As the water level falls, the sill of the marina
0:24:34 > 0:24:38stops some of it escaping, and the yachts stay afloat.
0:24:38 > 0:24:42So the secret here is that the tide doesn't really go out.
0:24:43 > 0:24:51Unlike their counterparts outside, life in the marina is never left high and dry.
0:24:51 > 0:24:57The creatures that live in this giant rock pool get the best of both worlds -
0:24:57 > 0:25:02fresh food twice a day and a sheltered and secure environment,
0:25:02 > 0:25:07ideal for some of the more delicate inhabitants, like seahorses.
0:25:22 > 0:25:26Mind you, careless yachtsmen drop all sorts of things in the water.
0:25:26 > 0:25:29I don't think this'll pick up Radio 2 again!
0:25:34 > 0:25:36I can't talk now.
0:25:36 > 0:25:38I'm under the sea!
0:25:41 > 0:25:45But nothing seems to bother this hefty lobster here.
0:25:45 > 0:25:48At this size, he's probably around 50 years old.
0:25:48 > 0:25:51He's got a bit of fight in him, though!
0:26:02 > 0:26:04They were right.
0:26:04 > 0:26:08It is an incredible, secret undersea world.
0:26:10 > 0:26:12Such a treat!
0:26:15 > 0:26:22Yet again, we created this place for ourselves, but nature benefits.
0:26:27 > 0:26:31And back on dry land, another leisure activity
0:26:31 > 0:26:35has created a unique refuge for one very special wild creature.
0:26:37 > 0:26:40Golf is, apparently, very popular.
0:26:40 > 0:26:44There are more than 2,500 golf courses in Britain,
0:26:44 > 0:26:48played on by 2.5 million golfers.
0:26:53 > 0:26:58And at some time or other, they always end up here - in the rough.
0:26:58 > 0:27:01Wish me luck.
0:27:04 > 0:27:06Ooh, not bad.
0:27:08 > 0:27:14Golfers may curse these little patches of long grass, but wildlife just loves them...
0:27:14 > 0:27:18even if some creatures are harder to find than a lost ball.
0:27:20 > 0:27:27I'm looking for one of our largest and most fearsome insects, and it's got a giant of a name -
0:27:27 > 0:27:29the great green bush cricket.
0:27:32 > 0:27:35(Come on. There you are.)
0:27:35 > 0:27:37(Don't jump, come on.)
0:27:37 > 0:27:42He's one of our largest insects, up to 5cm long.
0:27:42 > 0:27:46That's about as long as my thumb, you can see. Beautiful!
0:27:46 > 0:27:48Absolutely glorious.
0:27:48 > 0:27:52Legs more powerful than those of Linford Christie...
0:27:52 > 0:27:56and a much better jumper than Jonathan Edwards.
0:27:56 > 0:27:59Sorry, Jonathan.
0:27:59 > 0:28:01These are lone hunters,
0:28:01 > 0:28:06on the trail of smaller crickets and grasshoppers
0:28:06 > 0:28:08in the long, tussocky grass.
0:28:11 > 0:28:13And when they do catch their prey,
0:28:13 > 0:28:18those powerful jaws make short work of it.
0:28:23 > 0:28:26I'm sorry if you're eating your tea.
0:28:29 > 0:28:34Because we're so tidy now and keep cutting grass down and smartening things up,
0:28:34 > 0:28:38its habitats are getting fewer in number, and it really does like a life in the rough.
0:28:38 > 0:28:41So here it is - in the rough.
0:28:45 > 0:28:50Go on, then, you get back to your tea and I'll get back to mine.
0:28:50 > 0:28:55# Spem in alium... #
0:28:55 > 0:29:00For many plants and animals, the key to survival is stability -
0:29:00 > 0:29:06living in a place that doesn't change very much over time.
0:29:06 > 0:29:13And there's one secret corner of every parish in Britain that provides just that.
0:29:14 > 0:29:20From season to season, year to year and century to century,
0:29:20 > 0:29:24churchyards stay more or less the same -
0:29:24 > 0:29:29an undisturbed place where all God's creatures can find a home.
0:29:29 > 0:29:33Birds forage among the gravestones,
0:29:33 > 0:29:37or feed on berries from an ancient yew tree.
0:29:37 > 0:29:40Mammals are found here, too.
0:29:43 > 0:29:47And places like this hold one other ancient secret -
0:29:47 > 0:29:52one you can find in every single British churchyard.
0:29:52 > 0:29:57For in the midst of death, there is a very special form of life.
0:29:59 > 0:30:03There are things living in this churchyard that you could easily overlook.
0:30:03 > 0:30:06And yet they're all around me,
0:30:06 > 0:30:08on the gravestones,
0:30:08 > 0:30:10on the trees,
0:30:10 > 0:30:13even on the walls of the church itself.
0:30:13 > 0:30:16They're not plants and they're not animals,
0:30:16 > 0:30:19and yet they have an amazing lifestyle
0:30:19 > 0:30:24and, thanks to their age, an extraordinary story to tell.
0:30:24 > 0:30:26And the name of these organisms?
0:30:26 > 0:30:28Lichens.
0:30:31 > 0:30:34This churchyard on the Cornish coast
0:30:34 > 0:30:39is home to more than 120 different kinds of lichens.
0:30:39 > 0:30:44They blend in so well, they almost seem to be part of the stone itself.
0:30:47 > 0:30:50So what exactly are lichens?
0:30:50 > 0:30:54Do you remember in your school biology lessons being told about symbiosis -
0:30:54 > 0:30:58the working together of two organisms for mutual benefit? Well, that's lichens.
0:30:58 > 0:31:03They're a combination of a fungus and an alga, and as movie mogul
0:31:03 > 0:31:05Sam Goldwyn is reputed to have said,
0:31:05 > 0:31:10"Between us, baby, we can make something bigger than both of us."
0:31:10 > 0:31:14And they certainly do have some remarkable qualities.
0:31:16 > 0:31:21For a start, lichens are some of the oldest organisms here.
0:31:21 > 0:31:26Some of these individuals will have been growing since before the English Civil War.
0:31:26 > 0:31:28They're also among the toughest.
0:31:28 > 0:31:31Think of them as the SAS of the natural world.
0:31:31 > 0:31:34They can cope with almost anything.
0:31:36 > 0:31:42In winter, the temperature on this stone can drop well below zero,
0:31:42 > 0:31:47at which point the lichen shuts down its system completely.
0:31:47 > 0:31:52Under the baking summer sun, the surface temperature rises
0:31:52 > 0:31:57to over 50 degrees - as hot and dry as a desert.
0:31:57 > 0:32:01But as soon as the rain begins to fall,
0:32:01 > 0:32:03life for the lichen begins again.
0:32:05 > 0:32:11Now, lichens may be tough, but they do have an Achilles heel.
0:32:15 > 0:32:20"After a long and painful illness, the Lord permitted the cold hand of death
0:32:20 > 0:32:26"to do his office in the body and introduced his soul into a world of spirits."
0:32:26 > 0:32:281806.
0:32:28 > 0:32:31And coincidentally, that's round about the time
0:32:31 > 0:32:35when things started to get a bit tricky for Britain's lichens.
0:32:42 > 0:32:48Smoke and soot from the Industrial Revolution filled the air,
0:32:48 > 0:32:53and all over the country, lichens began to wither and die.
0:32:55 > 0:33:00But there was one place where they could still benefit from a clean environment -
0:33:00 > 0:33:02rural churchyards like this one.
0:33:02 > 0:33:07And now that our air is once more fit to breathe, lichens are spreading out
0:33:07 > 0:33:16from refuges like this and colonising our countryside, towns and cities once again.
0:33:16 > 0:33:22So next time you pass through a churchyard, just pause for a while and look at the lichens.
0:33:22 > 0:33:26I know they may not be the most glamorous part of our natural heritage,
0:33:26 > 0:33:30but when it comes to stamina and endurance, ha!
0:33:30 > 0:33:31You've got to admire them.
0:33:31 > 0:33:35MUSIC: "Pie Jesu" by Andrew Lloyd Webber
0:33:43 > 0:33:46WHISTLE OF DESCENDING ARTILLERY SHELL
0:33:55 > 0:33:58This is Salisbury Plain,
0:33:58 > 0:34:03the largest military training area in Britain.
0:34:03 > 0:34:1050,000 soldiers, hundreds of tanks and dozens of helicopters.
0:34:13 > 0:34:17You might think this would be a disaster for wildlife.
0:34:19 > 0:34:21But you'd be wrong.
0:34:22 > 0:34:29Salisbury Plain is home to some of our rarest and most specialised plants and animals.
0:34:30 > 0:34:35And the secret is, they aren't here despite the military presence,
0:34:35 > 0:34:38but because of it.
0:34:39 > 0:34:44On cold mornings, common lizards perch on discarded shells,
0:34:44 > 0:34:49as the heat from the metal allows them to warm up more quickly.
0:34:49 > 0:34:52And from a rather unusual vantage point,
0:34:52 > 0:34:56barn owls fly off in search of their prey.
0:35:04 > 0:35:09But the most remarkable story of how wildlife has found a way
0:35:09 > 0:35:14of surviving in this battle-scarred landscape involves this plant,
0:35:14 > 0:35:20the devil's bit scabious, and the butterfly that depends on it, the marsh fritillary.
0:35:26 > 0:35:30Marsh fritillaries are a rare sight in today's countryside.
0:35:30 > 0:35:36Like so many specialised creatures, they struggle to survive in the world of intensive farming.
0:35:40 > 0:35:44These butterflies spend their whole life in a little patch of grassland
0:35:44 > 0:35:48no bigger than a couple of football pitches.
0:35:48 > 0:35:50And they don't ask for much.
0:35:50 > 0:35:54All they need is the right soil, that very special plant,
0:35:54 > 0:36:00and one other rather unlikely ingredient - a spot of disturbance.
0:36:06 > 0:36:09Which is where these tank tracks come in.
0:36:09 > 0:36:14They're beginning to grow over a bit now, but where that topsoil was scraped off,
0:36:14 > 0:36:17and with it the seeds of those competing plants,
0:36:17 > 0:36:21the devil's bit scabious has managed to grow, and look under this leaf -
0:36:21 > 0:36:24the maroon-coloured eggs of the marsh fritillary.
0:36:24 > 0:36:30By the time these hatch, this plant's going to be about three feet tall.
0:36:33 > 0:36:37And that's what makes it so attractive to the marsh fritillary.
0:36:37 > 0:36:41Because the scabious grows so well on this churned-up ground,
0:36:41 > 0:36:44when those eggs hatch into caterpillars,
0:36:44 > 0:36:47it provides just what they need.
0:36:50 > 0:36:55The caterpillars set to work, devouring the very plant they live on.
0:36:55 > 0:37:01In just two months, they eat many times their own weight in leaves.
0:37:01 > 0:37:06Then they go into hibernation and emerge as butterflies the following spring.
0:37:07 > 0:37:12Putting all its eggs in one basket is a risky business,
0:37:12 > 0:37:14but here at least it works
0:37:14 > 0:37:19and, hopefully, next June will see another generation of marsh fritillaries
0:37:19 > 0:37:23flitting in the sunlight across Salisbury Plain.
0:37:27 > 0:37:32And all because of a little bit of disturbance.
0:37:34 > 0:37:38Perhaps they should rename it...
0:37:38 > 0:37:40the artillery fritillary.
0:37:52 > 0:37:57Sand martins spend half their lives under African skies.
0:37:57 > 0:38:03But like the marsh fritillary, when the time comes to raise a family,
0:38:03 > 0:38:07these little birds are very choosy about where they breed.
0:38:16 > 0:38:19At a sand and gravel quarry in Shropshire!
0:38:20 > 0:38:24To get here, they've flown more than 3,000 miles,
0:38:24 > 0:38:29crossing the Sahara Desert, the Mediterranean Sea
0:38:29 > 0:38:32and the whole of Western Europe.
0:38:32 > 0:38:36They may only weigh half an ounce, but sand martins
0:38:36 > 0:38:41really are one of the great global voyagers of the bird world.
0:38:43 > 0:38:50So why on earth don't they choose a quieter, more tranquil spot to nest?
0:38:51 > 0:38:54Well, often they do.
0:38:54 > 0:38:57Their natural home is a sandbank alongside a river.
0:38:57 > 0:39:01But as they know, these can be at risk of flooding,
0:39:01 > 0:39:05so this place provides the ideal alternative.
0:39:11 > 0:39:17And by nesting so far up this mountain of sand, high as well as dry,
0:39:17 > 0:39:22the sand martins and their growing chicks are well out of harm's way.
0:39:26 > 0:39:31But another, much rarer breeding bird takes a far greater risk.
0:39:38 > 0:39:45Right down among the mighty machinery in this Yorkshire quarry is a bird that chooses
0:39:45 > 0:39:48to nest on the ground - the little ringed plover.
0:40:04 > 0:40:09Despite the constant thunder from the heavy machines,
0:40:09 > 0:40:12a mother's instinct makes her sit tight.
0:40:12 > 0:40:17She'll ignore any threat to her own safety to protect her precious eggs.
0:40:26 > 0:40:30Little ringed plovers colonised Britain after the Second World War,
0:40:30 > 0:40:36taking advantage of the road-building boom that created so many new gravel quarries.
0:40:36 > 0:40:40And while it may not look like the safest place to nest,
0:40:40 > 0:40:43this actually has real advantages.
0:40:45 > 0:40:47For a start, the incubating bird
0:40:47 > 0:40:50can see all around it,
0:40:50 > 0:40:54so it'll notice if a ground predator like a fox approaches.
0:40:55 > 0:40:59And the pattern on the eggs blends in with the bare shingle,
0:40:59 > 0:41:03so aerial hunters like kestrels can't spot them, either.
0:41:06 > 0:41:09A few weeks later, if the plovers
0:41:09 > 0:41:13have managed to dodge the danger and the tyres,
0:41:13 > 0:41:16the first eggs will finally hatch.
0:41:17 > 0:41:19PEEP!
0:41:22 > 0:41:23PEEP!
0:41:26 > 0:41:28PEEP!
0:41:33 > 0:41:38This little fella taking his first faltering steps
0:41:38 > 0:41:41is so small he'd fit into a matchbox.
0:41:44 > 0:41:47Yet incredibly, while mum continues
0:41:47 > 0:41:50to incubate her remaining eggs, he must fend for himself
0:41:50 > 0:41:54and find tiny morsels of food.
0:42:02 > 0:42:08And if he does survive, in just three months' time, he and his siblings
0:42:08 > 0:42:13will fly thousands of miles south to spend the winter in Africa.
0:42:22 > 0:42:28So what happens to all these holes in the ground when we've finished digging stuff out of them?
0:42:39 > 0:42:43Here in Cornwall, a disused china clay quarry has been transformed
0:42:43 > 0:42:48into a whole new miniature world - the Eden Project.
0:42:51 > 0:42:55Eden attracts more than a million visitors every year.
0:42:55 > 0:43:01So now that we've moved back in, is there any room left for nature?
0:43:04 > 0:43:10This really is an amazing place - an entire self-contained biosphere,
0:43:10 > 0:43:14carefully designed to imitate a natural habitat.
0:43:14 > 0:43:17But does this have anything to do with wildlife?
0:43:17 > 0:43:23And isn't playing tapes of birdsong to imitate nature going just a bit too far?
0:43:26 > 0:43:32Except they're not playing tapes at all. That's a real, wild robin, singing his heart out.
0:43:32 > 0:43:36And the robins aren't the only ones.
0:43:36 > 0:43:39All sorts of other birds have found a way inside the dome.
0:43:39 > 0:43:44Once they're here, there's no need to worry about rain or snow,
0:43:44 > 0:43:48and no predators to threaten their eggs or chicks.
0:43:49 > 0:43:55What's interesting here is the change in the robins' behaviour. They're famously territorial
0:43:55 > 0:43:59and males will often fight with one another, sometimes to the death.
0:43:59 > 0:44:02But here, they're placid, sociable,
0:44:02 > 0:44:05even friendly with the neighbours.
0:44:12 > 0:44:16The way these birds have adapted to a totally new and artificial environment
0:44:16 > 0:44:21sums up the resourcefulness of Britain's wild creatures.
0:44:21 > 0:44:26For centuries, they've had to cope with the changes that we've made to the landscape,
0:44:26 > 0:44:28changes that haven't always been for the best.
0:44:28 > 0:44:30TRILLING SONG
0:44:31 > 0:44:35Some species, like these robins, have done rather well.
0:44:35 > 0:44:39Others, unfortunately, haven't.
0:44:39 > 0:44:43And it's to those that we really need to give a helping hand.
0:44:47 > 0:44:50In one corner of the English countryside,
0:44:50 > 0:44:53that's exactly what we're doing,
0:44:53 > 0:44:57in the final chapter of the story of secret Britain.
0:44:57 > 0:45:00SKYLARKS SING
0:45:00 > 0:45:03This may look like an ordinary field,
0:45:03 > 0:45:07but it actually has some pretty extraordinary qualities,
0:45:07 > 0:45:11qualities that make it really good for wildlife,
0:45:11 > 0:45:14like these plants - different varieties
0:45:14 > 0:45:17of a tough little group called sedums.
0:45:18 > 0:45:22They grow mainly in deserts and on mountains,
0:45:22 > 0:45:24where water's in short supply.
0:45:26 > 0:45:29If you look closely at the leaves,
0:45:29 > 0:45:33you'll see they're succulent and fleshy, brilliantly adapted to storing water,
0:45:33 > 0:45:36and the flowers are brim-full of nectar
0:45:36 > 0:45:41to attract insects, and insects attract birds.
0:45:43 > 0:45:47And I can hear one of my favourites now - the skylark.
0:45:47 > 0:45:50What a show-off, just like an operatic diva!
0:45:50 > 0:45:53And that's what makes this field so special.
0:45:53 > 0:46:00Skylark numbers have been declining over the last few decades, but here, they're out in force.
0:46:04 > 0:46:07Skylarks sing their song in the sky.
0:46:07 > 0:46:12But they make their nest at a much more humble level,
0:46:12 > 0:46:15down on the ground.
0:46:17 > 0:46:21Elsewhere in Britain, they nest on farmland,
0:46:21 > 0:46:25in arable fields with long grass to hide the eggs and chicks.
0:46:31 > 0:46:34But nesting on the ground creates one major problem.
0:46:34 > 0:46:40It means that the chicks are very vulnerable to predators such as hedgehogs, stoats and weasels...
0:46:41 > 0:46:47..so vulnerable that any individual nest only has a one-in-three chance of success.
0:46:47 > 0:46:52Fortunately for these particular skylarks, that's not a problem.
0:46:52 > 0:46:56There are no hedgehogs or weasels in this field, so they can nest in peace.
0:46:56 > 0:47:00And the reason there aren't any mammal predators here?
0:47:05 > 0:47:10Because this field is more than 30 feet up in the air,
0:47:10 > 0:47:15on the roof of the Rolls-Royce factory near Goodwood in Sussex.
0:47:21 > 0:47:24It didn't get here by accident.
0:47:24 > 0:47:29It was carefully designed to benefit both the company and the birds.
0:47:29 > 0:47:32The company does its bit for the environment,
0:47:32 > 0:47:36while the skylarks get a safe, secure place to nest.
0:47:38 > 0:47:43For the first time in thousands of years, since we originally settled
0:47:43 > 0:47:45on these crowded little islands,
0:47:45 > 0:47:49we're creating places not just for us
0:47:49 > 0:47:52but also with wildlife in mind.
0:47:52 > 0:47:57So at long last, in these secret corners of Britain,
0:47:57 > 0:48:01the plants and the animals, the birds and the insects
0:48:01 > 0:48:05can live happily alongside us.