0:00:02 > 0:00:05Our planet is the greatest living puzzle in the universe.
0:00:05 > 0:00:09A collection of worlds within worlds,
0:00:09 > 0:00:13each one a self-contained ecosystem bursting with life.
0:00:17 > 0:00:19But how do they work?
0:00:21 > 0:00:23The intricate web of relationships
0:00:23 > 0:00:26and the influence of natural forces
0:00:26 > 0:00:31makes each microworld complex and unique.
0:00:33 > 0:00:35So to discover their secrets,
0:00:35 > 0:00:38we need to explore them one by one.
0:00:40 > 0:00:43Untangle their interlocking pieces
0:00:43 > 0:00:47and ultimately reveal the vital piece,
0:00:47 > 0:00:49the key to life itself,
0:00:49 > 0:00:53hidden deep within each of nature's microworlds.
0:01:06 > 0:01:08The Scottish Highlands.
0:01:08 > 0:01:11An ancient landscape of startling beauty.
0:01:14 > 0:01:16Craggy peaks peer over a terrain
0:01:16 > 0:01:19of thick forest and wide open space.
0:01:21 > 0:01:26Two contrasting habitats united by their battle with the elements.
0:01:28 > 0:01:32Presided over by Scottish emblems
0:01:32 > 0:01:34like golden eagles
0:01:34 > 0:01:37and red stags.
0:01:37 > 0:01:40And it's home to some of the rarest animals in Britain.
0:01:43 > 0:01:44The hand of man has been felt
0:01:44 > 0:01:46throughout the history of the Highlands,
0:01:46 > 0:01:49and yet its wildlife remains iconic.
0:01:55 > 0:01:58How have the Highlands remained a home for these species
0:01:58 > 0:02:00despite the pressure of the modern world?
0:02:02 > 0:02:08To find out, let's explore its deep forest and open heather moors,
0:02:08 > 0:02:11discover the impact of the elements on these landscapes,
0:02:11 > 0:02:14and the role of their key characters
0:02:14 > 0:02:18in keeping this remote corner of the British Isles wild.
0:02:26 > 0:02:29There's a famous saying about Scotland -
0:02:29 > 0:02:32it doesn't have a climate, just weather.
0:02:37 > 0:02:41Nowhere is this more true than in the Highlands.
0:02:43 > 0:02:48It's a landscape at the mercy of gale-force Atlantic winds.
0:02:50 > 0:02:52Winters have been known to hit -20.
0:02:53 > 0:02:56And when it rains, it pours.
0:02:58 > 0:03:02Have the elements had a hand in keeping this place wild?
0:03:03 > 0:03:07Up to five metres of rain fall here every year -
0:03:07 > 0:03:10that's the same as in some rainforests.
0:03:10 > 0:03:12With most other parts of Britain
0:03:12 > 0:03:14receiving less than a quarter of this,
0:03:14 > 0:03:17it's easy to see why humans might have chosen
0:03:17 > 0:03:19to set up shop elsewhere.
0:03:20 > 0:03:22But the Highlands' wild residents
0:03:22 > 0:03:24are made of sterner stuff.
0:03:26 > 0:03:29In fact, some rely on rain.
0:03:31 > 0:03:34From the soggy earth emerges a creature
0:03:34 > 0:03:36feared throughout the Highlands.
0:03:38 > 0:03:41The scourge of Scotland -
0:03:41 > 0:03:43the midge.
0:03:44 > 0:03:47This tiny millimetre-long vampire
0:03:47 > 0:03:50hatches from eggs laid in the rain-soaked ground.
0:03:55 > 0:03:57As the midge feeds,
0:03:57 > 0:03:59it sends off a chemical signal
0:03:59 > 0:04:02inviting others in the area to join the feast.
0:04:04 > 0:04:07Cutting the skin with their scissor-like mouthparts
0:04:07 > 0:04:09and sucking up the pooling blood.
0:04:14 > 0:04:18And with an estimated 40,000 capable of landing on a deer
0:04:18 > 0:04:21or similar-sized animal within an hour,
0:04:21 > 0:04:23they can make life unbearable.
0:04:25 > 0:04:27Midges die off before winter,
0:04:27 > 0:04:29but the change in seasons
0:04:29 > 0:04:32doesn't make life in the Highlands any easier,
0:04:32 > 0:04:35as the rain turns to snow.
0:04:37 > 0:04:41On cue, the mountain hare population turns from russet brown
0:04:41 > 0:04:43to brilliant white.
0:04:46 > 0:04:49The new coat is thicker and warmer,
0:04:49 > 0:04:52but it also helps to keep the hare safe from predators.
0:04:53 > 0:04:56A brown hare on a white background
0:04:56 > 0:04:58would stick out like a sore thumb.
0:05:05 > 0:05:08The ptarmigan employs the same colour-changing tactics.
0:05:10 > 0:05:13Its feathery feet increase the surface area,
0:05:13 > 0:05:14acting like snow shoes,
0:05:14 > 0:05:18preventing the ptarmigan from sinking into the deep snow.
0:05:19 > 0:05:23Humans would struggle to live in these cold conditions.
0:05:23 > 0:05:27But surprisingly, these hardy animals can only survive here
0:05:27 > 0:05:30because of the Highland's extreme weather.
0:05:32 > 0:05:35As Britain melted from its most recent ice age,
0:05:35 > 0:05:37around 12,000 years ago,
0:05:37 > 0:05:41animals adapted for arctic conditions were forced back
0:05:41 > 0:05:45to the very highest, coldest points of the British Isles.
0:05:46 > 0:05:51While humans busily colonised the rest of the newly temperate UK,
0:05:51 > 0:05:53the Highlands provided a climate
0:05:53 > 0:05:56in which these animal refugees could survive.
0:06:01 > 0:06:05So, has the tough climate kept the Highlands wild?
0:06:06 > 0:06:08While it's true that, as a rule,
0:06:08 > 0:06:11the highest, coldest, wettest parts of the world
0:06:11 > 0:06:13are some of the least developed,
0:06:13 > 0:06:16actually, the Highlands share a similar climate
0:06:16 > 0:06:19with major cities in other parts of the world.
0:06:19 > 0:06:22So, if weather alone does not keep a place wild,
0:06:22 > 0:06:26the Highlands must have another secret up their sleeve.
0:06:28 > 0:06:31There's less than 50 people per square mile here
0:06:31 > 0:06:34compared with 600 in the rest of the UK.
0:06:35 > 0:06:38Perhaps the landscape has a part to play.
0:06:42 > 0:06:45There's one very special, ancient habitat
0:06:45 > 0:06:48that's found nowhere else in the United Kingdom.
0:06:54 > 0:06:56The Caledonian forest.
0:06:56 > 0:06:59Dominated by the gigantic Scots pine.
0:07:01 > 0:07:04Growing up to 20 metres high
0:07:04 > 0:07:06and a solid three metres in girth.
0:07:08 > 0:07:12Each tree can live for a very respectable 250 years...
0:07:15 > 0:07:19..during which time, it supports an array of Scottish wildlife.
0:07:20 > 0:07:24It's the backbone of the Caledonian community.
0:07:27 > 0:07:32A familiar character is on the hunt for food among its branches.
0:07:32 > 0:07:35The red squirrel's agility allows it to reach
0:07:35 > 0:07:39the very top branches of the pine,
0:07:39 > 0:07:41home to some of the choicest cones.
0:07:46 > 0:07:50It's been estimated that a single squirrel can eat the seeds
0:07:50 > 0:07:53from as many as 20,000 pine cones in a year.
0:07:59 > 0:08:01Squirrels have the sharp incisors
0:08:01 > 0:08:03common with the rest of the rodent family,
0:08:03 > 0:08:06which they use to tear the tough cone apart.
0:08:08 > 0:08:10Perfect tools for the job.
0:08:10 > 0:08:12But even so, these teeth will need to grow
0:08:12 > 0:08:15as much as 15 centimetres a year
0:08:15 > 0:08:17to keep up with wear and tear.
0:08:23 > 0:08:27The squirrel knows just how tough the winters can be,
0:08:27 > 0:08:30so it plans ahead,
0:08:30 > 0:08:32burying stores for leaner times.
0:08:36 > 0:08:38Scent glands in its cheeks help
0:08:38 > 0:08:41to guide it back to the cache.
0:08:41 > 0:08:43But it might be months
0:08:43 > 0:08:46before the squirrel needs to excavate its hoard
0:08:46 > 0:08:50and, unsurprisingly, some seeds are forgotten
0:08:50 > 0:08:52or dropped by messy eating.
0:08:56 > 0:08:58On the forest floor,
0:08:58 > 0:09:00they have a chance of germinating,
0:09:00 > 0:09:02bolstering the pine population.
0:09:02 > 0:09:05It's a mutually beneficial relationship
0:09:05 > 0:09:07that's been going strong for millennia.
0:09:11 > 0:09:15Food is not the only reason the squirrel prefers the Scots pine.
0:09:16 > 0:09:20The bark blends perfectly with its rusty red fur
0:09:20 > 0:09:22and camouflage is all important
0:09:22 > 0:09:26when you have a predator that's equally at home in the branches.
0:09:32 > 0:09:35The pine marten rivals the squirrel's agility...
0:09:38 > 0:09:40..and in a high tree top chase,
0:09:40 > 0:09:42is one of few predators able to catch it.
0:09:54 > 0:09:57A smaller male wants in on the meal,
0:09:57 > 0:09:59but he's testing his luck.
0:10:02 > 0:10:05This pine marten is in no mood for sharing...
0:10:05 > 0:10:07IT SQUEALS
0:10:07 > 0:10:10..and chases the chancer out to a thin branch.
0:10:10 > 0:10:13IT SQUEALS
0:10:15 > 0:10:17The squirrel makes a good meal
0:10:17 > 0:10:20in an environment where every calorie counts.
0:10:20 > 0:10:24The young male will just have to find his own food.
0:10:27 > 0:10:28And by the looks of it,
0:10:28 > 0:10:30he could be going hungry.
0:10:36 > 0:10:38Pine martens are agile enough
0:10:38 > 0:10:41to also prey on the pine's resident birds.
0:10:43 > 0:10:46Like the Scottish crossbill,
0:10:46 > 0:10:49an endemic species found in Highland Caledonian forests.
0:10:54 > 0:10:58The bird's shape reveals its close relationship with the pine.
0:10:59 > 0:11:02Its curved, slightly crossed beak is perfectly adapted
0:11:02 > 0:11:05to prise seeds from tough cones.
0:11:09 > 0:11:11It eats little else.
0:11:16 > 0:11:18The tiny crested tit,
0:11:18 > 0:11:19one of Britain's rarest birds,
0:11:19 > 0:11:22is equally at home in the Caledonian forest.
0:11:24 > 0:11:26The tit supports the pine
0:11:26 > 0:11:29by winkling insects from crevasses in the bark
0:11:29 > 0:11:32and preventing burrowing larvae from doing serious damage.
0:11:34 > 0:11:38But birds are not the only species that groom the tree.
0:11:40 > 0:11:44The caterpillars of the pine looper moth and sawfly
0:11:44 > 0:11:46mimic the needles that they feed on.
0:11:46 > 0:11:51These caterpillars can defoliate a whole tree.
0:11:52 > 0:11:54But the Scots pine has an ally.
0:11:59 > 0:12:01Wood ants, on patrol.
0:12:06 > 0:12:09They detect their prey by vibration,
0:12:09 > 0:12:11stalking and attacking.
0:12:19 > 0:12:21The larvae may be twice the size of the ant,
0:12:21 > 0:12:23but this poses little problem,
0:12:23 > 0:12:26because these ants are team players...
0:12:28 > 0:12:32..dragging the larvae from the needles back to their nest.
0:12:33 > 0:12:37The largest ant in Britain has a suitably impressive home.
0:12:37 > 0:12:43Each metre-high mound holds up to 100,000 ants at a time.
0:12:44 > 0:12:48The nest is constructed almost entirely from pine needles.
0:12:53 > 0:12:56With a queen ant living for anything up to 15 years,
0:12:56 > 0:13:01the nest must be constantly repaired and improved to see out her reign.
0:13:02 > 0:13:05Each one is a feat of engineering.
0:13:10 > 0:13:11With the Scots pine providing
0:13:11 > 0:13:14both food and construction material for the wood ant,
0:13:14 > 0:13:17it's no wonder that their nests are a common site
0:13:17 > 0:13:19throughout the Caledonian forest.
0:13:23 > 0:13:25In fact, so many of the forest's species
0:13:25 > 0:13:28are interconnected with the Scots pine,
0:13:28 > 0:13:30relying on it for a food source,
0:13:30 > 0:13:32a nursery or a home,
0:13:32 > 0:13:36that it's known as a keystone species.
0:13:36 > 0:13:39The backbone of the forest community
0:13:39 > 0:13:42and where many trees grow together,
0:13:42 > 0:13:46the forest habitat supports larger species.
0:13:46 > 0:13:48CLICKING SOUND
0:13:50 > 0:13:52IT CLICKS
0:13:52 > 0:13:56This strange call belongs to the capercaillie,
0:13:56 > 0:13:59the largest member of the grouse family.
0:14:00 > 0:14:03The turkey-sized bird lives across much of Europe,
0:14:03 > 0:14:07but, in Britain, is predominantly found in the Highlands.
0:14:07 > 0:14:08IT CLICKS
0:14:08 > 0:14:11This is actually a mating call.
0:14:11 > 0:14:13It might not sound particularly enticing,
0:14:13 > 0:14:18but it's widely believed that the subtleties of the love song
0:14:18 > 0:14:20are too low for human ears to register.
0:14:21 > 0:14:23Capercaillies have been breeding in the Highlands
0:14:23 > 0:14:26since the ice age gave way to forest.
0:14:33 > 0:14:36Stands of Scots pine set a stage for their mating displays
0:14:36 > 0:14:40from the Highlands to Western Asia
0:14:40 > 0:14:43and the males are dressed to impress.
0:14:49 > 0:14:53With the affection of the more drably coloured hens at stake...
0:14:56 > 0:15:00..testosterone-fuelled tussles regularly break out.
0:15:00 > 0:15:01CLICKING
0:15:18 > 0:15:21The chance of injury is very real.
0:15:25 > 0:15:27The victor gets his girl
0:15:27 > 0:15:29and the chance to mate.
0:15:29 > 0:15:32IT CLICKS
0:15:35 > 0:15:38The Caledonian forests and their Scots pine
0:15:38 > 0:15:41are synonymous with the Highland wilderness.
0:15:43 > 0:15:47But they're only one habitat within this microworld.
0:15:49 > 0:15:51The forest exists side by side
0:15:51 > 0:15:54with another completely contrasting landscape...
0:15:56 > 0:15:59..moorland, as open as the forest is dense.
0:16:07 > 0:16:09Scotland's largest living mammal,
0:16:09 > 0:16:10the red deer,
0:16:10 > 0:16:12needs both these habitats.
0:16:15 > 0:16:18Deer feed on new pine shoots,
0:16:18 > 0:16:21but need open space to breed.
0:16:21 > 0:16:25IT BELLOWS
0:16:30 > 0:16:33Large males bellow across the heather,
0:16:33 > 0:16:36advertising their superiority.
0:16:38 > 0:16:41The stag rounds up a herd of females.
0:16:41 > 0:16:43By keeping them under his watch,
0:16:43 > 0:16:45he can ensure that no other male
0:16:45 > 0:16:48breeds with them and that only his genes are passed on.
0:16:51 > 0:16:54But that's easier said than done.
0:16:54 > 0:16:57Other males will want the females for themselves
0:16:57 > 0:17:00and are ready to fight for the right.
0:17:00 > 0:17:03THEY BELLOW
0:17:09 > 0:17:12These are ferocious battles
0:17:12 > 0:17:13to prove strength
0:17:13 > 0:17:14and determine dominance.
0:17:23 > 0:17:26The rut has been fought in the open heather moorlands
0:17:26 > 0:17:29for more than 11,000 years.
0:17:29 > 0:17:34It's the perfect arena, stretching for miles without a single tree,
0:17:34 > 0:17:37let alone sign of human habitation.
0:17:40 > 0:17:42Without natural shelter,
0:17:42 > 0:17:45it's no wonder humans avoided the moors,
0:17:45 > 0:17:48but deer are not the only animals to thrive.
0:17:49 > 0:17:52Despite first appearances,
0:17:52 > 0:17:56the open moorland is as rich with life as the pine forest.
0:17:59 > 0:18:02The red grouse is as dependent on the heather
0:18:02 > 0:18:05as its cousin, the capercaillie, is on the pine.
0:18:05 > 0:18:07IT CLUCKS
0:18:07 > 0:18:11Feeding on seeds, flowers and shoots as the seasons change.
0:18:12 > 0:18:14The heather, like the Scots pine,
0:18:14 > 0:18:17relies on the relationships with other species.
0:18:19 > 0:18:22Its striking purple flowers are pollinated by bees,
0:18:22 > 0:18:24while passing animals help
0:18:24 > 0:18:26to distribute its seeds.
0:18:30 > 0:18:32And it creates a territory
0:18:32 > 0:18:36for one of the most powerful birds on Earth.
0:18:37 > 0:18:39The golden eagle,
0:18:39 > 0:18:42a symbol of the wild Highlands.
0:18:42 > 0:18:45It's a predator, adapted for purpose.
0:18:47 > 0:18:51Keen eyesight allows it to scour the heather for movement
0:18:51 > 0:18:53from up to two kilometres away.
0:18:56 > 0:18:59Powerful talons and beak help it to dispatch prey
0:18:59 > 0:19:01many times its body weight.
0:19:04 > 0:19:08And this formidable bird needs these open spaces...
0:19:09 > 0:19:11..to hunt.
0:19:20 > 0:19:24Following a particularly cold winter, the snow's melted,
0:19:24 > 0:19:27but the mountain hare's fur hasn't quite caught up.
0:19:29 > 0:19:31The white that provided camouflage a month before
0:19:31 > 0:19:34is now more of an advertisement.
0:19:38 > 0:19:39With its two metre wing span,
0:19:39 > 0:19:41the eagle soars on wind currents,
0:19:41 > 0:19:44constantly spotting for movement below.
0:19:47 > 0:19:52While the hare is unaware of the danger overhead,
0:19:52 > 0:19:54the eagle locks in.
0:19:56 > 0:19:58But the hare is no sitting target.
0:19:58 > 0:19:59Once it spots the threat,
0:19:59 > 0:20:01it will sprint through the heather.
0:20:02 > 0:20:05By using pre-practiced routes that it knows are obstacle free,
0:20:05 > 0:20:09the hare is capable of hitting 60 kilometres an hour.
0:20:09 > 0:20:11But with the eagle topping out
0:20:11 > 0:20:13at three times this,
0:20:13 > 0:20:15it needs something more than speed to survive.
0:20:23 > 0:20:25So the hare dodges and weaves,
0:20:25 > 0:20:28throwing itself out of the eagle's trajectory.
0:20:32 > 0:20:36A last-minute zigzag saves the hare by a whisker.
0:20:44 > 0:20:47Heather plants can grow for around 30 years.
0:20:48 > 0:20:51After this time, they degenerate and die back.
0:20:51 > 0:20:55Bacteria in the soil will break them down.
0:20:55 > 0:20:58The increased nutrients that this breakdown provides
0:20:58 > 0:21:03is just enough for larger, hardy plants to begin to grow.
0:21:03 > 0:21:05Over time, heather will be replaced
0:21:05 > 0:21:10by trees and, eventually, forest.
0:21:10 > 0:21:13But something doesn't quite make sense.
0:21:13 > 0:21:17If this natural succession was taking place,
0:21:17 > 0:21:20the Highlands should be full of trees.
0:21:22 > 0:21:27Instead, Caledonian forest only exists in small pockets.
0:21:30 > 0:21:33This explains why some of the species that it supports
0:21:33 > 0:21:35are so rare in Britain,
0:21:35 > 0:21:38as there's just not enough habitat to go around.
0:21:40 > 0:21:42But it hasn't always been this way.
0:21:43 > 0:21:46Some 10,000 years ago,
0:21:46 > 0:21:49after the end of the last ice age,
0:21:49 > 0:21:51Scotland was covered in trees.
0:21:54 > 0:21:57These primordial forests would have been rich with life,
0:21:57 > 0:22:01wolves, bears, wild boar,
0:22:01 > 0:22:03animals missing from Scotland today.
0:22:03 > 0:22:04WOLF HOWLS
0:22:04 > 0:22:08So what has happened to the Highlands?
0:22:08 > 0:22:10How does a forest just disappear?
0:22:11 > 0:22:16What's allowed the heather to take hold in such vast areas?
0:22:16 > 0:22:20And how has the natural succession of the trees been halted?
0:22:24 > 0:22:29The soil below the heather reveals the answer to this conundrum.
0:22:30 > 0:22:34By studying remnants of the habitats from thousands of years back,
0:22:34 > 0:22:36scientists have been able to determine
0:22:36 > 0:22:41that there was still forest in the Highlands up to 5,000 years ago.
0:22:42 > 0:22:43Before disaster struck.
0:22:47 > 0:22:49The climate changed.
0:22:51 > 0:22:55A small fluctuation compared with the chill of the ice age,
0:22:55 > 0:22:59but enough to make the Highlands wetter.
0:22:59 > 0:23:01The deluge that followed was far more serious
0:23:01 > 0:23:04than the worst of modern-day Scottish winters.
0:23:06 > 0:23:08The forests literally drowned.
0:23:11 > 0:23:12It's thought that three quarters
0:23:12 > 0:23:15of the original Caledonian forest rotted away,
0:23:15 > 0:23:18creating vast bare spaces.
0:23:20 > 0:23:25Which suited not only the tough heather, but another species.
0:23:27 > 0:23:28Humans.
0:23:30 > 0:23:34Open land allowed communities to farm crops, build homes
0:23:34 > 0:23:36and raise livestock.
0:23:38 > 0:23:42For the first time, humans became a dominant Highland species.
0:23:44 > 0:23:46The climate eventually settled,
0:23:46 > 0:23:51but only a tiny 10% of the once vast Caledonian forest remained.
0:23:53 > 0:23:57The landscape that we recognise as the Scottish Highlands today
0:23:57 > 0:23:59had been created.
0:23:59 > 0:24:04This was, of course, great news for open-space-loving species
0:24:04 > 0:24:06like the grouse and mountain hare.
0:24:08 > 0:24:11IT HOWLS
0:24:11 > 0:24:12But many of the animals
0:24:12 > 0:24:14that relied on the forest -
0:24:14 > 0:24:15wolves,
0:24:15 > 0:24:17the capercaillie,
0:24:17 > 0:24:20red squirrel
0:24:20 > 0:24:22and bears became extinct.
0:24:25 > 0:24:28Those species that could survive were excluded
0:24:28 > 0:24:30to small pockets of woodland.
0:24:32 > 0:24:36Over the centuries, the land use of the Highlands shifted.
0:24:36 > 0:24:40Farms were cleared to make way for deer and grouse hunting.
0:24:40 > 0:24:43The Highlands were kept bare.
0:24:43 > 0:24:46Trophy species relied on healthy heather,
0:24:46 > 0:24:49and so patches were burnt to encourage new growth
0:24:49 > 0:24:52and extend the plants natural 30-year cycle.
0:24:58 > 0:25:02A new habitat was created,
0:25:02 > 0:25:06a patchwork of old and young heather growing side by side,
0:25:06 > 0:25:11in which not only the grouse, but all moorland species could flourish.
0:25:13 > 0:25:16But this wasn't a natural habitat.
0:25:19 > 0:25:23Man was artificially managing the Highland's wild populations.
0:25:26 > 0:25:30Humans had become an intrinsic part of the ecosystem.
0:25:34 > 0:25:36Scotland's heather moorlands were thriving,
0:25:36 > 0:25:40but the few remaining areas of forest and their inhabitants
0:25:40 > 0:25:41were still isolated.
0:25:43 > 0:25:46It was an environmental disaster that triggered the demise
0:25:46 > 0:25:49of the Caledonian forest 5,000 years before,
0:25:49 > 0:25:53so it's fitting that another would start to bring it back.
0:25:54 > 0:25:57But this time it wasn't brought about by natural forces.
0:26:05 > 0:26:08Two world wars left Britain's natural resources ravaged.
0:26:12 > 0:26:13New trees needed planting
0:26:13 > 0:26:16and, although their primary purpose was for timber,
0:26:16 > 0:26:20these forests also encouraged species back into Scotland
0:26:20 > 0:26:22that hadn't been seen in decades.
0:26:24 > 0:26:26Red squirrels re-colonised,
0:26:26 > 0:26:30supporting greater numbers of their predators - pine martens.
0:26:33 > 0:26:38Pine-loving populations of the rare crested tit and the crossbill grew.
0:26:43 > 0:26:47Landowners began to take responsibility for the wildlife.
0:26:48 > 0:26:52The focus shifted to forest protection and regeneration.
0:26:53 > 0:26:55But this posed a dilemma.
0:26:55 > 0:26:57Left to its own devices,
0:26:57 > 0:27:00the forest would naturally replace the heather habitat
0:27:00 > 0:27:04that now supported many more species than just the grouse.
0:27:04 > 0:27:08The regeneration of one couldn't come at the expense of the other.
0:27:11 > 0:27:15For these two habitats to co-exist in the Highlands,
0:27:15 > 0:27:18then humans would need to be actively involved.
0:27:21 > 0:27:22They'd have to site manage.
0:27:27 > 0:27:30Today, the Scottish Highlands are celebrated
0:27:30 > 0:27:32as the last truly wild place in Britain.
0:27:33 > 0:27:37But it is a wilderness under supervision.
0:27:39 > 0:27:43Forests are being planted and the heather managed.
0:27:43 > 0:27:46Species have been re-introduced.
0:27:46 > 0:27:50It is a microworld under reconstruction.
0:27:50 > 0:27:53One in which humans are as fundamental to success
0:27:53 > 0:27:56as any of its other animals or plants.
0:27:57 > 0:28:02The Scottish Highlands are, at once, both wild and controlled.
0:28:07 > 0:28:12People have had to learn how to go about regenerating an ecosystem.
0:28:14 > 0:28:18A long and delicate process that's still not complete.
0:28:19 > 0:28:23But the hope is that, under careful guardianship,
0:28:23 > 0:28:27these iconic characters and ice age survivors
0:28:27 > 0:28:32will have a place in the Highland landscape for centuries to come.
0:28:56 > 0:28:59Subtitles by Red Bee Media Ltd