1 00:00:25,720 --> 00:00:29,120 My mom moved us to Indonesia for a few years as a kid. 2 00:00:29,840 --> 00:00:33,200 We lived in a small house with the simple joys of nature. 3 00:00:33,880 --> 00:00:37,560 A mango tree out front, whiffs of fruits and spices. 4 00:00:38,840 --> 00:00:43,120 Paddy fields where water buffalo glanced up at you with mud-covered snouts. 5 00:00:44,040 --> 00:00:47,960 Indonesia is home to some of the most important forests 6 00:00:48,040 --> 00:00:50,080 and biodiversity in the world. 7 00:00:51,240 --> 00:00:55,000 And there's nothing like the Leuser Ecosystem, 8 00:00:55,080 --> 00:00:58,560 home to some of the most endangered species on Earth. 9 00:01:06,920 --> 00:01:09,840 The rain forests of Gunung Leuser National Park 10 00:01:11,560 --> 00:01:13,720 shelter countless plants and animals… 11 00:01:15,760 --> 00:01:18,320 each with a role to play. 12 00:01:31,800 --> 00:01:35,040 Leuser is also the last stronghold 13 00:01:35,120 --> 00:01:37,880 of four of the planet's most threatened species. 14 00:01:41,400 --> 00:01:43,520 Powerful and elusive tigers… 15 00:01:48,640 --> 00:01:50,680 …the world's smallest rhinos… 16 00:01:55,480 --> 00:01:57,360 …unique forest elephants… 17 00:02:00,440 --> 00:02:04,720 …and orangutans, one of the smartest great apes in the world. 18 00:02:08,960 --> 00:02:12,240 Once, these animals could be found together across southeast Asia. 19 00:02:14,680 --> 00:02:17,640 But deforestation and poaching means that, today, 20 00:02:18,600 --> 00:02:22,640 Leuser is the only place they still co-exist. 21 00:02:26,000 --> 00:02:29,800 Will we allow something so precious to disappear forever… 22 00:02:33,840 --> 00:02:36,360 or seize our last chance to protect it 23 00:02:36,440 --> 00:02:38,640 for our children and grandchildren? 24 00:02:40,520 --> 00:02:44,640 Join me in this most unique of wild spaces. 25 00:03:02,480 --> 00:03:06,920 On the Indonesian island of Sumatra lies a vast tropical rain forest 26 00:03:07,640 --> 00:03:11,960 and at its core, Gunung Leuser National Park. 27 00:03:14,360 --> 00:03:17,000 Here, forest-covered mountains dominate, 28 00:03:18,360 --> 00:03:20,440 reaching 10,000 feet tall. 29 00:03:21,000 --> 00:03:24,040 They safeguard its inhabitants like a fortress. 30 00:03:26,080 --> 00:03:32,120 But perhaps its greatest wildlife riches are found in its steamy lowland jungles. 31 00:03:47,200 --> 00:03:51,400 In Indonesian, "orangutan" means "person of the forest." 32 00:03:56,080 --> 00:04:01,440 And these trees are home to the densest population anywhere on Earth. 33 00:04:05,320 --> 00:04:06,760 This is their forest. 34 00:04:35,840 --> 00:04:37,640 There are several huge males. 35 00:04:38,600 --> 00:04:42,320 With large, flanged cheek pads, they're more attractive to mates. 36 00:04:48,720 --> 00:04:50,040 They're immensely powerful 37 00:04:51,760 --> 00:04:54,640 with a bite force stronger than a lion's. 38 00:04:58,200 --> 00:05:02,120 But there's an athletic and ambitious younger male coming up through the ranks. 39 00:05:12,560 --> 00:05:13,400 Rakus. 40 00:05:20,440 --> 00:05:24,720 His name, given to him by resident scientists, means "greedy." 41 00:05:26,360 --> 00:05:29,720 Because he likes to eat pretty much everything. 42 00:05:32,240 --> 00:05:33,440 Leaves, 43 00:05:34,800 --> 00:05:35,640 bark… 44 00:05:37,800 --> 00:05:38,640 fruit… 45 00:05:40,880 --> 00:05:42,280 termites. 46 00:05:43,920 --> 00:05:45,200 It's all on the menu. 47 00:05:47,720 --> 00:05:50,400 If this gourmet ape can eat enough, 48 00:05:50,480 --> 00:05:53,160 he may one day develop cheek pads 49 00:05:53,840 --> 00:05:55,280 like the most senior males. 50 00:06:00,880 --> 00:06:04,520 There's one food in particular that could fuel his ambition. 51 00:06:05,760 --> 00:06:06,760 The neesia fruit. 52 00:06:08,560 --> 00:06:10,040 About the size of a football, 53 00:06:10,560 --> 00:06:13,520 it's packed with large, tasty seeds. 54 00:06:22,000 --> 00:06:25,080 Before it ripens, it's as hard as concrete, 55 00:06:25,160 --> 00:06:27,280 making it nearly impossible to get into. 56 00:06:36,440 --> 00:06:38,800 Ripe neesia cracks open by itself. 57 00:06:41,800 --> 00:06:46,440 But the succulent seeds are surrounded with thousands of sharp, irritating hairs. 58 00:06:49,400 --> 00:06:52,040 To get this meal, Rakus must master 59 00:06:52,120 --> 00:06:54,840 the most sophisticated skill in the jungle. 60 00:06:58,880 --> 00:07:00,240 Many of the orangutans here 61 00:07:00,320 --> 00:07:04,040 use an ingenious way of avoiding the neesia's prickly hairs. 62 00:07:09,600 --> 00:07:11,000 First, they select a stick. 63 00:07:13,640 --> 00:07:17,720 Then, maneuvering it with their extremely versatile lips, 64 00:07:17,800 --> 00:07:20,760 they push it into the neesia's cracks. 65 00:07:26,800 --> 00:07:30,000 Repeated movement of the stick dislodges the seeds 66 00:07:30,920 --> 00:07:33,440 and in the process scrapes out the hairs… 67 00:07:37,840 --> 00:07:39,880 …making the fruit ready to eat. 68 00:07:44,560 --> 00:07:46,840 Orangutans are usually solitary animals. 69 00:07:48,080 --> 00:07:51,160 But the neesia tree comes into season only rarely. 70 00:07:52,560 --> 00:07:56,840 When it does, it draws in orangutans from far and wide. 71 00:08:00,520 --> 00:08:03,680 As they gather, there's a chance to learn from each other. 72 00:08:09,800 --> 00:08:11,640 Friska is a mature female 73 00:08:13,080 --> 00:08:15,320 and is expert at preparing the fruit. 74 00:08:18,160 --> 00:08:20,720 Rakus moves in for a masterclass. 75 00:08:30,400 --> 00:08:32,920 There's enough food around for him to be tolerated. 76 00:08:39,000 --> 00:08:41,240 These are the only wild orangutans 77 00:08:41,320 --> 00:08:44,640 known to create and use tools in this unique way. 78 00:08:52,680 --> 00:08:54,880 Rakus wants to have a go himself. 79 00:09:01,200 --> 00:09:03,800 Carefully, he crafts his tool. 80 00:09:09,600 --> 00:09:12,560 And Rakus selects the perfect neesia. 81 00:09:15,960 --> 00:09:18,600 Then it's down to trial and error. 82 00:09:26,440 --> 00:09:29,520 At last, with a little perseverance… 83 00:09:31,960 --> 00:09:34,800 Rakus gets the delicacy he's been craving. 84 00:09:43,320 --> 00:09:45,880 The more he perfects this extraordinary skill, 85 00:09:46,760 --> 00:09:48,640 the bigger and stronger he'll become. 86 00:09:52,720 --> 00:09:55,200 And one day, this greedy guy 87 00:09:56,600 --> 00:09:58,080 may just rise to the top. 88 00:10:06,120 --> 00:10:09,680 Leuser's abundance is partly thanks to its soil, 89 00:10:11,200 --> 00:10:15,360 which is up to six times more fertile than other rain forests in the region. 90 00:10:17,880 --> 00:10:19,880 And this is a reason why. 91 00:10:23,400 --> 00:10:26,040 One of the world's most active volcanoes. 92 00:10:27,640 --> 00:10:28,760 Mount Sinabung. 93 00:10:29,640 --> 00:10:33,720 For millennia, its eruptions have showered the area with volcanic ash… 94 00:10:37,280 --> 00:10:39,640 …rich in minerals and nutrients. 95 00:10:48,200 --> 00:10:50,400 The ash acts as a fertilizer, 96 00:10:50,480 --> 00:10:53,400 supporting a jungle of staggering complexity. 97 00:10:56,680 --> 00:10:58,760 With thousands of species of plants, 98 00:10:59,600 --> 00:11:02,440 it's one of the most diverse forests in the world. 99 00:11:12,680 --> 00:11:14,080 The titan arum. 100 00:11:19,640 --> 00:11:23,720 This is the largest flowering structure on the planet… 101 00:11:29,280 --> 00:11:30,840 …growing up to ten feet tall, 102 00:11:32,240 --> 00:11:33,840 the height of a basketball hoop. 103 00:11:39,560 --> 00:11:43,480 It only emerges after the plant has been growing for a decade. 104 00:11:48,760 --> 00:11:51,800 But producing this huge bloom saps a lot of energy. 105 00:11:55,040 --> 00:11:57,760 Flowering can only last two nights. 106 00:11:59,640 --> 00:12:01,040 So it has a clever way 107 00:12:01,120 --> 00:12:05,000 of rapidly attracting the insects it needs for pollination. 108 00:12:18,760 --> 00:12:20,920 It produces a powerful scent. 109 00:12:24,720 --> 00:12:26,480 But this is no fragrant beauty. 110 00:12:28,640 --> 00:12:30,960 It reeks of rotting flesh. 111 00:12:34,000 --> 00:12:36,560 The huge red bloom stretches up to five feet, 112 00:12:37,720 --> 00:12:41,040 adding to the illusion of a fresh animal corpse. 113 00:12:45,400 --> 00:12:49,920 Then as night falls, its greatest deception begins. 114 00:12:55,480 --> 00:12:57,440 Channeling ten years of stored energy, 115 00:12:58,080 --> 00:13:00,960 the arum pumps heat into its central column, 116 00:13:02,880 --> 00:13:05,080 becoming as hot as blood. 117 00:13:07,960 --> 00:13:13,000 Like a chimney, rising heat carries its stench up into the cool night air. 118 00:13:22,040 --> 00:13:24,040 For hundreds of scavenging insects, 119 00:13:24,120 --> 00:13:26,600 the draw is irresistible. 120 00:13:49,880 --> 00:13:52,920 They're lured into the arum's inner chamber. 121 00:13:56,200 --> 00:13:59,400 A cavern filled with male and female organs. 122 00:14:06,960 --> 00:14:10,200 As the insects search for the rotting meat they've been promised… 123 00:14:13,040 --> 00:14:16,480 they find themselves coated in pollen they will carry with them 124 00:14:16,560 --> 00:14:17,960 to other arums. 125 00:14:23,600 --> 00:14:26,360 And if they've already visited another of these giants, 126 00:14:26,920 --> 00:14:28,720 they will pollinate this plant. 127 00:14:35,480 --> 00:14:38,480 Ten years of preparation for a two-night show. 128 00:14:41,280 --> 00:14:43,880 The flower's energy is exhausted. 129 00:14:47,520 --> 00:14:49,000 The stragglers file out… 130 00:14:52,240 --> 00:14:53,160 before finally, 131 00:14:53,920 --> 00:14:55,400 in a matter of seconds… 132 00:14:59,520 --> 00:15:01,880 …the entire structure collapses. 133 00:15:06,400 --> 00:15:10,840 Successfully pollinated, another ten-year cycle is set in motion, 134 00:15:11,560 --> 00:15:13,880 toward more gigantic blooms. 135 00:15:29,040 --> 00:15:31,440 Even within Leuser's lowlands, 136 00:15:31,520 --> 00:15:34,360 there are extraordinarily different landscapes. 137 00:15:43,120 --> 00:15:46,640 The park's rivers transport its nutrient-rich soils 138 00:15:46,720 --> 00:15:48,240 downstream to the coast… 139 00:15:50,800 --> 00:15:53,360 where the forest meets the Indian Ocean… 140 00:15:57,800 --> 00:16:00,640 giving rise to a muddy mangrove swamp. 141 00:16:09,640 --> 00:16:10,600 A mudskipper. 142 00:16:16,400 --> 00:16:20,400 This fish is not confined to the life aquatic. 143 00:16:25,360 --> 00:16:26,880 Taking a big gulp of air… 144 00:16:30,280 --> 00:16:33,400 and using fins that have a shoulder joint, 145 00:16:34,840 --> 00:16:36,920 he propels himself around. 146 00:16:38,480 --> 00:16:41,640 A fish that can walk. 147 00:16:44,360 --> 00:16:47,400 He spends most of his life here on the mudflats. 148 00:16:50,080 --> 00:16:53,920 His periscope-like eyes have a lens like land-based animals, 149 00:16:54,680 --> 00:16:59,040 allowing him to see far better out of water than in. 150 00:17:04,440 --> 00:17:06,720 His favorite meal is a formidable foe 151 00:17:07,360 --> 00:17:09,200 with razor-sharp pincers. 152 00:17:12,240 --> 00:17:14,720 If he can catch one without getting nipped. 153 00:17:38,040 --> 00:17:39,320 Perhaps something softer? 154 00:17:48,280 --> 00:17:49,720 These crabs are very agile… 155 00:17:52,160 --> 00:17:54,680 especially for a fish out of water. 156 00:18:09,360 --> 00:18:12,960 Finally, all that remains is to disarm his prey. 157 00:18:16,280 --> 00:18:19,240 Holding it in his mouth, he uses a neat trick. 158 00:18:21,640 --> 00:18:25,280 Shake a crab hard enough and it will sacrifice its claw, 159 00:18:27,120 --> 00:18:28,000 the tastiest bit. 160 00:18:33,320 --> 00:18:35,160 But the loss is only temporary. 161 00:18:37,040 --> 00:18:40,160 Within a month, the crab will have grown a new claw. 162 00:18:43,840 --> 00:18:45,400 Maybe even bigger than before. 163 00:18:53,400 --> 00:18:58,000 For this land-loving fish, life is a never-ending crab-claw buffet. 164 00:19:12,560 --> 00:19:16,200 Heading inland, Leuser quickly becomes mountainous. 165 00:19:19,080 --> 00:19:22,080 The forest here is much more impenetrable. 166 00:19:23,560 --> 00:19:27,760 Steep hills provide a last refuge to Leuser's most endangered creature… 167 00:19:32,720 --> 00:19:35,720 the rarely-glimpsed and surprisingly small 168 00:19:37,440 --> 00:19:39,520 Sumatran rhinoceros. 169 00:19:42,880 --> 00:19:46,160 Although only four feet tall, it still weighs a ton. 170 00:19:47,120 --> 00:19:50,840 Perfect for bulldozing through thickets in search of lush foliage. 171 00:19:55,520 --> 00:19:59,040 By pruning plants, these rhinos benefit the forest, 172 00:19:59,120 --> 00:20:01,000 making room for new tree growth. 173 00:20:16,360 --> 00:20:20,600 They dig out mud wallows, which help them stay cool in the midday heat… 174 00:20:31,680 --> 00:20:33,840 …benefiting a range of neighbors. 175 00:20:41,640 --> 00:20:45,760 So the more rhinos, the healthier the whole forest becomes. 176 00:20:49,360 --> 00:20:51,680 Illegal hunting and habitat loss 177 00:20:51,760 --> 00:20:54,960 have reduced numbers to just a handful in the wild. 178 00:20:59,240 --> 00:21:02,960 To save them from extinction, rangers are constantly on patrol, 179 00:21:04,440 --> 00:21:05,640 deterring poachers 180 00:21:05,720 --> 00:21:10,240 and bringing the few remaining rhinos into captivity outside the park. 181 00:21:15,920 --> 00:21:19,840 These rhinos now live in large, guarded natural enclosures… 182 00:21:24,600 --> 00:21:25,880 where a breeding program 183 00:21:25,960 --> 00:21:29,120 hopes to reintroduce their descendants into Leuser… 184 00:21:32,320 --> 00:21:36,280 and eventually restore the balance of rain forest life. 185 00:21:44,680 --> 00:21:48,640 There are many extraordinary relationships between the creatures that live here. 186 00:21:49,800 --> 00:21:52,680 Some, we are only just discovering. 187 00:21:59,480 --> 00:22:01,560 Deep in Leuser's foothills, 188 00:22:01,640 --> 00:22:06,560 one of its smallest inhabitants is unwittingly helped 189 00:22:06,640 --> 00:22:07,920 by its largest. 190 00:22:17,960 --> 00:22:19,720 The Sumatran elephant. 191 00:22:46,800 --> 00:22:51,720 As they travel, they carve a network of pathways hundreds of miles long. 192 00:23:10,320 --> 00:23:14,280 Many species rely on these paths to get through the dense jungle. 193 00:23:20,120 --> 00:23:23,560 But one resident depends on these elephants more than most. 194 00:23:26,280 --> 00:23:27,240 A wart frog. 195 00:23:30,200 --> 00:23:32,160 She's only the size of a chicken's egg, 196 00:23:33,560 --> 00:23:35,680 but she has incredibly sharp senses. 197 00:23:37,640 --> 00:23:40,800 It's thought she detects vibrations of the approaching herd 198 00:23:41,560 --> 00:23:44,440 using special cavities in her lungs. 199 00:23:48,080 --> 00:23:50,040 You'd expect her to get out of the way. 200 00:23:51,920 --> 00:23:54,560 Instead, she heads towards them. 201 00:24:04,280 --> 00:24:05,960 Straight into the crush zone! 202 00:24:09,920 --> 00:24:12,800 But it's not the elephants themselves she's drawn to. 203 00:24:16,800 --> 00:24:19,800 The frog has a belly full of eggs, 204 00:24:20,840 --> 00:24:23,960 and she needs to lay them in still water. 205 00:24:30,320 --> 00:24:34,240 The elephant's footprints make the perfect pop-up nursery. 206 00:24:47,040 --> 00:24:49,960 She's given her eggs the best start in life 207 00:24:51,600 --> 00:24:53,120 and leaves them to hatch. 208 00:25:03,760 --> 00:25:06,360 Within two weeks, they've become tadpoles. 209 00:25:08,480 --> 00:25:11,120 But until they transform into froglets, 210 00:25:11,200 --> 00:25:14,640 survival in their flooded footprint is under threat. 211 00:25:18,040 --> 00:25:21,120 The tropical sun can quickly dry out these pools. 212 00:25:26,360 --> 00:25:32,040 So, if water levels drop, these tadpoles must get themselves out of trouble… 213 00:25:36,160 --> 00:25:38,520 by doubling the speed of their transformation. 214 00:25:40,480 --> 00:25:45,160 As froglets, they can finally escape the drying ponds. 215 00:25:53,160 --> 00:25:55,440 As long as they don't get squashed. 216 00:26:08,200 --> 00:26:11,320 Up in the treetops, the stakes are even higher. 217 00:26:17,720 --> 00:26:20,720 Many of Leuser's animals have mastered living up here. 218 00:26:27,240 --> 00:26:31,920 But perhaps none are more daring than the Thomas leaf monkey. 219 00:26:33,040 --> 00:26:34,600 Found only in Northern Sumatra, 220 00:26:35,320 --> 00:26:37,800 they roam in groups of up to 20. 221 00:26:39,560 --> 00:26:41,200 One male leads the troop, 222 00:26:42,360 --> 00:26:45,040 and the rest are females and young. 223 00:26:47,280 --> 00:26:49,760 The adults are supremely agile. 224 00:27:06,880 --> 00:27:09,000 Able to zip around the branches, 225 00:27:09,800 --> 00:27:12,440 they can leap large gaps with ease. 226 00:27:18,040 --> 00:27:21,800 But this two-year-old is still developing the strength in his leg muscles… 227 00:27:23,960 --> 00:27:27,480 and he can't navigate the canopy with the confidence of his elders. 228 00:27:29,920 --> 00:27:31,920 His mother used to carry him everywhere, 229 00:27:33,720 --> 00:27:35,360 but she has a new baby. 230 00:27:37,480 --> 00:27:41,240 And the youngster must now find his own way in the world. 231 00:27:42,800 --> 00:27:46,160 Today, he faces one of the biggest challenges of his life. 232 00:27:52,560 --> 00:27:55,400 The troop have exhausted supplies in this tree, 233 00:27:57,040 --> 00:27:58,240 so they have to move on. 234 00:28:00,480 --> 00:28:05,000 But it will take a giant leap across a gap of more than 20 feet. 235 00:28:09,800 --> 00:28:11,360 It's a three-story drop. 236 00:28:13,000 --> 00:28:13,840 One mistake 237 00:28:15,360 --> 00:28:16,320 could be fatal. 238 00:28:18,320 --> 00:28:22,040 The older monkeys have spent years perfecting such large jumps. 239 00:28:35,600 --> 00:28:39,960 Climbing to the topmost branches, they launch… 240 00:28:42,240 --> 00:28:45,080 maneuvering their limbs to control their descent. 241 00:28:57,160 --> 00:29:00,960 Even Mom, with her new baby on her belly, 242 00:29:02,280 --> 00:29:04,400 tackles the distance with grace. 243 00:29:13,040 --> 00:29:15,040 The two-year-old is up next. 244 00:29:26,680 --> 00:29:27,880 But it's all too much. 245 00:29:33,360 --> 00:29:36,040 With the rest of the troop feasting on the other side… 246 00:29:42,120 --> 00:29:43,000 …he's stranded. 247 00:29:48,680 --> 00:29:50,280 Mom can't come to his rescue. 248 00:29:55,720 --> 00:29:59,880 There's only one way to find out if he's got what it takes. 249 00:30:53,400 --> 00:30:54,240 Nailed it. 250 00:31:01,200 --> 00:31:05,800 The first of many such giant leaps he'll make on his journey to adulthood. 251 00:31:16,760 --> 00:31:18,720 And he gets a well-earned reward. 252 00:31:23,400 --> 00:31:25,200 Animals like the leaf monkeys 253 00:31:26,520 --> 00:31:29,520 help maintain the health of Leuser's rain forest, 254 00:31:30,360 --> 00:31:33,760 spreading seeds and natural fertilizers as they move. 255 00:31:40,320 --> 00:31:42,440 Every species here is important. 256 00:31:51,880 --> 00:31:53,080 Even the smallest 257 00:31:54,000 --> 00:31:57,880 that lurk in the dark underworld of the forest floor. 258 00:32:12,920 --> 00:32:15,880 The leafy gloom is home to a hunter, 259 00:32:16,920 --> 00:32:18,840 the hammerhead worm. 260 00:32:21,600 --> 00:32:25,440 This species of flatworm with its distinctive bands 261 00:32:26,040 --> 00:32:28,520 is so new it's yet to be named. 262 00:32:30,800 --> 00:32:33,480 As predators go, it's extremely small. 263 00:32:34,520 --> 00:32:36,040 The length of a fingernail. 264 00:32:37,440 --> 00:32:38,720 But it is deadly. 265 00:32:41,040 --> 00:32:44,280 It's on the hunt for a juicy slug or snail. 266 00:32:47,600 --> 00:32:49,080 They're everywhere in Leuser, 267 00:32:49,960 --> 00:32:52,480 devouring microscopic plants and organisms… 268 00:32:54,800 --> 00:32:58,080 and also the fungi that's essential for recycling plant debris. 269 00:33:08,400 --> 00:33:10,920 And this is where the hammerhead plays its part, 270 00:33:12,840 --> 00:33:17,600 keeping their numbers down, and so protecting the greenery. 271 00:33:20,480 --> 00:33:22,840 Using chemical sensors in its hammerhead, 272 00:33:24,760 --> 00:33:27,480 it tastes the ground for signs of a victim. 273 00:33:31,680 --> 00:33:36,240 Slugs and snails can't help but leave an unmissable trail of slime. 274 00:33:44,600 --> 00:33:46,920 With just a hint of a shell on its back, 275 00:33:47,640 --> 00:33:51,480 this curious creature is called a semi-slug. 276 00:33:52,920 --> 00:33:54,360 The perfect prey. 277 00:34:34,760 --> 00:34:39,440 Wrapping around its victim, the flatworm pumps out mucus to trap it. 278 00:34:43,680 --> 00:34:45,400 Once the prey is disabled, 279 00:34:45,480 --> 00:34:49,840 it attacks the semi-slug with toxins and digestive juices, 280 00:34:50,680 --> 00:34:52,080 breaking down its flesh… 281 00:34:56,840 --> 00:35:00,720 …finally, swallowing it through a mouth in the middle of its body. 282 00:35:06,400 --> 00:35:11,440 Within a matter of minutes, all that remains is the translucent shell. 283 00:35:26,840 --> 00:35:30,520 There are predators of all shapes and sizes across Leuser. 284 00:35:37,280 --> 00:35:41,760 But perhaps the most important sits right at the top of the food chain. 285 00:35:44,600 --> 00:35:47,960 To find it, you have to travel even higher… 286 00:35:50,240 --> 00:35:53,080 …to the remote, fortress-like mountaintop, 287 00:35:53,160 --> 00:35:55,080 which gives the park its name… 288 00:35:56,800 --> 00:35:57,720 Mount Leuser. 289 00:36:02,000 --> 00:36:04,880 Towering over 11,000 feet above sea level… 290 00:36:08,920 --> 00:36:10,480 often shrouded in mist… 291 00:36:14,920 --> 00:36:16,680 the forest is stunted… 292 00:36:19,680 --> 00:36:21,560 with patches of open moorland. 293 00:36:25,680 --> 00:36:28,520 It can be up to 60 degrees Fahrenheit colder here 294 00:36:28,600 --> 00:36:30,680 than the humid jungles far below. 295 00:36:38,320 --> 00:36:40,640 Only the toughest of plants can survive. 296 00:36:46,760 --> 00:36:49,640 Clinging onto the rocks, they hold the soil in place… 297 00:36:51,840 --> 00:36:54,720 preventing erosion and retaining rainwater, 298 00:36:54,800 --> 00:36:58,160 which then flows steadily into the forests far below. 299 00:37:07,520 --> 00:37:08,800 It's eerily quiet. 300 00:37:13,800 --> 00:37:16,920 Only a few animals venture this far up the mountain. 301 00:37:25,360 --> 00:37:30,600 The muntjac. A type of deer that browses on the moorland plants. 302 00:37:35,080 --> 00:37:38,360 Scientists hope research cameras might finally record 303 00:37:38,440 --> 00:37:40,520 the predator which hunts them… 304 00:37:42,640 --> 00:37:45,080 filming it here for the first time. 305 00:37:53,840 --> 00:37:55,640 But it is almost never seen. 306 00:38:00,960 --> 00:38:02,320 So it takes patience. 307 00:38:23,880 --> 00:38:24,800 At last… 308 00:38:27,680 --> 00:38:29,480 in a high mountain pasture… 309 00:38:32,480 --> 00:38:33,960 a Sumatran tiger. 310 00:38:41,000 --> 00:38:44,120 This adult male is checking out the scientific equipment 311 00:38:44,200 --> 00:38:45,320 left to record it. 312 00:38:50,000 --> 00:38:52,200 The terrain is so inaccessible 313 00:38:52,280 --> 00:38:56,720 that almost no studies have been made into the Sumatran tiger's behavior. 314 00:39:05,880 --> 00:39:09,280 But it's believed that as they patrol the mountaintops, 315 00:39:10,440 --> 00:39:15,640 these tigers stop deer and other animals from overgrazing the delicate vegetation. 316 00:39:28,400 --> 00:39:32,960 And these precious images prove that they're still here. 317 00:39:34,520 --> 00:39:36,320 As long as we protect the park, 318 00:39:36,400 --> 00:39:40,320 Sumatra's biggest cat can remain king of the jungle. 319 00:39:44,000 --> 00:39:47,640 While Leuser's mountainous terrain offers some natural protection… 320 00:39:50,080 --> 00:39:54,280 …on the fringes of the park, the risk to the wildlife is greater. 321 00:39:56,600 --> 00:40:01,240 Leuser's ecosystem continues into an area twice the size of the park. 322 00:40:03,400 --> 00:40:05,000 Much of it is protected… 323 00:40:07,520 --> 00:40:11,800 but millions of people live in towns and villages amongst these forests. 324 00:40:15,680 --> 00:40:17,880 So having the support of local communities 325 00:40:17,960 --> 00:40:21,760 is crucial to keeping Leuser's wildlife safe. 326 00:40:31,320 --> 00:40:33,920 Hidden in the trees on Leuser's southern border 327 00:40:35,120 --> 00:40:38,640 is a rarely-seen Sumatran slow loris. 328 00:40:43,640 --> 00:40:44,880 She's got huge eyes 329 00:40:45,720 --> 00:40:48,680 that help her to see in almost complete darkness. 330 00:40:52,080 --> 00:40:55,800 This mother has a young baby just a few weeks old, 331 00:40:57,440 --> 00:41:00,160 but he's already too big for her to carry as she feeds. 332 00:41:04,000 --> 00:41:05,680 Leaving him seems risky. 333 00:41:09,720 --> 00:41:12,360 Rival lorises can be viciously territorial. 334 00:41:16,080 --> 00:41:18,560 And the forest here is full of snakes. 335 00:41:22,640 --> 00:41:25,240 But lorises have a secret weapon. 336 00:41:28,600 --> 00:41:31,440 Their bite contains a deadly toxin, 337 00:41:32,920 --> 00:41:36,400 making them the only venomous primate on the planet. 338 00:41:39,280 --> 00:41:40,360 Even this youngster. 339 00:41:43,000 --> 00:41:45,920 So Mom can just hide him among the leaves 340 00:41:47,000 --> 00:41:48,920 while she goes foraging on her own. 341 00:41:54,760 --> 00:41:58,760 It's extremely unusual to see slow lorises venture to the ground. 342 00:42:02,280 --> 00:42:05,600 But she has to to get to one of her favorite foods, 343 00:42:06,560 --> 00:42:07,840 the calliandra. 344 00:42:11,080 --> 00:42:15,440 Its sweet-smelling nectar is packed with the energy she needs to nourish her baby. 345 00:42:19,240 --> 00:42:21,960 But these flowering bushes have been planted by farmers 346 00:42:23,320 --> 00:42:25,240 to shade their coffee crops. 347 00:42:26,760 --> 00:42:30,760 And lorises' proximity to humans has given them a problem. 348 00:42:32,480 --> 00:42:35,160 Traffickers in the illegal pet trade 349 00:42:35,840 --> 00:42:39,160 have hunted these cute creatures to the edge of extinction. 350 00:42:45,000 --> 00:42:49,400 But fortunately, this community is part of a new scheme that protects them. 351 00:42:53,600 --> 00:42:55,920 The farmers get a better price for their coffee 352 00:42:56,560 --> 00:42:58,720 for leaving the lorises alone. 353 00:43:02,160 --> 00:43:04,280 And the lorises help the farmers, 354 00:43:04,840 --> 00:43:06,720 because when they eat the calliandra, 355 00:43:07,440 --> 00:43:08,720 they pollinate it. 356 00:43:12,600 --> 00:43:15,760 As dawn approaches, she must return to her baby 357 00:43:17,120 --> 00:43:19,720 and get back to the business of being a mom. 358 00:43:29,400 --> 00:43:32,760 Local communities can also help to combat the biggest threat… 359 00:43:34,920 --> 00:43:36,080 deforestation. 360 00:43:39,640 --> 00:43:43,480 Leuser is so vast, it's almost impossible to patrol. 361 00:43:46,000 --> 00:43:47,520 Every single hour, 362 00:43:47,600 --> 00:43:50,280 more than a football field of forest is cleared, 363 00:43:51,200 --> 00:43:52,440 much of it illegally, 364 00:43:53,200 --> 00:43:55,920 to make room for growing palm oil. 365 00:43:59,280 --> 00:44:04,640 Palm oil is used in up to 50% of products on our supermarket shelves, 366 00:44:04,720 --> 00:44:06,880 from cookies to shampoo. 367 00:44:10,320 --> 00:44:13,360 These plantations are lifeless 368 00:44:13,440 --> 00:44:15,800 compared to the richness of the rain forest. 369 00:44:22,200 --> 00:44:26,320 But some communities are taking part in a fight back… 370 00:44:32,800 --> 00:44:35,680 …working with conservationists to remove the plantations. 371 00:44:41,240 --> 00:44:43,200 A small subsidy and a chance 372 00:44:43,280 --> 00:44:46,040 to grow a few profitable fruit trees within the forest 373 00:44:46,120 --> 00:44:49,600 gives an incentive and helps safeguard their futures. 374 00:45:09,640 --> 00:45:13,880 On the recovered land, Leuser quickly produces wonders. 375 00:45:16,600 --> 00:45:20,080 The wind brings seeds from healthy forests nearby. 376 00:45:23,440 --> 00:45:26,480 Microorganisms help to heal the soil. 377 00:45:27,120 --> 00:45:28,920 In just a matter of months, 378 00:45:29,000 --> 00:45:31,920 ferns and other plants grow over the old site. 379 00:45:35,080 --> 00:45:37,000 The pollinators move in. 380 00:45:38,440 --> 00:45:41,240 Mammals and birds spread more seeds. 381 00:45:46,680 --> 00:45:49,360 And in as little as four years, 382 00:45:49,440 --> 00:45:52,320 a thriving forest reappears. 383 00:45:59,000 --> 00:46:02,000 As it does so, animals start to return. 384 00:46:09,920 --> 00:46:13,120 Eventually, giant trees will grow. 385 00:46:15,240 --> 00:46:18,520 They'll absorb more and more carbon dioxide from our atmosphere, 386 00:46:19,320 --> 00:46:22,720 enriching it instead with oxygen, 387 00:46:23,720 --> 00:46:25,440 which benefits us all. 388 00:46:31,280 --> 00:46:33,320 By protecting this forest, 389 00:46:33,400 --> 00:46:36,840 Asia's most endangered creatures will still have a home. 390 00:46:43,200 --> 00:46:48,040 While still an infant, this Sumatran orangutan was taken from the forest 391 00:46:48,640 --> 00:46:50,400 and sold into the pet trade. 392 00:46:53,280 --> 00:46:55,200 After years of captivity, 393 00:46:55,280 --> 00:46:56,760 she was finally rescued 394 00:46:56,840 --> 00:47:01,280 and brought back to live freely again in the treetops. 395 00:47:07,320 --> 00:47:10,400 And now, she has another to care for. 396 00:47:17,040 --> 00:47:18,480 Less than two weeks old. 397 00:47:20,600 --> 00:47:24,360 So small she could fit in the palm of your hand. 398 00:47:28,600 --> 00:47:30,960 These tender moments are the beginnings 399 00:47:31,040 --> 00:47:34,720 of one of the closest mother/baby bonds in nature. 400 00:47:44,200 --> 00:47:45,160 For eight years, 401 00:47:45,720 --> 00:47:48,680 she will live within arm's reach of her mother, 402 00:47:50,640 --> 00:47:53,520 who will teach her everything she needs to survive. 403 00:47:56,960 --> 00:47:58,680 Gunung Leuser National Park 404 00:47:59,720 --> 00:48:02,160 and the vast ecosystem that surrounds it 405 00:48:03,320 --> 00:48:05,040 is a place of hope 406 00:48:06,880 --> 00:48:10,720 and an opportunity to protect its unique wildlife… 407 00:48:13,320 --> 00:48:17,040 in this, their last precious refuge. 408 00:48:20,640 --> 00:48:23,640 National parks are one of our greatest achievements. 409 00:48:25,840 --> 00:48:30,040 Over time, we've created nearly a quarter of a million protected spaces 410 00:48:30,120 --> 00:48:32,000 in almost every country on Earth. 411 00:48:40,640 --> 00:48:45,160 But in this world that's getting warmer and more crowded, we've got to do more. 412 00:48:49,960 --> 00:48:53,520 And if we're going to hang on to more of these wild places we depend on, 413 00:48:54,080 --> 00:48:56,000 each of us has a role to play. 414 00:48:57,360 --> 00:48:59,840 Demand to protect our last wildernesses 415 00:49:01,040 --> 00:49:02,320 for future generations. 416 00:49:05,720 --> 00:49:08,520 Campaign to create more, wherever you live, 417 00:49:09,640 --> 00:49:12,840 and insist they're accessible for everyone. 418 00:49:17,760 --> 00:49:21,400 Push your own communities to adopt smarter climate practices. 419 00:49:24,480 --> 00:49:27,840 And vote like the planet depends on it. 420 00:49:30,960 --> 00:49:32,760 There's no more time to waste. 421 00:49:33,440 --> 00:49:36,280 The world we leave to our children is too important. 422 00:49:37,360 --> 00:49:39,360 The time to act is now.