Nova (1974–…): Season 43, Episode 11 - Wild Ways - full transcript

From Yellowstone to the Yukon, to Southern Africa's elephant highways stretching across five nations, explore how newly established wildlife corridors may offer a glimmer of hope to some of our planet's most cherished-but endangered-species.

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-[growls] -[narrator] Lions...

-[trumpeting] -Elephants...

Bison...

-Wolves. -[all howl]

All over the world, their numbers are plunging.

But why aren't parks like Yellowstone

and wildlife preserves worldwide enough to save

these magnificent creatures?



As big as Yellowstone is,

it's not big enough on its own.

[narrator] These sanctuaries are fast becoming

islands of nature

in a sea of human development.

[Harvey Locke] And the first things to go

are the large mammals.

[narrator] With roads and highways

cutting them in half.

If you chop an ecosystem up, it's immediately in trouble.

[narrator] No longer can elephants migrate

as they have for thousands of years.

[elephants trumpet]

Gone are the vast expanses



lions need to roam and interbreed

to keep their prides healthy.

The females are mating with their cousins,

or their nephews,

even their fathers in some cases.

[narrator] Now, scientists are racing to save them.

[Mike Chase] We know with pinpoint precision

where the elephant is 24/7.

[narrator] Tracking their movements,

understanding their needs.

[Chase] It's a way of them communicating which areas

they need to move

across this vast landscape.

[narrator] Reconnecting parks

and preserves.

To allow our animals to move from one patch

of protected landscape into another.

[narrator] Making the most of

the wilderness that remains.

It's our last chance to protect the diversity

of life on Earth.

[narrator] "Wild Ways", right now on Nova.

[yelping]

[narrator] Tanzania, East Africa,

Serengeti National Park,

home of the greatest wildlife spectacle

left on Earth.

This is the great migration.

Two million wildebeest, zebra and gazelle

follow annual rains

along ancient pathways across Tanzania and Kenya.

Sheltered by national parks and game reserves

covering 12,000 square miles,

some species are still being lost.

[bellows]

Rhinoceros have been hunted out by poachers

for their horns.

Wildebeest and zebra are at risk

because their dry season water supply has been

diverted for human use.

A controversial road and rail project

threatens to sever the ancient

migration route...

And Serengeti is not alone.

All over the world, wild animals are at risk.

In the United States, Yellowstone is one of

our largest national parks.

With nearly 3,500 square miles,

it's bigger than some countries.

Millions come here each year to see its wildlife

and natural wonders.

But this park, like many around the world,

may not be doing its job.

[Stephen Woodley] We have set up

protected area systems

in all parts of the globe.

Most of them are too small

to protect the native biodiversity

that they're set up to protect.

[narrator] So what will it take

to save these animals,

especially when they leave protected areas

to forage for food and find mates?

This places them in danger

because even the best parks have become islands

of nature

surrounded by human development.

To find a solution, biologists are

following animals

along their ancient migration routes.

By understanding their patterns and needs,

scientists hope to come up with a new approach

to save wild species all over the world.

One key question is how much land

wild animals need to survive?

Back in the Serengeti, the African lion

stalks the great migration.

Lions survive by preying on the herds of wildebeest

and zebra.

Biologist Craig Packer has been studying

Serengeti lions for decades.

[Craig Packer] The Serengeti Lion Project

is one of the longest

continuous studies of any animal species on Earth.

We currently keep track of about 24 prides of lions.

That's about 300 individuals,

but since the study began in 1966,

after 50 years we have records of nearly

5,000 individuals.

So this is the female that walked off first.

-The old one. -Yeah. Yeah.

[Packer] She's got these three spots

on the right side.

But it's great having these pictures to go back.

[narrator] Packer knows every lion

in his study area,

-who they mate with, and how many cubs they raise.

-[camera clicks]

It's a unique natural history

going back many generations.

[Packer] Lions live in distinct groups

called prides,

which consist of a stable core of females

that live in the same general area

generation after generation.

[narrator] About a dozen lions live

communally in a pride,

females will even nurse each other's cubs.

Male lions come and go,

mating with females from different prides.

This promotes a healthy exchange of genes.

But if a park is too small and isolated,

this interbreeding can't take place

and the lions will be at risk.

Serengeti, about the size of Connecticut,

is large enough to support 70 lion prides.

Just to the southeast is Ngorongoro Crater,

which is a very different situation.

Ngorongoro features a protected area

in a volcanic crater.

The crater rim encloses a wildlife sanctuary,

but it's surrounded on all sides

by Maasai villages.

-[cows moo] -The Maasai survive

by herding cattle.

To defend their herds, or for prestige,

they will kill lions who would enter or leave

the volcano.

This means the Ngorongoro lions

are isolated

and that leads to inbreeding.

[Packer] So if you have a population

that's as small as the Ngorongoro Crater,

there's only about 30 adults,

and there the females are mating with males

who are their cousins, or their nephews,

or even their fathers in some cases,

and here's where you get a real risk

of inbreeding depression

and inbreeding depression can consist of

cubs that are smaller,

they might not live to their first birthday,

and in some cases they're much more

susceptible to disease.

[narrator] In addition, small populations are

more vulnerable to drought,

famine and over-hunting.

Studying lion populations all over Africa,

Packer has arrived at the minimum

number of lions

needed for a group to survive.

[Packer] Lions, like just about

any other mammalian species,

need to live in a fairly large population

in order to maintain its genetic health

and studies of these situations suggest

that they need to have

at least 1,000 breeding individuals

in the population

to maintain proper levels of genetic diversity.

[narrator] When an isolated population

is wiped out,

and there are no lions close by to resettle

the area,

that species is extirpated,

gone forever from that location.

Once over a million lions roamed and interbred,

from Great Britain to South Africa.

Today there are fewer than 25,000 left,

most living in a handful of

protected areas.

Only four preserves have the 1,000 lions necessary

for long-term survival.

Parks around the world face a similar problem

as human development encroaches.

If you chop an ecosystem up, it's immediately in trouble

and it will lose biodiversity guaranteed.

We know this as much as we know anything

in conservation biology.

[narrator] The loss of biodiversity

can be seen on every continent.

Large predators like lions

have declined by 99%.

Tigers have fewer than 3,000 survivors.

Grizzlies, mountain lions,

and wolves followed a similar drastic decline

in North America,

where bison plummeted from more than 30 million

to a few hundred.

These large mammals are the first to go

when a park is too small and isolated.

In North America, the grizzly bear

is a prime example.

Grizzlies used to inhabit most of Western

North America,

but as human populations grew,

bears were confined

to ever-shrinking pieces of land.

About 40 isolated bear populations

lasted into the 1920s.

Now, outside Alaska, there are only two viable

large groups in the US.

In and around Glacier and Yellowstone National Parks.

Yellowstone is the world's first national park,

founded in 1872.

At that time it was part of a wilderness

that stretched from Mexico to the Canadian Arctic.

But now it's surrounded by ranches, towns

and highways,

and that's a problem for species like

grizzly bears

that need room to roam.

Grizzly bears are true omnivores,

eating everything from berries to meat.

They dig for roots and tubers,

but will also consume fish, greens, or insects.

To make it through their winter hibernation,

they must put on a third of their body weight

in summer and fall.

In their search for food or mates,

it's inevitable that some bears will wander

out of Yellowstone.

This joint works good.

[narrator] Biologist Mike Proctor

wants to understand

the bears' habits

so they can be better protected.

[Proctor] We got a, uh... Canines are in

very good shape. The...

The incisors have medium wear.

They're still pretty good incisors,

so it's not an old bear

and then the third one, the molars are

medium worn,

so we're looking at a six to

eight-year-old male.

[narrator] Proctor darts and tranquilizes

grizzly bears

to monitor their health.

All right... All right I'm going to do

a physical exam,

just see how, any injuries or what shape he's in.

He's got a little wound there.

Why don't you write down, a wound,

it looks like a fight with another male.

Uh, right side of his cheek...

Puncture wound.

When we first get a bear immobilized,

we go in and make sure it's breathing correctly,

and do a round of vitals

we understand its heart rate,

oxygen concentration, its temperature.

We measure its, uh, weight, very important, its age.

We do quite a few other measurements of condition,

we look at parasites and ticks

and body condition in general.

We take blood. We take a DNA sample from their

hair, hand pulled.

Of course it's on a sleeping bear.

The heart rate's 60.

-Good thing I checked, it's fine.

-Oh, okay.

Perfect.

[narrator] Then he attaches a radio collar

that will track

the bear's movements using GPS.

[Proctor] After you put a radio collar

on a grizzly bear,

it collects GPS locations about every hour

for two years.

That collar follows the bear around the landscape

and goes everywhere it goes, every hour

and we find out every specific location

of that bear for a two-year period

and then you put that on 40, or 50, or 60 bears,

and you really start to understand the patterns

of how bears use landscapes, how they move

and how they use habitat and what is important

to them.

This is the, uh,

electronic drop-off time for

two years from now so this bear won't wear

the radio collar for the rest of his life.

They work pretty good. [grunts]

I'm gonna watch the head, pretty clear here.

His nose is twitching. Hey, we're done, we've got

an arm movement, let's go.

[grunts]

Pack up.

[narrator] The radio collar tells an amazingly

detailed life story

of grizzly bears...

Where they find food, make their dens

and choose mates.

After two years with his mother,

a male cub moves out of her territory.

But female cubs will settle nearby.

Males will travel widely, competing with other males

for mating rights to several females.

For example,

Proctor tracked one male,

as he moved several hundred miles

from Canada, across Idaho

and on into Washington

when his collar released.

The challenge is that only 25% of grizzlies

are breeding age females.

If a group becomes too small,

there won't be enough females

and that's the end of the line

for that population.

Proctor decided to use DNA evidence

to pinpoint where that's happening.

Bears have favorite trees they use for a good

back scratch.

Proctor realized he could use the fur

they leave behind

to test the bear's DNA.

Then he developed an even better method

to sample a lot more bears.

You know, I'm wrapping a

kitchen-sized barbwire corral,

which I'm going to fill

with very smelly bait to lure in a grizzly bear.

That grizzly bear is going to come in here

to smell that bait

and leave some hair on this wire.

And with that hair... He didn't even know

he's being sampled... We'll use it

for our, answer to conservationists' questions

using DNA fingerprints.

[narrator] DNA collected from the skin follicles

at the base of each hair, contains the genetic code

unique to each individual

and this can reveal whether different groups of bears

are related and whether they've been interbreeding.

[Proctor] We were looking for places

where grizzly bears were not interbreeding,

for some reason or other,

and we found many of those

places across the landscape.

They all correlated

with major highways and settled valleys.

[narrator] Where highways and human settlements

make it hard

for bears to move around and interbreed,

Proctor discovered that grizzlies

are becoming separated into genetically

different groups.

His DNA records identify 17 populations

from Yellowstone Park to the Arctic Circle.

In the Arctic, bears move freely

and interbreed.

Traveling south toward the US-Canada border,

isolation gets worse.

The 700 bears of Yellowstone are completely cut off,

almost as if they were living

on an island

and scientists now understand

why that is a threat to many species.

In fact, the first clues that parks may be in trouble

came from studying islands.

Starting with Charles Darwin's voyage

to the Galapagos

in the 1830s, a new field of biology developed,

known as island biogeography.

[David Quammen] Island biogeography,

it's a really important

field of study for conservation,

for the prevention of extinctions.

It's the study of where creatures live,

where they don't live and why.

Biogeography.

Island biogeography is that field of study

applied to islands, but, importantly,

also to island-like fragments

of habitat.

[narrator] Islands often are home

to unique species

like the Galapagos iguana

and the giant tortoise.

But islands have very limited resources.

The smaller the island, the fewer species

it can support.

To see how this principle applied to national parks,

which are like islands within the larger continent,

biologist Michael Soule and his students

launched a series of studies.

[keyboard clacking]

They wanted to know how well national parks

were doing

at protecting the species

that were there when the parks were created.

[Michael Soule] After doing this analysis

of what remained

in the national parks in the United States

was completely consistent with the principles

of island biogeography.

The bigger parks retain

almost all of their species,

but only the biggest parks still had grizzly bears,

and wolves and mountain lions.

The smaller the park, the fewer the predators

there were,

and the fewer the species there were overall.

[narrator] These studies became the foundation

for the new field

of conservation biology.

Soule discovered that a small park also has

another challenge for species survival...

The balance between males and females.

[Soule] Small size is bad for creatures genetically

and also demographically.

Because, for example, if there's only five

or six mountain lions

in a park and there's no...

They can't get in, they can't get out,

every few generations all those five or six

will be males

and that's the end of them because they can't

reproduce.

They're all males.

[narrator] No longer allowed in national parks,

hunting has had a huge impact

on animal populations.

[howling]

Considered pests, wolves were completely hunted

out of Yellowstone in the 1920s.

Today, Doug Smith directs the Yellowstone

Wolf Project,

created to bring wolves back into the park.

Smith and the Yellowstone Wolf Project

collar and track the newly returned

wolf packs.

Reintroduced in 1995,

wolves now occupy every part of the park.

They were brought back into Yellowstone

because biologists realized

that without them the entire ecosystem

-was starting to unravel. -[camera clicks]

In 75 years without wolves, Yellowstone's elk population

had surged and was destroying

the important river bottom ecosystems.

Willow plains like this were rare and eaten down.

When I first came to Yellowstone in 1994,

stands like this were down to my knee level,

and every stem was clipped off by an elk.

I mean every stem.

[narrator] Without the willows,

many birds disappeared.

Without willows shading the streams,

water temperatures rose and fish populations

declined.

Beavers declined as well and without

their constant maintenance

of wetlands, erosion grew worse.

But when wolves were reintroduced in 1995

and started hunting elk,

the river bottom willows recovered.

[Smith] This growth in structure

has produced bird habitat.

We're getting birds like willow flycatchers

and Wilson warblers

that we have not had before.

We've had an increase in beavers.

This very willow plain here, I survey it, has,

depending upon the year, four to six beaver colonies

right back through this.

They increased 12-fold after this

willow resurgence.

[wolves howling]

[narrator] Biologists believe the

ecosystem is recovering,

but the question is whether Yellowstone's wolves

can survive

if they can't reach other wolf groups.

[Smith] Wolves are going to have to be connected

to other wolves.

Through time that has been shown to be

the saving grace for a population of animals.

We need that connectivity, we can't just do it

with this island called the Greater

Yellowstone Ecosystem.

[narrator] If animals can't come and go,

the parks we are counting on

to save wildlife are in trouble.

But biologists have a solution.

[Soule] Conservation biologists

have known how to end

the extinction crisis,

to protect thousands of species

in the United States and other parts

of the world,

by simply,

uh, restoring the connections

between the wild places that still persist.

[narrator] It's known as connectivity

conservation.

Linking the last places where wild animals survive

makes the most out of the core habitats that remain.

But which places outside of parks

are the most important to protect?

To find out, scientists like Mike Proctor

follow the animals.

[Proctor] One of our first bears we caught

crossed the highway

about 12 times in one summer exactly in the same spot,

and that taught us there was something

very important happening at that particular site.

The next year when I came back to work,

there was a "for sale" sign right at the spot

where this bear crossed the highway 12 times

and I just went, okay, a light bulb

went off in my head.

Even though I don't have perfect data yet,

I need to sort of act.

This is, uh...

[narrator] Mike Proctor worked with

conservationist Harvey Locke

to find a way to protect the bears' crossing place.

[Locke] Research by Dr. Michael Proctor

with the Trans-border Grizzly Bear Project

showed that this rather sad little parcel of land

over my shoulder

turned out to be the key connector

for the mother lode of grizzly bears

located in the wild Purcell Mountains

in Southern Canada, across this highway,

south into the States

to the recovering population of grizzly bears

in the Cabinet-Yaak area of northern Montana.

[narrator] Protecting this landscape connection

has enabled bears

to move south from Canada's Purcell Mountains

and connect with grizzly populations

in Montana and Idaho,

which are too small to survive over time.

This linkage, called the

Kid Creek Corridor,

is one piece of a much larger vision.

[Locke] When it became clear through conservation biology

that these wonderful national parks

like Yellowstone and Banff, as great as they were,

weren't sufficient unto themselves,

that they needed to be connected

to each other,

we came up with this idea called

the Yellowstone to Yukon Conservation Initiative...

The idea of making a great corridor

up the Rocky Mountains from Yellowstone

all the way into Northern Canada

near the Arctic Circle.

[narrator] Yellowstone to Yukon

is an ambitious plan

to link national parks.

These core areas are safe havens

where animals can find food,

breed and live

without being threatened.

Connecting them would recreate

the large landscape that existed

before humans came.

[Locke] Now we know that

as big as Yellowstone is,

it's not big enough on its own.

Islands in a landscape become islands

of extinction,

and the first things to go are the large mammals.

The large mammals, the ones that are at

the greatest risk

-of disappearing in the 21st century,

-[trumpets]

the big things like elephants,

and bison and grizzly bears,

and lions require us to practice conservation

at an enormous scale.

[narrator] The plan is to create

a 2,000-mile corridor

linking Yellowstone to the wilderness areas

of Central Idaho.

This would connect to Glacier National Park

and to Waterton Park across the US-Canada border

and on to Banff, Canada's premier national park.

Farther north, protected areas

become bigger and wilder,

all the way to the Peel Watershed

in the Yukon Territory.

The point is not to take over private land

along this corridor, but to work with landowners

and managers of public lands like national forests,

so that wildlife can safely move through.

Proctor's bear DNA map has identified the private lands

most critical to landscape connections.

One of these, in British Columbia,

is known as the Duck Lake Corridor.

Typically in our part of the world,

the mountains are in public hands,

and the valley bottoms are in private hands.

This Duck Lake Corridor is a classic example.

[narrator] Grizzly bears live in the mountains,

but they need to cross private lands in the valley

to find mates and forage for food.

Conservationists have purchased some of this land,

but also work with landowners

to find ways to protect animals

passing through.

They encourage farmers to fence in orchards,

since bears will go after berries and other fruit.

They also recommend bear-proof containers

for securing garbage.

Specially designed bins

can help keep bears away

from human settlements and farms,

where they may wind up getting shot.

Clearing the way for bears

can help protect other species, too.

For example,

biologists learned that the Duck Lake area

is critical for the seasonal migration

of northern leopard frogs.

We know that this mosaic

of habitats from farmers field,

to wildlife sanctuary, to pieces of public land,

is the critical corridor

for grizzly bears.

And we also know that if we can protect

the movements of grizzly bears

in these Rocky Mountains

across the landscape,

that we're going to catch something

like the needs of 85% of the other species in the system.

[narrator] Grizzlies are an indicator species,

a way to gauge the health of not just one species,

but an entire ecosystem.

Another major barrier to wildlife

is the four-lane highway.

With several lanes of traffic

and speeding cars and trucks,

these roads can be death traps.

Many animals are not as lucky as this cub.

Millions are killed every year.

Two major highways cut across

Yellowstone to Yukon...

Interstate 90 in Montana and Idaho,

and the Trans-Canada Highway which runs right

through Banff National Park.

[Woodley] Banff is Canada's

iconic national park,

and it's split by major transportation corridors.

And as the traffic volume went up in the Trans-Canada,

it fractured the park into two sections.

And large numbers of elk, and grizzly bears,

and black bears, and coyotes

were getting killed every year,

and it was very dangerous for people.

[narrator] Woodley and other scientists

at Parks Canada helped design

a road that would protect both humans and animals.

Forty-four crossing structures

now allow wildlife to move safely

through Banff National Park.

[Woodley] There's two basic kinds

of crossing structures,

there's the underpasses which are dark tunnels,

and then there's the overpasses.

When you're on top of them,

even though you have a four-lane highway

running underneath you,

it seems like you're in the forest,

trees growing on them.

And it seems like

certain kinds of animals like grizzly bears

and wolves like to use

those kinds of crossing structures.

[narrator] Motion-activated cameras

have documented more than

200,000 wildlife crossings,

and the number of animal deaths

has been reduced.

South of the US-Canada border

is the flathead Indian reservation,

a key crossing point for animals moving between

Glacier National Park

and the Church Wilderness area in Idaho.

But Route 93 runs right through the reservation.

When it came time to repair the highway,

tribal elders insisted on a design

that would be safe for animals and people as well.

Today, 43 crossing structures complete

one of the most

wildlife friendly road projects in the world.

Whisper Camel Means is a wildlife biologist

for the Salish and Kootenai Tribes.

She maintains a network of motion-sensor cameras

to document animals using the crossing points.

[Camel Means] The crossing structures

are being used.

We're pretty impressed about the number of animals

that are using them.

There's this whole new concept of road ecology

where people are actually thinking about

how roads affect the ground

and affect natural resources,

and affect all of us.

[narrator] Unlike the Trans-Canada

Highway

in Banff National Park,

Route 93 runs through ranches and towns.

Local residents had to be convinced

that the crossing structures were worth the expense.

[Camel Means] The cost of building

these crossing structures,

and putting this type of mitigation into

a road project

is less than the cost of

a bunch of people hitting animals,

a bunch of people getting into wrecks,

people losing their lives.

They're not that expensive

when you look at the big picture.

[narrator] This project allows animals

to safely move to and from

the large wilderness areas of Central Idaho.

But between there and Yellowstone in Wyoming,

the area is filled with cattle and sheep ranches.

The Centennial Valley is a piece of the old west,

featuring large ranches

that stretch as far as the eye can see.

Jim Roscoe is a biologist who works with ranchers

to help wildlife safely pass through their land.

[Jim Roscoe] If there's any one thing

that might have

some pretty substantial

impact for animals being able to move,

yet isn't a huge change in somebody's management

or extremely costly, it might be dealing with

wildlife-unfriendly fences.

[narrator] Outdated fencing poses

real obstacles

to animal movement.

It's a woven wire that has all these little squares.

Uh, these things become buried in the ground

and are a significant barrier to anything that's

trying to move through here.

The worst of it is, is that

whether it's a young deer,

young antelope, young elk, young moose,

they have a really difficult time dealing with this.

[narrator] Even fully grown antelope

struggle with these

old sheep fences.

Built for speed, they can't jump very high.

They need a fence design they can duck under.

[Roscoe] These are the kind of fences

that we're looking at

across the landscape of trying to modify,

or replace, or remove where we can,

uh, because there's other

fence designs out there that can be as effective now

and removes this total barrier to wildlife.

The other thing you can do, certainly, is

it's plain and simple,

is that if you've got gates in the fence,

leave the gates open when the livestock

aren't in the pasture.

[narrator] But the most contentious

issue around Yellowstone

is what to do about wolves,

since they were reintroduced here

in the 1990s.

The problem occurs when

wolves wander beyond park boundaries.

[mooing]

Martin Davis is a rancher in Paradise Valley,

just north of Yellowstone Park.

[Martin Davis] I wish wolves weren't here

that I had to worry about.

It's just one more thing we have to worry about.

We have to go to the mountains

and check on those cows

uh, every other day now,

where back in the day before wolves,

we were able to check on them just once a week or so.

When the wolves are bothering the cows a lot,

then we've found our weaning weights are down,

pregnancy rates down,

so it's been quite an adjustment over the last

15 years or so.

[narrator] Some ranchers take

a harder line on wolves.

State laws permit them to shoot wolves on sight.

Hunters are also angry at the spread of wolves,

which they say impacts the elk hunt.

States surrounding Yellowstone have

opened wolf hunting seasons.

Many of the collared wolves scientists track

have been killed when they

leave the protection of the park.

Wild bison are also targeted,

as some ranchers worry

that they might spread disease to cattle.

It's these kinds of issues that have to be resolved

before national parks can be fully connected.

[Quammen] The vision of connecting

Yellowstone to the Yukon,

it's hugely ambitious, it's not impossible.

It'll take a lot of

really patient, pragmatic,

cooperative work on the ground

with all these different people

who live and make their livings

on that landscape between these wild places.

[narrator] In the far north where there

are fewer people and many animals,

some core wildlife areas are gaining ground.

In Canada's northwest territory,

an area the size of Switzerland

has been protected.

Virginia Falls on the Nahanni River

is higher than Niagara.

It is the centerpiece of the newly expanded

Nahanni National Park Reserve.

[Locke] The Nahanni National Park

was all about creating a big northern anchor for

the Yellowstone to Yukon corridor.

This park is three-and-a-half times

bigger than Yellowstone.

That's why we worked so hard to expand

Nahanni National Park Reserve by six times.

It operates at the scale

of an entire wilderness watershed.

It protects a population of about 500 grizzly bears,

ranges of two or three caribou herds,

a big population of Dall sheep.

It's one of the world's biggest national parks,

and one of its most beautiful places.

[narrator] Although far from complete,

Yellowstone to Yukon has become a model

for similar projects worldwide.

Eight countries in Central America

have made initial efforts to protect

the Mesoamerican Biological Corridor,

known as the Path of the Panther.

In Australia, conservationists are working

to connect protected areas

for 2,000 miles along the east coast.

The goal is to preserve the continent's iconic wildlife,

including koalas, cassowaries, and platypus.

In Asia, scientists hope to link parks across

northern India, Bhutan, and Nepal.

This area runs from the world's highest peak

to lowland jungles and will help protect species

like Bengal tigers and snow leopards.

[trumpeting]

Perhaps the most ambitious

project outside North America

is in southern Africa,

where five countries are cooperating

to create the largest network of protected areas

on the continent.

Angola, Botswana, Zambia, Zimbabwe, and Namibia

are working together to reassemble a landscape

of over 150,000 square miles.

It's known as the Kavango Zambezi Transfrontier

Conservation Area

or the KAZA TFCA.

The network will link

36 parks across five nations.

These lands hold a healthy number of great cats...

Lion, cheetah, and leopard, as well as hippo, giraffe,

and a host of antelope species.

At the heart of this region is Botswana,

where Chobe National Park

harbors the only large elephant population

left in the world, numbering about 200,000.

Here, biologist Mike Chase leads a group called

Elephants Without Borders.

[Mike Chase] One of the tools that

the decision makers have had

in delineating the boundaries of KAZA

is to use the ranges of elephants...

How far these elephants are moving

within each of the particular countries,

as well as identifying those critical linkages,

those corridors,

which areas connect the protected areas.

[narrator] To follow the elephants,

Chase has to use

jumbo-size satellite collars.

The process of darting always starts

by us identifying a focal area,

a region where we want to collar elephants in.

And so the particular area that we've identified

is a series of artificial water holes

that elephants tend to concentrate in large numbers

during the peak dry season.

We're looking to collar an elephant between the age

of 20 and 25.

It's these young bulls that have this propensity

to really move vast distances to explore

and reconnoiter new areas.

[narrator] Tranquilizing a three-ton elephant

requires a powerful drug.

The veterinarian handles these darts with care.

A single drop would kill a human.

The darts are shot from a rifle,

and although these bull elephants won't be harmed,

approaching them with a pointed gun can be risky.

It's a tense 15 minutes

before the elephant falls asleep.

The team hopes he won't run too far,

or enter a deep thicket.

Sometimes he just kneels down

and they have to give the sleeping animal a push.

[man] Okay, watch for that foot.

[narrator] Then it's time

to attach the collar.

The satellite unit is at

the middle of the base of the neck.

Okay.

Typically the collars are on an elephant

for a period of two years,

and we get a GPS location

every hour during that period.

We know with pinpoint precision

where the elephant is 24/7.

Okay, we're almost there, Larry,

just tightening these nuts.

[narrator] Since they can't carry

a scale big enough for an elephant,

they take body measurements to estimate weight.

Three meters and four centimeters.

[narrator] This big fellow checks in

at about 5,000 pounds.

Follow his leg in the center.

[narrator] Elephants' ears

are their cooling system.

It's the best place to find a blood vessel

to administer the antidote.

[woman] Antidote's in, guys.

[narrator] It takes about five minutes

for the elephant to wake up.

Meanwhile, the team retreats to a safe distance.

[Chase] Collaring elephants is

really critical to the work

that Elephants Without Borders is doing.

So the collars provide us with vital information

on not only the movements of elephants,

but that the habitats that

these elephants need to survive.

And with this information, we're better able

to conserve elephants.

It's a direct link that I have with these elephants.

It's a way of them communicating with me

which areas they need

to move across this vast landscape.

[narrator] Elephants cover enormous

territories in their search

for food and water.

An average elephant eats about

300 pounds of vegetation a day,

and drinks about 50 gallons of water.

Female, baby, and juvenile elephants

live in breeding herds,

30 to 60 individuals led by a matriarch.

Using her encyclopedic memory,

this grandmother guides her extended family

to seasonal food and water supplies

across hundreds of square miles.

Increasingly, she must also keep track of which areas

are safe from human conflict and poaching.

Bulls live alone or in bachelor groups

until they enter musk,

and start searching for a mate.

[Chase] The information from

collaring nearly

130 elephants throughout

the Kavango Zambezi TFCA,

has really provided new evidence

on the spatial ecology of elephants.

[narrator] Spatial ecology, as it's

called, maps the lands

animals need to live in

and move through to meet their needs.

Chase's collars have helped pinpoint where cattle fences

and human settlements are

cutting off elephants' migration routes.

Since some fences were taken down,

elephants have been tracked traveling from Botswana,

across Namibia to southeastern Angola.

To get the big picture of elephant numbers

and distribution, Chase has to get up into the air.

To make accurate counts, he installs a pair of rods

on each side of the plane to calculate how much ground

they are covering.

Observers record every large mammal they see

between the rods, and take photographs

to confirm their numbers.

[woman on radio] I've got a breeding herd,

eight adult elephants

and five juveniles.

[Chase] In addition to counting

elephants, we will count

sable, roan, eland, giraffe, kudu, hippo.

So when we say we're counting elephants,

we're really recording and observing

a host of other wildlife species.

[narrator] But here, too, human settlements are

an important factor.

[bells clanging]

While much of Africa is sparsely settled,

its human population has doubled in just 40 years.

As more people come to live around parks,

there's less room for animals,

so conflict is inevitable.

[mooing]

[speaking foreign language]

[Chase] He says there are very many elephants.

There are lots and lots of elephants.

[Thomas speaking foreign language]

During the rainy season,

when they've planted their crops,

elephants come in and crop raid,

and it's a bad time of year with conflict.

If the elephant's in their cropland,

they shoot it, and they report it to wildlife.

Wildlife will come, remove the tusks,

and the meat is shared between the villagers.

To avoid human-elephant conflict

and tragic incidences such as this,

you just need to provide elephants with safe access

to the traditional migratory routes which they've been

using for thousands of years.

[narrator] Maintaining these ancient

corridors is critical

for the survival of animals

and the safety of humans.

People and wildlife are often killed

in these conflicts.

[gunshots]

Wildlife patrols try to steer the elephants away

from farmers' crops by shooting firecrackers

called bear bangers.

To limit conflict, the KAZA conservation effort

is developing incentives

so communities can see a benefit

from wildlife.

[Simon Munthali] To ensure and facilitate

ease of movement of wildlife

across the KAZA landscape,

it is important

that we provide incentives

for local communities in particular,

who should now look at wildlife

as some form of an economic asset to themselves.

And once they start benefitting from wildlife,

they are going to accept

wildlife moving across their land,

as well as contribute to protecting it.

[narrator] To encourage local support,

Botswana has developed an ecotourism industry,

which provides jobs and a cash economy.

Other African countries would like to develop

similar programs.

But it depends on maintaining

healthy wildlife populations

and safe corridors to link protected areas.

But just as elephants have begun to use the corridors,

they have encountered a deadly threat.

The ivory trade has spread to southern Africa

and with it, an epidemic of poaching.

In one park in southern Zambia,

Mike Chase counted 281 elephant carcasses,

and only 133 live elephants.

[Munthali] If poaching exists,

wildlife will not move.

Communities can provide land.

Governments can provide men and resources,

but if we don't deal with poaching,

wildlife will not move.

That is the biggest challenge, is poaching.

[narrator] Angola has been

a tragic case.

It used to have the largest elephant

population in Africa,

200,000 individuals.

But more than half, at least 100,000 elephants,

were killed to feed troops and buy arms

during the long Civil War of the 1990s.

But after the war ended,

the elephants began to return.

[Chase] Those elephants

that weren't killed,

we suspect fled

to the safety and security of Botswana.

And when I first started this study in 2001,

we were able to document

the repopulation of elephants,

elephants moving back into

these woodlands of southeast Angola,

which coincided with the end of the Civil War.

[narrator] The return of elephants

to Angola provides

important evidence

that if international efforts to eliminate

the ivory trade succeed,

elephants will use safe corridors to repopulate

their historic lands.

[Chase] The KAZA TFCA is one of

the last great hopes

for elephant conservation in Africa.

You know, if we can't get it right

in this corner of Africa,

the prospect of elephant conservation elsewhere

in Africa seems bleak.

The repopulation of southeast Angola,

you know, from estimating 100 elephants

to 8,000 elephants,

is arguably one of the greatest conservation

success stories in the last 50 years.

And it's in that spirit and that optimism

that I think that KAZA has the ability to be a refuge

and provide a future for elephants in Africa.

[narrator] Elephants and other

wild species,

lions, grizzly bears, and wolves,

all require room to roam.

Our national parks are essential to their survival,

but conservation biology tells us

they are not enough.

The question is, are there ways to connect these parks

so that the wildlife that

makes them so special can be saved?

[Quammen] To recreate connectivity,

to allow our animals to move

from one patch of protected landscape into another,

we have to make some adjustments.

Some of those adjustments involve adjustments

to the landscape, like overpasses,

and some of those adjustments

are psychological,

cultural, social.

We need to find ways in which people can live

with wildlife and wildlife can live

with people.

[Packer] If we as a species, we as

people in Asia, Europe,

North America, agree that we want these species

to continue into the future along with us,

then we have to take that responsibility,

and we have to find real mechanisms

that will provide the resources

in order to assure

their conservation into the future.

[Soule] This era that we're in now

could be a wonderful opportunity

or a tremendous failure for humanity.

It's our last chance to protect the diversity