0:00:08 > 0:00:12In the winter of 1807,
0:00:12 > 0:00:15a lone fur trapper journeyed deep
0:00:15 > 0:00:17into the heart of the Rocky Mountains.
0:00:21 > 0:00:22Somewhere near the headwaters
0:00:22 > 0:00:27of the Yellowstone river he found a lost world.
0:00:36 > 0:00:37A wonderland.
0:00:39 > 0:00:44Ruled by ice, fire and brimstone.
0:00:51 > 0:00:57A world of extremes that challenges all that strive to live here.
0:01:37 > 0:01:42A place that has become perhaps the most treasured wilderness on Earth.
0:02:15 > 0:02:17Winter in Yellowstone.
0:02:17 > 0:02:18GRUNTS
0:02:20 > 0:02:22-40 degrees.
0:02:24 > 0:02:27Fahrenheit or centigrade,
0:02:27 > 0:02:34it doesn't really matter, at -40 the two scales read the same.
0:02:36 > 0:02:40For half the year Yellowstone is frozen solid.
0:02:44 > 0:02:47Yet in the middle of this ice world
0:02:47 > 0:02:49there is scalding heat.
0:02:54 > 0:02:59This is no ordinary place and this is no ordinary winter.
0:03:08 > 0:03:12The fate of everything here lies in the hands of forces
0:03:12 > 0:03:14of almost unimaginable power.
0:03:23 > 0:03:25Yellowstone is deep in the heart
0:03:25 > 0:03:29of the Rocky Mountains of North America,
0:03:29 > 0:03:33an isolated high plateau defended by rugged peaks.
0:03:40 > 0:03:44And its location is what makes it so different.
0:03:47 > 0:03:49Right beneath Yellowstone
0:03:49 > 0:03:55a unique quirk of geology means that molten rock from deep in the earth
0:03:55 > 0:03:58comes unusually close to the frozen surface.
0:04:03 > 0:04:05No-one knows why it happens right here,
0:04:05 > 0:04:11but its impact is what has made Yellowstone world famous.
0:04:31 > 0:04:36Yellowstone is the most extensive geothermal area on Earth.
0:04:41 > 0:04:43It has over 10,000 thermal wonders
0:04:43 > 0:04:47and more geysers than the rest of the world put together.
0:04:59 > 0:05:04Old Faithful is Yellowstone's most well known geyser.
0:05:04 > 0:05:08It shoots 5,000 gallons of water 150 feet
0:05:08 > 0:05:10into the air almost every hour.
0:05:21 > 0:05:25But the forces that fuel this spectacular display
0:05:25 > 0:05:28have an influence far greater than we can see on the surface.
0:05:31 > 0:05:35Paradoxically it's all this underground heat that helps make
0:05:35 > 0:05:41the Yellowstone winter one of the coldest and toughest in America.
0:05:48 > 0:05:53It's November and winter is beginning to take hold.
0:05:53 > 0:05:55EAGLE CALLS
0:06:01 > 0:06:04WOLF HOWLS
0:06:18 > 0:06:24As it gets colder, one animal here gets stronger -
0:06:24 > 0:06:25wolves.
0:06:25 > 0:06:28The winter is their time.
0:06:29 > 0:06:33Gradually, it weakens their prey.
0:06:33 > 0:06:35WOLVES HOWL
0:06:54 > 0:06:58This is the Druid wolf pack, one of the largest and most
0:06:58 > 0:06:59powerful in Yellowstone.
0:07:29 > 0:07:33The pack have this bull elk surrounded.
0:07:35 > 0:07:37But there's a problem.
0:07:39 > 0:07:41The pack won't follow the bull into the river.
0:07:41 > 0:07:45They won't risk freezing to death in the ice cold water.
0:07:54 > 0:07:57What's more, now the elk's antlers are at just the right height
0:07:57 > 0:07:59to keep the wolves at bay.
0:08:12 > 0:08:14It's stalemate.
0:08:17 > 0:08:21But it's now the elk that has a problem of his own.
0:08:23 > 0:08:25Although it's only knee deep,
0:08:25 > 0:08:29he can't stay in this freezing water forever.
0:08:37 > 0:08:42A young female is not prepared to let him go.
0:08:47 > 0:08:50But the elk is strong.
0:08:50 > 0:08:54One on one, he has the advantage.
0:09:05 > 0:09:07Her only support is another youngster.
0:09:10 > 0:09:13They are neither strong
0:09:13 > 0:09:16nor experienced enough to bring this elk down.
0:09:16 > 0:09:18But it's enough to make him turn
0:09:18 > 0:09:20and run.
0:09:23 > 0:09:27Back to the river where he knows they won't follow.
0:09:36 > 0:09:39But the longer he stays in the freezing water,
0:09:39 > 0:09:41the weaker he will get.
0:09:45 > 0:09:50Others before him have waited here too long
0:09:50 > 0:09:53and wolves are patient.
0:09:57 > 0:10:01Right now his strength is his only advantage.
0:10:01 > 0:10:03He has to try again.
0:10:10 > 0:10:13This time even the young wolves stay put.
0:10:15 > 0:10:20Without the support of the pack they never really stood a chance,
0:10:20 > 0:10:24and the pack have already decided that this early in the winter
0:10:24 > 0:10:28a bull elk in his prime is just too strong.
0:10:31 > 0:10:35But as the winter gets colder and the snow gets deeper,
0:10:35 > 0:10:37the tables will turn.
0:10:48 > 0:10:50By the end of November,
0:10:50 > 0:10:54the arc of the sun barely breaks above the trees.
0:10:56 > 0:10:59As its angle decreases,
0:10:59 > 0:11:01so does its power.
0:11:13 > 0:11:17And as the sun loses its hold over the land,
0:11:17 > 0:11:20other forces begin to take over.
0:11:24 > 0:11:27Yellowstone has a dark secret
0:11:27 > 0:11:30that affects everything that lives here,
0:11:30 > 0:11:32especially in the winter.
0:11:44 > 0:11:48It's only from high above ground that we start to get a glimpse
0:11:48 > 0:11:50of the true nature of this place.
0:11:55 > 0:11:57Yellowstone is a giant bowl,
0:11:57 > 0:12:0250 miles wide, right in the middle of the Rocky Mountains.
0:12:05 > 0:12:07There's nowhere else like it.
0:12:09 > 0:12:12And there's only one thing that could have created it.
0:12:19 > 0:12:23Three miles beneath this frozen surface is a colossal chamber
0:12:23 > 0:12:26of molten rock.
0:12:26 > 0:12:30Today it powers Yellowstone's geysers,
0:12:30 > 0:12:35but every million years or so the pressure in this magma gets critical
0:12:35 > 0:12:38and the chamber explodes.
0:12:40 > 0:12:45The last eruption, 640,000 years ago,
0:12:45 > 0:12:49was more than a thousand times larger than Mount St Helens.
0:12:52 > 0:12:56It blasted away mountains and ejected hundreds of cubic miles
0:12:56 > 0:13:01of debris into the atmosphere, burying half the USA with ash.
0:13:06 > 0:13:11The heart of Yellowstone is one of the world's biggest volcanoes.
0:13:14 > 0:13:18One day, it will erupt again.
0:13:18 > 0:13:21It could be today
0:13:21 > 0:13:23or in another million years.
0:13:25 > 0:13:29But even as the volcano is sleeping,
0:13:29 > 0:13:32breathing quietly through its geysers,
0:13:32 > 0:13:36it has a profound effect on Yellowstone's winter.
0:13:40 > 0:13:46The volcano made Yellowstone's giant bowl, but it didn't stop there.
0:13:48 > 0:13:50Ever since, the huge pressure
0:13:50 > 0:13:55below the surface has been pushing it higher into the air
0:13:55 > 0:13:58and as it gets higher it gets colder.
0:14:00 > 0:14:05And now at its present altitude of 8,000 feet this giant bowl
0:14:05 > 0:14:09simply accumulates freezing air from the surrounding mountains.
0:14:11 > 0:14:16In the winter, the sleeping volcano becomes a giant deep freeze.
0:14:28 > 0:14:32On the open plateau, right in the middle of this frozen volcano,
0:14:32 > 0:14:36is an animal that has lived here since the last ice age.
0:14:39 > 0:14:44Bison are exposed to the worst of the Yellowstone winter,
0:14:44 > 0:14:46but they are built for it.
0:14:49 > 0:14:53Their thick coat is such good insulation that they only need
0:14:53 > 0:14:55a tiny amount of energy to keep warm,
0:14:55 > 0:15:00so they slow their metabolism right down and concentrate on feeding.
0:15:08 > 0:15:12With massive neck muscles they sweep their heads down through the snow
0:15:12 > 0:15:14to get to the grass beneath.
0:15:17 > 0:15:22But the grass has long ago put its summer goodness down into its roots
0:15:22 > 0:15:26and now has about the same nutritional value as cardboard.
0:15:31 > 0:15:35They will need to do all they can to save energy if they are to ward off
0:15:35 > 0:15:38starvation until spring returns.
0:15:47 > 0:15:51As the winter strengthens its grip, elk move into more sheltered valleys
0:15:51 > 0:15:53at the edge of Yellowstone.
0:15:55 > 0:15:58They don't have the bison's ability to move deep snow.
0:16:02 > 0:16:08But this brings them into the territory of the Druid pack.
0:16:22 > 0:16:25As the grazers are beginning to weaken,
0:16:25 > 0:16:28life for the wolves is getting easier.
0:16:34 > 0:16:38They are now successfully hunting about twice a week.
0:16:46 > 0:16:50They even have the energy to play.
0:16:50 > 0:16:51But their play has a purpose.
0:16:51 > 0:16:55It fine-tunes their hunting skills
0:16:55 > 0:16:59and helps bond the all-important pack structure.
0:16:59 > 0:17:03Though there are 16 of them they can only hunt
0:17:03 > 0:17:06an animal as large as an elk if they hunt as one.
0:17:12 > 0:17:17The strength of the pack is what will get them through the winter.
0:17:40 > 0:17:43Bald eagles spot carcasses from miles away.
0:17:46 > 0:17:50But there is strong competition for a kill like this.
0:18:14 > 0:18:16A coyote.
0:18:18 > 0:18:22He has been shadowing the wolves and moves in now they have gone.
0:19:17 > 0:19:18It's December
0:19:18 > 0:19:23and even the great Yellowstone River is succumbing to the cold.
0:19:25 > 0:19:29It's only where the water runs fast that it still runs free.
0:19:38 > 0:19:42It looks uncomfortably cold, but then the water
0:19:42 > 0:19:45at around freezing point can be 50 degrees warmer than the air.
0:19:48 > 0:19:52Under the ice there's a rich supply of stone fly larvae
0:19:52 > 0:19:54waiting to hatch in the spring.
0:19:56 > 0:19:58Dippers make the most of
0:19:58 > 0:20:02these few small windows to a liquid world before they shut completely.
0:20:15 > 0:20:20Where the water stands still it is now frozen solid.
0:20:22 > 0:20:27Yellowstone lake is 136 square miles
0:20:27 > 0:20:30and now completely covered in three feet of ice.
0:20:37 > 0:20:41A coyote travels across this frozen desert looking for something to eat.
0:20:45 > 0:20:48It's a wonder that anything can survive here at all.
0:20:50 > 0:20:53Hundreds of feet beneath him on the lake bed geysers erupt,
0:20:53 > 0:20:59just like they do on land, and they melt holes in the ice -
0:20:59 > 0:21:02the only sign that there is a lake here at all.
0:21:12 > 0:21:14As the year comes to an end,
0:21:14 > 0:21:19it seems hard to imagine this winter getting any tougher,
0:21:19 > 0:21:22but there's another twist to the volcano's story
0:21:22 > 0:21:25that is about to make things even worse.
0:21:30 > 0:21:34Over time, the continent of North America has moved,
0:21:34 > 0:21:40inch-by-inch, over many millions of years,
0:21:40 > 0:21:44but deep down below the Earth's moving crust, the source of magma
0:21:44 > 0:21:49that fuels Yellowstone's volcano has stayed put.
0:21:57 > 0:22:02As the crust has moved over this volcanic hotspot,
0:22:02 > 0:22:04eruption after eruption has
0:22:04 > 0:22:09blasted a massive 500 mile long scar right through the Rockies.
0:22:15 > 0:22:20In the winter this giant scar, called the Snake River Plain,
0:22:20 > 0:22:24funnels moist air from the Pacific Ocean right through the wall
0:22:24 > 0:22:29of the Rocky mountains and up into Yellowstone's deep freeze.
0:22:35 > 0:22:40Here it finally freezes and falls as snow,
0:22:40 > 0:22:43huge quantities of it.
0:22:59 > 0:23:04Whilst everywhere around gets ten feet of snow a year, thanks to the
0:23:04 > 0:23:08legacy of its volcano Yellowstone can get as much as 50.
0:23:18 > 0:23:21Otters seem to thrive in the Yellowstone winter.
0:23:31 > 0:23:36But now that the rivers are not only frozen but covered in deep snow
0:23:36 > 0:23:39they are struggling to find open water to fish in.
0:23:55 > 0:24:00They can't fish here, the fast flowing water is too dangerous.
0:24:00 > 0:24:03Somehow they need to find a way past the falls.
0:24:53 > 0:24:55With the falls safely behind them,
0:24:55 > 0:24:58the otters are forced to keep moving on.
0:25:02 > 0:25:06Open water has become a rare thing in Yellowstone.
0:25:16 > 0:25:20Out on the frozen grasslands, the bison are struggling too.
0:25:22 > 0:25:26This year is already the snowiest for the last decade,
0:25:26 > 0:25:30snowier than many of this herd have experienced in their lives.
0:25:32 > 0:25:35Now, as the snow gets deeper than a critical 4 feet,
0:25:35 > 0:25:37the effort of swinging this
0:25:37 > 0:25:42massive head back and forth for so little reward is becoming too much.
0:25:49 > 0:25:54Though the snow front is passing through, it's followed by the wind
0:25:54 > 0:25:58which now starts to scour the heart of Yellowstone.
0:26:20 > 0:26:24A bison's coat can keep it warm down to -30 degrees Fahrenheit.
0:26:28 > 0:26:32The wind chill is now pushing these bison to that limit.
0:26:43 > 0:26:47But these are the last wild bison herds in America,
0:26:47 > 0:26:51which have survived here for tens of thousands of years,
0:26:51 > 0:26:52they know what to do.
0:27:06 > 0:27:09To move is risky,
0:27:09 > 0:27:12it will tap into their now dwindling energy reserves.
0:27:14 > 0:27:17But this year it's a gamble worth taking.
0:27:25 > 0:27:29Their way out is a river whose water is not frozen.
0:27:29 > 0:27:35A thermal river fed by warm water from Yellowstone's geysers,
0:27:35 > 0:27:38an ancient route which leads to a place where,
0:27:38 > 0:27:42if they're lucky, they will be able to survive.
0:28:02 > 0:28:04It's January
0:28:04 > 0:28:08and night is twice as long as day in Yellowstone's deepfreeze.
0:28:10 > 0:28:12The wind and the storms have gone,
0:28:12 > 0:28:17but now the clear skies suck any last trace of heat into space.
0:28:20 > 0:28:24As morning comes something extraordinary has happened.
0:28:34 > 0:28:38All moisture in the air has turned to ice,
0:28:38 > 0:28:40diamond dust.
0:29:47 > 0:29:50But this is a cruel beauty.
0:29:50 > 0:29:55-66 Fahrenheit was recorded here in Yellowstone,
0:29:55 > 0:29:58off the record it gets colder still.
0:30:07 > 0:30:11This bison is still out on the open plateau,
0:30:11 > 0:30:14the deep snow with its wind blown crust has made it almost impossible
0:30:14 > 0:30:16to feed.
0:30:16 > 0:30:20The extreme cold will now tip the balance of survival further,
0:30:20 > 0:30:23most likely too far even for a bison.
0:30:43 > 0:30:48A red fox can stay in the cold heart of Yellowstone all winter,
0:30:48 > 0:30:50so long as it can find food.
0:30:55 > 0:30:56It's looking for mice that
0:30:56 > 0:31:00survive the winter insulated beneath the blanket of snow.
0:31:04 > 0:31:08The fox is light enough to move about on the delicate crust
0:31:08 > 0:31:10but the mice are six feet beneath it.
0:31:35 > 0:31:39It listens for the tiny sounds of its prey moving about below,
0:31:39 > 0:31:43but must take great care not to scare them away.
0:32:37 > 0:32:41The otter family has arrived at Yellowstone Lake.
0:32:41 > 0:32:46Here they can fish in the holes kept open by the underwater geysers.
0:32:55 > 0:32:57But every time they catch something...
0:33:00 > 0:33:03..This coyote has been watching and waiting.
0:33:03 > 0:33:05THEY SQUEAK
0:33:32 > 0:33:37The otter dives under the ice to hide its fish from the coyote.
0:33:44 > 0:33:48The coyote can't see the otter because of the thick cover of snow.
0:33:51 > 0:33:53But he can hear him.
0:34:01 > 0:34:04The otter emerges without the fish.
0:34:04 > 0:34:09He's stashed it somewhere under the snow. But where?
0:34:20 > 0:34:21CHIRPS
0:34:32 > 0:34:35A huge Yellowstone cut-throat trout.
0:34:39 > 0:34:44With the help of the otters, a wily coyote can catch fish too.
0:35:11 > 0:35:15The thermal river has led the bison to one of the main geyser fields.
0:35:20 > 0:35:23Here the heat from below comes close enough to the surface
0:35:23 > 0:35:25to melt the snow.
0:35:30 > 0:35:32And a bison can graze as if it were spring.
0:35:41 > 0:35:45The same volcanic forces, so massive
0:35:45 > 0:35:49that they created the weather that drove the bison here,
0:35:49 > 0:35:51now offer comfort.
0:35:58 > 0:36:03The only problem is, the grass that the bison now relish has such
0:36:03 > 0:36:08a high concentration of silica that it wears down their teeth
0:36:08 > 0:36:11and it's laced with enough arsenic to slowly poison them.
0:36:20 > 0:36:24For these bison it's not an easy choice to come here.
0:36:27 > 0:36:30But as long as they don't have to stay here too long,
0:36:30 > 0:36:33it's a lot better than facing the Yellowstone winter head on.
0:36:43 > 0:36:46Incredibly, there is life that thrives here.
0:36:48 > 0:36:50In Yellowstone's thermal springs
0:36:50 > 0:36:55the temperature is a constant near boiling.
0:36:55 > 0:36:59Yet here are huge colonies of heat tolerant microbes.
0:37:02 > 0:37:07As the boiling water flows out from the centre of springs,
0:37:07 > 0:37:12it cools, forming bands of different temperatures each with a different
0:37:12 > 0:37:15collection of microbes with a totally different colour.
0:37:21 > 0:37:25Grand Prismatic Spring is one of the wonders of the natural world.
0:37:29 > 0:37:32It's thought that it was in conditions like this
0:37:32 > 0:37:34that life on earth first started.
0:37:50 > 0:37:55It's now February and when almost everything else in Yellowstone
0:37:55 > 0:37:59is on its last legs the Druid pack is reaching peak condition.
0:38:02 > 0:38:06And it's now that the young females come into season.
0:38:09 > 0:38:13Hanging back from the pack is a lone male wolf.
0:38:16 > 0:38:19He has no territory of his own,
0:38:19 > 0:38:23but follows the pack, scavenging from their successes.
0:38:27 > 0:38:30But right now food is not his priority.
0:38:35 > 0:38:37The young females won't mate
0:38:37 > 0:38:40with the pack's alpha male as he is their father.
0:38:43 > 0:38:46So the intruder could well be in with a chance,
0:38:46 > 0:38:49as long as the alpha doesn't see him.
0:38:49 > 0:38:52WHINING
0:38:56 > 0:39:00Whilst the pack are distracted, one female sneaks away.
0:39:05 > 0:39:08She won't give up the security of the pack for him,
0:39:08 > 0:39:12so they meet close by in secret.
0:39:24 > 0:39:26But the pack are now coming their way.
0:39:42 > 0:39:44The alpha male is onto him.
0:39:48 > 0:39:50He won't tolerate
0:39:50 > 0:39:55any other male in his territory let alone with one of his females.
0:39:55 > 0:39:59When wolves mate they become locked together for up to half an hour,
0:39:59 > 0:40:03the intruder can't break free.
0:40:14 > 0:40:16BARKING
0:40:23 > 0:40:24BARKING AND HOWLING
0:40:42 > 0:40:47For now the alpha male has done enough, he's seen the intruder off
0:40:47 > 0:40:51and he needs to return to reassert his position in the pack.
0:40:58 > 0:41:02The intruder retreats to a precarious life in the shadows.
0:41:03 > 0:41:08But whatever happens to him, so long as he was coupled for long enough,
0:41:08 > 0:41:11he will have young brought up in the security
0:41:11 > 0:41:14of one of the strongest packs in Yellowstone.
0:41:25 > 0:41:27WOLVES HOWL
0:41:46 > 0:41:49THEY CALL
0:41:52 > 0:41:54Since the beginning of winter,
0:41:54 > 0:41:57Yellowstone's herds have been getting steadily weaker.
0:42:00 > 0:42:02Now at the end of February,
0:42:02 > 0:42:07the tables have completely turned to favour the Druid pack.
0:43:12 > 0:43:14WOLVES HOWL
0:43:18 > 0:43:23As February turns to March it seems like the winter will never end.
0:43:26 > 0:43:28But now the clear cold days have gone.
0:43:30 > 0:43:33The snow still comes, but it's a wet snow
0:43:33 > 0:43:36that strips the warmth from you faster.
0:43:39 > 0:43:43Now when you are right at the end of your strength.
0:43:54 > 0:43:55BIRD CALL
0:44:04 > 0:44:06But there is hope.
0:44:06 > 0:44:09Now is the turning point of the winter.
0:44:14 > 0:44:16At the spring equinox,
0:44:16 > 0:44:21there are twelve hours of night and twelve hours of day.
0:44:21 > 0:44:25From now on light starts to win over dark.
0:44:37 > 0:44:41March is also the turning point in the history of Yellowstone.
0:44:45 > 0:44:51On the first of March 1872 American President Ulysses S Grant
0:44:51 > 0:44:54recognised the extraordinary wonders of Yellowstone
0:44:54 > 0:44:58by making it the world's first national park.
0:45:16 > 0:45:19The park's creation marked the beginning of a new era
0:45:19 > 0:45:25where the world's wild places would be valued simply for being wild.
0:45:40 > 0:45:43GEESE HONK
0:45:51 > 0:45:52Now as the days lengthen,
0:45:52 > 0:45:56the winter starts to loosen its grip on Yellowstone.
0:46:04 > 0:46:08But with the end of winter also comes the end of the wolves' reign.
0:46:19 > 0:46:22On a mountain peak right on the edge of Yellowstone,
0:46:22 > 0:46:26footprints in the snow are the sign that a challenger has appeared
0:46:26 > 0:46:28to reclaim this land.
0:46:36 > 0:46:41A grizzly bear mother with her new cubs emerges from her den.
0:46:44 > 0:46:48For six months snow and ice have ravaged Yellowstone,
0:46:48 > 0:46:50but she has slept underground,
0:46:50 > 0:46:52waking only to give birth to her cubs
0:46:52 > 0:46:55and then from time to time to feed them.
0:47:04 > 0:47:06As winter gives way to spring,
0:47:06 > 0:47:09she leads them out into the wilderness for the first time.
0:47:16 > 0:47:19In Yellowstone's great volcano,
0:47:19 > 0:47:23in spite of everything the winter has thrown at them,
0:47:23 > 0:47:24most have made it through.
0:47:38 > 0:47:40The forces that have helped keep Yellowstone
0:47:40 > 0:47:44in the grip of such a deep winter have finally let go.
0:47:46 > 0:47:49It is the sun that will dominate once more.
0:47:56 > 0:47:59Its power will now take over.
0:48:05 > 0:48:08Bringing new life to this place.
0:48:21 > 0:48:24But also it will bring new challenges...
0:48:24 > 0:48:27..that all will have to face...
0:48:29 > 0:48:33..In the heat of Yellowstone's summer.
0:48:47 > 0:48:51Bringing Yellowstone's unique natural beauty to the screen
0:48:51 > 0:48:53would have been impossible without the tireless
0:48:53 > 0:48:58help of the local experts that know it like the back of their hand.
0:48:58 > 0:49:00Each has their own story to tell.
0:49:00 > 0:49:04I was born in the night of a blizzard and my mother has always told me that
0:49:04 > 0:49:06she thinks that's why I'm so in love with winter.
0:49:10 > 0:49:12Ex-park-ranger and photographer
0:49:12 > 0:49:16Jeff Henry's thirty years of experience in Yellowstone
0:49:16 > 0:49:21helped the BBC crew unlock some of the national park's hidden secrets.
0:49:23 > 0:49:26But they could never get hold of Jeff once the snow started to fall.
0:49:29 > 0:49:32Winter's by far my favourite season,
0:49:32 > 0:49:36I wish I could be the reverse of a bear and hibernate in the summer,
0:49:36 > 0:49:38and just wake up in the autumn
0:49:38 > 0:49:40and be looking at a new winter.
0:49:41 > 0:49:45I get really excited when the first snows come in the autumn.
0:49:46 > 0:49:51Snow to me is a mystical, magical substance.
0:49:51 > 0:49:53I've always thought that it's very
0:49:53 > 0:49:57coarse of the English language to have just one word for it,
0:49:57 > 0:49:58there's snow and then there's snow,
0:49:58 > 0:50:00and then there's snow and then there's snow.
0:50:00 > 0:50:03Fresh snow that falls from the sky, and here in Yellowstone
0:50:03 > 0:50:06it tends to be light and fluffy, is vastly different
0:50:06 > 0:50:10from the snow that's been on the ground for three or four months.
0:50:14 > 0:50:18Three million tourists travel each year to enjoy Yellowstone's
0:50:18 > 0:50:20spectacular wilderness.
0:50:20 > 0:50:24When winter arrives, however, the crowds disappear.
0:50:28 > 0:50:32But for the last thirty years Jeff has enjoyed a very unusual way
0:50:32 > 0:50:38of both staying for the winter and indulging his love of snow.
0:50:38 > 0:50:41His task is to stop the few buildings
0:50:41 > 0:50:45in the heart of Yellowstone being completely swallowed.
0:50:47 > 0:50:50Jeff becomes what is officially known as a roof shoveller.
0:50:52 > 0:50:54The reason I do that is the snow loads can
0:50:54 > 0:50:58sometimes at least some years become so heavy they can crush buildings
0:50:58 > 0:51:00or break parts of buildings.
0:51:02 > 0:51:06Jeff must clear up to three metres of compacted snow from the roofs
0:51:06 > 0:51:11before it falls on anything wandering beneath including himself.
0:51:11 > 0:51:14If the building were to avalanche on top of me,
0:51:14 > 0:51:15it would be the end of the line for me.
0:51:18 > 0:51:21From December onwards Jeff spends five months clearing
0:51:21 > 0:51:24snow off Yellowstone's roofs.
0:51:24 > 0:51:25Timing is critical.
0:51:25 > 0:51:27If he starts a roof too early,
0:51:27 > 0:51:30fresh spring snow will undo all his hard work,
0:51:30 > 0:51:33too late and the roof may collapse.
0:51:38 > 0:51:41This particular roof has a pitch
0:51:41 > 0:51:46that's steep enough that the snow will avalanche off if it's undercut.
0:51:46 > 0:51:49And to undercut the snow I have to first
0:51:49 > 0:51:52dig some channels or trenches with a shovel.
0:51:55 > 0:52:01After I've cut those channels I can lay a steel cable into each trench.
0:52:01 > 0:52:05And I pass that cable underneath the snow pack, between the snow pack
0:52:05 > 0:52:06and the shingles.
0:52:06 > 0:52:10And after the snow is undercut it will avalanche off.
0:52:22 > 0:52:26Oh, I have to admit I get a tremendous kick out of the work.
0:52:26 > 0:52:29Little me at 190 pounds can move
0:52:29 > 0:52:31untold tonnes of snow in one swoop.
0:52:39 > 0:52:42Jeff is especially drawn to what are know as cornices,
0:52:42 > 0:52:46the overhanging shelves of snow that cling to the edges of roofs.
0:52:46 > 0:52:48It's kind of a love-hate relationship.
0:52:51 > 0:52:55This lovely pattern, there's lovely lines in the snow, you can see the
0:52:55 > 0:52:58major lines between major wind events but you can see
0:52:58 > 0:53:02more minor lines. I guess. between more minor wind events,
0:53:02 > 0:53:05it's almost like the growth rings on a tree.
0:53:05 > 0:53:08It's just absolutely beautiful.
0:53:08 > 0:53:12Fascinating. I can't wait to get up there and destroy it.
0:53:14 > 0:53:18Cornices are especially threatening structurally,
0:53:18 > 0:53:20because there's so much weight
0:53:20 > 0:53:22hanging out over the edge of the building.
0:53:22 > 0:53:26It's not uncommon for an eaves to break when it has a big overhang.
0:53:26 > 0:53:28Ah! LAUGHS
0:53:33 > 0:53:36I love to do this work, I love to move snow,
0:53:36 > 0:53:40it's a thrill, it's exciting, it's fun.
0:53:40 > 0:53:42Ah, ah ha.
0:53:42 > 0:53:45Honestly, there's no place else I'd rather be.
0:53:47 > 0:53:50But there's one building that's a real challenge for Jeff.
0:53:50 > 0:53:52The Canyon General store is approximately
0:53:52 > 0:53:5550 years old, 52 years old something
0:53:55 > 0:53:59in that range, and I've cleared this building for about half of its life.
0:53:59 > 0:54:02It's by far the largest building that I have to do.
0:54:02 > 0:54:05I often joke that it is the Bismarck of the enemy fleet.
0:54:08 > 0:54:11It takes me a great many working days,
0:54:11 > 0:54:15as many as 40 or 50 working days per winter.
0:54:19 > 0:54:23This roof collects more snow than any other in the park,
0:54:23 > 0:54:26instead of using gravity to remove the compacted snow
0:54:26 > 0:54:28Jeff has to rely on sweat and toil.
0:54:32 > 0:54:35But he's perfected his own methodical, precision,
0:54:35 > 0:54:37labour-saving technique.
0:54:41 > 0:54:45Well, I try to cut the blocks large enough so that they'll be stable
0:54:45 > 0:54:47when I move them across the roof,
0:54:47 > 0:54:51but not so large that I can't move them.
0:54:53 > 0:54:57On this particular building this year there'll be somewhere in the order
0:54:57 > 0:55:02of 3,000 blocks of snow, so I always reason that if I could
0:55:02 > 0:55:06save just 1% or 2% of the effort that it takes to move each block
0:55:06 > 0:55:11that would be 1% or 2% times 3,000.
0:55:14 > 0:55:17That's why I work in this chequerboard pattern
0:55:17 > 0:55:21and move all the blocks that I just cut and I don't have to go back and
0:55:21 > 0:55:24forth between the saw and the shovel that often.
0:55:24 > 0:55:26I suppose in some ways
0:55:26 > 0:55:31analogous to Yellowstone's wildlife in the winter
0:55:31 > 0:55:33where they have to be so mindful
0:55:33 > 0:55:37of their energy equation they, they cannot
0:55:37 > 0:55:40consistently expend more energy than they take in.
0:55:42 > 0:55:46And if they do, it's the end of the line.
0:55:53 > 0:55:5750 days spent alone on a roof gives Jeff a lot of time
0:55:57 > 0:55:59to just think.
0:56:00 > 0:56:05Sometimes I find my imagination runs away with me, I think about how,
0:56:05 > 0:56:08this snow not very long ago was
0:56:08 > 0:56:10warm sea water
0:56:10 > 0:56:12in the South Pacific Ocean.
0:56:12 > 0:56:16In just over three or four months,
0:56:16 > 0:56:19it will be water vapour
0:56:19 > 0:56:22or liquid water seeping into the earth
0:56:22 > 0:56:25here in Yellowstone or flowing down the Yellowstone river.
0:56:25 > 0:56:29Jeff's snow-clearing work allows him
0:56:29 > 0:56:33to be in the most beautiful parts of the park when no-one else is around.
0:56:34 > 0:56:38And I think everybody appreciates
0:56:38 > 0:56:41a little bit of solitude.
0:56:41 > 0:56:43I guess that's part of the reason I do the work I do
0:56:43 > 0:56:47and spend as much time as I can. in the park in the winter.
0:56:47 > 0:56:49Occasionally it just seems to me
0:56:49 > 0:56:52that I'm the only person for miles around and that's a special
0:56:52 > 0:56:55feeling especially in the early 21st Century.
0:56:57 > 0:56:59I know my parents first brought me here
0:56:59 > 0:57:03when I was six months old and essentially I've spent my entire
0:57:03 > 0:57:04adult life here in Yellowstone.
0:57:04 > 0:57:08I don't know if I believe in destiny in the general sense but I do believe
0:57:08 > 0:57:11it was my destiny to come here and to spend most of my life here.
0:57:12 > 0:57:15Because of the work I do in the winter here I've had
0:57:15 > 0:57:19a special opportunity, I think, to make empirical observations about
0:57:19 > 0:57:22the way things have gone in terms of winter weather in Yellowstone.
0:57:22 > 0:57:25I don't think there's any question that things are
0:57:25 > 0:57:29warmer and drier overall than they were when I first got here.
0:57:29 > 0:57:35I've always been dreading the day when I got too old to do this,
0:57:35 > 0:57:37but over the last ten years or so it seemed that,
0:57:37 > 0:57:41maybe Yellowstone would run out of snow before I got too old to move it.
0:57:41 > 0:57:44There's good snow this year so I certainly hope it continues,
0:57:44 > 0:57:46certainly hope there's snow to move in Yellowstone
0:57:46 > 0:57:49long after I'm not able to do it any more.
0:57:49 > 0:57:51We'll see I guess.
0:57:54 > 0:57:58I like the challenge when I first climb up onto the roof and take that
0:57:58 > 0:58:01first block of snow off and then when I take the last block off a roof
0:58:01 > 0:58:04I certainly feel a sense of satisfaction.
0:58:04 > 0:58:07I also immediately start thinking about next season when I'll be able
0:58:07 > 0:58:09to do the same building again.
0:58:11 > 0:58:14Yellowstone will always be my special place.
0:58:35 > 0:58:36Subtitles by Red Bee Media Ltd
0:58:36 > 0:58:38E-mail subtitling@bbc.co.uk