[ GEIGER COUNTER CLICKING ] Narrator: DEEP IN THE FORMER SOVIET UNION, THERE IS AN EXCLUSION ZONE -- CONTAMINATED LAND THAT HAS EVOLVED WITHOUT HUMANS FOR 25 YEARS... CHERNOBYL.

WHEN DISASTER STRUCK THE NUCLEAR POWER PLANT IN 1986, ALMOST HALF A MILLION PEOPLE WERE DISPLACED.

THEN, IN THE ABSENCE OF HUMAN LIFE, WILDLIFE FILLED THE VOID.

NOW FORESTS, MARSHES AND FIELDS TEEM WITH ACTIVITY.

BUT THIS IS LAND THAT HAS LONG BEEN LOCKED AWAY, THE HABITAT IS UNCHARTED, AND THE WILDLIFE UNTESTED.

RUMORS SPREAD ABOUT HUNDREDS OF WOLVES THAT SEEK HAVEN HERE.

NOW SCIENTISTS WANT TO TRADE FICTION FOR FACT.

THEY'LL TRY TO DETERMINE IF MANKIND'S DISASTER GAVE NATURE A SECOND CHANCE... OR, IS THIS FOREVER-TAINTED TERRITORY THAT COULD POISON EVERYTHING THAT CROSSES ITS PATH?

[ THEME MUSIC PLAYING ] [ GLASS SHATTERS ] Narrator: APRIL 26, 1986 -- MELTDOWN AT BLOCK 4 OF THE CHERNOBYL NUCLEAR POWER PLANT IN THE SOUTHWEST OF THE SOVIET UNION.

THE EQUIVALENT RADIATION OF 400 HIROSHIMA BOMBS IS RELEASED.

400,000 PEOPLE ARE FORCED FROM THEIR HOMES FOREVER.

CLOUDS OF RADIOACTIVE DUST DRIFT ACROSS EUROPE -- CONTAMINATION ON A CONTINENTAL SCALE.

HARDEST HIT IS AN AREA OF ALMOST 1,100 SQUARE MILES AROUND THE REACTOR.

THIS LAND IS DECLARED UNFIT FOR HUMAN HABITATION -- AN EXCLUSION ZONE THAT CAN ONLY BE ENTERED BY SPECIAL PERMISSION THROUGH ONOF SEVERAL CHECKPOINTS.

VISITORS, INCLUDING SCIENTISTS AND CAMERA CREWS, ARE GIVEN DAILY AND OVERALL TIME LIMITS, AND MUST BE ACCOMPANIED BY OFFICIAL GUIDES.

HERE, THE WELL-KEPT COUNTRYSIDE SUDDENLY ENDS.

WHEN THE SOVIET UNION BROKE UP, THE ZONE WAS SPLIT IN TWO, BETWEEN THE NEW NATIONS OF BELARUS AND UKRAINE.

THE NEW BORDER IS STRICTLY MAINTAINED, EVEN WITHIN THE ZONE.

BEYOND THE CHECKPOINTS IT'S A DIFFERENT WORLD... A WORLD WITHOUT HUMANS... THE ZONE -- CONTAMINATED, RADIOACTIVE, ABANDONED.

IS THIS A GLIMPSE INTO THE FATE OF THE WORLD AFTER DOOMSDAY?

WHEN HUMANS FLED, WILDLIFE STAYED BEHIND.

HOW ARE THE SURVIVORS AND THE NEWCOMERS COPING WITH THE INVISIBLE BLIGHT ON THIS LAND?

RESIDENTS AND MIGRANTS ALIKE KNOW NOTHING OF THE LURKING DANGER.

THE FALLOUT FROM THE NUCLEAR ACCIDENT HAS SEEPED INTO THE SOIL.

FROM THE SOIL, RADIOACTIVE PARTICLES ARE ABSORBED BY PLANTS.

THEY'VE ACCUMULATED IN THE TREES, AND HAVE BECOME CONCENTRATED IN THE ORGANS AND BONES OF ANIMALS.

YET, STRANGELY, THE ILL-FATED REACTOR HAS NOT CREATED A DESERT, BUT A LUSH WILDERNESS.

IT'S EVEN INVITED IN THE VERY SYMBOL OF THE WILD -- THE GRAY WOLF.

[ WOLVES HOWLING ] [ WIND WHISTLING ] FOR YEARS, RUMORS HAVE BEEN ESCALATING ABOUT THE NUMBER OF WOLVES IN THE ZONE.

SOME SAY 300 OR MORE.

GERMAN SCIENTISTS BARBARA AND CHRISTOPH PROMBERGER ARE CARNIVORE EXPERTS.

THEY'VE STUDIED WOLVES AROUND THE WORLD, BUT NEVER IN SUCH STRANGE CIRCUMSTANCES.

THE PROMBERGERS ARE HERE TO START A LONG-TERM STUDY TO BE CONTINUED BY LOCAL SCIENTISTS.

THEY'RE HOPING TO ANSWER SOME FUNDAMENTAL QUESTIONS -- HOW MANY WOLVES ACTUALLY LIVE IN THE ZONE?

ARE THEY INDIGENOUS, OR RECENT IMMIGRANTS?

AND, IS THE ZONE'S WOLF POPULATION ANY DIFFERENT FROM POPULATIONS IN CLEAN AREAS?

THESE MOOSE BONES HAVE BEEN CRUSHED BY WOLVES.

IT'S A CHANCE TO FIND OUT WHETHER THE WOLVES' DIET IS CONTAMINATED.

[ MACHINE BEEPING, PROMBERGERS SPEAKING GERMAN ] THE RADIATION IS 50 TIMES NORMAL.

THERE ARE PLENTY OF FRESH WOLF TRACKS HERE ALONG THE BANK OF THE PRIPYAT RIVER.

A WOLF HAS BEEN MARKING THIS YOUNG PINE, MAKING IT THE PERFECT PLACE FOR A TRAP.

THE PROTECTIVE GEAR IS TO PREVENT CONTACT WITH CONTAMINATED SOIL, AND TO AVOID TRACES OF HUMAN SCENT.

BARBARA AND CHRISTOPH HOPE TO RADIO-COLLAR SEVERAL WOLVES TO STUDY THEIR MOVEMENTS.

THEY BAIT THE TRAP WITH WOLF URINE.

THAT AFTERNOON, THE ICE ON THE PRIPYAT RIVER SHATTERS.

THE MILLING ICE EATS AWAY AT THE BANKS, AND TAKES ALONG CONTAMINATED SAND.

[ ICE CRACKING ] SINCE THE LAST ICE AGE, THE SHIFTING RIVER HAS SHAPED AND RE-SHAPED THE LAND AROUND CHERNOBYL.

NOW, IT SPREADS RADIOACTIVE CONTAMINATION ACROSS THE FLOOD PLAIN.

THE WOLF TRAPS ARE SET FAR AND WIDE, AND TO PATROL THEM, BARBARA AND CHRISTOPH TEAM UP WITH LOCAL COLLEAGUES.

THEY CARRY DOSIMETERS THAT CONSTANTLY MONITOR RADIOACTIVITY, BUT THEY DON'T NEED PROTECTIVE GEAR AS LONG AS THEY DON'T DIG IN THE SOIL.

THAT WAS NOT THE CASE IN THE SPRING OF 1986.

[ CLICKING ] GREAT VOLUMES OF CONTAMINATED SOIL WERE REMOVED AND CARTED AWAY.

ENTIRE VILLAGES WERE BURIED -- A TASK THAT CONTINUES TODAY.

TENS OF THOUSANDS OF SO-CALLED 'LIQUIDATORS' WERE DEPLOYED TO CONTAIN THE HORROR OF THE NUCLEAR DISASTER.

EVENTUALLY, THE NUMBER OF EMERGENCY WORKERS SURPASSED 600,000.

SOME 150 VILLAGE COMMUNITIES WERE RELOCATED.

THE PEOPLE WERE MOSTLY RURAL WORKERS ON COLLECTIVE FARMS -- FARMS THAT ARE NOW ABANDONED.

TEN DAYS AFTER THEY SET THE TRAPS, CHRISTOPH GETS A MESSAGE FROM THE OTHER TEAM.

THEY'VE CAUGHT A WOLF.

[ SPEAKING GERMAN ] THE STATE OF THE WOLF POPULATION SAYS A LOT ABOUT AN ENTIRE ECO-SYSTEM.

AS THE TOP PREDATORS HERE, WOLVES ARE AN INDICATOR OF THE RADIOACTIVITY ACROSS ALL OF CHERNOBYL.

THIS WOLF HAS BEEN IN THE TRAP FOR A FEW HOURS.

HE IS FRIGHTENED, AND HE'S PLAYING DEAD.

BEHAVIOR LIKE THIS IS TYPICAL FOR A YOUNG WOLF.

BARBARA AND CHRISTOPH HAVE HEARD THAT MORE THAN 300 WOLVES LIVE IN THE ZONE.

IF TRUE, THAT WOULD MAKE IT THE HIGHEST WOLF DENSITY IN THE WORLD.

DO WOLVES MIGRATE TO THE ZONE BY THE HUNDREDS BUT DIE HERE BECAUSE OF THE RADIATION?

THAT'S THE MOST PROMINENT RUMOR.

[ BLOWS ] OR IS THE OPPOSITE TRUE?

WERE ALL THESE WOLVES BORN HERE BECAUSE THERE WERE NO HUMANS TO HUNT THEIR PARENTS AND THEIR PREY?

COULD IT BE THAT CONDITIONS ARE BETTER FOR THE WOLVES HERE THAN THEY ARE OUTSIDE THE ZONE?

AND, IF THEIR POPULATION IS EXPANDING, ARE THE RADIOACTIVE WOLVES SEEKING TERRITORIES BEYOND CHERNOBYL?

IT'S VITAL TO KNOW JUST HOW MANY WOLVES THERE ARE AND WHERE THEY GO.

THE PAW THAT WAS IN THE TRAP SEEMS TO BE FINE.

A RADIO COLLAR WILL ENABLE THE TEAM TO KEEP TRACK OF ITS MOVEMENTS.

FACE MASKS MATTER NOW -- THE WOLF'S FUR IS ALMOST CERTAINLY RADIOACTIVE.

[ BEEPING ] SIMPLE EXPOSURE TO THIS LOW LEVEL IS NOT THE PROBLEM.

BUT IF BARBARA OR CHRISTOPH INGESTED ANY RADIOACTIVE HAIRS, THEY WOULD BE POISONED.

THE SIZE AND STATE OF THE TEETH CONFIRM THAT THIS IS A YEARLING, BORN IN THE VERY HEART OF THE ZONE -- STRONG EVIDENCE OF AN INDIGENOUS POPULATION.

THE WOLF'S GPS TRANSMITTER WILL DELIVER DAILY PINPOINT DATA TO THE LOCAL SCIENTISTS WHO WILL SOON TAKE OVER.

BARBARA AND CHRISTOPH CALL THEIR WOLF 'BOI,' WHICH MEANS 'FIGHT' IN RUSSIAN.

THEY'VE SUCCESSFULLY LAUNCHED THE STUDY AND WISH BOI WELL.

WOLVES DIDN'T ALWAYS RECEIVE SUCH GOOD WILL.

BEFORE THE EXCLUSION ZONE EXISTED, THEY WERE RUTHLESSLY HUNTED HERE.

WOLVES HAVE FACED PERSECUTION ALMOST EVERYWHERE THEY ROAM.

[ GUNSHOTS ] ALPHA FEMALES WERE TARGETED, WHICH AFFECTED THE GENETIC HEALTH AND THE AGE STRUCTURE OF THE ENTIRE POPULATION.

BUT THE BIGGEST ENEMY OF THE WOLVES AROUND CHERNOBYL WASN'T THE HUNT.

IT WAS THE ALL-OUT ASSAULT ON THE WILDERNESS BACK IN THE 1920s.

THE DEFORESTATION AND DRAINAGE OF THE PRIPYAT MARSHES WAS A GIGANTIC NATIONAL EFFORT, ACCOMPANIED BY HEROIC PROPAGANDA.

CANALS WERE BUILT -- THOUSANDS OF MILES OF THEM.

TENS OF THOUSANDS OF SETTLERS CAME TO WORK ON THE NEW COLLECTIVE FARMS.

'LAND IMPROVEMENT,' AS IT WAS CALLED, WAS ALL ABOUT INCREASING FOOD PRODUCTION FOR THE SOVIET PEOPLE.

FROM THE 1920s UNTIL THE NUCLEAR DISASTER IN 1986, THIS LAND WAS ANYTHING BUT A WILDERNESS.

IT WAS A VITAL PART OF THE SOVIET UNION'S BREAD BASKET.

TODAY, THE LAND OUTSIDE THE ZONE STILL LOOKS THE SAME -- DRAINAGE CANALS AND WHEAT FIELDS STRETCHING TO THE HORIZON.

BUT WHAT BECAME OF THE CANALS AND WHEAT FIELDS INSIDE THE ZONE?

FORESTS AND FIELDS HAVE BEEN FLOODED, THANKS TO THE RETURN OF BEAVERS.

BEAVERS ARE NATIVE TO BELARUS, BUT THEY WERE AN OBSTACLE TO FARMING, AND SO WERE PERSECUTED LIKE THE WOLVES.

WITH THIS STRETCH OF THE PRIPYAT NOW FREE OF PEOPLE, IT DIDN'T TAKE LONG FOR BEAVERS TO REAPPEAR.

THOUSANDS OF THEM HAVE BEEN AT WORK DAY AND NIGHT, YEAR AFTER YEAR, DAMMING UP MAN-MADE CANALS, UNDERMINING DIKES, AND RESTORING THE MARSHES FOR AMPHIBIANS, FISH, SHELLFISH, INSECTS, OTTERS, MOOSE, AND WATERFOWL.

THE NOTORIOUS PRIPYAT MARSHES WERE ONCE SO VAST, THEY STOPPED THE ARMY OF GHENGIS KHAN.

NOW THE SWAMPS ARE BACK, THANKS TO A NUCLEAR REACTOR AND EUROPE'S BIGGEST RODENT.

ON HIGHER AND DRIER GROUND, VILLAGES HAVE BEEN OVERRUN BY OTHER FORCES OF WILD NATURE, RAVAGED BY SNOW STORMS AND FOREST FIRES.

CHERNOBYL'S WOLVES ARE PART OF A MUCH BIGGER STORY -- THE RETURN OF CULTIVATED LAND TO WILDERNESS, A CEASELESS, DYNAMIC PROCESS HAPPENING MUCH FASTER THAN ANYONE IMAGINED.

HERE, AGING FRUIT TREES COLLAPSE ONTO ROOFS.

REMNANT ORCHARDS ARE HARVESTED BY WILD BOAR, BEARS AND BADGERS.

RUINS DROWN IN WAVES OF GREEN.

GARDEN FLOWERS, ONCE TENDED WITH CARE, ARE LEFT TO RUN WILD.

AT THE ENTRANCE OF EACH VILLAGE, A ROUGH STONE RECALLS ITS NAME AND THE NUMBER OF PEOPLE FOR WHOM IT WAS HOME.

TWO MONTHS HAVE PASSED SINCE BARBARA AND CHRISTOPH LEFT THE ZONE.

THE MAN WHO'S TAKING OVER THE STUDY HAS RUN A WOLF MONITORING PROGRAM IN WILD WOODLANDS OUTSIDE THE ZONE FOR MANY YEARS -- PROFESSOR VADIM SIDEROVICH, OF THE NATIONAL ACADEMY OF SCIENCES OF BELARUS.

IT'S MAY, AND HE'S SEARCHING FOR THIS SPRING'S WOLF LITTERS.

Siderovich: THIS IS TYPICAL PLACE IN NALIBOKI WOODLAND WHERE LOCAL WOLVES GIVE BIRTH.

WHY?

FIRST, THIS PLACE IS HARDLY ACCESSIBLE FOR PEOPLE, BECAUSE IT'S EVEN HARD TO MOVE HERE.

SECOND, IT'S WELL-SHELTERED HABITAT, IT'S EASY FOR PUPS TO ESCAPE, TO HIDE UNDER THESE UPROOTED TREES.

AND THIRD, THERE IS ENOUGH WATER BECAUSE THERE IS STREAM NEARBY, SO, EVEN IN SUMMER DROUGHT, THERE IS WATER FOR PUPS TO DRINK.

Narrator: ANYONE WITH LESS FIELD EXPERIENCE AND LOCAL KNOWLEDGE THAN VADIM WOULD NEVER FIND A WOLF DEN IN THIS JUNGLE.

OVER THE YEARS, THIS MAN HAS LEARNED TO THINK LIKE A WOLF, TO KNOW WHERE THEY WILL FEEL SAFE.

[ PUPS GRUNTING ] THESE PUPS ARE JUST A FEW HOURS OLD.

VADIM WILL ONLY STAY FOR 20 MINUTES, SO THE WOLF MOTHER IS NOT KEPT AWAY FOR TOO LONG.

HE COUNTS THE NUMBER OF PUPS IN THE LITTER.

HE NOTES THE SEX OF EACH PUP AND CHECKS ITS HEALTH.

THEN HE PICKS UP HAIR SAMPLES FROM THE DEN FOR DNA ANALYSIS OF THIS POPULATION OUTSIDE THE ZONE... [ PUPS GRUNTING ] AND PLUCKS A FEW HAIRS FROM THE PUPS, AS WELL.

[ PUP CRIES ] VADIM WILL COMPARE THE DATA FROM THIS UNCONTAMINATED STUDY AREA TO THOSE HE WILL GATHER INSIDE THE ZONE.

THE PROFESSOR AND HIS TEAM WILL EXPLORE THE BELARUSIAN PART OF THE ZONE.

WHEN THE SOVIET UNION COLLAPSED IN 1991, THE REPUBLICS OF BELARUS AND UKRAINE DECLARED INDEPENDENCE, SEPARATING SCIENTISTS WORKING ON EITHER SIDE OF THE BORDER.

THE UKRAINIAN PART OF THE ZONE EXTENDS INTO THE INLAND DELTA LINKING THE RIVERS PRIPYAT AND DNIEPER.

THIS IS THE SITE OF THE CHERNOBYL NUCLEAR PLANT.

IN THE VERY SHADOW OF THE REACTOR, UKRAINIAN WOLF EXPERT MARYNA SHKVYRYA HAS BEGUN HER OWN INVESTIGATION OF THE WOLVES.

[ SHKVYRYA SPEAKING UKRAINIAN ] Narrator: THERE'S A PACK REGULARLY PATROLLING THE RIVER BANK, SHE SAYS.

JUST OPPOSITE, THE CITY OF PRIPYAT LIES HIDDEN.

IN A FIRST SURVEY, MARYNA EXPLAINS, JUST LOOKING AT TRACKS IN SUITABLY DRY WEATHER, SHE'S BEEN ABLE TO CREATE A MAP OF THE WOLF TERRITORIES IN THE UKRAINIAN PART OF THE ZONE.

SHE HAS DISCOVERED THAT THERE IS NO AREA OF THE ZONE WHERE THEY ARE NOT FOUND.

MARYNA SAYS THIS HAS ALWAYS BEEN A PERFECT HABITAT FOR THE WOLVES.

THE YEARS OF CULTIVATION IN THE SOVIET ERA WERE SIMPLY A TEMPORARY INCONVENIENCE.

SHE'LL USE THE SCAT FOR DIETARY AND GENETIC ANALYSIS IN THE LAB.

THE GHOST CITY OF PRIPYAT WAS ONCE A THRIVING METROPOLIS OF 58,000 PEOPLE, BUILT NEAR THE OLD JEWISH TRADING PORT OF CHERNOBYL.

IT MUST HAVE BEEN A PLEASANT PLACE TO LIVE BY ANY STANDARD -- A MODEL SOVIET CITY.

THIS IS THE CENTRAL SQUARE, WHERE ROSE AND JASMINE BUSHES AND TREES FLANKING THE AVENUES GROW IN UNBRIDLED PROFUSION.

IT'S A CITY THAT'S GREEN IN AN UNNERVING, UNINTENTIONAL WAY.

PRIPYAT WAS A YOUNG CITY, FULL OF LIFE, A CULTURAL CENTER.

WELL-EDUCATED AND PRIVILEGED ENGINEERS, AND SCIENTISTS FROM THE NUCLEAR PLANT, RESEARCH LABS, AND MILITARY INSTALLATIONS RAISED THEIR FAMILIES HERE.

NOW, THE WOODS ARE CROWDING INTO THE STREETS AND HALLS OF PRIPYAT, ATTRACTING MORE AND MORE WILDLIFE IN THEIR WAKE.

ON THE BELARUSIAN SIDE OF THE ZONE, PROFESSOR SIDEROVICH IS EXAMINING WOLF SKELETONS.

[ SIDEROVICH SPEAKING BELARUSIAN ] WITH HIS RESEARCHER, GRIGORI IVANOVICH, THE PROFESSOR COMPARES SKELETONS FROM INSIDE AND OUTSIDE THE ZONE TO DETECT POSSIBLE DEFECTS FROM RADIATION.

[ SIDEROVICH CONTINUES SPEAKING ] BUT THE ACTUAL FIELD RESEARCH STILL HAS TO WAIT UNTIL WINTER, WHEN THEY CAN SPOT WOLF TRACKS IN THE SNOW.

TODAY, AFTER A SNOW STORM, TWO MEMBERS OF THE STUDY GROUP ARE PREPARING TO DO JUST THAT.

ANOTHER WOLF HAS BEEN COLLARED IN ADDITION TO BOI -- A FEMALE YEARLING NAMED LARA.

ON THE ELECTRONIC MAP, THE RESEARCHERS FIND THE WOLVES' MOST RECENT GPS POSITION -- THE DESERTED VILLAGE OF KRASNASELYE.

THE GPS RECORD SHOWS THAT THE YOUNGSTERS HAVE SPENT THE BEST PART OF THIS YEAR TOGETHER, ALWAYS ROAMING AROUND THAT VILLAGE.

THAT MEANS THEY'RE SIBLINGS.

BUT ARE THEY PART OF A PACK?

FRESH TRACKS MAY GIVE THE ANSWER.

IN THE ZONE, ONLY A FEW MILES OF ROAD ARE BEING CLEARED OF SNOW, FOR POLICE AND RANGER PATROLS.

[ GEARS GRIND, ENGINE SPUTTERS ] THE BRIGHT SIDE IS THAT MANY ANIMALS NOW USE THESE ROADS, SO TRACKS AND WOLVES ARE EASY TO SEE.

AN INJURED MOOSE... THE WOLVES WILL SOON SPOT HER.

THIS WHITE-TAILED EAGLE IS WAITING FOR THEM TO DO THEIR JOB.

WOLF KILLS HELP EAGLES THROUGH THE WINTER WHEN THE LAKES ARE FROZEN AND THEY CAN'T FISH.

THE ABANDONED VILLAGE OF KRASNASELYE WITH ITS FIRE TOWER.

IF BOI AND LARA ARE PART OF A PACK, THIS COULD BE THEIR HEADQUARTERS.

TRACKS IN THE SNOW CONFIRM -- THIS IS THE BASE OF A BIG PACK.

[ WOLVES HOWLING ] KRASNASELYE IS SURROUNDED BY HIGH, OPEN GROUND.

THE SHELTER IT OFFERS, AND NEARBY WATER, MAKE THIS PLACE ATTRACTIVE TO WOLVES.

[ HOWLING ] THE RESEARCHERS COUNT TEN INDIVIDUALS, BUT THERE'S NO SIGN OF BOI AND LARA.

[ WOLVES HOWLING ] FROM THE ROOFTOPS, THE WOLVES SCAN THE LANDSCAPE FOR DEER, WILD BOAR, OR THE OCCASIONAL BISON CALF.

THE DEEP SNOW WITH ITS ICY CRUST GIVES THE WOLVES AN ADVANTAGE OVER THEIR HEAVIER PREY.

BUT FOR THIS MEAL, THE WOLVES DIDN'T EVEN HAVE TO HUNT.

THE CALF HAS SUCCUMBED TO THE RUSSIAN WINTER.

THE ADULTS ARE EUROPE'S HEAVIEST ANIMALS, TOO MIGHTY FOR WOLVES TO BRING DOWN.

BISON HAVE SURVIVED IN BELARUS AND POLAND SINCE THE ICE AGE.

ONCE IT BECAME OBVIOUS THAT OTHER WILDLIFE WAS THRIVING HERE, THEY WERE REINTRODUCED TO THE ZONE IN 1998.

[ WOLVES SNARLING ] EVENTUALLY, THE HERD CHASES THE WOLVES AWAY FROM THE CARCASS AND RETURNS TO MOURN THEIR LOSS.

THIS IS TYPICAL BISON BEHAVIOR.

THE THREE HERDS IN THE BELARUSIAN PART OF THE ZONE ARE GRADUALLY GROWING.

TO BELARUSIANS, THE BISON IS THE ANCIENT ICON OF THE WILD WOODS.

[ HELICOPTER BLADES WHIRRING ] UNTIL RECENTLY IN BELARUS, HUNTERS SHOT WOLVES FROM HELICOPTERS.

THIS IS NOW BANNED.

VADIM'S COLLEAGUE, GRIGORI IVANOVICH OF THE WOLF RESEARCH TEAM, IS A ZONE RANGER.

HE USED TO HUNT WOLVES HIMSELF, BUT NOW FLIES OVER THE ZONE SPREADING VACCINATION BAITS FOR WOLVES, FOXES, AND RACCOON DOGS TO PROTECT THEM AGAINST RABIES.

IN WINTER, ANIMALS CAN EASILY CROSS THE RIVER.

BOI AND LARA HAVE GONE EXPLORING SEVERAL TIMES.

THIS ABANDONED FACTORY ATTRACTS WILDLIFE BECAUSE IT OFFERS SHELTER IN HARSH WEATHER.

THE ENTIRE AREA IS CRISS-CROSSED WITH WOLF TRACKS.

[ OWL CALLING ] THESE BUILDINGS HAVE BEEN RADIATION-FREE SANCTUARIES INSIDE THE ZONE.

THE FALLOUT FROM THE ACCIDENT CAME DOWN WITH THE RAIN AND RAN OFF THE ROOFS INTO THE SURROUNDING SOIL.

BUT NOW, THE ROOFS AND RUSTING MACHINERY ARE WEAKENED BY EVERY HEAVY SNOWFALL, MAKING THEM FAR MORE HAZARDOUS THAN THE RADIOACTIVITY AROUND THEM.

FOR BIG HERBIVORES, WINTER IS A DESPERATE SEASON.

FOR WOLVES, IT'S JUST THE OPPOSITE.

HUNTING IS EASY NOW -- OR EVEN UNNECESSARY.

[ BIRDS CALLING ] A NUMBER OF SPECIES PROFIT FROM MEALS BROUGHT DOWN BY WOLVES.

RAVENS AND WHITE-TAILED EAGLES OFTEN LEAD THE RESEARCHERS TO THE WOLVES' KILLS.

RIGHT NOW, IN THE DEPTHS OF WINTER, THE EAGLES MAY ACT LIKE SCAVENGERS.

BUT THEY'RE REALLY TOP PREDATORS, JUST LIKE THE WOLVES.

SEEING THEM HERE IN SUCH NUMBERS IS ANOTHER INDICATION THAT THIS ECOSYSTEM IS IN ROBUST HEALTH.

IN CONTINENTAL CLIMATES, SPRING STARTS ALMOST OVERNIGHT.

CONVENIENT WINTER HIGHWAYS SUDDENLY TURN INTO IMPASSABLE BARRIERS.

EAGLES USUALLY NEST IN BIG OLD TREES, BUT THE ZONE OFFERS SOMETHING EVEN BETTER.

THE ZONE'S FIRE TOWERS ARE MANNED ONLY IN THE TINDER-DRY SUMMER MONTHS.

EAGLES NEED THEM IN THE SPRING, SO A TIMESHARE IS EASY TO ARRANGE.

NOW, THE MONTHS OF PICKING AT FROZEN CARRION ARE PAST.

RIVERS, OXBOWS AND LAKES ARE FREED AGAIN.

IT'S FISHING TIME.

WHEN THE SNOW MELTS IN THE CARPATHIAN MOUNTAINS, NEARLY 400 MILES TO THE SOUTHWEST, THE PRIPYAT RIVER SPREADS OUT.

IN THE HEART OF THE ZONE, IT CAN REACH A WIDTH OF ALMOST 10 MILES.

THE WATER LEVEL RISES BY 25 FEET.

WITH DIKES AND CANALS ALL BUT DESTROYED, THE PRIPYAT FLOODS THE ABANDONED FIELDS AND VILLAGES, ACCELERATING THE LAND'S RETURN TO WILDERNESS.

FOR A FEW DAYS, THE DESOLATION OF THE RANSACKED HOMES IS SOFTENED BY THE REBIRTH OF SPRING.

BLOSSOMING ORCHARDS ARE A LEGACY OF CHERNOBYL'S HAPPIER DAYS.

THE FRUIT TREES ARE A SWEET TEMPTATION FOR WILDLIFE.

IN THE AUTUMN, MANY ANIMALS WILL COME FOR A TREAT.

BUT NOW, VADIM'S RESEARCHERS HAVE COME HERE LOOKING FOR WOLF PUPS BORN IN THE ZONE.

THESE PUPS ARE ABOUT THREE WEEKS OLD.

THEIR CRIB IS AN OLD POTATO CELLAR.

[ IVANOVICH SPEAKING BELARUSIAN ] GRIGORI HAS FOUND THREE LITTERS -- FINAL PROOF THAT THERE IS AN INDIGENOUS POPULATION THRIVING IN THE VERY HEART OF THE ZONE.

SCIENTISTS, RANGERS, AND GUARDS ARE ONLY GIVEN A LIMITED TIME IN THE ZONE TO KEEP TOTAL RADIATION EXPOSURE DOWN TO A SAFE LEVEL.

BY CONTRAST, THIS MAN CARES FOR ANIMALS THAT ARE EXPOSED TO RADIOACTIVITY FOR AN EXTENDED TIME.

WHITE RATS ARE OFTEN STAND-INS FOR HUMANS IN POTENTIALLY DANGEROUS EXPERIMENTS.

AFTER THEIR EXPOSURE PERIOD, THE RATS ARE TAKEN TO A LAB FOR A SERIES OF TESTS.

SO FAR, IT IS NOT PROVING EASY TO ESTABLISH CLEAR LINKS BETWEEN LOW-LEVEL, LONG-TERM RADIATION AND HEALTH RISKS EVEN IN THE RATS, LET ALONE IN HUMANS.

BUT SCIENTISTS WILL CONTINUE TO MONITOR THESE RATS FOR ANY ILL EFFECTS.

ENVIRONMENTAL STUDIES DO NOT FOCUS ON INDIVIDUALS -- THEY TAKE A BROADER VIEW OF AN ENTIRE WILDLIFE POPULATION.

ONE IMPORTANT STUDY OF THE EFFECTS OF A RADIOACTIVE ENVIRONMENT ON WILDLIFE IS BEING CONDUCTED IN A HIGHLY CONTAMINATED AREA CLOSE TO THE REACTOR.

OUT HERE, FACE MASKS HAVE TO BE WORN.

THE DAY IS WINDY AND DUSTY, AND THE REACTOR IS LESS THAN A MILE AWAY.

THE WIND DIRECTION AT THE TIME OF THE EXPLOSION AND THE FIRE IS CLEARLY MARKED ON THE FALLOUT MAP.

THIS IS THE SITE OF THE INFAMOUS 'RED FOREST,' THAT IN THE MONTHS AFTER THE DISASTER TURNED RUSTY RED.

TODAY, THOUGH IT IS FAR FROM CLEAN, THE FOREST IS GREEN AGAIN.

A SIX-YEAR STUDY OF DORMICE LIVING IN THIS CONTAMINATED AREA IS ALSO SHOWING EVIDENCE OF NATURE'S RESILIENCE.

FOUR TO SIX PERCENT OF EVERY NEW GENERATION LIVING HERE SHOWS SLIGHT ABNORMALITIES -- TWICE THE RATE OF CLEAN AREAS.

FOR HUMANS, THIS RAISED LEVEL OF RISK IS UNACCEPTABLE.

BUT FOR DORMICE, THOUGH SOME INDIVIDUALS ARE AFFECTED, THE OVERALL POPULATION REMAINS HEALTHY.

IN FACT, THE DENSITY AND REPRODUCTION RATES ARE EVEN BETTER THAN IN CONTROL AREAS.

IS THAT ALSO TRUE FOR RADIOACTIVE WOLVES?

THE SCIENTISTS BELIEVE IT MUST BE.

BACK IN KRASNASELYE, VADIM AND GRIGORI ARE WORRIED.

FOR WEEKS, BOI'S AND LARA'S GPS TRANSMITTERS HAVE BEEN SILENT.

FORTUNATELY, THE WOLVES ALSO HAVE RADIO TAGS.

MAYBE THEY CAN BE SPOTTED FROM THE FIRE TOWER, WITH THE AID OF A TRACKING ANTENNA.

BUT THE LANDSCAPE IS ALMOST DESERTED -- NO SIGN OF BOI OR LARA.

THEY JUST GET A BRIEF GLIMPSE OF AN UNIDENTIFIED WOLF IN THE DISTANCE.

[ SPEAKING BELARUSIAN ] LOOKING IN THE OPPOSITE DIRECTION, JUST OVER THE BORDER IN UKRAINE, THE GHOST CITY OF PRIPYAT IS SUFFOCATING IN EXTREME SUMMER HEAT.

WITH TEMPERATURES OF 113° AT HIGH NOON, EVEN THE STREETS OF A LIVING CITY WOULD BE EMPTY.

BUT ORNITHOLOGIST SERGEY DOMASHEVSKY IS UNDETERRED.

THIS RAPTOR SPECIALIST IS MONITORING SEVERAL BROODS OF PEREGRINE FALCONS AROUND THE CITY.

[ INSECTS BUZZING ] IF RAPTORS ARE DOING WELL, THE POPULATIONS OF THEIR PREY MUST BE FINE, TOO.

[ FALCON CALLING ] THE NESTING SEASON IS THE IDEAL TIME FOR MONITORING THE STRENGTH OF A RAPTOR POPULATION.

SERGEY IS INTERESTED IN THE SIZE AND DEVELOPMENT OF FALCON BROODS AND IN THEIR SURVIVAL RATE.

[ CHICK SQUAWKING ] [ DOMASHEVSKY BLOWS ] HIS OBSERVATION IS THAT, IN THE ZONE, FALCONS AND EAGLES HAVE ESTABLISHED HEALTHY POPULATIONS.

FROM MANY OF PRIPYAT'S TOWER BLOCKS, THERE'S A VIEW OF THE REACTOR THAT ABRUPTLY FROZE THE CITY'S HISTORY.

CHERNOBYL'S MAN-MADE COOLING POND IS HIGHLY CONTAMINATED.

A LONG, NARROW CAUSEWAY LINKS THE SHORE TO A SMALL ISLAND.

GIANT CATFISH, EIGHT FEET LONG AND MORE, THRIVE HERE.

THEY'RE TOO BIG TO BE HUNTED, EVEN BY THESE HUGE WHITE-TAILED EAGLES.

THE STUNNING SIZE OF THE POND'S CATFISH AND CARP HAS NOTHING TO DO WITH RADIOACTIVITY, BUT RATHER WITH THEIR AGE.

THE FISH KEEP GROWING ALL THEIR LIVES.

CATFISH CAN LIVE FOR ALMOST A CENTURY.

SINCE THE MELTDOWN, THESE SURVIVORS HAVE LIVED UNDISTURBED IN THE SHADOW OF THE REACTOR.

OUT ON THE SMALL ISLAND IN THE MIDDLE OF THE POND, WHITE-TAILED EAGLES COME TO EAT THEIR PREY.

THESE AMUR CARP LOOK TO HAVE WEIGHED 30 TO 40 POUNDS.

THE EAGLES MUST HAVE DRAGGED THEM ASHORE.

THEIR TALON MARKS CONVEY THE POWER OF THESE BIRDS.

THE RESEARCHERS WANT TO CHECK HOW CONTAMINATED THE FISH BONES ARE.

[ BEEPING ] THESE FISH BONES SHOULD NOT BE TOUCHED WITH BARE HANDS.

WHAT THIS CONTAMINATION DOES TO THE EAGLES IS STILL NOT KNOWN.

SUNRISE OVER THE OLD CHERNOBYL RIVER PORT.

THE ACCIDENT LEFT MANY SHIPS STRANDED.

ONLY A FEW HULKS REMAIN.

FROM HERE, THE RESEARCHERS TAKE A TRIP DOWN THE PRIPYAT, THROUGH THE INLAND DELTA, TO ITS CONFLUENCE WITH THE RIVER DNIEPER.

THIS IS ONE OF EUROPE'S LARGEST AND MOST CRUCIAL HABITATS FOR WATERFOWL.

FLOWING WATERWAYS HAVE LONG BEEN CLEAR OF RADIATION.

OUT HERE, THE FISH CAN SAFELY BE EATEN, EVEN BY HUMANS.

COUNTLESS WOODED AND SANDY ISLANDS OFFER IDEAL BREEDING PLACES FOR BIRDS.

THERE ARE COLONIES OF SAND MARTINS, CORMORANTS, CRANES, AND HERONS -- AROUND 120 SPECIES IN ALL.

[ BIRD CALLING ] ONE BIRD IN PARTICULAR HAS BEEN ATTRACTED TO THE ZONE -- THE BLACK STORK, WITH ITS MARKED PREFERENCE FOR DESERTED LANDSCAPES WITHOUT HUMAN DISTURBANCE.

AS SACRED PLACES, CEMETERIES HARBOR THE LAST REMNANTS OF UKRAINE'S PRIMEVAL OAKS -- TREES BIG ENOUGH TO SUPPORT A STORK NEST WEIGHING A TON.

ON ONE OFFICIAL DAY EACH YEAR, FRIENDS AND RELATIVES COME TO VISIT THE DEAD.

THE REST OF THE YEAR BELONGS TO THE STORKS.

[ MACHINE BEEPS ] LATE SUMMER -- VADIM SIDEROVICH TRIES HIS LUCK AGAIN, HOPING TO SPOT BOI AND LARA.

A STRETCH OF ROAD NEAR KRASNASELYE IS THE BORDERLINE OF THE PACK'S TERRITORY.

THE ROAD IS ALWAYS DOTTED BY FRESH SCAT MARKS, ESPECIALLY THIS BRIDGE OVER AN OLD DRAINAGE CANAL.

VADIM HAS PICKED UP BOI'S SIGNAL FROM TWO POSITIONS.

HE MUST BE NEARBY, SOMEWHERE DOWN THIS ROAD.

SUDDENLY, A HUGE WILD BOAR CROSSES THE ROAD, FOLLOWED BY A WOLF WEARING A COLLAR.

IT'S BOI.

ON HIS WOLF PATROLS, GRIGORI NOTICED A STRANGE CHANGE IN THE LANDSCAPE, AND HE WANTS TO CONSULT VADIM.

MANY BEAVER DAMS HAVE DECAYED AND ARE DESTROYED.

IN SOME AREAS, THE WATER LEVEL IS SINKING, AND GRIGORI SUSPECTS THAT WOLVES ARE INVOLVED.

[ MEN CONVERSING IN BELARUSIAN ] TO VADIM, IT'S A FAMILIAR SCENARIO.

THE WOLVES HERE IN THE SOUTH, HE SAYS, ARE QUITE A BIT SMALLER THAN THE WOLVES FARTHER NORTH.

SO THEY KEEP RISKY ATTACKS ON BIG ANIMALS TO A MINIMUM -- INSTEAD, THEY TARGET BEAVERS, WHICH ARE EASY TO HUNT AND ABUNDANT.

[ SIDEROVICH SPEAKING BELARUSIAN ] IN VADIM'S CONTROL AREA, BEAVERS ACCOUNT FOR 60% OF THE WOLVES' DIET.

SO WOLVES ARE SLOWING DOWN, AND EVEN REVERSING, THE RETURN OF THE SWAMPS.

SINCE THE LAST ICE AGE, THIS LAND WAS ROAMED NOT ONLY BY BIG HOOVED ANIMALS LIKE MOOSE, DEER AND BISON, BUT ALSO BY WILD HORSES.

THE LAST GENUINE WILD HORSE IN UKRAINE WAS KILLED IN 1879.

[ HORSE WHINNIES ] NOW, THE LAST SPECIES OF WILD HORSE LEFT ON EARTH IS THE PRZEWALSKI, WHICH ONLY SURVIVED IN CAPTIVITY.

GROUPS OF PRZEWALSKIS HAVE BEEN RELEASED HERE SINCE THE 1990s, TO HELP RESTORE THE LAND'S ORIGINAL BIODIVERSITY.

AT THE RATE THEY HAVE BEEN REPRODUCING, THERE SHOULD BE ABOUT 200 INDIVIDUALS.

BUT UKRAINIAN POACHERS HAVE LEFT JUST 60.

DURING THE 20th CENTURY ALONE, HUMAN HISTORY DEALT DEVASTATING BLOWS TO THIS WETLAND WILDERNESS.

IT'S BEEN RAVAGED BY THE BATTLES OF TWO WORLD WARS AND THE IMPROVEMENT CRAZE OF THE STALIN ERA.

IRONICALLY, THE WORLD'S BIGGEST NUCLEAR DISASTER HAS TURNED IT INTO A UNIQUE REFUGE FOR ENDANGERED SPECIES.

[ IMITATING WOLF CALL ] EACH SEPTEMBER, PROFESSOR VADIM SIDEROVICH IS OUT IN THE FIELD TO CALL THE YOUNG WOLVES.

IT'S A WAY TO SEE EACH LITTER AND ESTIMATE THEIR SURVIVAL RATE.

VADIM AND GRIGORI SYSTEMATICALLY COVER THE ENTIRE BELARUSIAN PART OF THE ZONE.

[ ENGINE ROARS, BRAKES SQUEAL ] [ IMITATING WOLF CALL ] WOLVES HAVE BEEN VADIM'S LIFE.

HE HAS WORKED AND LIVED WITH THEM FOR DECADES.

HE SPEAKS THEIR LANGUAGE.

[ MAKING WOLF CALL ] WITHIN A WEEK, VADIM IDENTIFIES THE TERRITORIES OF 17 PACKS.

[ MAKING WOLF CALL ] [ WOLVES RETURNING CALL ] Siderovich: FROM THIS INFORMATION, I MEAN, ABUNDANCE OF WOLF TRACK ON LOCAL ROAD, I COULD ASSUME THAT THERE ARE NOT SO MANY WOLF AS IT HAD BEEN CLAIMED BY LOCALS -- 300 INDIVIDUALS OR MORE.

BY COMPARING SIMILAR INFORMATION, SIMILAR OBSERVATION DONE IN NALIBOKI WOODLAND, ON THE SAME AREA AS CHERNOBYL ZONE, BELARUSIAN PART, I COULD ASSUME THAT PLAUSIBLE MAXIMUM OF WOLF POPULATION NUMBER IN CHERNOBYL ZONE IS 120.

SO, 25 YEARS AFTER THE CHERNOBYL ACCIDENT, THE WOLF POPULATION IN THE ZONE APPEARS TO BE THE SAME AS IN A CLEAN REFERENCE AREA -- NO MORE, NO LESS.

FOR HUMANS, THIS LAND IS LOST.

BUT IN A STRANGE TWIST OF FATE, WOLVES MAY HAVE GAINED AN UNLIKELY CHANCE TO SURVIVE IN PEACE IN THE SHADOW OF A NUCLEAR DISASTER.