1 00:00:43,687 --> 00:00:50,923 Meerkats in the Kalahari Desert. They spend the night in burrows. 2 00:00:51,087 --> 00:00:54,716 They find all the food they need on the ground. 3 00:00:54,887 --> 00:00:58,402 They're swift and expert runners. 4 00:00:58,567 --> 00:01:05,882 Oddly enough, they also climb - and they have very good reasons for doing so. 5 00:01:06,047 --> 00:01:11,326 First of all, they have to warm up in the early morning sun. 6 00:01:15,287 --> 00:01:19,121 Once they're warm, it's time for breakfast. 7 00:01:19,807 --> 00:01:23,117 They find that, for the most part, underground. 8 00:01:23,287 --> 00:01:27,360 But if you have your head in the sand, you can't see danger approaching. 9 00:01:29,207 --> 00:01:34,645 Since they have many predators, someone must always stand guard. 10 00:01:36,287 --> 00:01:41,281 Sentries aren't very effective if they can't see over the tall grass, 11 00:01:41,447 --> 00:01:46,282 so to get a really good view, they have to climb as high as they can. 12 00:01:52,247 --> 00:01:57,844 They don't have particularly long claws or any other special climbing adaptations. 13 00:01:58,007 --> 00:02:01,602 Nonetheless, they're surprisingly agile up in the branches. 14 00:02:01,767 --> 00:02:06,841 They will climb pretty well anything around, if it gives them extra height. 15 00:02:07,287 --> 00:02:12,645 An ability to climb is important for a meerkat on sentry duty, 16 00:02:12,807 --> 00:02:15,799 but for some mammals, it's essential. 17 00:02:15,967 --> 00:02:19,482 They spend nearly all their time up in the branches, 18 00:02:19,647 --> 00:02:24,084 and if you do that, you really do need special adaptations. 19 00:02:32,327 --> 00:02:35,603 So what kind of body does a tree dweller need? 20 00:02:35,767 --> 00:02:39,885 Grasping hands, long arms to reach distant branches, 21 00:02:40,047 --> 00:02:45,679 a long tail perhaps to help with balance? So nothing like this, then! 22 00:02:47,247 --> 00:02:48,885 These are hyrax, 23 00:02:49,047 --> 00:02:54,167 and in this safari lodge in Kenya they've acquired a taste for sunbathing. 24 00:02:56,287 --> 00:02:59,802 Looking at their general body shape, you might think 25 00:02:59,967 --> 00:03:03,960 that they were about as good in trees as rabbits or guinea pigs. 26 00:03:04,127 --> 00:03:09,155 Actually, they're surprisingly capable of climbing around in the branches, 27 00:03:09,327 --> 00:03:12,637 and the reason has to do with their very special feet. 28 00:03:13,807 --> 00:03:17,197 Their rubbery soles don't look particularly special, 29 00:03:17,367 --> 00:03:19,676 and you can only see how effective they are 30 00:03:19,847 --> 00:03:24,204 when their owners stop lazing about in the sun and go off to feed. 31 00:03:28,087 --> 00:03:30,681 Hyrax have an extremely flexible spine. 32 00:03:30,847 --> 00:03:35,318 That helps them to scamper up the trunks of trees with surprising speed. 33 00:03:38,407 --> 00:03:41,763 But it's their feet that help them stay up there. 34 00:03:42,007 --> 00:03:47,320 Special muscles in the middle of each foot pull up the centre of the sole. 35 00:03:47,487 --> 00:03:51,275 The pads are moist, so this creates a slight suction 36 00:03:51,447 --> 00:03:54,803 which improves their grip, though not all that much. 37 00:04:00,007 --> 00:04:03,795 Watching them clamber around like that makes me feel 38 00:04:03,967 --> 00:04:07,357 I should be standing underneath with a net, in case they fall. 39 00:04:09,287 --> 00:04:15,044 What is the reward for this high wire act? Leaves. 40 00:04:15,207 --> 00:04:18,085 They supply the hyrax with both food and drink. 41 00:04:18,247 --> 00:04:21,364 Succulent leaves are hard to find down on the ground, 42 00:04:21,527 --> 00:04:26,476 but up in the branches, hyrax can get all they need for the day in a couple of hours. 43 00:04:27,527 --> 00:04:31,759 So climbing trees is vitally important for a hyrax, 44 00:04:31,927 --> 00:04:34,646 even if it does slip every now and then. 45 00:04:35,967 --> 00:04:40,643 Fortunately, these trees are not very high, but elsewhere in the world, 46 00:04:40,807 --> 00:04:43,560 there are trees that are ten times as tall as this, 47 00:04:43,727 --> 00:04:48,801 and there, if you are going to be safe, you really need something better than rubbery feet. 48 00:04:49,887 --> 00:04:53,163 Claws should be long and so should tails. 49 00:04:55,687 --> 00:04:58,884 Tails may not look like climbing aids, 50 00:04:59,047 --> 00:05:02,278 but they can be of great help in keeping your balance. 51 00:05:02,967 --> 00:05:07,324 This is tropical America and these are coati. 52 00:05:08,847 --> 00:05:11,725 Much of their food can be found on the ground. 53 00:05:11,887 --> 00:05:16,199 They climb, primarily, for a different reason - safety. 54 00:05:22,407 --> 00:05:24,967 At the first sign of danger, up they go. 55 00:05:29,687 --> 00:05:33,760 These days, we too have got specialist tree-climbing gear. 56 00:05:35,247 --> 00:05:40,605 Start by catapulting a fishing line over a bough, using that to haul up a rope. 57 00:05:41,807 --> 00:05:47,962 Then, with clip-on hand-holds and the help of a counterweight, you can go up too. 58 00:05:51,767 --> 00:05:56,636 As in all forests, the trees compete with one another to capture the sunshine. 59 00:05:56,807 --> 00:06:00,197 Here in the tropics, they grow very tall in the process. 60 00:06:01,647 --> 00:06:08,120 It's up in the canopy, 100 feet above the ground, that the real richness of the forest lies. 61 00:06:11,847 --> 00:06:17,763 A third of the earth's land is still covered by trees of one kind or another. 62 00:06:23,927 --> 00:06:28,921 So, not unexpectedly, mammals belonging to very different families 63 00:06:29,087 --> 00:06:32,875 have managed to acquire the skills and physical adaptations needed 64 00:06:33,047 --> 00:06:36,084 to get up into the trees to feed. 65 00:06:40,047 --> 00:06:47,397 This is what most people would think of as a real forest, the tropical rainforest. 66 00:06:47,567 --> 00:06:53,005 There's a greater variety of food up here than anywhere else in the natural world. 67 00:07:18,607 --> 00:07:22,122 The most obvious source of food up here, of course, are leaves. 68 00:07:22,287 --> 00:07:24,323 There are certainly enough of them. 69 00:07:24,487 --> 00:07:27,797 The fact of the matter is that leaves aren't really very good food. 70 00:07:28,367 --> 00:07:33,157 They are rather tough, indigestible, and actually don't contain much nutriment. 71 00:07:36,647 --> 00:07:41,926 One mammal solves that problem not by eating more but by doing less. 72 00:07:43,447 --> 00:07:47,406 The sloth moves as if it's powered by the wrong sort of batteries 73 00:07:47,567 --> 00:07:50,684 and prevents itself from falling off, not by muscle-power 74 00:07:50,847 --> 00:07:53,407 but by hanging from hooks, its claws. 75 00:07:57,287 --> 00:08:02,486 There's a lot more than leaves to eat up here, as coatis know well. 76 00:08:13,407 --> 00:08:19,164 If you're fast and agile, you can catch birds up here. 77 00:08:19,327 --> 00:08:23,559 If you're not, well, some birds make their nest here, 78 00:08:23,727 --> 00:08:28,960 and then eggs and chicks make a good and easy meal. 79 00:08:37,607 --> 00:08:42,601 And there are brightly-coloured fruits with fleshy coverings, 80 00:08:42,767 --> 00:08:46,555 sufficiently good enough to eat to persuade animals of all kinds 81 00:08:46,727 --> 00:08:49,878 to swallow them and so distribute the seeds. 82 00:08:52,567 --> 00:08:56,003 The coatis need little encouragement to do that. 83 00:08:56,167 --> 00:09:01,560 Fruit makes up most of their diet, and it's good to grab it before it falls 84 00:09:01,727 --> 00:09:06,005 and comes within reach of other fruit-eaters down on the ground. 85 00:09:08,727 --> 00:09:12,845 If you're going to stay up here for a long time, you will need to drink. 86 00:09:13,007 --> 00:09:17,159 That, surprisingly, is not necessarily a problem. 87 00:09:18,887 --> 00:09:23,119 Sometimes it's easier to get a drink up here than it is down below. 88 00:09:23,287 --> 00:09:28,520 These bromeliads, vase plants, are full of water, 89 00:09:28,687 --> 00:09:35,445 and sometimes these tiny ponds contain insect larvae or even frogs. 90 00:09:36,127 --> 00:09:38,163 So there's protein as well. 91 00:09:42,367 --> 00:09:45,200 Woolly monkeys regularly drink from them. 92 00:09:45,367 --> 00:09:51,761 So they have no need to go down to the ground and hardly ever do so. 93 00:09:58,767 --> 00:10:04,319 The larder in the forest canopy is far too rich to ignore 94 00:10:04,487 --> 00:10:07,763 and many mammals come up here and feed up here. 95 00:10:07,927 --> 00:10:14,685 They have special climbing skills and are much more at home here than I am. 96 00:10:27,967 --> 00:10:31,596 These are proper tree-climbing claws. 97 00:10:34,567 --> 00:10:38,958 They belong to the sun bear of Indonesia. It also is a fruit-eater, 98 00:10:39,127 --> 00:10:43,120 and it spends more of its time up in the trees than any other bear. 99 00:10:46,207 --> 00:10:49,517 Bears don't have tails that might help with their balance, 100 00:10:49,687 --> 00:10:52,281 but this isn't a problem to the sun bear, 101 00:10:52,447 --> 00:10:58,716 as it embraces branches rather than run along them and has enormously strong forearms. 102 00:11:03,567 --> 00:11:09,244 If that's the way you climb, going down is almost as easy as going up. 103 00:11:33,527 --> 00:11:36,917 The South American tamandua is an ant-eater, 104 00:11:37,087 --> 00:11:42,957 and like all ant-eaters, it has powerful front legs for ripping open ants' nests, 105 00:11:43,127 --> 00:11:46,597 but they're also a great help in climbing. 106 00:11:52,727 --> 00:11:58,120 It has a tail, and that has become an extremely valuable climbing aid. 107 00:11:58,287 --> 00:12:01,245 It's prehensile - it can grip. 108 00:12:14,687 --> 00:12:17,565 It is, in effect, a fifth limb. 109 00:12:17,727 --> 00:12:23,279 So it can use its front legs in the same way as its ground-living relatives do. 110 00:12:29,647 --> 00:12:35,279 Its tail is so well-muscled, it can support the animal's entire weight. 111 00:12:36,087 --> 00:12:38,760 Which is just as well! 112 00:12:57,127 --> 00:13:01,518 There are only so many ant and termite nests in any one tree, 113 00:13:01,687 --> 00:13:05,680 and sooner or later the tamandua has to go and look elsewhere. 114 00:13:11,367 --> 00:13:16,202 It has to leave the branches and trundle across the forest floor. 115 00:13:17,767 --> 00:13:21,601 No big mammal can spend its entire life in a single tree. 116 00:13:21,767 --> 00:13:24,998 They all have to move to find new sources of food. 117 00:13:27,927 --> 00:13:32,443 Descending one tree, moving across the ground and climbing another 118 00:13:32,607 --> 00:13:37,601 is one method, but there is another, more energy-efficient way - 119 00:13:37,767 --> 00:13:41,362 to cross from one tree to another, up there. 120 00:13:42,847 --> 00:13:47,682 In South America, woolly monkeys do that by using their tails, 121 00:13:47,847 --> 00:13:51,522 which are even longer and stronger than the tamandua's. 122 00:13:59,167 --> 00:14:04,480 A small gap like that might be crossed with the help of a prehensile tail, 123 00:14:04,647 --> 00:14:09,004 but no tail is going to help with a gap of that size. 124 00:14:09,607 --> 00:14:12,804 From up there they must look like an abyss, 125 00:14:12,967 --> 00:14:17,040 but they are the great challenges for any tree-dweller. 126 00:14:22,447 --> 00:14:26,201 Squirrels deal with the problem with dazzling ease. 127 00:14:26,727 --> 00:14:28,524 They're such lightweights, 128 00:14:28,687 --> 00:14:32,521 they can race along the thin twigs at the very far end of the branches. 129 00:14:32,687 --> 00:14:35,121 And they're spectacular jumpers. 130 00:14:37,287 --> 00:14:40,404 Their powerful hind legs provide the thrust. 131 00:14:41,767 --> 00:14:44,964 Their long tail acts as a rudder. 132 00:14:45,087 --> 00:14:50,366 Their shorter front legs serve as shock absorbers to cushion the landing. 133 00:15:04,967 --> 00:15:09,643 Superb sight enables them to judge distance with great accuracy, 134 00:15:09,807 --> 00:15:14,005 an essential ability when racing along this three-dimensional highway. 135 00:15:15,047 --> 00:15:18,164 They are at their most acrobatic during the mating season, 136 00:15:18,327 --> 00:15:21,046 when males start to pursue the females. 137 00:15:26,767 --> 00:15:30,646 One male may begin the chase, but others quickly join in. 138 00:15:39,927 --> 00:15:42,157 Eventually, one wins. 139 00:15:42,327 --> 00:15:46,445 As soon as he's claimed his prize, the chase will start over again 140 00:15:46,607 --> 00:15:51,362 and the female may mate with up to eight different males in a single day. 141 00:15:54,447 --> 00:15:59,885 A gap this size is just too big, so a grey squirrel, like a tamandua, 142 00:16:00,047 --> 00:16:04,643 often has to come to the ground if it's to visit all the trees in its range. 143 00:16:10,887 --> 00:16:13,401 A grey squirrel can leap eight feet, 144 00:16:13,567 --> 00:16:17,799 but there's another tree-dweller that can leap much farther than that. 145 00:16:23,527 --> 00:16:26,041 Although it's no bigger than my hand, 146 00:16:26,207 --> 00:16:29,438 it can jump from this tree to that tree over there, 147 00:16:29,607 --> 00:16:32,280 more than fifty feet away. 148 00:16:32,447 --> 00:16:37,919 An astonishing distance! To see how it does it, we'll have to come back at night. 149 00:16:42,727 --> 00:16:46,606 Since they have an acute sense of smell and love seeds and nuts, 150 00:16:46,767 --> 00:16:52,285 maybe these will tempt one down from the tree tops. 151 00:17:02,487 --> 00:17:04,955 They are flying squirrels. 152 00:17:07,247 --> 00:17:10,922 How do they fly? Just watch. 153 00:17:21,287 --> 00:17:25,439 Maybe ''gliding squirrel'' would be a more accurate name. 154 00:17:25,607 --> 00:17:27,996 They're nonetheless astonishing. 155 00:17:28,167 --> 00:17:33,560 That furry membrane stretching between wrist and ankle makes an efficient aerofoil. 156 00:17:43,327 --> 00:17:46,046 Flying squirrels are not territorial 157 00:17:46,207 --> 00:17:50,723 and as many as half a dozen can be foraging in the same area of woodland. 158 00:18:00,167 --> 00:18:04,763 Although this little squirrel may have travelled a very long distance 159 00:18:04,927 --> 00:18:08,158 in order to get to this valuable source of food, 160 00:18:08,327 --> 00:18:13,640 it's such an expert glider, it's done so with a minimum of effort. 161 00:18:13,807 --> 00:18:19,837 In forests like this, where food sources are often widely dispersed, 162 00:18:20,007 --> 00:18:25,001 the ability to travel fast and far, but with little effort, 163 00:18:25,167 --> 00:18:27,886 is a very valuable ability indeed. 164 00:18:29,527 --> 00:18:32,963 There are few gaps in these forests that defeat them, 165 00:18:33,127 --> 00:18:37,040 but to cross really long distances they do need height. 166 00:18:39,807 --> 00:18:45,598 They steer partly with their tail and partly by moving their outstretched legs 167 00:18:45,767 --> 00:18:49,237 so that they vary the tension of their gliding membrane. 168 00:18:50,167 --> 00:18:52,761 You can see that they can steer 169 00:18:52,927 --> 00:18:55,600 when one squirrel uses the same take-off point 170 00:18:55,767 --> 00:18:59,316 but glides away to land on different trees. 171 00:19:18,407 --> 00:19:23,037 Even so, they're not agile enough in the air to escape birds of prey, 172 00:19:23,207 --> 00:19:27,598 so during the day they sleep in holes and only emerge when it's dark. 173 00:19:40,567 --> 00:19:42,558 Gliding from branch to branch 174 00:19:42,727 --> 00:19:46,003 was a comparatively small step for tree-living mammals, 175 00:19:46,167 --> 00:19:50,524 but there was one group of them that made a truly gigantic leap. 176 00:19:50,687 --> 00:19:54,043 Their arms changed into wings. 177 00:19:54,207 --> 00:19:59,156 The shoulders, elbow and wrists remained much the same, 178 00:19:59,527 --> 00:20:02,803 but the hand and fingers changed dramatically. 179 00:20:20,687 --> 00:20:23,759 Flying foxes - fruit bats in Australia. 180 00:20:23,927 --> 00:20:25,918 They and their insect-eating cousins 181 00:20:26,087 --> 00:20:30,160 are the only mammals that have developed true powered flight. 182 00:20:35,807 --> 00:20:40,961 They're so big that they can't roost in holes. Instead they sleep out in the open 183 00:20:41,127 --> 00:20:44,563 in colonies that may be hundreds of thousands strong. 184 00:20:46,447 --> 00:20:50,076 The thumb on each hand is free of the wing and has a hooked claw. 185 00:20:50,247 --> 00:20:52,477 Using that and the claws on the toes, 186 00:20:52,647 --> 00:20:56,765 fruit bats are surprisingly nimble, clambering about in the branches. 187 00:20:56,847 --> 00:20:59,759 (SCREECHING CHATTER) 188 00:21:01,447 --> 00:21:05,599 Wings may have solved the problem of getting from one tree to another, 189 00:21:05,767 --> 00:21:08,327 but landing is still a challenge. 190 00:21:11,047 --> 00:21:15,962 As a fruit bat approaches its chosen perch, it goes into a glide. 191 00:21:18,687 --> 00:21:22,726 Then it lowers its toes and hooks them onto a branch. 192 00:21:25,327 --> 00:21:29,605 This is a textbook example of how it's supposed to be done. 193 00:21:38,207 --> 00:21:42,359 But some perches are more difficult to reach than others. 194 00:21:47,887 --> 00:21:50,640 Wings need regular grooming. 195 00:21:50,807 --> 00:21:54,482 They are also very delicate, but small tears quickly heal. 196 00:21:54,647 --> 00:21:59,675 The wing membrane is among the fastest-growing of all mammalian tissues. 197 00:22:01,327 --> 00:22:05,115 They also fan their wings to keep themselves cool. 198 00:22:05,287 --> 00:22:09,166 It can be very hot, hanging unprotected in the baking sun. 199 00:22:14,047 --> 00:22:16,959 Take-off too requires a special technique. 200 00:22:17,127 --> 00:22:20,085 Two or three wing beats lift the body to the horizontal 201 00:22:20,247 --> 00:22:22,761 and only then should the feet be unlatched. 202 00:22:22,927 --> 00:22:25,202 That way you don't lose too much height. 203 00:22:25,767 --> 00:22:28,804 It's hard work, particularly if you're carrying a baby 204 00:22:28,967 --> 00:22:31,162 which is a third of your own weight. 205 00:22:33,647 --> 00:22:38,402 Once in the air, fruit bats are extremely strong flyers. 206 00:22:38,847 --> 00:22:41,725 (SCREECHING CHATTER) 207 00:22:55,127 --> 00:22:57,721 They can travel great distances, 208 00:22:57,887 --> 00:23:01,880 as much as thirty miles - fifty kilometres - in a single night, 209 00:23:02,047 --> 00:23:04,880 if that's necessary to find food. 210 00:23:15,287 --> 00:23:19,166 They may have lost a lot of moisture, hanging around in the midday sun, 211 00:23:19,327 --> 00:23:23,366 so their first call is often to a nearby lake to get a drink. 212 00:23:25,447 --> 00:23:30,567 They do this in a rather unusual way. First, they dip their chests in the water. 213 00:23:33,567 --> 00:23:38,595 Then they return to their roost and lick the moisture from their fur. 214 00:23:43,087 --> 00:23:44,759 But there are hazards. 215 00:23:47,527 --> 00:23:49,483 Crocodiles. 216 00:23:58,327 --> 00:24:01,399 The bats only touch the water for less than a second 217 00:24:01,567 --> 00:24:04,843 and usually the crocodiles are not quick enough to catch them. 218 00:24:05,487 --> 00:24:09,116 But if one miscalculates and comes down on the water, 219 00:24:09,287 --> 00:24:11,084 it's a different matter. 220 00:24:12,287 --> 00:24:14,482 They're surprisingly good swimmers. 221 00:24:14,647 --> 00:24:17,036 The worst danger comes when they get to land. 222 00:24:17,207 --> 00:24:20,597 Without being able to drop into space as they can from a perch, 223 00:24:20,767 --> 00:24:23,201 they find it very difficult to get airborne. 224 00:24:27,327 --> 00:24:30,444 Now the crocodiles have the advantage. 225 00:24:45,127 --> 00:24:51,441 But a few individuals lost to crocodiles makes little impact on the bat colony. 226 00:24:52,367 --> 00:24:57,157 This roost alone contains a staggering five million. 227 00:25:36,207 --> 00:25:41,327 Living together in these vast numbers brings several important advantages. 228 00:25:41,487 --> 00:25:45,765 Flying foxes collect fruit and nectar of many different kinds. 229 00:25:45,927 --> 00:25:49,761 Knowing which species of fruit tree is in season at any particular time 230 00:25:49,927 --> 00:25:52,760 is not easy, and some are unpredictable. 231 00:25:53,367 --> 00:25:57,440 If a few individual bats return smelling of a particular fruit, 232 00:25:57,607 --> 00:26:00,201 the news that this food has just come on the market 233 00:26:00,367 --> 00:26:03,086 spreads quickly through the whole colony. 234 00:26:04,527 --> 00:26:08,679 Each bat knows where trees of the various species can be found, 235 00:26:08,847 --> 00:26:14,046 so the next night it'll go to its own favourite patch to collect the new fruit. 236 00:26:17,447 --> 00:26:22,601 That is why the whole five million don't follow one another to the same tree. 237 00:26:31,527 --> 00:26:34,917 Huge wings may be good for long-distance flying, 238 00:26:35,087 --> 00:26:37,760 but they don't give great manoeuvrability in the air, 239 00:26:37,927 --> 00:26:42,478 and when the bats return in the dawn, hunters are awaiting them. 240 00:26:45,487 --> 00:26:50,720 Eagles know where a bat's blind spots are and attack from below. 241 00:27:12,967 --> 00:27:14,559 Powerful though eagles are, 242 00:27:14,887 --> 00:27:19,199 fruit bats are big animals and a hit isn't necessarily a kill. 243 00:27:34,927 --> 00:27:39,079 Raids like these are another reason why an individual bat 244 00:27:39,247 --> 00:27:41,966 finds it an advantage to roost in a colony. 245 00:27:42,127 --> 00:27:44,880 Since it's surrounded by tens of thousands of others, 246 00:27:45,047 --> 00:27:48,562 there's a good chance that an eagle will pounce on someone else. 247 00:27:50,767 --> 00:27:54,999 Most colonies have a resident pair of eagles that nest nearby. 248 00:27:55,487 --> 00:27:58,877 A breeding pair will take half a dozen or so bats a day. 249 00:27:59,047 --> 00:28:02,323 But that still makes little impact on bat numbers. 250 00:28:03,367 --> 00:28:06,325 Skilled though the eagles are in taking bats on the wing, 251 00:28:06,487 --> 00:28:11,845 their most successful strategy is to snatch them as they hang in branches. 252 00:28:32,207 --> 00:28:35,517 There's another way of getting around in the treetops. 253 00:28:35,687 --> 00:28:40,966 Instead of having fingers that are greatly elongated and form struts for a wing, 254 00:28:41,127 --> 00:28:46,804 they can be very small, muscular, and give you an extremely powerful grip. 255 00:28:46,967 --> 00:28:50,926 The mammals that did that are of particular interest to us 256 00:28:51,087 --> 00:28:54,477 because they contain our earliest ancestors. 257 00:28:54,647 --> 00:28:57,320 Most of them are small and nocturnal 258 00:28:57,487 --> 00:29:01,036 and the best way to find them is with a torch, like this. 259 00:29:05,887 --> 00:29:10,119 Highly reflective eyes, caught in the torch's beam. 260 00:29:16,327 --> 00:29:19,364 They belong to a slender loris. 261 00:29:19,527 --> 00:29:22,087 It's a primate, a primitive relation of the monkeys, 262 00:29:22,247 --> 00:29:24,681 and it lives in southern India. 263 00:29:26,207 --> 00:29:30,598 Using a bright light may be the best way of finding a loris, 264 00:29:30,767 --> 00:29:34,601 but it's not the best way of discovering how they behave naturally. 265 00:29:34,767 --> 00:29:38,157 To do that, you have to turn off your lights. 266 00:29:39,407 --> 00:29:42,046 Infra-red cameras give us a rare chance 267 00:29:42,207 --> 00:29:45,995 of watching a slender loris at close quarters without disturbing it. 268 00:29:53,727 --> 00:29:58,437 It's moving so quietly that if it wasn't for this monitor, 269 00:29:58,607 --> 00:30:02,839 I wouldn't even know that it was just over there. 270 00:30:09,167 --> 00:30:14,480 Lorises have greatly elongated thumbs and have lost their index fingers, 271 00:30:14,647 --> 00:30:18,640 so their grasp is wide enough to encircle quite stout branches. 272 00:30:19,247 --> 00:30:23,240 They can hold on so tightly that it's almost impossible 273 00:30:23,407 --> 00:30:26,399 to detach one from a branch against its will. 274 00:30:27,727 --> 00:30:31,003 It's the talent for gripping, together with a long reach, 275 00:30:31,167 --> 00:30:35,206 that enables them to deal with that problem of crossing from one tree to another. 276 00:30:44,687 --> 00:30:47,759 That's what it's after - berries. 277 00:30:54,847 --> 00:30:59,762 There's another here. Lorises live in small groups of four or five. 278 00:31:01,207 --> 00:31:03,926 Something seems to have caught this one's eye. 279 00:31:04,927 --> 00:31:07,395 Perhaps it's our dim infra-red light. 280 00:31:09,927 --> 00:31:12,202 It's frozen motionless. 281 00:31:12,367 --> 00:31:15,040 That's standard alarm behaviour from a loris. 282 00:31:15,207 --> 00:31:19,200 It can't move fast, so it stands little chance of out-running a predator. 283 00:31:19,367 --> 00:31:25,681 Instead, it simply stops and hopes that nobody will notice it. 284 00:31:25,967 --> 00:31:28,003 Now it's off again. 285 00:31:28,927 --> 00:31:31,282 It's scent marking. 286 00:31:31,447 --> 00:31:34,837 That little drop of urine will tell others that it's here. 287 00:31:35,007 --> 00:31:41,526 It washes its hands in urine so that it leaves a trail of smelly footprints. 288 00:31:41,687 --> 00:31:45,566 Some people think that the urine gives the animal a better grip. 289 00:31:45,727 --> 00:31:47,877 It's certainly quite sticky. 290 00:31:57,287 --> 00:32:01,838 Its eyes both face forwards, giving it the stereoscopic vision 291 00:32:02,007 --> 00:32:04,316 necessary to judge distance accurately. 292 00:32:09,687 --> 00:32:13,236 It hunts not by speed but by stealth. 293 00:32:15,087 --> 00:32:21,322 Silence, acoustic camouflage, enables it to catch its prey unawares. 294 00:32:24,367 --> 00:32:29,566 Gripping feet, like prehensile tails, leave hands free for the pounce. 295 00:32:35,167 --> 00:32:37,203 That was a grasshopper. 296 00:32:39,287 --> 00:32:42,120 Now it's found a stick insect. 297 00:32:46,767 --> 00:32:49,235 This is a mantis. 298 00:32:49,407 --> 00:32:51,762 Mantises defend themselves in two ways - 299 00:32:51,927 --> 00:32:55,840 either by camouflage or aggressive display like this. 300 00:33:01,287 --> 00:33:05,075 Neither of them seem much good against a loris. 301 00:33:14,087 --> 00:33:19,081 Only one creature stands a chance of removing something from the grasp of a loris... 302 00:33:19,967 --> 00:33:22,356 and that is another loris. 303 00:33:34,887 --> 00:33:38,357 Africa has got its own similar creature, 304 00:33:38,527 --> 00:33:42,076 only a very much more lively and athletic one. 305 00:33:44,767 --> 00:33:51,002 The lesser bush baby. It's probably the most numerous primate in all Africa, 306 00:33:51,167 --> 00:33:55,126 but you seldom see it because it only comes out at night. 307 00:34:01,567 --> 00:34:09,076 They have a regular pathway through these trees, which they also mark with their urine, 308 00:34:09,247 --> 00:34:13,559 so you can predict that they will go from one tree to the other. 309 00:34:20,887 --> 00:34:23,959 They're related to lorises and physically very similar, 310 00:34:24,127 --> 00:34:29,281 with grasping hands, stereo vision and large ears. 311 00:34:35,527 --> 00:34:39,361 But their way of getting around is completely different. 312 00:34:41,487 --> 00:34:45,685 They hunt not by stealth but by speed. 313 00:34:49,447 --> 00:34:52,519 If pressed, they can jump thirty times their own body length. 314 00:34:53,007 --> 00:34:55,601 This one is carrying an infant. 315 00:35:06,487 --> 00:35:10,526 A leap like that...is nothing to a bush baby. 316 00:35:14,007 --> 00:35:18,080 Before one takes off, it moves its head from side to side, 317 00:35:18,247 --> 00:35:20,238 working out the best place to land. 318 00:35:20,407 --> 00:35:25,162 That's important, because many of these trees are very thorny. 319 00:35:42,407 --> 00:35:44,875 Bush babies of one species or another 320 00:35:45,047 --> 00:35:48,244 have colonised almost every type of forest here in Africa. 321 00:35:48,407 --> 00:35:53,765 Millions of years ago, ancestral bush babies even spread beyond the continent. 322 00:36:00,007 --> 00:36:05,798 Somehow or other, perhaps on a floating log, they reached the island of Madagascar. 323 00:36:05,967 --> 00:36:09,084 Here there were neither predators nor competitors, 324 00:36:09,247 --> 00:36:13,684 and here they diversified into an extraordinary range of species 325 00:36:13,847 --> 00:36:17,476 which now exploit every environment on the island. 326 00:36:17,647 --> 00:36:20,366 They are the lemurs. 327 00:36:39,047 --> 00:36:40,685 (CRIES OUT) 328 00:36:46,607 --> 00:36:50,885 The most specialised of them is the golden bamboo lemur. 329 00:36:53,767 --> 00:36:58,079 It was discovered only recently and it lives on a part of the bamboo 330 00:36:58,247 --> 00:37:01,000 that would be fatal to most other animals. 331 00:37:03,567 --> 00:37:07,276 Bamboo pith is full of cyanide, and the golden lemur 332 00:37:07,447 --> 00:37:11,599 eats twelve times as much as would normally kill an animal of its size. 333 00:37:18,127 --> 00:37:22,200 Other Madagascan plants defend themselves in a different way. 334 00:37:23,127 --> 00:37:26,358 Didierea is covered with ferocious spines, 335 00:37:26,527 --> 00:37:31,442 yet it is the chosen home and feeding grounds of another lemur, the sifaka. 336 00:37:36,047 --> 00:37:40,677 Clambering about here requires some very delicate footwork indeed. 337 00:37:55,847 --> 00:38:00,159 Mother's tail clearly makes a better handhold for a youngster, 338 00:38:00,327 --> 00:38:05,242 but even at this age, a young sifaka is able to negotiate the spines. 339 00:38:07,487 --> 00:38:12,481 Collecting didierea leaves and flowers - and they're the sifaka's main food - 340 00:38:12,647 --> 00:38:15,764 looks even more hazardous than travelling around through its branches. 341 00:38:29,887 --> 00:38:35,439 When sifakas decide to move, they can travel very fast indeed. 342 00:38:40,327 --> 00:38:45,355 They use the same basic method as bush babies but do so with such speed and confidence 343 00:38:45,527 --> 00:38:48,439 that they seem almost to bounce from trunk to trunk. 344 00:38:49,767 --> 00:38:52,998 Only in slow motion can you see just how accurately they land 345 00:38:53,247 --> 00:38:56,523 and how instantaneously they're able to take off again. 346 00:38:59,847 --> 00:39:04,637 But given the chance, they assess their jumps with care. 347 00:39:13,807 --> 00:39:16,640 Take-off has to start sideways-on to the line of flight, 348 00:39:16,807 --> 00:39:20,197 so they have to rotate their bodies in mid-air. 349 00:39:22,727 --> 00:39:25,639 Then those hind legs, having kicked off, 350 00:39:25,807 --> 00:39:30,562 have to be swung forward to act as shock absorbers as they make contact. 351 00:39:41,927 --> 00:39:46,284 Their back feet are long and narrow, with an enormous big toe, 352 00:39:46,447 --> 00:39:49,678 so that they can lock on to a trunk as soon as they hit it. 353 00:39:53,367 --> 00:39:55,927 Then, within seconds, they are off again. 354 00:40:03,327 --> 00:40:07,559 A female can even do all this while she's carrying a baby. 355 00:40:15,727 --> 00:40:19,800 Down on the ground, however, the method doesn't work quite so well. 356 00:40:20,567 --> 00:40:26,164 Extremely long legs and very short arms make it impossible to run on all fours, 357 00:40:26,327 --> 00:40:28,522 so once again it has to be jumping, 358 00:40:28,687 --> 00:40:33,761 but with no vertical trunk to push away from, the leaps are rather shorter. 359 00:40:42,807 --> 00:40:46,277 Back in the trees, they can travel at speed again, 360 00:40:46,447 --> 00:40:50,440 and they need to, for they have a savage enemy. 361 00:40:53,127 --> 00:40:55,595 The fossa. 362 00:40:56,967 --> 00:41:03,281 Its speed through the branches rivals that of the sifakas, but its technique is entirely different, 363 00:41:03,447 --> 00:41:07,804 for it's not a primate, with jumping ancestors, but a kind of giant mongoose, 364 00:41:07,967 --> 00:41:11,004 and it's still a four-footed runner. 365 00:41:15,887 --> 00:41:19,243 Nonetheless, they're a close match for one another. 366 00:41:30,927 --> 00:41:35,364 But when it comes to the long jump, the sifaka wins. 367 00:41:37,687 --> 00:41:40,759 A four-footed runner can't match that. 368 00:41:47,207 --> 00:41:53,362 It's caught the scent of something else, a female who is ready to mate. 369 00:41:53,487 --> 00:41:57,924 She's taken up residence in a tree and there she's holding court. 370 00:42:09,487 --> 00:42:14,402 She will attract several males. There's going to be strong competition. 371 00:42:35,727 --> 00:42:39,640 An unusually long tail helps in maintaining balance, 372 00:42:39,807 --> 00:42:43,277 and they manage to negotiate surprisingly thin branches. 373 00:42:53,007 --> 00:42:55,282 The female will decide who she mates with, 374 00:42:55,447 --> 00:42:58,837 and drives off those in whom she is not interested. 375 00:42:59,007 --> 00:43:02,158 (SQUAWKS AND SCREECHES) 376 00:43:17,047 --> 00:43:22,075 Mating itself is a noisy affair and is made more difficult, doubtless, 377 00:43:22,247 --> 00:43:25,284 by having to balance on a branch while it's going on. 378 00:43:25,447 --> 00:43:28,757 (CRIES AND GROANS) 379 00:43:35,927 --> 00:43:38,805 (CRIES CLIMAX) 380 00:43:50,407 --> 00:43:54,002 Few other hunting animals can match a fossa for speed through the treetops, 381 00:43:54,167 --> 00:43:57,762 and few can descend head-first like this. 382 00:43:58,007 --> 00:44:01,841 The fossa manages to do so because it has very flexible ankles 383 00:44:02,007 --> 00:44:05,886 that allow it to twist its feet round to point backwards. 384 00:44:08,167 --> 00:44:13,719 To find the supreme tree-traveller, we have to go to another continent. 385 00:44:13,887 --> 00:44:19,086 We have to climb into the canopy of the forests of south-east Asia. 386 00:44:19,247 --> 00:44:22,284 (CREATURES CALL OUT) 387 00:44:35,247 --> 00:44:43,518 This forest is home to the fastest of all the flightless inhabitants of the canopy in the world. 388 00:44:43,687 --> 00:44:50,081 It's so swift and so agile, it's capable of catching birds in mid-air. 389 00:44:53,447 --> 00:44:57,918 Gibbons. Not monkeys, but small apes. 390 00:45:01,767 --> 00:45:06,602 Their long jump record is about the same as a sifaka, around 40 feet, 391 00:45:06,767 --> 00:45:09,440 but they can move at even greater speed. 392 00:45:26,927 --> 00:45:32,445 They're such skilled acrobats that they can change direction in mid-flow. 393 00:45:43,847 --> 00:45:50,161 We may be distantly related to the lesser apes, but when you watch gibbons up in the branches 394 00:45:50,327 --> 00:45:54,286 you realise how ill-equipped we are for a life in the trees. 395 00:45:54,447 --> 00:46:00,204 Our forearms are too short, our thumbs are too big, our shoulders and hips too inflexible 396 00:46:00,367 --> 00:46:04,997 and our eye-to-hand coordination, compared with gibbons, is very poor. 397 00:46:05,167 --> 00:46:09,957 They have one characteristic which we - and indeed all other primates - lack; 398 00:46:10,127 --> 00:46:14,803 that is to say, a ball and socket joint in their wrists. 399 00:46:14,967 --> 00:46:19,961 It's that that allows them to perform these fantastic aerial gymnastics. 400 00:46:22,167 --> 00:46:28,845 Hurtling through the branches hand over hand is the gibbons' standard way of getting around. 401 00:46:33,047 --> 00:46:39,282 Their unique wrist joint enables them to rotate the body around the hand and not the shoulder, 402 00:46:39,447 --> 00:46:41,881 and that saves a lot of energy. 403 00:47:15,887 --> 00:47:22,235 But travelling at this speed can be hazardous. Branches may break, jumps may be misjudged. 404 00:47:22,407 --> 00:47:28,642 Researchers estimate that most gibbons fracture their bones at least once in their lives. 405 00:47:28,807 --> 00:47:32,277 And fatal falls are certainly not unknown. 406 00:47:37,247 --> 00:47:45,040 Life in the trees is a dangerous business. One serious mistake is likely to be your last. 407 00:47:48,687 --> 00:47:54,842 Mankind's success started when its feet hit the ground and it stood up on its hind legs. 408 00:47:55,007 --> 00:47:58,283 But the coati and the hyrax, the tamandua and the gibbon 409 00:47:58,447 --> 00:48:02,565 are proof that there is a very good living to be had up there. 410 00:48:09,007 --> 00:48:11,157 (WARBLED CRY)