1 00:00:06,542 --> 00:00:09,500 DAVID ATTENBOROUGH: The power of the sun drives the seasons, 2 00:00:09,582 --> 00:00:11,538 transforming our planet. 3 00:00:13,102 --> 00:00:16,458 Vast movements of ocean and air currents 4 00:00:16,542 --> 00:00:19,261 bring dramatic change throughout the year. 5 00:00:23,822 --> 00:00:27,861 And in a few special places, these seasonal changes 6 00:00:27,942 --> 00:00:32,220 create some of the greatest wildlife spectacles on Earth. 7 00:00:34,822 --> 00:00:37,382 One of the most remarkable transformations 8 00:00:37,462 --> 00:00:42,490 occurs here in Southern Africa, in the desert lands of the Kalahari. 9 00:00:44,182 --> 00:00:49,176 Large herds of animals trek for months in search of food and water, 10 00:00:49,262 --> 00:00:53,494 waiting for an event that will dramatically change their lives. 11 00:00:54,582 --> 00:01:00,452 For once a year, life-giving water turns an area of unforgiving desert 12 00:01:01,022 --> 00:01:06,142 into a vast, watery paradise known as the Okavango. 13 00:01:19,582 --> 00:01:22,176 Where and when the Okavango will flood 14 00:01:22,262 --> 00:01:25,174 determines the fate of millions of animals, 15 00:01:26,182 --> 00:01:29,777 making this one of nature's truly great events. 16 00:01:55,782 --> 00:02:00,014 In the heart of Southern Africa, the desert lands of the Kalahari 17 00:02:00,102 --> 00:02:04,015 cover an area of almost 400,000 square miles. 18 00:02:06,142 --> 00:02:09,054 It's one of driest places on Earth, 19 00:02:09,142 --> 00:02:14,341 yet miraculously, great herds of grazing animals survive here. 20 00:02:17,182 --> 00:02:19,616 They lead a nomadic existence, 21 00:02:19,702 --> 00:02:24,059 trekking huge distances in search of food and water. 22 00:02:35,142 --> 00:02:39,897 It's the start of the dry season. It won't rain for eight months, 23 00:02:39,982 --> 00:02:44,772 and so life, already hard, is about to get even harder. 24 00:02:56,942 --> 00:02:58,614 Of all the animals here, 25 00:02:58,702 --> 00:03:01,694 perhaps the most resourceful are the elephants. 26 00:03:05,142 --> 00:03:09,294 Each family is led by an older female, the matriarch, 27 00:03:09,382 --> 00:03:13,660 and they all rely on her experience to guide them through the desert. 28 00:03:21,542 --> 00:03:25,854 Her years here have taught this matriarch that, one day, 29 00:03:25,942 --> 00:03:30,572 hundreds of miles to the west, she will find a lush grassland. 30 00:03:32,542 --> 00:03:34,453 But before she will find it, 31 00:03:34,542 --> 00:03:38,171 her family will have to survive many months in the desert. 32 00:03:41,822 --> 00:03:44,700 The water that could transform their lives 33 00:03:44,782 --> 00:03:47,660 has its origins a thousand miles away, 34 00:03:47,742 --> 00:03:51,098 in the rain clouds over the highlands of Angola. 35 00:03:51,182 --> 00:03:52,376 (THUNDER CRASHES) 36 00:04:05,542 --> 00:04:10,775 The rain is so plentiful it has the power to transform a desert. 37 00:04:13,622 --> 00:04:19,174 It cascades southwards, not to the sea, but into the heart of the Kalahari, 38 00:04:19,742 --> 00:04:22,540 towards a basin shaped like a hand 39 00:04:22,622 --> 00:04:24,931 known as the Okavango. 40 00:04:30,502 --> 00:04:34,097 Here it will fill the swamp that lies at its entrance. 41 00:04:35,542 --> 00:04:38,295 And only if the rains have been plentiful 42 00:04:38,382 --> 00:04:41,738 will water flood out onto the arid plains beyond, 43 00:04:41,822 --> 00:04:44,734 transforming them into the grassland paradise 44 00:04:44,822 --> 00:04:47,017 that the herds so badly need. 45 00:04:55,222 --> 00:04:59,818 Out in the desert, the elephants need to find water every three days. 46 00:05:02,182 --> 00:05:05,492 Thirsty elephants often race into pools, 47 00:05:05,582 --> 00:05:09,495 but the matriarch knows that her family must not rush in. 48 00:05:15,222 --> 00:05:17,213 This pool is stagnant, 49 00:05:17,302 --> 00:05:20,453 and the elephants have a trick that deals with that. 50 00:05:25,982 --> 00:05:28,052 Sediment settles to the bottom, 51 00:05:28,142 --> 00:05:31,532 and the cleaner, fresher water lies on the surface. 52 00:05:35,942 --> 00:05:38,456 They skim it carefully from the top. 53 00:05:50,102 --> 00:05:55,130 Then, as gently as elephants can, they move forward slowly, 54 00:05:55,222 --> 00:05:58,055 trying not to disturb the stagnant layers. 55 00:06:17,262 --> 00:06:22,131 But precious water like this draws in herds from far and wide. 56 00:06:29,142 --> 00:06:34,739 In the exuberance of a greeting all their careful work is undone. 57 00:06:44,302 --> 00:06:48,056 When bulls are forced together by the need for water, 58 00:06:48,142 --> 00:06:49,973 tempers can flare. 59 00:07:24,902 --> 00:07:29,817 At this time of year, food and water can often be far apart. 60 00:07:32,502 --> 00:07:35,858 And so, now that the little ones are refreshed, 61 00:07:35,942 --> 00:07:38,820 the family has to head off to find food. 62 00:07:50,782 --> 00:07:55,572 The distant Okavango plains that they're heading for are still dry, 63 00:07:55,662 --> 00:07:57,653 and getting even drier. 64 00:08:04,182 --> 00:08:07,811 Trapped catfish struggle in a shrinking pool. 65 00:08:21,462 --> 00:08:24,977 And the burning sun is not their only enemy. 66 00:08:27,542 --> 00:08:29,180 (CAWING) 67 00:08:31,902 --> 00:08:36,612 An opportunity like this attracts eagles from many miles away. 68 00:08:39,982 --> 00:08:44,373 Usually, they dive and snatch fish from the surface of the water, 69 00:08:44,462 --> 00:08:47,852 but in this drought they won't have to work so hard. 70 00:08:53,182 --> 00:08:55,377 These are prized catches. 71 00:09:05,902 --> 00:09:09,372 Marabou storks and jackals muscle in on the leftovers. 72 00:09:14,662 --> 00:09:17,540 But even with this bounty of fish, 73 00:09:17,622 --> 00:09:22,332 it's in an eagle's nature to steal a meal rather than catch its own. 74 00:09:51,462 --> 00:09:55,535 And all this squabbling gives the marabou a chance. 75 00:10:05,102 --> 00:10:06,421 Got it! 76 00:10:09,582 --> 00:10:13,860 Only the return of the flood can save these fish now. 77 00:10:15,942 --> 00:10:17,580 All around these pools, 78 00:10:17,662 --> 00:10:21,974 the grass on the Okavango plains continues to wither and die. 79 00:10:27,022 --> 00:10:29,741 But there's still some nourishment left in the leaves, 80 00:10:29,822 --> 00:10:34,338 and millions of tiny mouths make the most of what remains. 81 00:10:39,982 --> 00:10:43,861 Termites chop the dead grass and drag it underground 82 00:10:43,942 --> 00:10:45,534 to feed their colony. 83 00:10:49,262 --> 00:10:51,139 They play a crucial role, 84 00:10:51,222 --> 00:10:54,737 helping to return nutrients to these poor soils. 85 00:10:54,822 --> 00:10:57,973 But now, taking the last, precious grass, 86 00:10:58,062 --> 00:11:01,179 they leave dust and sand in its place. 87 00:11:09,742 --> 00:11:13,257 With the grazing animals dispersed far and wide, 88 00:11:13,342 --> 00:11:16,061 it's leaner times for predators here. 89 00:11:30,502 --> 00:11:34,415 Only a desperate leopard would tackle a porcupine. 90 00:11:40,182 --> 00:11:44,016 This youngster is about to meet double trouble. 91 00:11:47,382 --> 00:11:51,057 The only place to get a bite is on their undersides. 92 00:11:52,782 --> 00:11:56,457 But the porcupines work together to watch each others' backs. 93 00:12:08,662 --> 00:12:10,732 The leopard will have to flip one over. 94 00:12:17,462 --> 00:12:21,933 Pin-sharp quills can easily snap off and become embedded in flesh. 95 00:12:38,222 --> 00:12:42,818 It's a highly effective defence that can also be turned into attack. 96 00:12:59,862 --> 00:13:01,659 It's a harsh lesson, 97 00:13:01,742 --> 00:13:06,020 but with luck and a bit of healing time, there'll be no lasting damage. 98 00:13:13,222 --> 00:13:14,780 Two hundred miles away, 99 00:13:14,862 --> 00:13:19,140 the pulse of life-giving water has now reached the swampland 100 00:13:19,222 --> 00:13:21,531 at the entrance to the Okavango. 101 00:13:23,062 --> 00:13:26,293 Here, thick beds of papyrus act like a sponge, 102 00:13:26,382 --> 00:13:28,338 slowing the water's progress. 103 00:13:30,022 --> 00:13:32,411 The swamp can take months to fill, 104 00:13:32,502 --> 00:13:34,970 and only then, if there is enough water, 105 00:13:35,062 --> 00:13:40,295 can it overflow and rejuvenate the plains on which the herds depend. 106 00:13:47,822 --> 00:13:49,175 Far to the east, 107 00:13:49,262 --> 00:13:53,494 the matriarch elephants have led their families to desert woodlands. 108 00:13:58,502 --> 00:14:02,859 It seems an odd place to come - there's no sign of food 109 00:14:03,462 --> 00:14:05,817 and there's little shade for the calves. 110 00:14:09,462 --> 00:14:12,579 But elephants can do something unusual. 111 00:14:16,902 --> 00:14:21,339 They can eat and digest seemingly lifeless branches. 112 00:14:33,262 --> 00:14:37,414 The youngsters need to learn that dry sticks are nutritious, 113 00:14:39,502 --> 00:14:42,699 and that there is moisture in the bark. 114 00:14:46,622 --> 00:14:49,739 But bark won't feed the youngest calves. 115 00:14:49,822 --> 00:14:52,859 They need to drink 1 5 litres of milk a day, 116 00:14:54,142 --> 00:14:58,055 so their mothers desperately need water as well as food. 117 00:15:01,942 --> 00:15:05,332 Exhaustion has got the better of one young female. 118 00:15:11,182 --> 00:15:14,174 But she won't get the chance to rest for long. 119 00:15:15,182 --> 00:15:17,696 The next waterhole could be 30 miles away, 120 00:15:17,782 --> 00:15:20,854 and the whole herd needs to get moving. 121 00:15:34,782 --> 00:15:37,012 Back on the Okavango plains, 122 00:15:37,102 --> 00:15:40,253 the last remnants of grass are going up in smoke. 123 00:15:47,902 --> 00:15:51,417 It's bad news for the few grazers that remain. 124 00:16:05,142 --> 00:16:08,851 A few birds collect the escaping insects. 125 00:16:13,782 --> 00:16:17,900 But fires don't help those who need to eat grass here and now. 126 00:16:33,422 --> 00:16:36,732 The Okavango plains are at their most desolate. 127 00:16:37,222 --> 00:16:39,019 Yet, out in the desert, 128 00:16:39,102 --> 00:16:42,299 the elephant herds are heading towards them. 129 00:16:50,182 --> 00:16:54,494 The matriarchs guide their families along the maze of trails 130 00:16:54,582 --> 00:16:56,220 to the next waterhole. 131 00:17:04,302 --> 00:17:07,180 And this time there's no hanging about. 132 00:17:24,942 --> 00:17:27,217 It soon turns into a mud bath. 133 00:17:30,862 --> 00:17:34,172 But elephants have a use for the mud, too, 134 00:17:34,262 --> 00:17:39,700 for mud acts both as a sunscreen and an insect repellent. 135 00:17:52,742 --> 00:17:56,655 Buffalo have learned to follow the elephant trails to water. 136 00:18:05,142 --> 00:18:07,656 There is a clear pecking order here. 137 00:18:08,942 --> 00:18:12,139 Elephants take priority, 138 00:18:12,222 --> 00:18:14,690 and zebra are the last in the line. 139 00:18:26,342 --> 00:18:28,014 (SNUFFLING) 140 00:18:28,102 --> 00:18:30,662 Even when young bulls have drunk their fill, 141 00:18:30,742 --> 00:18:32,972 they still torment the buffalo. 142 00:18:36,342 --> 00:18:39,459 And they definitely know which end to aim for. 143 00:18:51,262 --> 00:18:55,016 By the time the herds face their final trek across open desert, 144 00:18:55,102 --> 00:18:56,854 the swamp has filled. 145 00:19:01,302 --> 00:19:04,339 The channels which lead out onto the parched plains 146 00:19:04,422 --> 00:19:07,016 get their first, welcome trickle of water. 147 00:19:16,102 --> 00:19:19,492 Amazingly, when the plains are at their driest, 148 00:19:19,582 --> 00:19:24,895 fresh water from a distant land spills into the parched river beds. 149 00:19:28,622 --> 00:19:31,216 First it fills the dry channels, 150 00:19:31,302 --> 00:19:35,011 leaving the baked plains on either side hard and dry. 151 00:19:54,702 --> 00:19:58,854 All along the route it finds empty pools to fill. 152 00:20:01,942 --> 00:20:05,651 And now, these pools become magnets for birds, 153 00:20:05,742 --> 00:20:08,814 which flock here from the surrounding desert lands. 154 00:20:14,342 --> 00:20:17,573 Red-billed quelea can now collect those grass seeds 155 00:20:17,662 --> 00:20:19,493 that the termites have missed. 156 00:20:40,062 --> 00:20:43,418 For most of the year, the quelea are nomadic, 157 00:20:43,502 --> 00:20:46,016 and it's this freedom to follow the water 158 00:20:46,102 --> 00:20:50,493 that helps make quelea one of the most numerous birds on Earth. 159 00:21:08,902 --> 00:21:11,211 As the water fills the Okavango, 160 00:21:11,302 --> 00:21:14,453 animals that have survived in shrinking waterholes 161 00:21:14,542 --> 00:21:16,419 begin to move in. 162 00:21:18,222 --> 00:21:21,419 Female hippos gather in the best territories. 163 00:21:22,342 --> 00:21:25,334 And this male is prepared to fight for one. 164 00:21:34,582 --> 00:21:38,052 Only a dominant bull will mate with the females, 165 00:21:38,142 --> 00:21:41,293 and the current chieftain isn't prepared to give way. 166 00:21:42,782 --> 00:21:44,010 (GRUNTS) 167 00:21:49,342 --> 00:21:51,412 The intimidation begins. 168 00:22:01,662 --> 00:22:05,814 When neither backs down, there can be only one outcome. 169 00:22:20,462 --> 00:22:25,092 Fights can go on for hours and can be to the death. 170 00:22:32,022 --> 00:22:37,050 Forward-pointing tusks can stab right through protective blubber. 171 00:23:14,342 --> 00:23:19,416 This savage bite to the head brings the contest to an end. 172 00:23:31,062 --> 00:23:35,931 The incumbent has re-established his right to mate with the females, 173 00:23:36,622 --> 00:23:38,852 and he wastes no time. 174 00:23:44,022 --> 00:23:46,331 This is a prime territory, 175 00:23:46,422 --> 00:23:50,859 and he will face many more challenges if he is to continue to hold it. 176 00:23:59,142 --> 00:24:01,451 The loser is badly injured. 177 00:24:04,462 --> 00:24:07,659 Hippos can die from infected wounds, 178 00:24:07,742 --> 00:24:11,132 but this young male is fit and should survive. 179 00:24:16,102 --> 00:24:18,855 Ox-peckers are a mixed blessing. 180 00:24:18,942 --> 00:24:22,696 They keep his wounds clean, but they also keep them open. 181 00:24:35,502 --> 00:24:39,654 Fresh water continues to pump through the Okavango plains, 182 00:24:39,742 --> 00:24:42,017 bringing life wherever it flows. 183 00:24:43,902 --> 00:24:48,612 But out in the Kalahari, water is now almost impossible to find. 184 00:24:55,382 --> 00:24:58,692 A matriarch has led her family many miles, 185 00:24:58,782 --> 00:25:01,615 only to find the waterhole empty. 186 00:25:06,702 --> 00:25:09,774 This year the drought is gripping hard. 187 00:25:13,502 --> 00:25:16,858 Each matriarch encourages her family onward. 188 00:25:19,022 --> 00:25:21,934 The calves' lives depend on her. 189 00:25:27,902 --> 00:25:30,700 And with pools so scarce now, 190 00:25:30,782 --> 00:25:34,695 even when she finds water, they won't be drinking alone. 191 00:25:43,342 --> 00:25:48,814 At this time of year, some lion prides base themselves around waterholes, 192 00:25:50,662 --> 00:25:53,415 and they're always on the lookout for a meal. 193 00:26:03,462 --> 00:26:08,217 But the elephants' desperate need to drink outweighs the risk. 194 00:26:14,062 --> 00:26:17,896 The mothers are producing less milk, and the calves are weak. 195 00:26:24,142 --> 00:26:27,293 The adults try to shield them from watchful eyes. 196 00:26:30,422 --> 00:26:33,061 It's an uneasy stand-off. 197 00:26:38,862 --> 00:26:42,411 In daylight, the elephants should have nothing to fear. 198 00:26:51,902 --> 00:26:57,056 The lions creep as close as they dare, as they too try to drink. 199 00:27:08,862 --> 00:27:13,094 One mistake from an elephant and the lions could attack. 200 00:27:16,182 --> 00:27:19,777 Big cats keep tired elephants on their toes. 201 00:27:20,942 --> 00:27:22,136 (TRUMPETING) 202 00:27:27,582 --> 00:27:30,619 While the desert experiences the peak of the drought, 203 00:27:30,702 --> 00:27:33,694 the meandering network of channels in the Okavango 204 00:27:33,782 --> 00:27:35,693 is finally brimful. 205 00:27:37,822 --> 00:27:40,382 They are ready to overflow. 206 00:27:44,142 --> 00:27:49,694 Fish gather, ready to ride the flood as a miracle begins to materialise. 207 00:27:54,502 --> 00:27:59,974 And the barrier of desert sand seems to dissolve in the magical water. 208 00:28:12,542 --> 00:28:15,261 Under cloudless Kalahari skies, 209 00:28:15,342 --> 00:28:21,019 fresh, sweet water at last begins to bathe the parched plains. 210 00:29:00,062 --> 00:29:04,817 Millions upon millions of litres surge over the banks. 211 00:29:08,982 --> 00:29:12,292 This is what the fish have been waiting for. 212 00:29:15,662 --> 00:29:18,222 New life returns. 213 00:29:40,822 --> 00:29:44,019 And as the water soaks deep into the sand, 214 00:29:44,102 --> 00:29:47,731 it stirs dormant animals into life. 215 00:29:56,542 --> 00:29:59,261 Others are more forcibly evicted. 216 00:30:03,742 --> 00:30:08,293 It's all fresh food, a banquet ready for the feasting. 217 00:30:19,742 --> 00:30:25,214 Water birds follow the advancing front, making the most of the sudden harvest. 218 00:30:47,182 --> 00:30:50,094 The plains soon teem with life. 219 00:30:53,022 --> 00:30:55,092 But not all are here to feed. 220 00:30:55,622 --> 00:30:58,056 Some have come to breed. 221 00:31:03,302 --> 00:31:05,657 No one knows where they've come from, 222 00:31:05,742 --> 00:31:08,131 but within moments of the flood's arrival, 223 00:31:08,222 --> 00:31:12,261 tens of thousands of dragonflies appear at the water's edge. 224 00:31:24,742 --> 00:31:29,532 The vivid red male leads his partner in a magical dance, 225 00:31:29,622 --> 00:31:32,216 guiding her to lay their eggs in the shallows. 226 00:32:13,502 --> 00:32:16,175 The flood spills ever onwards, 227 00:32:16,262 --> 00:32:20,414 until it finally reaches the outer fringes of the Okavango. 228 00:32:24,662 --> 00:32:28,860 The catfish, miraculously, still cling to life. 229 00:32:50,222 --> 00:32:56,331 Within moments, the life-giving power of fresh water revitalises them. 230 00:33:27,142 --> 00:33:31,021 And now, on the plains that appeared so lifeless, 231 00:33:31,102 --> 00:33:35,175 some of the most beautiful and colourful changes occur. 232 00:33:39,542 --> 00:33:43,774 Within days, fields of lilies burst into life. 233 00:33:54,182 --> 00:34:00,496 They provide pollen for the early bees, and a hiding place for reed frogs. 234 00:34:11,982 --> 00:34:17,136 And it's only now that the most crucial gift of the flood, the grass 235 00:34:17,222 --> 00:34:21,010 that the desert herds need so badly, begins to grow. 236 00:34:49,222 --> 00:34:53,500 Hippos bulldoze their way towards the sprouting grasslands, 237 00:34:53,582 --> 00:34:58,019 their paths opening up new arteries that help keep the water flowing. 238 00:35:06,182 --> 00:35:07,934 In just a few weeks, 239 00:35:08,022 --> 00:35:11,492 thousands of square miles of dry desert plains 240 00:35:11,582 --> 00:35:15,860 are turned into a watery green grassland. 241 00:35:19,902 --> 00:35:24,293 The network of hippo paths benefits all kinds of other animals, 242 00:35:24,382 --> 00:35:27,658 from predatory crocodiles to the grazing herds. 243 00:35:46,302 --> 00:35:51,854 This fresh grass is what the elephants, and indeed all the grazing animals, 244 00:35:51,942 --> 00:35:53,421 have been waiting for. 245 00:36:01,262 --> 00:36:02,854 Their pace quickens. 246 00:36:04,102 --> 00:36:08,141 For months, they have only known the dry smell of the desert. 247 00:36:10,462 --> 00:36:14,501 And now, they can catch the scent of fresh grass in the wind. 248 00:36:19,862 --> 00:36:24,652 Red lechwe are the first to take advantage of the young shoots. 249 00:37:13,462 --> 00:37:16,420 The lions are no threat here. 250 00:37:16,502 --> 00:37:21,098 They're not very fast in water, and their prey seem to know it. 251 00:37:24,782 --> 00:37:28,377 Lechwe revel in the safety the flood brings. 252 00:38:11,142 --> 00:38:15,420 Soon they will be joined by the herds of elephant and buffalo. 253 00:38:18,822 --> 00:38:22,212 And the lions seem to know they're not far away. 254 00:38:29,382 --> 00:38:32,738 Baboons don't enjoy getting their feet wet, 255 00:38:35,142 --> 00:38:40,057 but the banquet of flowers and juicy snails is just irresistible. 256 00:38:57,182 --> 00:38:59,696 But they are at their most vulnerable here 257 00:38:59,782 --> 00:39:01,693 from lurking crocodiles, 258 00:39:01,782 --> 00:39:04,250 so they keep an ever-watchful eye. 259 00:39:06,782 --> 00:39:11,856 Babies just cling on tight and hope the water doesn't get too deep. 260 00:39:16,262 --> 00:39:21,017 At their feet, the flooded plains are now a vast fish nursery, 261 00:39:21,102 --> 00:39:22,774 teeming with life. 262 00:39:27,782 --> 00:39:29,818 Predatory fish follow. 263 00:39:37,102 --> 00:39:39,821 But they too will have to be wary. 264 00:39:44,022 --> 00:39:48,777 For the Okavango now puts on one of the finest bird shows 265 00:39:48,862 --> 00:39:51,171 to be seen anywhere in the world. 266 00:40:13,262 --> 00:40:17,574 The rising waters create thousands of tiny islands. 267 00:40:18,462 --> 00:40:21,579 Safe from predators, surrounded by fish, 268 00:40:21,662 --> 00:40:24,779 these are the perfect place to raise chicks. 269 00:40:34,462 --> 00:40:37,772 This is the miracle of the Okavango. 270 00:40:40,982 --> 00:40:44,657 Once a year, it provides a magical time of plenty 271 00:40:44,742 --> 00:40:48,701 at the height of the dry season, in the middle of a desert. 272 00:40:58,942 --> 00:41:02,821 Only now, with the grasslands at their most productive, 273 00:41:02,902 --> 00:41:05,575 do the great herds arrive, 274 00:41:05,662 --> 00:41:08,620 and they've timed it to perfection. 275 00:41:11,342 --> 00:41:15,255 The herds grow larger as elephant families and buffalo 276 00:41:15,342 --> 00:41:18,015 converge from all over the desert. 277 00:41:24,662 --> 00:41:28,496 But as they all get closer to the flooded grassland, 278 00:41:28,582 --> 00:41:31,574 there is one final challenge to face. 279 00:41:49,622 --> 00:41:54,491 Lions have chosen this thick cover to lay their ambushes. 280 00:42:00,222 --> 00:42:02,736 Their favourite prey is the buffalo. 281 00:42:08,422 --> 00:42:12,654 Adult buffalo are powerful and can easily trample lions, 282 00:42:15,302 --> 00:42:20,979 so the lionesses seek out weaker calves that fall behind the herd. 283 00:42:29,222 --> 00:42:32,180 A nervous buffalo mother spots their approach 284 00:42:33,622 --> 00:42:35,419 and the herd stampedes. 285 00:42:37,742 --> 00:42:41,655 One lioness takes a gamble, moving in on a well-protected calf. 286 00:42:45,862 --> 00:42:47,932 The buffalo close ranks, 287 00:42:49,222 --> 00:42:52,498 and suddenly, the lionesses beat a hasty retreat. 288 00:43:03,662 --> 00:43:04,856 (ROARING) 289 00:43:07,622 --> 00:43:10,580 In the panic, calves are separated from their mothers. 290 00:43:13,262 --> 00:43:17,301 Amid the confusion, a lioness darts in and grabs one. 291 00:43:24,982 --> 00:43:27,860 Many buffalo will fall to lions here. 292 00:43:35,982 --> 00:43:38,337 Lions are opportunists, 293 00:43:38,422 --> 00:43:42,176 and even an unguarded elephant calf can be vulnerable. 294 00:43:54,902 --> 00:43:56,938 The elephants are nervous. 295 00:44:00,942 --> 00:44:04,491 The scent of lion is all around, yet they can't see them. 296 00:44:08,862 --> 00:44:10,534 A lioness is following them, 297 00:44:10,622 --> 00:44:13,455 trying to separate the young straggler from the herd. 298 00:44:16,222 --> 00:44:17,655 (TRUMPETING) 299 00:44:17,742 --> 00:44:21,257 One adolescent fights back, confronting its enemy. 300 00:44:36,262 --> 00:44:38,730 In a panic, the family stampedes. 301 00:44:41,702 --> 00:44:43,852 The straggler is taken. 302 00:44:58,102 --> 00:45:00,775 After months of arduous trekking, 303 00:45:00,862 --> 00:45:04,491 this elephant family has lost one of its young ones. 304 00:45:11,782 --> 00:45:16,298 But most of the elephants, at last, have made it through, 305 00:45:16,382 --> 00:45:19,021 and the great flood awaits. 306 00:45:22,142 --> 00:45:25,691 Older elephants have been here many times before, 307 00:45:25,782 --> 00:45:29,377 but the newest calves have never seen so much refreshment. 308 00:45:47,902 --> 00:45:52,976 At last, they get that first drink of sweet, fresh water. 309 00:46:25,342 --> 00:46:27,936 Thousands of buffalo and zebra 310 00:46:28,022 --> 00:46:31,981 have also made it to the magical Okavango wetlands. 311 00:46:46,862 --> 00:46:52,016 Somehow, these remarkable elephants have learned how to find a flood 312 00:46:52,102 --> 00:46:57,460 from hundreds of miles away, and to time their arrival just right. 313 00:47:02,822 --> 00:47:06,781 If it wasn't for this annual gift of precious grass, 314 00:47:06,862 --> 00:47:09,740 the herds couldn't survive the dry season 315 00:47:09,822 --> 00:47:11,813 in the surrounding Kalahari. 316 00:47:17,502 --> 00:47:21,939 This year the Great Flood has lived up to its name. 317 00:47:42,702 --> 00:47:44,579 The lives of these elephants 318 00:47:44,662 --> 00:47:49,213 are dominated by this annual rhythm of wet and dry, 319 00:47:49,302 --> 00:47:53,341 a seasonal cycle driven by the power of the sun. 320 00:48:02,902 --> 00:48:07,532 The Okavango River has no great lake to flow into, 321 00:48:07,622 --> 00:48:09,897 nor does it ever reach the sea. 322 00:48:10,662 --> 00:48:13,859 Its life-giving waters simply evaporate 323 00:48:13,942 --> 00:48:17,457 into the great emptiness of the Kalahari sky. 324 00:48:22,102 --> 00:48:26,539 In a few months, some may fall as rain far to the north, 325 00:48:26,622 --> 00:48:28,101 and, once again, 326 00:48:28,182 --> 00:48:31,652 become part of this miraculous event in the Okavango, 327 00:48:31,742 --> 00:48:34,131 that is the Great Flood. 328 00:49:03,142 --> 00:49:05,019 In the making of ''The Great Flood'', 329 00:49:05,102 --> 00:49:07,411 the biggest challenge for the filming team 330 00:49:07,502 --> 00:49:09,333 was to capture the magical moment 331 00:49:09,422 --> 00:49:12,653 when new floodwater first transformed the desert. 332 00:49:16,542 --> 00:49:18,692 But to do this would mean crossing 333 00:49:18,782 --> 00:49:21,501 some of the most challenging terrain in the world, 334 00:49:22,502 --> 00:49:26,575 pitting themselves against the very water they'd come to film. 335 00:49:33,702 --> 00:49:36,216 We're right in the heart of the delta right now. 336 00:49:36,302 --> 00:49:37,974 The flood's been in here for a couple of weeks, 337 00:49:38,062 --> 00:49:40,178 but the real action's happening out west, 338 00:49:40,262 --> 00:49:43,937 across 20 kilometres of deep swampland. 339 00:49:44,302 --> 00:49:47,453 And our mission right now is to get this crane rig out there 340 00:49:47,542 --> 00:49:48,941 to where the action's really happening, 341 00:49:49,022 --> 00:49:52,298 and see if we can get a great new perspective on the flood coming in. 342 00:49:54,822 --> 00:49:56,892 ATTENBOROUGH: To achieve this new look, 343 00:49:56,982 --> 00:50:00,372 the team were using some of the latest camera technology. 344 00:50:00,462 --> 00:50:03,499 But first they had to find the advancing flood, 345 00:50:05,102 --> 00:50:08,981 and the only way to do this was from the air. 346 00:50:14,022 --> 00:50:16,661 Mike has worked here for more than 20 years, 347 00:50:16,742 --> 00:50:19,700 and knows that this will be a race against time. 348 00:50:22,982 --> 00:50:25,052 The flood was already well advanced, 349 00:50:25,142 --> 00:50:27,610 and wasn't going to wait for a film crew. 350 00:50:34,222 --> 00:50:36,497 Mike pinpointed the water's edge, 351 00:50:36,582 --> 00:50:40,621 and on his way back, laid a GPS trail to follow. 352 00:50:45,542 --> 00:50:47,533 The flight took only 20 minutes, 353 00:50:47,622 --> 00:50:51,171 but it would take the ground crew at least three days or more 354 00:50:51,262 --> 00:50:52,377 to get there. 355 00:50:54,782 --> 00:50:58,377 And there was no guarantee they'd get through the swamps. 356 00:51:01,502 --> 00:51:03,060 -Are you watching for crocodiles? -Yeah. 357 00:51:03,142 --> 00:51:04,336 Okay, good. 358 00:51:09,222 --> 00:51:11,782 ATTENBOROUGH: Fortunately, at this cooler time of year, 359 00:51:11,862 --> 00:51:15,821 crocodiles are less active and wouldn't pose a serious threat. 360 00:51:17,102 --> 00:51:20,253 The reason Richard's wading in crocodile-infested waters 361 00:51:20,342 --> 00:51:23,300 is that we're on this side, and we need to be on the other side, 362 00:51:23,382 --> 00:51:25,532 and he's wading so that we can see how deep it is 363 00:51:25,622 --> 00:51:27,180 for this vehicle to cross. 364 00:51:32,662 --> 00:51:34,857 ATTENBOROUGH: These trucks are specially adapted 365 00:51:34,942 --> 00:51:37,331 to cope with such extreme conditions. 366 00:51:39,302 --> 00:51:42,499 They can drive in water up to seven feet deep, 367 00:51:47,022 --> 00:51:50,332 and cross all but the boggiest terrain. 368 00:51:54,222 --> 00:51:58,295 Unfortunately, not all the equipment fared so well. 369 00:51:58,662 --> 00:52:01,699 I don't think this is gonna be much use to anyone. 370 00:52:04,222 --> 00:52:08,261 ATTENBOROUGH: But even the vehicles weren't immune to such punishing use. 371 00:52:09,502 --> 00:52:13,211 Problems always arise when you least expect it. 372 00:52:17,822 --> 00:52:20,973 This truck, which is our swamp truck, 373 00:52:21,062 --> 00:52:23,337 has decided 374 00:52:23,422 --> 00:52:26,220 to give us problems again. 375 00:52:26,302 --> 00:52:28,293 The dif has basically collapsed on us. 376 00:52:28,382 --> 00:52:31,055 We're running out of daylight at the moment, 377 00:52:31,862 --> 00:52:33,818 so we got to swap this out. 378 00:52:36,982 --> 00:52:40,054 ATTENBOROUGH: To film here, you have to be a jack of all trades, 379 00:52:40,142 --> 00:52:43,657 a filmmaker, a tracker and a mechanic. 380 00:52:46,302 --> 00:52:51,934 Despite some on-the-spot bush repairs, a replacement part had to be ordered in. 381 00:52:53,262 --> 00:52:54,377 Hello. 382 00:52:56,582 --> 00:52:57,697 (GROANS) 383 00:52:59,102 --> 00:53:01,218 It's going to be a long night in the bush. 384 00:53:03,222 --> 00:53:06,055 ATTENBOROUGH: All the crew could do now was wait. 385 00:53:13,182 --> 00:53:16,458 With the nearest garage over two days away by truck, 386 00:53:16,542 --> 00:53:19,420 there was only one way the new part could be delivered. 387 00:53:29,222 --> 00:53:33,738 Now the crew could get back on the road and start making up for lost time. 388 00:53:34,542 --> 00:53:36,658 -Are you all right? -MAN: Yeah, I'm good. 389 00:53:40,462 --> 00:53:43,852 ATTENBOROUGH: But they would have to choose their route carefully. 390 00:53:45,862 --> 00:53:48,092 The best way to pick a path is where the elephants cross, 391 00:53:48,182 --> 00:53:52,095 because they've got regular routes that are the shallowest places. 392 00:53:52,182 --> 00:53:54,332 But often where they've crossed, it's churned up the mud as well, 393 00:53:54,422 --> 00:53:56,538 so we try and stay slightly off to the edge of the path. 394 00:53:56,622 --> 00:53:58,180 But once you get into the middle of that, 395 00:53:58,262 --> 00:54:01,254 it's just hope like hell and keep going. 396 00:54:01,342 --> 00:54:04,459 Because it's probably deep and very soggy in the middle. 397 00:54:17,182 --> 00:54:20,891 Okay, this is getting a bit silly. We're officially stuck. 398 00:54:21,582 --> 00:54:24,460 ATTENBOROUGH: Mike's concerns proved well-founded. 399 00:54:24,542 --> 00:54:27,579 The shallower route was simply too boggy. 400 00:54:30,182 --> 00:54:35,051 That left the crew with no choice but to tackle the longer, deeper route, 401 00:54:35,142 --> 00:54:37,053 and hold their nerve. 402 00:54:50,102 --> 00:54:51,933 MAN: It's coming over your windows. 403 00:54:52,022 --> 00:54:54,536 (EXCLAIMS) I'm getting wet. 404 00:55:04,382 --> 00:55:07,101 (EXCLAIMS) Water's coming in! 405 00:55:15,502 --> 00:55:17,254 It's a little damp in here now. 406 00:55:43,142 --> 00:55:46,976 That was interesting, but we made it across the swamp! 407 00:55:47,062 --> 00:55:48,541 ATTENBOROUGH: Success! 408 00:55:48,622 --> 00:55:52,058 Mike and the team had finally got ahead of the flood. 409 00:55:56,662 --> 00:56:00,098 They were now in a truly privileged position, 410 00:56:00,182 --> 00:56:03,299 ready to capture the amazing transformation 411 00:56:03,382 --> 00:56:05,259 that was about to unfold. 412 00:56:09,062 --> 00:56:12,020 Okay, so drop the camera over the middle of the pool there. 413 00:56:15,062 --> 00:56:17,530 The flood had arrived. 414 00:56:18,702 --> 00:56:19,976 Here it comes. 415 00:56:35,422 --> 00:56:38,494 Three, two, one... 416 00:56:44,382 --> 00:56:48,898 ATTENBOROUGH: Using cranes and specially developed close-up camera systems, 417 00:56:48,982 --> 00:56:52,338 the Nature's Great Events team could finally set about 418 00:56:52,422 --> 00:56:54,936 bringing the advancing flood to life. 419 00:56:56,702 --> 00:56:58,613 This is one of those magical transformation moments, 420 00:56:58,702 --> 00:57:02,172 where you've got a landscape which is asleep that way, 421 00:57:02,262 --> 00:57:04,617 and you've got the flood, which is like the catalyst 422 00:57:04,702 --> 00:57:06,738 which is going to bring the landscape to life. 423 00:57:06,822 --> 00:57:10,371 And it's happening right in front of us, which is amazing. 424 00:57:10,462 --> 00:57:13,420 And we've got a bit of macro kit 425 00:57:13,502 --> 00:57:15,458 that exists nowhere else in the world, 426 00:57:15,542 --> 00:57:19,694 and we're able to just follow it at the really tiniest level. 427 00:57:30,622 --> 00:57:33,056 ATTENBOROUGH: This was the Great Flood, 428 00:57:33,142 --> 00:57:36,578 but filmed on a scale that had never been seen before. 429 00:57:52,822 --> 00:57:54,733 Seems like my hole is filling up. 430 00:57:55,382 --> 00:57:58,692 I'm going to get wet, Rick. I'm going to drown in three inches of water. 431 00:58:04,902 --> 00:58:09,453 ATTENBOROUGH: Each year, the magical flood rewards Mike with something new. 432 00:58:09,542 --> 00:58:14,252 Despite years of filming here, he'd never seen so many dragonflies. 433 00:58:19,862 --> 00:58:21,215 It's amazing, that, isn't it? 434 00:58:21,302 --> 00:58:23,293 Have you ever watched this happen before? 435 00:58:23,382 --> 00:58:24,735 It is amazing. 436 00:58:24,822 --> 00:58:27,939 I mean, you think this is going on all over the delta. 437 00:58:28,022 --> 00:58:30,741 Miles and miles and miles of water just spreading everywhere 438 00:58:30,822 --> 00:58:32,221 at this rate. 439 00:58:33,262 --> 00:58:34,456 Incredible. 440 00:58:35,182 --> 00:58:37,491 ATTENBOROUGH: And the team had managed to capture 441 00:58:37,582 --> 00:58:39,493 just a tiny part of it, 442 00:58:39,582 --> 00:58:45,054 revealing in intimate detail the character of the Great Flood.