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00:00Nuestro planeta es el más grande puzzle de viviendo en el universo.
00:05Un colección de mundos dentro de mundos.
00:09Cada uno un ecosistema de un ecosistema de la vida de la vida.
00:17Pero cómo funcionan?
00:20El intercambio web de relaciones y la influencia de las fuerzas naturales
00:26makes each micro-world complex and unique.
00:33So, to discover their secrets, we need to explore them one by one.
00:40Untangle their interlocking pieces.
00:43And ultimately reveal the vital piece.
00:47The key to life itself.
00:50Hidden deep within each of nature's micro-worlds.
00:56On a plateau high in the rocky mountains of North America
01:08sits an iconic wilderness.
01:12Yellowstone National Park.
01:22Cataclysmic forces have shaped this natural wonder.
01:25Its unique geology means that volcanic heat from the Earth's core
01:29comes right to the surface.
01:35It is the most extensive geothermal area on Earth.
01:40With more than 10,000 thermal wonders.
01:43Established in 1872, Yellowstone is the world's first national park.
01:52Covering more than 8,000 square kilometres.
01:57Aside from its awe-inspiring landscape,
01:59it's home to an array of North America's most charismatic wildlife.
02:03These dwell in vast forests and grasslands,
02:14as well as rivers and wetlands.
02:18Isolated by sheer mountain peaks,
02:21this stunning micro-world is a stage
02:23upon which scientists discovered surprising connections
02:27between different species.
02:31To fully understand the key to the rich complexity of life in Yellowstone today,
02:36we must look at how the presence of one animal
02:38can affect that of another.
02:40At the very top of the food chain in Yellowstone
02:44is an iconic predator.
02:47The wolf.
02:51The park is currently home to 98 wolves in 10 packs.
02:56These survive by hunting the herds of large grazing mammals.
03:00At the other end of the spectrum is a humble tree-felling rodent.
03:12The beaver.
03:14On the face of it, wolves and beavers live very independent lives.
03:19And there appears to be no connection between them.
03:22So it came as a surprise to find that their fates
03:24were somehow intertwined.
03:26This was discovered after the National Parks and Wildlife Service
03:31launched a landmark project
03:33to return wolves to Yellowstone.
03:39Wolves were absent from the park for 70 years.
03:45They were eradicated as part of a predator control campaign
03:48aimed at protecting livestock.
03:50But in 1995, 31 wolves were released
03:58in a last-ditch effort
03:59to save the species from extinction in the wild.
04:07The releases were surrounded with controversy.
04:11Some parties claimed that wolves would unleash devastation
04:14upon valuable stocks of America's rare grazing mammals.
04:17Somebody knock it on my door.
04:22What was to happen was even more remarkable.
04:29Soon after the reintroduction of wolves,
04:32Yellowstone's rivers took a turn for the better.
04:37Flows improved, fish spawned more successfully,
04:40and numbers of water birds increased.
04:49This improvement in river habitat
04:51was down to the tireless work of beavers.
04:57Beaver dams are key to rich wetlands.
05:00As well as providing habitat for fish,
05:02birds and other animals,
05:04their precious reserves of water
05:06improve flows through the dry summers
05:08and remove sediments.
05:15The timing of the beaver's return
05:17was too closely linked with that of the wolf
05:19to be a coincidence.
05:22So what is the link
05:23between wolves and beavers?
05:26How are their lives interconnected?
05:28How are their lives interconnected?
05:40Before we answer these questions,
05:42let's take a look at what makes a wolf pack
05:44a force to be reckoned with.
05:53Winter is the wolf's time.
05:54The relentless cold weakens their prey.
06:01Even so, this elk is a formidable quarry,
06:05standing one meter and a half at the shoulder
06:07and weighing over 300 kilos.
06:10A wolf in comparison only weighs about 50 kilos.
06:13But wolves, as well as being highly intelligent,
06:15have the advantage of numbers and teamwork.
06:20The odds are stacked in their favor.
06:24Despite the wolf's apparent advantage,
06:31the elk is in his prime
06:33and is smart.
06:35He knows that wolves will not risk
06:37following him into the freezing water.
06:40Crossing the river,
06:41he makes good his escape
06:42to the disappointment of the pack.
06:46A wolf pack is a close family unit.
06:55It's led by a dominant pair of breeding wolves
06:58known as the alpha pair.
07:02As a general rule,
07:04the other pack members
07:05consist of their siblings and offspring.
07:07In a pack,
07:12only the alpha male and female
07:14are allowed to breed.
07:16The function of the rest of the pack
07:17is only to help in hunting
07:19and looking after young.
07:21But it doesn't stop them all playing together.
07:29Pack hierarchy is maintained
07:31through these ritualized play fights.
07:34Rank is based on attitude
07:35rather than size
07:36or physical strength.
07:39And there is one other way
07:41through which they strengthen their bond.
07:43Howling is used as a means
07:55of long-distance communication.
07:58It maintains cohesion within the pack
08:01even if they're separated.
08:03And most importantly,
08:04it advertises their presence,
08:07making a stamp on the territory
08:08and letting other wolf packs
08:11know where their boundaries lie.
08:13Apart from the fact
08:18that beavers exist
08:19within wolf territory,
08:21they have little to do with them.
08:23Why then
08:24have their numbers increased?
08:28First, we need to look
08:30at what Yellowstone was like
08:31before the wolves were brought back.
08:40Before 1995,
08:42Yellowstone's top dog
08:43was a close cousin
08:44to the wolf.
08:49The coyote.
08:53Before wolves returned,
08:55Yellowstone had the largest coyote population
08:57in North America.
08:59This had a profound impact
09:01on the ecosystem.
09:04Weighing in at 12 kilos,
09:06Yellowstone's coyotes
09:07are less than half the size
09:08of the wolves
09:09and are not built
09:10to tackle big prey.
09:15They exist mainly on a diet
09:17of small animals.
09:19Vols and ground squirrels
09:20are high on their menu.
09:27They're also scavengers.
09:28Winter casualties
09:30are a welcome feast.
09:31For bald eagles,
09:42winter carrion
09:43is a welcome addition
09:44to their diet.
09:46But during the reign
09:46of the coyote,
09:47they were up against
09:48serious competition.
09:52Thievery is another coyote trait.
09:54These otters have hidden
09:59their hard-earned winter catch
10:00in a burrow
10:01under deep snow.
10:03But it doesn't go unnoticed.
10:07The coyote's excellent sense of smell
10:09leads it to the prize.
10:10They don't call coyotes
10:14wily for nothing.
10:16In the absence of wolves,
10:18coyotes moved around
10:19in the open without fear.
10:22This fearlessness
10:23had a devastating impact
10:25on the wider ecosystem
10:26and especially
10:28on one of Yellowstone's
10:29rarest mammals.
10:32The pronghorn antelope.
10:33The pronghorn is the only
10:41surviving member
10:41of an ancient group of animals
10:43that arose in North America
10:4420 million years ago.
10:47They're quite small,
10:49standing about a metre
10:50at the shoulder.
10:52But what they lack in height,
10:53they make up for
10:54in speed.
10:58They're able to maintain speeds
11:00of over 70 kilometres an hour
11:02for long periods.
11:03Coyotes are not big
11:06or fast enough
11:07to take down
11:08an adult pronghorn,
11:09but they do have a taste
11:10for their calves.
11:13Before wolves returned,
11:15the average life expectancy
11:16of a pronghorn fawn
11:17was just 35 days.
11:21Coyotes swept through the herds,
11:23taking calves,
11:24and the pronghorn population
11:25fell to dangerously low levels.
11:28By the early 1990s,
11:30there was serious concern
11:31for the pronghorn.
11:33But all that was to change.
11:36When the wolf returned,
11:37coyotes were dealt
11:38a shocking blow.
11:40Through systematic killing
11:41and direct competition,
11:44wolves showed the coyote
11:45who was boss.
11:51With coyotes firmly
11:52back in their place,
11:53pronghorns have been given a respite.
11:57Wolves pay little attention to them.
12:00The adults are too fast,
12:02and the young are not substantial
12:03enough to feed a pack.
12:05So wolves set their sights
12:07on bigger prey.
12:09This peculiar symbiosis
12:11has seen pronghorn numbers
12:13increase over the wolf's range.
12:15Coyote populations on the other hand
12:19have fallen to a fraction
12:20of what they were before,
12:21a more natural level.
12:24These days, coyotes have reverted back
12:27to being more secretive and nervous.
12:29They have to look over their shoulder
12:31at every turn.
12:32So by policing the coyotes,
12:42wolves have unwittingly benefited
12:44the pronghorn,
12:46redressing a balance.
12:48An unforeseen consequence
12:50of the reintroduction program.
12:53Were coyotes also the reason
12:55why beavers were absent
12:56in Yellowstone?
12:57Do beavers feature
13:01in a coyote's diet?
13:04Beavers don't live
13:06in the dam itself,
13:07but within a nearby mound
13:08built from the same material
13:09known as a lodge.
13:12The lodge can only be accessed
13:13via an underwater entrance.
13:16Inside, safe from the attention
13:18of predators,
13:19they can rear their young.
13:21With all this protection,
13:23it's very unlikely
13:24they'd ever encounter a coyote.
13:27So coyotes are not the link
13:29between wolves
13:30and the recent success
13:32of the beaver.
13:33But there is one Yellowstone predator
13:36that is comfortable in the water
13:37and has been known
13:39to prey upon beavers.
13:43The bear.
13:47There are up to 150 grizzly bears
13:49in Yellowstone.
13:51Big males weigh almost 300 kilos.
13:55They're without a doubt
13:55the largest predator here.
13:58So what is the grizzly's relationship
14:00with the wolf?
14:01And has this had an impact
14:03on the beaver?
14:09Bears are omnivores,
14:11feeding on a diet of berries,
14:12nuts and herbs,
14:13as well as scavenging
14:14and hunting other animals.
14:17They will sometimes dig open
14:20beaver lodges
14:20and prey upon beavers.
14:24If they really need meat,
14:26they're more than capable
14:27of chasing big prey,
14:28like elk.
14:39Despite their enormous bulk,
14:42bears are surprisingly fast.
14:43However, bears are also quite happy
14:56to let someone else
14:57do all the work.
14:59And luckily for them,
15:01wolves are a willing workforce.
15:03Since wolves rarely eat
15:08all of their kill
15:09in one sitting,
15:10the carcass becomes
15:11an abandoned picnic
15:12just waiting to be exploited.
15:18Before wolves,
15:19only the hardest winters
15:20would bring a glut of carrion
15:21to the table.
15:23With wolves,
15:24the supply has not only increased,
15:26but is spread more evenly
15:28throughout the year.
15:29For bears,
15:31this is manna from heaven.
15:34And if they don't find
15:34an abandoned carcass,
15:36bears are more than capable
15:38of stealing one.
15:40Fear of wolves
15:42is most definitely not
15:43on this bear's agenda.
15:48Even a young bear
15:50will stand up to the pack.
15:55Despite strength in numbers,
15:57wolves know to respect bears.
15:59Their huge jaws
16:00and powerful claws
16:02mean business.
16:05When the stakes are even,
16:07bears and wolves
16:08will eat at the same table.
16:21Wolf kills have brought
16:22an unlikely bounty
16:24to Yellowstone.
16:25As a result,
16:26bear-cub survival
16:27has increased,
16:28and despite the obvious competition,
16:31the bear population
16:32is on the up.
16:34If bear predation
16:35had any impact
16:36on beaver populations,
16:38we'd not expect
16:39beaver numbers
16:40to increase
16:40alongside bears.
16:42But they have.
16:45So bears are not the key
16:47to the return of the beaver.
16:48So, wolf reintroductions
16:58and the success
16:59of beavers in Yellowstone
17:00are not connected
17:02with either the coyote
17:03or the bear.
17:05With two of Yellowstone's
17:07largest predators
17:08removed from our list
17:09of suspects,
17:10we must think again
17:11what other wolf relationships
17:13would lead ultimately
17:14to an increase
17:16in beaver numbers.
17:19Our attention
17:20must now turn
17:21to those animals
17:22whose lives
17:23are far more intertwined
17:24with those of wolves.
17:27Their prey.
17:31One of the animals
17:33on their menu
17:33is Yellowstone's
17:34most iconic grazer,
17:36the bison.
17:40Bison are built
17:41for the freezing
17:42Yellowstone winter.
17:46Bulls can weigh
17:47over a thousand kilos.
17:49They have an attitude
17:50to match
17:51and will happily
17:52stand their ground
17:53against a pack.
17:56These giants
17:57have been roaming
17:58the plains of North America
18:00since the last ice age.
18:03Their bulk
18:04allows them
18:05to stay warm
18:05from within.
18:07They can also
18:08slow their metabolism
18:09right down
18:10to save energy.
18:14Deep snow
18:14is no barrier
18:15to these enormous beasts.
18:20Their mighty neck muscles
18:21allow them
18:22to bulldoze
18:23the snow away
18:23to reach the grass beneath.
18:24It's estimated
18:35that 50 million bison
18:37once lived
18:37in North America
18:38before Europeans
18:40settled here.
18:42Over-harvesting
18:42caused total numbers
18:43across the continent
18:44to crash
18:45to less than
18:462,000
18:47in 1900.
18:48Now, thanks to
18:56careful management,
18:57their numbers
18:58across North America
18:59have swelled again
19:00to half a million animals.
19:03Today,
19:04almost 4,000
19:05live in Yellowstone itself.
19:08Only weak
19:09and old bison
19:10have anything
19:10to fear
19:11from wolves.
19:12but during
19:15the summer months
19:16it's the young
19:17that are most vulnerable.
19:19But for wolves
19:20it's still
19:21a risky business.
19:25Their strategy
19:26is to charge
19:27the herd
19:27and try to separate
19:28the calves
19:29from their mothers.
19:34But the bison
19:35are quick
19:36to react.
19:39A large bull
19:40joins the fray
19:41and working together
19:42they form
19:43an impenetrable wall.
19:45Any attempt
19:46at snatching a calf
19:47could bring
19:48fatal consequences
19:49for a wolf.
19:52The pack realise
19:54they've missed
19:55their chance.
19:57The threat
19:58of serious injury
19:59or death
20:00is always
20:01a good deterrent.
20:04They must be
20:05successful soon
20:06for they themselves
20:07have young to rear
20:08at this time of year.
20:11It's very rare
20:13for pups
20:14to be seen
20:14out in the open.
20:16Spending nearly
20:17all of their time
20:18in the den
20:18they only emerge
20:20when under the protection
20:20of the pack.
20:23A brief foray
20:24to the river
20:24gives them a chance
20:25to play
20:26and to view
20:27the kingdom
20:27they'll soon
20:28rule themselves.
20:29The alpha female
20:43will have around
20:43six pups.
20:45She must feed
20:45well so that they
20:46can stay strong.
20:49Weaned on her milk
20:50they're five weeks old
20:51before they can share
20:52in the spoils
20:53of the hunt.
20:54But for now
20:55they must not stay
20:56out in the open
20:56for too long.
20:57Here they're at risk
20:59from bears
20:59and coyotes
21:00so they're soon
21:01led back to the den.
21:04Breeding success
21:05in wolves
21:06is strongly linked
21:07to hunting success.
21:12If their kill rate
21:14declines
21:14then the wolf population
21:16soon follows.
21:20Bison provide
21:21plenty of meat
21:22but hunting them
21:23pushes wolves
21:24to their limits.
21:26Because of this
21:27bison are not
21:28the preferred prey
21:29of the wolf.
21:36With bison numbers
21:37changing little
21:38in response to wolves
21:39it's unlikely
21:40that they've had
21:41a major influence
21:42on the fortunes
21:43of beavers
21:43and river habitat
21:44within the park.
21:47So bison
21:48are not the link
21:49we're looking for.
21:52But there is
21:53one prey animal
21:54that's inextricably
21:55linked to the wolf.
21:59The elk.
22:06Numbering tens
22:08of thousands
22:08elk are the most
22:10numerous grazer
22:11in Yellowstone.
22:14Late summer
22:15is the time
22:16for the rut.
22:17The dominant male
22:21calls to advertise
22:22his status
22:23to females
22:24and to other males
22:26in the vicinity.
22:28His antlers
22:29are a sign
22:30of age
22:30and status.
22:36Made of bone
22:37antlers
22:37take a lot
22:38of energy
22:38to produce.
22:40They're shed
22:40and regrown
22:41every year
22:42so they're
22:44a clear
22:44and honest
22:45indication
22:45of the health
22:46of an individual.
22:48The dominant male
22:49is clearly
22:50in his prime.
22:52But there are
22:53challenges
22:53to the throne
22:54and he must
22:55prove his worth.
22:57The challenge
22:58starts with
22:59a ritualized display
23:00designed to
23:00size up
23:01and intimidate
23:02an opponent.
23:04If nobody
23:04backs down
23:05then contact
23:07is made.
23:07Fights may last
23:16many minutes.
23:17It's a dangerous
23:18time.
23:19A well-placed
23:20antler
23:20could mean
23:21certain death.
23:24This time
23:25the competition
23:26is seen off.
23:30And the victor
23:31can claim
23:32his prize.
23:33A large male
23:38may not eat
23:39for weeks
23:40during the rut.
23:41All he'll do
23:42is fight
23:42and if he's
23:44lucky
23:44he'll mate
23:45with all the
23:46females
23:46in the vicinity.
23:48Exhausted
23:49at the end
23:49of the rut
23:50he has very
23:51little time
23:51to feed
23:52and regain
23:52condition
23:53before thick
23:54snow
23:54covers the
23:55lands
23:55once again.
23:58And when
23:59the snows
23:59arrive
24:00the wolves
24:01come into
24:01their own.
24:03wolves hunt
24:08elk
24:08by chasing
24:09them across
24:09open country.
24:11This gives
24:12them time
24:12to select
24:13their quarry.
24:16By running
24:17the herd
24:18the pack
24:18can spot
24:19the weak
24:19and the slow.
24:24Many hunts
24:25end in failure
24:26but with teamwork
24:28and a bit of luck
24:29they can secure
24:30a meal.
24:31with wolves
24:33the elk
24:34population
24:34consists of
24:35only the
24:36healthiest
24:36animals.
24:38In this way
24:38wolves
24:39and elk
24:40are interdependent.
24:43However
24:43before the time
24:45of the wolf
24:45Yellowstone's
24:46burgeoning elk
24:47population
24:48grazed in
24:48open country
24:49without fear.
24:50and here
24:52lies the key
24:54to our puzzle.
24:56Without fear
24:57of predation
24:57by wolves
24:58the elk
24:59had free
25:00range
25:00and their
25:01grazing habits
25:02radically
25:02changed the
25:03landscape
25:03especially
25:05on the
25:05riverbanks
25:06where everything
25:07was grazed
25:08to the ground.
25:09Shoots of
25:10bankside trees
25:11were continually
25:11pruned
25:12and never
25:13gained a
25:13foothold.
25:15Without trees
25:15and shrubs
25:16strengthening the
25:17riverbanks
25:17erosion
25:18was rife.
25:20This was
25:21exacerbated
25:22again
25:22by the
25:23trampling
25:23of the
25:23herds.
25:25Without roots
25:26the water
25:27holding properties
25:28of the soil
25:28are diminished
25:29and summer
25:30flows decrease.
25:32This in turn
25:33encourages silt
25:34to build up
25:35in fish
25:36spawning beds.
25:38As a whole
25:38biodiversity
25:39decreased.
25:41Yellowstone
25:42was left
25:42with less
25:43habitat for birds
25:44and insects
25:44and less fish
25:46for otters
25:46and birds of prey.
25:48Then
25:50along came
25:51the wolf.
25:53The culture
25:54of fear
25:54instilled
25:55by the wolf
25:56returned the elk
25:57to their
25:58naturally flighty
25:59state.
26:01Elk no longer
26:02stay exposed
26:03in one place
26:04for too long.
26:05Instead
26:05the herds
26:07stay on the move.
26:14In their
26:14absence
26:15vegetation
26:16once chewed
26:17to its roots
26:17have had
26:18a chance
26:18to gain
26:19a foothold.
26:22Willows
26:23aspen
26:23and cottonwood
26:24trees
26:25started to
26:26recolonize
26:26riverbanks.
26:31This is prime
26:32habitat for much
26:33of Yellowstone's
26:34wildlife
26:34and absolutely
26:36essential for
26:37one in particular.
26:38the beaver
26:42beaver dams
26:45encourage the
26:45growth of
26:46aquatic plants.
26:48These in turn
26:49provide food
26:49and habitat
26:50for aquatic
26:51insects
26:51which themselves
26:53provide food
26:53for birds
26:54and fish.
26:57The enriched
26:59soil encourages
27:00further growth
27:00of trees
27:01creating more
27:02nesting and feeding
27:03sites
27:03for squirrels
27:05and birds.
27:10The resulting
27:10ponds act
27:11as reservoirs
27:12increasing water
27:13flow during
27:14the summer months.
27:17This provides
27:18a much better
27:19habitat for fish
27:20to breed in
27:20and fish
27:21provide an
27:22important resource
27:23for ospreys
27:24and otters.
27:27All this
27:28is the result
27:29of the most
27:29unlikely of
27:30connections.
27:32That's between
27:33Yellowstone's
27:34top predator
27:34and a shy
27:36industrious
27:37rodent.
27:39Yellowstone
27:40is once again
27:41a landscape
27:42shaped
27:42by fear
27:44of the wolf.
27:46By saving
27:47the wolf
27:47human intervention
27:49has had a far
27:50more beneficial
27:50impact than
27:51was ever
27:52thought possible.
27:54They control
27:55predator
27:55and prey alike
27:56and have
27:58unleashed a
27:58cascade of
27:59changes
28:00increasing
28:01biodiversity
28:01at all
28:02levels
28:02of the food
28:03chain.
28:06With wolves
28:08reinstated as
28:09apex predator
28:10Yellowstone
28:11is once again
28:12one of Earth's
28:13great micro
28:14worlds.
28:26Now good
28:27kind people
28:28wolves
28:29wolves
28:30also live
28:39in the
28:39Taurus
28:39mountains
28:40which is
28:41where
28:41Simon
28:41Reeve
28:42begins
28:42the second
28:42leg
28:43of his
28:43journey
28:43around
28:44Turkey
28:44in a
28:44moment.
28:45Then at nine
28:46Yunina Ramirez
28:47St. Alistair
28:48Souk
28:48explore the
28:49capital city
28:50of Azerbaijan
28:51the land
28:51of fire
28:52Baku.
28:53Taurus
28:54is
28:55a
28:55man
28:56who
28:56is
28:57a
28:57man
28:57who
28:58is
28:58a
28:58man
28:59who
28:59is
28:59a
29:00man
29:00who
29:00is
29:00a
29:01Gracias.
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