[00:27.84]Vast open plains.
[00:39.71]but any feeling of emptiness is an illusion.
[00:46.64]The plains of our planet
[00:48.22]support the greatest gatherings of wildlife on Earth.
[00:56.92]At the heart of all that happens here
[00:59.31]is a single living thing.
[01:08.30]This miraculous plant covers a quarter of all the lands of the Earth.
[01:30.54]where ever there is a little rain, but not enough to sustain the forests.
[01:36.06]Some are huge.
[01:38.42]The Central Asian Steppe alone
[01:40.52]extends one third of the way around our planet.
[01:51.08]and eagles effortlessly cruise the thermals
[01:54.32]scanning the ground beneath for signs of prey.
[02:00.21]In the distant reaches of Outer Mongolia
[02:02.99]one of the planet's great migrations is underway.
[02:12.98]Few people ever see this extraordinary annual event.
[02:27.65]Two million are thought to live here but no one really knows.
[02:34.83]For much of the time they're scattered through this vast landscape
[02:38.80]but once a year they come together to have their young.
[02:44.02]Nearly all will give birth within the next ten days.
[02:53.05]Out in the open, communal calving is the safest way to have young.
[02:58.10]With so many pairs of eyes keeping watch
[03:00.37]it's almost impossible for predators to sneak up.
[03:10.01]There are no bushes, no trees, there's only one thing to hide behind,
[03:18.79]and it's not very effective.
[03:28.69]Predators also have a hard time raising their young on open grassland.
[03:33.79]Without trees eagles have to nest directly on the ground.
[03:41.14]All inhabitants of the Great Plains are exposed to the elements.
[04:03.44]Fire sparks panic in the herd.
[04:13.08]Gazelles are born to run, and even young calves easily outpace the flames
[04:18.65]if they can avoid being trampled.
[04:54.57]With nothing to stand in it's way the blaze consumes anything that can't flee.
[05:01.34]Huge quantities of grass, valuable food have been lost
[05:10.26]and with it the old and the weak.
[05:18.50]The gazelles move on to new pastures and leave the desolation behind them.
[05:27.47]From the ashes rises the phoenix.
[05:31.37]Grass the incredible survivor.
[05:37.50]Because it grows from a protected part at the base of its stems,
[05:41.71]grass is almost indestructible.
[05:55.56]Able to repair and reproduce itself rapidly
[05:58.77]it covers more of the Earth's land than any other plant
[06:02.56]and feeds more wildlife than any other.
[06:25.83]Red billed quelea.
[06:28.11]One and a half billion swarm across the savannas of Africa.
[06:32.37]These are the most numerous birds on Earth.
[06:40.52]Some flocks are so vast, that they could take five hours to pass overhead.
[07:18.95]Only grass can feed plagues of these proportions.
[07:23.74]The ravenous hordes devour the seeds
[07:27.87]and the leaves and stems are cropped by great herds of antelope.
[07:43.34]The East African savannas alone sustain nearly two million wildebeest.
[08:01.17]They trim the grass down to it's roots leaving little in their wake
[08:05.81]but within days the plant will recover and continue to sustain the biggest herds on Earth.
[08:23.79]Grass is not confined to the tropics.
[08:31.54]It manages to grow even in the bitter conditions of the Arctic.
[08:44.00]Beyond the limits of the last tree the planet is barren and ice locked.
[08:50.11]The frozen no man's land at the end of the Earth.
[08:54.55]But, for a short time each year, the long dark winter releases it's grip.
[09:12.09]Temperatures rise, and grass that has lain dormant and frozen throughout the winter
[09:17.53]sprouts once more.
[09:24.45]Green returns to the Arctic.
[09:28.71]The receding ice reveals an immense flat plain, the size of Australia.
[09:34.35]This is the Arctic tundra.
[09:43.59]It's a desolate silent wilderness
[09:46.97]but it's about to change.
[10:09.65]They winter along the Gulf of Mexico
[10:12.21]and in spring they fly the entire length of North America to reach the Arctic tundra.
[10:19.63]Five million birds make this journey every year.
[10:39.86]Their marathon migration is almost three thousand miles long
[10:44.27]and has taken them three months.
[10:53.25]Exhausted and starving, they touch down inside the Arctic Circle
[10:58.38]back at their traditional breeding grounds, at last.
[11:04.02]Snow geese pair for life.
[11:06.46]As soon as couples arrive, they must stake a claim to a nesting patch.
[11:15.13]Ideal sites are in short supply and quarrelsome neighbors are all around.
[11:24.24]Disputes can be vicious.
[12:03.66]It's a long way to travel, but for a short period the tundra is the ideal place for a grazer.
[12:10.41]The grass grows vigorously during the short intense summer
[12:13.95]and the are fewer predators than farther south.
[12:21.21]Here, geese can nest on the ground in relative safety
[12:25.41]nonetheless this female must incubate her eggs for three weeks
[12:29.49]and throughout this time she will be very vulnerable.
[12:46.81]An Arctic fox surveys the colony.
[12:49.78]She's been waiting for the geese all winter.
[12:58.12]Sneaking up unnoticed is impossible.
[13:10.84]Perhaps fortune will favor the bold.
[13:28.49]The colony is well defended. There are no easy pickings here.
[13:44.08]She's driven away from every nest, but hunger compels her to continue.
[14:16.82]There are more eggs here than she can possibly eat now
[14:20.33]but the nesting season is short
[14:23.14]so she stashes much of her plunder for later in the year
[14:26.58]when all the geese have gone.
[14:40.21]Further south, other bigger predators prowl the tundra.
[14:48.58]For them, finding food on the plains is an even greater challenge.
[14:53.18]Not only is their prey seasonal it's also hard to find.
[14:56.91]They've been searching for days without a sign.
[15:06.99]Somewhere in this immense landscape there is food for them.
[15:18.56]This is it. Caribou.
[15:23.26]Travelling thirty miles a day
[15:25.35]they can cover nearly two thousand miles during the summer months.
[15:37.68]The wolves will starve if they don't find the caribou
[15:41.40]but it's no easy task to locate prey that never stops traveling.
[16:06.23]Biting flies and the quest for new pasture
[16:09.25]drives the migration ever onwards.
[16:47.73]A wolf has finally picked up the trail.
[16:52.49]The caribou are close.
[16:59.18]At last, a chance.
[17:04.42]The hunt is on.
[17:17.20]The wolf panics the herd, and the weak and young are singled out.
[17:30.14]A calf is separated from it's mother.
[18:09.54]At the goose colony it's high summer and eggs are hatching.
[18:16.57]The young all emerge within a day or two. A marvel of timing.
[18:21.07]The colony is now home to a million goslings.
[18:40.83]The fox is still gathering all she can get.
[18:48.93]Sometimes one mouth simply isn't enough.
[19:26.89]One will have to do.
[19:35.13]Not all food is stored.
[19:37.37]Some is needed right now.
[19:41.21]She has seven hungry cubs to feed.
[19:50.61]As their appetites grow, the mother must work tirelessly to raise her family.
[19:55.51]Only fat healthy cubs will survive the Arctic winter.
[20:15.11]The vast majority of the goslings are still flourishing.
[20:19.05]Their parents lead them down to the safety of the water
[20:22.07]as soon as they're strong enough to make the journey.
[20:30.64]For the foxes boom time has come to an end
[20:34.71]but the mother has given her cubs the best possible start in life.
[20:41.77]The geese will continue grazing the tundra
[20:44.37]until the summer ends, and they're forced to head south for the winter.
[20:56.85]At these latitudes the Sun's rays are week
[20:59.97]and grass can only grow here for a few months a year
[21:03.41]but further south summers are longer and the grasslands flourish.
[21:22.80]The prairies of North America.
[21:27.52]This rich pasture once supported the greatest herds ever seen on our planet.
[21:43.20]There were once sixty million bison
[21:46.00]but no animal is immune to intensive hunting by man
[21:49.73]or the destruction of it's habitat
[21:52.25]and a century ago the bison were reduced to barely a thousand.
[21:57.87]Now, thanks to rigorous protection, the species is recovering.
[22:07.67]The growing season is long
[22:09.70]and the grass here can support herds all year around.
[22:19.29]Male bison weigh in at one ton.
[22:38.33]In high summer the bulls are fat from the rich grazing
[22:41.73]and in prime condition but only a few will mate.
[22:45.29]Exactly which few is about to be decided.
[23:19.82]On temperate plains around the world summer is a time for growth and reproduction.
[23:28.89]Now the grass produces it's flowers.
[23:44.56]New colors also come to the plains.
[24:24.24]The northern flowering is mirrored by the grasslands of the southern hemisphere.
[24:29.99]And nowhere is more impressive than on the velt of South Africa.
[25:21.39]Not all temperate plains are so rich and colorful in the summer.
[25:33.93]This is midsummer on the Tibetan Plateau
[25:37.60]the highest great plain in the world.
[25:41.96]Despite the conditions, grass survives, and in sufficient quantities
[25:46.34]to support the highest of all grazing herds
[25:49.98]those of the wild yak.
[25:55.22]Even in summer life is hard
[25:58.01]temperatures rarely rise above freezing, and the air is thin.
[26:09.14]It's also exceptionally dry for one very big reason
[26:21.57]The great mountain range acts as a barrier
[26:24.67]preventing clouds moving in from the south
[26:27.41]and this casts a giant rain shadow that leaves Tibet high and dry.
[26:51.18]Grass clings to life
[26:53.51]even as desiccating winds remove what little moisture remains in the soil.
[27:08.20]So long as grass can survive, so can grazers.
[27:27.92]The males are fighting to win territories
[27:30.84]those that hold the best, are more likely to attract a herd of females.
[27:51.39]It's a frisky business.
[27:58.69]That counts as a victory
[28:00.55]but he can't assume the females will actually turn up.
[28:09.03]Female asses are mysterious creatures.
[28:15.01]They come and go as they please and much of their behavior seems unfathomable
[28:20.28]to an outsider.
[28:33.22]They're the great nomads of the plateau
[28:35.86]and will often trek vast distances across these parched plains in search of oases.
[28:43.71]But when they do find paradise
[28:46.09]they're liable to feed and drink for just a few hours
[28:49.50]and then head back to the dust for no apparent reason.
[28:58.17]Wild ass are the most conspicuous pioneers of this high frontier
[29:03.34]but the most numerous grazer in Tibet lives underground.
[29:12.40]A relative of the rabbit. It too feeds on grass.
[29:21.94]On the exposed plateau
[29:24.12]pikas never stray far from their burrows
[29:26.95]but even so, squatters will move in given half a chance.
[29:44.53]While ground peckers and snow finches can be a nuisance
[29:48.48]they're worth tolerating,because they provide a valuable early warning system.
[30:06.92]The bizarre Tibetan fox. The pika's nemesis.
[30:34.82]When stalking, it keeps below the skyline
[30:38.73]perhaps helped by it's curious body shape.
[30:42.85]But why the square head?
[31:36.72]In summer, the Tibetan plateau heats up
[31:40.15]drawing in warm wet air from the south
[31:43.40]but the water never arrives.
[31:46.08]As the moist air approaches it's forced upwards by the Himalayas
[31:50.28]and condenses into huge rain clouds.
[32:08.11]These clouds drop all their water on the southern side of the mountains.
[32:13.25]The very peaks that keep Tibet dry
[32:15.94]are responsible for the monsoon rains falling farther south, and the greening of India.
[32:31.94]Here, soaked by rain and bathed in tropical sun
[32:35.76]grass reaches it's full potential.
[32:41.16]Elephant grass is the tallest in the world.
[32:57.00]Grass that towers over an elephant, can conceal all sorts of surprises.
[33:11.34]The male lesser florican.
[33:13.80]It's hard work getting noticed when you go courting in the high grass.
[33:32.21]The long grass plains of tropical India are home to some of the largest
[33:36.66]grass eating mammals on our planet...
[33:39.53]and some of the smallest.
[33:43.82]Pygmy hogs are no bigger than rabbits.
[33:46.86]They're the tiniest and rarest of all wild pigs.
[33:55.54]The female is busy collecting grass but not for eating.
[34:07.99]She's building a nest.
[34:24.22]Each piglet may be small enough to fit in the palm of a hand
[34:28.61]but she does have ten.
[34:44.42]This is how grass can grow given unlimited sunshine and water
[34:50.27]but on most tropical plains across our planet
[34:53.37]the wet season is followed by a dry one.
[35:06.40]On the African savannas, grazers are marching in search of grass and water.
[35:33.07]Without rain, these plains can become dust bowls. Grass can now loose it's hold.
[35:49.63]Elephants are in immediate danger.
[35:52.42]They must drink almost daily.
[36:00.69]Driven on by thirst, they march hundreds of miles across the parched plains.
[36:24.29]Relying on memory, the matriarchs lead their families to those special water holes
[36:30.59]that saved them in previous years.
[36:39.70]This one still has water
[36:42.18]but they must share what remains with desperately thirsty animals of all kinds.
[37:05.02]These are tense times.
[37:23.78]The elephants dominate the water hole
[37:26.63]but as night falls the balance of power will shift.
[37:43.64]Thirsty herds continue to arrive throughout the night.
[37:47.97]It's a cooler time to travel.
[38:10.34]In the darkness the tables turn.
[38:17.44]The elephant's night vision is little better than our own
[38:24.42]but lions have much more sensitive eyes.
[38:41.14]The cats are hungry and the elephants seem to sense it.
[39:24.77]Lions don't usually hunt elephants, but desperate times require desperate measures.
[39:32.54]This herd contains calves easier targets.
[39:41.16]But how to reach them?
[39:58.44]The adults encircle their young.
[40:00.77]It's an impenetrable wall of grey.
[40:31.48]A few exhausted stragglers are still arriving.
[40:39.25]One of them is alone.
[41:01.21]But it's too big for the lions to tackle.
[41:09.90]This one looks a little smaller.
[41:25.42]A solitary lion stands no chance
[41:29.50]but the whole pride is here.
[41:35.35]There are thirty of them, and they're specialist elephant hunters.
[42:45.18]This elephant will feed the whole pride for at least a week.
[42:59.83]Elephants know these drinking holes are dangerous, but they have no choice.
[43:06.14]The dramas that play out here are a savage reminder
[43:10.14]of how important water is for all life on these plains.
[43:23.50]As the dry season finally draws to a close
[43:26.89]Africa's baked savannas undergo a radical change.
[43:33.48]Rain sweeps across the continent and grass, the great survivor, rises again
[43:40.79]and the herds return.
[43:45.67]For months they've been scattered over huge areas, clinging to existence around tiny water holes.
[43:53.00]Now, the good times are back.
[44:01.72]A few African savannas are very special.
[44:05.80]Here, rain water from far and wide flows across the flat plains.
[44:11.88]Grass is submerged but still it grows.
[44:36.07]Flooded, burnt, baked and frozen grass can withstand it all.
[44:47.58]After six months of drought, grass replaces dust over great areas.
[45:04.05]Fresh new shoots draw animals from great distances.
[45:19.95]Many undertake epic migrations to catch the boom time.
[45:32.47]Some resourceful animals live here all the year round.
[45:44.37]Baboons are permanent residents but they have to change their behavior
[45:48.99]if they are to gather what they need on the newly flooded plains.
[45:58.12]There's plenty to eat but getting to it can be a little uncomfortable.
[46:52.47]New water poses problems for the youngsters
[46:56.40]but they know where to find a dry seat.
[47:08.74]A juicy snail is ample recompense for sodden paws.
[47:24.90]Having survived the dry barren times animals can now reap the rewards.
[47:37.29]On this seasonal planet, the great plains are lands of feast and famine.
[47:44.16]At their peak they support the greatest gatherings of wildlife
[47:48.39]found anywhere on Earth.
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