1 00:00:05,240 --> 00:00:09,200 Ten million species live on planet Earth. 2 00:00:10,600 --> 00:00:12,480 Each one is remarkable. 3 00:00:14,400 --> 00:00:16,840 But none can survive on its own. 4 00:00:19,600 --> 00:00:23,120 All life depends upon connections... 5 00:00:25,360 --> 00:00:28,440 ..unexpected, invariably complex, 6 00:00:28,440 --> 00:00:32,480 beautiful relationships between millions of plants and animals. 7 00:00:39,160 --> 00:00:42,280 This time, in our grasslands, 8 00:00:42,280 --> 00:00:47,480 I want to show you why these antelope need these rhino... 9 00:00:48,600 --> 00:00:51,400 ..why this lone wolf... 10 00:00:51,400 --> 00:00:53,640 needs an ant... 11 00:00:53,640 --> 00:00:54,840 SNARLS 12 00:00:54,840 --> 00:00:59,480 ..and the incredible secret that lies buried beneath them all. 13 00:01:00,600 --> 00:01:05,560 Connections like these create the planet's great ecosystems. 14 00:01:05,560 --> 00:01:08,880 They're vital for all life. 15 00:01:08,880 --> 00:01:13,160 I want to show you our world as you've never seen it before. 16 00:01:36,440 --> 00:01:38,480 Central Kenya... 17 00:01:40,680 --> 00:01:44,400 ..and this is whistling acacia grassland. 18 00:01:52,960 --> 00:01:56,000 The whistling actually comes from the breeze 19 00:01:56,000 --> 00:01:58,800 blowing across the holes in these hollow galls... 20 00:02:00,720 --> 00:02:06,600 ..and they're home to one of the grasslands' most intriguing creatures. 21 00:02:18,920 --> 00:02:23,200 This lizard is the aptly named dwarf gecko, 22 00:02:23,200 --> 00:02:27,040 and this one has laid a couple of eggs 23 00:02:27,040 --> 00:02:30,720 down here in this gall on the tree. 24 00:02:30,720 --> 00:02:33,480 The perfect place for a nest, you might think. 25 00:02:35,600 --> 00:02:39,240 But this tiny lizard can only safely lay its eggs here 26 00:02:39,240 --> 00:02:45,040 thanks to one of Africa's largest, most iconic and bizarre animals, 27 00:02:45,040 --> 00:02:47,160 the giraffe. 28 00:03:03,440 --> 00:03:09,240 The story of why the gecko needs the giraffe is wonderful, 29 00:03:09,240 --> 00:03:12,520 and it will take us on a journey across the world, 30 00:03:12,520 --> 00:03:16,400 to some of our most breathtaking grasslands. 31 00:03:30,840 --> 00:03:36,520 They are habitats which occupy a quarter of the land surface of our planet. 32 00:03:52,800 --> 00:03:57,400 They support some of our most spectacular wildlife... 33 00:04:00,520 --> 00:04:05,640 and yet grasslands lack one of the basic ingredients for life... 34 00:04:09,600 --> 00:04:12,800 ..a truly precious element. 35 00:04:14,480 --> 00:04:16,520 It's this - 36 00:04:18,560 --> 00:04:20,240 nitrogen, 37 00:04:20,240 --> 00:04:22,600 a colourless, tasteless gas. 38 00:04:23,680 --> 00:04:29,320 It's only when we chill it down to 196 degrees below zero 39 00:04:29,320 --> 00:04:31,360 that we can actually see it. 40 00:04:32,360 --> 00:04:34,040 I can tell you 41 00:04:34,040 --> 00:04:38,280 that almost everything that happens out here in this grassland ecosystem 42 00:04:38,280 --> 00:04:43,160 is governed by a craving for this rare resource. 43 00:04:43,160 --> 00:04:47,640 In fact, I'd go so far as to say that grasslands can only function 44 00:04:47,640 --> 00:04:52,120 because they can cope so ingeniously with so little of it. 45 00:04:52,120 --> 00:04:56,960 So, for once, perhaps this will make the ecologist's job a little easier, 46 00:04:56,960 --> 00:05:00,920 because to understand how grasslands work, 47 00:05:00,920 --> 00:05:04,640 all we need to do is follow the nitrogen. 48 00:05:16,040 --> 00:05:18,080 Australia. 49 00:05:32,640 --> 00:05:38,760 The grasslands here have some of the lowest levels of nitrogen on the planet, 50 00:05:38,760 --> 00:05:45,480 which makes the local wildlife perfect for demonstrating why it's so important. 51 00:05:48,840 --> 00:05:52,240 Nitrogen is the magic ingredient. 52 00:05:52,240 --> 00:05:56,800 When you add it to carbohydrate, you get protein. 53 00:05:56,800 --> 00:06:00,360 And protein is what you need to make living tissue. 54 00:06:00,360 --> 00:06:05,960 Protein is the building block for life, all life. 55 00:06:13,720 --> 00:06:16,760 A baby eastern grey kangaroo. 56 00:06:21,880 --> 00:06:26,920 When he was born, he weighed less than a one-pence piece. 57 00:06:35,080 --> 00:06:40,000 His dad, on the other hand, is one of the heaviest marsupials in the world. 58 00:06:42,960 --> 00:06:47,000 Which means that joey has a lot of growing up to do. 59 00:06:56,120 --> 00:06:59,520 In fact, from birth to adulthood, 60 00:06:59,520 --> 00:07:04,080 he'll increase his body size by 100,000 times. 61 00:07:08,200 --> 00:07:12,440 And all of that will be built with protein. 62 00:07:14,240 --> 00:07:18,240 And you can't make protein without nitrogen. 63 00:07:24,440 --> 00:07:29,600 Right now, he gets most of his protein from his mother, 64 00:07:29,600 --> 00:07:34,360 and she gets all of her protein from a diet of grass. 65 00:07:38,560 --> 00:07:42,320 At the moment, these kangaroos are just hanging out, 66 00:07:42,320 --> 00:07:46,520 and they look like a typical population of kangaroos, 67 00:07:46,520 --> 00:07:49,800 but I can assure you they're not. 68 00:07:51,440 --> 00:07:54,920 Because this is not your typical Australian grassland. 69 00:07:56,400 --> 00:07:59,160 It's Anglesea Golf Club near Melbourne. 70 00:08:08,720 --> 00:08:14,000 Kangaroos were here when the golf course was built 60 years ago, 71 00:08:14,000 --> 00:08:17,000 but since then, their population has boomed. 72 00:08:21,000 --> 00:08:25,320 At a recent count, there were 359 of them. 73 00:08:26,360 --> 00:08:29,400 That's nearly 20 for each hole. 74 00:08:33,320 --> 00:08:39,560 And the secret of their success is down to these immaculate fairways. 75 00:08:45,040 --> 00:08:51,960 This grass is so green and so lush because it's had something added to it. 76 00:08:51,960 --> 00:08:54,600 This. 77 00:08:54,600 --> 00:08:56,600 Nitrogen fertiliser. 78 00:08:58,040 --> 00:09:00,880 And I know it's a product of the industrial revolution 79 00:09:00,880 --> 00:09:03,360 that's therefore led to all of this lushness, 80 00:09:03,360 --> 00:09:10,080 but it certainly proves a point - the power of nitrogen in a grassland. 81 00:09:14,280 --> 00:09:16,760 It's added once a month. 82 00:09:16,760 --> 00:09:20,520 It seeps into the soil, is quickly taken up by the roots 83 00:09:20,520 --> 00:09:28,120 and then converted into proteins for stronger, healthier grass. 84 00:09:31,280 --> 00:09:35,440 Great for golf but perfect for the joey. 85 00:09:38,480 --> 00:09:43,120 The extra protein means that he can grow faster, 86 00:09:43,120 --> 00:09:46,800 become healthier and live longer 87 00:09:48,200 --> 00:09:51,600 and that's the power of nitrogen. 88 00:10:07,520 --> 00:10:10,920 On the plains of East Africa, there's an animal 89 00:10:10,920 --> 00:10:15,240 that you might think is the least likely to be affected 90 00:10:15,240 --> 00:10:17,680 by nitrogen levels in the grassland. 91 00:10:26,840 --> 00:10:28,840 SNARLING 92 00:10:28,840 --> 00:10:31,600 Nitrogen, or indeed the lack of it, 93 00:10:31,600 --> 00:10:34,960 plays a decisive role in any grassland ecosystem. 94 00:10:34,960 --> 00:10:39,800 It's even intrinsically entwined with the ecology of large predators 95 00:10:39,800 --> 00:10:41,600 like these lions. 96 00:10:43,880 --> 00:10:45,320 GROWLING 97 00:10:46,320 --> 00:10:48,640 This close, and I'm in no doubt 98 00:10:48,640 --> 00:10:53,600 that these animals are at the very top of their food chain. 99 00:10:56,280 --> 00:10:59,960 But to find out how nitrogen affects predators, 100 00:10:59,960 --> 00:11:03,160 I need to start at the bottom of the food chain... 101 00:11:11,320 --> 00:11:14,560 ..and it all begins with a very special plant... 102 00:11:16,800 --> 00:11:21,440 ..one of the great unsung heroes of our planet, 103 00:11:21,440 --> 00:11:23,440 grass. 104 00:11:27,680 --> 00:11:30,400 The really great thing about grass is that it's simple. 105 00:11:30,400 --> 00:11:35,160 Compared to other flowering plants, shrubs and trees, 106 00:11:35,160 --> 00:11:37,920 it requires minimal protein to build. 107 00:11:37,920 --> 00:11:41,120 So it can take all of the nitrogen from its roots 108 00:11:41,120 --> 00:11:46,880 and put it not into bulky structures but organise it efficiently, yet simply, 109 00:11:46,880 --> 00:11:50,720 to maximise photosynthesis to produce its food. 110 00:11:51,760 --> 00:11:56,760 So grass leaves have protein at much lower concentrations. 111 00:11:58,040 --> 00:12:02,080 But this gives grazing animals a real problem. 112 00:12:04,440 --> 00:12:09,160 Impala are one of Africa's commonest antelope, 113 00:12:09,160 --> 00:12:11,240 a favourite prey of big cats. 114 00:12:18,000 --> 00:12:22,000 But their biggest challenge is a much more basic one... 115 00:12:23,800 --> 00:12:27,480 ..how to survive on nothing more than grass. 116 00:12:29,120 --> 00:12:33,640 The key is being very fussy about the sort of grass you eat, 117 00:12:33,640 --> 00:12:38,720 because some grass is richer in nitrogen than other grass. 118 00:12:38,720 --> 00:12:42,480 This impala is actually cherry-picking the leaves 119 00:12:42,480 --> 00:12:45,400 with the highest concentration of nitrogen. 120 00:12:48,840 --> 00:12:52,040 Even so, she'll have to work hard to extract it. 121 00:12:56,080 --> 00:12:58,560 Just watch her neck closely. 122 00:12:59,720 --> 00:13:02,800 Any moment now, she's going to regurgitate 123 00:13:02,800 --> 00:13:05,440 a ball of partially digested grass... 124 00:13:10,160 --> 00:13:13,200 ..and she'll process it all over again. 125 00:13:17,800 --> 00:13:20,680 It's called chewing the cud. 126 00:13:20,680 --> 00:13:24,080 By digesting grass not once... 127 00:13:25,880 --> 00:13:26,800 ..but twice, 128 00:13:26,800 --> 00:13:31,880 these animals can extract as much of the nitrogen as possible, 129 00:13:31,880 --> 00:13:34,400 but it still only works on the very best grass. 130 00:13:35,840 --> 00:13:37,800 Antelope, like these impala, 131 00:13:37,800 --> 00:13:42,320 can only survive on a diet of grass which is relatively high in nitrogen - 132 00:13:42,320 --> 00:13:46,280 grass like this. We call it sweet grass. 133 00:13:49,000 --> 00:13:54,040 This long grass, on the other hand, is known as sour grass, 134 00:13:54,040 --> 00:13:59,360 because the nitrogen in its leaves occurs at even lower concentrations. 135 00:14:03,760 --> 00:14:06,040 Antelope can't live here. 136 00:14:06,040 --> 00:14:11,280 They simply can't get enough nitrogen out of sour grass to survive. 137 00:14:25,520 --> 00:14:28,720 But there is an animal here that can change that... 138 00:14:29,840 --> 00:14:32,160 ..a very rare one. 139 00:14:32,160 --> 00:14:34,680 This is what I've been looking for. 140 00:14:37,480 --> 00:14:40,440 The animal that has deposited this dung 141 00:14:40,440 --> 00:14:44,840 processes grass through its gut in a very different way than antelope, 142 00:14:44,840 --> 00:14:46,600 and I'm sure I can demonstrate that. 143 00:14:46,600 --> 00:14:49,880 Here is some antelope poo, 144 00:14:49,880 --> 00:14:55,560 and if I take just one of these and break it open here, 145 00:14:55,560 --> 00:15:01,640 you can see that what remains is pretty much nothing more than dust. 146 00:15:03,280 --> 00:15:06,520 Whereas this, on the other hand, is very different. 147 00:15:07,920 --> 00:15:09,960 If I break this one in half... 148 00:15:11,240 --> 00:15:14,400 ..the grass is still very visible. 149 00:15:37,400 --> 00:15:39,800 RHINO SNORTS 150 00:15:46,320 --> 00:15:48,080 The white rhino. 151 00:15:48,080 --> 00:15:50,320 What an animal! 152 00:15:54,480 --> 00:15:55,680 Their sheer scale... 153 00:15:55,680 --> 00:15:58,560 I mean, they're the closest thing perhaps that we have on the planet 154 00:15:58,560 --> 00:16:01,000 to mammalian dinosaurs. 155 00:16:01,000 --> 00:16:04,800 And of course, they have a reputation for being pretty feisty, 156 00:16:04,800 --> 00:16:10,280 so I'm being very careful and not moving too quickly and keeping my voice down. 157 00:16:10,280 --> 00:16:13,560 In fact, this one's getting a little bit close, 158 00:16:13,560 --> 00:16:17,680 so I'm going to stop moving and talk...talking altogether. 159 00:16:20,720 --> 00:16:26,800 Their eyesight is poor, so if I'm still, they may not notice me. 160 00:16:33,080 --> 00:16:35,600 But they do have a great sense of smell. 161 00:16:41,560 --> 00:16:44,840 If the wind changes, they could charge. 162 00:17:05,520 --> 00:17:07,960 Absolutely fabulous things. 163 00:17:16,320 --> 00:17:19,360 Now, one of these animals has got no horns. 164 00:17:19,360 --> 00:17:21,400 It hasn't lost them in a scrap. 165 00:17:21,400 --> 00:17:24,480 They've been deliberately removed by the park rangers here, 166 00:17:24,480 --> 00:17:27,600 as these horns can have a tremendous value. 167 00:17:31,360 --> 00:17:35,440 Rhinos with horns are prized by poachers. 168 00:17:35,440 --> 00:17:39,520 The month before I arrived, they killed one in this very park. 169 00:17:41,720 --> 00:17:45,400 Cutting off her horn could save her life, 170 00:17:45,400 --> 00:17:51,240 and it's hoped that this practice will save the entire species. 171 00:17:53,680 --> 00:17:55,720 Losing a species like this 172 00:17:55,720 --> 00:18:00,000 would have a drastic impact on the entire grassland ecosystem. 173 00:18:03,520 --> 00:18:09,880 Her huge size allows her to live on grass where antelope just can't. 174 00:18:12,000 --> 00:18:15,840 Her body houses a massive gut, a fermentation chamber, 175 00:18:15,840 --> 00:18:19,520 so she can make up for the low quality of sour grass 176 00:18:19,520 --> 00:18:22,800 by digesting vast quantities of it. 177 00:18:28,400 --> 00:18:33,240 All of which means she produces a lot of dung... 178 00:18:38,240 --> 00:18:42,960 ..which she drops in a very specific place - 179 00:18:42,960 --> 00:18:45,160 a midden. 180 00:18:45,160 --> 00:18:49,320 For rhinos, this is important. It's how they communicate. 181 00:18:55,240 --> 00:18:58,080 Rhinos come here from far and wide. 182 00:18:59,120 --> 00:19:03,160 By smelling the pile, they can tell who's around, 183 00:19:03,160 --> 00:19:06,400 how they're doing and who is ready to mate. 184 00:19:11,040 --> 00:19:15,840 It's a sort of faecal Facebook but with added value. 185 00:19:18,760 --> 00:19:24,920 It brings nitrogen-rich manure from all over the grassland to one place. 186 00:19:29,800 --> 00:19:34,040 So the grass growing here becomes increasingly sweeter 187 00:19:34,040 --> 00:19:38,320 until, as if by magic, rhinos have created 188 00:19:38,320 --> 00:19:41,280 a grazing lawn of sweet grass, 189 00:19:41,280 --> 00:19:44,360 perfect for fussy eaters like impala. 190 00:19:58,360 --> 00:20:05,880 Rhinos are ecosystem engineers upon which many other animals depend. 191 00:20:05,880 --> 00:20:09,400 That, surely, is their true value. 192 00:20:09,400 --> 00:20:14,640 That's why they're worth much more alive than dead. 193 00:20:21,960 --> 00:20:23,840 Right across the world, 194 00:20:23,840 --> 00:20:28,480 it's sweet grass that is crucial for most grassland grazers... 195 00:20:29,600 --> 00:20:32,960 ..and it's this quest for sweet grass 196 00:20:32,960 --> 00:20:37,600 that drives one of the largest movements of animals on our planet. 197 00:20:48,800 --> 00:20:54,040 Every year, one and a half million wildebeest migrate 3,000 kilometres, 198 00:20:54,040 --> 00:20:57,280 all because of nitrogen. 199 00:20:59,360 --> 00:21:03,640 And this is when its impact reaches the top of the food chain. 200 00:21:20,600 --> 00:21:22,920 INSECTS BUZZING 201 00:21:48,960 --> 00:21:51,560 BONES CRUNCHING 202 00:21:53,200 --> 00:21:57,640 So, what has a lion kill got to do with nitrogen? 203 00:21:57,640 --> 00:22:00,440 Well, basically two things. 204 00:22:00,440 --> 00:22:03,400 You see, the lions here have identified 205 00:22:03,400 --> 00:22:08,760 the richest source of nitrogen available out here in the grassland - 206 00:22:08,760 --> 00:22:10,720 large herbivores. 207 00:22:10,720 --> 00:22:14,160 You see, their bodies are made up of principally proteins, 208 00:22:14,160 --> 00:22:17,520 and that protein is where the nitrogen is. 209 00:22:19,000 --> 00:22:25,080 Then it's the sweet grass which dictates where lions like to hunt. 210 00:22:27,840 --> 00:22:29,800 PURRS 211 00:22:31,160 --> 00:22:36,960 King of beasts they may be, but their lives are ruled by nitrogen. 212 00:22:38,080 --> 00:22:41,960 But how would a grassland predator survive 213 00:22:41,960 --> 00:22:45,360 if there were no sweet grass to hunt in? 214 00:23:06,560 --> 00:23:12,040 Depending on where you are in the world, the grassland always has a special name. 215 00:23:12,040 --> 00:23:14,240 In Africa, the savannah. 216 00:23:14,240 --> 00:23:16,280 In the US, it's the prairies. 217 00:23:16,280 --> 00:23:19,480 Here in South America, it's the cerrado. 218 00:23:24,120 --> 00:23:26,920 There's one animal that lives here that I'd love to show you. 219 00:23:26,920 --> 00:23:29,280 It's...it's really special. 220 00:23:29,280 --> 00:23:30,880 I've never seen one in the wild, 221 00:23:30,880 --> 00:23:34,320 but it's a truly fantastic animal by anyone's standards. 222 00:23:37,560 --> 00:23:40,080 This is Emas National Park. 223 00:23:43,480 --> 00:23:47,320 The name comes from the Brazilian for this bird... 224 00:23:48,720 --> 00:23:50,160 ..the rhea. 225 00:23:54,440 --> 00:23:56,440 BIRDSONG 226 00:23:59,320 --> 00:24:02,160 But it's not a rhea that I'm after. 227 00:24:03,960 --> 00:24:06,160 What I'm after is a wolf. 228 00:24:10,440 --> 00:24:14,560 Maned wolves are one of the largest predators in South America, 229 00:24:14,560 --> 00:24:18,600 but their home ranges, their territories, are huge, 230 00:24:18,600 --> 00:24:21,040 so they're not easy to find or see. 231 00:24:36,080 --> 00:24:39,560 This wolf has a problem on her paws. 232 00:24:45,040 --> 00:24:49,840 You see, these grasslands are so low in nitrogen 233 00:24:49,840 --> 00:24:53,320 that they can't support herds of grazing animals, 234 00:24:53,320 --> 00:24:55,560 like impala or wildebeest. 235 00:25:02,480 --> 00:25:05,720 In fact, the wolf's survival here 236 00:25:05,720 --> 00:25:08,120 is all thanks to a relationship 237 00:25:08,120 --> 00:25:11,760 with one of the cerrado's smallest inhabitants. 238 00:25:13,240 --> 00:25:14,920 It's this, an ant. 239 00:25:16,360 --> 00:25:21,360 And the story of why the wolf needs the ant is an amazing one, 240 00:25:21,360 --> 00:25:23,040 and it's all down to the way 241 00:25:23,040 --> 00:25:26,440 that grassland ecosystems survive against the odds. 242 00:25:28,920 --> 00:25:34,600 Other species of canids - dogs, wolves - hunt in packs, 243 00:25:34,600 --> 00:25:37,600 but her life is a lonely one. 244 00:25:41,240 --> 00:25:46,880 There's just not enough nitrogen here for even two maned wolves, 245 00:25:46,880 --> 00:25:48,800 so one of them has to go. 246 00:26:18,720 --> 00:26:23,920 Hunting on her own means that even the odd deer is off the menu. 247 00:26:25,440 --> 00:26:28,880 Instead, she has to catch more modest prey. 248 00:27:24,280 --> 00:27:28,920 She may have walked miles just for that mouse... 249 00:27:31,360 --> 00:27:34,880 ..and such meagre pickings won't sustain a wolf. 250 00:27:37,480 --> 00:27:42,720 So she has put herself on a bizarre dietary supplement. 251 00:27:51,640 --> 00:27:56,360 This is a lobeira fruit, from the word "lobo", which means wolf, 252 00:27:56,360 --> 00:27:59,000 and wolves love these things. 253 00:28:05,120 --> 00:28:07,720 They make the perfect midnight snack. 254 00:28:16,920 --> 00:28:20,520 Lobeira fruit make up about half of her diet. 255 00:28:22,160 --> 00:28:24,560 True, they don't have much nitrogen, 256 00:28:24,560 --> 00:28:28,240 but they are packed with vitamins and carbohydrates. 257 00:28:30,200 --> 00:28:34,720 So eating fruit means she needs to catch fewer mice. 258 00:28:34,720 --> 00:28:35,800 SNIFFING 259 00:28:35,800 --> 00:28:38,360 And that actually means that she can survive 260 00:28:38,360 --> 00:28:41,720 in this nitrogen-starved grassland. 261 00:28:47,320 --> 00:28:50,360 But it gets even better. 262 00:28:51,560 --> 00:28:55,960 The maned wolf is also helping the fruit. 263 00:28:57,320 --> 00:29:01,640 Wolves like to mark their territory, and maned wolves are no exception, 264 00:29:01,640 --> 00:29:05,000 and they like to choose high spots to do so. 265 00:29:05,000 --> 00:29:08,040 But, of course, here on the flat cerrado, 266 00:29:08,040 --> 00:29:10,480 such places are in short supply. 267 00:29:10,480 --> 00:29:12,640 So, the one they turn to is this, 268 00:29:12,640 --> 00:29:17,800 and this mound of soil here is the nest of leaf-cutter ants. 269 00:29:22,920 --> 00:29:27,560 When the wolf poos on the mound, it has an immediate effect. 270 00:29:38,720 --> 00:29:42,360 Soon most of the colony are out in force. 271 00:29:51,040 --> 00:29:53,600 The ants will salvage anything. 272 00:29:53,600 --> 00:29:56,200 They'll even try what's left of a mouse. 273 00:30:07,200 --> 00:30:10,840 But one of them has just found the real prize... 274 00:30:12,400 --> 00:30:15,400 ..a seed from the lobeira fruit. 275 00:30:34,200 --> 00:30:39,440 The nutrient-rich coating from these seeds will be fed to the ant larvae. 276 00:30:58,760 --> 00:31:03,960 And, buried in the safety of the nest, those seeds will germinate. 277 00:31:03,960 --> 00:31:06,520 They've even got added fertiliser. 278 00:31:07,600 --> 00:31:09,560 So what we have here is an interaction 279 00:31:09,560 --> 00:31:13,280 between three totally disparate species - 280 00:31:13,280 --> 00:31:16,160 the ant, the fruit and the wolf. 281 00:31:17,080 --> 00:31:20,680 Now, the ants, they get food delivered straight to their door. 282 00:31:20,680 --> 00:31:24,200 The fruit has found something to disperse its seeds 283 00:31:24,200 --> 00:31:27,960 and something else to ensure that they germinate perfectly. 284 00:31:27,960 --> 00:31:33,080 And the wolves? Well, they're effectively farming their own food. 285 00:31:34,120 --> 00:31:36,000 What a story. What a story! 286 00:31:36,000 --> 00:31:37,840 It's stories like that 287 00:31:37,840 --> 00:31:39,840 that mean that you can always entertain 288 00:31:39,840 --> 00:31:41,720 a lifelong fascination with nature. 289 00:31:41,720 --> 00:31:47,120 And, you know, every single leaf-cutter ant nest out here on the cerrado 290 00:31:47,120 --> 00:31:50,120 has a lobeira fruit tree growing next to it. 291 00:31:51,120 --> 00:31:52,800 It works. 292 00:31:52,800 --> 00:31:56,080 And, you know, the most exciting thing for me 293 00:31:56,080 --> 00:31:58,280 is that none of the players in this system, 294 00:31:58,280 --> 00:31:59,920 the ant, the fruit or the wolf, 295 00:31:59,920 --> 00:32:03,120 has any knowledge or regard for what it's doing, 296 00:32:03,120 --> 00:32:06,400 and yet it works perfectly. 297 00:32:06,400 --> 00:32:08,440 Fantastic. 298 00:32:15,040 --> 00:32:20,040 These connections are not just important for the creatures concerned. 299 00:32:20,040 --> 00:32:23,960 Because of the way they move precious nitrogen around, 300 00:32:23,960 --> 00:32:28,160 they are crucial for the entire grassland ecosystem. 301 00:32:44,840 --> 00:32:49,760 Relationships between species evolve over millennia, 302 00:32:49,760 --> 00:32:53,520 but they can be destroyed in just a matter of years. 303 00:32:54,760 --> 00:32:58,240 And it's happened a lot in Australia's grasslands. 304 00:33:11,280 --> 00:33:15,840 This is Mount Rothwell Research Centre in Victoria. 305 00:33:17,040 --> 00:33:21,840 It's 400 hectares of high-security grassland. 306 00:33:27,280 --> 00:33:31,320 Scientists here are trying to restore animal relationships 307 00:33:31,320 --> 00:33:34,360 and thus mend a broken ecosystem. 308 00:33:40,320 --> 00:33:43,880 It's surrounded by 11 kilometres of fencing. 309 00:33:46,680 --> 00:33:50,920 7,500 volts protect the perimeter... 310 00:33:56,960 --> 00:33:59,520 ..and it's patrolled every day. 311 00:34:04,640 --> 00:34:07,240 I'm feeling a little imprisoned. 312 00:34:07,240 --> 00:34:10,120 But then, this fence is not designed to keep things in. 313 00:34:10,120 --> 00:34:13,120 It's actually designed to keep things out. 314 00:34:13,120 --> 00:34:15,400 You see, in here 315 00:34:15,400 --> 00:34:20,720 is the largest piece of native Australian grassland left in this region, 316 00:34:20,720 --> 00:34:22,920 and this fence is helping keep out 317 00:34:22,920 --> 00:34:26,680 a whole load of animals that they don't want in here. 318 00:34:26,680 --> 00:34:28,640 CAT MIAOWS 319 00:34:29,800 --> 00:34:33,680 This moggy is, or was, someone's pet, 320 00:34:33,680 --> 00:34:38,720 but she's also an alien predator that didn't evolve in this ecosystem. 321 00:34:40,640 --> 00:34:42,360 CAT MIAOWS 322 00:34:42,360 --> 00:34:47,080 You see, Australia has no native cats of any kind. 323 00:34:47,080 --> 00:34:50,720 Down under, she's an unstoppable killer 324 00:34:50,720 --> 00:34:53,560 along with feral dogs and foxes. 325 00:34:59,880 --> 00:35:05,760 These carnivores would do anything to get their jaws and claws on what's in here. 326 00:35:16,800 --> 00:35:19,400 This is a brush-tailed rock wallaby. 327 00:35:21,480 --> 00:35:23,640 And because of these introduced predators, 328 00:35:23,640 --> 00:35:27,240 he is now one of the rarest mammals in the world, 329 00:35:27,240 --> 00:35:31,360 and the extinction of just a few key creatures like him 330 00:35:31,360 --> 00:35:33,960 has had a catastrophic impact. 331 00:35:34,840 --> 00:35:38,640 Crucial ecological relationships are in tatters here, 332 00:35:38,640 --> 00:35:41,760 and as a result, this native grassland 333 00:35:41,760 --> 00:35:46,000 is now far more endangered than any tropical rainforest. 334 00:35:46,000 --> 00:35:50,640 The question is, if you remove all of the alien animals 335 00:35:50,640 --> 00:35:53,240 and reintroduce the key native ones, 336 00:35:53,240 --> 00:35:58,160 could Australia's grasslands be brought back to life? 337 00:35:58,160 --> 00:35:59,840 On the inside of this fence, 338 00:35:59,840 --> 00:36:03,960 a relatively small community of animals and plants has been saved, 339 00:36:03,960 --> 00:36:08,160 and I've got to say, some of them really are pretty odd, 340 00:36:08,160 --> 00:36:10,560 and to stand any chance of seeing them, 341 00:36:10,560 --> 00:36:12,760 I'm going to have to wait until after dark. 342 00:36:14,200 --> 00:36:16,240 INSECTS DRONE 343 00:36:33,640 --> 00:36:37,600 Welcome to the weird world of the native Aussie night. 344 00:36:59,320 --> 00:37:03,360 This is a southern brown bandicoot... 345 00:37:04,920 --> 00:37:06,560 ..and I'm getting a superb view of it. 346 00:37:06,560 --> 00:37:12,280 I'm so close that I can actually see the saliva glistening in its mouth 347 00:37:12,280 --> 00:37:14,320 as it's chewing its food. 348 00:37:16,080 --> 00:37:19,000 It's one of about 20 different species of bandicoot, 349 00:37:19,000 --> 00:37:24,680 and they all come equipped with this long, pointed and sensitive snout. 350 00:37:26,240 --> 00:37:30,000 And they're principally insectivores, meat eaters, 351 00:37:30,000 --> 00:37:33,080 but they do play a very important role 352 00:37:33,080 --> 00:37:38,120 when it comes to maintaining the plant community in this ecosystem. 353 00:37:38,120 --> 00:37:42,360 He spends all of his time digging for food. 354 00:37:43,600 --> 00:37:47,040 By the end of the night, he'll have covered the grassland 355 00:37:47,040 --> 00:37:49,440 with lots of snout-shaped conical pits. 356 00:37:51,240 --> 00:37:54,280 Here's one of the pits, here. 357 00:37:54,280 --> 00:37:58,120 And when the wind blows, grass seeds are caught in here 358 00:37:58,120 --> 00:38:03,720 along with a lot of other detritus, all of which is rich in nitrogen. 359 00:38:03,720 --> 00:38:08,160 So they become a perfect place for germination. 360 00:38:28,160 --> 00:38:33,200 This is a bettong, otherwise known as a rat kangaroo. 361 00:38:33,200 --> 00:38:35,000 They're herbivores. 362 00:38:35,000 --> 00:38:37,320 At the moment, if you listen carefully, 363 00:38:37,320 --> 00:38:41,080 you can hear it munching on some roots or tubers that it's eating. 364 00:38:47,360 --> 00:38:50,680 All of these animals are so tame 365 00:38:50,680 --> 00:38:56,160 that's it's no wonder foreign cats and foxes have almost wiped them out. 366 00:38:58,640 --> 00:39:03,400 As it feeds, it effectively ploughs this hard soil, 367 00:39:03,400 --> 00:39:05,920 allowing air and water in, 368 00:39:05,920 --> 00:39:08,280 vital for the plants that live here. 369 00:39:13,000 --> 00:39:17,240 But so that the herbivores don't do too much damage, 370 00:39:17,240 --> 00:39:21,440 this miniature Serengeti also has its own mini lion. 371 00:39:22,600 --> 00:39:24,640 SNIFFING 372 00:39:44,080 --> 00:39:46,480 This is an eastern quoll... 373 00:39:47,880 --> 00:39:50,560 ..a pocket-sized marsupial predator. 374 00:39:52,760 --> 00:39:55,040 Don't be fooled by his size. 375 00:39:55,040 --> 00:39:59,080 He can take prey much larger than himself. 376 00:39:59,080 --> 00:40:02,960 What's important is that unlike cats and foxes, 377 00:40:02,960 --> 00:40:06,320 quolls have co-evolved with their prey 378 00:40:06,320 --> 00:40:09,640 so they are a critical part of this ecosystem. 379 00:40:15,520 --> 00:40:17,680 The Rothwell experiment is working. 380 00:40:17,680 --> 00:40:23,240 Rare species of plants, birds and mammals, the entire grassland, 381 00:40:23,240 --> 00:40:25,240 is making a comeback here. 382 00:40:32,440 --> 00:40:38,280 The secret to healthy grasslands is having the right species in the right place... 383 00:40:40,600 --> 00:40:46,400 ..and there's one animal that benefits grasslands more than any other on Earth. 384 00:40:56,160 --> 00:41:00,520 These monoliths dominate the cerrado in South America. 385 00:41:00,520 --> 00:41:05,440 There can be as many as 40,000 in one square kilometre. 386 00:41:09,920 --> 00:41:14,840 From the outside, these things appear entirely lifeless. 387 00:41:14,840 --> 00:41:21,040 In fact, you could sit down here alongside one and see nothing move all day. 388 00:41:21,040 --> 00:41:23,160 But living on the inside 389 00:41:23,160 --> 00:41:28,040 is perhaps the most important animal in this entire ecosystem. 390 00:41:32,120 --> 00:41:37,280 They are grasslands' secret weapon in the battle for nitrogen. 391 00:41:44,200 --> 00:41:49,600 Termites, half-blind distant cousins of cockroaches. 392 00:41:52,320 --> 00:41:55,840 There are so many millions living in this grassland 393 00:41:55,840 --> 00:41:58,520 that their combined weight is far greater 394 00:41:58,520 --> 00:42:02,760 than that of all of the mammals living here put together. 395 00:42:04,840 --> 00:42:08,880 And yet you would have no idea they were even here 396 00:42:08,880 --> 00:42:11,080 if they didn't build these huge mounds. 397 00:42:14,720 --> 00:42:17,240 They build them as cooling towers, 398 00:42:17,240 --> 00:42:19,840 to keep the temperature of the colony on the inside 399 00:42:19,840 --> 00:42:22,480 at an optimum 30 degrees centigrade, 400 00:42:22,480 --> 00:42:25,360 and they are remarkably efficient, 401 00:42:25,360 --> 00:42:28,760 normally accurate plus or minus a single degree. 402 00:42:29,840 --> 00:42:33,000 Not bad for a colony of primitive insects. 403 00:42:33,000 --> 00:42:36,120 But then, building these mounds all over the landscape 404 00:42:36,120 --> 00:42:38,320 is the least of their accomplishments. 405 00:42:38,320 --> 00:42:40,080 CAWING 406 00:42:43,200 --> 00:42:45,120 Because, one way or another, 407 00:42:45,120 --> 00:42:51,000 termites are fundamentally important to almost all life here. 408 00:42:59,800 --> 00:43:04,920 Especially the strangest of all, the giant anteater. 409 00:43:06,560 --> 00:43:10,520 These animals are related to armadillos and sloths. 410 00:43:10,520 --> 00:43:15,920 They're part of a group called edentates, which basically means "without teeth". 411 00:43:15,920 --> 00:43:19,960 But whilst armadillos and sloths do have rudimentary teeth, 412 00:43:19,960 --> 00:43:23,040 if you were to perform a dental examination on one of these guys, 413 00:43:23,040 --> 00:43:25,680 which would be difficult because their mouth is so small, 414 00:43:25,680 --> 00:43:28,080 you'd find no teeth at all. 415 00:43:29,920 --> 00:43:33,760 But it's not teeth he needs to unlock the termites' secret. 416 00:43:39,120 --> 00:43:40,720 If you look at its front feet, 417 00:43:40,720 --> 00:43:44,480 you can see it's got these two huge claws on each one of them, 418 00:43:44,480 --> 00:43:47,760 and they can break into just about any substrate. 419 00:43:47,760 --> 00:43:50,240 It also uses them for defence. 420 00:43:50,240 --> 00:43:52,880 It's said that if it's attacked by a larger predator, 421 00:43:52,880 --> 00:43:57,120 it will stand back on its tail and lash out with those claws. 422 00:44:01,080 --> 00:44:06,160 He uses his tongue, which is over 50cm long, 423 00:44:06,160 --> 00:44:09,320 flicking it in and out at around 150 times a minute. 424 00:44:17,280 --> 00:44:22,760 Giant anteaters eat 35,000 termites a day. 425 00:44:22,760 --> 00:44:25,200 Nevertheless, you could be forgiven for thinking 426 00:44:25,200 --> 00:44:28,840 that no matter how many they hoover up, or how quickly, 427 00:44:28,840 --> 00:44:31,240 they could never sustain an animal this size. 428 00:44:32,360 --> 00:44:34,360 But they do. 429 00:44:34,360 --> 00:44:40,080 By weight, termites are the most protein-rich food that you can find. 430 00:44:40,080 --> 00:44:43,040 There's more protein in these little insects 431 00:44:43,040 --> 00:44:47,960 than there is in beans, nuts, cheese, chicken, even roast beef. 432 00:44:47,960 --> 00:44:53,240 And what's interesting is that termites occur in ecosystems all over the world, 433 00:44:53,240 --> 00:44:57,080 and wherever they do, there are creatures like this 434 00:44:57,080 --> 00:45:01,320 that have evolved to feed exclusively on termites. 435 00:45:10,880 --> 00:45:13,720 The reason termites are so rich in protein 436 00:45:13,720 --> 00:45:18,160 is all down to some very intimate relationships. 437 00:45:19,280 --> 00:45:22,400 The first is with a fungus. 438 00:45:22,400 --> 00:45:24,200 Deep within the mound, 439 00:45:24,200 --> 00:45:29,560 the fungus breaks down dead grass so the termites can digest it. 440 00:45:29,560 --> 00:45:33,520 Not much else could eke a living out of this stuff. 441 00:45:42,120 --> 00:45:45,760 The second is more remarkable still. 442 00:45:45,760 --> 00:45:50,400 You see, termites can obtain nitrogen 443 00:45:50,400 --> 00:45:52,080 directly from the air. 444 00:45:54,960 --> 00:45:57,760 And they achieve this through another symbiotic relationship, 445 00:45:57,760 --> 00:46:00,600 an even more intimate one. 446 00:46:00,600 --> 00:46:03,720 Because living inside their digestive systems 447 00:46:03,720 --> 00:46:06,560 are amazing nitrogen-trapping bacteria, 448 00:46:06,560 --> 00:46:11,520 and it's this that gives termites their special powers. 449 00:46:11,520 --> 00:46:14,040 So using the nitrogen they get from that bacteria, 450 00:46:14,040 --> 00:46:16,080 the nutrients they get from the fungus, 451 00:46:16,080 --> 00:46:17,680 they're able to turn 452 00:46:18,880 --> 00:46:24,640 this dead, woody material into a productive food source. 453 00:46:24,640 --> 00:46:29,320 This stuff, which is so low in nitrogen, so low in protein, 454 00:46:29,320 --> 00:46:31,720 they can turn into edible protein, 455 00:46:31,720 --> 00:46:35,960 and that's how they can form these vast colonies. 456 00:46:38,840 --> 00:46:42,520 The termite mound becomes a nitrogen hot spot. 457 00:46:42,520 --> 00:46:45,480 That's good for anteaters 458 00:46:45,480 --> 00:46:51,400 but also for all the surrounding plants and for all the other animals living here. 459 00:47:03,600 --> 00:47:09,520 The incredible actions of termites nurture grasslands all over the world... 460 00:47:11,960 --> 00:47:15,600 ..including Kenya's whistling acacia savannah. 461 00:47:32,280 --> 00:47:36,120 Here, the impact of termites goes right to the top... 462 00:47:38,560 --> 00:47:42,080 ..all the way to the world's tallest land animal. 463 00:48:07,200 --> 00:48:11,520 When I was a child, we thought there was just one type of giraffe, 464 00:48:11,520 --> 00:48:14,560 but now we know there are six different species. 465 00:48:16,720 --> 00:48:19,440 This one's a reticulated giraffe. 466 00:48:31,840 --> 00:48:33,800 He can reach anything, 467 00:48:33,800 --> 00:48:39,440 but of all the plants here, he's chosen to eat the whistling acacia tree. 468 00:48:44,280 --> 00:48:45,760 But just look at it. 469 00:48:45,760 --> 00:48:48,800 It's one of the best-defended plants in the whole of Africa. 470 00:49:06,960 --> 00:49:11,400 But why are these trees so well armed 471 00:49:11,400 --> 00:49:15,080 against browsing animals like these giraffes? 472 00:49:15,080 --> 00:49:20,400 Well, the answer, you won't be surprised, comes down to nitrogen. 473 00:49:20,400 --> 00:49:25,960 You see, these trees' leaves are absolutely packed with nitrogen. 474 00:49:27,440 --> 00:49:31,880 That's why they are the botanical equivalent of Fort Knox. 475 00:49:33,920 --> 00:49:37,800 At the base of many of these acacias are colonies of African termites. 476 00:49:39,000 --> 00:49:41,840 The acacias' roots are boring under the mounds, 477 00:49:41,840 --> 00:49:45,520 tapping into a rich well of nitrogen. 478 00:49:45,520 --> 00:49:50,560 As a result, these acacias become an oasis in a nitrogen desert. 479 00:49:52,360 --> 00:49:54,240 So it's really no wonder 480 00:49:54,240 --> 00:49:58,080 that the thorns alone don't deter giraffes from tucking in. 481 00:50:00,640 --> 00:50:05,600 So, not to be beaten, the tree employs another line of defence, 482 00:50:05,600 --> 00:50:07,880 its own private army. 483 00:50:10,240 --> 00:50:11,800 Now, just watch this. 484 00:50:11,800 --> 00:50:16,800 I'm going to pretend to be a giraffe browsing on this branch here. 485 00:50:16,800 --> 00:50:20,920 So I'm going to pull at the leaves, shake it about a bit, 486 00:50:20,920 --> 00:50:25,080 try and not get jabbed by the thorns here. 487 00:50:25,080 --> 00:50:26,800 But just look at this. 488 00:50:26,800 --> 00:50:28,840 Very quickly, 489 00:50:28,840 --> 00:50:35,880 a whole mass of these Crematogaster ants swarms out and covers my hand. 490 00:50:35,880 --> 00:50:38,520 And I can tell you that, if you were a giraffe browsing on this, 491 00:50:38,520 --> 00:50:42,760 you wouldn't want these things all over your tongue. 492 00:50:44,000 --> 00:50:46,840 Each ant is armed with a chemical weapon. 493 00:50:46,840 --> 00:50:49,320 It's capable of squirting venom. 494 00:50:51,280 --> 00:50:55,200 Each gall houses a separate colony of ants, 495 00:50:55,200 --> 00:50:58,840 and each branch might have a dozen or more of these galls. 496 00:51:08,800 --> 00:51:12,640 So the only way a giraffe can get an ant-free meal 497 00:51:12,640 --> 00:51:15,880 is to grab a quick snack and then move on. 498 00:51:33,680 --> 00:51:36,640 The tree has evolved to produce these hollow thorns, 499 00:51:36,640 --> 00:51:42,120 and they are the perfect structures for the ants to make their colonies inside. 500 00:51:42,120 --> 00:51:45,560 And in return for the plant's investment, 501 00:51:45,560 --> 00:51:49,000 it gets these insects as vigorous defenders. 502 00:51:58,360 --> 00:52:04,000 But this is just the beginning of a truly amazing web of relationships. 503 00:52:13,560 --> 00:52:16,040 These are patas monkeys. 504 00:52:25,000 --> 00:52:30,640 As grassland specialists, they're the fastest-running primates in the world. 505 00:52:30,640 --> 00:52:35,480 In the 100-metre sprint, they'd beat any Olympian by three seconds. 506 00:52:46,680 --> 00:52:49,560 To fuel their energetic lifestyles, 507 00:52:49,560 --> 00:52:53,960 their favourite food is Crematogaster ants and their larvae. 508 00:53:00,040 --> 00:53:04,000 The trick is finding them in just the right position. 509 00:53:08,240 --> 00:53:11,200 He could easily have his eye out on those thorns. 510 00:53:53,200 --> 00:53:56,840 Once ripped open, the ants abandon the gall, 511 00:53:56,840 --> 00:54:02,840 but this act of primate vandalism only serves to enrich this mini ecosystem. 512 00:54:05,840 --> 00:54:10,680 You see, a short while later, a new occupant has moved in. 513 00:54:17,280 --> 00:54:20,920 Here, protected from predators and the harsh sun, 514 00:54:20,920 --> 00:54:24,440 a dwarf gecko has laid two eggs. 515 00:54:34,160 --> 00:54:39,600 Because she isn't a threat to either them or the acacia, the ants mostly ignore her. 516 00:54:47,360 --> 00:54:52,040 After four months, a perfect miniature gecko hatches out. 517 00:55:04,240 --> 00:55:06,640 It's completely defenceless, 518 00:55:06,640 --> 00:55:12,320 but luckily, it's found itself in the perfect nest. 519 00:55:17,720 --> 00:55:23,480 It couldn't possibly appreciate all of the creatures here on the grassland 520 00:55:23,480 --> 00:55:27,560 that have come together to put a safe roof over its head. 521 00:55:35,360 --> 00:55:37,640 The giraffe eats the acacia tree, 522 00:55:37,640 --> 00:55:42,800 so it continually produces those galls which form the geckos' home. 523 00:55:42,800 --> 00:55:46,880 The acacia tree needs the ants to protect its leaves and keep it healthy, 524 00:55:46,880 --> 00:55:52,720 and in turn, the patas monkey needs those ants and their larvae as food. 525 00:55:52,720 --> 00:55:55,600 And all of this can only happen 526 00:55:55,600 --> 00:55:58,840 because the tree has managed to accumulate nitrogen 527 00:55:58,840 --> 00:56:02,520 from a grassland that's evolved to prosper 528 00:56:02,520 --> 00:56:07,560 despite the fact that this element is always in short supply. 529 00:56:13,480 --> 00:56:20,200 It's often said that you can only tell who your real friends are in times of need. 530 00:56:22,200 --> 00:56:24,600 This is also true in nature. 531 00:56:27,720 --> 00:56:33,040 You might ask if it really matters if an animal becomes extinct. 532 00:56:36,000 --> 00:56:40,280 Well, so intricate are the connections in the natural world 533 00:56:40,280 --> 00:56:44,520 that there's no way to predict the impact of adding or removing species 534 00:56:44,520 --> 00:56:46,560 until it's too late. 535 00:56:55,360 --> 00:56:59,600 Who would have thought that a bettong would need a bandicoot, 536 00:56:59,600 --> 00:57:03,000 that a leaf-cutter ant would need a maned wolf, 537 00:57:03,000 --> 00:57:07,920 or, indeed, that a gecko would need a giraffe? 538 00:57:07,920 --> 00:57:13,160 Now, the complex web of relationships that we've seen 539 00:57:13,160 --> 00:57:15,320 have evolved over millions of years, 540 00:57:15,320 --> 00:57:19,320 but we've only scratched the surface of a myriad of stories 541 00:57:19,320 --> 00:57:26,000 that, when they come together, make these grasslands functional ecosystems, 542 00:57:26,000 --> 00:57:31,520 and it's here that I've learned to see the real beauty in nature. 543 00:57:31,520 --> 00:57:35,720 You see, for me, it's not in the minute detail. 544 00:57:35,720 --> 00:57:38,200 It's in the bigger picture. 545 00:57:38,200 --> 00:57:43,960 Because this works perfectly, and that is beautiful. 546 00:58:02,320 --> 00:58:06,920 If you'd like to know more about the fascinating web of links between species, 547 00:58:06,920 --> 00:58:12,480 the Open University has produced some material both to inform and inspire you. 548 00:58:12,480 --> 00:58:14,240 For your free copy, 549 00:58:14,240 --> 00:58:17,240 or to find out more about Open University programmes, ring: 550 00:58:22,160 --> 00:58:23,520 Or go to the website: 551 00:58:27,240 --> 00:58:29,720 And then follow the links to Open University. 552 00:58:30,840 --> 00:58:33,320 And join me next time, 553 00:58:33,320 --> 00:58:36,960 when I'll be travelling to the world's greatest seasonal forest.