0:00:42 > 0:00:45Meerkats in the Kalahari Desert.
0:00:46 > 0:00:49They spend the night in burrows.
0:00:49 > 0:00:53They find all the food they need on the ground.
0:00:53 > 0:00:56They are swift and expert runners.
0:00:57 > 0:01:00But oddly enough, they also climb
0:01:00 > 0:01:04and they have very good reasons for doing so.
0:01:04 > 0:01:09But first of all, they have to warm up in the early morning sun.
0:01:13 > 0:01:18And once they are warm, it's time for breakfast.
0:01:18 > 0:01:21They find THAT, for the most part, underground.
0:01:21 > 0:01:26If you have your head in the sand, you can't see danger approaching.
0:01:27 > 0:01:32And since they have many predators, someone must always stand guard.
0:01:34 > 0:01:39Sentries aren't very effective if they can't see over the tall grass,
0:01:39 > 0:01:43so to get a really good view, they have to climb as high as they can.
0:01:48 > 0:01:55They don't have particularly long claws, or any other special climbing adaptations.
0:01:55 > 0:02:00Nonetheless, they are surprisingly agile up in the branches.
0:02:00 > 0:02:05They'll climb up just about anything if it gives them extra height.
0:02:05 > 0:02:11An ability to climb is important for a meerkat on sentry duty,
0:02:11 > 0:02:14but for some mammals, it's essential.
0:02:14 > 0:02:18They spend nearly all their time up in the branches.
0:02:18 > 0:02:22If you do that, you really do need special adaptations.
0:02:30 > 0:02:34So, what kind of body does a tree dweller need?
0:02:34 > 0:02:41Grasping hands, long arms to reach distant branches, a long tail, perhaps, to help with balance?
0:02:41 > 0:02:44So, nothing like this, then!
0:02:45 > 0:02:50These are hyrax and, in this safari lodge in Kenya,
0:02:50 > 0:02:54they have acquired a taste for sunbathing.
0:02:54 > 0:02:57Looking at their general body shape,
0:02:57 > 0:03:02you might think they'd be as good in trees as rabbits or guinea pigs.
0:03:02 > 0:03:07But they are surprisingly capable at climbing around in the branches
0:03:07 > 0:03:11and the reason has to do with their special feet.
0:03:11 > 0:03:18Their rubbery soles don't look very special and you can only see how effective they are,
0:03:18 > 0:03:23when their owners stop lazing about in the sun and go off to feed.
0:03:24 > 0:03:27Hyrax have an extremely flexible spine.
0:03:27 > 0:03:33That helps them to scamper up tree trunks with surprising speed.
0:03:36 > 0:03:40But it's their feet that help them stay up there.
0:03:40 > 0:03:44There are special muscles in the middle of each foot
0:03:44 > 0:03:47which pull up the centre of the sole.
0:03:47 > 0:03:53The pads are moist, creating a slight suction which improves their grip, though not all that much.
0:03:57 > 0:04:04Watching them clamber around makes me feel I ought to be standing underneath with a net,
0:04:04 > 0:04:06just in case they fall!
0:04:07 > 0:04:11And what is the reward for this high-wire act?
0:04:11 > 0:04:13Leaves.
0:04:13 > 0:04:17They supply the hyrax with both food and drink.
0:04:17 > 0:04:20Succulent leaves are hard to find on the ground,
0:04:20 > 0:04:27but up in the branches, hyrax can get all they need for the day in a couple of hours.
0:04:27 > 0:04:33So climbing trees is vitally important for a hyrax, even if it does slip every now and then.
0:04:33 > 0:04:37Fortunately, these trees are not very high,
0:04:37 > 0:04:43but elsewhere in the world, there are trees that are ten times as tall as this,
0:04:43 > 0:04:47and there, to be safe, you need something better than rubbery feet.
0:04:47 > 0:04:49Claws should be long.
0:04:49 > 0:04:52And so should tails.
0:04:54 > 0:05:01Tails may not look like climbing aids, but they can be of great help in keeping your balance.
0:05:01 > 0:05:05This is tropical America - and these are coati.
0:05:05 > 0:05:09Much of their food can be found on the ground.
0:05:09 > 0:05:13They climb, primarily, for a different reason...
0:05:13 > 0:05:15safety.
0:05:19 > 0:05:23At the first sign of danger, up they go.
0:05:27 > 0:05:31These days, we too have got specialist tree-climbing gear.
0:05:33 > 0:05:40You start by catapulting a fishing line over a bough, and using that to haul up a rope.
0:05:40 > 0:05:46Then, with clip-on hand-holds - and the help of a counterweight - you can go up, too.
0:05:50 > 0:05:54As in all forests, the trees compete to capture the sunshine.
0:05:54 > 0:05:59Here, in the tropics, they grow very tall in the process.
0:05:59 > 0:06:06And it is up in the canopy, 100 or more feet above the ground, that the real richness of the forest lies.
0:06:11 > 0:06:17A third of the Earth's land is still covered by trees of one kind or another.
0:06:22 > 0:06:27So, not unexpectedly, mammals belonging to very different families
0:06:27 > 0:06:34have managed to acquire the skills and physical adaptations needed to get up into the trees to feed.
0:06:38 > 0:06:43This, I suppose, is what most people would think of as a real forest -
0:06:43 > 0:06:45the tropical rainforest.
0:06:45 > 0:06:51There's a greater variety of food up here than there is anywhere else in the natural world.
0:07:16 > 0:07:20The most obvious source of food up here, of course, are leaves.
0:07:20 > 0:07:23There are certainly enough of them.
0:07:23 > 0:07:27But leaves aren't really very good food.
0:07:27 > 0:07:31They're rather tough, indigestible and don't contain much nutriment.
0:07:35 > 0:07:40One mammal solves that problem not by eating more, but by doing less.
0:07:42 > 0:07:46The sloth moves as if it's powered by the wrong sort of batteries
0:07:46 > 0:07:53and prevents itself from falling off, not by muscle-power, but by hanging from hooks - its claws.
0:07:55 > 0:08:00But there's a lot more than leaves to eat up here, as coatis know.
0:08:12 > 0:08:17If you are fast and agile enough, you can catch birds up here.
0:08:17 > 0:08:22But if you are not, well, some birds make their nests here
0:08:22 > 0:08:27and then eggs and chicks make a good and easy meal.
0:08:36 > 0:08:43And then there are brightly-coloured fruits with fleshy coverings, which are sufficiently good enough to eat
0:08:43 > 0:08:48to persuade animals of all kinds to swallow them and so distribute the seeds.
0:08:51 > 0:08:55The coatis need little encouragement to do that.
0:08:55 > 0:09:01Fruit makes up most of their diet and it is quite a good plan to grab it before it falls
0:09:01 > 0:09:06and comes within reach of other fruit-eaters down on the ground.
0:09:07 > 0:09:12If you are going to stay up here for a long time, you will need to drink.
0:09:12 > 0:09:16That - perhaps surprisingly - is not necessarily a problem.
0:09:16 > 0:09:21Sometimes it's even easier to get a drink up here than it is down below.
0:09:22 > 0:09:27These bromeliads - vase plants - are full of water
0:09:27 > 0:09:32and sometimes these tiny ponds contain insect larvae or even frogs.
0:09:34 > 0:09:37So there's protein as well.
0:09:39 > 0:09:44Woolly monkeys regularly drink from them,
0:09:44 > 0:09:49so they have no need to go down to the ground and hardly ever do so.
0:09:57 > 0:10:02All in all, the larder in the forest canopy is far too rich to ignore
0:10:02 > 0:10:06and many mammals come up here and feed up here.
0:10:06 > 0:10:13But they have very special climbing skills and they are much more at home up here than I am.
0:10:26 > 0:10:29These are proper tree-climbing claws.
0:10:33 > 0:10:36They belong to the sun bear of Indonesia.
0:10:36 > 0:10:43It is a fruit-eater and spends more of its time up in the trees than any other bear.
0:10:44 > 0:10:49Bears don't have tails that might help with their balance.
0:10:49 > 0:10:56But balance isn't a problem for the sun bear because it usually embraces branches rather than runs along them
0:10:56 > 0:10:58and it has very strong forearms.
0:11:02 > 0:11:08And if that's the way you climb, going down is almost as easy as going up.
0:11:31 > 0:11:35The South American tamandua is an anteater.
0:11:35 > 0:11:42Like all anteaters, it has powerful front legs with which to rip open ants' nests,
0:11:42 > 0:11:45and they're a great help in climbing.
0:11:51 > 0:11:56It has a tail and that has become an extremely valuable climbing aid.
0:11:56 > 0:11:59It's prehensile, it can grip.
0:12:13 > 0:12:16It is, in effect, a fifth limb,
0:12:16 > 0:12:23so the tamandua can use its front legs in the same way that its ground-living relatives do.
0:12:28 > 0:12:33Its tail is so well-muscled, it can support the animal's entire weight...
0:12:35 > 0:12:37..which is just as well!
0:12:55 > 0:13:00But there are only so many ant and termite nests in any one tree
0:13:00 > 0:13:05and, sooner or later, the tamandua has to go and look elsewhere.
0:13:09 > 0:13:15That means it has to leave the branches and trundle across the forest floor.
0:13:16 > 0:13:20No big mammal can spend its entire life in a single tree.
0:13:20 > 0:13:24They all have to move to find new sources of food.
0:13:26 > 0:13:32Descending one tree, moving across the ground and climbing up another is one method.
0:13:32 > 0:13:36But there is another, more energy-efficient way
0:13:36 > 0:13:40to cross from one tree to another up there.
0:13:41 > 0:13:46Here in South America, woolly monkeys do that by using their tails
0:13:46 > 0:13:50which are even longer and stronger than the tamandua's.
0:13:57 > 0:14:03A small gap like that might be crossed with the help of a prehensile tail,
0:14:03 > 0:14:07but no tail is going to help with a gap that size.
0:14:07 > 0:14:11From up there, they must look like an abyss -
0:14:11 > 0:14:15but they are the great challenges for any tree dweller.
0:14:19 > 0:14:23Squirrels deal with the problem with dazzling ease.
0:14:23 > 0:14:26They are such lightweights
0:14:26 > 0:14:31that they can race along the thin twigs at the end of the branches
0:14:31 > 0:14:34and they are spectacular jumpers.
0:14:36 > 0:14:39Their powerful hind legs provide the thrust.
0:14:40 > 0:14:43Their long tail acts as a rudder.
0:14:43 > 0:14:49And their shorter front legs serve as shock absorbers to cushion the landing.
0:15:03 > 0:15:08Superb sight enables them to judge distance with great accuracy,
0:15:08 > 0:15:13an essential ability when racing along this three-dimensional highway.
0:15:13 > 0:15:18They are at their most acrobatic during the mating season
0:15:18 > 0:15:21when males pursue the females.
0:15:25 > 0:15:29One male may begin the chase, but others quickly join in.
0:15:38 > 0:15:41Eventually, one wins.
0:15:41 > 0:15:45But as soon as he has claimed his prize, the chase will start again
0:15:45 > 0:15:51and the female may mate with up to eight different males in a day.
0:15:53 > 0:15:55But a gap this size is just too big,
0:15:55 > 0:16:03so a grey squirrel, like a tamandua, often has to come to the ground to visit all the trees in its range.
0:16:09 > 0:16:11A grey squirrel can leap eight feet.
0:16:11 > 0:16:16But there is another tree dweller that can leap much farther than that.
0:16:22 > 0:16:24Although it's no bigger than my hand,
0:16:24 > 0:16:31it could jump from this tree to that tree over there, more than 50 feet away,
0:16:31 > 0:16:33an astonishing distance.
0:16:33 > 0:16:37To see how it does it, we'll have to come back at night.
0:16:41 > 0:16:46Since they have an acute sense of smell and love seeds and nuts,
0:16:46 > 0:16:51maybe these will tempt one down from the tree tops.
0:17:01 > 0:17:03They are flying squirrels.
0:17:04 > 0:17:07How do they fly?
0:17:07 > 0:17:09Just watch.
0:17:21 > 0:17:25Maybe "gliding squirrel" would be a more accurate name.
0:17:25 > 0:17:27They are, nonetheless, astonishing.
0:17:27 > 0:17:33That furry membrane stretching between wrist and ankle makes a most efficient aerofoil.
0:17:43 > 0:17:49Flying squirrels are not territorial and half a dozen can be foraging in the same area of woodland.
0:17:58 > 0:18:03Although this squirrel may have travelled a very long distance
0:18:03 > 0:18:06to get to this valuable source of food,
0:18:06 > 0:18:11it's such an expert glider, it has done so with a minimum of effort.
0:18:11 > 0:18:18And in forests like this one, where food sources are often very widely dispersed,
0:18:18 > 0:18:23the ability to travel fast and far but with very little effort
0:18:23 > 0:18:25is a very valuable ability indeed.
0:18:27 > 0:18:31There are few gaps in these forests that defeat them,
0:18:31 > 0:18:35but to cross really long distances, they do need height.
0:18:38 > 0:18:41They steer partly with their tail
0:18:41 > 0:18:44and partly by moving their outstretched legs,
0:18:44 > 0:18:49so that they vary the tension of their gliding membrane.
0:18:49 > 0:18:51And you can see that they CAN steer
0:18:51 > 0:18:58when one squirrel uses the same take-off point, but glides away to land on different trees.
0:19:16 > 0:19:21Even so, they are not agile enough in the air to escape birds of prey,
0:19:21 > 0:19:26so during the day, they sleep in holes and only emerge when it's dark.
0:19:39 > 0:19:45Gliding from branch to branch was a comparatively small step for tree-living mammals,
0:19:45 > 0:19:49but one group of them made a truly gigantic leap.
0:19:49 > 0:19:52Their arms changed into wings.
0:19:52 > 0:19:57The shoulders, the elbows, the wrists remained much the same,
0:19:57 > 0:20:01but the hand and the fingers changed dramatically.
0:20:18 > 0:20:21Flying foxes - fruit bats in Australia.
0:20:21 > 0:20:25They and their insect-eating cousins are the only mammals
0:20:25 > 0:20:29that have developed true, powered flight.
0:20:33 > 0:20:38They are so big that they can't roost in holes.
0:20:38 > 0:20:45Instead, they sleep out in the open in colonies that may be hundreds of thousands strong.
0:20:45 > 0:20:49The thumb on each hand is free of the wing and has a hooked claw.
0:20:49 > 0:20:52Using that - and the claws on the toes -
0:20:52 > 0:20:57fruit bats are surprisingly nimble, clambering about in the branches.
0:20:58 > 0:21:03Wings may have solved the problem of getting from one tree to another,
0:21:03 > 0:21:06but landing is still a challenge.
0:21:09 > 0:21:14As a fruit bat approaches its chosen perch, it goes into a glide.
0:21:17 > 0:21:21Then it lowers its toes and hooks them onto a branch.
0:21:23 > 0:21:28This is a textbook example of how it's supposed to be done.
0:21:35 > 0:21:39But some perches are more difficult to reach than others.
0:21:46 > 0:21:49Wings need regular grooming.
0:21:49 > 0:21:53They are also very delicate, but small tears quickly heal.
0:21:53 > 0:21:58The wing membrane is among the fastest growing of mammalian tissues.
0:22:01 > 0:22:04They fan their wings to keep cool.
0:22:04 > 0:22:07It can be very hot hanging in the baking sun.
0:22:12 > 0:22:16Take-off requires a special technique.
0:22:16 > 0:22:23Two or three wing beats lift the body to the horizontal, and only then should the feet be unlatched,
0:22:23 > 0:22:25so you don't lose too much height.
0:22:25 > 0:22:32It's hard work, particularly if you are carrying a baby which is a third of your own weight.
0:22:32 > 0:22:37Once in the air, however, fruit bats are extremely strong flyers.
0:22:54 > 0:23:00They can travel great distances - as much as 30 miles, 50 kilometres - in a single night,
0:23:00 > 0:23:03if that's necessary to find food.
0:23:13 > 0:23:17They may have lost a lot of moisture, hanging around in the midday sun,
0:23:17 > 0:23:22so their first call is often to a nearby lake to get a drink.
0:23:22 > 0:23:25They do this in a rather unusual way.
0:23:25 > 0:23:29First, they dip their chests in the water.
0:23:32 > 0:23:37Then they return to their roost and lick the moisture from their fur.
0:23:39 > 0:23:41But there ARE hazards.
0:23:45 > 0:23:46Crocodiles.
0:23:54 > 0:23:58The bats only touch the water for less than a second
0:23:58 > 0:24:03and usually the crocodiles are just not quick enough to catch them.
0:24:03 > 0:24:09But if one miscalculates and comes down on the water, it's a different matter.
0:24:09 > 0:24:15They are surprisingly good swimmers. The worst danger comes when they get to land.
0:24:15 > 0:24:19Being unable to drop into space, as they can from a perch,
0:24:19 > 0:24:21they find it difficult to take off.
0:24:25 > 0:24:29Now the crocodiles have the advantage.
0:24:43 > 0:24:46But a few individuals lost to crocodiles
0:24:46 > 0:24:50makes little impact on the bat colony.
0:24:50 > 0:24:55This roost alone contains a staggering five million.
0:25:33 > 0:25:39Living together in these vast numbers brings several important advantages.
0:25:39 > 0:25:44Flying foxes collect fruit and nectar of many different kinds.
0:25:44 > 0:25:51But knowing which species of fruit tree is in season when is not easy, and some are very unpredictable.
0:25:51 > 0:25:56If a few individual bats return smelling of a particular fruit,
0:25:56 > 0:26:02the news that this food has just come on the market spreads quickly through the whole colony.
0:26:02 > 0:26:07Each bat knows where trees of the various species can be found,
0:26:07 > 0:26:14so the next night, it will go to its own favourite patch to collect the new fruit.
0:26:15 > 0:26:21That is why the whole five million don't follow one another to the same tree.
0:26:29 > 0:26:35Huge wings are good for long-distance flying, but not for manoeuvrability in the air.
0:26:35 > 0:26:40When the bats return in the dawn, hunters are awaiting them.
0:26:44 > 0:26:50Eagles know exactly where a bat's blind spots are and attack from below.
0:27:11 > 0:27:18Powerful though eagles are, fruit bats are big animals and a hit isn't necessarily a kill.
0:27:33 > 0:27:40Raids like these are another reason why an individual bat finds it an advantage to roost in a colony.
0:27:40 > 0:27:44Since it is surrounded by tens of thousands of others,
0:27:44 > 0:27:49there is a good chance that an eagle will pounce on someone else.
0:27:49 > 0:27:54Most colonies have a resident pair of eagles that nest nearby.
0:27:54 > 0:28:01A breeding pair will take about half a dozen bats a day, but that makes little impact on bat numbers.
0:28:01 > 0:28:05Skilled though the eagles are in taking bats on the wing,
0:28:05 > 0:28:11their most successful strategy is to snatch them as they hang in the branches.
0:28:29 > 0:28:33There's another way of getting around in the treetops.
0:28:33 > 0:28:40Instead of having fingers that are greatly elongated and form struts for a wing,
0:28:40 > 0:28:45they can be very small, muscular and give you an extremely powerful grip.
0:28:45 > 0:28:49And the mammals that did that are of particular interest to us
0:28:49 > 0:28:53because they contain our earliest ancestors.
0:28:53 > 0:29:00Most of them are small and nocturnal, and the best way to find them is with a torch like this.
0:29:04 > 0:29:08Highly reflective eyes caught in the torch's beam.
0:29:14 > 0:29:19They belong to a slender loris - a primate, related to the monkeys -
0:29:19 > 0:29:22and it lives in southern India.
0:29:23 > 0:29:28Using a light may be the best way of finding a loris,
0:29:28 > 0:29:33but it's certainly not the best way of seeing how they behave naturally.
0:29:33 > 0:29:37To do that, you have to turn off your lights.
0:29:38 > 0:29:43Infrared cameras give us the rare chance of watching a slender loris
0:29:43 > 0:29:46without disturbing it.
0:29:51 > 0:29:54It's moving so quietly,
0:29:54 > 0:29:57that if it wasn't for this monitor,
0:29:57 > 0:30:02I wouldn't even know that it was just over there.
0:30:07 > 0:30:13Lorisis have elongated thumbs and have lost their index fingers,
0:30:13 > 0:30:18so their grasp is wide enough to encircle quite stout branches.
0:30:18 > 0:30:25They can hold on so tightly that it's almost impossible to detach one from a branch against its will.
0:30:25 > 0:30:29It's the talent for gripping - and a long reach -
0:30:29 > 0:30:35that enables them to deal with that problem of crossing from one tree to another.
0:30:43 > 0:30:46That's what it is after - berries.
0:30:53 > 0:30:56There is another here.
0:30:56 > 0:30:59Lorisis live in small groups of four or five.
0:30:59 > 0:31:03Something seems to have caught this one's eye.
0:31:03 > 0:31:06Perhaps it's our dim infrared light.
0:31:08 > 0:31:13It's frozen, motionless - standard alarm behaviour from a loris.
0:31:13 > 0:31:19It can't move fast, so stands little chance of out-running a predator.
0:31:19 > 0:31:24Instead, it simply stops and hopes that nobody will notice it.
0:31:24 > 0:31:28And now it is off again. It's scent marking.
0:31:28 > 0:31:33That drop of urine will tell any others that it is here.
0:31:33 > 0:31:40It washes its hands in its urine, to leave a trail of smelly footprints behind it.
0:31:40 > 0:31:46Some people think the urine gives the animal a better grip. It's certainly sticky!
0:31:56 > 0:31:58Its eyes both face forwards,
0:31:58 > 0:32:04giving it the stereoscopic vision to judge distance accurately.
0:32:08 > 0:32:12It hunts not by speed, but by stealth.
0:32:13 > 0:32:16Silence - acoustic camouflage -
0:32:16 > 0:32:20enables it to catch its prey unawares.
0:32:22 > 0:32:26Gripping feet - like prehensile tails -
0:32:26 > 0:32:29leave hands free for the pounce.
0:32:33 > 0:32:36That was a grasshopper!
0:32:38 > 0:32:40And now it's found a stick insect.
0:32:45 > 0:32:50This is a mantis. Mantises defend themselves in two ways -
0:32:50 > 0:32:55either by camouflage or aggressive display, like this.
0:32:59 > 0:33:03And neither of them seem much good against a loris!
0:33:11 > 0:33:18Only one creature stands a chance of removing something from the grasp of a loris.
0:33:18 > 0:33:20And that is another loris!
0:33:33 > 0:33:39Africa has got its own similar creature - only a much more lively and athletic one.
0:33:43 > 0:33:46The lesser bushbaby.
0:33:46 > 0:33:50It's probably the most numerous primate in Africa,
0:33:50 > 0:33:54but you seldom see it because it only comes out at night.
0:34:00 > 0:34:04They have a regular pathway through these trees
0:34:04 > 0:34:07which they mark with their urine,
0:34:07 > 0:34:12so you can predict they will go from one tree to the other.
0:34:18 > 0:34:22They're related to lorisis and physically similar -
0:34:22 > 0:34:25with grasping hands,
0:34:25 > 0:34:28stereo vision and large ears.
0:34:33 > 0:34:38But their way of getting around is completely different.
0:34:40 > 0:34:42They hunt not by stealth,
0:34:42 > 0:34:45but by speed.
0:34:48 > 0:34:51They jump 30 times their body length.
0:34:51 > 0:34:54This one is carrying an infant.
0:35:04 > 0:35:09And a leap like that is nothing to a bushbaby!
0:35:12 > 0:35:19Before one takes off, it moves its head from side to side, working out the best place to land.
0:35:19 > 0:35:24That's important, because these trees are very thorny.
0:35:40 > 0:35:47Bushbabies of one species or another have colonised every type of forest in Africa,
0:35:47 > 0:35:54and millions of years ago, ancestral bushbabies even spread beyond the continent.
0:35:58 > 0:36:05Somehow - perhaps on a floating log - they reached the island of Madagascar.
0:36:05 > 0:36:08Here, there were neither predators nor competitors,
0:36:08 > 0:36:13and they diversified into an extraordinary range of species
0:36:13 > 0:36:16which exploit every environment on the island.
0:36:16 > 0:36:19They are the lemurs.
0:36:37 > 0:36:41LEMUR CRIES
0:36:44 > 0:36:49The most specialised of them is the golden bamboo lemur.
0:36:52 > 0:36:55It was discovered only recently,
0:36:55 > 0:36:58and it lives on a part of the bamboo
0:36:58 > 0:37:01that would be fatal to most animals.
0:37:02 > 0:37:04Bamboo pith is full of cyanide.
0:37:04 > 0:37:11The golden lemur eats 12 times as much as would normally kill an animal of its size.
0:37:16 > 0:37:20Other Madagascan plants defend themselves in a different way.
0:37:21 > 0:37:25Didierea is covered with ferocious spines,
0:37:25 > 0:37:31yet it is the chosen home and feeding grounds of another lemur - the sifaka.
0:37:34 > 0:37:37Clambering about here
0:37:37 > 0:37:40requires some very delicate footwork.
0:37:54 > 0:37:58Mother's tail clearly makes a better handhold for a youngster -
0:37:58 > 0:38:03but even at this age, a young sifaka is able to negotiate the spines.
0:38:05 > 0:38:10Collecting didierea leaves and flowers -
0:38:10 > 0:38:12the sifaka's main food -
0:38:12 > 0:38:16looks more hazardous than travelling through its branches.
0:38:28 > 0:38:31But when sifakas decide to move,
0:38:31 > 0:38:34they can travel very fast indeed.
0:38:38 > 0:38:42They use the same method as bushbabies,
0:38:42 > 0:38:44but with such speed and confidence
0:38:44 > 0:38:48that they seem to bounce from trunk to trunk.
0:38:48 > 0:38:52Only in slow motion can you see how accurately they land,
0:38:52 > 0:38:56and how instantaneously they can take off again.
0:38:57 > 0:39:00But given the chance,
0:39:00 > 0:39:03they assess their jumps with care.
0:39:12 > 0:39:16Takeoff starts sideways-on to the line of flight,
0:39:16 > 0:39:20so they have to rotate their bodies in midair.
0:39:21 > 0:39:24Those hind legs, having kicked off,
0:39:24 > 0:39:29have to be swung forward to act as shock absorbers as they make contact.
0:39:40 > 0:39:45Their back feet are long and narrow, with an enormous big toe,
0:39:45 > 0:39:49so that they can lock on to a trunk as soon as they hit it.
0:39:51 > 0:39:54Within seconds, they are off again.
0:40:01 > 0:40:07And a female can even do all this while she is carrying a baby.
0:40:13 > 0:40:18Down on the ground, the method doesn't work quite so well.
0:40:18 > 0:40:22Extremely long legs and very short arms
0:40:22 > 0:40:26make it impossible to run on all fours,
0:40:26 > 0:40:28so, again, it has to be jumping.
0:40:28 > 0:40:33But with no vertical trunk to push away from, the leaps are shorter.
0:40:41 > 0:40:45Back in the trees, they can travel at speed again.
0:40:45 > 0:40:49And they need to, for they have a savage enemy.
0:40:51 > 0:40:54The fossa.
0:40:54 > 0:40:59Its speed through the branches rivals that of the sifakas,
0:40:59 > 0:41:05but its technique is entirely different. It's not a primate with jumping ancestors,
0:41:05 > 0:41:10but a kind of giant mongoose - and it is still a four-footed runner.
0:41:14 > 0:41:19Nonetheless, they are a close match for one another.
0:41:29 > 0:41:32But when it comes to the long jump,
0:41:32 > 0:41:35the sifaka wins.
0:41:36 > 0:41:39A four-footed runner can't match that.
0:41:44 > 0:41:50But it's caught a scent of something else - a female who is ready to mate.
0:41:52 > 0:41:57She has taken up residence in a tree, and there she is holding court.
0:42:07 > 0:42:10She will attract several males.
0:42:10 > 0:42:13There is going to be strong competition.
0:42:34 > 0:42:38An unusually long tail helps in maintaining balance,
0:42:38 > 0:42:42and they manage to negotiate surprisingly thin branches.
0:42:51 > 0:42:57The female decides who to mate with. She drives off those she's not interested in.
0:42:57 > 0:43:00THEY SNARL
0:43:15 > 0:43:18Mating itself is a noisy affair.
0:43:18 > 0:43:21It's made the more difficult,
0:43:21 > 0:43:25by having to balance on a branch while it is going on.
0:43:25 > 0:43:28THEY GRUNT
0:43:38 > 0:43:41THEY CRY AND HISS
0:43:49 > 0:43:52Few animals can match a fossa for speed in the trees,
0:43:52 > 0:43:56and few can descend headfirst, like this.
0:43:56 > 0:44:00The fossa can do so, because it has very flexible ankles
0:44:00 > 0:44:05that allow it to twist its feet to point backwards.
0:44:06 > 0:44:12To find the supreme tree-traveller, we have to go to another continent.
0:44:12 > 0:44:15We have to climb into the canopy
0:44:15 > 0:44:18of the forests of South-East Asia.
0:44:18 > 0:44:21BIRDS SING
0:44:35 > 0:44:42This forest is home to the fastest of all the flightless inhabitants of the canopy in the world.
0:44:42 > 0:44:45It is so swift and so agile,
0:44:45 > 0:44:49that it is capable of catching birds in midair.
0:44:52 > 0:44:54Gibbons.
0:44:54 > 0:44:57Not monkeys, but small apes.
0:45:00 > 0:45:05Their long jump record is about the same as a sifaka - around 40ft -
0:45:05 > 0:45:09but they can move at even greater speed.
0:45:27 > 0:45:32They are such skilled acrobats and can change direction in mid-flow.
0:45:41 > 0:45:45We may be distantly related to the lesser apes,
0:45:45 > 0:45:48but when you watch gibbons like this,
0:45:48 > 0:45:53you realise how ill-equipped we are for a life in the trees.
0:45:53 > 0:45:59Our forearms are too short, our thumbs too big, our shoulders and hips too inflexible
0:45:59 > 0:46:04and our eye-to-hand co-ordination - compared with gibbons - is poor.
0:46:04 > 0:46:08They have one characteristic which we, and all primates, lack -
0:46:08 > 0:46:13that is a ball-and-socket joint in their wrists.
0:46:13 > 0:46:18THAT allows them to perform these fantastic aerial gymnastics.
0:46:20 > 0:46:24Hurtling through the branches hand over hand
0:46:24 > 0:46:29is the gibbons' standard way of getting around.
0:46:31 > 0:46:33Their unique wrist joint
0:46:33 > 0:46:38enables them to rotate the body around the hand and not the shoulder.
0:46:38 > 0:46:40That saves a lot of energy!
0:47:14 > 0:47:18Moving at this speed can be hazardous. Branches may break.
0:47:18 > 0:47:21Jumps may be misjudged.
0:47:21 > 0:47:27Researchers estimate that most gibbons fracture bones at least once in their lives.
0:47:27 > 0:47:31And fatal falls are certainly not unknown.
0:47:36 > 0:47:39Life in the trees is a dangerous business.
0:47:39 > 0:47:43One serious mistake is likely to be your last.
0:47:45 > 0:47:50Mankind's success started when its feet hit the ground
0:47:50 > 0:47:53and it stood up on its hind legs.
0:47:53 > 0:47:57But the coati, hyrax, tamandua and the gibbon
0:47:57 > 0:48:01are proof that there is a very good living to be had up there.
0:48:07 > 0:48:10GIBBONS CRY
0:48:19 > 0:48:26Exactly what goes on high in the canopy of the rainforest, 100-200ft above the ground,
0:48:26 > 0:48:29was, for a long time, a mystery.
0:48:29 > 0:48:34It was so difficult to get up there and move around safely.
0:48:34 > 0:48:38But now, we've got ways of doing just that.
0:48:38 > 0:48:41And the key to them...is this -
0:48:41 > 0:48:45a very, very powerful catapult!
0:48:48 > 0:48:51James Aldred is a catapult expert.
0:48:52 > 0:48:57The first thing you need to do is find your tree!
0:48:57 > 0:49:02'Having found a suitable tree, you need to get the rope up into it.
0:49:02 > 0:49:05'You stretch out a bit of tarpaulin
0:49:05 > 0:49:07'and lay the line out. Fishing line.
0:49:07 > 0:49:11'Play it out there, so it won't snag as it's running,
0:49:11 > 0:49:15'connect a fishing weight, stick it in the catapult and go!
0:49:15 > 0:49:21'Usually, you hit the trunk first time, or get snagged anyhow.
0:49:21 > 0:49:23'Sooner or later, you'll get it.
0:49:24 > 0:49:29'Having got that lightweight line over, you pull up the climbing rope.
0:49:29 > 0:49:33'Anchor that, and you're ready to go up there.'
0:49:33 > 0:49:38The scene is set to get a human up into the rainforest canopy.
0:49:38 > 0:49:41My climb to the canopy
0:49:41 > 0:49:47was only possible after a great deal of preparation.
0:49:49 > 0:49:55James and the team worked in the forest for ten days before the crew and I arrived.
0:49:56 > 0:50:02'We went with an assistant producer and climbing colleague, Phil Hurrell.
0:50:02 > 0:50:08'One of the main hazards in the rainforest was rain! It rained continually from day one.
0:50:08 > 0:50:13'There were storms, winds... Dislodging dead wood from above!
0:50:13 > 0:50:19'The next problem was snakes. We actually found a hognose viper in with our kit.
0:50:19 > 0:50:22'Once you get up there,'
0:50:22 > 0:50:25the last hazard you encounter is primates.
0:50:28 > 0:50:34Howler monkeys are getting rather boisterous, hooting and hollering.
0:50:34 > 0:50:38They are only about this big. They are quite a small primate.
0:50:38 > 0:50:45They are quite intimidating and territorial and did their best to get me out the tree.
0:50:45 > 0:50:50They succeeded! Embarrassing to be seen off by a primate this big,
0:50:50 > 0:50:53but such is the way of life!
0:50:53 > 0:50:57Finding a suitable tree is very time-consuming.
0:51:00 > 0:51:05'Phil and I must have climbed 12-15 trees over those first ten days.'
0:51:20 > 0:51:25We're about four days into our ten-day set-up period,
0:51:25 > 0:51:30but we're having real trouble finding a decent location.
0:51:30 > 0:51:38It's got to be a really fantastic shot - something that really knocks off anything that's gone before.
0:51:40 > 0:51:45'But the next day, I thought I'd found the perfect tree.'
0:51:45 > 0:51:49It's very big, very exposed.
0:51:49 > 0:51:53Each branch is the size of a moderate UK oak tree.
0:51:53 > 0:51:56Big. It's a big tree!
0:51:56 > 0:52:02Having said that, it is an emergent. The view is stunning, but it IS exposed.
0:52:02 > 0:52:04It's very exposed -
0:52:04 > 0:52:09and not somewhere you want to dangle David Attenborough!
0:52:09 > 0:52:14It took us six or seven days to even find a tree.
0:52:14 > 0:52:20When you get up there, you're rewarded with a stunning insight
0:52:20 > 0:52:23to a world no-one else has ever seen.
0:52:23 > 0:52:29You see things which no-one else has seen, or will see. Very privileged.
0:52:32 > 0:52:37Those last days were manic. Phil rigged one tree, I rigged the other.
0:52:37 > 0:52:40'By the skin of our teeth!
0:52:43 > 0:52:48'Once the crew arrives, you get the camera person up first.
0:52:48 > 0:52:51'In this case it was Justine.'
0:52:51 > 0:52:54Nearly there, Justine.
0:52:54 > 0:52:56It looks good from here, actually.
0:52:56 > 0:53:00I'll film you there. Suits me!
0:53:00 > 0:53:03'So, she ran up there. Got settled.
0:53:03 > 0:53:06'Phil was ready to receive David.
0:53:06 > 0:53:10'To get David up, we used a counterbalance system -
0:53:11 > 0:53:17'a rope going up over a pulley, across to another pulley and back to the ground.
0:53:17 > 0:53:22'Someone climbs up one side, with David attached on the other side.
0:53:22 > 0:53:30'They jump off a branch, they come down as a sack of spuds and lift David into position.'
0:53:38 > 0:53:44'The idea was he could move down that cable, parallel to a branch.
0:53:44 > 0:53:49'He could talk about the things you could expect to find in the canopy.
0:53:49 > 0:53:55The other shot was a reveal to show David in context. Nerve-racking!
0:53:55 > 0:54:00We had 16kg of camera going down on a cable which was 100m -
0:54:00 > 0:54:05180ft up - and you've got, you know, David Attenborough at the other end.
0:54:05 > 0:54:12However many safeties you do - it WAS bomb-proof - it does make your heart flutter!
0:54:15 > 0:54:18Is it quite solid down here now?
0:54:19 > 0:54:24David has just been up and down - safely - which is a good thing.
0:54:24 > 0:54:28It's good. I'm feeling rather pleased with myself.
0:54:30 > 0:54:34In recent years, the abundance of tropical forest species
0:54:34 > 0:54:39and the detail of their relationships has been revealed.
0:54:39 > 0:54:45First-hand observation has been vital, but simply seeing the animals in the forest
0:54:45 > 0:54:47is a challenge in itself.
0:54:49 > 0:54:54A colleague, Lesley Ambrose, has studied bushbabies for eight years
0:54:54 > 0:54:58and she only sees the eyes in the trees!
0:54:58 > 0:55:03Studying the animals in the canopy remains a major problem.
0:55:03 > 0:55:07We really know nothing about what they get up to.
0:55:07 > 0:55:14Although you can only see the eyes of these animals and you may never get a close-up view,
0:55:14 > 0:55:20fortunately nearly all bushbabies give a range of very loud calls.
0:55:20 > 0:55:23HIGH-PITCHED CRIES
0:55:23 > 0:55:27Some of the calls are like whistles...
0:55:27 > 0:55:30Some of them are like screams...
0:55:31 > 0:55:35Some of them sound like cross babies crying -
0:55:35 > 0:55:39which is why they are called bushbabies.
0:55:43 > 0:55:49Once we cottoned on to this idea of the differences in the calls,
0:55:49 > 0:55:52we began recording them in earnest.
0:55:52 > 0:55:58We now have a huge library of the sounds of all these different species.
0:55:58 > 0:56:04By recording these sounds, and then by studying them in the laboratory,
0:56:04 > 0:56:07by displaying them on a graph,
0:56:07 > 0:56:12you can understand how they communicate with each other.
0:56:12 > 0:56:16This provides an enormously complex means of communication,
0:56:16 > 0:56:19which we're beginning to unravel.
0:56:19 > 0:56:25Some of the calls - particular sounds they communicate over a long distance -
0:56:25 > 0:56:28seem to be species-specific.
0:56:28 > 0:56:34That's how we recognised the fact that animals that may look the same,
0:56:34 > 0:56:37were totally different species!
0:56:37 > 0:56:42When I started, there were only six species known to science.
0:56:42 > 0:56:48Now, we're approaching 26 species. There's still a few we're not sure about
0:56:48 > 0:56:52and others that we just don't know what they are!
0:56:54 > 0:57:00All of us students have discovered at least one new species of bushbaby,
0:57:00 > 0:57:03during their field work.
0:57:03 > 0:57:07If anyone wants to study these animals in the rainforest,
0:57:07 > 0:57:15it's actually a good opportunity to find out new things that no-one has ever seen before.
0:57:15 > 0:57:19It's surely astonishing that in the 21st century,
0:57:19 > 0:57:23we're STILL discovering new species of mammals.
0:57:23 > 0:57:28Not just any old mammals - primates. The group to which WE belong!
0:57:28 > 0:57:35For, although the tropical forest has been a mammal habitat for many millions of years,
0:57:35 > 0:57:37it's only now, in the 21st century,
0:57:37 > 0:57:42that we humans are truly equipped to reveal its mysteries.
0:57:42 > 0:57:46In the next episode of The Life Of Mammals,
0:57:46 > 0:57:49we meet the monkeys - creatures with colourful appearances
0:57:49 > 0:57:52and even more colourful social lives.
0:58:19 > 0:58:23Subtitles by Dorothy Moore and Susan Mason, BBC Broadcast 2003
0:58:23 > 0:58:26E-mail subtitling@bbc.co.uk