1 00:00:02,469 --> 00:00:05,339 All rivers are on a quest, 2 00:00:07,241 --> 00:00:10,143 a constant mission to find the ocean. 3 00:00:13,146 --> 00:00:16,149 An endless cycle to move water 4 00:00:16,149 --> 00:00:18,518 across the vast blue planet. 5 00:00:23,357 --> 00:00:27,261 Along the way they support countless lives. 6 00:00:31,198 --> 00:00:35,035 But their odyssey is by no means easy. 7 00:00:38,538 --> 00:00:39,773 From ice 8 00:00:42,576 --> 00:00:44,044 to heat, 9 00:00:44,645 --> 00:00:46,246 obstacles abound. 10 00:00:48,382 --> 00:00:51,785 Yet, despite an ever-changing nature, 11 00:00:51,785 --> 00:00:55,222 A river always finds its way - 12 00:00:55,222 --> 00:00:56,657 on the journey 13 00:00:56,657 --> 00:00:59,126 from Source to Sea. 14 00:01:30,524 --> 00:01:34,761 Morning dawns across an alpine world. 15 00:01:41,234 --> 00:01:43,770 This is the roof of southern Africa. 16 00:01:49,176 --> 00:01:51,712 Up here, shrouded in the mist, 17 00:01:51,712 --> 00:01:54,414 something very special is happening. 18 00:01:58,185 --> 00:02:01,188 Clouds laden with moisture 19 00:02:01,188 --> 00:02:03,090 arrive from afar 20 00:02:03,090 --> 00:02:06,727 to empty their precious loads among the crags. 21 00:02:12,099 --> 00:02:16,203 It's the first step in the perpetual cycling of water 22 00:02:16,203 --> 00:02:18,105 that nourishes the planet. 23 00:02:23,543 --> 00:02:27,247 Moisture evaporating off the Earth's surface 24 00:02:27,247 --> 00:02:30,384 travels as gas in the clouds, 25 00:02:32,753 --> 00:02:34,488 where it rises up, 26 00:02:34,488 --> 00:02:37,824 before eventually falling back to Earth, 27 00:02:37,824 --> 00:02:39,793 often in the mountains. 28 00:02:46,133 --> 00:02:50,337 Indeed, mountains are where rivers are born. 29 00:02:52,372 --> 00:02:54,574 And at the top of the world, 30 00:02:54,574 --> 00:02:57,310 there is only one way to go - 31 00:02:58,345 --> 00:02:59,546 down. 32 00:03:03,183 --> 00:03:06,653 Flowing east down the mountainside, 33 00:03:06,653 --> 00:03:11,491 the young river has unwittingly set course for the Indian ocean. 34 00:03:13,427 --> 00:03:15,762 On the other side of the escarpment 35 00:03:15,762 --> 00:03:18,565 other streams flow west, 36 00:03:18,565 --> 00:03:21,635 choosing a vastly different path 37 00:03:21,635 --> 00:03:25,572 that will take them across southern Africa's arid interior. 38 00:03:27,707 --> 00:03:32,145 But this river has a more immediate challenge to face. 39 00:03:34,281 --> 00:03:38,652 At these heights it's icy cold almost all the time 40 00:03:39,486 --> 00:03:42,456 and no sooner has the water started moving, 41 00:03:42,456 --> 00:03:44,524 then it's frozen solid. 42 00:03:48,595 --> 00:03:52,199 Trapped in the ice wall of the waterfall, 43 00:03:52,199 --> 00:03:56,103 the new river's journey draws to an abrupt halt 44 00:03:56,103 --> 00:03:58,105 just yards from its source. 45 00:04:04,444 --> 00:04:08,582 Yet, this morning there is the promise of something 46 00:04:08,582 --> 00:04:12,052 that can unlock it from its icy shackles. 47 00:04:21,561 --> 00:04:24,197 It's the beginning of spring. 48 00:04:26,299 --> 00:04:30,403 For the first time in months, temperatures are rising 49 00:04:30,403 --> 00:04:34,307 and the sun shines warm across the alpine world. 50 00:05:05,071 --> 00:05:09,543 Drop by drop the water escapes from its frozen prison. 51 00:05:33,300 --> 00:05:37,437 Gravity, the driving force of all rivers on earth, 52 00:05:38,238 --> 00:05:41,575 pulls the water down the side of the mountain. 53 00:05:43,143 --> 00:05:46,479 Gathering momentum, it babbles along, 54 00:05:46,479 --> 00:05:50,617 picking out the rocky path of least resistance. 55 00:05:59,292 --> 00:06:01,528 Under the heat of the sun, 56 00:06:01,528 --> 00:06:04,030 river is born. 57 00:06:05,198 --> 00:06:07,534 Small and icy, 58 00:06:07,534 --> 00:06:09,803 the young river now descends 59 00:06:09,803 --> 00:06:12,138 though the mountains of its birth. 60 00:06:12,739 --> 00:06:16,276 It's still thousands of feet above sea level 61 00:06:16,276 --> 00:06:21,281 and even the rays of springtime sun cannot thaw it completely. 62 00:06:26,152 --> 00:06:30,690 Only a hardy few can handle these frigid conditions. 63 00:06:32,792 --> 00:06:35,195 The first sign of animal life 64 00:06:35,195 --> 00:06:37,831 is a creature not typically known 65 00:06:37,831 --> 00:06:41,268 for its cold water endurance; 66 00:06:41,268 --> 00:06:42,769 a tadpole. 67 00:06:45,538 --> 00:06:48,575 These Maluti river frog tadpoles 68 00:06:48,575 --> 00:06:51,344 seem quite at home under the ice. 69 00:06:52,545 --> 00:06:56,516 The little amphibians appear to have a secret weapon 70 00:06:56,516 --> 00:06:59,953 to help them survive in the frigid waters. 71 00:07:01,454 --> 00:07:02,956 Antifreeze. 72 00:07:05,425 --> 00:07:09,329 When ice crystals start forming on their skin 73 00:07:09,329 --> 00:07:11,765 it triggers the production of glucose, 74 00:07:11,765 --> 00:07:15,735 which prevents the dehydration and shrinking of cells - 75 00:07:17,304 --> 00:07:20,273 keeping the little amphibians from freezing solid. 76 00:07:23,576 --> 00:07:27,047 The ability to produce their own versions of antifreeze 77 00:07:27,047 --> 00:07:30,817 is a talent shared by several amphibians 78 00:07:30,817 --> 00:07:32,686 living in icy realms. 79 00:07:38,558 --> 00:07:41,528 The tadpole's parents are close at hand. 80 00:07:44,464 --> 00:07:48,635 Maluti river frogs are also known as ice frogs. 81 00:07:54,641 --> 00:07:58,345 They inhabit limited ranges across the mountains. 82 00:08:05,218 --> 00:08:10,557 Living in the rivers up here is their unusual choice of food - 83 00:08:15,295 --> 00:08:17,664 Freshwater crabs. 84 00:08:26,206 --> 00:08:31,378 The crustaceans are equally at home above or below the ice 85 00:08:31,378 --> 00:08:35,215 and form a large part of the ice frog's diet. 86 00:08:38,284 --> 00:08:42,155 Freshwater crabs aren't known as great travelers, 87 00:08:42,155 --> 00:08:44,791 and this one will spend its whole life 88 00:08:44,791 --> 00:08:47,427 along this stretch of riverbank - 89 00:08:52,365 --> 00:08:56,669 Where he must sometimes sneak past sleeping frogs. 90 00:09:15,422 --> 00:09:17,223 Further downstream 91 00:09:17,223 --> 00:09:20,460 other waterside residents are also coming out 92 00:09:20,460 --> 00:09:23,663 to enjoy the first signs of spring. 93 00:09:43,049 --> 00:09:46,052 The ice rat has no antifreeze, 94 00:09:46,052 --> 00:09:52,058 but it's got a few other tricks up its sleeve to help stay warm. 95 00:09:52,058 --> 00:09:55,662 The social rodents make their homes beneath the earth 96 00:09:55,662 --> 00:09:57,297 in burrows 97 00:09:57,297 --> 00:10:00,633 of multiple interlinked chambers and entrances. 98 00:10:01,768 --> 00:10:04,504 In these underground hideouts 99 00:10:04,504 --> 00:10:08,708 the rats keep cozy even when it's freezing outside. 100 00:10:13,346 --> 00:10:17,283 When the ice rats do venture outdoors to forage, 101 00:10:17,283 --> 00:10:20,286 they have a few ways to maintain their body temperatures. 102 00:10:23,356 --> 00:10:26,526 Thick fur helps a great deal, 103 00:10:26,526 --> 00:10:30,563 while small ears and tails limit heat loss. 104 00:10:34,601 --> 00:10:39,372 But according to scientists, their favorite way to stay snug 105 00:10:39,372 --> 00:10:40,807 is sunbathing. 106 00:10:46,546 --> 00:10:49,249 With a little bit of cuddling thrown in. 107 00:10:51,885 --> 00:10:54,420 But for that you need to find someone 108 00:10:54,420 --> 00:10:56,523 who also fancies a snuggle. 109 00:11:02,762 --> 00:11:06,199 The ice rats are joined on the banks of the river 110 00:11:06,199 --> 00:11:09,536 by a pair of Drakensberg rock jumpers. 111 00:11:13,806 --> 00:11:17,610 They've been waiting all morning for the ground to thaw, 112 00:11:17,610 --> 00:11:20,513 so they can scratch around for some breakfast. 113 00:11:25,685 --> 00:11:29,389 Other avian locals soon join to feed. 114 00:11:35,328 --> 00:11:40,500 Up here it's not just the early birds that get the worms. 115 00:11:52,845 --> 00:11:56,049 Overhead a vulture soars. 116 00:12:04,190 --> 00:12:05,692 From a height, 117 00:12:05,692 --> 00:12:09,662 the twisting river glimmers like a serpent in the sun. 118 00:12:13,366 --> 00:12:15,435 Continuing its descent, 119 00:12:15,435 --> 00:12:19,339 it leaves the high peaks and enters freefall, 120 00:12:20,306 --> 00:12:22,709 becoming an unstoppable force. 121 00:12:25,745 --> 00:12:28,581 The water surges down the mountainside, 122 00:12:28,581 --> 00:12:31,517 moving faster than it ever will again. 123 00:12:42,261 --> 00:12:45,398 Waterfalls cascade into deep pools 124 00:12:45,398 --> 00:12:47,767 hollowed out by eons of crashing flow. 125 00:13:02,215 --> 00:13:05,051 The young river is well on its way now, 126 00:13:05,051 --> 00:13:09,422 having left its icy origins for bubbling rapids. 127 00:13:19,198 --> 00:13:23,369 The serenity of the cascades hides their true power. 128 00:13:27,573 --> 00:13:32,578 Water has the ability to slice through solid rock. 129 00:13:38,284 --> 00:13:40,620 Over many millions of years, 130 00:13:40,620 --> 00:13:43,489 the river has carved out a path 131 00:13:43,489 --> 00:13:46,526 through one of the hardest stones - 132 00:13:46,526 --> 00:13:47,660 granite. 133 00:13:49,195 --> 00:13:53,666 Massive boulders have scoured out cavernous holes. 134 00:13:56,235 --> 00:14:00,073 But how does water cut though stone? 135 00:14:01,307 --> 00:14:04,744 The answer lies both in the water's corrosive 136 00:14:04,744 --> 00:14:06,646 and abrasive qualities. 137 00:14:07,680 --> 00:14:10,750 The naturally acidic river water 138 00:14:10,750 --> 00:14:13,152 dissolves the minerals like quartz 139 00:14:13,152 --> 00:14:15,421 that bind the rock together. 140 00:14:17,390 --> 00:14:21,594 Then small particles of sediment carried by the river 141 00:14:21,594 --> 00:14:24,764 continuously pummel the compromised rock, 142 00:14:24,764 --> 00:14:26,566 wearing it down. 143 00:14:28,668 --> 00:14:31,304 These microscopic stones 144 00:14:31,304 --> 00:14:34,807 chip away at the underlying rock as they move, 145 00:14:34,807 --> 00:14:37,777 eventually cutting deep grooves. 146 00:14:39,412 --> 00:14:43,483 In this way rivers excavate valleys, 147 00:14:43,483 --> 00:14:46,652 changing the very landscape through which they flow. 148 00:14:58,331 --> 00:15:00,566 The young river pushes east, 149 00:15:00,566 --> 00:15:03,436 forging its way through the rocky terrain 150 00:15:03,436 --> 00:15:05,638 at the base of the mountains, 151 00:15:05,638 --> 00:15:08,241 towards its ultimate goal - 152 00:15:08,241 --> 00:15:09,275 the sea. 153 00:15:14,480 --> 00:15:18,985 But the journey from source to sea is not an easy one. 154 00:15:21,554 --> 00:15:26,058 The river is about to face its biggest challenge yet. 155 00:15:27,093 --> 00:15:32,465 Now as it enters the flatter lands at the base of the peaks 156 00:15:32,465 --> 00:15:35,034 it slows to a crawl. 157 00:15:40,072 --> 00:15:41,474 It's hotter too. 158 00:15:44,544 --> 00:15:47,046 It's the peak of the dry season. 159 00:15:48,848 --> 00:15:52,051 Rain is like a distant memory. 160 00:15:53,653 --> 00:15:58,691 This thirsty land has sucked the river almost dry. 161 00:16:01,027 --> 00:16:04,463 Here the wilderness is home to many animals, 162 00:16:05,264 --> 00:16:08,701 all of which rely on the river for survival. 163 00:16:24,317 --> 00:16:29,188 Few are better known for their giant thirsts than elephants. 164 00:16:34,594 --> 00:16:38,264 Elephants are considered a water dependent species 165 00:16:38,264 --> 00:16:41,334 and need to drink every day, 166 00:16:41,334 --> 00:16:43,169 especially when it's hot. 167 00:16:44,437 --> 00:16:49,408 An adult can consume upwards of 50 gallons a day, 168 00:16:51,444 --> 00:16:54,180 making the demands of a thirsty herd 169 00:16:54,180 --> 00:16:56,415 on the meagre river significant. 170 00:17:24,443 --> 00:17:28,180 It's not only the elephants that need the river's moisture. 171 00:17:31,150 --> 00:17:33,552 Camelthorn trees on its banks 172 00:17:33,552 --> 00:17:37,690 use long roots to draw water from the sandy soil. 173 00:17:39,792 --> 00:17:44,030 These trees in turn elicit their own visitors. 174 00:17:46,632 --> 00:17:49,435 Like this troop of Vervet monkeys, 175 00:17:49,435 --> 00:17:53,005 one of southern Africa's most abundant primates. 176 00:17:56,142 --> 00:17:59,779 They're here for the nutrient rich seedpods. 177 00:18:07,353 --> 00:18:09,422 Although the trees are epitomized 178 00:18:09,422 --> 00:18:11,524 by their sharp thorns, 179 00:18:11,524 --> 00:18:15,027 the monkeys seem totally unconcerned, 180 00:18:15,027 --> 00:18:18,030 feeding happily among the spiny barbs. 181 00:18:20,299 --> 00:18:21,801 The trees' seedpods 182 00:18:21,801 --> 00:18:26,205 provide a valuable source of protein and other nutrients 183 00:18:26,205 --> 00:18:28,174 for the omnivorous Vervets, 184 00:18:28,174 --> 00:18:31,043 which have a wide and varied diet. 185 00:18:32,611 --> 00:18:38,217 Like the elephants, the monkeys also need to drink daily, 186 00:18:38,217 --> 00:18:40,453 making this riverside real estate 187 00:18:40,453 --> 00:18:43,222 excellent primate property. 188 00:18:44,590 --> 00:18:47,360 One upside to the dry season 189 00:18:47,360 --> 00:18:50,296 is that the exposed sandy beaches 190 00:18:50,296 --> 00:18:53,599 provide easy access to the water. 191 00:18:55,768 --> 00:19:00,006 For this Southern white rhino mother and calf, 192 00:19:00,006 --> 00:19:01,407 a visit to the river 193 00:19:01,407 --> 00:19:05,144 is also an important part of their daily routine. 194 00:19:10,516 --> 00:19:15,588 While the calf is only a few weeks old and still nursing, 195 00:19:15,588 --> 00:19:17,690 mum needs to drink 196 00:19:17,690 --> 00:19:21,727 in order to produce gallons of rich milk. 197 00:19:37,777 --> 00:19:42,515 Each new generation of white rhinos is invaluable, 198 00:19:42,515 --> 00:19:47,119 for it helps secure a future for the highly endangered species. 199 00:19:57,129 --> 00:20:01,267 After facing near extinction in the nineteen sixties, 200 00:20:01,267 --> 00:20:04,570 population numbers are still very low 201 00:20:07,306 --> 00:20:10,810 and every healthy rhino baby like this one 202 00:20:10,810 --> 00:20:13,345 is a small conservation victory. 203 00:20:24,190 --> 00:20:27,760 The little calf is still very reliant on her mother 204 00:20:27,760 --> 00:20:30,229 for protection and support. 205 00:20:39,572 --> 00:20:44,643 Mum is in turn an attentive and capable parent. 206 00:20:44,643 --> 00:20:48,347 Few predators would dare challenge her - 207 00:20:48,347 --> 00:20:53,519 3,700 pounds of muscle and thick hide behind a smooth-tipped horn 208 00:20:53,519 --> 00:20:56,655 are intimidating to even the biggest lions. 209 00:20:59,525 --> 00:21:02,628 But there are some things in a young rhino's life 210 00:21:02,628 --> 00:21:05,431 even her mother can't help with. 211 00:21:10,703 --> 00:21:12,338 Like ticks. 212 00:21:14,273 --> 00:21:16,008 She's covered in them. 213 00:21:18,277 --> 00:21:23,182 Luckily for the calf, in nature if there's a job to be done, 214 00:21:23,182 --> 00:21:25,584 there's generally someone to do it. 215 00:21:30,789 --> 00:21:35,528 Oxpeckers have identified tick cleaning as a niche market. 216 00:21:40,566 --> 00:21:43,802 The little bird gets to work on the infestation. 217 00:21:47,706 --> 00:21:52,211 It's a win-win situation for bird and beast. 218 00:22:18,404 --> 00:22:19,772 Treatment complete, 219 00:22:19,772 --> 00:22:23,509 the industrious birds move on to mum. 220 00:22:44,697 --> 00:22:49,268 Further downstream, a group of vultures has come to the water 221 00:22:49,268 --> 00:22:51,704 for a seemingly unlikely reason. 222 00:22:57,676 --> 00:23:00,279 While the birds have a reputation 223 00:23:00,279 --> 00:23:01,747 for being dirty scavengers, 224 00:23:02,581 --> 00:23:06,385 these White-backed vultures are here for a bath. 225 00:23:10,456 --> 00:23:12,157 Like all birds, 226 00:23:12,157 --> 00:23:16,328 they need to keep their feathers free of excess oil and dirt 227 00:23:17,196 --> 00:23:19,365 so they line up for a wash. 228 00:23:30,276 --> 00:23:35,748 Next they assume open winged poses to dry off in the sun. 229 00:23:41,620 --> 00:23:46,392 It's a routine cleaning that ensures they're in tip top shape 230 00:23:46,392 --> 00:23:49,595 when it comes time to take to the skies. 231 00:23:59,638 --> 00:24:04,209 From above the vultures look for carcasses to feed on, 232 00:24:04,209 --> 00:24:06,245 for they don't hunt themselves. 233 00:24:09,415 --> 00:24:12,518 But they're out of luck this morning. 234 00:24:12,518 --> 00:24:14,486 The only predators around 235 00:24:14,486 --> 00:24:17,556 are more interested in a nap than a kill. 236 00:24:21,193 --> 00:24:23,195 African wild dogs may be 237 00:24:23,195 --> 00:24:26,532 some of the most successful predators on the continent, 238 00:24:26,532 --> 00:24:29,568 but right now it's too hot for them to hunt. 239 00:24:32,237 --> 00:24:36,175 Like wolves they're extremely social animals, 240 00:24:36,175 --> 00:24:40,713 living in groups governed by an alpha male and female. 241 00:24:43,582 --> 00:24:47,786 The dogs once ranged widely across sub-Saharan Africa, 242 00:24:48,821 --> 00:24:51,490 from mountainous areas to desert. 243 00:24:57,296 --> 00:25:00,466 Nowadays they are considered endangered, 244 00:25:00,466 --> 00:25:04,770 with only an estimated 39 sub-populations left 245 00:25:04,770 --> 00:25:06,705 within Africa. 246 00:25:13,612 --> 00:25:16,582 Around a bend of the desiccated river, 247 00:25:16,582 --> 00:25:19,718 another threatened species makes its way. 248 00:25:22,688 --> 00:25:24,456 The African elephant 249 00:25:24,456 --> 00:25:27,626 is also facing critical population losses. 250 00:25:29,361 --> 00:25:31,196 Like the wild dogs, 251 00:25:31,196 --> 00:25:36,034 elephants need vast amounts of space to roam and feed in. 252 00:25:37,636 --> 00:25:41,507 Theirs is a restless and nomadic life, 253 00:25:41,507 --> 00:25:46,478 always on the move in search of food, water and mates. 254 00:25:50,115 --> 00:25:53,685 And the river is an important part of their journey. 255 00:25:55,854 --> 00:25:59,258 They use its winding path like a road, 256 00:25:59,258 --> 00:26:01,794 mapping out the easiest migration routes 257 00:26:01,794 --> 00:26:03,962 between feeding grounds. 258 00:26:05,397 --> 00:26:07,366 Staying close to the river 259 00:26:07,366 --> 00:26:10,068 ensures they have access to water, 260 00:26:10,068 --> 00:26:13,338 which they need for more than just drinking. 261 00:26:26,585 --> 00:26:28,787 The huge mammals keep cool 262 00:26:28,787 --> 00:26:32,291 by taking regular mud baths along the way. 263 00:26:37,329 --> 00:26:41,200 Mud bathing is common practice for elephants, 264 00:26:41,200 --> 00:26:45,304 keeping their surprisingly sensitive skin protected 265 00:26:45,304 --> 00:26:48,474 from both the sun and parasites. 266 00:27:09,628 --> 00:27:10,762 Down the way, 267 00:27:10,762 --> 00:27:14,800 where the waning river is little more than a dirt pit, 268 00:27:14,800 --> 00:27:18,704 there's another mighty herbivore with an affinity for mud. 269 00:27:21,340 --> 00:27:25,177 This buffalo bull is a senior citizen. 270 00:27:25,177 --> 00:27:28,213 Retired from a position at the head of the herd 271 00:27:29,181 --> 00:27:33,418 now relegated to a life of solitude on the riverbanks. 272 00:27:50,569 --> 00:27:52,638 But he's not alone today. 273 00:28:04,049 --> 00:28:05,651 He's being watched 274 00:28:05,651 --> 00:28:09,187 by a pair of Africa's most powerful predators. 275 00:28:11,690 --> 00:28:14,126 A young male lion 276 00:28:15,360 --> 00:28:17,195 and his brother. 277 00:28:19,031 --> 00:28:22,067 They might not have full manes yet 278 00:28:22,067 --> 00:28:27,239 but they've got the power to pull down the 1,900 pound bull. 279 00:28:35,781 --> 00:28:38,450 The ambush hunters hunker down. 280 00:28:40,419 --> 00:28:44,690 They need him to get close enough for them to pounce. 281 00:28:49,227 --> 00:28:50,762 He can't see them. 282 00:28:54,099 --> 00:28:56,368 But he can smell a trap. 283 00:29:17,122 --> 00:29:20,993 This old bull has lived through many a lion hunt. 284 00:29:23,495 --> 00:29:27,199 Experience tells him to beat a hasty retreat. 285 00:29:44,082 --> 00:29:47,986 The savanna kings will have to look elsewhere for their dinner. 286 00:29:57,462 --> 00:29:59,798 In the greying evening sky, 287 00:29:59,798 --> 00:30:04,569 a rumble of thunder signals an end to the dry season. 288 00:30:23,355 --> 00:30:27,492 After months of thirst, the rain soaks the land, 289 00:30:27,492 --> 00:30:30,495 bringing respite and rejuvenation. 290 00:31:00,492 --> 00:31:06,264 Dawn beaks to reveal a fresh and renewed world. 291 00:31:14,339 --> 00:31:18,510 Further downstream, the effects of the rain are visible 292 00:31:18,510 --> 00:31:21,613 as swollen tributaries feed the river, 293 00:31:21,613 --> 00:31:26,051 which grows deeper and wider than ever before. 294 00:31:33,258 --> 00:31:35,794 Flowing along in this fashion, 295 00:31:35,794 --> 00:31:40,599 it leaves the wide open plains and rocky hills of the bushveld 296 00:31:40,599 --> 00:31:44,169 and enters the tropical coastal zone. 297 00:31:47,272 --> 00:31:50,108 Closer to the Indian ocean, 298 00:31:50,108 --> 00:31:54,312 both the river and the surroundings change once more. 299 00:32:07,392 --> 00:32:11,530 The river relaxes into a languid stillness, 300 00:32:11,530 --> 00:32:16,768 widening across its flood plain and depositing rich sediment 301 00:32:16,768 --> 00:32:21,273 that fuels abundant growth around, and within. 302 00:32:50,669 --> 00:32:55,240 Water birds make a good living fishing in the rich waters. 303 00:32:56,441 --> 00:33:02,447 The regal heron uses a long beak to spear unsuspecting fish. 304 00:33:11,289 --> 00:33:15,160 While the king fisher dive bombs his quarry. 305 00:33:30,208 --> 00:33:32,177 There's another bird here 306 00:33:32,177 --> 00:33:36,281 that prefers the wetland's side salads to fishy mains. 307 00:33:43,855 --> 00:33:48,627 The Palm nut vulture is not what you'd expect a bird of prey. 308 00:33:52,330 --> 00:33:56,534 While the smell of rotting meat would excite its cousins, 309 00:33:56,534 --> 00:33:59,704 this vulture prefers the vegetarian menu. 310 00:34:02,774 --> 00:34:06,678 It lives mostly off the fruits of the Palm nut tree. 311 00:34:14,119 --> 00:34:15,320 There are others around 312 00:34:15,320 --> 00:34:19,124 who also favor the easy pickings of the Palm nuts' bounty. 313 00:34:21,660 --> 00:34:26,665 Samango monkeys share the big birds' enthusiasm for palm nuts. 314 00:34:28,700 --> 00:34:33,672 Also called Blue monkeys, they are rare in southern Africa, 315 00:34:33,672 --> 00:34:37,075 only living in coastal forests like this one. 316 00:34:40,312 --> 00:34:44,416 These Samangos have made excellent waterside homes here, 317 00:34:46,318 --> 00:34:48,386 with quirky neighbors 318 00:34:50,422 --> 00:34:52,657 and plenty of food. 319 00:35:05,704 --> 00:35:09,708 On the calm surface of the river, beauty blossoms. 320 00:35:15,246 --> 00:35:19,017 Water lilies are well suited to a life aquatic. 321 00:35:24,155 --> 00:35:28,193 Their wide, round leaves float on the surface 322 00:35:28,193 --> 00:35:32,731 while long hollow stems reach down to the river floor. 323 00:35:35,767 --> 00:35:39,304 It's the lilies' flowers that are the most alluring. 324 00:35:42,374 --> 00:35:45,176 Their perfume and bright colors 325 00:35:45,176 --> 00:35:48,313 are simply irresistible to many insects. 326 00:35:51,282 --> 00:35:56,021 But the lilies serve other river locals besides the bees. 327 00:36:01,459 --> 00:36:04,462 They provide the perfect hunting platform 328 00:36:04,462 --> 00:36:07,432 for one very unusual creature. 329 00:36:10,535 --> 00:36:14,439 These long legs and spindly claws 330 00:36:14,439 --> 00:36:16,608 belong to the African jacana. 331 00:36:30,688 --> 00:36:36,561 This striking bird has evolved long, thin feet, which enable it 332 00:36:36,561 --> 00:36:40,432 to distribute its weight evenly over the lily pads, 333 00:36:40,432 --> 00:36:41,766 so it doesn't sink 334 00:36:41,766 --> 00:36:44,702 while searching for insects among the leaves. 335 00:36:49,407 --> 00:36:52,243 These three are a family unit, 336 00:36:52,243 --> 00:36:55,580 but not the kind you'd necessarily expect. 337 00:36:59,250 --> 00:37:01,419 This bird is a single dad. 338 00:37:03,288 --> 00:37:08,026 Jacanas are unlike most birds insofar as 339 00:37:08,026 --> 00:37:11,396 it is the male who cares exclusively for the chicks. 340 00:37:16,101 --> 00:37:20,271 The chicks' mother may have mated with multiple males, 341 00:37:20,271 --> 00:37:24,442 leaving each one with a clutch of eggs to raise on their own. 342 00:37:28,346 --> 00:37:31,549 This unorthodox system of breeding 343 00:37:31,549 --> 00:37:35,487 evolved to compensate for an extraordinarily high rate 344 00:37:35,487 --> 00:37:37,622 of egg loss to predators. 345 00:37:42,093 --> 00:37:45,363 The world of the jacana has, in effect, 346 00:37:45,363 --> 00:37:49,000 turned the female into an "egg-making machine," 347 00:37:50,168 --> 00:37:53,771 leaving the fathers to incubate and care for the eggs. 348 00:37:59,477 --> 00:38:02,614 This dad has done his duty well. 349 00:38:06,217 --> 00:38:11,389 He's got not one but two healthy fledglings that are learning 350 00:38:11,389 --> 00:38:15,093 how to navigate a life of walking on water. 351 00:38:16,127 --> 00:38:20,098 The main thing they need to figure out is how to catch food, 352 00:38:22,734 --> 00:38:24,536 without sinking. 353 00:38:35,180 --> 00:38:37,282 So far so good. 354 00:39:09,647 --> 00:39:13,051 As the river moves closer to the Indian ocean, 355 00:39:13,051 --> 00:39:15,720 strange shapes appear within. 356 00:39:20,758 --> 00:39:25,330 Indeed, it's not only wildlife that uses these waterways. 357 00:39:32,370 --> 00:39:36,140 Fish traps provide for subsistence fishermen 358 00:39:36,140 --> 00:39:39,410 who have long lived off the coastal estuaries. 359 00:39:41,579 --> 00:39:46,317 This ancient method has been passed down through generations. 360 00:39:47,352 --> 00:39:51,623 It's carefully designed to guide the fish through a passage 361 00:39:51,623 --> 00:39:54,158 and into the heart-shaped trap. 362 00:39:56,261 --> 00:40:00,265 The structures are built so that only big fish get trapped, 363 00:40:00,265 --> 00:40:03,601 while small fish can move in and out. 364 00:40:30,628 --> 00:40:33,731 This form of fishing remains sustainable, 365 00:40:33,731 --> 00:40:34,732 striking a balance 366 00:40:34,732 --> 00:40:37,635 between the needs of the people that live here 367 00:40:37,635 --> 00:40:40,471 and the conservation of those species 368 00:40:40,471 --> 00:40:43,041 that use these waters to breed. 369 00:41:13,738 --> 00:41:17,542 During the summer months, the river is full of fish 370 00:41:17,542 --> 00:41:21,713 with species like bream, grunter and mullet 371 00:41:21,713 --> 00:41:24,282 finding their way into the traps. 372 00:41:27,518 --> 00:41:33,057 But now, at the start of spring, large fish have yet to arrive. 373 00:41:40,865 --> 00:41:46,404 Like all fishing endeavors there is no guarantee of success. 374 00:41:55,146 --> 00:41:59,317 Sometimes fishermen must contend with more than bad luck. 375 00:42:07,125 --> 00:42:10,728 Other riverside locals sabotage their traps. 376 00:42:14,632 --> 00:42:18,636 The calm, shallow water is perfect for hippos. 377 00:42:21,439 --> 00:42:25,610 These amphibious mammals are incredibly strong, 378 00:42:25,610 --> 00:42:30,248 and have been known to trash the fish traps on a whim. 379 00:42:35,119 --> 00:42:37,488 Below the surface, the fish benefit. 380 00:42:40,391 --> 00:42:43,194 This trap can hold them no more. 381 00:43:20,331 --> 00:43:23,568 At last, the ocean is within reach. 382 00:43:25,837 --> 00:43:31,175 Yet here the river goes through one of its most extreme changes. 383 00:43:32,477 --> 00:43:34,645 This close to the ocean 384 00:43:34,645 --> 00:43:37,582 the very make-up of the water is changing. 385 00:43:40,251 --> 00:43:42,286 Mixing with the salty sea 386 00:43:42,286 --> 00:43:46,057 it has become, for the first time, saline. 387 00:43:49,627 --> 00:43:51,462 While the brackish water 388 00:43:51,462 --> 00:43:54,465 would be too extreme for most plants to survive in, 389 00:43:54,465 --> 00:43:58,803 one very unusual tree still thrives here. 390 00:44:00,705 --> 00:44:04,242 Mangrove trees are uniquely designed 391 00:44:04,242 --> 00:44:06,310 to survive in salty water 392 00:44:06,310 --> 00:44:10,214 with roots that penetrate the mud at low tide, 393 00:44:10,214 --> 00:44:12,383 acting as snorkels during high tide. 394 00:44:14,085 --> 00:44:17,355 They also employ a complex filtration system 395 00:44:18,222 --> 00:44:20,458 to keep out most of the salt. 396 00:44:24,161 --> 00:44:27,565 Their success in this difficult habitat 397 00:44:27,565 --> 00:44:33,170 in turn supports others that call this coastal zone home. 398 00:44:54,358 --> 00:44:58,162 Crabs feed on fallen debris from the trees, 399 00:44:58,162 --> 00:45:01,432 scurrying to the safety of their holes when threatened. 400 00:45:04,368 --> 00:45:06,037 Their constant gardening 401 00:45:06,037 --> 00:45:09,040 recycles nutrients back into the earth, 402 00:45:09,040 --> 00:45:11,709 fueling the growth of more mangroves. 403 00:45:16,581 --> 00:45:17,815 At high tide 404 00:45:17,815 --> 00:45:23,421 the trees also provide a shelter for numerous juvenile fish. 405 00:45:25,089 --> 00:45:28,125 These crowd around fallen branches, 406 00:45:28,125 --> 00:45:30,328 keeping out of sight and out of danger. 407 00:45:34,398 --> 00:45:37,635 One day they will be big enough to follow the river 408 00:45:37,635 --> 00:45:40,271 on the final leg of its journey 409 00:45:40,271 --> 00:45:42,039 out into the ocean. 410 00:45:48,179 --> 00:45:52,617 Once past the mangroves, the river finally meets the sea. 411 00:45:56,721 --> 00:46:00,725 At the mouth it spills into the warm Indian ocean, 412 00:46:02,660 --> 00:46:04,695 bringing with it nutrients 413 00:46:04,695 --> 00:46:08,999 to feed those living on the inshore reef systems. 414 00:46:10,067 --> 00:46:15,373 Here, finally the river ceases to be separate from the ocean. 415 00:46:20,211 --> 00:46:21,746 Beyond the waves, 416 00:46:21,746 --> 00:46:25,516 life flourishes along vivid coral havens. 417 00:46:28,052 --> 00:46:31,822 It's an excellent example of a healthy estuary 418 00:46:31,822 --> 00:46:33,758 feeding into a vibrant ocean, 419 00:46:33,758 --> 00:46:38,529 where marine life can live and breed in abundance. 420 00:46:46,170 --> 00:46:47,705 This river's journey 421 00:46:47,705 --> 00:46:52,610 has taken it past a myriad of landscapes and characters. 422 00:46:52,610 --> 00:46:57,481 The water it carried has floated high over the mountains, 423 00:46:58,449 --> 00:47:00,651 quenched giant thirsts, 424 00:47:01,585 --> 00:47:03,487 and cut through rock. 425 00:47:06,190 --> 00:47:10,628 Now it has come to rest in the mighty Indian ocean. 426 00:47:12,029 --> 00:47:14,598 But its quest will not stop there. 427 00:47:15,599 --> 00:47:18,669 One day, in a place far away, 428 00:47:18,669 --> 00:47:23,474 the same water will embark on another epic journey - 429 00:47:24,075 --> 00:47:28,679 from Source to Sea. 430 00:47:30,147 --> 00:47:38,155 ♪♪ 431 00:47:38,155 --> 00:47:46,163 ♪♪ 432 00:47:46,163 --> 00:47:54,171 ♪♪