[ADAM COLE] This is an island fox.
It might look like a docile pup, but it's full grown and completely wild.
It’s just not that afraid of humans – it’ll even sit in the lap of a biologist
while she does a quick checkup.
Though it only weighs about 4 pounds it's like the lion of its range,
the top land predator around
hunting mice, crickets and beetles.
You can only see this unique species
if you visit this little island chain.
The Channel Islands off the coast of Southern California,
and it's incredible that you can
still see these foxes at all.
See, back in the early ’90s, almost all of the foxes just disappeared.
And no one knew why.
They were classified "endangered," and it seemed like this would be just
another gloomy extinction story.
Just one more entry in the long list of species disappearing all over the world.
But this time ... that's not what happened.
Stick around and I'll show you what it took for a group of fox defenders
to bring this species back from the brink.
The first thing the fox defenders had to figure out: What was killing all the foxes?
The answer they pieced together was complicated
— a tangled story of eagles, pigs, fish
and a war that started decades ago on the other side of the world.
[ANNOUNCER] Because we're fighting a total war,
our forces must be marshaled against every enemy
unseen as well as seen.
[COLE] It's 1943, and thousands of soldiers and civilians fall to insect-borne diseases
like malaria and typhus, until ...
the allies develop a powerful pesticide:
DDT.
It helps win the war and eradicate malaria in Europe,
but indirectly, it's the start of trouble for the foxes.
See, the largest DDT producer in the U.S.is in LA,
and it spills 17,000 tons of chemicals into the waters
around the Channel Islands.
The foxes have been safe here for thousands of years.
No serious predators.
The bald eagles who rule these skies don't care for foxes — they prefer fish.
But when DDT travels up the food chain into these fish,
it makes the shells of the bald eagles' eggs
way too thin.
They're crushed by their own parents.
By the ’90s, that LA facility is shut down and cleanup efforts begin,
but the damage is done.
There are no more bald eagles,
and with the skies unguarded,
a slightly smaller raptor moves in.
The golden eagle.
And the thing is, unlike the bald eagle, it doesn't like fish.
It prefers little land mammals.
And that's not the only problem —
the foxes also share their islands with feral pigs
that were introduced by farmers in the 1850s.
The pigs destroy fox habitat, and their tasty piglets are just another little mammal
that keeps golden eagles coming back to the islands.
It's a perfect storm;
an ecosystem out of whack.
The foxes are almost gone ...
[LOTUS VERMEER] And if we don't do something, you're never going to see them again.
[Cole] Lotus Vermeer was working for the Nature Conservancy,
a nonprofit that owns 3/4 of Santa Cruz Island.
Vermeer and a team of conservationists, veterinarians and volunteers
tried to put this broken ecosystem back together.
[VERMEER] "There was more than one occasion
where people would walk into my office and I'd be lying on the floor —
just: ‘Oh my goodness, how are we going to do this?’"
[Cole] They needed to deal with the pigs and the golden eagles
and bring back the bald eagles — all before the last foxes were killed.
The pigs were an invasive species, and the team realized they would have to go.
[VERMEER] I am a huge animal lover and
the thought of having to kill an animal is something that I took very seriously.
It was very clear what had to be done.
[COLE] Hunters from New Zealand combed Santa Cruz Island
— an area four times the size of Manhattan —
with dogs and a helicopter — every single day
for a solid 18 months.
[VERMEER] "And at the end we were able to remove 5,036 pigs."
[COLE] Next up: relocate the golden eagles.
These are clever birds, and they quickly learned to avoid traditional ground traps.
So the fox defenders tried all kinds of things.
Luring them with robotic stuffed foxes.
Rappelling down to their nests.
[VERMEER] My personal favorite was the injecto-egg.
COLE]It had a hidden remote-controlled dart that was supposed to tranq the parent eagle
but the egg would roll, and the dart would miss.
[VERMEER] So that one never worked.
[Cole] In the end, they had to chase them to exhaustion in a helicopter
then, when they got close to the ground
fire a net over them.
It took seven years to nab every eagle
and relocate them to the other side of the Sierras.
To make sure that the goldens didn't come back,
they needed bald eagles patrolling the skies again.
So, a California nonprofit called the Institute for Wildlife Studies
hatched and raised dozens of bald eagle chicks.
When those birds got a little older, they were released on the islands.
After a few years, a couple paired up and built a nest.
Vermeer and the rest of the team watched via webcam.
[VERMEER] Both parents are there looking, walking
anxiously around the nest and all of sudden "boop."
[COLE] This was the first bald eagle to hatch naturally on the Channel Islands in over 50 years.
[VERMEER] What a beautiful and hopeful event this was.
[COLE] While all this was happening, the foxes were still teetering on the edge of extinction.
Tim Coonan knew something drastic had to be done.
[TIM COONAN] There were so few of them left that we knew we had to start a breeding program
to build up their populations.
[COLE] That meant they had to build these secure pens and scour the islands to collect
the few dozen surviving foxes they could find.
[COONAN] Removing a wildlife species from its environment is one of the most
onerous things you could do, and as a wildlife biologist, you never want to have to do that.
[COLE] The foxes hadn't been bred in captivity before — scientists didn't know much about
their reproduction, their diseases, even their diet.
[COONAN] And the stakes were even higher because island foxes have less genetic diversity
than many other species.
[COLE] They're all really alike genetically — like cousins.
So the biologists paired up foxes that were least similar, to try and preserve what genetic diversity they could.
And the foxes didn't waste time.
Before long, pups were born and foxes started being released back into the wild.
By 2016, they had returned to their historic abundance
and were taken off the endangered species list.
It was the fastest recovery in United States history.
Today, the fox defenders aren't resting easy.
[COONAN] We'll watch them like hawks, so to speak.
[COLE] I tagged along on a fox-trapping run.
Biologists inoculate the foxes against rabies and canine distemper
and keep close tabs on their numbers so they're not surprised by future threats.
This species' ecosystem fell apart because of human activity,
and it took decades of painstaking effort by hundreds of people to put it back together again.
[VERMEER] It was all worth it.
Even though they're everywhere now, it’s still really special to be able to see them.
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