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0:00:04 > 0:00:06- A land of extremes.
0:00:07 > 0:00:11- Where fire and ice clash.
0:00:15 > 0:00:19- Ancient mountains - give way to lush forests.
0:00:19 > 0:00:23- A forgotten wilderness...
0:00:23 > 0:00:26- ..dazzling in its diversity.
0:00:26 > 0:00:30- Seasons of darkness - and perpetual light...
0:00:31 > 0:00:34- ..reveal life - thriving against all odds.
0:00:38 > 0:00:41- In a place this brutal...
0:00:41 > 0:00:44- ..every creature - must expect the unexpected.
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0:01:10 > 0:01:13- Life in Scandinavia - is full of danger.
0:01:13 > 0:01:19- Differences in temperature between - winter and summer are extreme.
0:01:25 > 0:01:29- The land itself - is unpredictable and unstable.
0:01:32 > 0:01:35- It's a region of Arctic cold...
0:01:35 > 0:01:38- ..and rock-melting heat.
0:01:47 > 0:01:52- But life has developed extraordinary - strategies for survival.
0:01:52 > 0:01:55- The earth's raw power and beauty - go hand in hand.
0:02:05 > 0:02:08- The extreme chill - has a tight grip on the land.
0:02:11 > 0:02:15- In the highlands of northern - Iceland, temperatures can plummet...
0:02:15 > 0:02:17- ..to minus-39 degrees Celsius.
0:02:25 > 0:02:27- The Arctic fox braves the chill.
0:02:34 > 0:02:37- It's about the same size - as a domestic cat...
0:02:37 > 0:02:41- ..but its thick coat - makes it look much bigger.
0:02:45 > 0:02:49- A stubby nose and short ears - enables it to conserve heat...
0:02:49 > 0:02:53- ..as does its amazing ability - to reduce blood flow...
0:02:54 > 0:02:56- ..to the body's exposed areas.
0:02:58 > 0:03:00- But the real secret is its fur...
0:03:00 > 0:03:05- ..which covers its entire body, - including the soles of its feet.
0:03:10 > 0:03:14- In winter, - the fox's fur trebles in length...
0:03:14 > 0:03:18- ..giving it the warmest coat - in the animal kingdom.
0:03:22 > 0:03:27- It can survive weather that would - kill most mammals within minutes.
0:03:39 > 0:03:43- If the weather worsens, the fox can - just curl up into a furry ball...
0:03:44 > 0:03:46- ..and wait - for conditions to improve.
0:03:50 > 0:03:54- The northernmost reaches - of the Arctic Circle...
0:03:54 > 0:03:56- ..bear the harshest winters.
0:03:58 > 0:04:00- This area is vast.
0:04:08 > 0:04:12- Spanning the globe from the - frozen shores of North America...
0:04:12 > 0:04:14- ..to the Russian border...
0:04:14 > 0:04:17- ..comprising of five countries...
0:04:17 > 0:04:21- ..and nearly 100,000km of coastline - make up Scandinavia.
0:04:24 > 0:04:28- Over the millennia, - the landscape has been squeezed...
0:04:28 > 0:04:34- ..by colossal corridors of ice - and collisions of the earth's crust.
0:04:39 > 0:04:43- In Iceland, - the landscape itself is unstable.
0:04:43 > 0:04:48- Where underground waterways - meet lava floes...
0:04:48 > 0:04:53- ..boiling water turns to steam - and explodes from the ground.
0:05:11 > 0:05:16- 500 kilometres west, lands formed - hundreds of millions of years ago...
0:05:16 > 0:05:20- ..are home to creatures - that have changed very little...
0:05:20 > 0:05:22- ..since prehistoric times.
0:05:22 > 0:05:28- Scandinavia's tallest peaks are - found on the earth's largest island.
0:05:30 > 0:05:35- Greenland, where some of the - world's most experienced climbers...
0:05:35 > 0:05:37- ..are heading to its peaks.
0:05:39 > 0:05:43- Musk oxen - are made for the mountains.
0:05:45 > 0:05:49- They can tolerate wind chills - of minus-60 degrees...
0:05:49 > 0:05:55- ..due to a soft brown fleece, - several times warmer than wool.
0:06:04 > 0:06:09- Their winter coats allow them to - adopt an unusual survival strategy.
0:06:10 > 0:06:13- Instead of taking cover - in high winds...
0:06:14 > 0:06:17- ..they spend - much of the winter on high ground.
0:06:20 > 0:06:23- Up here, driving winds - blow away most of the snow...
0:06:24 > 0:06:28- ..making it easier for the musk ox - eat the grass underneath.
0:06:31 > 0:06:37- They produce just enough energy - to keep them moving and keep warm.
0:06:41 > 0:06:45- Only exceptional animals - can survive in these parts.
0:06:48 > 0:06:51- On the low plains of Iceland...
0:06:51 > 0:06:54- ..a remote huddle - of more recent immigrants emerge.
0:07:02 > 0:07:05- The Icelandic horse - has a turbulent past.
0:07:08 > 0:07:12- These animals' ancestors - were brought here...
0:07:12 > 0:07:15- ..by Vikings - more than 1,000 years ago.
0:07:21 > 0:07:25- They endure a climate - that would kill regular horses.
0:07:29 > 0:07:34- In a hundred generations, they have - developed into a unique breed.
0:07:34 > 0:07:38- They have adapted to - the harshest conditions on earth.
0:07:48 > 0:07:52- During these winter months, - days are short.
0:07:52 > 0:07:56- Fading daylight - forces temperatures even lower.
0:07:57 > 0:08:02- The darkening skies bear witness - to a very different storm.
0:08:12 > 0:08:14- To some Arctic peoples...
0:08:14 > 0:08:16- ..these Northern Lights...
0:08:16 > 0:08:20- ..are the spirits of dead seals, - whales and caribou.
0:08:22 > 0:08:27- But the Aurora Borealis is caused - by storms on the sun's surface.
0:08:27 > 0:08:30- Huge plasma flares - create solar winds...
0:08:30 > 0:08:34- ..that collide with our atmosphere.
0:08:35 > 0:08:37- These invisible energy streams...
0:08:37 > 0:08:41- ..get pushed towards - the South and North Poles.
0:08:41 > 0:08:45- The result is nature's - version of neon lights.
0:08:45 > 0:08:49- A single display can unleash - as much electrical power...
0:08:49 > 0:08:52- ..as the United States uses - in a single day.
0:08:59 > 0:09:04- Not many creatures are around - to witness this spectacle.
0:09:05 > 0:09:07- Because Iceland is so remote...
0:09:07 > 0:09:10- ..there are - very few animal species here.
0:09:12 > 0:09:14- Some birds have settled here...
0:09:14 > 0:09:18- ..and a few rodent species - imported by humans.
0:09:18 > 0:09:24- The only native land mammal - is the Arctic fox.
0:09:24 > 0:09:29- Its ancestors were stranded in - Iceland at the end of the Ice Age.
0:09:31 > 0:09:35- Calmer weather gives the fox - a chance to forage for food.
0:09:38 > 0:09:40- It's a resourceful hunter.
0:09:40 > 0:09:43- But winter means that good meals - are few and far between.
0:09:48 > 0:09:51- A rock ptarmigan - will make a tasty snack.
0:09:51 > 0:09:55- It's one of the few birds - to remain inland during winter.
0:09:57 > 0:10:00- Feathered feet act as snow shoes.
0:10:04 > 0:10:06- It's a master of disguise.
0:10:06 > 0:10:10- Pure white plumage makes it - all but invisible to the fox.
0:10:10 > 0:10:13- Come spring, when the snow melts...
0:10:13 > 0:10:17- ..it will change - to a mottled brown colour.
0:10:19 > 0:10:24- On the mainland, most Arctic foxes - also grow pure white winter coats...
0:10:24 > 0:10:28- ..but this remote island's - population is different.
0:10:31 > 0:10:36- With no natural predators, there's - little need for winter camouflage.
0:10:36 > 0:10:41- This is why most foxes here retain - their dark colour all year long.
0:10:43 > 0:10:47- But dark coats - make them visible in the snow.
0:10:50 > 0:10:53- So the ptarmigan - has plenty of warning.
0:10:57 > 0:11:00- With so little prey available...
0:11:00 > 0:11:04- ..starvation is a perpetual threat - for the Arctic fox.
0:11:07 > 0:11:11- It often buries leftovers - in case of emergency.
0:11:14 > 0:11:18- But finding its stash - after a snowstorm is very difficult.
0:11:32 > 0:11:35- Persistence finally pays off.
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0:11:52 > 0:11:54- Iceland is home to...
0:11:54 > 0:11:59- ..one of the greatest concentrations - of volcanoes in the world.
0:11:59 > 0:12:04- Major eruptions occur here - every five years on average.
0:12:06 > 0:12:09- Deep underground, - things are beginning to stir.
0:12:15 > 0:12:17- Small earthquakes are more frequent.
0:12:17 > 0:12:20- The mountains - are starting to awaken.
0:12:27 > 0:12:33- 2,000km east, a very different - landscape provides refuge.
0:12:38 > 0:12:40- Finland's vast woodlands...
0:12:40 > 0:12:43- ..offer shelter and food - for a variety of wildlife.
0:12:56 > 0:12:59- The red fox - thrives amongst the trees.
0:13:01 > 0:13:05- Just as in Iceland, - hidden stashes of food...
0:13:06 > 0:13:09- ..make all the difference - between life and death.
0:13:18 > 0:13:21- For many predators, - small mammals like lemmings...
0:13:22 > 0:13:24- ..are an important food source.
0:13:28 > 0:13:31- The lemming - relies on the snow to hide.
0:13:31 > 0:13:35- His cosy underground den - is lined with leaves and feathers.
0:13:35 > 0:13:38- Hibernation isn't essential.
0:13:39 > 0:13:44- But with predators all around, life - for smaller creatures is perilous.
0:13:45 > 0:13:49- It's best not to spend - too much time out in the open.
0:13:55 > 0:13:58- The hawk owl's beady eye - sees everything.
0:14:15 > 0:14:18- Next time it may not be so lucky.
0:14:30 > 0:14:33- The Eurasian lynx - also has his eye on the lemming.
0:14:41 > 0:14:43- Extremely rare and secretive...
0:14:44 > 0:14:49- ..the lynx inhabits high forests - all across the northern hemisphere.
0:14:49 > 0:14:53- It's a confident tree climber - and can even swim...
0:14:53 > 0:14:57- ..although in this bitter season, - water is best avoided.
0:15:01 > 0:15:03- A raven could be an easy target...
0:15:04 > 0:15:06- ..if the lynx - can just get close enough.
0:15:32 > 0:15:35- Some things are best left alone.
0:15:35 > 0:15:39- The lynx has more of a problem - to contend with.
0:15:43 > 0:15:45- Competition.
0:15:49 > 0:15:52- The forest is home to the wolverine.
0:16:00 > 0:16:03- It's a close relation to the weasel.
0:16:09 > 0:16:12- Though it has - an innocent, cuddly appearance...
0:16:12 > 0:16:15- ..the wolverine - is a ferocious animal.
0:16:22 > 0:16:26- Weighing up to 20 kilos, - it has boundless energy.
0:16:27 > 0:16:31- It marks its territory carefully.
0:16:33 > 0:16:38- Its potential prey is any animal - that wanders into its territory.
0:16:42 > 0:16:46- Anything from rabbits and birds - to reindeer and elk are fair game.
0:16:57 > 0:17:01- Ravens have a good chance of a meal - when a wolverine is nearby.
0:17:12 > 0:17:17- Casualties of the cold provide a - ready supply of food for any hunter.
0:17:20 > 0:17:23- The wolverine - will never share its prize.
0:17:28 > 0:17:32- The lynx is deep inside - the wolverine's territory.
0:17:33 > 0:17:36- It keeps a respectful distance.
0:17:49 > 0:17:52- The lynx watches, biding its time.
0:17:53 > 0:17:55- There's no rush.
0:18:09 > 0:18:13- The fading light - prompts the lynx to make its move.
0:18:21 > 0:18:25- The wolverine - is usually nocturnal...
0:18:25 > 0:18:31- ..but during winter nights, it hunts - and sleeps in four-hour shifts.
0:18:33 > 0:18:37- It checks its larder - one more time and leaves.
0:18:42 > 0:18:45- For the lynx, it's an easy steal.
0:19:09 > 0:19:13- In more southerly regions, - snow and ice slowly melt...
0:19:13 > 0:19:15- ..in the March sun.
0:19:17 > 0:19:19- The prospect of warmer weather...
0:19:20 > 0:19:24- ..heralds an influx of - Scandinavia's part-time residents.
0:19:24 > 0:19:30- Northernmost countries provide a - home to millions of migratory birds.
0:19:31 > 0:19:34- But migration patterns are changing.
0:19:34 > 0:19:38- Global warming is altering - the timing of the seasons.
0:19:40 > 0:19:44- Birds seem to be adapting. They - arrive slightly earlier each year.
0:19:57 > 0:20:00- In Iceland, thousands - of black-legged kittiwakes...
0:20:01 > 0:20:03- ..descend upon - the Hornstrandir cliffs.
0:20:08 > 0:20:12- Precarious perches are constructed - from seaweed and grass...
0:20:12 > 0:20:14- ..and glued to rocks with saliva.
0:20:19 > 0:20:21- Pairs often reunite annually.
0:20:24 > 0:20:27- They take turns in guarding eggs...
0:20:27 > 0:20:29- ..and hunting for small fish.
0:20:37 > 0:20:42- A long-legged traveller lands in - the Swedish wetlands - the crane.
0:20:42 > 0:20:45- From their winter vacation - in East Africa...
0:20:45 > 0:20:50- ..they've journeyed across the - Middle East and eastern Europe...
0:20:50 > 0:20:55- ..to reach this spot, covering - a distance of more than 7,000km.
0:20:55 > 0:20:58- The long journey - leads to short tempers.
0:21:03 > 0:21:05- RAUCOUS SQUAWKING
0:21:10 > 0:21:14- They soon get down - to the serious business of mating.
0:21:19 > 0:21:23- Synchronised honking and strutting - bring them together.
0:21:31 > 0:21:34- The female yields - by opening her wings.
0:21:54 > 0:21:58- It's a ritual that has lasted - for thousands of years.
0:22:05 > 0:22:09- Nearby, flowing water - is a lifeline for some creatures.
0:22:17 > 0:22:20- The otter and the dipper - rely on streams and rivers...
0:22:20 > 0:22:22- ..for their food supply.
0:22:35 > 0:22:38- The otter's sleek outer coat - is of fine hair...
0:22:38 > 0:22:40- ..covered in oil.
0:22:40 > 0:22:44- The hairs lie flat - during swimming...
0:22:44 > 0:22:47- ..trapping - an insulating layer of air...
0:22:47 > 0:22:50- ..and keeping - the inner fur and skin dry.
0:22:52 > 0:22:55- The dipper - uses a different method to stay dry.
0:22:57 > 0:23:01- By splashing around, the tiny bird - coats its feathers with oil.
0:23:08 > 0:23:10- It can see underwater.
0:23:25 > 0:23:29- A quick glance beneath the surface - and the dipper spots its target.
0:23:29 > 0:23:31- It takes the plunge.
0:23:34 > 0:23:37- Crustaceans and larvae - are sources of protein.
0:23:41 > 0:23:47- The Eurasian otter's high metabolism - calls for a heftier diet.
0:23:48 > 0:23:52- It must eat up to 15% - of its bodyweight every day.
0:23:54 > 0:23:58- The cold makes - fish and crayfish easy pickings.
0:23:58 > 0:24:01- If things get scarce underwater...
0:24:01 > 0:24:05- ..then rodents - and even birds are on the menu.
0:24:14 > 0:24:17- Life is far from easy - for the crane in Sweden.
0:24:22 > 0:24:27- The birds arrived early, but - the weather is so unpredictable...
0:24:27 > 0:24:29- ..this year's spring is late.
0:24:32 > 0:24:35- They are - laying their eggs on time...
0:24:35 > 0:24:37- ..but it's still far too cold.
0:24:41 > 0:24:44- In these freezing temperatures...
0:24:44 > 0:24:47- ..the eggs - have no chance of hatching.
0:24:48 > 0:24:51- Despite the crane's best efforts, - its work is in vain.
0:25:03 > 0:25:05- The survival of these birds...
0:25:05 > 0:25:10- ..may depend on their ability - to adapt to their changing world.
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0:25:24 > 0:25:30- Iceland's Eyjafjallajokull volcano - has exploded into life...
0:25:31 > 0:25:36- ..hurling 750 tons of pulverised - rock into the air every second.
0:25:48 > 0:25:52- The two sections of the earth's - crust on which it sits...
0:25:53 > 0:25:58- ..are slowly separating, releasing - magma and steam from deep within.
0:26:13 > 0:26:17- Pulverised rock - scorches everything in its wake.
0:26:21 > 0:26:23- Vegetation is suffocated.
0:26:27 > 0:26:31- The dense ash cloud blocks sunlight - for hundreds of kilometres...
0:26:32 > 0:26:35- ..and brings Europe's - air traffic to a standstill.
0:26:38 > 0:26:42- Iceland is, quite literally, - being torn apart.
0:26:45 > 0:26:47- It resembles - the surface of the moon.
0:27:05 > 0:27:09- For animals living - in the shadow of the volcano...
0:27:09 > 0:27:11- ..this eruption could prove fatal.
0:27:25 > 0:27:29- The ash contains toxic chemicals - and shards of volcanic glass.
0:27:33 > 0:27:35- With this much ash on the ground...
0:27:36 > 0:27:40- ..the horses cannot graze - they will have to move or starve.
0:27:45 > 0:27:47- North of the Arctic Circle...
0:27:47 > 0:27:50- ..Greenland's skies... - are filled with little auks.
0:27:59 > 0:28:05- At just 20cm long, they're one of - the smallest seabirds of the North.
0:28:07 > 0:28:11- Each year, the auks - return to the same breeding grounds.
0:28:13 > 0:28:18- As they arrive, couples usually - reoccupy the previous year's nest.
0:28:20 > 0:28:24- Good nesting spots - are fiercely defended.
0:28:44 > 0:28:47- Once their territorial disputes - are settled...
0:28:48 > 0:28:51- ..they can concentrate - on more important matters.
0:29:01 > 0:29:04- The auks have thrived - in this rugged land.
0:29:06 > 0:29:10- More than 30 million of them - come to Greenland to breed.
0:29:11 > 0:29:14- But they will only remain here - for a few months.
0:29:22 > 0:29:27- Greenland, the world's largest - island, is sparsely populated.
0:29:56 > 0:30:00- 80% of the island is blanketed - by a massive layer of ice...
0:30:01 > 0:30:04- ..equivalent to 1.7 - million square kilometres...
0:30:05 > 0:30:07- ..and over a kilometre deep.
0:30:11 > 0:30:14- Under sufficient pressure, - ice flows.
0:30:14 > 0:30:18- And Greenland's rivers of ice, - the glaciers, are accelerating.
0:30:18 > 0:30:21- That may be down to - the temperature rising.
0:30:24 > 0:30:27- Some of them - flow as fast as 20m every day...
0:30:27 > 0:30:30- ..as they move to the coast.
0:30:34 > 0:30:38- Here, the glaciers shatter - and collapse into the sea.
0:30:52 > 0:30:55- Few creatures - survive this harsh landscape.
0:30:56 > 0:30:59- But one has become an expert.
0:31:00 > 0:31:04- The polar bear is the world's - largest land predator...
0:31:04 > 0:31:08- ..but it mainly hunts on the ice...
0:31:08 > 0:31:11- ..using its expertise to hunt seals.
0:31:13 > 0:31:18- It's believed polar bears - have descended from brown bears...
0:31:18 > 0:31:22- ..that became isolated - by glaciers during the Ice Age.
0:31:24 > 0:31:27- They've managed - to adapt and thrive.
0:31:30 > 0:31:35- White fur provides camouflage while - their bulk and a layer of fat...
0:31:35 > 0:31:37- ..stop them from freezing.
0:31:38 > 0:31:42- They can smell prey - up to 40 kilometres away...
0:31:43 > 0:31:46- ..and rip it apart - with their sharp teeth and claws.
0:31:47 > 0:31:51- This powerful hunter - leads a precarious existence.
0:31:51 > 0:31:56- Its survival depends on regular - movements of ice and prey.
0:32:02 > 0:32:05- The sea is full of ice remnants.
0:32:09 > 0:32:13- In recent years, icebergs - are becoming more numerous...
0:32:13 > 0:32:16- ..and some are huge.
0:32:16 > 0:32:21- In 2010, a chunk of ice measuring - over 250 square kilometres...
0:32:22 > 0:32:25- ..sheared off from a glacier - and headed out to sea.
0:32:54 > 0:33:00- These floating icebergs flow with - the current, sometimes for months...
0:33:00 > 0:33:02- ..before slowly melting away.
0:33:08 > 0:33:11- If all Greenland's ice cap - were to thaw...
0:33:11 > 0:33:16- ..it would raise the earth's oceans - by more than six metres.
0:33:19 > 0:33:23- Warmer winters and seas...
0:33:23 > 0:33:28- ..mean that the North's snow and ice - are vanishing at an increasing rate.
0:33:34 > 0:33:37- In some places, - land is being exposed...
0:33:37 > 0:33:40- ..for the first time - in thousands of years.
0:33:46 > 0:33:49- In Iceland, a thaw is also underway.
0:33:50 > 0:33:53- The volcano is still active.
0:33:53 > 0:33:57- The eruptions - may disrupt life for humans...
0:33:57 > 0:34:00- ..but here, - they're part of the natural order.
0:34:00 > 0:34:03- Much of the ash - is dispersed by the wind...
0:34:04 > 0:34:08- ..preventing large areas - from becoming contaminated.
0:34:10 > 0:34:14- In the aftermath of a disaster, - life returns quickly.
0:34:16 > 0:34:19- The first plants to reappear...
0:34:19 > 0:34:24- ..push their roots down through the - toxic ash and into the soil below.
0:34:25 > 0:34:30- In just a few years, this wilderness - will be covered with vegetation.
0:34:40 > 0:34:42- In the north of the island...
0:34:42 > 0:34:46- ..receding ice brings a more - varied menu for the Arctic fox.
0:34:51 > 0:34:55- When food is scarce, - foxes leave their territories...
0:34:55 > 0:34:58- ..to forage further afield.
0:34:59 > 0:35:04- For some, winter coats are already - giving way to shorter, summer fur.
0:35:08 > 0:35:11- He has a better chance of survival - on his own.
0:35:11 > 0:35:13- Although they mate for life...
0:35:13 > 0:35:18- ..pairs may be driven many miles - apart in their search for food.
0:35:22 > 0:35:26- A measly mussel - won't fill an empty stomach.
0:35:35 > 0:35:40- With spring temperatures - reaching 10 degrees Celsius...
0:35:40 > 0:35:45- ..it's time for the male fox - to start breeding again.
0:35:45 > 0:35:49- It's time to rekindle his passion.
0:35:49 > 0:35:51- WAILS
0:36:24 > 0:36:28- This pair has probably - produced cubs in the past.
0:36:40 > 0:36:43- It's a happy reunion - but they're not alone.
0:36:46 > 0:36:48- Another vixen is nearby.
0:36:53 > 0:36:55- Strangers aren't welcome...
0:36:55 > 0:36:58- ..so these foxes - must know one another.
0:37:01 > 0:37:05- She's probably a daughter - from last year's litter.
0:37:05 > 0:37:08- Right now, three's a crowd.
0:37:27 > 0:37:29- If the mating is successful...
0:37:29 > 0:37:32- ..up to 18 cubs - should arrive in a few weeks.
0:37:33 > 0:37:36- They will be brought up - by both parents.
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0:37:54 > 0:37:58- Near the mainland's forests, - temperatures are on the rise.
0:37:58 > 0:38:01- The snow and ice - make way for the tundra.
0:38:02 > 0:38:06- It's time for the black grouse - to find a partner.
0:38:06 > 0:38:08- It's decided by a fight.
0:38:14 > 0:38:16- This is a grouse duel.
0:38:25 > 0:38:27- In an open-air arena.
0:38:29 > 0:38:31- Males battle ferociously...
0:38:31 > 0:38:35- ..sometimes over only - a few square metres of land.
0:38:39 > 0:38:41- But it's more than just a fight.
0:38:41 > 0:38:43- A crowd gathers.
0:38:46 > 0:38:49- Including a number of females.
0:38:51 > 0:38:54- The victor claims its prize.
0:39:07 > 0:39:12- By early June, life in the lowlands - of Finland is in full bloom.
0:39:14 > 0:39:17- Despite - sometimes hunting in packs...
0:39:17 > 0:39:22- ..lemmings usually prefer - a solitary lifestyle.
0:39:22 > 0:39:27- The popular story that lemmings - engage in mass suicide is pure myth.
0:39:31 > 0:39:36- These rodents are on the move, - but they're not looking for cliffs.
0:39:39 > 0:39:41- They're looking for mates.
0:39:50 > 0:39:55- The huge variation in temperature - between winter and summer...
0:39:55 > 0:39:59- ..presents a challenge - to almost all life here.
0:40:08 > 0:40:12- The crane that migrated early - has lost its eggs to the cold.
0:40:15 > 0:40:20- For one late arrival, - the warmer weather provides hope.
0:40:22 > 0:40:26- But life is far from simple - for this jaunty traveller.
0:40:29 > 0:40:32- A red fox - is searching for his next meal.
0:40:39 > 0:40:41- Soaring temperatures...
0:40:41 > 0:40:46- ..make the marshland a perfect - breeding ground for insects.
0:40:50 > 0:40:55- If her chicks are going to hatch, - the crane must stay on the nest.
0:40:56 > 0:40:59- The flies are problematic.
0:41:08 > 0:41:11- Across much of Scandinavia, - heat rather than ice...
0:41:12 > 0:41:14- ..is causing problems.
0:41:16 > 0:41:21- A few months back, Norway's peaks - and valleys were snow covered.
0:41:21 > 0:41:25- Now, temperatures - are reaching 30 degrees Celsius.
0:41:29 > 0:41:31- This country...
0:41:31 > 0:41:35- ..sees some of the greatest - variations in temperature on earth.
0:41:35 > 0:41:38- Bad news for musk oxen.
0:41:39 > 0:41:42- They are still wearing - their winter coats.
0:41:46 > 0:41:50- In these temperatures, - overheating can be fatal.
0:41:51 > 0:41:55- The answer? A dip in a cool lake.
0:42:01 > 0:42:04- It might get rid - of the nasty smell too!
0:42:07 > 0:42:10- Male musk oxen have a pungent smell.
0:42:17 > 0:42:20- The scent - is attractive to a female.
0:42:36 > 0:42:40- In the north of Iceland, - kittiwakes are taking the plunge.
0:42:47 > 0:42:52- With much of their life spent at - sea, a freshwater bath is a treat.
0:43:04 > 0:43:07- But their squawking - has attracted attention.
0:43:17 > 0:43:21- A fox family, including - offspring with rare white coats.
0:43:33 > 0:43:37- Seabirds - are a ready meal for the foxes.
0:43:37 > 0:43:40- But there are guardians nearby.
0:43:47 > 0:43:49- With the nest nearby...
0:43:49 > 0:43:54- ..these swans prevent the fox - from having a clear route.
0:44:15 > 0:44:17- But the fox is determined.
0:44:32 > 0:44:34- In the nearby foothills...
0:44:34 > 0:44:38- ..other creatures - are celebrating their survival.
0:44:39 > 0:44:43- The wild horses have survived - the volcano and found grazing land.
0:44:48 > 0:44:52- A bit of ash isn't going to - deter these resilient animals.
0:44:56 > 0:44:59- They are used to danger.
0:44:59 > 0:45:04- Ice, fast-flowing rivers, - quicksand as well as volcanoes.
0:45:07 > 0:45:10- Only the strongest have survived.
0:45:10 > 0:45:15- These horses are much hardier - than their southern relatives.
0:45:31 > 0:45:35- At last, there may be fresh meat - on the menu for the foxes.
0:45:37 > 0:45:41- They've managed - to surround the kittiwakes.
0:45:50 > 0:45:55- The birds know they're safe if they - stay in the middle of the water.
0:45:56 > 0:45:58- But a sick bird stays on land.
0:46:02 > 0:46:03- The fox seizes its chance.
0:46:29 > 0:46:33- In Finland, perseverance - also produces results.
0:46:37 > 0:46:40- A new generation of cranes - has emerged.
0:46:55 > 0:47:00- In the wild lands of the North, - change is the only constant.
0:47:02 > 0:47:05- The landscape and climate...
0:47:05 > 0:47:07- ..will always pose a challenge.
0:47:12 > 0:47:14- Life adapts and thrives...
0:47:15 > 0:47:18- ..surviving - in the most unlikely places...
0:47:19 > 0:47:22- ..against seemingly impossible odds.
0:47:29 > 0:47:34- In these wild lands - forged by fire and ice...
0:47:34 > 0:47:38- ..the raw power of nature - has never been so vivid.
0:47:56 > 0:47:58- S4C Subtitles by Adnod Cyf.
0:47:58 > 0:47:59- .