0:00:31 > 0:00:37The sun is absent for up to half the year in the polar regions.
0:00:37 > 0:00:40When it returns, at the beginning of spring,
0:00:40 > 0:00:44its warmth will transform this magical ice world.
0:01:04 > 0:01:09The greatest seasonal change on our planet is now underway.
0:01:16 > 0:01:22Antarctica is still locked in ice, and surrounded by a frozen ocean.
0:01:22 > 0:01:25Nonetheless, there are signs of spring.
0:01:32 > 0:01:36Adelie penguins are arriving - just the males.
0:01:36 > 0:01:41They've spent five months at sea, where it's warmer than it is on land
0:01:41 > 0:01:46and now they're in a hurry, for spring will be short.
0:01:52 > 0:01:55They have travelled 6,000 miles across the ocean
0:01:55 > 0:01:58since leaving their colony last year,
0:01:58 > 0:02:01and now they're returning to breed.
0:02:01 > 0:02:04They cannot lay their eggs on ice, for they would freeze,
0:02:04 > 0:02:08so they have to come here, where there is bare rock.
0:02:12 > 0:02:13Over the coming months,
0:02:13 > 0:02:16the few parts of Antarctica that are ice-free
0:02:16 > 0:02:20will be the stage on which five million Adelies
0:02:20 > 0:02:22will build their nests.
0:02:28 > 0:02:32To construct one, they need pebbles, and without a good-looking nest,
0:02:32 > 0:02:36a male will be unable to attract a female,
0:02:36 > 0:02:38when they at last arrive.
0:02:38 > 0:02:42An impressive property demonstrates your worth as a mate.
0:02:46 > 0:02:50It takes stones of all shapes and sizes to build a decent nest,
0:02:50 > 0:02:53and finding ones that are just right is not easy.
0:02:58 > 0:03:01So some penguins turn to a life of crime.
0:03:41 > 0:03:43The one who has been robbed seems unaware
0:03:43 > 0:03:48that the thief is just over his shoulder, and looking for more.
0:03:57 > 0:04:00The thief's nest is coming along nicely,
0:04:00 > 0:04:03probably because he keeps a particularly sharp lookout
0:04:03 > 0:04:06for robbers -
0:04:06 > 0:04:08after all, it takes one to know one.
0:04:18 > 0:04:21It's still cold, but the early season sun
0:04:21 > 0:04:24does lift the temperature by a few degrees.
0:04:24 > 0:04:29That, however, can have unexpected, even dangerous consequences.
0:04:36 > 0:04:38The sea is heating faster than the land,
0:04:38 > 0:04:43pulling cold air from the middle of the continent towards the coast.
0:04:47 > 0:04:52These katabatic winds are stronger than any hurricane.
0:04:52 > 0:04:56They are the coldest and the most ferocious on the planet.
0:05:05 > 0:05:08The storms catch many new arrivals by surprise,
0:05:08 > 0:05:12and are the reason that spring here is, in fact, the deadliest season.
0:05:38 > 0:05:41Here, early birds take a great risk.
0:05:45 > 0:05:48Some years, entire colonies are lost,
0:05:48 > 0:05:50buried beneath the snow.
0:05:50 > 0:05:52The survivors of this storm
0:05:52 > 0:05:55must hope that the females prove to be worth the wait
0:05:55 > 0:05:57when they finally decide to turn up.
0:06:06 > 0:06:08Spring in the north of our planet.
0:06:09 > 0:06:12The sun, after an absence of six months,
0:06:12 > 0:06:16breaks the horizon for the first time.
0:06:24 > 0:06:29A female polar bear emerges from her den beneath the snow.
0:06:29 > 0:06:33The sun must be a welcome relief after so long in the darkness.
0:06:39 > 0:06:42Her den is on a high slope,
0:06:42 > 0:06:46well away from hungry male bears who would kill her cubs,
0:06:46 > 0:06:50but close enough to the sea ice where she can find food
0:06:50 > 0:06:52for her extraordinary new family...
0:06:58 > 0:07:00..three young cubs.
0:07:06 > 0:07:09If she can raise them all to independence,
0:07:09 > 0:07:12it'll be a rare achievement.
0:07:32 > 0:07:35One of the cubs is underweight,
0:07:35 > 0:07:39and will be fortunate to survive these early weeks.
0:07:54 > 0:07:59If the family reaches the sea ice, where the female can catch seals,
0:07:59 > 0:08:01her milk will be enriched,
0:08:01 > 0:08:05and the smaller cub will quickly gain size and strength.
0:08:07 > 0:08:11The sea ice, though, is a dangerous place.
0:08:24 > 0:08:28The male polar bear has been out on the frozen ocean all winter.
0:08:28 > 0:08:30Times have been lean,
0:08:30 > 0:08:33and a bear cub would certainly make a welcome snack.
0:08:33 > 0:08:36However, the mainstay of his diet is seals,
0:08:36 > 0:08:39and now is the time when they have their pups.
0:08:42 > 0:08:46The surface of the frozen sea is marked with pressure ridges
0:08:46 > 0:08:49and cracks created by the fluctuating tides.
0:08:52 > 0:08:54Both are good places to look for seals.
0:09:03 > 0:09:06He has detected a seal den beneath the ice.
0:09:07 > 0:09:12Now he must pin-point it, using only his extraordinary sense of smell.
0:09:17 > 0:09:20By treading lightly, he can avoid scaring his prey.
0:09:25 > 0:09:29He will need to punch through a metre of snow to reach the den,
0:09:29 > 0:09:32and if his aim is not exactly on target,
0:09:32 > 0:09:34the seal will certainly escape.
0:10:10 > 0:10:14In fact, the ringed seal abandoned her den
0:10:14 > 0:10:16just a few hours ago
0:10:16 > 0:10:18and her pup has climbed up on to the surface.
0:10:18 > 0:10:23It's more exposed up here, but it's easier to see an approaching bear.
0:10:37 > 0:10:39The pup is well camouflaged.
0:10:39 > 0:10:43Difficult to see when its mother has left it to go fishing.
0:10:50 > 0:10:52But he can still smell it.
0:11:21 > 0:11:25Nine out of ten polar bear hunts end in failure.
0:11:31 > 0:11:34The sun's warming effect on the Arctic is increasing
0:11:34 > 0:11:38and the sea ice is showing the first signs of weakening.
0:11:42 > 0:11:46Inland, the northern rivers are still locked in ice.
0:11:49 > 0:11:51The frozen waterfalls are like dams
0:11:51 > 0:11:54holding back billions of tonnes of fresh water
0:11:54 > 0:11:57that has not moved for almost six months.
0:12:00 > 0:12:04The vast watershed lies motionless,
0:12:04 > 0:12:08but as spring advances, it beings to stir.
0:12:13 > 0:12:17The frozen waterfalls start to weaken.
0:12:17 > 0:12:20Above them, the pressure is mounting.
0:12:25 > 0:12:29Now, from high above, whole sections can be seen to be on the move.
0:12:38 > 0:12:42The waterfalls are straining to hold back the force
0:12:42 > 0:12:44that is building up above them.
0:12:51 > 0:12:54The dam bursts...
0:12:54 > 0:12:56and the river is unleashed.
0:13:24 > 0:13:28Millions of tonnes of ice grind their way downstream,
0:13:28 > 0:13:32driven by the unstoppable force of the meltwater.
0:13:41 > 0:13:44Boulders and trees are plucked from the bank side.
0:13:47 > 0:13:51Within just a few days, the rivers of the north are all running.
0:13:51 > 0:13:55The Arctic's fresh water is flowing again.
0:14:06 > 0:14:10These vast floods contain 10% of the world's fresh water
0:14:10 > 0:14:15and as they enter the ocean, they accelerate the break-up.
0:14:15 > 0:14:18Soon, an area of sea ice the size of Australia
0:14:18 > 0:14:22will vanish from the Arctic Ocean.
0:14:28 > 0:14:33As the huge ice-sheet breaks up, wildlife returns to the North.
0:14:44 > 0:14:48The polar bear mother has made it to the edge of the sea-ice,
0:14:48 > 0:14:51but the smallest cub is nowhere to be seen.
0:14:54 > 0:14:56It's a sad outcome,
0:14:56 > 0:14:59but the disappearance improves the chances of the remaining two,
0:14:59 > 0:15:03who now have more milk to share.
0:15:06 > 0:15:09Having led her cubs to the edge of the ice,
0:15:09 > 0:15:12the mother's next challenge is to catch a seal.
0:15:17 > 0:15:20Not easy with these two in tow!
0:15:24 > 0:15:26CUB GRUNTS
0:15:35 > 0:15:39Her prey beneath the ice can detect the slightest vibration,
0:15:39 > 0:15:41especially from bears.
0:15:41 > 0:15:45And this is not the stealthiest of hunting parties.
0:15:45 > 0:15:47BEAR GROWLS
0:15:52 > 0:15:56Leaving her cubs behind, however, is not an option -
0:15:56 > 0:15:59a male bear would eat one in a moment.
0:16:06 > 0:16:09This is not going to be easy.
0:16:19 > 0:16:26It seems that the cubs already see themselves as fearsome hunters,
0:16:26 > 0:16:31but they're still young enough to accept their mother's discipline.
0:16:31 > 0:16:33It's the naughty corner for you!
0:16:54 > 0:16:57This is not going to be their lucky morning.
0:16:57 > 0:17:01They saw no sign of a seal and the cubs are hungry again.
0:17:01 > 0:17:06The mother has been nursing for four months without once eating herself,
0:17:06 > 0:17:08and now her milk is drying up.
0:17:10 > 0:17:14She must catch a seal soon, or the whole family will starve.
0:17:18 > 0:17:22The challenge of finding food is getting harder.
0:17:22 > 0:17:25She needs the sea-ice as a platform from which to hunt
0:17:25 > 0:17:28and it's breaking up faster with each passing day.
0:17:32 > 0:17:35Even the ice around the coast is starting to break.
0:17:37 > 0:17:41The first cracks here are eagerly awaited by some...
0:17:52 > 0:17:54..narwhals.
0:17:58 > 0:18:01The unicorns of the North are on a mission -
0:18:01 > 0:18:02to reach the new fishing grounds
0:18:02 > 0:18:07in the bays that have been frozen up all winter, but are now opening up.
0:18:16 > 0:18:19To get to them, the narwhals must travel down leads -
0:18:19 > 0:18:22temporary cracks in the ice.
0:18:22 > 0:18:26But these new roads could close at any time,
0:18:26 > 0:18:29cutting off the air that they need to breathe.
0:18:32 > 0:18:37The road narrows until there's barely room for one-way traffic.
0:18:37 > 0:18:40Then, a surprise...
0:18:40 > 0:18:43narwhals coming from the other direction.
0:18:47 > 0:18:50It's a stand-off.
0:18:50 > 0:18:53Each team faces an armoury of sharp tusks.
0:19:11 > 0:19:14Finally, one side concedes
0:19:14 > 0:19:18and everyone continues in the same direction.
0:19:25 > 0:19:30Within a week, the remaining bays break wide open,
0:19:30 > 0:19:34and the narwhals turn their attention to social matters.
0:19:42 > 0:19:46No-one knows exactly what the narwhal's tusk is for.
0:19:46 > 0:19:48Some say it's used for fencing,
0:19:48 > 0:19:52yet these exchanges are too gentle to be real fights.
0:20:07 > 0:20:09Perhaps these encounters
0:20:09 > 0:20:14are to remind each animal of where it stands in narwhal society.
0:20:16 > 0:20:17We may never know.
0:20:33 > 0:20:36Bizarre creatures appear as if from nowhere.
0:20:38 > 0:20:42The tiny plankton they eat have been fuelled by the increasing warmth
0:20:42 > 0:20:46of the sun and fertilised by the nutrients
0:20:46 > 0:20:50brought down by the great rivers and released from the melting sea-ice.
0:20:52 > 0:20:55Sea gooseberries strain the water with their stinging filaments,
0:20:55 > 0:20:59their beating cilia scatter the sun's rays
0:20:59 > 0:21:01into dazzling bursts of colour.
0:21:08 > 0:21:12Beneath the breaking sea ice, a predatory sea slug
0:21:12 > 0:21:16flies through the water on translucent wings.
0:21:16 > 0:21:19It's on the trail of a peculiar swimming snail.
0:21:32 > 0:21:35And now the most voracious of the plankton-eaters
0:21:35 > 0:21:37swim up from the depths...
0:21:37 > 0:21:40Arctic cod.
0:21:43 > 0:21:46SEAGULLS CRY
0:21:46 > 0:21:51The shoals can be enormous, some containing 500 million fish
0:21:51 > 0:21:56and predators travel hundreds of miles to feast on them.
0:21:58 > 0:22:01The cod harvest is THE annual event
0:22:01 > 0:22:04for the birds and seals of the far North.
0:22:08 > 0:22:10For just a short period,
0:22:10 > 0:22:14the combination of the strengthening sun, the newly-flowing rivers
0:22:14 > 0:22:20and the breaking sea ice make the Arctic Ocean teem with life.
0:22:27 > 0:22:30The land is also transformed by the sun's heat.
0:22:33 > 0:22:37The small patches of bare ground that appear are darker than the snow
0:22:37 > 0:22:40so they absorb more of the sun's energy.
0:22:42 > 0:22:44This accelerates the melt.
0:22:52 > 0:22:55The Arctic tundra is unveiled.
0:23:03 > 0:23:08By tracking the sun, Arctic poppies catch its rays around the clock,
0:23:08 > 0:23:12so their flowers are always warmer than their surroundings.
0:23:17 > 0:23:23For early season insects, this warmth is even more valuable
0:23:23 > 0:23:26than nectar if they're to stay active in the cold.
0:23:36 > 0:23:39The woolly bear caterpillar does not need the warmth from flowers
0:23:39 > 0:23:41to kick-start its spring.
0:23:41 > 0:23:45It's always the first insect to appear after the snow retreats
0:23:45 > 0:23:49and the story of how it does so is truly astonishing.
0:23:53 > 0:23:57At the start of spring, the caterpillar eats as fast as it can,
0:23:57 > 0:24:02as indeed it must, for this far north, the season will be brief.
0:24:04 > 0:24:07The days shorten only too soon, but the caterpillar has not yet
0:24:07 > 0:24:12got enough reserves to transform itself into a moth.
0:24:12 > 0:24:15It can't leave the Arctic, for it can't fly,
0:24:15 > 0:24:18so it settles down beneath a rock.
0:24:20 > 0:24:22The sun's warmth rapidly dwindles.
0:24:29 > 0:24:32Beneath the rock, the caterpillar is out of the wind,
0:24:32 > 0:24:35but the cold penetrates deep into the ground.
0:24:36 > 0:24:39Soon, its heart stops beating.
0:24:39 > 0:24:44It ceases to breathe, and its body starts to freeze -
0:24:44 > 0:24:47first its gut, then its blood.
0:25:10 > 0:25:13Spring.
0:25:13 > 0:25:19After four months of darkness, the Arctic begins to thaw.
0:25:21 > 0:25:25And the caterpillar rises from the dead.
0:25:34 > 0:25:37By the time the first shoots of willow appear
0:25:37 > 0:25:39in the early spring, the woolly bear is already eating.
0:25:42 > 0:25:46But no matter how fast the woolly bear eats, it will not have time
0:25:46 > 0:25:48to gather enough food this year, either,
0:25:48 > 0:25:52and the cold closes in once again.
0:26:14 > 0:26:17Year after year, the caterpillar slows down in the autumn
0:26:17 > 0:26:20and then freezes solid.
0:26:28 > 0:26:32But eventually, a very special spring arrives.
0:26:35 > 0:26:38This one will be its last.
0:26:44 > 0:26:49It's now 14 years old - the world's oldest caterpillar.
0:26:49 > 0:26:52Its remaining days now become frantic.
0:26:52 > 0:26:55It starts to weave a silk cocoon.
0:26:57 > 0:27:03Inside, its body is changing into one that can fly and search,
0:27:03 > 0:27:07abilities that will be crucial in the days ahead.
0:27:10 > 0:27:14It's waited over a decade for this spring and now, its time is near.
0:27:19 > 0:27:23All across the Arctic, moths are emerging.
0:27:23 > 0:27:26After completing their 14-year preparation,
0:27:26 > 0:27:30they now have just a few days to find a partner and mate.
0:27:36 > 0:27:41No life illustrates more vividly the shortness of the Arctic spring
0:27:41 > 0:27:46or the struggle to survive in this most seasonal of places.
0:27:54 > 0:27:56As spring advances,
0:27:56 > 0:27:59the transformation of the tundra continues.
0:28:29 > 0:28:31THEY SQUEAK
0:28:44 > 0:28:47CHEEPING
0:28:50 > 0:28:52Migrants begin arriving from the south
0:28:52 > 0:28:58and suddenly the tundra is alive with birds and chicks.
0:29:12 > 0:29:16The Arctic's transformation is complete.
0:29:22 > 0:29:28This influx of life is good news for some permanent residents.
0:29:34 > 0:29:37Food is rarely plentiful out on the tundra.
0:29:37 > 0:29:42The Arctic wolves must make the most of this boom while it lasts.
0:30:07 > 0:30:09HONKING
0:30:38 > 0:30:42The wolves must gather as much food as they can.
0:30:42 > 0:30:46Many miles from here, other members of the pack are relying on them.
0:30:46 > 0:30:49HOWLING
0:31:00 > 0:31:03This barren landscape is a hard place to make a living,
0:31:03 > 0:31:07forcing wolf packs to be smaller here than further south.
0:31:14 > 0:31:17Six hungry mouths to feed.
0:31:17 > 0:31:20The cubs are just over a month old.
0:31:20 > 0:31:22BARKING AND YELPING
0:31:31 > 0:31:35The ducks are devoured instantly, but on the long journey home,
0:31:35 > 0:31:39they also caught an Arctic hare, a mainstay of the tundra diet,
0:31:39 > 0:31:43and one the cubs seem to be particularly keen on.
0:31:52 > 0:31:55Uneaten food is usually hidden for leaner times,
0:31:55 > 0:31:59but there will be no leftovers today.
0:31:59 > 0:32:02The cubs are growing fast and are always hungry.
0:32:10 > 0:32:12GROWLING
0:32:18 > 0:32:23The good times are certainly back, but these white wolves remind us
0:32:23 > 0:32:25of the Arctic's less welcoming side.
0:32:27 > 0:32:31Their coats are pale to conceal them during the long, snowy winter.
0:32:34 > 0:32:37It's easy to forget that one month ago,
0:32:37 > 0:32:40this land was a barren, white desert.
0:32:48 > 0:32:51At the southern end of our planet,
0:32:51 > 0:32:55the Antarctic sea ice is still at its greatest extent.
0:32:57 > 0:33:00But there are a few islands on its outer edge
0:33:00 > 0:33:03that the sea ice never quite reaches.
0:33:07 > 0:33:11South Georgia is washed by the rich waters of the Southern Atlantic
0:33:11 > 0:33:14and the comparative warmth of the sea
0:33:14 > 0:33:16takes the edge off the vicious southern winter.
0:33:24 > 0:33:28It's even possible for a few hardy animals,
0:33:28 > 0:33:33like the wandering albatross, to live here throughout the whole year.
0:33:42 > 0:33:47The enormous albatross chicks take 13 months to fledge,
0:33:47 > 0:33:51so they have no choice but to sit here throughout the winter.
0:33:51 > 0:33:54It can't be easy, but the thick layer of fluffy down
0:33:54 > 0:33:56keeps out the worst of the cold.
0:33:57 > 0:34:01Their parents travel thousands of miles to collect the fish
0:34:01 > 0:34:04and squid they need to stay warm and to grow.
0:34:13 > 0:34:19The season is turning and storms blow in with little warning.
0:34:27 > 0:34:31King penguins have also been here all winter.
0:34:35 > 0:34:39Their chicks survive by huddling in creches to conserve their heat.
0:34:39 > 0:34:45A solitary bird here standing alone would quickly die of exposure.
0:34:45 > 0:34:50It seems for a hardy few, violent storms are a price worth paying
0:34:50 > 0:34:55for year-round fishing in the rich waters of the southern ocean.
0:35:01 > 0:35:05The penguins have had the beach to themselves all winter,
0:35:05 > 0:35:09but that is a luxury that will not last.
0:35:15 > 0:35:20As the winter storms subside, life begins to return.
0:35:31 > 0:35:35For half of the year, South Georgia has the greatest concentration
0:35:35 > 0:35:37of sea birds in the world
0:35:37 > 0:35:40and most of them arrive in the early spring.
0:35:48 > 0:35:51Macaroni penguins make the most impressive entrance -
0:35:51 > 0:35:54over five million pairs of them.
0:35:54 > 0:35:56They are the world's most numerous penguin
0:35:56 > 0:35:59and half of them are now here.
0:36:00 > 0:36:02The arrival is complete.
0:36:07 > 0:36:11Courtship is next on South Georgia's busy spring schedule.
0:36:17 > 0:36:21The wandering albatross has the most elaborate display.
0:36:21 > 0:36:23MIXED-PITCH "POPPING"
0:36:27 > 0:36:31These two are renewing their bonds after being months apart.
0:36:37 > 0:36:39Wanderers pair up in their teens
0:36:39 > 0:36:42and can spend a further 50 years together -
0:36:42 > 0:36:45one of the longest partnerships in the animal world.
0:37:10 > 0:37:13By the middle of spring, the snows have cleared
0:37:13 > 0:37:16from the coves and the low ground.
0:37:16 > 0:37:19The beaches are almost free of ice too,
0:37:19 > 0:37:23but that isn't the biggest change facing the king penguins.
0:37:23 > 0:37:30Their peaceful waterfront has turned into an obstacle course of blubber.
0:37:33 > 0:37:35The elephant seals have arrived.
0:37:38 > 0:37:41This beach now contains a greater mass of animals
0:37:41 > 0:37:43than any other in the world.
0:37:54 > 0:37:57The young seals were conceived here a year ago,
0:37:57 > 0:38:00and now that they've been born,
0:38:00 > 0:38:02their mothers are ready to mate again.
0:38:04 > 0:38:09The mating rights on this patch of the beach belong to a beach master.
0:38:09 > 0:38:13His harem contains 50 females -
0:38:13 > 0:38:15females that are coveted by others.
0:38:18 > 0:38:21His authority is being challenged.
0:38:26 > 0:38:29This rival means business.
0:38:41 > 0:38:44This could be the beach master's first serious test
0:38:44 > 0:38:46of his spring campaign.
0:38:54 > 0:38:59The beach master himself weighs four tonnes,
0:38:59 > 0:39:01but this rival is his equal.
0:39:16 > 0:39:20When these titans clash,
0:39:20 > 0:39:22bones crunch.
0:40:04 > 0:40:06He has won the first battle,
0:40:06 > 0:40:10but he may have to defend his harem every hour for the next month.
0:40:12 > 0:40:16If he can stay master of his beach for this period,
0:40:16 > 0:40:19many of the young born here next year will be his.
0:40:24 > 0:40:27It's the end of spring on the wandering albatross's cliffs,
0:40:27 > 0:40:30their season for fledging.
0:40:30 > 0:40:33Last year's chicks have lost their fluffy down
0:40:33 > 0:40:37and step up to the challenge of getting into the air.
0:40:40 > 0:40:43SQUAWKING
0:40:49 > 0:40:54An albatross is not very competent on the ground,
0:40:54 > 0:40:58so until it can fly, it isn't good for much
0:40:58 > 0:40:59and this makes the maiden flight
0:40:59 > 0:41:02THE crucial event in an albatross's life.
0:41:08 > 0:41:11Managing the largest wing span in the world takes practice...
0:41:14 > 0:41:16..lots of it.
0:41:33 > 0:41:35Weeks can go by like this.
0:41:35 > 0:41:39Certainly the winds must be right, but it does appear that for some,
0:41:39 > 0:41:43the problem is something of a mental one.
0:41:57 > 0:41:58At last.
0:42:06 > 0:42:08The Southern Ocean beckons.
0:42:08 > 0:42:13This bird's feet will not touch land again for five years.
0:42:18 > 0:42:201,000 miles further south,
0:42:20 > 0:42:23on the edge of the Antarctic continent,
0:42:23 > 0:42:26the sea ice is only just starting to break.
0:42:26 > 0:42:32But the Adelie penguins' activities are certainly warming up.
0:42:32 > 0:42:36The males have now finished their nests by fair means or foul
0:42:36 > 0:42:40and the females are finally returning,
0:42:40 > 0:42:43just as the weather is improving.
0:42:43 > 0:42:45Now their courtship can begin.
0:42:45 > 0:42:48RHYTHMIC CAWING
0:43:43 > 0:43:47The eggs are laid and the females leave the job of incubating them
0:43:47 > 0:43:51to the males, while they go fishing out on the fragmenting sea ice.
0:44:02 > 0:44:04Killer whales.
0:44:12 > 0:44:15It's teamwork that makes killer whales so dangerous.
0:44:17 > 0:44:19And THIS is a big team.
0:46:14 > 0:46:18There is no real need for the penguins to be alarmed.
0:46:19 > 0:46:22These killer whales are a kind that only eats fish.
0:46:28 > 0:46:31Rising out is simply the best way for the whales to work out
0:46:31 > 0:46:35which cracks lead towards the coast and better fishing.
0:46:48 > 0:46:51A new generation of Adelies steps forth
0:46:51 > 0:46:54into the short Antarctic spring
0:46:54 > 0:46:57to be nurtured by industrious parents who've taken great risks
0:46:57 > 0:47:00to give their young a head start.
0:47:04 > 0:47:08They will need to grow fast if they are to fledge
0:47:08 > 0:47:10and leave before the freeze sets in again.
0:47:12 > 0:47:17It's a battle they will win or lose over the approaching summer.
0:47:41 > 0:47:44To film the entire breeding cycle of the Adelie penguin,
0:47:44 > 0:47:48Frozen Planet sent a team to one of the world's largest colonies,
0:47:48 > 0:47:50at Cape Crozier, Antarctica.
0:47:50 > 0:47:53I've heard so much about it and read so much about it.
0:47:53 > 0:47:56Finally we're going to get there. It's good.
0:47:56 > 0:47:59Cameraman Mark Smith and director Jeff Wilson
0:47:59 > 0:48:02plan to spend the next four months living amongst the penguins
0:48:02 > 0:48:06in a location first visited by the early explorers a century ago.
0:48:08 > 0:48:11So arduous was Scott's winter expedition to Cape Crozier
0:48:11 > 0:48:15that it became known as "the worst journey in the world".
0:48:15 > 0:48:19Wow, it's fantastic!
0:48:21 > 0:48:24Modern means make Mark and Jeff's journey a more comfortable affair,
0:48:24 > 0:48:26but once there, they will be tested
0:48:26 > 0:48:29to the very limits of their endurance.
0:48:34 > 0:48:36The pair arrive in early spring
0:48:36 > 0:48:42with enough supplies to survive the next four months working alone in the Antarctic wilderness.
0:48:42 > 0:48:44We're here!
0:48:45 > 0:48:49Scott's legend of Cape Crozier tells of some extreme weather,
0:48:49 > 0:48:52to say the least,
0:48:52 > 0:48:55so Mark and Jeff take advantage of the clear conditions,
0:48:55 > 0:48:58in the knowledge that the Adelies' arrival is imminent.
0:49:01 > 0:49:04But the next morning, things take a turn for the worse.
0:49:04 > 0:49:06We've just come up to this ridge
0:49:06 > 0:49:09to go and check what it looks like down in the colony.
0:49:09 > 0:49:12ROARING
0:49:12 > 0:49:14But even here you can hear...
0:49:14 > 0:49:18a huge kind of roaring noise
0:49:18 > 0:49:22up on the hill. Never really heard anything like that before.
0:49:27 > 0:49:30Up there, it must be blowing the most almighty gale,
0:49:30 > 0:49:33and that is, pff, you know, just a mile away or something.
0:49:33 > 0:49:36So that means that that could get here very, very quickly.
0:49:36 > 0:49:41So yeah, it makes you slightly scared. It's weird, isn't it?
0:49:41 > 0:49:44The winds here are famously ferocious,
0:49:44 > 0:49:47and with so little experience of this location,
0:49:47 > 0:49:52Mark and Jeff retreat to the relative shelter of their hut.
0:49:52 > 0:49:55I was just stood here thinking, "Well, it can't be too bad,
0:49:55 > 0:49:58"because we haven't seen rocks starting to blow around yet,"
0:49:58 > 0:50:03and just at that moment a rock took off and rolled down there.
0:50:06 > 0:50:10Oh, dear, it's getting stronger.
0:50:11 > 0:50:15By the second day of the storm, the winds reach 80 miles an hour,
0:50:15 > 0:50:18and it's apparent that even getting lunch from the outside larder
0:50:18 > 0:50:20is too risky.
0:50:30 > 0:50:34To their increasing alarm, the storm continues to build.
0:50:36 > 0:50:42All afternoon, it's been blowing about...must have been 100 miles an hour,
0:50:42 > 0:50:45and in the last half-hour it's just got a lot stronger.
0:50:45 > 0:50:47Aside from being utterly terrified,
0:50:47 > 0:50:50there's the added worry that our gear is stashed outside somewhere.
0:50:50 > 0:50:53We didn't have room for it in the hut,
0:50:53 > 0:50:56and we don't know whether it's going to be there in the morning,
0:50:56 > 0:50:59which could spell the end of our trip.
0:50:59 > 0:51:04On the third day of the storm, the winds hit 130 miles an hour.
0:51:04 > 0:51:07The hut starts to shake from its very foundations,
0:51:07 > 0:51:11and Mark and Jeff's situation becomes critical.
0:51:11 > 0:51:12The wind's so strong,
0:51:12 > 0:51:16it's constantly blowing the pilot light out on the paraffin stove,
0:51:16 > 0:51:18so the temperature's dropping.
0:51:18 > 0:51:23The wind's rising. Sounds like the bloody roof's coming off.
0:51:26 > 0:51:30The really scary thing is that had we gone out down to the colony
0:51:30 > 0:51:32and tried to film today,
0:51:32 > 0:51:35there's a very high likelihood that we'd be dead by now.
0:51:35 > 0:51:38And I don't say that lightly.
0:51:38 > 0:51:41There's no way we would have seen this through down there.
0:51:41 > 0:51:44And that is quite sobering.
0:51:52 > 0:51:55After four terrifying days inside the hut,
0:51:55 > 0:51:58the winds finally drop, and Mark and Jeff are keen to see
0:51:58 > 0:52:01what, if any, equipment has survived.
0:52:01 > 0:52:06All the real important stuff, the camera stuff, is all still here,
0:52:06 > 0:52:09and it's still strapped to this rock.
0:52:09 > 0:52:13You have no idea how much joy that gives us.
0:52:13 > 0:52:15We can get on with our jobs now!
0:52:20 > 0:52:23The first things to welcome us to the colony are these skuas,
0:52:23 > 0:52:28which come in and batter us from above.
0:52:35 > 0:52:40At its height, the colony will swell to over half a million penguins,
0:52:40 > 0:52:43and in the 24-hour daylight of the Antarctic summer,
0:52:43 > 0:52:48Mark and Jeff spend all of their waking hours filming.
0:52:48 > 0:52:51Unpredictable weather continues to force the team
0:52:51 > 0:52:56to climb the two miles back to the relative shelter of their hut,
0:52:56 > 0:52:59and Mark devises a novel way of testing the wind speed.
0:53:01 > 0:53:03Stop!
0:53:08 > 0:53:10After six weeks, the first sign that the pair
0:53:10 > 0:53:14might be tiring of their penguin neighbours.
0:53:14 > 0:53:16Over there's a leopard seal.
0:53:16 > 0:53:20It's the first non-penguin-looking animal in two months!
0:53:20 > 0:53:22Will you look at that? It's a leopard seal!
0:53:24 > 0:53:26I was down here filming the penguins coming in,
0:53:26 > 0:53:29followed this penguin that came out of the waves up the beach,
0:53:29 > 0:53:32very nice shot, stopped the shot
0:53:32 > 0:53:36and there in the middle of the frame was this completely white penguin...
0:53:36 > 0:53:39trying to get into the shot.
0:53:39 > 0:53:42We suspect that he might be following us around now.
0:53:45 > 0:53:48Working around the clock for this length of time
0:53:48 > 0:53:51in the presence of half a million screaming penguins
0:53:51 > 0:53:54would test anyone's resolve.
0:53:56 > 0:54:00I hate carrying gear. Hear that? I hate carrying gear. I don't want to do it any more.
0:54:03 > 0:54:07Midway through their trip, after more than 1,000 hours amongst the penguins,
0:54:07 > 0:54:10their grip on reality is beginning to loosen.
0:54:11 > 0:54:14Here we are on the penguin superhighway,
0:54:14 > 0:54:17where the penguins go down to the sea.
0:54:18 > 0:54:23It seems that they follow the American system...
0:54:23 > 0:54:28driving on the right, going down to the sea on the right,
0:54:28 > 0:54:32coming back from the sea on the left as you're facing the sea.
0:54:33 > 0:54:37I'm fairly sure that yesterday they were doing the British system.
0:54:41 > 0:54:46The legendary Cape Crozier weather soon snaps them back into reality.
0:54:46 > 0:54:48I'm just filming the penguins
0:54:48 > 0:54:52with this huge kind of wind storm
0:54:52 > 0:54:54coming over the ice cap,
0:54:54 > 0:54:57the kind of thing we were warned about by the guy who was here before,
0:54:57 > 0:55:01who has been here several years, saying "With skies like this, you should run for home".
0:55:01 > 0:55:04But we're just going to stay and film it.
0:55:04 > 0:55:06Because we're the BBC!
0:55:06 > 0:55:08But in this part of the world,
0:55:08 > 0:55:11working for the BBC doesn't count for much.
0:55:11 > 0:55:14Within minutes, the winds reach hurricane strength,
0:55:14 > 0:55:17and the crew are in serious trouble.
0:55:17 > 0:55:20So, we've got to now venture out and go about a mile up this valley,
0:55:20 > 0:55:25which looks like it's got about 80mph winds blowing down it.
0:55:25 > 0:55:27So it's going to be quite an adventure.
0:55:27 > 0:55:30Bit frightening, though, really.
0:55:30 > 0:55:34After three months, the pair are now fully aware
0:55:34 > 0:55:37- of the strength the winds can reach. - Getting a little stronger now!
0:55:37 > 0:55:39There is a very real danger
0:55:39 > 0:55:43that they could be separated and lost in these white-out conditions.
0:56:06 > 0:56:08- We're going to go- BLEEP.
0:56:11 > 0:56:14Two terrifying hours later, and their relief
0:56:14 > 0:56:17at finally reaching the hut is tangible.
0:56:17 > 0:56:19THEY LAUGH
0:56:21 > 0:56:24With a month still to go at Cape Crozier,
0:56:24 > 0:56:28Mark, Jeff and the penguins will face many more storms like this.
0:56:28 > 0:56:30But it seems their greatest challenge
0:56:30 > 0:56:34will be to maintain their sanity.
0:56:34 > 0:56:37Here we are, travelling through the Antarctic by sled.
0:56:37 > 0:56:40We're being pulled by a herd of huskies. Oh!
0:56:43 > 0:56:4812 of them panting out front, breath steaming from their mouths.
0:56:48 > 0:56:50And as we go along,
0:56:50 > 0:56:52we see the happy people waving at us.
0:57:24 > 0:57:27Subtitles by Red Bee Media Ltd
0:57:27 > 0:57:30E-mail subtitling@bbc.co.uk