Natural World (1983) s25e05 Episode Script

Deep in the heart of South America lies one of the most spectacular secrets of the natural world Iguacu one of the planet's largest waterfalls It's a fearsome display of the raw power of water but it also has a gentler side A vast and continuous cloud of fine spray rises up over the surrounding trees This refreshing moisture nurtures a very special section of rainforest a biological hotspot for some of South America's most amazing animals But Iguacu National Park is a refuge fighting for survival Dedicated teams work tirelessly to guard it from poachers and illegal loggers Drastic action is needed but this is a hard place to police In the wet season Iguacu can have up to 300 individual falls draining from the hundreds of kilometers of surrounding forest Can this magical place be saved? Around 120 million years ago the rupture of the supercontinent of Pangea led to the creation of Africa and South America Lava bursting through hardened into giant blocks of fine-grained basalt This is the rock from which the Iguacu waterfalls have been sculpted grain by grain Basalt is such a hard rock that it erodes very slowly leaving behind a line of cliffs up to 82 metres tall At one point 7 miles long Iguacu's horseshoe-shaped falls are nearly 3 times the size of Niagara In the wet season enough water flows over the edges every day to supply the city of London for more than a year The torrent could drag you to your death but Great Dusky Swifts fly right through it Behind the wall of water they are safe from predators Most other animals have to make do with the spray-drenched forest which surrounds the falls Tucked away, some 15 metres up in the canopy lives one of Iguacu's most successful mammals the ring-tailed coati It's risky place to raise young but it's a lot safer than on the ground Jaguars the mightiest cats of the Western Hemisphere, still roam here But they're in steep decline Good news for the coatis perhaps but bad news for Iguacu National Park These forests used to stretch back from most of Brazil's Atlantic coast-line Now only 7% of this unique Atlantic rainforest is left Iguacu straddling the border between Brazil and Argentina is one of the last refuges for the outstandingly rich and endemic wildlife of the area known locally as the 'Mata Atlantica' In the eighties Iguacu was given World Heritage status but it was steeped in folklore long before this A native legend tells of Naipi daughter of a tribal chief a girl so beautiful that the Iguacu River would stop to admire her Tarob¨¢ a brave young warrior fell in love with Naipi, and won her heart With each passing day their feelings grew stronger But the chief had already chosen Naipi to be sacrificed to honour their ruling serpent god, M'boi The night before the sacrifice the couple made their escape Little did they know that the god M'boi was watching in fury The waters raged with the Gods wrath and a gigantic gorge opened before them Thus the demise of Naipi and Tarob¨¢ was the creation of the Falls of Iguacu In what is now called the Devil's Gorge it is said their spirits remain forever Each Spring new life emerges from this bewitching place Flocks of up to three thousand swifts come here to breed The birds clamber over each other as they attempt to show themselves off to best advantage On these precipitous cliffs the ability to Hang On might be the most attractive trait of all Despite their numbers at the falls they have been little studied and their courtship behaviours are not fully understood The acrobatics continue for several days on both sides of the cascade Until eventually the birds pair off But nothing about life on the falls is easy the female allows the male to court her but often rejects him over and over He offers her some useful nesting material for her hard basalt hollow but even that doesn't do the job The flirting eventually pays off and it's time for the flying circus to begin family life While the swifts are just starting to build their nests the baby coatis are growing too boisterous to stay inside theirs They're three and a half weeks old and getting a taste for adventure The mother has two more weeks teaching them the ropes on her own Like their mother the babies need to become excellent climbers it's vital for finding food but also for escaping from predators For now, though it's one step at a time Despite the occasional mishap the youngsters quickly cotton on Long tails help to balance while strong, sharp claws grasp the bark as they literally hang on for their lives And, if they ever lose their nerve help and encouragement is at hand After about 6 weeks isolated with their young mother coatis reassemble into large social groups that can number more than 60 individuals Even after short periods apart coatis engage in excitable greetings and groom each other At last, relief from looking after the kids mothers take turns running a cr¨¨che Some go off looking for food while others watch over the unruly cubs Iguacu appears idyllic but scientists in the park fear that many treasures have already been lost There is little knowledge of life in the forest beyond the falls Both Brazilian and Argentine scientists are working hard to put that right Ricardo Melzew is part of a special Jaguar project funded by several government departments They've discovered that in the last 15 years Iguacu's jaguar population may have suffered an 8 fold decrease in numbers Researchers use cameras to spy on these elusive predators An infrared sensor is tripped by passing animals producing snapshots of jaguars' secret lives These can tell Ricardo and the team a good deal: We use a camera trunk to track the cats especially the spotted ones like the jaguar Each jaguar has unique spot patterns like fingerprint so based on those we can tell exactly how many individuals there are Back at the lab the researchers face the challenge of interpreting all their data Do Iguacu's most powerful feline predators stand any chance of survival? Iiaria Agostini thinks the evidence from photos, feces and footprint casts all points one way Jaguars are disappearing first and foremost, because of hunting There are many records of jaguars killed by poachers who shoot them in order to sell their skin or just for the thrill of killing a jaguar But the most recent snaps offer some encouragement They've identified a male-female pair Extremely good news as the park population is estimated at a mere twelve individuals Maybe this pair will breed But it's not just jaguars that scientists want to protect This is a special bird in its element at Iguacu The snail kite depends on water to supply its main food source juicy amphibious apple snails The kite may eat as many as 70 snails a day so it regularly patrols the fast-flowing water Some rapids are too powerful for fishing though the kite seems able to cope with the strong currents at the edge of the falls Few birds of prey are this specialized The ultra-rounded beak is perfectly shaped for scooping out and lacerating the muscle tissue that binds snail to shell With the rainy season is underway activity around the falls is hotting up Red-rumped caciques are well into a huge nest-building programme The males do the hard graft and the females keep tabs on them An elaborate series of knots secures the long tear drop shaped nests to the tree With dozens of couples living in a single tree the occasional dispute is unavoidable Desperate to finish in time a cacique may steal a neighbor's supplies to get ahead But community life has its advantages Large colonies mean better protection when the nests host precious offspring After the clamour from the cacique colony subsides yet another of Iguacu's residents joins the wait for a new generation A mother caiman listens carefully Nearby, her nesting mound contains up to sixty eggs This is the sound she's been waiting for The babies synchronize their emergence by calling to each other while still inside the egg The mother caiman has protected this mound for 90 days Now, by hatching all at once her babies have further reduced each individual's chances of being picked off by monkeys, lizards or birds The hatchlings head directly towards water where they will remain under their mother's guard for several months But tonight, they've been spotted Fortunately they're being hunted by park biologists carrying out their annual caiman census Just as jaguars can tell scientists about the overall health of the forests broad-snouted caiman numbers are a good indicator of water quality in the park Caiman are very vulnerable to pollution The main threat to them, however, comes from people Many caiman are hunted for meat but the broad-snouted caiman is especially targeted for its unique skin used to make fine leather goods When Justo Herrera and the Argentine National Park team began the study ten years ago the caiman population was alarmingly low "The drop in the Caiman population was due to heavy poaching in the area Now, there are more park rangers on patrol This seems to have deterred hunters letting the population begin to recover" These are small but hopeful signs for Iguacu's future The swifts are also doing well If the sun is shining the swifts will be on the wing It's summer and temperatures have risen by around 10 degrees Celsius The mist cloud creates a super-humid micro-climate around the falls but the swifts have the ultimate antidote for the oppressive heat The high-pressure showers are not only cooling they help rid the birds of parasites Feathers need to be in top condition for their aerial stunts and long hours on the wing The swifts compete for the nooks and crannies under the falls which will make the best nest sites Nest-building is soon under way Materials include plants, feathers and moss from all around the falls But it's their own saliva that will help glue the nest to the slippery rock In the carefully prepared crevice the swift lays just a single egg, guarded with utmost care Virtually no nest predator can get up here so the swifts have no need to reproduce in great quantity The eggs take an unusually long time to hatch possibly because of the chilly conditions in the dank hollows Nearby, the 3-month-old coati cubs have become intrepid explorers They're nimble climbers now, and growing fast which means they're in constant search of food But their playful antics can also put them into grave danger it's not wise to annoy some of the jungle neighbours The South American rattlesnake is one of the most poisonous of the rattlers its venom can easily kill a human let alone a young coati But when hot on a scent the cubs often take little notice of other creatures around them The bone-chilling rattle should be enough to send anyone running But young coatis are both naive and curious The rattle is the warning Provoking it is a deadly game to play for the youngsters Its neuro-toxic venom invades and disrupts the victim's nervous system The coati cubs survive another day but the fate of Iguacu as a whole remains less certain Iguacu is a large island of rainforest surrounded by a huge sea of farmland The long term impact of the encroaching areas remains to be seen In a pioneering expedition to find out more scientists are penetrating deep into the little-known heart of Iguacu and the pristine Floriano River This is as far as the chopper will take them The team is led by National Park biologist Alcides Rinaldi and visiting specialist Carolina Ribas They hope to find traces of the giant river otter a species native to the area whose current status is unknown They're accompanied by Adaildo Policeno who once made his living as poacher For team-leader, Rinaldi this is unknown territory "This expedition is a rare chance to explore an area where very few people have ever set foot It's totally remote closed off to visitors So it can give us a look at how this whole region must have been long ago" Some of the local inhabitants are agitated by the group's arrival These are so-called 'killer bees' a dangerous hybrid descended from escaped African bees originally brought to Brazil for honey production Their aggressive nature and the number of stings sustained by the team threatens to end the expedition before it's even started The river offers an escape from the harmful bees and the oppressive summer heat The group heads off as quickly as possible The biologists are looking out for any signs of the 1.
8m long giant otter But expert, Caroline Ribas believes this part of the river isn't quite right "I think there's too much current here to be giant otter habitat The water is very clear and there aren't many large fish So far we've seen a lot of common river otter marks but no sign of any giant otter I'm hopeful though!" It's so remote here that it's possible to see very rare animals even the fugitive jaguar can prowl here in relative safety The name jaguar comes from the indigenous word "yaguara" meaning "the beast that kills his prey in one leap" So even large mammals must remain vigilant in this dense forest Excellent hearing and a keen sense of smell will help keep this tapir out of trouble The Brazilian or lowland tapir has a unique crest along the back of its neck thought by some scientists to be a protection from jaguar attacks Its ancestry links it to the primitive horse and the rhino Despite appearances tapirs are good runners and have extremely tough skin If frightened or attacked they will rush into water to escape A 200kg tapir would be several days' worth of food But only an experienced jaguar would succeed in bringing one down Most jaguars don't get that far Along the rivers in the Iguacu heartland are some of the greatest concentrations of butterflies on earth rivaling the spectacle of the Amazon rainforest Scientists reckon that there may be over 800 different species in the park but so far only 257 have been identified They gather in huge numbers on damp ground because these are the best places to absorb essential salts and minerals Unfurling their straw-like tongues they suck up huge amounts of water Inside their bodies the necessary minerals are filtered out and the surplus river water is steadily flushed out at the other end These gatherings are almost exclusively male And it's competitive The males pass their mineral strength to the female when they mate So filtering more water now will increase the chances of passing on his genes Along the nearby Floriano River the search for the giant otter continues The team has paddled and hacked its way through a 40km obstacle course Finally they reach the place where ex-hunter, Adaildo Plicenoa remembers seeing a giant otter six years ago "Here, between the first and second waterfalls I saw a giant otter sitting on this rock He was looking up in that direction The water was high and he was sitting right here eating a fish" "It caught my attention because it had a white mark here "Was it near its mouth, or on the chest?" "More on the chest Historically giant otters were easier to find in the rivers of Iguacu Social and gregarious they live and hunt in packs earning them the nickname of 'water wolves' But in recent decades sightings became fewer and fewer until, in the late 1980's the otters seemed to disappear altogether Along the banks Carolina Ribas and the team find only traces of the smaller, common otter "Right here we've found some common otter mucous they use it to mark their territory Look at this here Here on the bank you can see really clearly where the otters have left claw marks" There's an otter's holt but it also belongs to a common otter The whereabouts of its elusive giant cousin remain a mystery The Floriano River starts and ends on protected land making it one of the purest waterways in Iguacu If the giant otter is to be found anywhere it should be here They check each stretch of the river for likely spots "We've reached a part of the Floriano river that's deeper and calmer any of the sections we've encountered so far It's around 4 and a half feet deep That means there are probably more fish here which would make it a more likely place to find giant otters Unfortunately we haven't found any traces of them yet" "Not finding a single sign is a disheartening end to the expedition Giant otters are very sensitive to pollution Could contaminants from the surrounding farmland have already seeped into the park? It's a reminder of how easily the balance of nature in this island of rainforest can be upset The arrival of the annual rains can be quite disruptive too Some animals benefit from the extra food on offer But a violent rainy season raises river levels at an alarming rate Recently, Iguacu experienced intense rainfall The flow over the falls reached a staggering 17,000 cubic meters per second one of the highest since records began Normally, the falls provide unparalleled protection for the great dusky swifts Now the waters threaten to destroy this year's brood and take down the adults too Life becomes both a matter of endurance and luck Here, the river has risen an incredible 20 metres nearly swallowing some of the falls The swifts are resilient and within days they are back in action, re-building their lives The coatis take the rainy season in their stride Their life is spent high and dry The coati diet is very varied and much of what they need can be found in the trees But they do get their feet on the ground to find protein-rich invertebrates and their elongated up-turned snout is ideal for rooting them out For digging into the best bug hideaways their climbing claws come into their own This year's cubs are discovering that Iguacu's forests offer a fantastic variety of fruit No wonder coatis are doing well here They can get around quickly thanks to a reversible ankle joint which gets them down trees head-first and they are learning fast both from each other and their adult chaperones For now the pack travels as a group But before the youngsters reach their third year things will change The females will stay with their mothers but the males will have to peel off on their own Young male coatis need to make the most of the precious time spent under their mother's wing At sundown, when the coatis are tucked up different characters emerge around the falls On the forest floor one of the true terrors of the night Already the size of a human hand the tarantula can take on prey even larger than itself Hairs on the tarantula's body form an array of sensory hunting equipment They allow it to detect heat chemicals and vibrations in the air A perfect predator Just one of the helpless, blind mice would be a perfect meal enough to satisfy the tarantula for several days Babies everywhere are under threat The nests at the cacique colony are now full of chicks Adults are on full alert even before the first rays light up the forest Red-rumped caciques have plumage to match their noisy nature As the chicks begin to stir their parents begin the daily grind to feed them Some of the caciques have already lost chicks to predators but many nests still contain one, two or even three hungry mouths desperate for an insect breakfast But they always keep an eye out for danger Their enemy, the Toco toucan, doesn't need camouflage It's big, and it's pushy The combined efforts of the cacique colony are no real match A cacique chick is just a protein supplement in the toucan's fruity diet But in mere seconds a cacique's season of labour is lost The Park authorities can also find their hard work undermined Poachers are at work in Iguacu and Brazilian and Argentine rangers join forces to root them out Apol?nio Rodrigues, Vice-President of the Brazilian park scans the riverbank for any tell tale signs of infiltration Argentine head ranger, Jorge Cieslik, shares command There's no telling what they might find poachers can be heavily armed Rodrigues and Cieslik are sure they're on the right track "Clearly there is a camp nearby.
" "There is a path cleared that splits off We know there's nothing in one direction but in the other direction it's likely we'll find the camp "When we first got here¡­" "We heard firecrackers when we got here That's their accomplices warning them So now we know they are in there But taking the suspects by surprise will not be easy The rangers advance cautiously in this remote patch of forest there's no back-up The ambush is successful but the rangers know these are the little guys Local people are poor Hunting, although illegal can bring in many times the minimum wage The rangers collect up evidence which includes some dangerous, primitive weapons and the remains of a rare white-lipped peccary "This is a homemade canon, old-fashioned style Our friends here set them up all around the park" "This one's been well-used already They set up a wire, and when an animal trips it" "¡­it pulls this trigger here" "Hunting has always been a problem in the park It has increased because it's so lucrative People no longer hunt just for themselves; they sell kills to dealers or sometimes they work on special order for people in the area" Now the park rangers themselves have to use increasingly radical and sometimes violent tactics In this tranquil place it seems to be the only way to give Iguacu's wildlife a fighting chance Around the falls the coatis numbers have become more concentrated maybe taking advantage of the decline in big cats such as the jaguar The ground has become a much safer place for the young males to spar This is practice, perhaps for when they need to fight for the right to mate with females Soon the young males will have to leave already they are testing their independence They've already started to build their own sleeping nests near the group It's time to reaffirm group bonds and settle in to replenish their energy for the adventures ahead The worst of the rainy season is over and the falls at Iguacu are back to normal The swifts have recovered from the raging flood and the single chicks are growing strongly They're demanding little things hungry for insects that the parents catch in mid-air For weeks the chick has observed his parents' fearless flight path But that won't make its maiden plunge any less harrowing Mum and dad form a safety net while the chick tests its wings Then comes the day of reckoning The falls are a formidable place to live; a gated fortress to which only the swifts have the key The grand falls of Iguacu are a world monument That status has helped to protect the remnant of Atlantic rainforest that lies behind It is sobering to think that without this fantastic spectacle an entire wild community might already have disappeared