1 00:00:09,360 --> 00:00:11,520 Far away, cut off by vast oceans... 2 00:00:16,880 --> 00:00:20,120 ..lie Earth's tropical islands. 3 00:00:25,080 --> 00:00:27,880 Home to remarkable animal castaways... 4 00:00:30,280 --> 00:00:32,520 ..that have evolved in isolation. 5 00:00:37,000 --> 00:00:40,040 And human cultures that have adapted in extraordinary ways. 6 00:00:44,560 --> 00:00:49,880 From the jungles of Borneo with their staggering wild diversity... 7 00:00:57,120 --> 00:01:00,840 ..to Hawaii, the most remote island chain, 8 00:01:00,840 --> 00:01:04,320 colonised by only the hardiest pioneers. 9 00:01:08,640 --> 00:01:11,840 And Madagascar, the oldest island of all... 10 00:01:13,360 --> 00:01:17,720 ..where time has given rise to thousands of unique species. 11 00:01:26,640 --> 00:01:29,400 These tropical islands 12 00:01:29,400 --> 00:01:32,920 have developed into astonishing and unique worlds. 13 00:01:35,960 --> 00:01:41,680 Cradling precious life found nowhere else on Earth. 14 00:02:04,160 --> 00:02:07,200 In the tropical waters of the Indian Ocean... 15 00:02:08,640 --> 00:02:12,280 ..lies the oldest island on Earth. 16 00:02:16,960 --> 00:02:18,440 Madagascar. 17 00:02:21,000 --> 00:02:24,040 Isolated for longer than any other island. 18 00:02:26,120 --> 00:02:31,280 Life has had time to evolve in the most surprising ways. 19 00:02:36,640 --> 00:02:41,120 With over 15,000 species found nowhere else. 20 00:02:44,600 --> 00:02:48,040 Madagascar boasts more unique plants and animals 21 00:02:48,040 --> 00:02:51,760 than any other island on the planet. 22 00:02:56,040 --> 00:02:59,360 Madagascar was formed nearly 90 million years ago. 23 00:03:01,640 --> 00:03:05,880 Giant landmass, known as Gondwana, broke apart. 24 00:03:08,080 --> 00:03:11,080 As India split from Africa, 25 00:03:11,080 --> 00:03:14,200 Madagascar was cast adrift. 26 00:03:25,400 --> 00:03:29,800 It's a vast island almost the size of France. 27 00:03:31,800 --> 00:03:36,240 And home to an astonishing array of ancient habitats. 28 00:03:41,600 --> 00:03:45,520 At its heart lie the highlands, 29 00:03:45,520 --> 00:03:50,320 an immense mountainous spine that determines the island's climate. 30 00:03:53,240 --> 00:03:57,520 Warm, wet air blows in off the Indian Ocean, 31 00:03:57,520 --> 00:03:59,880 drenching the east of Madagascar with rain. 32 00:04:02,800 --> 00:04:07,200 But the mountains block this rain from reaching the west, 33 00:04:07,200 --> 00:04:10,480 creating a great expanse of desert. 34 00:04:18,560 --> 00:04:23,120 This arid landscape stretches halfway up the west coast. 35 00:04:28,200 --> 00:04:32,960 It was here, around 55 million years ago, 36 00:04:32,960 --> 00:04:36,880 that a few animal castaways washed ashore. 37 00:04:40,440 --> 00:04:46,200 Having somehow survived the 300-mile crossing from Africa. 38 00:04:52,320 --> 00:04:55,360 One of the very first mammals to arrive 39 00:04:55,360 --> 00:04:57,840 was an ancient species of primate. 40 00:05:01,080 --> 00:05:06,040 And their direct descendants still live here in the desert today. 41 00:05:15,520 --> 00:05:17,920 Ring-tailed lemurs. 42 00:05:25,640 --> 00:05:27,960 It's dawn. 43 00:05:27,960 --> 00:05:33,240 And a family of nine soak up the warmth of the early morning sun, 44 00:05:33,240 --> 00:05:36,600 preserving vital energy for the day ahead. 45 00:05:48,240 --> 00:05:53,280 This young lemur is just six months old... 46 00:05:57,560 --> 00:06:02,480 ..and born into the harshest habitat on the island. 47 00:06:10,880 --> 00:06:14,360 Known as the Spiny Forest. 48 00:06:32,920 --> 00:06:37,360 Tiny leathery leaves provide little nourishment. 49 00:06:47,320 --> 00:06:50,760 The troop spends up to eight hours a day 50 00:06:50,760 --> 00:06:53,200 scouring the desert for food. 51 00:06:54,200 --> 00:06:57,520 Tackling even the most hostile vegetation. 52 00:07:08,440 --> 00:07:13,320 The sticky sap that oozes out of Euphorbia plants 53 00:07:13,320 --> 00:07:17,600 can be caustic, and burn human flesh. 54 00:07:27,360 --> 00:07:31,960 Yet ringtails are resistant to their corrosive powers. 55 00:07:41,520 --> 00:07:46,000 Euphorbia sap is also rich in fats. 56 00:07:47,520 --> 00:07:52,240 Much-needed fuel that will help this young lemur survive 57 00:07:52,240 --> 00:07:54,280 this inhospitable desert. 58 00:08:18,520 --> 00:08:22,640 Ringtails are just one of the many species of lemur. 59 00:08:25,520 --> 00:08:29,760 These primates are found only on Madagascar. 60 00:08:36,400 --> 00:08:41,480 Their ancient ancestors gradually spread east across the island. 61 00:08:47,080 --> 00:08:51,400 Adapting to each of Madagascar's varied habitats. 62 00:09:05,480 --> 00:09:09,520 They now number more than 100 different species. 63 00:09:38,080 --> 00:09:41,360 Humans are thought to have arrived on this island 64 00:09:41,360 --> 00:09:43,600 just a few thousand years ago. 65 00:09:51,600 --> 00:09:55,520 First from Asia, and then from Africa, 66 00:09:55,520 --> 00:09:57,200 they settled on the coast. 67 00:10:06,200 --> 00:10:11,760 Pushing inland, those in the west faced the hostile desert. 68 00:10:15,080 --> 00:10:20,960 Just 20 miles from the coastline lies the village of Ampotaka. 69 00:10:24,040 --> 00:10:26,080 It's the dry season. 70 00:10:26,080 --> 00:10:28,960 Temperatures often reach 40 degrees Celsius. 71 00:10:32,360 --> 00:10:35,640 It hasn't rained for ten months now. 72 00:10:41,760 --> 00:10:45,680 With their nearest water supply over 40 miles away, 73 00:10:45,680 --> 00:10:49,240 life is a daily struggle. 74 00:10:49,240 --> 00:10:52,320 The remains of this year's melon harvest 75 00:10:52,320 --> 00:10:55,560 provide just enough water to cook with. 76 00:11:00,680 --> 00:11:06,520 At 62, Adolphe has lived through the driest of years. 77 00:11:08,520 --> 00:11:10,120 IN OWN LANGUAGE: 78 00:11:20,840 --> 00:11:26,360 Today, Adolphe is joined by his son Leris... 79 00:11:27,840 --> 00:11:31,240 ..to visit the secret to their survival. 80 00:11:38,200 --> 00:11:40,400 The baobab. 81 00:11:40,400 --> 00:11:44,080 Known as "The Tree Of Life." 82 00:11:49,120 --> 00:11:52,200 They can live for over 1,000 years. 83 00:11:54,400 --> 00:11:58,200 Growing up to 30 metres high, 84 00:11:58,200 --> 00:12:03,600 baobabs can hold vast quantities of water in their immense trunks... 85 00:12:06,240 --> 00:12:11,160 ..and can survive for years without a single drop of rain. 86 00:12:18,840 --> 00:12:23,760 For Adolphe, this baobab provides a lifeline. 87 00:12:55,200 --> 00:12:59,640 By hollowing out the soft trunk, they created a tank, 88 00:12:59,640 --> 00:13:03,320 which they could fill with water during the brief rainy season. 89 00:13:11,240 --> 00:13:16,280 This living reservoir can store thousands of litres of water. 90 00:13:18,080 --> 00:13:23,160 But this dry season has lasted so long that the tree is already empty. 91 00:13:29,240 --> 00:13:33,800 Still, it's an important opportunity to trim back the growing bark, 92 00:13:33,800 --> 00:13:36,640 maintaining the tank's size ready for the rain 93 00:13:36,640 --> 00:13:38,640 they hope will come soon. 94 00:13:44,080 --> 00:13:46,520 This tank may have run dry. 95 00:13:48,720 --> 00:13:52,680 But Adolphe inherited seven of these wells from his father. 96 00:14:01,600 --> 00:14:05,000 Only one still holds any water. 97 00:14:23,560 --> 00:14:27,800 With only enough water to last a few more weeks, 98 00:14:27,800 --> 00:14:31,280 it's a worrying time for Adolphe and his family. 99 00:14:34,040 --> 00:14:38,760 Survival in this desert depends on the arrival of the rains. 100 00:14:42,840 --> 00:14:47,520 On the forest floor, there are signs that the weather is changing. 101 00:14:56,880 --> 00:15:03,120 Tiny Labord's chameleons, only three centimetres long, begin to hatch. 102 00:15:17,520 --> 00:15:20,600 They live for only four months. 103 00:15:22,040 --> 00:15:26,040 The shortest lifespan of any land vertebrate. 104 00:15:30,960 --> 00:15:33,440 For this young male, 105 00:15:33,440 --> 00:15:35,920 it's a race against time. 106 00:15:49,000 --> 00:15:52,600 In the dry season, there is little food. 107 00:15:55,120 --> 00:15:57,880 But his hatching is perfectly timed. 108 00:15:57,880 --> 00:15:59,200 DISTANT RUMBLING 109 00:16:05,720 --> 00:16:08,040 THUNDER RUMBLING 110 00:16:10,440 --> 00:16:13,840 It's the start of the rainy season. 111 00:16:30,280 --> 00:16:34,120 The parched landscape is transformed 112 00:16:34,120 --> 00:16:36,360 into a flush of green. 113 00:16:39,560 --> 00:16:42,480 Just what this growing chameleon needs. 114 00:16:53,400 --> 00:16:55,960 As his eyes can move independently... 115 00:16:57,560 --> 00:17:00,560 ..he can spot a meal in any direction... 116 00:17:01,800 --> 00:17:07,080 ..and, by locking both eyes onto a target, judge distance. 117 00:17:11,200 --> 00:17:13,200 With deadly accuracy. 118 00:17:34,840 --> 00:17:37,320 With so much food on offer, 119 00:17:37,320 --> 00:17:41,800 the male Labord's chameleon can grow five times his size 120 00:17:41,800 --> 00:17:43,640 in just two months. 121 00:17:46,280 --> 00:17:51,080 Transforming into an adult male with an eye-catching horn. 122 00:18:01,720 --> 00:18:04,000 A female approaches. 123 00:18:09,720 --> 00:18:12,240 But the male has a rival. 124 00:18:15,440 --> 00:18:17,560 With such short lives, 125 00:18:17,560 --> 00:18:20,200 there's fierce competition for a chance to mate. 126 00:18:23,880 --> 00:18:25,480 HISSING 127 00:18:50,400 --> 00:18:53,120 With his rival out of the way, 128 00:18:53,120 --> 00:18:56,360 he hasn't got long to take this opportunity. 129 00:19:26,840 --> 00:19:29,360 After just four months, 130 00:19:29,360 --> 00:19:33,400 this male has succeeded in securing the next generation. 131 00:19:35,160 --> 00:19:41,440 The female will lay her fertilised eggs underground before she dies. 132 00:19:47,800 --> 00:19:50,800 And as the dry season returns, 133 00:19:50,800 --> 00:19:53,840 not a single adult Labord's chameleon... 134 00:19:55,040 --> 00:19:57,040 ..will be left alive. 135 00:20:10,120 --> 00:20:14,120 Arid regions cover more than half of western Madagascar. 136 00:20:16,600 --> 00:20:19,920 Including one of its most extreme habitats. 137 00:20:25,400 --> 00:20:27,320 The Grand Tsingy. 138 00:20:35,280 --> 00:20:40,960 More than 500 square miles of sharp limestone pinnacles. 139 00:20:44,480 --> 00:20:48,720 Eroded by rainfall over millions of years. 140 00:20:57,280 --> 00:21:01,520 Its deep, shaded ravines retain moisture. 141 00:21:03,000 --> 00:21:05,800 Allowing small pockets of forest to grow. 142 00:21:09,360 --> 00:21:12,160 And providing an oasis... 143 00:21:13,280 --> 00:21:15,480 ..for an extraordinary lemur. 144 00:21:26,840 --> 00:21:28,480 Decken's sifaka. 145 00:21:42,680 --> 00:21:45,560 This youngster is three months old... 146 00:21:47,800 --> 00:21:51,720 ..and already practising the vital skill of leaping. 147 00:22:00,440 --> 00:22:03,440 No one cluster of trees is large enough 148 00:22:03,440 --> 00:22:07,400 to sustain a whole family of hungry sifakas. 149 00:22:07,400 --> 00:22:13,560 This mother and son need to seek out another pocket of vegetation. 150 00:22:13,560 --> 00:22:16,000 Possibly hundreds of metres away. 151 00:22:17,960 --> 00:22:21,320 They must run a deadly gauntlet. 152 00:22:28,000 --> 00:22:33,480 These limestone shards stand more than 100 metres tall... 153 00:22:36,640 --> 00:22:40,160 ..and are sharp enough to shred human skin. 154 00:22:58,960 --> 00:23:03,240 But sifakas have thick, rubbery footpads, 155 00:23:03,240 --> 00:23:08,600 and spring-like legs that can leap nine metres in a single bound. 156 00:23:10,880 --> 00:23:16,320 These lemurs have evolved into blade runners. 157 00:23:59,640 --> 00:24:05,120 Safely across, mother and son claim their reward. 158 00:24:05,120 --> 00:24:09,160 The fresh, juicy leaves they need to survive. 159 00:24:22,960 --> 00:24:26,440 Over millions of years of evolution, 160 00:24:26,440 --> 00:24:30,280 the Decken's sifaka has overcome the extreme conditions 161 00:24:30,280 --> 00:24:31,760 of the Grand Tsingy. 162 00:24:35,160 --> 00:24:40,880 But as Madagascar's lemurs continued to spread east across the island, 163 00:24:40,880 --> 00:24:44,880 they eventually encountered an immense barrier. 164 00:24:47,400 --> 00:24:51,800 Over 100 miles inland, the Highlands. 165 00:25:06,440 --> 00:25:12,520 It's these towering peaks that divide Madagascar's climate. 166 00:25:12,520 --> 00:25:17,080 Rising over 2,000 metres, they capture the full force 167 00:25:17,080 --> 00:25:20,200 of the seasonal rain blowing in from the east. 168 00:25:30,000 --> 00:25:35,320 Millions of years of rainfall have carved out fertile valleys, 169 00:25:35,320 --> 00:25:37,120 perfect for growing rice. 170 00:25:38,560 --> 00:25:40,920 A staple food of Madagascar's people. 171 00:25:44,360 --> 00:25:47,240 Just a few thousand years ago, 172 00:25:47,240 --> 00:25:50,280 settlers from Asia brought the skills to turn even 173 00:25:50,280 --> 00:25:54,320 the steepest mountains into terraced rice paddies. 174 00:25:59,480 --> 00:26:03,680 Today, subsistence farmers produce more than one million tonnes 175 00:26:03,680 --> 00:26:06,520 of rice here every year. 176 00:26:09,280 --> 00:26:11,600 MAN AND WOMAN SPEAKING 177 00:26:16,120 --> 00:26:19,160 Marivelo owns four paddy fields. 178 00:26:20,960 --> 00:26:24,240 Providing just enough rice for her family of ten. 179 00:26:46,560 --> 00:26:51,080 It's January, the height of the rainy season. 180 00:26:51,080 --> 00:26:54,080 And the most important time for any rice farmer. 181 00:26:58,640 --> 00:27:03,440 Each kilogram of rice needs more than 2,000 litres of water to grow. 182 00:27:06,200 --> 00:27:09,360 With rainwater flooding the rice paddies, 183 00:27:09,360 --> 00:27:12,400 Marivelo must prepare them for planting. 184 00:27:16,640 --> 00:27:21,800 But instead of using a plough, she uses her most prized possession. 185 00:27:28,000 --> 00:27:32,440 Originally from Asia, these are zebu cattle. 186 00:27:32,440 --> 00:27:34,320 MEN WHISTLING 187 00:27:47,520 --> 00:27:50,840 The stampeding hooves churn up the soil. 188 00:28:06,280 --> 00:28:09,040 It may be dangerous work, 189 00:28:09,040 --> 00:28:13,080 but it's an ancient practice unique to Madagascar. 190 00:28:21,880 --> 00:28:25,280 And brings the whole community together. 191 00:28:54,360 --> 00:28:59,440 With the soil prepared, it's time to get planting. 192 00:29:02,440 --> 00:29:04,920 To make the most of the peak rains, 193 00:29:04,920 --> 00:29:08,560 Marivelo and her daughters need to work fast. 194 00:29:11,520 --> 00:29:13,040 THEY CHEER 195 00:29:25,000 --> 00:29:26,840 They're precision planters. 196 00:29:29,480 --> 00:29:33,320 Every blade is 20 cm apart, 197 00:29:33,320 --> 00:29:36,120 ensuring maximum yield. 198 00:29:52,880 --> 00:29:55,000 ALL CHEERING 199 00:30:06,880 --> 00:30:12,080 In three months' time, the rice crop should be ready for harvest, 200 00:30:12,080 --> 00:30:16,800 providing Marivelo and her family with plenty of food for the year ahead. 201 00:30:18,800 --> 00:30:21,600 Unless the crop is struck by one 202 00:30:21,600 --> 00:30:25,160 of the most destructive creatures on the planet. 203 00:30:31,960 --> 00:30:33,280 Locusts. 204 00:30:40,600 --> 00:30:42,800 They're normally solitary insects. 205 00:30:44,240 --> 00:30:47,920 But when there's an abundance of crops, 206 00:30:47,920 --> 00:30:50,720 their numbers can reach plague proportions. 207 00:30:56,240 --> 00:31:01,480 These flightless hoppers can form armies over half a mile long. 208 00:31:07,800 --> 00:31:11,400 But they have only just begun on their path of destruction. 209 00:31:22,240 --> 00:31:24,280 At five weeks old, 210 00:31:24,280 --> 00:31:27,360 they morph into fully-fledged adults... 211 00:31:31,840 --> 00:31:35,480 ..and can take to the air in their billions. 212 00:31:50,080 --> 00:31:54,920 A swarm this size may only appear once in a decade in Madagascar. 213 00:32:08,120 --> 00:32:11,000 Travelling over 50 miles a day, 214 00:32:11,000 --> 00:32:14,840 they can devour 40,000 tonnes of vegetation... 215 00:32:19,520 --> 00:32:22,480 ..including the farmers' precious rice crops. 216 00:32:37,920 --> 00:32:39,800 On reaching the highlands, 217 00:32:39,800 --> 00:32:43,360 a plague is finally stopped 218 00:32:43,360 --> 00:32:45,120 by the heavy mountain rains. 219 00:32:47,120 --> 00:32:50,960 Wet wings prevent the locusts from flying, 220 00:32:50,960 --> 00:32:55,440 until, eventually, the swarm runs out of food, 221 00:32:55,440 --> 00:32:56,640 and dies. 222 00:33:09,920 --> 00:33:14,720 To the east of the highlands lies a completely different world. 223 00:33:19,720 --> 00:33:24,000 With warm, humid air blowing in off the Indian Ocean, it receives 224 00:33:24,000 --> 00:33:27,960 ten times the rainfall of the west, 225 00:33:27,960 --> 00:33:31,360 creating lush rainforests. 226 00:33:58,840 --> 00:34:03,080 When Madagascar's ancient castaways eventually reached these 227 00:34:03,080 --> 00:34:05,520 eastern forests, they flourished. 228 00:34:19,160 --> 00:34:22,760 Over time, creatures evolved in extraordinary ways... 229 00:34:25,640 --> 00:34:28,280 ..colonising every corner of the jungle. 230 00:34:32,160 --> 00:34:37,400 Today, two thirds of the island's plants and animals are found here. 231 00:34:48,680 --> 00:34:52,240 The forest floor is home to another ancient castaway, 232 00:34:52,240 --> 00:34:53,920 originally from Africa. 233 00:35:03,040 --> 00:35:06,160 It may look like a hedgehog, but this is a tenrec, 234 00:35:06,160 --> 00:35:09,720 found only on Madagascar. 235 00:35:19,480 --> 00:35:22,960 They give birth to more babies than any other mammal. 236 00:35:26,920 --> 00:35:30,240 As many as 32 in a single litter. 237 00:35:37,560 --> 00:35:42,200 Like lemurs, they've evolved into a wide variety of species... 238 00:35:43,880 --> 00:35:47,480 ..each adapting in remarkable ways to their forest home. 239 00:35:54,200 --> 00:35:56,840 At just four weeks old, 240 00:35:56,840 --> 00:36:00,120 these streaked tenrecs are almost fully grown... 241 00:36:03,320 --> 00:36:07,000 ..eagerly sniffing out a meal with their flexible snouts. 242 00:36:08,880 --> 00:36:13,320 To fuel their high metabolism, they can eat over 30 worms a day. 243 00:36:17,520 --> 00:36:19,040 And they quickly disperse. 244 00:36:43,760 --> 00:36:46,640 A deadly Madagascan ground boa. 245 00:37:01,800 --> 00:37:04,280 The mother tenrec senses danger 246 00:37:04,280 --> 00:37:06,120 and quickly sounds the alarm... 247 00:37:10,840 --> 00:37:14,640 ..by rubbing together modified spines on her back. 248 00:37:19,120 --> 00:37:23,520 The high pitched sounds cut through the clamour of the forest 249 00:37:23,520 --> 00:37:26,600 and the youngsters scurry back to her. 250 00:37:29,600 --> 00:37:32,840 SCRAPING 251 00:37:37,640 --> 00:37:40,480 This is a unique form of communication 252 00:37:40,480 --> 00:37:44,040 used by no other mammal on the planet, 253 00:37:44,040 --> 00:37:48,560 a bizarre adaptation to survive in these crowded forests. 254 00:37:59,560 --> 00:38:05,240 At night, an even stranger cast of creatures emerges. 255 00:38:14,840 --> 00:38:17,640 The aptly-named pelican spider. 256 00:38:20,680 --> 00:38:25,320 No larger than a grain of rice, he has a formidable set of jaws. 257 00:38:28,400 --> 00:38:31,040 This male is on the hunt for his next meal. 258 00:38:35,840 --> 00:38:40,440 Using his extra-long front legs, he searches for signs of life. 259 00:38:44,720 --> 00:38:45,960 A silk thread... 260 00:38:47,640 --> 00:38:49,600 ..is the perfect lead. 261 00:38:56,800 --> 00:38:59,440 A female orb web spider. 262 00:39:07,400 --> 00:39:09,880 But she's protected by her sticky web. 263 00:39:18,760 --> 00:39:20,360 What to do? 264 00:39:23,560 --> 00:39:26,080 Fortunately, the pelican spider 265 00:39:26,080 --> 00:39:30,120 has had millions of years to fine-tune its technique. 266 00:39:34,240 --> 00:39:37,640 Mimicking the movements of a fly caught in her web, 267 00:39:37,640 --> 00:39:39,680 he lures her towards him. 268 00:40:00,280 --> 00:40:04,240 He uses his massive jaws to keep her at a distance 269 00:40:04,240 --> 00:40:07,520 and avoid her lethal bite, 270 00:40:07,520 --> 00:40:11,920 then paralyses her with his own powerful venom, 271 00:40:11,920 --> 00:40:15,040 before tucking in. 272 00:40:23,400 --> 00:40:28,640 The intense competition for food in Madagascar's crowded rainforest 273 00:40:28,640 --> 00:40:33,080 has pushed its inhabitants to evolve in the most extreme ways... 274 00:40:36,400 --> 00:40:39,160 ..and the lemurs are no exception. 275 00:40:45,680 --> 00:40:47,640 This is an aye-aye, 276 00:40:47,640 --> 00:40:50,680 filmed in a special enclosure. 277 00:41:01,080 --> 00:41:04,800 Her favourite food is insect larvae, 278 00:41:04,800 --> 00:41:08,520 which can only be found deep inside the branches of trees. 279 00:41:12,520 --> 00:41:15,760 But the aye-aye has perfected a truly remarkable 280 00:41:15,760 --> 00:41:17,240 way of getting to them. 281 00:41:20,440 --> 00:41:24,480 It's a technique that's thought to take four years to master. 282 00:41:26,360 --> 00:41:30,000 Using her nine centimetre-long middle finger, 283 00:41:30,000 --> 00:41:33,000 she taps to hear where the branch is hollow. 284 00:41:36,720 --> 00:41:39,560 Then she gnaws away at the protective bark... 285 00:41:51,120 --> 00:41:54,760 ..before deploying her super-sized finger 286 00:41:54,760 --> 00:41:57,200 to fish out any juicy grubs. 287 00:42:12,440 --> 00:42:18,600 Madagascar's unique wildlife has had millions of years to slowly evolve. 288 00:42:23,000 --> 00:42:26,440 But in the last few thousand years, the pace of life 289 00:42:26,440 --> 00:42:29,280 has increased rapidly, 290 00:42:29,280 --> 00:42:31,760 with deadly consequences... 291 00:42:36,840 --> 00:42:42,360 ..as revealed by a recent discovery in Madagascar's most remote desert. 292 00:42:46,560 --> 00:42:51,760 This pool is a portal to a previously unexplored world. 293 00:43:06,080 --> 00:43:12,520 In 2015, divers first ventured into this network of flooded passages. 294 00:43:38,120 --> 00:43:40,160 50 metres below the surface, 295 00:43:40,160 --> 00:43:43,800 they entered a truly magical underworld... 296 00:43:46,040 --> 00:43:49,920 ..discovering more than 11 km of connected tunnels... 297 00:43:52,800 --> 00:43:56,640 ..and some of the largest underwater chambers in the world. 298 00:44:20,040 --> 00:44:24,640 But what they found inside these caves 299 00:44:24,640 --> 00:44:26,760 was even more remarkable... 300 00:44:27,960 --> 00:44:29,760 ..a vast graveyard... 301 00:44:31,360 --> 00:44:34,600 ..the preserved remains of mysterious creatures... 302 00:44:43,200 --> 00:44:45,960 ..four metre-long horned crocodiles... 303 00:44:56,320 --> 00:45:00,880 ..puma-like predators, and ancient pygmy hippos. 304 00:45:04,440 --> 00:45:06,920 But perhaps most impressive of all... 305 00:45:09,160 --> 00:45:15,040 ..the skulls of giant lemurs that grew to the size of a gorilla. 306 00:45:25,400 --> 00:45:27,600 All long gone. 307 00:45:30,280 --> 00:45:33,960 Their extinction coincided with the most disruptive 308 00:45:33,960 --> 00:45:36,520 change in Madagascar's long history... 309 00:45:38,360 --> 00:45:40,880 ..the arrival of people. 310 00:45:51,080 --> 00:45:56,520 And today, our impact on the island is greater than ever before. 311 00:45:59,760 --> 00:46:03,000 Madagascar's forests are disappearing faster than 312 00:46:03,000 --> 00:46:08,000 any other tropical country, cleared largely for subsistence farming. 313 00:46:13,160 --> 00:46:17,400 As little as 20% of the island's original forest remains. 314 00:46:27,400 --> 00:46:31,080 And the impact on Madagascar's unique wildlife 315 00:46:31,080 --> 00:46:32,880 has been devastating. 316 00:46:38,960 --> 00:46:44,200 95% of lemurs are now threatened with extinction... 317 00:46:48,360 --> 00:46:52,560 ..making them the most vulnerable group of mammals in the world. 318 00:47:10,440 --> 00:47:15,520 One of the most endangered is found in the east of the island... 319 00:47:18,120 --> 00:47:19,760 ..the greater bamboo lemur. 320 00:47:24,040 --> 00:47:27,920 Like all lemurs, they're highly-specialised. 321 00:47:37,240 --> 00:47:41,920 Bamboo makes up nearly 95% of their diet, 322 00:47:41,920 --> 00:47:45,680 despite being packed with deadly cyanide. 323 00:47:49,600 --> 00:47:51,880 Every day, a single lemur 324 00:47:51,880 --> 00:47:55,720 can eat enough poison to kill five humans. 325 00:47:58,400 --> 00:48:03,440 They have evolved to withstand its toxic effects, 326 00:48:03,440 --> 00:48:07,360 keeping these thickets all to themselves. 327 00:48:13,640 --> 00:48:18,840 But now, their unique adaptation has left them trapped here... 328 00:48:21,920 --> 00:48:23,920 ..unable to live anywhere else. 329 00:48:29,640 --> 00:48:33,920 As their bamboo forests are cleared for agriculture, 330 00:48:33,920 --> 00:48:37,760 these lemurs are left with nowhere to live, 331 00:48:37,760 --> 00:48:39,960 and little to eat. 332 00:48:43,040 --> 00:48:47,720 The greater bamboo lemur was once thought to have gone extinct. 333 00:48:51,040 --> 00:48:55,600 But thanks to a recent concerted effort to protect them, 334 00:48:55,600 --> 00:48:58,880 there is now a glimmer of hope. 335 00:49:09,840 --> 00:49:12,880 In the last year, this group 336 00:49:12,880 --> 00:49:16,920 had a record number of babies, 337 00:49:16,920 --> 00:49:23,120 adding 72 to their total population of 400. 338 00:49:34,080 --> 00:49:38,480 The island of Madagascar has reached a critical point. 339 00:49:42,560 --> 00:49:47,840 And only with intensive conservation efforts will its remarkable, 340 00:49:47,840 --> 00:49:50,320 and unique wildlife 341 00:49:50,320 --> 00:49:53,360 survive into the future. 342 00:50:11,440 --> 00:50:15,640 Filming the critically endangered greater bamboo lemur took 343 00:50:15,640 --> 00:50:19,960 the crew to one of the most remote regions of eastern Madagascar, 344 00:50:19,960 --> 00:50:24,040 only accessible by a challenging two-day drive. 345 00:50:27,760 --> 00:50:30,120 The road is deteriorating. 346 00:50:30,120 --> 00:50:33,400 The wooden bridges are getting narrower. 347 00:50:33,400 --> 00:50:36,800 The roads are worse than everyone expected. 348 00:50:36,800 --> 00:50:40,560 We appear to have already got one of our vehicles stuck. 349 00:50:41,520 --> 00:50:43,920 Finally, they reach Vohitrarivo, 350 00:50:43,920 --> 00:50:48,680 a village close to one of the last known refuges of this rare lemur. 351 00:50:50,960 --> 00:50:54,880 Over the next two weeks, the crew will be led by primatologist 352 00:50:54,880 --> 00:50:58,640 Delphine Roullet, who came here ten years ago on an urgent 353 00:50:58,640 --> 00:51:00,560 mission to save the bamboo lemurs. 354 00:51:10,760 --> 00:51:14,840 With the help of her organisation, around 400 lemurs now live 355 00:51:14,840 --> 00:51:19,600 in these pockets of bamboo forest, but they're spread over a vast area. 356 00:51:24,960 --> 00:51:29,320 Hopefully, we're nearly there and can stop climbing up the hills. 357 00:51:36,320 --> 00:51:38,320 To help narrow their search, 358 00:51:38,320 --> 00:51:43,240 they head into the bush to meet local lemur researcher Noret. 359 00:51:43,240 --> 00:51:46,400 Ahead of the shoot, he sets up camera traps to hopefully 360 00:51:46,400 --> 00:51:49,320 establish the lemurs' whereabouts. Let's see. 361 00:51:51,600 --> 00:51:52,760 Oh, what's that? 362 00:51:52,760 --> 00:51:54,440 There is one! 363 00:51:56,560 --> 00:51:58,080 It's a good sign. 364 00:51:58,080 --> 00:52:01,920 A troupe of bamboo lemurs were in the area just a few days ago. 365 00:52:01,920 --> 00:52:04,760 Oh, look, just here. Yeah, completely dark. 366 00:52:07,360 --> 00:52:11,920 But the lemurs can travel through these thickets with ease, so it will 367 00:52:11,920 --> 00:52:15,880 take all of Noret and Delphine's skills to track them down. 368 00:52:19,000 --> 00:52:21,400 I think Noret can see them. 369 00:52:22,760 --> 00:52:24,880 I can't see them. 370 00:52:24,880 --> 00:52:27,360 You can see a dark spot, just straight. 371 00:52:30,320 --> 00:52:33,200 They may have spotted them in the distance, 372 00:52:33,200 --> 00:52:38,680 but the lemurs are leading the crew into even thicker vegetation. 373 00:52:38,680 --> 00:52:43,520 I'm getting entangled in sticky grass, and it's dense here. 374 00:52:44,640 --> 00:52:46,560 No way this is going to work. 375 00:52:51,840 --> 00:52:54,080 After nearly a week of tracking, 376 00:52:54,080 --> 00:52:57,080 cameraman Justin is finally getting closer. 377 00:52:58,600 --> 00:53:02,960 But getting a clear shot of them remains a significant challenge. 378 00:53:04,920 --> 00:53:09,200 Yeah, right now there's two just below us, but we can't film it. 379 00:53:09,200 --> 00:53:11,400 There's too much vegetation. 380 00:53:13,240 --> 00:53:16,680 Their wild lemur chase eventually takes them to the 381 00:53:16,680 --> 00:53:20,920 edge of the bamboo forest and into the farmland beyond. 382 00:53:20,920 --> 00:53:24,800 Noret and the crew check in with the locals to get the latest 383 00:53:24,800 --> 00:53:26,600 information on any lemur sightings... 384 00:53:26,600 --> 00:53:29,880 SPEAKS LOCAL LANGUAGE 385 00:53:32,200 --> 00:53:35,720 ..only to stumble upon the lemurs right in front of them. 386 00:53:41,040 --> 00:53:44,360 So, we've just turned up to find them crossing this 387 00:53:44,360 --> 00:53:48,960 section of rice paddy, between one part of bamboo forest and another. 388 00:53:50,880 --> 00:53:54,880 With much of their bamboo forest cleared for agriculture, 389 00:53:54,880 --> 00:53:57,640 the lemurs are forced to venture into the open. 390 00:53:57,640 --> 00:54:01,560 Sort of surprising to find them here, because they really don't 391 00:54:01,560 --> 00:54:06,040 like dogs, and the villagers keep dogs, but so far they seem relaxed. 392 00:54:06,040 --> 00:54:08,880 Although bamboo is their preferred diet, 393 00:54:08,880 --> 00:54:12,960 the lemurs will sometimes resort to raiding rice crops. 394 00:54:12,960 --> 00:54:16,640 In the past, this has led to conflict with the locals, 395 00:54:16,640 --> 00:54:19,720 but Delphine's project has changed all that. 396 00:54:22,360 --> 00:54:25,960 Villagers like Noret are trained as lemur guardians. 397 00:54:29,600 --> 00:54:32,440 They help study the troupes and marshal them 398 00:54:32,440 --> 00:54:35,440 off farming land before any damage is caused. 399 00:54:39,560 --> 00:54:42,160 Justin is still trying to get his shot... 400 00:54:46,880 --> 00:54:51,000 ..when conditions take a turn for the worse. 401 00:54:51,000 --> 00:54:54,760 THUNDERCLAP 402 00:54:57,840 --> 00:55:01,280 The rain makes filming quite difficult, and it makes it 403 00:55:01,280 --> 00:55:05,280 really hard to keep everything and everybody dry, and not muddy. 404 00:55:05,280 --> 00:55:09,000 So, at the moment the lemurs are keeping their heads down, 405 00:55:09,000 --> 00:55:11,000 so we're doing the same. 406 00:55:15,920 --> 00:55:19,120 The lemurs may be close by, 407 00:55:19,120 --> 00:55:22,400 but the rain continues for four whole days. 408 00:55:25,840 --> 00:55:27,720 We're just having to sit out 409 00:55:27,720 --> 00:55:30,880 and hope they start moving somewhere we can see them. 410 00:55:30,880 --> 00:55:35,080 That frustration of having what you want, but not being able to see it. 411 00:55:35,080 --> 00:55:40,320 But all this rain brings about a surprising change to their fortunes. 412 00:55:40,320 --> 00:55:44,360 The rain triggers a flush of growth in the bamboo shoots, 413 00:55:44,360 --> 00:55:49,000 the lemurs' favourite food and draws them out into the open. 414 00:55:53,480 --> 00:55:56,560 So, it's been raining nonstop for five days now 415 00:55:56,560 --> 00:56:01,800 and I feel pretty wet from top to bottom. 416 00:56:04,280 --> 00:56:06,480 We can see six of them 417 00:56:06,480 --> 00:56:11,160 stuffing their faces with bamboo, which is a lovely sight to see. 418 00:56:11,160 --> 00:56:14,800 I'm really happy to be here, despite the rain. 419 00:56:14,800 --> 00:56:16,120 It's amazing. 420 00:56:18,080 --> 00:56:19,880 And there is an added bonus. 421 00:56:22,560 --> 00:56:27,000 The mother bamboo lemurs have timed their births to coincide with 422 00:56:27,000 --> 00:56:28,840 the arrival of fresh bamboo 423 00:56:28,840 --> 00:56:32,880 and the crew can film one of the first newborns of the season. 424 00:56:34,520 --> 00:56:36,720 Oh, it's so good to see the babies! Cute! 425 00:56:39,400 --> 00:56:42,840 Took a long time to get to this point of actually having them 426 00:56:42,840 --> 00:56:44,720 in front of us, so we can film them. 427 00:56:45,800 --> 00:56:48,560 It's just great to have moments like this. 428 00:56:48,560 --> 00:56:51,960 These rare and intimate portraits of baby lemurs is 429 00:56:51,960 --> 00:56:55,640 the start of a record breeding year. 430 00:56:56,880 --> 00:57:00,720 Over the following two months, 72 babies are born. 431 00:57:02,480 --> 00:57:05,760 It's a huge boost to this endangered population. 432 00:57:08,640 --> 00:57:11,680 But their future rests in the hands of the next 433 00:57:11,680 --> 00:57:13,720 generation of lemur guardians. 434 00:57:16,560 --> 00:57:19,600 A vital part of Noret and Delphine's work is 435 00:57:19,600 --> 00:57:24,280 sharing their knowledge with those living side by side with the lemurs. 436 00:57:41,560 --> 00:57:45,440 Thanks to Delphine, Noret, and their dedicated team, one 437 00:57:45,440 --> 00:57:49,440 of Madagascar's rarest lemurs is now back 438 00:57:49,440 --> 00:57:52,360 from the brink of extinction. 439 00:58:00,520 --> 00:58:02,680 Next time, Borneo... 440 00:58:05,200 --> 00:58:09,720 ..home to a staggering variety of habitats. 441 00:58:09,720 --> 00:58:12,240 From its bustling coral reefs 442 00:58:12,240 --> 00:58:15,480 and ancient rainforests, 443 00:58:15,480 --> 00:58:17,920 to its mountainous heart... 444 00:58:19,360 --> 00:58:22,960 ..Borneo holds possibly the greatest diversity of life... 445 00:58:24,600 --> 00:58:26,600 ..of any island.