1 00:00:44,543 --> 00:00:47,239 Africa is dominated by deserts... 2 00:00:47,713 --> 00:00:51,911 ...from the Kalahari in the south to the mighty Sahara in the north. 3 00:00:55,921 --> 00:00:57,684 These are fascinating worlds... 4 00:00:57,990 --> 00:01:01,118 each one unique... all a challenge... 5 00:01:04,563 --> 00:01:08,624 Yet life can conquer them... and in the most surprising ways. 6 00:01:20,979 --> 00:01:25,211 This is an epic journey across Africa's magnificent deserts, 7 00:01:25,951 --> 00:01:29,114 a story of survival against the odds. 8 00:01:48,407 --> 00:01:49,465 Africa. 9 00:01:50,776 --> 00:01:54,234 Seen from space, great swathes of sand and rock 10 00:01:54,346 --> 00:01:56,371 cover more than half the continent. 11 00:01:59,818 --> 00:02:02,184 In the far south, bordering the Atlantic, 12 00:02:02,321 --> 00:02:05,848 is the world's most ancient desert the Namib. 13 00:02:09,828 --> 00:02:14,424 For 80 million years, cold dry winds have swept in from the ocean, 14 00:02:14,566 --> 00:02:19,868 denying the land moisture and piling enormous sand dunes against the shore... 15 00:02:33,118 --> 00:02:35,985 Beautiful but impossibly dry, 16 00:02:36,121 --> 00:02:39,613 in a good year the Namib gets just five centimetres of rain... 17 00:02:40,759 --> 00:02:43,728 in a bad year, it rains only sand. 18 00:02:55,774 --> 00:02:59,232 But buried within the dunes, there is treasure. 19 00:03:00,779 --> 00:03:02,838 Fragments of dead animals and plants, 20 00:03:02,981 --> 00:03:04,642 swallowed long ago by the sand, 21 00:03:04,783 --> 00:03:08,879 are swept to the surface... offering a crucial lifeline... 22 00:03:31,309 --> 00:03:33,504 Beetles - many different species 23 00:03:33,645 --> 00:03:36,205 have found ways to harvest this bounty. 24 00:03:38,250 --> 00:03:40,047 Along with termites and lizards, 25 00:03:40,252 --> 00:03:44,211 they're the foundations for a delicate chain of life in the Namib. 26 00:03:54,533 --> 00:03:56,228 In this barren sea of sand, 27 00:03:56,368 --> 00:04:00,065 it's harder for larger animals to find enough to eat. 28 00:04:00,272 --> 00:04:04,231 You've got to be a real specialist... like the Namib sand snake. 29 00:04:06,044 --> 00:04:09,639 By sidewinding, it can "swim" its way up the dunes. 30 00:04:15,520 --> 00:04:18,387 But in such an open arena, ambush is tricky... 31 00:04:19,291 --> 00:04:20,758 it's speed that counts... 32 00:04:22,227 --> 00:04:24,923 The wedge-snouted lizard can afford to be blase... 33 00:04:25,864 --> 00:04:27,764 it has a secret weapon... 34 00:04:34,873 --> 00:04:36,340 ...rocket propulsion. 35 00:04:44,249 --> 00:04:46,945 Then it's under the sand as fast as you can... 36 00:04:47,652 --> 00:04:51,053 the best place to escape predators and the sun. 37 00:04:56,261 --> 00:04:58,525 Here in the Namib shelter is sparse... 38 00:04:59,264 --> 00:05:02,233 what little there is, is fiercely protected. 39 00:05:07,772 --> 00:05:11,902 Colonies of dune ants monopolise the tough Namib grasses. 40 00:05:13,378 --> 00:05:14,868 Though aggressive to most invaders, 41 00:05:15,013 --> 00:05:19,177 the ants do tolerate the presence of small sap-sucking bugs 42 00:05:19,251 --> 00:05:22,652 which they get to milk for precious sugary water... 43 00:05:29,794 --> 00:05:33,696 In their grassy home the ants are shaded from the worst of the sun, 44 00:05:33,832 --> 00:05:35,493 but out on the surface of the sand 45 00:05:35,634 --> 00:05:39,195 the temperature can reach a blistering 60 Celsius. 46 00:05:43,074 --> 00:05:46,737 Spoor spiders have an extraordinary survival strategy. 47 00:05:47,579 --> 00:05:48,773 With nowhere to hang their webs, 48 00:05:48,914 --> 00:05:53,214 they spin their silk on the ground, meshing sand grains together. 49 00:05:53,818 --> 00:05:58,016 The result: A mini-blanket which serves as a sunscreen. 50 00:06:20,312 --> 00:06:23,076 But these sandy blankets do more than shelter. 51 00:06:25,550 --> 00:06:28,451 They're beautifully-camouflaged, sticky traps. 52 00:06:31,456 --> 00:06:34,391 Dune ants get most of the food they need on their doorstep, 53 00:06:34,993 --> 00:06:38,759 but to supplement their diet they must also venture out onto the sand. 54 00:06:45,136 --> 00:06:47,764 Their long legs lift them above the baking ground... 55 00:06:47,906 --> 00:06:50,500 to where the temperature is slightly cooler. 56 00:06:55,046 --> 00:06:58,880 But they must still tread carefully... it's a minefield out there. 57 00:07:24,943 --> 00:07:27,070 Pinning the ants to the hot sand surface, 58 00:07:27,212 --> 00:07:31,615 the spiders first cook them to death before dragging them under. 59 00:07:49,234 --> 00:07:52,795 In the Namib even the toughest animals struggle with the heat. 60 00:07:53,238 --> 00:07:55,798 Gemsbok trek to the crests of the highest dunes 61 00:07:55,940 --> 00:07:57,931 to seek relief in the breeze. 62 00:08:12,190 --> 00:08:13,418 With no cloud cover, 63 00:08:13,558 --> 00:08:17,289 solar radiation blasting the desert is intense. 64 00:08:19,197 --> 00:08:24,658 The mid-day sand is so hot it's like a bed of burning coals... 65 00:08:31,209 --> 00:08:34,804 The Namib quickstep... over millions of years, 66 00:08:34,946 --> 00:08:37,005 you learn to keep your claws cool... 67 00:08:50,128 --> 00:08:52,995 Pushed by the wind, the dunes avalanche... 68 00:08:53,932 --> 00:08:56,833 The Namib's residents can't fight the tide... 69 00:09:19,023 --> 00:09:20,718 Though the dunes are unstable, 70 00:09:20,859 --> 00:09:23,953 they provide a home for a remarkable creature. 71 00:09:26,798 --> 00:09:31,360 The trapdoor spider only builds its nest on the top of the steepest dunes... 72 00:09:32,670 --> 00:09:35,468 It's learned to do this because it has a very aggressive enemy. 73 00:09:36,674 --> 00:09:40,041 ...a wasp which relentlessly scours the sand. 74 00:09:44,482 --> 00:09:45,744 Though its eyesight is poor, 75 00:09:45,884 --> 00:09:48,409 the wasp has very sensitive hairs on its legs, 76 00:09:48,553 --> 00:09:51,454 which can pick up the slightest scent of a spider. 77 00:10:10,909 --> 00:10:13,275 When it finds a nest the wasp quickly works out 78 00:10:13,411 --> 00:10:14,844 how deep the burrow is. 79 00:10:15,246 --> 00:10:18,738 If it's shallow the wasp starts digging... for up to two hours. 80 00:10:20,685 --> 00:10:22,880 It's hard work against the slipping sand. 81 00:10:43,374 --> 00:10:44,432 With the spider exposed, 82 00:10:44,576 --> 00:10:49,275 it's now a battle between the wasp's paralysing sting and the spider's jaws. 83 00:10:50,615 --> 00:10:52,845 But the wasp has quicker reflexes. 84 00:10:54,819 --> 00:10:57,845 Cornered, the spider now plays its trump card. 85 00:10:57,989 --> 00:11:01,447 Hurling itself down the dune, it flips into a wheel. 86 00:11:09,567 --> 00:11:14,027 Travelling at over 40 turns a second, it makes a dizzy dash for freedom. 87 00:11:36,461 --> 00:11:39,225 Safe at last. 88 00:11:41,900 --> 00:11:44,528 Back up the dune the wasp is left standing, 89 00:11:44,669 --> 00:11:47,229 chasing the scent of his vanished meal. 90 00:11:55,346 --> 00:11:57,041 Instinct, honed over time, 91 00:11:57,181 --> 00:11:59,149 governs much of the life in the Namib, 92 00:11:59,584 --> 00:12:02,849 but some creatures also have to learn how to conquer these sands, 93 00:12:02,987 --> 00:12:06,013 using knowledge passed down over generations. 94 00:12:19,103 --> 00:12:23,506 African elephants are so resourceful they can survive even here, 95 00:12:23,641 --> 00:12:24,972 in the heart of the desert. 96 00:12:52,103 --> 00:12:54,503 Elephants have remarkable powers of memory. 97 00:12:55,606 --> 00:12:59,565 Though this desert is more than 2 million square kilometres in size, 98 00:12:59,711 --> 00:13:01,770 the hundred or so elephants it supports 99 00:13:01,913 --> 00:13:05,542 know precisely where to find enough to eat and drink. 100 00:13:16,260 --> 00:13:19,957 It takes a lot of food up to three hundred kilos a day 101 00:13:20,098 --> 00:13:22,794 to feed the world's largest land animal... 102 00:13:23,968 --> 00:13:26,198 and all of that from a desert... 103 00:13:30,408 --> 00:13:32,706 But there's one plant here - the Nara 104 00:13:32,844 --> 00:13:35,540 whose roots draw water from deep underground 105 00:13:37,148 --> 00:13:40,117 each year it produces a bumper crop of melons. 106 00:13:40,885 --> 00:13:42,614 Elephants just love them. 107 00:13:58,970 --> 00:14:03,202 Each melon is a valuable package of moisture and seeds. 108 00:14:06,044 --> 00:14:07,875 The plant also benefits from this plunder 109 00:14:08,012 --> 00:14:10,981 as its seeds may be carried for 50 kilometres 110 00:14:11,115 --> 00:14:12,446 in the elephant's stomach, 111 00:14:12,817 --> 00:14:16,446 before being dropped in a pile of fertilising dung. 112 00:14:26,130 --> 00:14:28,189 But the Nara needs more than a passing trade 113 00:14:28,332 --> 00:14:30,596 with elephants to spread its seeds. 114 00:14:33,771 --> 00:14:35,261 Under the cover of darkness, 115 00:14:35,406 --> 00:14:38,603 the nutritious melons also pull in the locals, 116 00:14:38,743 --> 00:14:40,233 like Cape porcupines. 117 00:14:43,848 --> 00:14:48,478 Porcupines may wander up to 15 kilometres a night in search of ripe melons. 118 00:14:49,353 --> 00:14:51,412 They rely on a sharp sense of smell. 119 00:15:15,012 --> 00:15:17,207 Nara melons have a tough outer shell, 120 00:15:17,348 --> 00:15:20,681 but the porcupine's large incisors make short work of them. 121 00:15:26,324 --> 00:15:30,021 Like elephants, porcupines help the Nara to spread its seeds. 122 00:15:33,498 --> 00:15:37,992 By opening up fruits, they also create opportunities for other dune creatures. 123 00:15:43,541 --> 00:15:46,032 Hairy-footed gerbils are hot on their heels. 124 00:15:55,019 --> 00:15:57,351 In the cool of the desert night these little rodents 125 00:15:57,488 --> 00:16:01,322 burn up energy quickly and so must gather food fast... 126 00:16:04,095 --> 00:16:07,030 Though plentiful, the Nara seeds take some plucking... 127 00:16:13,437 --> 00:16:16,167 The gerbils provision for leaner times ahead 128 00:16:16,674 --> 00:16:18,403 but they must also keep alert. 129 00:16:23,781 --> 00:16:27,581 Cape foxes patrol the Nara bushes, looking for gerbils. 130 00:16:35,059 --> 00:16:39,223 Surprisingly the foxes are also partial to the thirst-quenching melons. 131 00:16:47,038 --> 00:16:49,268 But there is a great mystery here. 132 00:16:49,407 --> 00:16:52,069 This is the most extreme African environment... 133 00:16:52,243 --> 00:16:54,473 it may not rain for ten years at a stretch... 134 00:16:54,946 --> 00:16:57,744 so how does the Namib support so much life? 135 00:17:04,488 --> 00:17:07,252 On certain nights the secret is revealed. 136 00:17:19,804 --> 00:17:22,796 Warm, damp air, moving in from the mid-Atlantic 137 00:17:22,940 --> 00:17:27,570 is transformed to fog as it crosses the cold coastal current. 138 00:17:45,229 --> 00:17:49,188 A vast blanket of moisture steadily rolls across the desert. 139 00:18:09,620 --> 00:18:13,056 This veil of mist is the saving grace of the Namib. 140 00:18:21,265 --> 00:18:26,862 Just a few precious drops but enough to allow life to flourish. 141 00:18:30,574 --> 00:18:31,700 A tiny bit of moisture, 142 00:18:31,842 --> 00:18:35,801 a tiny bit of food and tens of millions of years of evolution 143 00:18:35,946 --> 00:18:40,576 are the secrets to success in this harshest of African deserts. 144 00:18:48,359 --> 00:18:52,295 Where else but the Namib would an ingenious little beetle stagger up 145 00:18:52,430 --> 00:18:54,591 the highest dunes on cold mornings, 146 00:18:54,732 --> 00:18:58,498 put its back to the breeze and then stand on its head, 147 00:18:58,636 --> 00:19:01,127 to collect a life-giving drink? 148 00:19:27,198 --> 00:19:30,031 Lmpressive sand dunes dominate the Namib, 149 00:19:30,201 --> 00:19:33,932 but to the south and east is a very different kind of desert 150 00:19:34,071 --> 00:19:37,529 an expanse rocky scrub known as the Karoo. 151 00:19:39,343 --> 00:19:42,938 This desert is as old as the Namib, but here it is mainly rain, 152 00:19:43,080 --> 00:19:45,310 not fog, that drives life. 153 00:19:55,626 --> 00:20:00,063 In the Karoo up to 30 centimetres of rain may fall during winter... 154 00:20:00,231 --> 00:20:04,361 and this extra sprinkle of moisture makes the world of difference. 155 00:20:08,139 --> 00:20:12,473 In spring the desert undergoes a remarkable transformation. 156 00:20:32,363 --> 00:20:33,796 For just a few weeks a year, 157 00:20:33,931 --> 00:20:37,458 the flowers of over 3000 different plant species 158 00:20:37,601 --> 00:20:40,866 turn this desert into the Garden of Africa. 159 00:20:56,854 --> 00:20:59,948 This dazzling variety of colour has evolved over time 160 00:21:00,090 --> 00:21:01,990 for a very special purpose 161 00:21:02,126 --> 00:21:05,254 for plants to seduce their insect pollinators. 162 00:21:09,733 --> 00:21:12,361 Some extraordinary relationships have been forged... 163 00:21:18,075 --> 00:21:20,407 The bright purple blossoms of Lapeirousia 164 00:21:20,544 --> 00:21:25,504 are designed purely to attract a fly with the longest tongue in Africa. 165 00:21:32,990 --> 00:21:36,721 As the fly probes for a sip of nectar in the long floral tubes, 166 00:21:36,861 --> 00:21:39,227 pollen is dabbed onto its forehead. 167 00:21:41,098 --> 00:21:42,224 A smart design... 168 00:21:42,500 --> 00:21:45,799 but on a windy day it's not so easy to hit the target. 169 00:21:51,542 --> 00:21:55,638 Diascia flowers use not nectar but nutritious oils 170 00:21:55,779 --> 00:21:58,680 secreted by glands at the tips of their floral tubes 171 00:21:58,816 --> 00:22:00,113 to tempt pollinators. 172 00:22:04,288 --> 00:22:07,018 Flower and bee in this case a perfect fit 173 00:22:07,224 --> 00:22:09,954 as the insect dips its toes for oil. 174 00:22:18,035 --> 00:22:20,663 Ignited by the rain the flowering of the Karoo touches 175 00:22:20,804 --> 00:22:22,772 the lives of all its inhabitants. 176 00:22:23,340 --> 00:22:25,035 Brandt's whistling rats are quick 177 00:22:25,242 --> 00:22:27,540 to harvest the blossoms around their burrows. 178 00:22:37,288 --> 00:22:40,815 These desert rats time their breeding to the burst of fresh food... 179 00:22:41,725 --> 00:22:42,714 but with snakes around, 180 00:22:42,860 --> 00:22:45,590 mothers can't risk leaving their youngsters at home. 181 00:22:49,266 --> 00:22:50,233 Clinging to her nipples, 182 00:22:50,367 --> 00:22:55,100 they're carried along... a sort of... meals on wheels! 183 00:23:11,388 --> 00:23:14,289 Within a month the spring blooms are finished. 184 00:23:15,025 --> 00:23:16,993 The plants now set their seeds, 185 00:23:17,127 --> 00:23:20,927 taking advantage of the warm summer winds which sweep the desert. 186 00:23:48,659 --> 00:23:51,253 For a while, the Karoo just glows. 187 00:24:07,878 --> 00:24:09,505 But trouble is stirring... 188 00:24:19,923 --> 00:24:25,327 Triggered by the rains, an all-devouring army: Locusts. 189 00:24:33,270 --> 00:24:36,205 Millions emerge from eggs buried in the sand... 190 00:24:36,507 --> 00:24:40,204 gathering into columns which may stretch for 10 kilometres. 191 00:24:48,285 --> 00:24:53,222 At this stage they can't fly - only hop but it doesn't hinder their progress. 192 00:25:00,264 --> 00:25:04,166 These sweeping hordes devastate any fresh growth in their path. 193 00:25:19,116 --> 00:25:24,179 After five weeks of steady munching, the infantry becomes airborne. 194 00:25:28,959 --> 00:25:32,554 These breeding swarms can cover up to 80 kilometres a day... 195 00:25:33,063 --> 00:25:35,896 but only while the food and moisture last. 196 00:25:44,742 --> 00:25:47,404 So how do you define a desert in Africa? 197 00:25:48,045 --> 00:25:52,209 They're places where less than fifty centimetres of rain falls a year. 198 00:25:56,120 --> 00:26:00,420 Neighbouring the Karoo is a desert which gets the maximum - in brief, 199 00:26:00,557 --> 00:26:02,616 but intense summer monsoons. 200 00:26:09,533 --> 00:26:14,596 It's the wettest of all African deserts the great Kalahari. 201 00:26:24,782 --> 00:26:30,186 The sands of the Kalahari cover more of southern Africa than any other desert. 202 00:26:30,821 --> 00:26:34,313 But the higher rainfall here gives it a very distinctive appearance: 203 00:26:36,627 --> 00:26:37,719 More like a savannah, 204 00:26:37,861 --> 00:26:42,264 its sandy ridges carpeted with grasses and a scattering of trees. 205 00:27:06,190 --> 00:27:09,717 In the wet season the Kalahari sands are loosened by the rain, 206 00:27:09,860 --> 00:27:11,691 making them easier to excavate. 207 00:27:12,996 --> 00:27:15,829 Damara molerats, which spend their lives underground, 208 00:27:15,966 --> 00:27:19,333 are now at their most active, hunting for roots and bulbs. 209 00:27:23,707 --> 00:27:28,167 But digging takes 1000 times more energy than travelling on the surface... 210 00:27:28,946 --> 00:27:31,380 ...and even in this greenest of African deserts 211 00:27:31,515 --> 00:27:33,506 the bulbs can be widely spread. 212 00:27:46,396 --> 00:27:49,763 Living on its own, a single molerat would never find enough to eat, 213 00:27:50,100 --> 00:27:53,433 so these small rodents have evolved a co-operative lifestyle, 214 00:27:53,570 --> 00:27:56,630 with up to 40 family members working together. 215 00:28:01,178 --> 00:28:04,409 Like ants or bees, only the queen molerat breeds, 216 00:28:04,548 --> 00:28:07,210 and all her workers are sterile females. 217 00:28:08,085 --> 00:28:09,211 But everybody will benefit 218 00:28:09,353 --> 00:28:13,153 from the extra mouths who'll eventually join in the hunt for food. 219 00:28:16,960 --> 00:28:19,292 Damara molerats are unusual in that their lips 220 00:28:19,429 --> 00:28:21,761 are actually behind their front teeth. 221 00:28:22,566 --> 00:28:25,160 It helps them to avoid swallowing sand while digging. 222 00:28:25,636 --> 00:28:27,399 But it also stops them drinking, 223 00:28:27,537 --> 00:28:30,802 so they must extract all the moisture they need from the bulbs. 224 00:28:43,921 --> 00:28:46,355 During the wet season the bulbs are gathered quickly 225 00:28:46,490 --> 00:28:48,981 before they germinate and lose their goodness. 226 00:28:56,400 --> 00:28:58,459 The molerats store them in special larders 227 00:28:58,602 --> 00:29:01,264 as insurance against the dry months ahead. 228 00:29:06,209 --> 00:29:07,267 Living underground, 229 00:29:07,411 --> 00:29:11,575 molerats are sheltered from the Kalahari's worst extremes of temperature. 230 00:29:13,884 --> 00:29:16,011 We think of deserts as hot places, 231 00:29:16,186 --> 00:29:19,155 but nightly temperatures can fall well below zero. 232 00:29:20,190 --> 00:29:22,249 At dawn meerkats need to soak up 233 00:29:22,392 --> 00:29:25,623 the warmth of the rising sun to get fully active. 234 00:29:38,208 --> 00:29:40,768 The temperature in the Kalahari steadily climbs... 235 00:29:40,911 --> 00:29:43,539 as high as 70 Celsius on the ground. 236 00:29:58,462 --> 00:30:02,865 Meerkats can only tolerate short bursts of activity in the morning and evening. 237 00:30:04,735 --> 00:30:07,431 This means they need to be very efficient at gathering food... 238 00:30:07,738 --> 00:30:11,640 so they quarter their territory, travelling several kilometres a day. 239 00:30:19,850 --> 00:30:23,581 Tasty beetles and scorpions are common in this grassy desert. 240 00:30:24,221 --> 00:30:25,984 But finding them means spending a lot of time 241 00:30:26,123 --> 00:30:27,818 with your head in the sand... 242 00:30:28,458 --> 00:30:31,325 so meerkats are very vulnerable to predators. 243 00:30:33,163 --> 00:30:36,758 To protect the group young males take turns keeping watch. 244 00:30:37,067 --> 00:30:39,297 This frees the others up to keep hunting. 245 00:30:56,353 --> 00:31:00,813 Scorpions have a lethal sting, but meerkats are fast as lightning. 246 00:31:12,602 --> 00:31:17,062 The Kalahari's high levels of rainfall mean food is plentiful year-round... 247 00:31:17,441 --> 00:31:19,306 one reason why this desert can support 248 00:31:19,443 --> 00:31:22,276 more large mammals than any other in the world. 249 00:31:27,250 --> 00:31:30,617 Springbok are the most successful desert antelopes in Africa. 250 00:31:31,688 --> 00:31:35,454 With short thin fur they can easily offload heat by sweating... 251 00:31:36,359 --> 00:31:40,227 the white patterns on their coats help to reflect solar radiation. 252 00:31:43,900 --> 00:31:45,959 And they never need to drink. 253 00:31:46,536 --> 00:31:48,128 They can extract all the moisture they need 254 00:31:48,271 --> 00:31:50,330 from the most meagre desert plants. 255 00:31:56,947 --> 00:32:00,246 But in southern Africa's deserts, there is a lurking challenge. 256 00:32:01,151 --> 00:32:03,381 Cheetahs shadow the springbok herds. 257 00:32:04,754 --> 00:32:06,517 They, too, evolved in the desert. 258 00:32:07,424 --> 00:32:09,051 Thinly-furred and lightly-built, 259 00:32:09,226 --> 00:32:13,185 everything about them is designed to deal with heat and speed. 260 00:32:18,335 --> 00:32:22,328 Cheetahs are sprinters not made for a long distance chase. 261 00:32:23,340 --> 00:32:24,500 So they must get close. 262 00:32:25,709 --> 00:32:27,836 But springbok have keen senses. 263 00:32:31,248 --> 00:32:34,775 True to their name, springbok can leap two metres high. 264 00:32:36,052 --> 00:32:37,747 It's jumping with a purpose: 265 00:32:38,121 --> 00:32:41,648 It signals a warning to the others and confuses attackers. 266 00:33:23,667 --> 00:33:27,899 After such a burst of activity, springbok need to cool down fast. 267 00:33:29,239 --> 00:33:32,299 Here in the Kalahari temperatures can be unbearable, 268 00:33:32,442 --> 00:33:35,536 but large animals can at least find a shady haven 269 00:33:35,679 --> 00:33:38,614 under the broad canopies of camelthorn trees. 270 00:33:47,257 --> 00:33:50,226 For ground squirrels, it's also time to seek shade. 271 00:33:51,261 --> 00:33:53,821 The sand is much cooler just beneath the surface, 272 00:33:53,964 --> 00:33:57,127 so each squirrel digs its own special trench. 273 00:34:10,513 --> 00:34:15,382 For most Kalahari mammals mid-day is siesta time a chance to unwind. 274 00:34:22,392 --> 00:34:25,657 Even the meerkat sentry takes his eye off the job... 275 00:34:44,981 --> 00:34:47,472 But a sociable weaver's work is never done. 276 00:34:48,084 --> 00:34:50,814 They're busy, constructing their own unique shelter. 277 00:34:52,689 --> 00:34:56,648 These giant haystacks can accommodate up to 300 individuals 278 00:34:56,793 --> 00:34:58,624 and can weigh over a tonne. 279 00:35:01,197 --> 00:35:04,462 Because they're occupied year-round, thatching is an endless task. 280 00:35:09,439 --> 00:35:12,169 The nests are a miracle of home-made air conditioning. 281 00:35:12,642 --> 00:35:14,667 Air trapped in the pockets of the thatch acts 282 00:35:14,811 --> 00:35:17,746 as a buffer against extremes of temperature. 283 00:35:18,281 --> 00:35:21,682 In summer it can be 10 degrees Celsius cooler inside. 284 00:35:27,257 --> 00:35:29,782 Teamwork has helped the weavers find a neat solution 285 00:35:29,926 --> 00:35:32,759 to the problems posed by the Kalahari sun. 286 00:35:34,431 --> 00:35:36,797 But some creatures are even better equipped. 287 00:35:42,439 --> 00:35:45,272 Ground squirrels have ready-made parasols. 288 00:35:47,010 --> 00:35:48,773 Under the shadow of their fluffy tails, 289 00:35:48,912 --> 00:35:52,678 they can resume foraging while the sun is still high in the sky. 290 00:36:08,231 --> 00:36:10,563 But the trouble with being active at this time of day 291 00:36:10,700 --> 00:36:15,763 is that so are cold-blooded animals... like the Cape cobra. 292 00:36:19,376 --> 00:36:23,210 Ground squirrels have such quick reflexes they're in no real danger. 293 00:36:23,513 --> 00:36:25,344 But they're still anxious to be rid of it. 294 00:36:30,787 --> 00:36:34,450 They now use their bushy tails to intimidate and frustrate the snake 295 00:36:36,693 --> 00:36:38,684 rather like a red rag to a bull. 296 00:37:14,431 --> 00:37:16,365 It's all too much for the cobra. 297 00:37:16,733 --> 00:37:19,065 Better to just slip away quietly. 298 00:37:24,574 --> 00:37:28,601 As evening draws in, temperatures in the Kalahari can plummet. 299 00:37:29,712 --> 00:37:32,738 Sociable weavers retreat to their insulated nest chambers... 300 00:37:33,349 --> 00:37:35,180 and by snuggling together can sleep, 301 00:37:35,318 --> 00:37:37,650 warm and comfortable, through the night. 302 00:37:49,666 --> 00:37:52,328 Small mammals, like ground squirrels and meerkats, 303 00:37:52,469 --> 00:37:55,233 return to the safety and warmth of their burrows. 304 00:37:57,474 --> 00:38:01,501 Time now to lie low, prepare the warren and bond. 305 00:38:30,540 --> 00:38:33,202 Today, despite its extreme temperatures, 306 00:38:33,343 --> 00:38:36,278 the Kalahari is Africa's mildest desert. 307 00:38:37,447 --> 00:38:39,244 But this hasn't always been so. 308 00:38:40,617 --> 00:38:43,518 Over the last 15 million years Africa's climate 309 00:38:43,653 --> 00:38:47,248 has repeatedly swung from wet to dry and back again 310 00:38:47,390 --> 00:38:50,223 as Ice Ages have come and gone. 311 00:38:57,901 --> 00:39:01,496 At times the Kalahari has been much drier than it is today... 312 00:39:01,638 --> 00:39:04,539 it's sands stretching as far as the equator... 313 00:39:05,174 --> 00:39:08,007 linking it with the largest desert in the world... 314 00:39:08,578 --> 00:39:09,704 the Sahara. 315 00:39:13,082 --> 00:39:15,414 Covering 9 million square kilometres, 316 00:39:15,552 --> 00:39:18,419 the Sahara is so vast the whole of Australia 317 00:39:18,555 --> 00:39:20,750 could comfortably fit into it. 318 00:39:28,331 --> 00:39:32,062 It is bleak... inhospitable... and... 319 00:39:32,201 --> 00:39:35,932 compared to southern Africa's deserts... very new. 320 00:39:39,275 --> 00:39:42,870 Few animals have had time to get to grips with this mighty wilderness... 321 00:39:43,012 --> 00:39:46,038 a place where only the hardiest can get by. 322 00:39:51,487 --> 00:39:54,854 Scimitar-horned oryx are true desert nomads, 323 00:39:54,991 --> 00:39:59,792 wandering for hundreds of miles across the Sahara in search of sparse shrubs. 324 00:40:02,031 --> 00:40:03,430 They've lived long enough in other, 325 00:40:03,566 --> 00:40:08,094 dry regions of Africa to tackle the hardships of this fierce young desert. 326 00:40:19,182 --> 00:40:24,518 Oryx are unusual among antelopes in that females have horns as long as males. 327 00:40:25,521 --> 00:40:28,820 They use these formidable weapons to aggressively deter outsiders 328 00:40:28,958 --> 00:40:32,792 from joining their group, especially when food is limited. 329 00:41:27,850 --> 00:41:31,616 Scimitar-horned oryx are among a handful of tough African mammals 330 00:41:31,754 --> 00:41:33,415 able to cope with the Sahara. 331 00:41:34,323 --> 00:41:36,757 Only one other creature is tougher. 332 00:41:45,702 --> 00:41:48,296 The Arabian camel - not even a native 333 00:41:48,438 --> 00:41:50,599 was domesticated in the deserts of Asia 334 00:41:50,740 --> 00:41:53,937 and brought to North Africa as a means of transport. 335 00:42:03,319 --> 00:42:06,686 In the past, Tuareg nomads used camels to move slaves, 336 00:42:06,823 --> 00:42:10,953 gold and ivory between West Africa and the Mediterranean. 337 00:42:14,097 --> 00:42:18,761 Today their caravans still trade... in salt, dates and millet. 338 00:42:21,838 --> 00:42:25,501 The Sahara has long been a frontier between Asia and Africa. 339 00:42:27,910 --> 00:42:31,641 But there are European pioneers here too red foxes 340 00:42:31,781 --> 00:42:35,877 which scrape a living on the northern fringes of this vast desert. 341 00:42:41,457 --> 00:42:43,721 Though much of the Sahara is uninhabitable, 342 00:42:43,860 --> 00:42:47,125 there are a few special places where life can thrive. 343 00:42:51,267 --> 00:42:54,498 The Ennedi mountains in Tchad harness a little more moisture 344 00:42:54,637 --> 00:42:57,231 from clouds than lower-lying areas 345 00:42:57,340 --> 00:43:00,867 enough to support tiny pockets of savannah. 346 00:43:03,479 --> 00:43:07,176 Here, rock hyraxes survive on the leaves of acacia trees 347 00:43:07,884 --> 00:43:10,375 a scene more typical of the African plains. 348 00:43:13,756 --> 00:43:16,919 These green islands are relics of an older world, 349 00:43:17,059 --> 00:43:21,325 one which is slowly vanishing with the march of the desert sands. 350 00:43:27,537 --> 00:43:31,303 The Sahara as we know it today is only 2000 years old... 351 00:43:31,707 --> 00:43:34,904 the product of a rapidly drying climate in North Africa. 352 00:43:37,446 --> 00:43:40,381 But our ancestors also had a hand in this change... 353 00:43:40,516 --> 00:43:45,385 by over-cultivating marginal lands and intensively grazing livestock. 354 00:43:47,924 --> 00:43:50,256 Before, things were very different. 355 00:43:50,960 --> 00:43:53,952 Try to imagine this land flooded by the ocean, 356 00:43:54,096 --> 00:43:58,396 swathed in forest and savannah... swept by mighty rivers. 357 00:44:26,028 --> 00:44:29,725 Ennedi gorge once fed a vast tributary of the Nile. 358 00:44:31,801 --> 00:44:34,770 Today all that remains are a few precious pools 359 00:44:34,904 --> 00:44:38,533 crucial watering holes for passing caravans of camels. 360 00:44:40,109 --> 00:44:43,408 In just ten minutes of drinking these remarkable animals 361 00:44:43,546 --> 00:44:46,208 can put on a third of their body weight in water... 362 00:44:47,416 --> 00:44:52,115 It's enough to carry them for well over a hundred kilometres to the next oasis. 363 00:44:57,860 --> 00:45:01,125 Arabian camels and nomadic people are the most recent 364 00:45:01,197 --> 00:45:03,825 in a long line of Saharan pioneers. 365 00:45:05,801 --> 00:45:09,965 The history of this great region is told in ancient rock art 366 00:45:10,106 --> 00:45:12,631 glimpses of a vanished world. 367 00:45:14,210 --> 00:45:16,804 Just a few thousand years ago this desert was still wet 368 00:45:16,946 --> 00:45:20,177 enough to support great herds of cattle and goats. 369 00:45:20,683 --> 00:45:24,483 Prey was abundant, and people used horse-drawn chariots, dogs, 370 00:45:24,620 --> 00:45:27,214 bows and arrows in the hunt for food. 371 00:45:33,429 --> 00:45:41,393 Giraffes, elephants, buffalo, lions and rhino roamed across the Sahara. 372 00:45:46,108 --> 00:45:47,837 There were rivers full of fish... 373 00:45:49,512 --> 00:45:51,036 ...even crocodiles. 374 00:45:58,821 --> 00:46:03,849 Today at Ennedi gorge, there are living reminders of that once green Sahara. 375 00:46:06,529 --> 00:46:08,429 In a few isolated oases, 376 00:46:08,564 --> 00:46:11,362 there's still an abundance of aquatic life. 377 00:46:27,216 --> 00:46:28,444 Even more surprising, 378 00:46:28,584 --> 00:46:30,609 is that these communities of fish still 379 00:46:30,753 --> 00:46:34,780 support a dwindling number of Nile crocodiles. 380 00:46:40,229 --> 00:46:43,721 They are the last survivors of a once-healthy population which 381 00:46:43,866 --> 00:46:45,197 over thousands of years 382 00:46:45,267 --> 00:46:48,828 has been left high and dry by the changing climate. 383 00:47:07,823 --> 00:47:12,692 Today just three crocodiles remain too few to continue the line 384 00:47:12,828 --> 00:47:15,319 marooned by hundreds of miles of sand 385 00:47:15,464 --> 00:47:18,490 right in the middle of the mightiest desert on earth. 386 00:47:36,619 --> 00:47:40,282 Africa's deserts are more than just barren expanses... 387 00:47:40,423 --> 00:47:42,288 they're dynamic worlds... 388 00:47:42,425 --> 00:47:44,825 each with its own, unique character... 389 00:47:46,896 --> 00:47:49,865 They are also places of great opportunity... 390 00:47:49,999 --> 00:47:51,626 where given enough time, 391 00:47:51,767 --> 00:47:54,998 a steady climate and a sprinkle of water... 392 00:47:55,137 --> 00:47:56,934 life can flourish. 393 00:47:58,974 --> 00:48:00,339 And it has done so... 394 00:48:00,476 --> 00:48:04,139 in some of the most extraordinary ways imaginable.