0:00:12 > 0:00:18We are an island nation, surrounded by seas and buffeted by winds...
0:00:21 > 0:00:25..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 > 0:00:36And giving us:
0:01:02 > 0:01:06The passing seasons are what makes the Great British Year.
0:01:06 > 0:01:10Some days it feels like we get all four in a single day.
0:01:22 > 0:01:24We all feel the seasonal rhythms.
0:01:24 > 0:01:27They're part of who we are.
0:01:31 > 0:01:33CRICKET BAT HITS BALL
0:01:41 > 0:01:46For our wildlife, the seasons dictate every aspect of their lives.
0:01:46 > 0:01:48Timing is everything.
0:01:58 > 0:02:01We're all in this together,
0:02:01 > 0:02:06in a head-long rush through the ever-changing year.
0:02:06 > 0:02:13365 days, 12 months, 4 seasons...
0:02:13 > 0:02:15that shape our lives.
0:02:18 > 0:02:20As the yearly cycle begins,
0:02:20 > 0:02:24it's cold and quiet, but full of promise.
0:02:26 > 0:02:28Winter is here.
0:02:33 > 0:02:34New Year's Day.
0:02:34 > 0:02:37The sun is rising, but it won't climb very high.
0:02:44 > 0:02:46The days here are so short,
0:02:46 > 0:02:49there's little time for it to warm the ground.
0:02:53 > 0:02:56This is what defines our winter.
0:03:17 > 0:03:20In three months' time, spring will arrive.
0:03:33 > 0:03:38Then every plant, insect, fish, bird and mammal in the country
0:03:38 > 0:03:41will embark on a race to feed, grow and breed,
0:03:41 > 0:03:47but before then, it's going to get much colder
0:03:47 > 0:03:50and life is going to get much harder.
0:03:51 > 0:03:55A crisp, cold dawn.
0:03:56 > 0:04:00The year is only a week old, but snow is already on its way.
0:04:03 > 0:04:08At a disused aerodrome in Essex, it snows so rarely
0:04:08 > 0:04:12that many of the resident animals may never have seen it before.
0:04:18 > 0:04:22The derelict buildings are home to a male kestrel
0:04:22 > 0:04:23and a pair of barn owls.
0:04:27 > 0:04:31In Britain, we are never far from spectacular wildlife
0:04:31 > 0:04:34and these birds are - as the owl flies -
0:04:34 > 0:04:37just ten minutes from central London.
0:04:37 > 0:04:42The birds here are going to wake up to a very different world.
0:04:44 > 0:04:47A few hours of snowfall has transformed the place
0:04:50 > 0:04:53The voles and mice that these birds normally hunt are still here,
0:04:53 > 0:04:57but now they are hidden by a blanket of white.
0:04:59 > 0:05:02This poses a whole new set of challenges to the two birds.
0:05:02 > 0:05:05They approach the problem in different ways.
0:05:12 > 0:05:15The barn owl's trick is to fly so silently,
0:05:15 > 0:05:19that, although she can't see her prey, she can hear it.
0:05:25 > 0:05:27The kestrel's no stealth hunter.
0:05:27 > 0:05:31He is much more reliant on his sight than his hearing.
0:05:34 > 0:05:36Both birds are master hunters,
0:05:36 > 0:05:39but today the barn owl has the advantage.
0:05:40 > 0:05:43It's what you might call a clash of styles.
0:05:52 > 0:05:54To keep an element of surprise,
0:05:54 > 0:05:59the kestrel needs a telegraph pole to launch his ambush,
0:05:59 > 0:06:03while the silent barn owl is free to hunt on the wing.
0:06:03 > 0:06:06And she knows the airfield well.
0:06:06 > 0:06:10Under the snow, here are some corrugated iron sheets -
0:06:10 > 0:06:13just the spot to catch voles.
0:06:13 > 0:06:16Even from this height, she can hear the voles beneath the snow.
0:06:59 > 0:07:01The owl looks like she's struck lucky.
0:07:05 > 0:07:09Which is more than can be said for the kestrel.
0:07:44 > 0:07:47It's not been a good day for the kestrel,
0:07:47 > 0:07:50and as long as the snow is here,
0:07:50 > 0:07:52it's probably not going to get much better.
0:08:09 > 0:08:10Just a few miles down the road,
0:08:10 > 0:08:13they've escaped the worst of the snow.
0:08:13 > 0:08:17But there is something much more deadly in the January air.
0:08:19 > 0:08:21Frost.
0:08:30 > 0:08:33When water vapour in air hits a cold surface,
0:08:33 > 0:08:36it freezes into tiny crystals.
0:09:02 > 0:09:06Frost on a windscreen is a bit of nuisance,
0:09:06 > 0:09:08but imagine it if got inside your body.
0:09:10 > 0:09:14That's exactly what our plants have to deal with every winter.
0:09:14 > 0:09:18As water freezes inside a plant cell,
0:09:18 > 0:09:21it expands, putting pressure on the cell walls
0:09:21 > 0:09:23with a force powerful enough
0:09:23 > 0:09:27to burst a water-filled jar or even iron piping.
0:09:27 > 0:09:30For plants that aren't hardy,
0:09:30 > 0:09:34this is the moment in the year that that brings destruction.
0:09:35 > 0:09:39After the first freeze, even the morning sun can't help.
0:09:39 > 0:09:42The damage is done.
0:09:46 > 0:09:50The combined effect of thawing then freezing ruptures the cells,
0:09:50 > 0:09:52turning the plant to mush.
0:10:07 > 0:10:13This Dorset oak may look dead too, but don't be fooled.
0:10:16 > 0:10:20Beneath the bark, it's very much alive,
0:10:20 > 0:10:22protected by a natural antifreeze
0:10:22 > 0:10:25that runs through the cells of its trunk.
0:10:25 > 0:10:30It is simply biding its time for when the warmer months return.
0:10:30 > 0:10:36Thanks to this strategy, it has lived through 700 winters,
0:10:36 > 0:10:37and survived its first frost
0:10:37 > 0:10:41in the days when medieval knights roamed the land.
0:10:50 > 0:10:54This red squirrel is concerned with right now.
0:11:04 > 0:11:06Her warmth comes from the energy in the nuts
0:11:06 > 0:11:08that she stored away months ago.
0:11:26 > 0:11:28On a frosty January morning,
0:11:28 > 0:11:32it's not just squirrels that need food to keep warm.
0:11:32 > 0:11:37This is the toughest time of the year for our wild birds.
0:11:37 > 0:11:42Which is why so many turn to us for help.
0:11:42 > 0:11:45Thank goodness for bird tables.
0:11:48 > 0:11:50When you consider that some birds
0:11:50 > 0:11:53need to eat a third of their body weight every day,
0:11:53 > 0:11:57it's not surprising that, on a cold snap,
0:11:57 > 0:12:01bird feeders attract a veritable feathered feeding frenzy.
0:12:12 > 0:12:15Our birds are not big on sharing.
0:12:25 > 0:12:29Sparrows, in particular, just can't resist a bust-up.
0:12:35 > 0:12:37And greenfinches are even worse.
0:12:37 > 0:12:40You'd think they spend their time eating instead of fighting.
0:12:47 > 0:12:50But no-one stands their ground like a nuthatch.
0:13:07 > 0:13:12We spend £365 million a year feeding birds.
0:13:14 > 0:13:17For these few weeks, that becomes a lifeline.
0:13:26 > 0:13:29The frost spreads its fingers into the earth itself,
0:13:29 > 0:13:34and that makes life hard for our most famous winter bird.
0:13:34 > 0:13:39Robins tend to feed on worms and insects buried underground,
0:13:39 > 0:13:42but now that ground is frozen solid.
0:13:44 > 0:13:46Luckily, help is at hand.
0:13:47 > 0:13:49Moles.
0:13:51 > 0:13:55Their molehills are chock full of worms and edible insect larvae.
0:14:00 > 0:14:04Every fresh molehill becomes a feeding opportunity.
0:14:12 > 0:14:15If you ever wondered why robins follow you around
0:14:15 > 0:14:18when you dig your garden in winter, now you know.
0:14:32 > 0:14:36It may be bitterly cold, but for gardeners and farmers alike,
0:14:36 > 0:14:39winter is still the best time for turning the soil
0:14:39 > 0:14:41and preparing for the year ahead.
0:14:45 > 0:14:48In Oxfordshire, it's a perfect day for ploughing.
0:14:52 > 0:14:56With each pass, the plough does the work of many millions of moles,
0:14:56 > 0:14:58turning over tons of soil.
0:14:59 > 0:15:02If ever there was an opportunity
0:15:02 > 0:15:06to get at the bugs beneath the frozen soil, this is it.
0:15:21 > 0:15:25Recently, winter ploughing here has started attracting new visitors.
0:15:27 > 0:15:29Red kites.
0:15:32 > 0:15:34They were almost extinct only 100 winters ago,
0:15:34 > 0:15:37yet now their numbers are booming.
0:15:41 > 0:15:44The kite's natural ability to swoop and grab carrion
0:15:44 > 0:15:48has been adapted to "dive bombing" this plough.
0:15:54 > 0:15:58They adjust and trim their flight to come in low,
0:15:58 > 0:16:00right behind the blades.
0:16:05 > 0:16:08Sometimes they catch the worms without even touching down.
0:16:20 > 0:16:23The farmer's skill at ploughing the perfect furrow
0:16:23 > 0:16:27is more than matched by the aerobatic skill of these kites.
0:16:56 > 0:16:58Without this human activity,
0:16:58 > 0:17:01kites might struggle to make it through winter
0:17:01 > 0:17:04and might well be back on the brink of extinction.
0:17:17 > 0:17:18Britain's winter landscape
0:17:18 > 0:17:23is characterised by the stark skeletons of our native trees.
0:17:23 > 0:17:29There is one rather surprising result to having leafless branches.
0:17:29 > 0:17:33In the summer, the tree trunks are shaded by the leafy canopy.
0:17:33 > 0:17:37But six months on, the trunks are bathed in sunshine
0:17:37 > 0:17:41and become the perfect surface for a unique winter crop.
0:17:41 > 0:17:45That crop is edible green algae.
0:17:53 > 0:17:55At first glance, there's nothing around to eat it,
0:17:55 > 0:18:00but come a warm blip in the cold weather, and that all changes.
0:18:09 > 0:18:13From the gloom, come countless crustaceans.
0:18:13 > 0:18:17The same woodlice we find in our garden.
0:18:30 > 0:18:33On these rare nights - brief windows of opportunity -
0:18:33 > 0:18:38billions of these tiny creatures are grazing in our woodlands.
0:18:43 > 0:18:47As soon as the cold returns, they melt back into the night.
0:19:06 > 0:19:09One of the greatest joys of a British winter
0:19:09 > 0:19:11is waking up to a completely different world.
0:19:52 > 0:19:56As the giant, white duvet covers the landscape,
0:19:56 > 0:19:58it isn't just the sights that change.
0:19:58 > 0:20:01Hard edges are cushioned, and echoes are muffled,
0:20:01 > 0:20:04giving us the sound of winter.
0:20:19 > 0:20:24The sun's rays are now being reflected, making it colder still.
0:20:38 > 0:20:41To the north and on higher ground,
0:20:41 > 0:20:43what was already a challenging place to live
0:20:43 > 0:20:45has just become even more so.
0:20:50 > 0:20:54Hardy Cumbrian sheep can no longer find food for themselves
0:20:54 > 0:20:57and must rely on the farmer until the snow melts.
0:21:04 > 0:21:06Further north still,
0:21:06 > 0:21:10the Scottish Highlands have become Britain's most extreme environment.
0:21:16 > 0:21:19The animals here are defined by their ability
0:21:19 > 0:21:22to survive these few unforgiving weeks in the year.
0:21:34 > 0:21:37For us, just to visit the highlands requires special equipment,
0:21:37 > 0:21:41and even then, we can't stay outside for long.
0:21:42 > 0:21:46Each year, the elements kill about 20 people on these mountains.
0:21:49 > 0:21:53In southern, low-lying areas, snow is rather more of a novelty...
0:21:55 > 0:21:57..so we tend to make the most of it.
0:21:59 > 0:22:02# Sun is shining in the sky
0:22:02 > 0:22:05# There ain't a cloud in sight
0:22:05 > 0:22:09# It's stopped raining Everybody's in a play... #
0:22:09 > 0:22:11The bird tables are busy.
0:22:11 > 0:22:14The birds will be OK as long as the food keeps coming.
0:22:16 > 0:22:18# Running down the avenue
0:22:18 > 0:22:22# See how the sun shines brightly
0:22:22 > 0:22:26# In the city On the streets where once was pity
0:22:26 > 0:22:32# Mr Blue Sky is living here today Hey-hey-hey
0:22:32 > 0:22:35# Mr Blue Sky, please tell us why
0:22:35 > 0:22:40# You had to hide away for so long So long
0:22:40 > 0:22:44# Where did we go wrong?
0:22:44 > 0:22:47# Mr Blue Sky, please tell us why
0:22:47 > 0:22:51# You had to hide away for so long So long
0:22:51 > 0:22:53# Where did we go wrong? #
0:22:53 > 0:22:57Enjoying the winter wonderland is all part of being British.
0:23:01 > 0:23:06But then when we've had enough, we can go in for a nice hot cup of tea.
0:23:13 > 0:23:16The snow isn't putting off these brown hares.
0:23:24 > 0:23:26These young males are hoping to find a mate
0:23:26 > 0:23:28and have stated boxing early.
0:23:37 > 0:23:39In fact, these famous bouts
0:23:39 > 0:23:43are often a female beating up an over-eager young male.
0:23:59 > 0:24:01If he isn't strong enough to beat her,
0:24:01 > 0:24:03then she just isn't interested.
0:24:08 > 0:24:10Even on the odd occasion
0:24:10 > 0:24:12when the entire country is covered with snow,
0:24:12 > 0:24:17there is one place you can escape the freeze.
0:24:17 > 0:24:20The coast.
0:24:20 > 0:24:24Satellites measuring surface temperatures show that, in winter,
0:24:24 > 0:24:27the sea is much warmer than the land.
0:24:29 > 0:24:32This holds our winters in check
0:24:32 > 0:24:34and is part of what makes our seasons unique.
0:24:36 > 0:24:41Mind you, water draws heat out of us faster than air does,
0:24:41 > 0:24:46so a quick dip is still an achingly cold experience.
0:24:46 > 0:24:51This isn't usually a problem for Britain's largest wild resident.
0:24:52 > 0:24:57Grey seals are insulated by thick blubber and fur
0:25:02 > 0:25:07By February, the seals in Cornwall start to behave in a strange way.
0:25:11 > 0:25:14This is the time for their annual moult.
0:25:20 > 0:25:21They replace old fur,
0:25:21 > 0:25:26and to do that they must pump blood closer to their skin's surface.
0:25:26 > 0:25:29So now they feel the cold.
0:25:29 > 0:25:33It's no surprise the water is less inviting.
0:25:46 > 0:25:50The incoming tide makes them behave less like seals
0:25:50 > 0:25:54and more like nervous holidaymakers.
0:26:13 > 0:26:15We may be a small island,
0:26:15 > 0:26:18but our crinkly coastline is nearly 12,000 miles long.
0:26:20 > 0:26:24And with the help of the warming effect of the sea,
0:26:24 > 0:26:28there are a few special places, where in winter,
0:26:28 > 0:26:31life gathers on a massive scale.
0:26:33 > 0:26:36This is the Wash estuary.
0:26:37 > 0:26:40Today is the biggest tide of the winter.
0:26:42 > 0:26:48As the water drops, it exposes miles of mud full of life.
0:26:48 > 0:26:53Billions of creatures, living just below the surface.
0:26:57 > 0:27:00One type of bird makes a special effort
0:27:00 > 0:27:02to come here to feed in our winter.
0:27:02 > 0:27:04Huge numbers of arctic knot
0:27:04 > 0:27:09have been arriving here every day since November.
0:27:20 > 0:27:22They have now reached their peak,
0:27:22 > 0:27:24at around 100,000.
0:27:28 > 0:27:32The race begins as they rush to feed on the exposed mud.
0:27:40 > 0:27:43As the water rises and falls,
0:27:43 > 0:27:48the shape of the feeding grounds is constantly shifting.
0:28:13 > 0:28:17This display is one of the winter season's secrets.
0:28:17 > 0:28:20Few of us are lucky enough to see it.
0:28:23 > 0:28:26By mid-February, winter should be passing its peak,
0:28:26 > 0:28:28but this year it's still cold
0:28:28 > 0:28:31and inland the snow still covers the ground.
0:28:36 > 0:28:38Under a blanket of white in a Gloucestershire wood,
0:28:38 > 0:28:42a delicate flower is just about to make its move.
0:28:55 > 0:28:58This is the time of the snowdrop.
0:29:01 > 0:29:04They are not the tallest, not the most colourful,
0:29:04 > 0:29:08but they have stolen the race on practically everything else.
0:29:10 > 0:29:13Their timing is perfect.
0:29:15 > 0:29:17Without any other plants to blot out the sun,
0:29:17 > 0:29:20each tiny snowdrop is free to harvest the light.
0:29:29 > 0:29:33For most of us, it's our first sight of a wild flower for months,
0:29:33 > 0:29:35and even a symbol of hope.
0:29:59 > 0:30:02It's St Valentine's day.
0:30:02 > 0:30:06In Norfolk, a pond has begun to thaw.
0:30:13 > 0:30:17For a male frog, it's time to act..
0:30:22 > 0:30:26Amazingly, it's the smell of growing algae that's brought him here.
0:30:31 > 0:30:33And the boys call in the girls.
0:30:43 > 0:30:47The orgy of frogs spawn now
0:30:47 > 0:30:50so that their babies might feed on the algae
0:30:50 > 0:30:52when it blooms in a few weeks' time.
0:31:02 > 0:31:07A few hours of winter sun draws adders out onto a heath in Kent.
0:31:14 > 0:31:16To catch the most rays,
0:31:16 > 0:31:19these males are able to flatten their bodies.
0:31:23 > 0:31:28He and other male adders need this warmth to speed up sperm production.
0:31:31 > 0:31:33They won't mate till spring,
0:31:33 > 0:31:36but they're making hay while the sun shines.
0:31:47 > 0:31:50In Cumbria, the red squirrels have made it this far
0:31:50 > 0:31:53on food they stored back in autumn.
0:31:55 > 0:32:00And these nuts are all the food they have until the spring arrives.
0:32:08 > 0:32:12Whether they make it now will all be down to cunning.
0:32:22 > 0:32:28There's much more to squirreling away than just simply burying nuts.
0:32:28 > 0:32:31There's a strategy.
0:32:31 > 0:32:36If this red squirrel finds more food than she can immediately deal with,
0:32:36 > 0:32:39she'll hide it again somewhere else.
0:32:43 > 0:32:44It's a great system.
0:32:44 > 0:32:48The problem is that there are lots of squirrels around
0:32:48 > 0:32:51and every time she digs up a nut, their eyes are on her.
0:33:06 > 0:33:12She knows they are watching, and they know she knows.
0:33:17 > 0:33:19So, she changes her game.
0:33:19 > 0:33:22If she goes to hide a nut, but spots she's being watched,
0:33:22 > 0:33:24she moves on.
0:33:35 > 0:33:37If she's fast with her paws,
0:33:37 > 0:33:40she can trick them into thinking that she's buried it...
0:33:43 > 0:33:44..when she hasn't.
0:33:44 > 0:33:47And so, the game continues.
0:33:47 > 0:33:50Leading them on a merry chase of deception.
0:33:50 > 0:33:56For the spying squirrels, it's worth checking everywhere she's been,
0:33:56 > 0:33:59just in case it was a double bluff.
0:34:03 > 0:34:06For our heroine, being sneaky is the only way to survive.
0:34:09 > 0:34:12Save your food today because you're never quite sure
0:34:12 > 0:34:16how long the tough times will last.
0:34:25 > 0:34:30You can't take anything for granted in a British Winter.
0:34:30 > 0:34:32Back at the old aerodrome in Essex,
0:34:32 > 0:34:35there is a hopeful hint of sunshine breaking through.
0:34:40 > 0:34:45The good news is that the barn owls have made it this far.
0:34:47 > 0:34:50And the kestrel's doing OK too.
0:34:50 > 0:34:53They're not alone though.
0:34:53 > 0:34:56Little owls are living in a tree overlooking the old barracks.
0:34:58 > 0:35:00Just across the old airstrip,
0:35:00 > 0:35:04two rare, long-eared owls sit silently where planes used to roar.
0:35:06 > 0:35:10The locals birds have even been joined by a visitor -
0:35:10 > 0:35:11a short-eared owl.
0:35:19 > 0:35:22Her yellow eyes mark her out as a day hunter.
0:35:27 > 0:35:31There are so many owls here, because even in winter,
0:35:31 > 0:35:33the land is teeming with mice and voles.
0:36:36 > 0:36:38The hares are still frisky.
0:36:55 > 0:36:56Some have already got babies.
0:36:56 > 0:36:59Right now, they're hidden in the grass somewhere nearby.
0:37:04 > 0:37:07During daylight, the aerodrome holds few dangers for them.
0:37:13 > 0:37:16As night falls, all that will change.
0:37:23 > 0:37:27A thermal camera allows us to see what's going on.
0:37:27 > 0:37:30There are no lights at all.
0:37:30 > 0:37:32It's completely dark.
0:37:34 > 0:37:39And yet, the camera detects tiny differences in temperature.
0:37:39 > 0:37:42It can see individual stems of grass,
0:37:42 > 0:37:45and the brickwork on the old barracks.
0:37:45 > 0:37:49Anything warm stands out as black.
0:37:49 > 0:37:53This is a mother hare.
0:37:55 > 0:37:57She's nervous...
0:37:57 > 0:38:00and this is why.
0:38:00 > 0:38:04The faint glow in the grass is her hidden baby -
0:38:04 > 0:38:08a leveret - just a day or two old.
0:38:09 > 0:38:11Mum can hardly see in the dark,
0:38:11 > 0:38:15but she can smell and hear what's going on around her.
0:38:23 > 0:38:26Every faint rustle catches her attention.
0:38:29 > 0:38:32Meanwhile, her cousins, the neighbourhood rabbits,
0:38:32 > 0:38:34turn to a spot of urine-spraying -
0:38:34 > 0:38:38all part of their unique mating ritual.
0:38:42 > 0:38:46She can't be sure which sound means danger.
0:38:47 > 0:38:51That's the lolloping gait of a badger.
0:38:52 > 0:38:54The mother hare has no idea it's there.
0:38:57 > 0:39:00It's digging for worms at the moment,
0:39:00 > 0:39:04but if it finds the baby hare, it will eat it in a second.
0:39:09 > 0:39:11The badger's heading their way.
0:39:11 > 0:39:15A few more metres, and it could pick up the baby's scent.
0:39:25 > 0:39:27A piercing cry gets everyone's attention.
0:39:27 > 0:39:29PIERCING CRY
0:39:33 > 0:39:35A fox.
0:39:35 > 0:39:39It's heading in their direction.
0:40:02 > 0:40:07Suddenly, both fox and badger catch each other's scent.
0:40:15 > 0:40:18The fox turns tail - it spooks everyone.
0:40:41 > 0:40:45The leveret is safe, for tonight.
0:40:59 > 0:41:03There is no single moment when winter finally loosens its grip.
0:41:03 > 0:41:08It's the nature of Britain that deep snow can cover one county
0:41:08 > 0:41:11and yet it's mild just a few miles away.
0:41:16 > 0:41:18Whatever the weather is doing,
0:41:18 > 0:41:22the days are getting longer and nature is reacting.
0:41:24 > 0:41:29Inside the trees, their cells are changing, preparing for the future.
0:41:32 > 0:41:35The north of our planet is slowly tilting back towards the sun.
0:41:35 > 0:41:40Britain is warming.
0:42:36 > 0:42:40It seems, for the last few months, wildlife here in Britain
0:42:40 > 0:42:43has been barely clinging on,
0:42:43 > 0:42:45but we can all feel a change.
0:42:45 > 0:42:48It's is not just about survival any more,
0:42:48 > 0:42:49it's about new life.
0:42:54 > 0:42:56These are catkins -
0:42:56 > 0:43:00special flowers adapted to catch the breeze and scatter pollen.
0:43:02 > 0:43:05This is easier before the leaves have grown back on the trees.
0:43:15 > 0:43:18The slightest breath of wind or nudge of a passing bird
0:43:18 > 0:43:20is all that's needed.
0:43:43 > 0:43:46As the pollen lands on the red female flower,
0:43:46 > 0:43:48life begins.
0:43:53 > 0:43:56By March, Britain is straddling two seasons
0:43:56 > 0:43:59and in the countryside, things are picking up pace.
0:44:02 > 0:44:05Here in Somerset, it's time for hedge laying,
0:44:05 > 0:44:08just as it's been done for hundreds of years.
0:44:11 > 0:44:13When this lattice of branches sprouts,
0:44:13 > 0:44:16it will create a new strong field boundary,
0:44:16 > 0:44:20and one of the country's most important wild habitats.
0:44:24 > 0:44:28The magic ingredient is the rising temperature.
0:44:30 > 0:44:35At it passes seven degrees, our plants begin to grow in earnest
0:44:35 > 0:44:39and it's particularly true for Britain's biggest crop, grass.
0:44:39 > 0:44:43It covers over half of the entire UK landmass.
0:44:46 > 0:44:47The greening of Britain
0:44:47 > 0:44:51begins in our southern cities, with their millions of lawns.
0:44:55 > 0:44:57Time to get the mower out.
0:45:03 > 0:45:07Soon, all across the country,
0:45:07 > 0:45:10the newly sprouting grass will attract grazers.
0:45:22 > 0:45:23Here in north London,
0:45:23 > 0:45:26night-time visitors are already creeping into the suburbs
0:45:26 > 0:45:31to get to the first flush of new grass on our roadside verges.
0:45:38 > 0:45:41These are fallow deer.
0:45:41 > 0:45:43They live in nearby ancient woodlands
0:45:43 > 0:45:46and have been doing so for hundreds of years.
0:45:46 > 0:45:53Tonight, they're drawn out by the promise of richer pastures.
0:46:00 > 0:46:03The females are carrying young and in June they'll give birth.
0:46:03 > 0:46:07Every mouthful of grass they find is precious.
0:46:19 > 0:46:24Once they were hunted by Norman kings.
0:46:24 > 0:46:28Now, it's the cars they have to watch out for.
0:46:36 > 0:46:38In the passing of just a few days,
0:46:38 > 0:46:41it seems life has returned to our islands.
0:46:43 > 0:46:47Green shoots are emerging, animals venturing out,
0:46:47 > 0:46:50and Britain looks a completely different place.
0:46:51 > 0:46:53It's the spring equinox,
0:46:53 > 0:46:56when our days and nights are exactly the same length.
0:46:56 > 0:47:02The stage is set for the next big phase in the Great British Year.
0:47:32 > 0:47:36The 20th March, on a lake in Wiltshire.
0:47:36 > 0:47:39Two great crested grebes begin a magical dance
0:47:39 > 0:47:42that ushers in the next three months.
0:47:53 > 0:47:55There is courting to be done,
0:47:55 > 0:47:59territories to be established and nests to be built.
0:47:59 > 0:48:02Spring is finally here.
0:49:02 > 0:49:06To capture the broadest and most spectacular images
0:49:06 > 0:49:07of our changing islands
0:49:07 > 0:49:11demanded a novel approach to wildlife filmmaking.
0:49:11 > 0:49:14An army of photographers,
0:49:14 > 0:49:18more than have ever been used in a British wildlife series,
0:49:18 > 0:49:20were mobilised up and down the country.
0:49:21 > 0:49:26Cameramen with years of experience were joined by keen enthusiasts.
0:49:31 > 0:49:34By tapping into local knowledge and expertise,
0:49:34 > 0:49:38the team was able to gather footage of the country as it constantly changed,
0:49:38 > 0:49:41revealing the best, and the worst, of the British weather.
0:49:51 > 0:49:53The team also turned to new techniques
0:49:53 > 0:49:56when they focused their cameras on the wildlife itself.
0:49:59 > 0:50:03Stowe Maries - a disused World War I airfield.
0:50:06 > 0:50:10It's known for having an amazing concentration of birds of prey
0:50:10 > 0:50:12and is home to dozens of hares.
0:50:12 > 0:50:18But the team suspected there was more to this place.
0:50:18 > 0:50:21To unlock its secrets, they decided to film at night.
0:50:38 > 0:50:39This Pinzgauer vehicle
0:50:39 > 0:50:43is equipped with the world's most advanced thermal imaging cameras.
0:50:43 > 0:50:49On top of a mast, the camera can survey the surrounding countryside.
0:50:49 > 0:50:53It's used by the military in night surveillance -
0:50:53 > 0:50:56the precise details are all a bit hush-hush.
0:50:58 > 0:51:00Cameraman Lindsay McCrae
0:51:00 > 0:51:04was getting a crash course in covert surveillance techniques.
0:51:05 > 0:51:09The plan was for Lindsay to use another, portable version of the camera
0:51:09 > 0:51:11so he could get as close as possible to the animals.
0:51:18 > 0:51:21As night fell, the main crew retired to the Pinzgauer.
0:51:23 > 0:51:26This was a whole new experience for the team.
0:51:26 > 0:51:28Thermal cameras form a picture
0:51:28 > 0:51:30by sensing heat without needing any lights.
0:51:30 > 0:51:35So your subjects have no idea they are being filmed.
0:51:35 > 0:51:37# Freak out!
0:51:37 > 0:51:39# Le freak, c'est chic
0:51:39 > 0:51:41# Freak out! #
0:51:42 > 0:51:44# Ah, freak out!
0:51:44 > 0:51:47# Le freak, c'est chic
0:51:47 > 0:51:49# Freak out! #
0:51:49 > 0:51:53It clearly worked on the team. Would it work on the wildlife?
0:51:54 > 0:51:58James Brickell had the job of co-ordinating operations.
0:51:58 > 0:52:01We've got an area the size of ten rugby pitches.
0:52:01 > 0:52:04We can't see all of it at once,
0:52:04 > 0:52:06so by having two cameras up high
0:52:06 > 0:52:10we can look down on the area with the thermal cameras here
0:52:10 > 0:52:13and then direct Lindsay on the ground.
0:52:13 > 0:52:15We're being spotters, basically.
0:52:15 > 0:52:19My job was essentially to be Lindsay's eyes and ears.
0:52:19 > 0:52:24The important thing about this camera is that anything with body heat stands out,
0:52:24 > 0:52:26so it's not just about filming them,
0:52:26 > 0:52:29you can actually find them in the first place -
0:52:29 > 0:52:32more easily than if you were filming during the day.
0:52:34 > 0:52:39You still need field-craft though, because Lindsay needed to stay quiet,
0:52:39 > 0:52:43to stay down wind, to put himself in the right position
0:52:43 > 0:52:45to get the very best shots.
0:52:50 > 0:52:54Filming like this put us right in the middle of the action
0:52:54 > 0:52:56with Lindsay just metres away from what was happening,
0:52:56 > 0:52:58and we were seeing stuff
0:52:58 > 0:53:00that would usually be so camouflaged you wouldn't spot it.
0:53:06 > 0:53:08I think that's a woodcock.
0:53:08 > 0:53:11We're at the end of our zoom.
0:53:11 > 0:53:14It's not bad, it's brilliant. That's a woodcock.
0:53:14 > 0:53:17They are impossible to see in the day.
0:53:18 > 0:53:22Hello Linds, if you can hear me, there's a muntjac deer -
0:53:22 > 0:53:25I think it's a deer - on the bank on the other side.
0:53:30 > 0:53:31For over 100 years,
0:53:31 > 0:53:34the airfield has not had much farming that I know.
0:53:34 > 0:53:39It's had no pesticides, no spraying, no hunting.
0:53:39 > 0:53:40It's not really surprising,
0:53:40 > 0:53:44I saw more British mammals in one night than I'd ever seen before.
0:53:45 > 0:53:48One of the challenges of this camera
0:53:48 > 0:53:53is that the thermal outline of an animal may be different from its actual outline.
0:53:53 > 0:53:58It's quite hard to identify exactly what you're looking at.
0:53:58 > 0:54:04The stars were the hares, the adults are great animals, great characters,
0:54:04 > 0:54:08but then with this camera, it helped us find the babies.
0:54:08 > 0:54:10There's Lindsay, our cameraman,
0:54:10 > 0:54:15and he's filming some leverets, baby hares that are about -
0:54:15 > 0:54:20it's difficult to tell - 20 metres in front of him? They are so cute.
0:54:20 > 0:54:22We went looking for them in the day
0:54:22 > 0:54:27and we walked straight over the spot where they were, four or five times,
0:54:27 > 0:54:28and didn't see them.
0:54:28 > 0:54:30So, without a thermal camera
0:54:30 > 0:54:33you would have no chance of spotting them at all.
0:54:35 > 0:54:37What's that? That's a badger.
0:54:39 > 0:54:42Linds, there's a badger right behind you, I think.
0:54:42 > 0:54:46Initially, I didn't think the badger would pose a threat
0:54:46 > 0:54:49because it looked like it was hunting for worms.
0:54:50 > 0:54:55In fact, we were all watching some bats that were circling it
0:54:55 > 0:54:58looking for insects it had kicked up,
0:54:58 > 0:55:01which is not something I've ever seen before.
0:55:04 > 0:55:06Suddenly, we realised the badger
0:55:06 > 0:55:11was heading straight right towards where the leverets were.
0:55:19 > 0:55:20Then, we got a bit of a surprise.
0:55:28 > 0:55:32I think that's... Is everyone else looking at this?
0:55:32 > 0:55:33That's not a hare, is it?
0:55:33 > 0:55:37Linds, I think there is a fox on the other side of the field.
0:55:37 > 0:55:42It is definitely a fox, mate. It's definitely a fox.
0:55:42 > 0:55:44Can you see it? Over.
0:55:44 > 0:55:48Fox is now on the left-hand side of the bank,
0:55:48 > 0:55:51still pretty close to the tree line,
0:55:51 > 0:55:53moving camera left and slightly away from you.
0:55:56 > 0:56:00How did we miss that? He must have come out right behind Lindsay.
0:56:00 > 0:56:04I think at this point - about eight hares, two leverets that we knew of,
0:56:04 > 0:56:06and now two predators, two hunters -
0:56:06 > 0:56:10a badger and a fox - all converging to the same spot.
0:56:10 > 0:56:13It looks like he's after a feed.
0:56:13 > 0:56:16I wonder if she finds your baby hares.
0:56:16 > 0:56:22It doesn't matter whether your filming sharks or lions in the wild, or badgers.
0:56:22 > 0:56:23You never get tired of it.
0:56:23 > 0:56:26There's always that sense of anticipation.
0:56:26 > 0:56:29You don't know what's going to happen next.
0:56:33 > 0:56:35He's turned towards us.
0:56:38 > 0:56:41That mum doesn't want to come closer, does she?
0:56:42 > 0:56:44He's coming out into the field.
0:56:44 > 0:56:48We could see everything that was going on with this camera.
0:56:48 > 0:56:53It was pitch dark, so the animals were relying on scent and sound.
0:56:55 > 0:56:58It's a long way away.
0:56:58 > 0:57:02Suddenly there was this stand-off. The fox seemed uneasy.
0:57:24 > 0:57:26Are you getting this?
0:57:26 > 0:57:28Whatever spooked them,
0:57:28 > 0:57:33it was a pretty lucky escape for the leveret, I think.
0:57:39 > 0:57:41Hidden by the dark, dramas like this
0:57:41 > 0:57:44play out all over the countryside every night.
0:57:44 > 0:57:47It was only by using this new camera that it was possible
0:57:47 > 0:57:50to witness Britain's secret wildlife in this way.
0:57:57 > 0:58:00It's just one of the many techniques the team would use
0:58:00 > 0:58:03to reveal the story of our changing land.
0:58:03 > 0:58:09To get a free copy of this poster about British seasons,
0:58:09 > 0:58:13call 0845 271 0017
0:58:13 > 0:58:17or go to bbc.co.uk/greatbritishyear
0:58:17 > 0:58:19Follow the links to the Open University
0:58:19 > 0:58:22and take part in our seasonal wildlife census.