0:00:43 > 0:00:48The South Pacific Islands are the most isolated in the world.
0:00:53 > 0:00:57Some are more than 4,000 miles from the nearest continent.
0:01:02 > 0:01:05The odds against any life reaching these islands,
0:01:05 > 0:01:08and flourishing, were once minute.
0:01:11 > 0:01:13But no matter ho remote they may be,
0:01:13 > 0:01:15all have been colonised.
0:01:19 > 0:01:21First by plants and animals...
0:01:22 > 0:01:25..and then by humans.
0:01:27 > 0:01:29So who were those castaways
0:01:29 > 0:01:33and how did they ever reach these far-flung islands?
0:01:46 > 0:01:50More than twice the width of the Atlantic Ocean,
0:01:50 > 0:01:53the South Pacific is 10,000 miles wide.
0:02:00 > 0:02:04Many of the pioneers who made it to the most easterly islands
0:02:04 > 0:02:07set off from its far-western corner.
0:02:13 > 0:02:16And, for most, New Guinea was the launch pad.
0:02:17 > 0:02:20Three times the size of Britain,
0:02:20 > 0:02:23this is the largest tropical island in the world...
0:02:24 > 0:02:27..and the richest in animal life...
0:02:31 > 0:02:34..with some truly eye-catching residents.
0:02:37 > 0:02:40Like this Goldie's Bird of paradise.
0:02:42 > 0:02:44Never filmed before,
0:02:44 > 0:02:49Goldie's are just one of New Guinea's 38 species of bird of paradise -
0:02:49 > 0:02:52all famed for their spectacular plumage.
0:02:57 > 0:03:01Keen to show his impressive feathers to an attentive female,
0:03:01 > 0:03:04the male clears the stage.
0:03:09 > 0:03:13Now he's ready for a spot of serenading.
0:03:14 > 0:03:18BIRD SINGS
0:03:22 > 0:03:26Females may be dull looking but they are very picky.
0:03:34 > 0:03:36His solo fails to impress.
0:03:37 > 0:03:41A second male arrives and takes centre stage.
0:03:41 > 0:03:45But, rather than fight, they strike up a duet.
0:03:45 > 0:03:48BIRDS SING IN UNISON
0:04:05 > 0:04:10This show of strength finally gets her attention.
0:04:11 > 0:04:16The best-dressed Goldie gets the girl.
0:04:22 > 0:04:25But while his feathers may have secured him a mate,
0:04:25 > 0:04:29they're not strong enough to carry him off the island
0:04:29 > 0:04:32and further east across the South Pacific.
0:04:32 > 0:04:37Birds of paradise sacrificed flight efficiency for flights of fancy.
0:04:43 > 0:04:48So who did manage to colonise the South Pacific?
0:04:53 > 0:04:56New Guinea's enormous landscape
0:04:56 > 0:05:00is carved up into thousands of isolated valleys.
0:05:09 > 0:05:12Each shelters huge numbers of potential colonisers.
0:05:18 > 0:05:24Amazingly, one in twenty of the world's insect species may live here.
0:05:30 > 0:05:34As well as almost 300 species of mammal,
0:05:34 > 0:05:38like the bizarre, egg-laying, long-nosed echidna.
0:05:45 > 0:05:50There are even kangaroos that have taken to the trees.
0:05:53 > 0:05:57Although somewhat precariously!
0:05:57 > 0:06:01Did any of these animals ever travel east to other islands?
0:06:04 > 0:06:09Around 300 species of reptile thrive within this hot house,
0:06:09 > 0:06:14including the ubiquitous mourning gecko.
0:06:17 > 0:06:19It is a highly-adaptable creature
0:06:19 > 0:06:25but did it have the tools, stamina and luck to survive being a castaway?
0:06:32 > 0:06:34One animal certainly did.
0:06:34 > 0:06:35DRUMS BEAT
0:06:35 > 0:06:37Humans.
0:06:37 > 0:06:40THEY CHANT
0:06:43 > 0:06:48Despite only arriving in New Guinea 40,000 years ago,
0:06:48 > 0:06:54humans were soon established throughout the island's maze of hidden valleys.
0:06:55 > 0:06:59Today, these people are known as Papuans
0:06:59 > 0:07:02and together speak over 700 different languages -
0:07:02 > 0:07:05more than any other island on Earth.
0:07:07 > 0:07:12Yet, despite their mastery of the island,
0:07:12 > 0:07:15there was one creature they lived in awe of -
0:07:15 > 0:07:19the giant man-eating crocodile.
0:07:28 > 0:07:32Even today, young men must endure a brutal initiation ceremony,
0:07:32 > 0:07:37to acquire the strength and guile of these giant reptiles.
0:07:41 > 0:07:44THEY MARCH AND CHANT
0:07:47 > 0:07:53The chief shaman calls out to the crocodile gods, asking for their blessing and protection.
0:07:59 > 0:08:04The tribesmen form the sinuous shape of a moving crocodile.
0:08:06 > 0:08:11At the rear, the crocodile's tail, a court jester lightens the mood.
0:08:12 > 0:08:18Momentarily, for what follows is a gruelling and potentially lethal rite of passage.
0:08:19 > 0:08:24These young men will be mutilated, to resemble crocodiles.
0:08:30 > 0:08:34The boys are led into the spirit house,
0:08:34 > 0:08:36running the gauntlet of blows from their elders.
0:08:41 > 0:08:46Inside, they find sharpened lengths of bamboo.
0:08:48 > 0:08:51The sacred act of scarring is about to begin.
0:09:03 > 0:09:06The ritual is a closely-guarded secret.
0:09:06 > 0:09:10DRUMS BEAT TO A CRESCENDO
0:09:12 > 0:09:15BOY SCREAMS, MEN CHANT
0:09:18 > 0:09:20Their cuts are thoroughly cleaned.
0:09:20 > 0:09:22Killer infections are a real danger.
0:09:27 > 0:09:32They go in as boys but they come out as men - crocodile men -
0:09:32 > 0:09:37with the power to summon the great reptiles.
0:09:43 > 0:09:48The scars on their back represent the animal's scales...
0:09:53 > 0:09:57..while their chests have become the crocodile's eyes.
0:09:59 > 0:10:04If the animal you most fear might be watching your every move,
0:10:04 > 0:10:07any act of appeasement is worth trying.
0:10:14 > 0:10:20And New Guinea wasn't the last stop for saltwater crocodiles in the South Pacific.
0:10:26 > 0:10:28Millions of years ago,
0:10:28 > 0:10:32these powerful reptiles had already begun their push eastwards.
0:10:41 > 0:10:43For any animal castaway,
0:10:43 > 0:10:47the first hurdle would have been the 60-mile stretch of water
0:10:47 > 0:10:53that separates New Guinea from the next group of islands - the Solomons.
0:11:00 > 0:11:04Instead of one dominating island, like New Guinea,
0:11:04 > 0:11:08the Solomons are made up of almost a thousand smaller jewels,
0:11:08 > 0:11:10scattered along a 900-mile chain.
0:11:18 > 0:11:24All these islands erupted out of the sea and were ripe for colonisation.
0:11:39 > 0:11:41The ancestors of these Solomon Islanders
0:11:41 > 0:11:46made that initial 60-mile crossing some 30,000 years ago.
0:11:57 > 0:12:02Whether their ancestors paddled across in hollowed-out tree trunks like these,
0:12:02 > 0:12:06or floated on giant bamboo rafts, no-one knows.
0:12:20 > 0:12:24And with land occasionally in sight,
0:12:24 > 0:12:28they would have surely been tempted to investigate.
0:12:40 > 0:12:44By the time people arrived, the Solomons were packed
0:12:44 > 0:12:48with almost a quarter of the plants and animals found in New Guinea...
0:12:52 > 0:12:57..including their old adversary, the saltwater crocodile.
0:13:01 > 0:13:05A 60-mile swim would be an unimaginable feat for most animals
0:13:05 > 0:13:08but salties are not most animals.
0:13:10 > 0:13:13One of the few crocodiles to tolerate saltwater,
0:13:13 > 0:13:18they are also the largest and strongest swimmers.
0:13:20 > 0:13:22Guided by an internal compass,
0:13:22 > 0:13:25they made landfall throughout the Solomons
0:13:25 > 0:13:29and became the most easterly population of crocodiles in the Pacific.
0:13:34 > 0:13:39Once arrived, they'd have had plenty to feast on.
0:13:46 > 0:13:49The waters surrounding New Guinea and the Solomons
0:13:49 > 0:13:54are the richest and most diverse in the world.
0:13:55 > 0:14:00Indeed, there are more species of fish on one of these reefs
0:14:00 > 0:14:03than in the whole of the Caribbean.
0:14:05 > 0:14:09But how did all this life reach the Solomons from New Guinea?
0:14:18 > 0:14:23You might think it would be easy for a fish to swim between these small islands.
0:14:23 > 0:14:25But not so.
0:14:25 > 0:14:29You wouldn't find these little fish in deep water.
0:14:32 > 0:14:37The open ocean beyond their shallow reef is, in fact, a huge barrier.
0:14:37 > 0:14:41So how did all these fish come to be here?
0:14:46 > 0:14:51Colonising new reefs is a challenge faced by fish across the South Pacific,
0:14:51 > 0:14:53but they have a simple solution.
0:14:55 > 0:15:00Once a year, thousands of groupers gather on the reefs.
0:15:00 > 0:15:04With the coming of the full moon, an extraordinary event unfolds.
0:15:11 > 0:15:13They spawn.
0:15:13 > 0:15:18A female darts up and releases millions of eggs, quickly followed by the males,
0:15:18 > 0:15:20who jostle to fertilise them.
0:15:28 > 0:15:32But starting new life can end in death.
0:15:34 > 0:15:36Grey reef sharks.
0:15:56 > 0:16:00Groupers are normally too quick for sharks...
0:16:02 > 0:16:05..but a distracted grouper is shark bait.
0:16:30 > 0:16:34The sharks may snatch a few adults,
0:16:34 > 0:16:40but millions upon millions of fertilised grouper eggs are picked up by the current.
0:16:46 > 0:16:50Out in the open ocean, they hatch into larvae
0:16:50 > 0:16:53and become part of the vast plankton soup.
0:17:01 > 0:17:05And it's not just fish that depend on the whim of the open ocean
0:17:05 > 0:17:07to disperse their larvae.
0:17:07 > 0:17:11Land crabs and other crustaceans do too.
0:17:15 > 0:17:17But there's a deadline.
0:17:17 > 0:17:21They each have a set number of days to reach new islands.
0:17:31 > 0:17:34Astonishingly, these larvae are able to home in
0:17:34 > 0:17:37on the smells and sounds of distant reefs.
0:17:44 > 0:17:46Out of the millions of larvae that set off,
0:17:46 > 0:17:50only a small fraction will succeed in colonising new islands.
0:18:00 > 0:18:04Curiously, some freshwater fish also spawn at sea
0:18:04 > 0:18:08and use the sea to help their larvae colonise rivers.
0:18:19 > 0:18:24These freshwater eels in the Solomons began their lives hundreds of miles away,
0:18:24 > 0:18:29possibly in a deep sea trench off New Guinea.
0:18:32 > 0:18:35Yet as larvae and then elvers,
0:18:35 > 0:18:39they made their way into these freshwater pools
0:18:39 > 0:18:44and over 40 years, grew into two-metre giants.
0:18:59 > 0:19:04The eels are highly prized by the locals.
0:19:10 > 0:19:14These Solomon Islanders hand feed them, not to fatten them up for dinner
0:19:14 > 0:19:17but to encourage them to stick around.
0:19:21 > 0:19:24By scavenging on whatever's decaying here,
0:19:24 > 0:19:27the eels clean the islanders' precious pools of drinking water...
0:19:27 > 0:19:32and over time, the honorary guests have become tame.
0:20:05 > 0:20:10One day, these adult freshwater eels will return to the sea to spawn...
0:20:10 > 0:20:13after which they'll die.
0:20:20 > 0:20:23For now, they are as good as pets.
0:20:32 > 0:20:36Away from the coast, animals are thin on the ground.
0:20:40 > 0:20:46The Solomons have only a quarter of the reptiles and birds that New Guinea has.
0:20:46 > 0:20:49For mammals like echidnas and kangaroos,
0:20:49 > 0:20:52the water proved too great a hurdle.
0:20:52 > 0:20:56But some mammals did make it here.
0:21:03 > 0:21:06When it comes to reaching new islands,
0:21:06 > 0:21:09flying must surely have been the easiest way to get there.
0:21:12 > 0:21:15But the 60 miles between New Guinea and the Solomons
0:21:15 > 0:21:21still proved a formidable challenge for many winged creatures.
0:21:23 > 0:21:25With their four-foot wingspans,
0:21:25 > 0:21:30giant fruit bats succeeded where other fliers failed.
0:21:34 > 0:21:40Carrying undigested fruit seeds from New Guinea in their stomachs,
0:21:40 > 0:21:44they inadvertently helped sow the Solomons' rainforests.
0:21:48 > 0:21:51CHATTERING SQUAWKS
0:21:56 > 0:22:01By day, these nocturnal fruit bats roost communally
0:22:01 > 0:22:04in the safety of the tallest trees.
0:22:11 > 0:22:17From the few bats that made it here, there are now 18 different species.
0:22:19 > 0:22:24They have become the most widespread native mammal in the South Pacific.
0:22:29 > 0:22:35East of the Solomons, the distance between islands increases dramatically.
0:22:35 > 0:22:40It's now 1,000 miles of open ocean before the next island groups -
0:22:40 > 0:22:45Fiji, Samoa and Tonga.
0:22:57 > 0:23:02Of all these island clusters, Fiji is the largest...
0:23:05 > 0:23:08..made up of over 300 volcanic islands,
0:23:08 > 0:23:11formed some 40 million years ago.
0:23:18 > 0:23:22Fiji is around two-thirds the size of the Solomons,
0:23:22 > 0:23:26so remained a reasonable target for would-be colonisers.
0:23:30 > 0:23:33Despite its isolation, it is still home
0:23:33 > 0:23:36to nearly half the number of plant species found in the Solomons.
0:23:38 > 0:23:42But animal colonisers were not so successful.
0:23:47 > 0:23:51At night, the forests are eerily quiet.
0:23:54 > 0:23:57Only a handful of bats made it here,
0:23:57 > 0:24:03the only mammals to do so, and there are far fewer birds.
0:24:16 > 0:24:20In the absence of ground predators,
0:24:20 > 0:24:23invertebrates evolved into monsters.
0:24:36 > 0:24:41This millipede is one of the biggest of its kind,
0:24:41 > 0:24:44running almost a foot long.
0:24:45 > 0:24:50Its diet of rotten vegetation may have sustained its ancestors
0:24:50 > 0:24:54on their long journeys to these distant shores.
0:24:54 > 0:24:57But how did they get here?
0:25:01 > 0:25:04FROG CROAKS
0:25:09 > 0:25:14Perhaps more surprising, two species of frog also made it to Fiji.
0:25:16 > 0:25:21Surprising because adult frogs quickly die in saltwater.
0:25:30 > 0:25:34But the ancestor of this frog may have arrived here as a tadpole.
0:25:38 > 0:25:43Tadpoles normally need pools of freshwater to develop in,
0:25:43 > 0:25:47but these actually mature inside the egg.
0:25:51 > 0:25:53So, on long journeys,
0:25:53 > 0:25:57these eggs would have been like little survival capsules.
0:25:59 > 0:26:03But the question remains - how did they ever reach these islands?
0:26:12 > 0:26:18Maybe the same way as Fiji's most intriguing castaway of all.
0:26:25 > 0:26:28Discovered only 30 years ago,
0:26:28 > 0:26:31Fiji's largest surviving reptile was marooned
0:26:31 > 0:26:34on a handful of its outer islands.
0:26:41 > 0:26:43Crested iguanas.
0:26:43 > 0:26:48They're one of the toughest and most saltwater-tolerant lizards around.
0:26:50 > 0:26:55In the breeding season, males, nearly a metre long,
0:26:55 > 0:26:57battle it out for a mate.
0:26:59 > 0:27:04They begin with a gentle bout of competitive head-bobbing.
0:27:07 > 0:27:11If no-one backs down, things become more animated.
0:27:11 > 0:27:12IGUANA HISSES
0:27:20 > 0:27:24The loser scrambles for cover.
0:27:24 > 0:27:26IGUANA HISSES
0:27:30 > 0:27:34So where did these large lizards come from?
0:27:34 > 0:27:38Some speculate Asia, 4,000 miles to the west...
0:27:38 > 0:27:41others, the Americas, 5,000 miles to the east.
0:27:41 > 0:27:46But how did they end up here in Fiji?
0:27:48 > 0:27:52One answer is that the iguanas, the frogs and the millipedes
0:27:52 > 0:27:55were all carried here by powerful oceanic forces.
0:28:09 > 0:28:13Every day, large waves beat down on tiny islands across the Pacific.
0:28:24 > 0:28:29Imposing as they may be, these have little impact on island life.
0:28:39 > 0:28:43But every year, much larger waves rise out of the ocean.
0:28:50 > 0:28:54They're generated by underwater landslides and earthquakes.
0:28:56 > 0:28:59Known as tsunamis, they can flatten coastlines.
0:29:10 > 0:29:16Yet these destructive forces may have also brought life to some islands.
0:29:21 > 0:29:26As tsunamis strike the coast, rafts of vegetation can be cast adrift.
0:29:29 > 0:29:33Perhaps animals were caught up in those rafts too.
0:29:40 > 0:29:45Could this have been the answer to how these animals made it to Fiji?
0:29:46 > 0:29:49After all, they are the hardiest of their kind
0:29:49 > 0:29:52and could have survived long sea journeys.
0:29:58 > 0:30:03Fiji's first animals washed up tens of millions of years ago.
0:30:07 > 0:30:10But humans were slow off the block.
0:30:10 > 0:30:14They only arrived here 3,500 years ago.
0:30:21 > 0:30:24Their history remains thin on the ground.
0:30:26 > 0:30:32The ruins of Nan Madol are one of only two ancient cities ever found in the Pacific.
0:30:35 > 0:30:38With archaeological evidence so scarce,
0:30:38 > 0:30:43the origins of people in the central Pacific were hotly debated.
0:30:46 > 0:30:49Were they Papuans from New Guinea,
0:30:49 > 0:30:55native Indians from the Americas, or another race of people from Asia?
0:31:00 > 0:31:06Only very recently has their language been traced back to Taiwan...
0:31:07 > 0:31:10..and their pottery to the Philippines.
0:31:10 > 0:31:14Combined with DNA analysis, evidence now points to the Lapita,
0:31:14 > 0:31:17a seafaring people from Southeast Asia.
0:31:21 > 0:31:23THEY SING
0:31:33 > 0:31:37Back in the Solomons, on the tiny island of Taumako,
0:31:37 > 0:31:41descendants of the Lapita still build traditional voyaging canoes.
0:31:57 > 0:32:00These canoes may look basic,
0:32:00 > 0:32:04but their relative sophistication enabled the Lapita
0:32:04 > 0:32:08to travel further into the Pacific than anyone had ever dared before.
0:32:11 > 0:32:16They were no longer reliant on paddles alone - they had wind power.
0:32:17 > 0:32:21Sails, perhaps similar to this crab-claw design,
0:32:21 > 0:32:24enabled the Lapita to cover huge distances.
0:32:48 > 0:32:53But with heavy sails, the canoes needed extra stability.
0:32:54 > 0:32:58The Lapita added a second hull
0:32:58 > 0:33:02and the long-distance outrigger canoe was finally born.
0:33:15 > 0:33:22The Lapita's first voyages into the unknown must have appeared suicidal.
0:33:26 > 0:33:31Although many were lost at sea, some Lapita DID reach new islands,
0:33:31 > 0:33:35thanks to their extraordinary navigation skills.
0:33:35 > 0:33:40This man can interpret the direction of land
0:33:40 > 0:33:43by reading wave and swell patterns.
0:33:49 > 0:33:53Like his ancestors, he carries in his head a complex wind map
0:33:53 > 0:33:58detailing the various seasonal winds that serve as a compass.
0:34:01 > 0:34:05And at night, he can navigate by the stars.
0:34:14 > 0:34:18In craft like these, the Lapita reached the islands of Tonga,
0:34:18 > 0:34:232,000 miles east of New Guinea, in the heart of the South Pacific.
0:34:33 > 0:34:38Further east, the odds of a castaway making land drop steeply
0:34:38 > 0:34:42as the islands become fewer and even more isolated.
0:34:50 > 0:34:56Almost all animal castaways died of exposure, hunger or thirst
0:34:56 > 0:35:00long before reaching French Polynesia in the eastern Pacific.
0:35:02 > 0:35:06Reaching land here was a matter of extraordinary luck.
0:35:09 > 0:35:13Unlike Fiji, there are no bats in French Polynesia,
0:35:13 > 0:35:16no frogs and only a handful of lizards.
0:35:19 > 0:35:22The most successful travellers were the long-haul fliers -
0:35:22 > 0:35:25sooty terns.
0:35:25 > 0:35:30Incredibly, they can stay in the air for four years without landing...
0:35:37 > 0:35:41..but to breed, they must return to nesting sites on remote islands.
0:35:41 > 0:35:45And when they do, they introduce new life.
0:35:49 > 0:35:55Sticky or barbed seeds fasten on to their feathers and hitch rides across oceans.
0:36:02 > 0:36:08On some islands, 75% of plants arrived with the birds.
0:36:08 > 0:36:10HIGH-PITCHED CRIES
0:36:14 > 0:36:17Seeds are even carried in the stomachs of some birds.
0:36:20 > 0:36:23As if getting a lift wasn't enough for these seeds,
0:36:23 > 0:36:25seabirds also provide them with something else.
0:36:26 > 0:36:29The seafood these birds bring back to the islands
0:36:29 > 0:36:35is turned into nutrient-rich guano - plant fertiliser.
0:36:39 > 0:36:44There's enough to transform barren coral atolls into fertile groves.
0:36:52 > 0:36:56There is one plant castaway that needs no help in finding new land -
0:36:56 > 0:36:59a plant that has probably done more
0:36:59 > 0:37:03to change the fortunes of island life than any other,
0:37:03 > 0:37:07and one of the greatest long-distance travellers of all time.
0:37:13 > 0:37:15The humble coconut.
0:37:22 > 0:37:26Its seed is a compact survival capsule.
0:37:29 > 0:37:32Buoyant and filled with food for germination,
0:37:32 > 0:37:35it can survive for up to two months at sea...
0:37:37 > 0:37:42...long enough to float from one remote island to the next.
0:38:00 > 0:38:03On arrival, it lays down roots into bare sand
0:38:03 > 0:38:07and taps into the reservoirs of underground freshwater.
0:38:13 > 0:38:19Without coconuts, most of the tropical islands in the South Pacific
0:38:19 > 0:38:23would have remained uninhabitable for both animals and people.
0:38:32 > 0:38:36There is one set of islands, however, that is so remote
0:38:36 > 0:38:39that even the coconut couldn't reach it.
0:38:45 > 0:38:51North of the equator, 2,500 miles from the nearest landmass of North America,
0:38:51 > 0:38:57lies the most isolated chain of islands in the world - Hawaii.
0:39:20 > 0:39:23The longest archipelago in the Pacific,
0:39:23 > 0:39:27Hawaii consists of over 100 ancient volcanic islands,
0:39:27 > 0:39:30stretching for 2,000 miles.
0:39:35 > 0:39:41Yet it is so remote that less than 500 kinds of animal settled here
0:39:41 > 0:39:43in 30 million years.
0:39:54 > 0:39:59But for those who did make it to this lush and fertile land,
0:39:59 > 0:40:02the world was their oyster.
0:40:05 > 0:40:09Here, coconut palms have been replaced by giant tree ferns
0:40:09 > 0:40:11standing over seven metres tall.
0:40:19 > 0:40:23From the 13 kinds of spider that made it here,
0:40:23 > 0:40:26over a 100 new species evolved - like the happy-face spider.
0:40:28 > 0:40:34From just one species of fruit fly came over 1,000 others.
0:40:37 > 0:40:41And here, caterpillars were free to become carnivores.
0:40:41 > 0:40:43CATERPILLAR CRUNCHES
0:40:43 > 0:40:47Hawaii's 20 surviving species of honey creeper
0:40:47 > 0:40:50also evolved from just a few individuals.
0:40:51 > 0:40:56Compared to seabirds, honey creepers are poor fliers.
0:40:56 > 0:40:59So how did the ancestors of these forest birds
0:40:59 > 0:41:03and Hawaii's other castaways get here?
0:41:08 > 0:41:10The answer may be blowing in the wind.
0:41:16 > 0:41:20Even the gentlest breeze can have a huge impact.
0:41:20 > 0:41:26Tree ferns stir and release their lightweight spores.
0:41:31 > 0:41:36Thermal updrafts can carry the spores 30,000 feet into the jet stream.
0:41:41 > 0:41:46And there are even animals designed to ride these high-altitude air currents.
0:41:48 > 0:41:53Near-weightless spiderlings are expert ballooners,
0:41:53 > 0:41:56catching the wind with their gossamer threads.
0:42:03 > 0:42:07Like spores, they, too, can hitch a ride on the jet stream.
0:42:10 > 0:42:14Enduring temperatures of minus 30 degrees centigrade,
0:42:14 > 0:42:19a spider can cross the breadth of the Pacific in a matter of days.
0:42:25 > 0:42:29Larger insects and animals need more than a breeze to carry them away.
0:42:39 > 0:42:45Vast tracts of warm water are a perfect environment for cyclones.
0:42:48 > 0:42:51Over half the cyclones on the planet - around 30 a year -
0:42:51 > 0:42:54form in the Pacific Ocean.
0:42:54 > 0:42:56THUNDER RUMBLES
0:43:03 > 0:43:06Heated by the warm tropical sun,
0:43:06 > 0:43:09water evaporates and forms massive thunderstorms,
0:43:09 > 0:43:11fuelling a whirling vortex...
0:43:15 > 0:43:19..in some cases up to 500 miles wide.
0:43:25 > 0:43:30When they collide with islands, they unleash their fury.
0:43:42 > 0:43:46Winds in excess of 100mph can uproot a forest.
0:44:04 > 0:44:06Large insects can be sucked up into the sky...
0:44:10 > 0:44:13..so why not birds, bats and lizards?
0:44:26 > 0:44:29In fact, all these creatures are known to have been carried
0:44:29 > 0:44:33hundreds of miles out to sea by cyclones.
0:44:40 > 0:44:45When the storm subsides, most will meet a watery grave.
0:44:55 > 0:44:59But a very, very lucky few will land on firm ground
0:44:59 > 0:45:04and from these survivors, a whole island dynasty may be born.
0:45:09 > 0:45:15No matter how remote the Hawaiian islands are, or how hostile,
0:45:15 > 0:45:18there is one creature that has reached almost all of them.
0:45:20 > 0:45:23LAVA HISSES
0:45:23 > 0:45:28LAVA HISSES AND CRACKLES
0:45:30 > 0:45:33The mourning gecko.
0:45:37 > 0:45:39It is the ultimate castaway...
0:45:41 > 0:45:45..the marathon winner on the long journey from New Guinea.
0:45:54 > 0:45:59Incredibly, the female has done away with the need for a mate.
0:46:09 > 0:46:14Instead, she simply produces eggs that need no fertilisation.
0:46:18 > 0:46:25So one single female washed up on an island could start a whole population.
0:46:31 > 0:46:33Along with this extraordinary ability,
0:46:33 > 0:46:36these thick-skinned and salt-resistant geckos
0:46:36 > 0:46:40could also survive long sea passages on rafts,
0:46:40 > 0:46:43and even the force of cyclones.
0:46:50 > 0:46:53But there is more to the gecko's story than this.
0:47:01 > 0:47:03Less than 2,000 years ago,
0:47:03 > 0:47:06something happened that was to revolutionise
0:47:06 > 0:47:09the spread of plants and animals.
0:47:17 > 0:47:21Taking to their sailing boats once more, descendants of the Lapita
0:47:21 > 0:47:26left the central Pacific and set off again in search of new lands...
0:47:28 > 0:47:31..into the great unknown.
0:47:35 > 0:47:39As pioneers, they took everything they would need to start their lives afresh.
0:47:39 > 0:47:40Livestock.
0:47:40 > 0:47:43Plants for cultivation.
0:47:48 > 0:47:50Even the coconut.
0:47:57 > 0:48:01But they would also have taken a long list of stowaways...
0:48:05 > 0:48:08..like the mourning gecko.
0:48:11 > 0:48:13This lizard was just one castaway
0:48:13 > 0:48:19which no longer had to rely on its stamina and luck to reach new lands.
0:48:21 > 0:48:23It could now hitch a free ride.
0:48:31 > 0:48:36In a series of epic voyages, the descendants of the Lapita,
0:48:36 > 0:48:38the people we now call the Polynesians,
0:48:38 > 0:48:42succeeded in colonising the far corners of the South Pacific -
0:48:42 > 0:48:46from Hawaii to New Zealand, even to Easter Island,
0:48:46 > 0:48:51nearly 7,000 miles east of New Guinea.
0:48:53 > 0:49:00In doing so, animal castaways now reached new islands at a rate never seen before,
0:49:00 > 0:49:04changing the nature of the South Pacific for ever.
0:49:23 > 0:49:27For years, the Solomon Islands have been home
0:49:27 > 0:49:31to legends of massive saltwater crocodiles.
0:49:32 > 0:49:37Separating fact from fiction, the goal of the Castaways team
0:49:37 > 0:49:42was to capture evidence that huge crocs WERE living on these little-known islands.
0:49:49 > 0:49:53Braving the high seas, cameraman Wade Fairley
0:49:53 > 0:49:56made the 1,000-mile crossing from Australia to the Solomons.
0:50:00 > 0:50:04The Solomons are a chain of almost 1,000 remote islands.
0:50:04 > 0:50:06Wade would need the freedom of a boat
0:50:06 > 0:50:10to stand a chance of finding these mysterious crocodiles.
0:50:10 > 0:50:11Caught some dinner.
0:50:11 > 0:50:13Joined by producer Mark Brownlow,
0:50:13 > 0:50:18they started their two-week expedition in the Western Provinces.
0:50:21 > 0:50:23CHILDREN GIGGLE
0:50:23 > 0:50:27With few scientific leads, they would have to rely on local knowledge.
0:50:29 > 0:50:30HE SPEAKS PIDGIN
0:50:30 > 0:50:35The crocodile tales began, interpreted by Wade, a fluent pidgin-speaker.
0:50:39 > 0:50:41WADE: Oh, yeah?
0:50:41 > 0:50:43MAN: Sacred crocodile.
0:50:43 > 0:50:46- And he's got no tail? - No, no tail.
0:50:52 > 0:50:56Following the tip-off of the four-metre tail-less crocodile,
0:50:56 > 0:50:59they decided to track him down that night,
0:50:59 > 0:51:01when these reptiles are most active.
0:51:04 > 0:51:07To minimise disturbance,
0:51:07 > 0:51:11they scanned the mangroves with infrared light, invisible to crocodiles.
0:51:14 > 0:51:16Well, that's remarkable.
0:51:16 > 0:51:18I would have guaranteed that we were onto something here,
0:51:18 > 0:51:20but we haven't seen one crocodile.
0:51:22 > 0:51:24WATER SPLASHES Ooh.
0:51:26 > 0:51:28Aside from a mysterious splash,
0:51:28 > 0:51:32the only confirmed sightings were juveniles.
0:51:34 > 0:51:36Where were the adults?
0:51:39 > 0:51:40Over the next two nights,
0:51:40 > 0:51:44the tail-less croc continued to elude them.
0:51:47 > 0:51:50It was time to move on.
0:51:51 > 0:51:5370 miles to the east,
0:51:53 > 0:51:56they reached the island of Liapari, in the central Solomons.
0:51:58 > 0:52:01We're hoping to film some crocs in a freshwater lake,
0:52:01 > 0:52:04which we...we hear is "stacka".
0:52:04 > 0:52:05The big question is,
0:52:05 > 0:52:09is there going to be stacka too much crocodiles or stacka little bit?
0:52:09 > 0:52:15Once more, they were regaled by stories of giant crocodiles.
0:52:15 > 0:52:20You say the old man, he talk to the crocodiles?
0:52:25 > 0:52:27I try to explain it.
0:52:27 > 0:52:30He knows the crocodiles, he's got some, you know, magic...
0:52:30 > 0:52:32- Magic. - ...That they can work together.
0:52:32 > 0:52:35But there were words of warning.
0:52:48 > 0:52:51Unnerved by tales of man-eating crocs,
0:52:51 > 0:52:56Mark and Wade headed off in search of the crocodile lake.
0:52:57 > 0:53:00On the way, they passed some sinister sights.
0:53:03 > 0:53:05A skull shrine -
0:53:05 > 0:53:08evidence of the island's head-hunting past.
0:53:10 > 0:53:13SPEAKS IN PIDGIN
0:53:13 > 0:53:17- So this sacred place with the skulls...- Yeah, yeah.
0:53:17 > 0:53:20..Is guarded by the crocodiles of the lake?
0:53:23 > 0:53:30Reaching the lake, Wade and Mark edged as close as they dared.
0:53:30 > 0:53:32Would they see any of these legendary crocs?
0:53:32 > 0:53:35(We've got no idea how big these saltwater crocs are,
0:53:35 > 0:53:39(but we don't dare get any closer - it could be too dangerous.)
0:53:40 > 0:53:46That afternoon, Wade got his first shot of a modestly sized, two-metre crocodile.
0:53:48 > 0:53:52Despite camping out for three days, they failed to spot anything larger.
0:53:52 > 0:53:56Whatever big crocs were out there did not materialise.
0:54:01 > 0:54:03It was beginning to feel like a wild croc chase,
0:54:03 > 0:54:07but they decided to push on to new islands.
0:54:12 > 0:54:17A hundred miles east, they dropped anchor in Marovo Lagoon.
0:54:17 > 0:54:23Wade explored the maze of mangroves - prime crocodile country.
0:54:23 > 0:54:26INDISTINCT SPEECH
0:54:26 > 0:54:28That was rather sobering advice.
0:54:28 > 0:54:31I was paddling quite close to the bank -
0:54:31 > 0:54:33he told me to come back out into the middle
0:54:33 > 0:54:35because that's where the crocodiles are.
0:54:41 > 0:54:47They called in at the local village to ask their advice on where to stake out,
0:54:47 > 0:54:52discovering worrying signs of big crocodiles at large.
0:54:52 > 0:54:54SPEAKS IN PIDGIN
0:55:08 > 0:55:13Only a large crocodile would be capable of inflicting such a horrific injury.
0:55:13 > 0:55:17The village chief confirmed that attacks
0:55:17 > 0:55:21on both the villagers and their livestock were on the increase.
0:55:41 > 0:55:45With displaced crocodiles now encroaching on villages,
0:55:45 > 0:55:47there appeared to be a growing conflict.
0:55:47 > 0:55:48CHILDREN SING
0:55:59 > 0:56:01WADE: Do you think he's a danger?
0:56:07 > 0:56:10# ..Thank you for your love... #
0:56:17 > 0:56:20To learn more about these problem crocodiles,
0:56:20 > 0:56:24the team headed to the Solomons' capital, Honiara -
0:56:24 > 0:56:27headquarters for the international peacekeeping force
0:56:27 > 0:56:31policing both the islanders and their crocodiles.
0:56:31 > 0:56:35We've had some tragedies here where people have lost their life or been injured.
0:56:35 > 0:56:38Not nice at all, and that worries us,
0:56:38 > 0:56:41but I think we have a system to manage that
0:56:41 > 0:56:45inasmuch that we've got this team of people that are skilled
0:56:45 > 0:56:48and well trained to go and destroy them.
0:56:48 > 0:56:53Not that we really want to do that, but when it's asked for, we'll go and do it.
0:56:55 > 0:56:59So the large crocodiles have good reason to be camera-shy.
0:56:59 > 0:57:03Hunted down, only the wiliest crocs survive.
0:57:06 > 0:57:10It seemed that the team's best chance was away from people.
0:57:10 > 0:57:12The peacekeepers had recommended
0:57:12 > 0:57:16the wild and mostly uninhabited coast of Guadalcanal.
0:57:16 > 0:57:21On the tip-off of a large crocodile seen laying up on this lonely stretch of beach,
0:57:21 > 0:57:29Wade set up his camera hide one last time and the long wait began.
0:57:35 > 0:57:40It's almost dawn. It's been a long, long, long, long night. Absolutely nothing.
0:57:40 > 0:57:44All I've seen is a dog and some crabs.
0:57:44 > 0:57:47I can only figure that the crocodile knows I'm here.
0:57:47 > 0:57:51He's a big, old, smart bugger, for sure, and if he's grown that big,
0:57:51 > 0:57:55it's obviously from being smart, and he's outsmarted me.
0:57:59 > 0:58:02Yet it was at dawn, after a three-day vigil,
0:58:02 > 0:58:06that an impressive, three-metre crocodile finally appeared.
0:58:09 > 0:58:12In the end, Wade only managed to record
0:58:12 > 0:58:16a few minutes of footage of these camera-shy giants.
0:58:16 > 0:58:19But these images were proof of the existence
0:58:19 > 0:58:22of large saltwater crocodiles in the Solomons -
0:58:22 > 0:58:26the last living legends in the South Pacific.
0:58:47 > 0:58:51Subtitles by Red Bee Media Ltd 2009
0:58:51 > 0:58:54E-mail subtitling@bbc.co.uk