0:00:11 > 0:00:14We are an island nation,
0:00:14 > 0:00:18surrounded by seas and buffeted by winds...
0:00:20 > 0:00:24..with weather and seasons like nowhere else on Earth.
0:00:26 > 0:00:29Unpredictable, always changing,
0:00:29 > 0:00:32defining the nature of our extraordinary land...
0:00:34 > 0:00:39..and giving us the great British year.
0:00:53 > 0:00:55CRASHING OF WAVES
0:01:01 > 0:01:03A tempest is coming.
0:01:03 > 0:01:08One that will turn all life in Britain on its head.
0:01:08 > 0:01:10SEAGULL SQUAWKS
0:01:11 > 0:01:14All that is old will be swept away,
0:01:14 > 0:01:17clearing the way for something new.
0:01:23 > 0:01:27Over the next three months, the sun's power will fade.
0:01:31 > 0:01:36Wild weather will batter our shores, transforming the landscape.
0:01:45 > 0:01:49It's the time of last chances.
0:01:51 > 0:01:54Autumn is coming.
0:02:10 > 0:02:12BIRDSONG
0:02:12 > 0:02:16For most of us, the autumn equinox slips by unnoticed,
0:02:16 > 0:02:19but nature has already sensed this season's approach.
0:02:19 > 0:02:21ROBIN SINGS
0:02:27 > 0:02:31Trees are the first to feel the fading of the sun's energy...
0:02:32 > 0:02:35..and react in spectacular fashion.
0:03:01 > 0:03:05As October unfolds, acers and ashes,
0:03:05 > 0:03:10beeches and oaks, transform into a riot of colour.
0:03:13 > 0:03:16We British adore this time of year.
0:03:17 > 0:03:22On a single Saturday, 4,000 people enjoy the garden
0:03:22 > 0:03:24here at Stourhead in Wiltshire.
0:03:25 > 0:03:30A garden designed 300 years ago to showcase this magical autumn event.
0:03:41 > 0:03:44But there's a bittersweet sadness in this spectacle.
0:03:44 > 0:03:48It's a flamboyant display of death.
0:03:49 > 0:03:55The leaves are dying so that the tree itself might live.
0:04:03 > 0:04:06The leaves are the trees' solar panels,
0:04:06 > 0:04:09turning sunlight into energy.
0:04:09 > 0:04:12Soon there won't be enough sunlight to power them.
0:04:16 > 0:04:22In fact, they don't actually turn brown, they just become less green.
0:04:22 > 0:04:27They stop producing chlorophyll, revealing red and gold pigments
0:04:27 > 0:04:29that were always there, just hidden.
0:04:33 > 0:04:35The tree has already stored what it needs
0:04:35 > 0:04:37to get through the coming months.
0:04:37 > 0:04:40It doesn't need its leaves any more.
0:04:40 > 0:04:43Rather cleverly, it kills them off.
0:04:44 > 0:04:49For trees, survival is spectacular.
0:04:56 > 0:05:00There is no single moment that marks the start of autumn.
0:05:02 > 0:05:05Here in the Wye Valley, running between England and Wales,
0:05:05 > 0:05:09it usually stays green for a week longer than up in Scotland.
0:05:15 > 0:05:19Overall, the sweep of autumn moves from north to south
0:05:19 > 0:05:22until Britain is transformed.
0:05:35 > 0:05:39The days are getting shorter and there's a chill in the air.
0:05:42 > 0:05:45You might think the animals would be hunkering down.
0:05:45 > 0:05:50In fact, the shortening days stir them into action.
0:05:51 > 0:05:54But they must pick their perfect moment.
0:05:59 > 0:06:04In this web-strewn Dorset forest, battle-cries carry on the wind.
0:06:04 > 0:06:06DEER SQUEALS
0:06:11 > 0:06:13A male sika deer.
0:06:14 > 0:06:17He's spent all summer preparing for autumn
0:06:17 > 0:06:20and is in peak condition.
0:06:23 > 0:06:26He's gathered a harem of females.
0:06:26 > 0:06:30Over the next few weeks, they will each come into season.
0:06:31 > 0:06:35If his timing's right, he will father the next generation.
0:06:35 > 0:06:39But if he's made his play too early, the consequences could be fatal.
0:06:50 > 0:06:52There's a challenger in the forest,
0:06:52 > 0:06:55waiting for his chance to steal the harem.
0:06:57 > 0:07:02Any day now, the two males will meet in combat.
0:07:05 > 0:07:07While his rival puts on the pounds,
0:07:07 > 0:07:11the defending male puts all his energy into guarding his females,
0:07:11 > 0:07:14and the effort is taking its toll.
0:07:19 > 0:07:24As the days pass, the defender finds he's too busy to feed.
0:07:38 > 0:07:43Meanwhile, his challenger bides his time
0:07:43 > 0:07:46until he thinks the moment is right.
0:07:49 > 0:07:51He has chosen today.
0:07:51 > 0:07:55The challenger enters the ring.
0:08:08 > 0:08:11The pale challenger may be bigger,
0:08:11 > 0:08:15but the smaller, defending male is light on his feet.
0:08:36 > 0:08:40Both risk breaking their necks or being gored.
0:09:04 > 0:09:07The defender is getting a beating.
0:09:07 > 0:09:09He's fighting not just for his females,
0:09:09 > 0:09:12but now for his life.
0:09:39 > 0:09:41He's held on...
0:09:41 > 0:09:42just.
0:09:48 > 0:09:52And that's good enough. He's still king of the herd.
0:09:55 > 0:09:59But the price of victory may still be the death of him.
0:10:00 > 0:10:03In trying to father all the harem's offspring,
0:10:03 > 0:10:06he may lose a quarter of his body weight.
0:10:06 > 0:10:11And that will make surviving winter a very tough prospect indeed.
0:10:18 > 0:10:24In autumn's long past, we too had to prepare for the dark months ahead.
0:10:25 > 0:10:31For this, we put our faith in some particularly hardy plants.
0:10:32 > 0:10:36Plants that already had a strategy for surviving winter.
0:10:38 > 0:10:42They may not look much, but these were life-savers.
0:10:42 > 0:10:44The mighty kale.
0:10:45 > 0:10:48And the sturdy turnip.
0:10:50 > 0:10:55# Our day will come (Our day will come)
0:10:55 > 0:10:59# And we'll have everything
0:11:00 > 0:11:05# We'll share the joy (We'll share the joy)
0:11:05 > 0:11:09# Falling in love can bring (Oooh-ooh)
0:11:09 > 0:11:15# No-one can tell me that I'm too young to know
0:11:15 > 0:11:18# (Young to know)
0:11:18 > 0:11:22# I love you so (Love you so)
0:11:22 > 0:11:25# And you love me... #
0:11:28 > 0:11:32Kale leaves are filled with a natural anti-freeze
0:11:32 > 0:11:35and actually taste better after a frost.
0:11:39 > 0:11:42While bulb-like turnips will store for months...
0:11:43 > 0:11:47..allowing our ancestors to keep calm and carry on.
0:11:47 > 0:11:54# Our day will come. #
0:12:00 > 0:12:04By the end of harvest, everybody has to have a plan in place.
0:12:06 > 0:12:09A Red Admiral gorges on a late fallen plum.
0:12:09 > 0:12:12She might well die when the cold strikes,
0:12:12 > 0:12:14but she's already laid her eggs
0:12:14 > 0:12:17so a new generation will emerge next year.
0:12:24 > 0:12:27If you're going to brave it out, now is the time to get busy.
0:12:29 > 0:12:31Squirrels are cunning -
0:12:31 > 0:12:35hoarding nuts in secret stashes they can return to all winter.
0:12:37 > 0:12:40MUSIC: Theme from "The Great Escape"
0:12:40 > 0:12:44Swallows have already escaped to the sun.
0:12:46 > 0:12:50By now, they are well on their way to South Africa...
0:12:51 > 0:12:53..flying over 8,000 miles.
0:12:53 > 0:12:56It's a long and risky journey.
0:13:04 > 0:13:08Good luck, chaps. Hope to see you next summer.
0:13:14 > 0:13:16But perhaps the simplest escape of autumn
0:13:16 > 0:13:18is made by this little creature.
0:13:19 > 0:13:21A hazel dormouse.
0:13:23 > 0:13:25He doesn't bother hoarding food.
0:13:25 > 0:13:28Instead, he just eats...
0:13:30 > 0:13:35..doubling his tiny body weight to a chubby 40 grams.
0:13:36 > 0:13:39When the temperature drops, he takes to his bed,
0:13:39 > 0:13:41battens down the hatch...
0:13:42 > 0:13:44..and sleeps till April.
0:13:45 > 0:13:47Lucky fella.
0:13:53 > 0:13:57Late October has always been a time to take stock.
0:13:57 > 0:14:02If animals and plants were thriving, we'd have a good year too.
0:14:04 > 0:14:07And that was worth a celebration.
0:14:13 > 0:14:15Our autumn festivals coincide
0:14:15 > 0:14:20with the time of an ancient party to mark the end of harvest.
0:14:23 > 0:14:26A time of feasting...
0:14:27 > 0:14:29..and lighting fires.
0:14:32 > 0:14:34FIRE ROARS
0:14:35 > 0:14:37FIREWORKS EXPLODE
0:15:11 > 0:15:14By November, the residents of Britain
0:15:14 > 0:15:16are braced for the winter ahead.
0:15:21 > 0:15:24Britain may look dark and cold to us,
0:15:24 > 0:15:27but there's a band of travellers coming in.
0:15:30 > 0:15:34For them, this will feel balmy.
0:15:35 > 0:15:37GEESE SQUAWK
0:16:13 > 0:16:1950,000 barnacle geese - two-thirds of the world population -
0:16:19 > 0:16:22are fleeing the freezing Arctic
0:16:22 > 0:16:26and flocking to the tiny Scottish island of Islay.
0:16:34 > 0:16:37Their appearance is sudden.
0:16:37 > 0:16:40So sudden that locals once thought they were hatched
0:16:40 > 0:16:42from the barnacles on the sea shore.
0:16:47 > 0:16:50In fact, they've flown here from Greenland,
0:16:50 > 0:16:53more than 2,000 miles away.
0:16:56 > 0:16:58What have they come for?
0:16:58 > 0:17:00Britain's glorious grass.
0:17:05 > 0:17:10Our tough old grasses are perfectly suited to surviving the cold.
0:17:10 > 0:17:12They're still green and tasty.
0:17:25 > 0:17:29They eat as much as they can, as fast as they can.
0:17:39 > 0:17:42They have five months to prepare for the long flight home.
0:17:42 > 0:17:45Come rain, come shine,
0:17:45 > 0:17:49they feed and feed and feed.
0:18:09 > 0:18:12But they aren't the only visitors.
0:18:12 > 0:18:15Every autumn, Britain faces an invasion.
0:18:20 > 0:18:23Aberystwyth is the Biarritz of Wales,
0:18:23 > 0:18:25if you're a starling.
0:18:29 > 0:18:31These aren't local lads.
0:18:31 > 0:18:35They're tourists from as far afield as Russia.
0:18:37 > 0:18:42And there's millions more like them up and down the country.
0:18:43 > 0:18:48They're all drawn here because we're an island nation.
0:18:54 > 0:18:59The ocean keeps heat longer than the land, insulating us,
0:18:59 > 0:19:03keeping our climate milder and more hospitable than much of Europe.
0:19:06 > 0:19:09What's more, as life on land is shutting down,
0:19:09 > 0:19:13there's an enormous surge of life in the sea.
0:19:14 > 0:19:17Birds are flocking to the coastline,
0:19:17 > 0:19:20drawn for something just below the surface.
0:19:20 > 0:19:22BIRDS SQUAWK
0:19:25 > 0:19:27In their wake come common dolphins,
0:19:27 > 0:19:30which, in autumn, really are common.
0:19:31 > 0:19:33DOLPHINS SQUEAK
0:19:40 > 0:19:43They're following a sudden explosion in the number of fish.
0:20:06 > 0:20:10Some of the visitors are giants.
0:20:15 > 0:20:20Fin whales follow the dolphins, waiting to steal their food.
0:20:21 > 0:20:24Measuring twice the length of a London bus,
0:20:24 > 0:20:26only blue whales are bigger.
0:20:51 > 0:20:54But why does all this happen now?
0:20:56 > 0:21:00It's because of our position on the planet.
0:21:01 > 0:21:04In autumn, cold air is sucked down from the Arctic
0:21:04 > 0:21:09and meets the warm ocean around us, creating storms.
0:21:09 > 0:21:12And November is the stormiest month of all.
0:21:12 > 0:21:14THUNDEROUS ROAR OF WAVE
0:21:16 > 0:21:19Nutrients, which have lain dormant during summer,
0:21:19 > 0:21:23are mixed, like in a washing machine, bringing the ocean to life.
0:21:26 > 0:21:30Atlantic depressions create giant waves.
0:21:32 > 0:21:37Warm ocean air is sucked onto the cold land, bringing gales and rain.
0:22:02 > 0:22:06This is an elemental consequence of the fading sun.
0:22:06 > 0:22:10An unsettled time, which some find exhilarating.
0:22:37 > 0:22:41Monster waves, so prized by the surfers,
0:22:41 > 0:22:42pound our west-facing beaches,
0:22:42 > 0:22:46like here, on the Scottish islands of Orkney.
0:22:53 > 0:22:56For a baby grey seal, that poses a problem.
0:22:56 > 0:23:00Newborn pups can't swim.
0:23:02 > 0:23:06This baby needs to fatten up first before she's strong enough
0:23:06 > 0:23:10and insulated enough, to deal with the cold, rough sea.
0:23:11 > 0:23:15She only has 18 days before mum has to return to sea
0:23:15 > 0:23:16to feed for herself.
0:23:17 > 0:23:20SEAL PUP GRUNTS
0:23:21 > 0:23:24It's a race for mother and pup.
0:23:24 > 0:23:28Pups eat the equivalent of six packs of butter a day,
0:23:28 > 0:23:31sucking half their mother's body weight in fat-rich milk.
0:23:37 > 0:23:39And they'll need all the energy they can.
0:24:05 > 0:24:08In this cove, with its sharply shelving beach,
0:24:08 > 0:24:11big waves can be deadly.
0:24:16 > 0:24:21In a bad year, more than half these pups will be swept away,
0:24:21 > 0:24:23never to be seen again.
0:25:44 > 0:25:48This year, she's one of the lucky ones.
0:25:58 > 0:26:02Breeding at this time of year has its risks,
0:26:02 > 0:26:06but it's a risk these seals are prepared to take.
0:26:07 > 0:26:11In fact, 40% of the world's grey seal population
0:26:11 > 0:26:13breed on Britain's beaches.
0:26:20 > 0:26:23In fields and forests all over the country,
0:26:23 > 0:26:27preparation for the autumn storms have been going on for weeks.
0:26:33 > 0:26:37Have you ever wondered why trees shed their leaves?
0:26:37 > 0:26:40Like a ship lowering its sails in rough weather,
0:26:40 > 0:26:43they reduce their risk of damage by becoming streamlined.
0:26:47 > 0:26:50Sometimes the trees get caught out.
0:26:50 > 0:26:54The storms of '87 were so devastating because they came early,
0:26:54 > 0:26:57before the leaves had a chance to fall.
0:27:04 > 0:27:09This particular oak has got its timing right more than 700 times.
0:27:09 > 0:27:12The first autumn its leaves fell,
0:27:12 > 0:27:15Crusader knights were riding into battle.
0:27:24 > 0:27:28But with more than 1,000 million deciduous trees in Britain,
0:27:28 > 0:27:31what happens to all the leaf litter?
0:27:33 > 0:27:37It becomes a bounty for the unsung heroes of the forest.
0:27:50 > 0:27:53In ancient times, Aristotle called earthworms
0:27:53 > 0:27:57"the intestines of the soil" because they recycle
0:27:57 > 0:28:01thousands of tonnes of organic matter every autumn.
0:28:11 > 0:28:15Believe it or not, there are 25 native species of earthworm
0:28:15 > 0:28:17in Britain.
0:28:17 > 0:28:20Without them, we would be drowning in debris.
0:28:36 > 0:28:39They're not the only residents of the woodland floor
0:28:39 > 0:28:40that thrive in autumn.
0:28:42 > 0:28:47Fungi emerge from decaying wood, doing their bit to break down
0:28:47 > 0:28:50organic matter and return it to the soil.
0:28:52 > 0:28:57They're here all year, but this is their moment in the sun.
0:29:05 > 0:29:09In Britain, there are eight times more species of fungi
0:29:09 > 0:29:11than flowering plants,
0:29:11 > 0:29:15and yet who can name more than a handful of them?
0:29:17 > 0:29:19A few are poisonous to us
0:29:19 > 0:29:23but, to other fungi, they can be deadly.
0:29:25 > 0:29:28The porcelain fungus may look delicate,
0:29:28 > 0:29:32but it produces a fungicide that annihilates its competitors.
0:29:39 > 0:29:42There's no doubt fungi are weird and wonderful,
0:29:42 > 0:29:45but they are left standing when compared with another member
0:29:45 > 0:29:47of the underworld.
0:29:47 > 0:29:52Not a plant, not an animal, but something unique.
0:29:52 > 0:29:58A creature so foul, it has been called "the dogs vomit."
0:30:05 > 0:30:09Meet the slime mould.
0:30:14 > 0:30:17For much of the year, they live as single cells,
0:30:17 > 0:30:20but in autumn they come together.
0:30:22 > 0:30:25A relentless, shape-shifting, yellow goo,
0:30:25 > 0:30:29that scours the forest for bacterial food.
0:30:33 > 0:30:36The slime mould eats anything that gets in its path,
0:30:36 > 0:30:39devouring mulch and decaying matter.
0:30:42 > 0:30:45This blob provides an essential service
0:30:45 > 0:30:48in cleaning up our woodlands.
0:31:07 > 0:31:12Despite lacking an apparent nose, it hones in on its prey -
0:31:12 > 0:31:13a white fungus.
0:31:18 > 0:31:22# Now that we've chosen
0:31:22 > 0:31:25# To take all we can
0:31:26 > 0:31:30# This shade of autumn
0:31:30 > 0:31:34# A stale bitter end
0:31:34 > 0:31:38# Years of frustration
0:31:38 > 0:31:42# Lay down side by side
0:31:42 > 0:31:45# And it's only you
0:31:45 > 0:31:48# Who can tell me apart
0:31:48 > 0:31:51# And it's only you
0:31:53 > 0:31:56# Who can turn my wooden heart... #
0:32:08 > 0:32:13When all food is gone, they have a trick up their sleeve.
0:32:15 > 0:32:18A co-ordinated effort in mass-reproduction.
0:32:23 > 0:32:27How this colonial creature determines who does what
0:32:27 > 0:32:28is anyone's guess.
0:32:30 > 0:32:34Yet, some cells form stems, other cells form spores...
0:32:38 > 0:32:42..and the slime mould's tiny cells are scattered.
0:32:47 > 0:32:51Ready to spring into action when the good times return.
0:32:57 > 0:33:01It's all going on, on the forest floor in autumn -
0:33:01 > 0:33:04it's the after-party when the summer show is over.
0:33:11 > 0:33:13All these creatures thrive,
0:33:13 > 0:33:16because of something that Britain is famous for.
0:33:31 > 0:33:34Autumn is the rainiest of all seasons.
0:33:40 > 0:33:44On average, more than 30 centimetres of rain
0:33:44 > 0:33:46falls between September and November.
0:33:50 > 0:33:54And by November, the land is so waterlogged,
0:33:54 > 0:33:56the rain has nowhere to go.
0:34:04 > 0:34:09The Somerset Levels turn from summer crops...to autumn lakes.
0:34:14 > 0:34:16Villages become islands.
0:34:17 > 0:34:19Cheddar Gorge, a torrent...
0:34:21 > 0:34:25..as rivers across the country, burst their banks.
0:34:31 > 0:34:32For one animal,
0:34:32 > 0:34:35the rising water levels can't come soon enough.
0:35:00 > 0:35:02An Atlantic salmon.
0:35:02 > 0:35:04He's prepared for this moment all his life.
0:35:04 > 0:35:08Five years ago, he swam down this river to the sea.
0:35:14 > 0:35:17The deluge gives him the chance to fight his way back.
0:36:13 > 0:36:17He's against the clock - the longer it takes, the weaker he gets.
0:36:23 > 0:36:25He hasn't eaten since spring,
0:36:25 > 0:36:28and his body is beginning to fall apart.
0:36:35 > 0:36:39The shortening days are a sign that his time is nearly up.
0:36:48 > 0:36:51At last, he finds what he's come for.
0:36:57 > 0:36:59A female.
0:36:59 > 0:37:02She has chosen a spot in the river and dug a shallow nest
0:37:02 > 0:37:04in which to lay her eggs.
0:37:16 > 0:37:20Placing her body to the ground is a sign that she's nearly ready.
0:37:40 > 0:37:43As she begins to lay, he fertilises her eggs.
0:37:59 > 0:38:00Their job is done.
0:38:01 > 0:38:05If you're only going to do it once, you've got to make it count.
0:38:05 > 0:38:0810,000 eggs lie scattered on the river bed.
0:38:11 > 0:38:15If some survive, he will have achieved his goal.
0:38:30 > 0:38:33The male will now grow thin and his energy will fade.
0:38:36 > 0:38:42Soon, his remains will fertilise the river, where next year,
0:38:42 > 0:38:43his offspring will be born.
0:38:53 > 0:38:55His story is the essence of autumn.
0:38:57 > 0:38:59Clearing away the old,
0:38:59 > 0:39:02and sowing a seed for when the sun returns.
0:39:11 > 0:39:14It's December - the darkest month of the year.
0:39:15 > 0:39:18Since the September equinox, the sun has dropped in the sky,
0:39:18 > 0:39:22giving London just eight hours of natural light each day.
0:39:38 > 0:39:40What do we do to get through it?
0:39:40 > 0:39:42We fill our lives with light of our own.
0:39:45 > 0:39:47It's still three weeks to Christmas,
0:39:47 > 0:39:51but we find any excuse to brighten the long, dark nights.
0:40:16 > 0:40:19In John o'Groats in Scotland, the 18-hour night offers the perfect
0:40:19 > 0:40:25backdrop to nature's very own light display - the aurora borealis.
0:40:35 > 0:40:39More than 50 miles above the planet, charged particles,
0:40:39 > 0:40:42flowing past the Earth, collide with atoms to form light.
0:41:03 > 0:41:07In the far north, December nights are truly long and truly dark,
0:41:07 > 0:41:09and that makes it dangerous,
0:41:09 > 0:41:11particularly for small birds.
0:41:14 > 0:41:17All over the country, they'll do whatever they can
0:41:17 > 0:41:20to reduce the risk from nocturnal predators.
0:41:22 > 0:41:25In 21st century Britain, there are places where
0:41:25 > 0:41:28the long, dark nights of autumn just don't exist.
0:41:30 > 0:41:34Heathrow Airport - light 24/7.
0:41:44 > 0:41:48As sunset falls, the latest arrivals sneak in under the radar.
0:41:58 > 0:42:02They have a reservation - one that that will keep them safe
0:42:02 > 0:42:04in the dark and leaf-less nights.
0:42:10 > 0:42:12While heat radiating from the glass
0:42:12 > 0:42:16and concrete also makes this an unseasonably cosy setting.
0:42:24 > 0:42:27Making the most of it, are hundreds of pied wagtails.
0:42:33 > 0:42:36Wagtails are usually solitary birds,
0:42:36 > 0:42:39so it's hardly surprising each wants his own space.
0:42:50 > 0:42:52And nobody wants to sit near the toilet!
0:42:55 > 0:42:56With the lights on,
0:42:56 > 0:43:00it makes it really tricky for nocturnal predators to sneak up.
0:43:03 > 0:43:06Here, the wagtails are safe from hungry owls.
0:44:31 > 0:44:35Eventually, any warmth at all is just a distant memory.
0:44:36 > 0:44:40Sun-less December allows the serious cold to creep in.
0:44:44 > 0:44:45Autumn is over.
0:44:55 > 0:44:58Shards of ice form - known as hoarfrost.
0:45:13 > 0:45:18This is now a winter wonderland, with very different challenges.
0:45:25 > 0:45:27All the weight put on in the autumn feast
0:45:27 > 0:45:30will be the difference between life and death now.
0:45:44 > 0:45:47For some, the snow can't come soon enough.
0:45:51 > 0:45:53A few weeks ago, these ptarmigan were brown,
0:45:53 > 0:45:57but the shortening days triggered a fantastic transformation.
0:46:03 > 0:46:06This hare took the same gamble -
0:46:06 > 0:46:08switching its summer brown fur for white.
0:46:10 > 0:46:13Here in the Peak District, his gamble has paid off.
0:46:21 > 0:46:25If these mountains were still green, he would be easy prey for a buzzard.
0:46:38 > 0:46:40Switching from autumn to winter coat
0:46:40 > 0:46:43means the hare is now in his element.
0:46:46 > 0:46:49The buzzard will struggle to find food now -
0:46:49 > 0:46:53winter's arrival turns the tables for predator and prey.
0:47:06 > 0:47:09Christmas - time to wind down
0:47:09 > 0:47:11and wait for the new calendar year to begin.
0:47:20 > 0:47:23But the Earth has already started a new cycle.
0:47:25 > 0:47:27Subtly, since December 22nd,
0:47:27 > 0:47:30the days have started to get longer again.
0:47:36 > 0:47:39And while it will take many months for the sun's warmth to be felt,
0:47:39 > 0:47:42nature feels a change is on the way.
0:48:16 > 0:48:19Soon, the first buds will begin to form
0:48:19 > 0:48:20and the birds will start to sing.
0:48:26 > 0:48:29The promise of new life that happens every year.
0:48:46 > 0:48:51The coming and going of the sun affects our country in so many ways.
0:48:52 > 0:48:57Giving us our seasons and driving every living thing around us.
0:49:02 > 0:49:06Spring, summer, autumn, winter...
0:49:06 > 0:49:11there's nothing quite like the Great British year.
0:49:35 > 0:49:39We know what our British seasons are meant to be like -
0:49:39 > 0:49:41snow-white winters,
0:49:41 > 0:49:46springs bursting with new life,
0:49:46 > 0:49:49glorious hot summers,
0:49:49 > 0:49:52and woodlands rich with autumn colour.
0:49:55 > 0:49:57But during the filming of The Great British Year,
0:49:57 > 0:50:01the seasons weren't always, well, seasonal.
0:50:03 > 0:50:06In recent years, our weather seems unpredictable.
0:50:06 > 0:50:08Are our seasons changing?
0:50:08 > 0:50:11And is this having an effect on our wildlife?
0:50:15 > 0:50:18At the Met Office in Exeter, information about our weather
0:50:18 > 0:50:22is collected and interpreted by a team of expert forecasters.
0:50:23 > 0:50:25The weather in the UK isn't unpredictable.
0:50:25 > 0:50:27What it is, is variable,
0:50:27 > 0:50:31and that is because of where we are on the planet.
0:50:31 > 0:50:35Britain's weather is influenced by a whole host of factors -
0:50:35 > 0:50:38one of which is the jet stream, a fast flowing ribbon of air
0:50:38 > 0:50:41where cold and warm air meet, high in the atmosphere.
0:50:43 > 0:50:47The position of the jet stream can mean the difference
0:50:47 > 0:50:50between a damp December and a snow-covered Christmas.
0:50:54 > 0:50:56So it's hard to draw conclusions from the weather
0:50:56 > 0:50:58we get in a single year.
0:50:58 > 0:51:01To see if our seasons are changing,
0:51:01 > 0:51:04means looking at long-term trends in our climate.
0:51:04 > 0:51:08Weather is what you get and climate is what you expect.
0:51:08 > 0:51:11Weather changes from day to day, from hour to hour.
0:51:11 > 0:51:16Climate is all of those changes taken over a long period of time.
0:51:19 > 0:51:21Analysis of Britain's climate
0:51:21 > 0:51:25is done by the Met Office state-of-the-art super computer.
0:51:26 > 0:51:29By making a trillion calculations a second -
0:51:29 > 0:51:33equivalent to the processing power of 100,000 home computers -
0:51:33 > 0:51:37it analyses present conditions, and uses them to predict
0:51:37 > 0:51:41what will happen - short-term, and months and years in the future.
0:51:41 > 0:51:45What is actually happening over a long period of time is that
0:51:45 > 0:51:49the temperatures, both globally and in UK, are actually rising.
0:51:49 > 0:51:52Just because we get a cold year, or a wet year,
0:51:52 > 0:51:58or a hot year doesn't mean that we're not seeing the globe warming -
0:51:58 > 0:52:02we are seeing the globe warming and our long-term averages do show that.
0:52:02 > 0:52:05They show that actually, compared to 1960,
0:52:05 > 0:52:07the UK is about half a degree warmer.
0:52:08 > 0:52:11Despite some memorable cold snaps,
0:52:11 > 0:52:15since the '90s, we've had nine of the ten warmest years on record.
0:52:17 > 0:52:19When it rains, it rains heavier.
0:52:19 > 0:52:21And flooding is more frequent.
0:52:23 > 0:52:26Some would say our weather is getting more extreme.
0:52:27 > 0:52:31But how is that affecting the animals and plants of Britain?
0:52:34 > 0:52:38There's a whole army of observers who are keeping an eye on that too.
0:52:38 > 0:52:41The study of natural seasonal events is called phenology,
0:52:41 > 0:52:44and it's something that British people are pretty obsessed by.
0:52:46 > 0:52:50Last weekend, I was recording the first butterflies that I'd seen.
0:52:50 > 0:52:54It probably shows I'm a bit OCD myself,
0:52:54 > 0:52:57I record the family's first rhubarb crumble of the year!
0:52:59 > 0:53:05We may not realised it, but we are a nation of amateur phenologists.
0:53:05 > 0:53:09We notice the first buds,
0:53:09 > 0:53:13return of the migrant birds,
0:53:13 > 0:53:16newborn baby animals,
0:53:16 > 0:53:19or when we first cut the lawn.
0:53:19 > 0:53:22These indicators help paint a picture of seasonal events
0:53:22 > 0:53:25going on in the natural world.
0:53:25 > 0:53:28We're just fascinated by spring, we're desperate to see it return.
0:53:28 > 0:53:30We've been through a winter and we need some
0:53:30 > 0:53:34reassurance that the planet hasn't stopped tilting on its axis.
0:53:36 > 0:53:40Thousands of people contribute to surveys of seasonal change.
0:53:42 > 0:53:45And analysis of those observations is revealing how the plants
0:53:45 > 0:53:48and wildlife of Britain are behaving -
0:53:48 > 0:53:52not just on a yearly basis, but over decades.
0:53:55 > 0:53:58There is a very general trend for spring to be coming earlier,
0:53:58 > 0:54:01and you can see that in plants flowering,
0:54:01 > 0:54:05you can see that when migrant birds come back, and leafing of trees.
0:54:06 > 0:54:08Oaks are budding,
0:54:08 > 0:54:11snowdrops flowering,
0:54:11 > 0:54:14and fungi fruiting as much as ten days earlier
0:54:14 > 0:54:16than they did 50 years ago.
0:54:19 > 0:54:20Autumn is coming later,
0:54:20 > 0:54:23meaning the growing season is getting longer.
0:54:24 > 0:54:27Animals have changed their patterns too.
0:54:27 > 0:54:29Frogs are spawning sooner,
0:54:29 > 0:54:32birds like black caps, that were once seasonal visitors,
0:54:32 > 0:54:34are now seen all year.
0:54:36 > 0:54:38The difference may be just a few days,
0:54:38 > 0:54:43but does it matter if the timings of these natural events change?
0:54:43 > 0:54:46This study is not just interesting because it tells us
0:54:46 > 0:54:49spring is getting earlier and autumn later,
0:54:49 > 0:54:53but it tells us that species are not changing at the same rate.
0:54:53 > 0:54:58That there may be problems with species which rely on one another
0:54:58 > 0:55:00not remaining in synchrony.
0:55:02 > 0:55:05Birds must synchronise their breeding seasons with
0:55:05 > 0:55:07the boom in insects.
0:55:07 > 0:55:09If the caterpillars change their timings
0:55:09 > 0:55:11in response to earlier springs,
0:55:11 > 0:55:15birds could be out of step with their food supplies.
0:55:15 > 0:55:19But if everything moves in unison, things will stay in balance.
0:55:22 > 0:55:26Can nature tell us anything of seasons past?
0:55:34 > 0:55:37Deep in the vaults of the Natural History Museum in London
0:55:37 > 0:55:40are 150,000 butterflies and half-a-million moths
0:55:40 > 0:55:44collected by naturalists over the last 250 years.
0:55:48 > 0:55:51Collectors caught these highly prized specimens
0:55:51 > 0:55:54when they were in pristine condition -
0:55:54 > 0:55:57and that's very important, as it tells us when they emerged.
0:56:00 > 0:56:02The entire collection is being digitized -
0:56:02 > 0:56:05to work out how the dates of butterfly emergence in the past
0:56:05 > 0:56:07compares with today.
0:56:10 > 0:56:13This is the Meadow Brown butterfly, a common species in Britain.
0:56:13 > 0:56:16But would have appealed to the collector
0:56:16 > 0:56:18as it has a white hind wing.
0:56:18 > 0:56:21That's why that specimen was collected.
0:56:21 > 0:56:22You can see it was collected in
0:56:22 > 0:56:28Banstead, Surrey on 12th August 1956 by EL Bolton.
0:56:28 > 0:56:30Because it's got the actual day that it was collected,
0:56:30 > 0:56:32it's a very useful specimen.
0:56:34 > 0:56:36As they move through the collections,
0:56:36 > 0:56:39it's clear that butterflies used to emerge later,
0:56:39 > 0:56:41because springs were cooler.
0:56:41 > 0:56:44The trend for earlier emergence is getting more rapid
0:56:44 > 0:56:47when you compare butterflies from 50 years ago to today.
0:56:48 > 0:56:51It's marvellous that we can use the collections that people have
0:56:51 > 0:56:55built up over the last 250 years to answer questions
0:56:55 > 0:56:57that are concerning people today.
0:57:00 > 0:57:03So what will a British year look like in the future?
0:57:03 > 0:57:07And what does that mean for our Great British countryside?
0:57:07 > 0:57:11In 50-100 years' time, what the Met Office projections are suggesting
0:57:11 > 0:57:14is that for the UK we'll see hotter, drier summers
0:57:14 > 0:57:16and warmer, wetter winters.
0:57:16 > 0:57:20But that's a general trend - we'll still see the extremes within that.
0:57:23 > 0:57:26It looks like we can't get away from our variable weather,
0:57:26 > 0:57:30but if it's warmer - that will have implications for our countryside.
0:57:33 > 0:57:35The countryside will look different in the future.
0:57:35 > 0:57:37We'd like to know what those changes are.
0:57:37 > 0:57:39We'd rather not it come to us as a shock.
0:57:41 > 0:57:45Our place on the planet means we will always be a seasonal nation,
0:57:45 > 0:57:49but how different our seasons will be in the future,
0:57:49 > 0:57:51nobody can say for sure.
0:57:53 > 0:57:57Yet in 50, or 100 years' time - you can guarantee
0:57:57 > 0:57:59we British will still be talking about them.