0:01:23 > 0:01:26A forest on the lower slopes of the Andes.
0:01:26 > 0:01:31A spectacled bear is looking for a snack.
0:01:58 > 0:02:05One of the problems that faces us and all animals is finding enough to eat.
0:02:05 > 0:02:13Being animals and not plants, we feed on other organisms, and other organisms don't welcome that.
0:02:13 > 0:02:17Animals run away or defend themselves,
0:02:17 > 0:02:22and even plants have surprisingly effective methods of defence.
0:02:22 > 0:02:29I'm in the South American rainforest, the richest proliferation of life on Earth,
0:02:29 > 0:02:34so you might think that here of all places I'd have no difficulty finding food,
0:02:34 > 0:02:38particularly if I was vegetarian. But it's not that simple.
0:02:40 > 0:02:47The woolly spider monkeys up there are taking their first meal of the day.
0:02:47 > 0:02:55This tranquil scene is in fact a battle. The tree defends itself by developing poison in its leaves,
0:02:55 > 0:03:02but when newly sprouted, they are just about edible so the monkeys have to select leaves with care.
0:03:02 > 0:03:07But they're bound to swallow a little poison,
0:03:07 > 0:03:14and now they've had as much as they can tolerate. They move off to find another kind of tree.
0:03:35 > 0:03:42This too has poison in its leaves, but it's a slightly different kind,
0:03:42 > 0:03:47so the monkeys can take a second course,
0:03:47 > 0:03:51providing they continue to be careful.
0:03:56 > 0:04:05Also, leaves are not really very nutritious, and a monkey has to eat great quantities to sustain itself.
0:04:05 > 0:04:08Huge meals require huge stomachs,
0:04:08 > 0:04:15and that means that the monkeys, to be honest, are not the nimblest of movers up in the branches.
0:04:35 > 0:04:41After an hour or so of feeding, the need to digest their vast meals
0:04:41 > 0:04:45demands that they take time off and have a siesta.
0:04:45 > 0:04:49Eating leaves is NOT easy.
0:04:55 > 0:04:59The small red panda of the Himalayas
0:04:59 > 0:05:05is one of the few animals that has beaten the defences of the bamboo.
0:05:05 > 0:05:12Its leaves are not only fibrous but armed with tiny blades of silica so sharp that they can cut flesh.
0:05:12 > 0:05:20But the panda's digestion can cope with them, and the reward is that it has all the bamboo it can eat,
0:05:20 > 0:05:23as so few other animals can eat it.
0:05:31 > 0:05:34Bamboo also grows in Madagascar,
0:05:34 > 0:05:38and here the rare golden bamboo lemur feeds on it.
0:05:38 > 0:05:43It scissors through the coarse outer leaves on the stem
0:05:43 > 0:05:48to reach the marginally softer and more succulent ones within.
0:05:49 > 0:05:56Its preferred choice is not so much leaves as the new shoots that come up through the ground like spears.
0:05:56 > 0:06:01The plant values these shoots and it loads them with cyanide.
0:06:01 > 0:06:06Eating one of these uncooked could kill a man.
0:06:06 > 0:06:14The bamboo lemur can only eat them because its stomach produces juices which neutralise the poison.
0:06:14 > 0:06:16But this ability has a price
0:06:16 > 0:06:23the bamboo lemur can't eat much else. So if the bamboo disappears, so does the lemur.
0:06:25 > 0:06:30The greatest plunderers of leaves, however, are insects.
0:06:30 > 0:06:34They're the most numerous creatures on earth,
0:06:34 > 0:06:41and a high proportion of them as caterpillars or adults eat leaves. The evidence is everywhere.
0:06:44 > 0:06:47Insects are also fussy feeders.
0:06:47 > 0:06:54A female lays her eggs on the kind of plant her caterpillars' digestion can cope with,
0:06:54 > 0:06:59so when they hatch, they find the food they need close at hand.
0:06:59 > 0:07:06They are little more than eating machines a pair of jaws attached to a bag-like gut.
0:07:06 > 0:07:11No complicated wings or sex organs. Those come when they are adults.
0:07:11 > 0:07:14Now it is just munch, munch, munch.
0:07:27 > 0:07:32Plague beetles have a special way of beating a plant's poison.
0:07:32 > 0:07:40Poison is costly to produce, so many plants keep only small stocks to deploy at the point of attack.
0:07:40 > 0:07:46Plague beetles attack in such numbers that the poison is shared between many,
0:07:46 > 0:07:51and each beetle only gets a tiny and tolerable amount.
0:07:57 > 0:08:04It's true that each one only gets a small meal, but as soon as they finish with this plant,
0:08:04 > 0:08:07they move on to another.
0:08:12 > 0:08:16The milkweed invests much more in its defences.
0:08:16 > 0:08:20Its abundant and very poisonous sap, latex,
0:08:20 > 0:08:27is piped along special veins and is immediately available everywhere.
0:08:27 > 0:08:34but this beetle deals with that by puncturing the pipeline that runs along the leaf rib,
0:08:34 > 0:08:37so that the milky latex leaks out.
0:08:45 > 0:08:54As a result, the poison never reaches the end of the leaf, and there the beetle can feed safely.
0:08:54 > 0:09:01The latex also seals a plant's wounds, because it rapidly solidifies in air.
0:09:01 > 0:09:07But since it can't reach here, the beetle has no problem with gummed-up jaws.
0:09:09 > 0:09:13Marmosets also deliberately wound plants.
0:09:13 > 0:09:18They repeatedly gouge grooves in the trunks of trees,
0:09:18 > 0:09:22which then exude resin. Like the milkweed's latex,
0:09:22 > 0:09:30resin seals off the tree's injuries, preventing loss of sap and the entry of infections.
0:09:30 > 0:09:36But unlike latex, it's not poisonous. On the contrary, it's full of sugars,
0:09:36 > 0:09:39and rather good to eat.
0:09:40 > 0:09:43And the marmosets love it.
0:09:43 > 0:09:51So the tree's measures to defend itself have actually resulted in encouraging its injury.
0:10:10 > 0:10:14Not all plants are so uncooperative.
0:10:14 > 0:10:19Some actually encourage animals to feed from them,
0:10:19 > 0:10:26and advertise the fact that they've got food available with brilliant displays, as these poppies do.
0:10:26 > 0:10:31This is not generosity but straightforward self-interest.
0:10:31 > 0:10:37The food they offer is a bribe for the animals to act as couriers.
0:10:37 > 0:10:42They need to have their pollen ferried across to other flowers.
0:10:42 > 0:10:45Pollen, in itself, is edible,
0:10:45 > 0:10:49and bumble bees have a great taste for it.
0:10:53 > 0:10:59Bees have a complex arrangement of combs and brushes on their hind legs
0:10:59 > 0:11:04with which they gather pollen to pack into baskets on their thighs.
0:11:08 > 0:11:11As they move from flower to flower,
0:11:11 > 0:11:16some pollen that was brushed onto their hairy bodies from one flower brushes off on another,
0:11:16 > 0:11:19and the plant's purpose is accomplished.
0:11:25 > 0:11:30Pollen, packed with genetic material, is complex and costly.
0:11:30 > 0:11:34Many flowers offer a cheaper bribe,
0:11:34 > 0:11:38nothing more than sweetened water.
0:11:38 > 0:11:44Nectar is produced from nectaries, usually deep in the heart of the flower.
0:11:44 > 0:11:47Thirsty insects, to reach it,
0:11:47 > 0:11:54have to brush past the stamens, collecting a dusting of pollen on the way.
0:11:56 > 0:12:03In temperate lands, flowers can only be found in spring and summer, when there's no frost.
0:12:03 > 0:12:07So insects that shelter from winter in nests
0:12:07 > 0:12:14have to build up stocks as quickly as they can. They have, in fact, to be "busy as bees."
0:12:15 > 0:12:18In the tropics, on the other hand,
0:12:18 > 0:12:24there are always plants of one kind or another in bloom,
0:12:24 > 0:12:32so nectar is available all year. This vine, Combretum, is particularly generous.
0:12:32 > 0:12:37Almost any animal can get nectar easily when the plant is in flower.
0:12:37 > 0:12:45Many birds which feed mostly on fruit, berries or even insects come to drink from it.
0:12:49 > 0:12:54And so do monkeys. The smaller kinds squirrel monkeys, tamarins, and marmosets
0:12:54 > 0:12:59can clamber right out on to the thinner branches.
0:13:18 > 0:13:26Even the much bigger capuchins which eat fruit, nestling birds, lizards and even small monkeys
0:13:26 > 0:13:29enjoy a sweet drink.
0:13:48 > 0:13:56As the monkeys feed, the stamens brush their fur, and the pollen is on its way to another flower.
0:14:00 > 0:14:04Nectar feeding has its problems.
0:14:04 > 0:14:09This Heliconia flower produces only a little nectar at a time.
0:14:09 > 0:14:16So if a hummingbird comes to feed from one of these blossoms, it has to go elsewhere to get more,
0:14:16 > 0:14:22bringing about the plant's purpose of cross-pollination.
0:14:22 > 0:14:29It takes a little time to produce more nectar, so if the bird returns too soon it may waste a journey,
0:14:29 > 0:14:34but if it's too late, another bird may get the nectar.
0:14:34 > 0:14:38So hummingbirds patrol a whole group of plants,
0:14:38 > 0:14:43visiting each flower in rotation to an accurately timed schedule.
0:14:50 > 0:14:53And he was right on time!
0:15:01 > 0:15:08Hummingbirds are among the very few animals that live almost entirely on nectar.
0:15:08 > 0:15:15Small insects are their only other food, and they have developed special equipment to collect it.
0:15:15 > 0:15:19The wings have joints that enable the bird to beat them with a whirling motion,
0:15:19 > 0:15:21giving it perfect control in the air.
0:15:23 > 0:15:30So it can hover by a flower and insert its beak with absolute precision.
0:15:33 > 0:15:39The long, thread-like tongue flicks in and out 13 times a second.
0:15:46 > 0:15:53But this specialisation means that hummingbirds can feed on almost nothing else
0:15:53 > 0:15:56so they are in the plant's power.
0:15:56 > 0:16:01It may SEEM like the bird is deciding which flower to drink from,
0:16:01 > 0:16:08but you could equally argue that the plant, by controlling the rate at which it produces nectar,
0:16:08 > 0:16:12is dictating the bird's movements.
0:16:12 > 0:16:17Many hummingbirds have a bill which, in its length and curvature,
0:16:17 > 0:16:25exactly matches the shape and dimensions of the particular flower on which they mostly feed.
0:16:25 > 0:16:32The violet sabre-wing's beak fits into the Columnia like a dagger in a scabbard.
0:16:32 > 0:16:40The flower has stamens in precisely the position needed to put a dab of pollen on the bird's forehead.
0:16:45 > 0:16:48This partnership suits Columnia
0:16:48 > 0:16:55because its pollen is not taken by birds who feed on other kinds of flowers and so it isn't wasted.
0:16:55 > 0:17:03It suits the sabre-wing since, because of its unique bill, it has all the Columnia nectar to itself.
0:17:09 > 0:17:11But not quite.
0:17:11 > 0:17:18The mountain gem hummer is waiting for the flower's legal partner to leave.
0:17:24 > 0:17:29Its bill is far too short to reach the nectar as the sabre-wing does.
0:17:29 > 0:17:34With a thrust from its wings, it tries to pierce the flower.
0:17:47 > 0:17:51This time, it holds the flower with its feet.
0:17:53 > 0:17:57It's broken in! Columnia has been burgled!
0:18:00 > 0:18:05Another thief, only too eager to take advantage of a flower.
0:18:06 > 0:18:09Indian langur monkeys.
0:18:11 > 0:18:19The flowers of flame-of-the-forest are protected by being placed at the ends of long, thorny twigs,
0:18:19 > 0:18:25so they're reserved for their particular pollinators, birds.
0:18:25 > 0:18:29But langurs find them very tempting.
0:18:43 > 0:18:48This, of course, is disastrous for the tree.
0:18:48 > 0:18:56Its complex, subtle mechanisms for getting its seeds fertilised evolved over millions of years
0:18:56 > 0:18:59are being chewed to pieces.
0:19:05 > 0:19:09Even the remotest flowers aren't safe,
0:19:09 > 0:19:15for the young babies can clamber right out on to the thinnest branches.
0:19:15 > 0:19:23In the continuous struggle between animals and plants, this round has certainly been lost by the plant.
0:19:32 > 0:19:37In the lush forests of the tropics where flowers bloom all year long,
0:19:37 > 0:19:42animals that feed on nectar can always find a drink somewhere.
0:19:42 > 0:19:47But in other places, where perhaps the winters are bitterly cold,
0:19:47 > 0:19:52or here in the desert where flowers only bloom after brief rains,
0:19:52 > 0:19:59animals that rely on nectar need a way of storing it to last them through the hard times.
0:19:59 > 0:20:07These mulga trees produce nectar on which ants feed and they have the most extraordinary larders.
0:20:11 > 0:20:18The galleries of their nests lie four feet or so below the surface of the ground.
0:20:22 > 0:20:26These golden globes hanging from the roof
0:20:26 > 0:20:30are their storage pots, full of honey.
0:20:30 > 0:20:37Each one is alive an ant with an abdomen expanded to the size of a grape.
0:20:37 > 0:20:45The dark flecks are the plates you see on any ant. The membrane between them is stretched.
0:20:45 > 0:20:53These bloated individuals are almost totally inactive, so they consume little of the honey they hold.
0:20:53 > 0:20:58It is drunk by the busy workers, who, when there is little food above ground,
0:20:58 > 0:21:03come down here and induce the honey-pots to regurgitate it.
0:21:11 > 0:21:18The workers also tend the swollen bodies, keeping them clean.
0:21:20 > 0:21:24During good times, the workers collect nectar
0:21:24 > 0:21:27and take it down to the larders
0:21:27 > 0:21:34to top up the colony's storage jars by feeding it to them, drop by drop.
0:21:52 > 0:21:57The Aborigines who have roamed these deserts for millennia
0:21:57 > 0:22:01have always valued these ants as one of their few sources of sugar.
0:22:01 > 0:22:03And they eat them just as they are.
0:22:07 > 0:22:09Mmm!
0:22:11 > 0:22:18Mmm! It's liquid, warm, and marvellously sweet!
0:22:20 > 0:22:27A few weeks after flowering, many plants tempt animals with another food fruit.
0:22:27 > 0:22:30They have another problem.
0:22:30 > 0:22:33Their seeds are formed, and need to be distributed,
0:22:33 > 0:22:40and by wrapping them in sweet, edible pulp, they recruit lots of animals to do the job.
0:22:43 > 0:22:50The trees dissuade animals from collecting the fruit before the seeds are fully developed
0:22:50 > 0:22:57by not producing the sugars in it until the last moment so unripe fruit tastes bitter
0:22:57 > 0:23:00and is really not worth picking.
0:23:06 > 0:23:11To indicate when it IS, the fruit often changes colour.
0:23:11 > 0:23:19Squirrel monkeys are primarily fruit eaters. They move about in groups of up to 40 or so,
0:23:19 > 0:23:25and they have to wander over a great area to find all the fruit they need.
0:23:25 > 0:23:34Capuchins live in small families, each with its own familiar patch of forest. They eat lots of things.
0:23:34 > 0:23:39But if there's a fruiting tree in their area, they know about it.
0:23:39 > 0:23:47So although squirrel monkeys are frightened of the bigger capuchins, they follow them as they forage.
0:24:02 > 0:24:07There may be food for a capuchin here, a lizard maybe. But no fruit.
0:24:07 > 0:24:11So the squirrel monkey is not interested,
0:24:11 > 0:24:14and must wait.
0:24:19 > 0:24:22The capuchin moves on.
0:24:26 > 0:24:29And the squirrel monkeys follow.
0:24:34 > 0:24:38As the capuchins get near the fruiting tree,
0:24:38 > 0:24:46the squirrel monkeys, perhaps smelling the fruit, scamper ahead to try to get to it first.
0:24:59 > 0:25:02Now they must grab as much as they can
0:25:02 > 0:25:05as quickly as they can.
0:25:18 > 0:25:21The capuchins arrive.
0:25:44 > 0:25:50The squirrel monkeys depart with the tree's seeds inside their stomachs.
0:25:50 > 0:25:55These pass through the monkeys unharmed until, some distance away,
0:25:55 > 0:26:00they are deposited with a convenient dollop of fertiliser.
0:26:00 > 0:26:05Seeds themselves, of course, are packed with nourishment,
0:26:05 > 0:26:12so plants enclose them in shells strong enough to defeat even a mangaby. Victory to the plant.
0:26:14 > 0:26:18But the chimp is so clever, it can crack them.
0:26:20 > 0:26:23Victory to the animal.
0:26:24 > 0:26:31Sharp teeth enable an agouti to chisel into the acorn of a tropical oak.
0:26:34 > 0:26:40In spite of the acorn's armour, it seems the oak has lost the contest.
0:26:40 > 0:26:47But not totally. The oak produces many more acorns than the agouti can eat immediately.
0:26:47 > 0:26:52The rest it carries away and buries for later.
0:27:00 > 0:27:04But an agouti's memory is not infallible.
0:27:04 > 0:27:12Occasionally it forgets about an acorn, which then grows into a new oak. Victory to the plant.
0:27:14 > 0:27:22Perhaps the most extraordinary tool for nut-eating is wielded by a strange Madagascan lemur,
0:27:22 > 0:27:24the aye-aye.
0:27:29 > 0:27:32First it gnaws a hole,
0:27:32 > 0:27:37and then it scoops up the contents with this long, bony probe
0:27:37 > 0:27:45which is, in fact, its finger, but one quite unlike the rest on its hand.
0:27:45 > 0:27:49This curious digit serves equally well for eating a grub.
0:27:49 > 0:27:57The aye-aye uses it to mash up the body hidden in its burrow, and then flicks out the puree.
0:28:00 > 0:28:08The spiny pocket mouse has a double problem. The seed it is gnawing is not only hard-shelled,
0:28:08 > 0:28:13but full of poison. The mouse simply punctures the shell.
0:28:13 > 0:28:18It then tucks it into its cheek and carries it back to its burrow.
0:28:18 > 0:28:22The hole in the shell stimulates the seed to germinate,
0:28:22 > 0:28:27and the tender white shoot which emerges is poison-free!
0:28:36 > 0:28:42The macaw has probably the most powerful nut-cracker of all.
0:28:42 > 0:28:46It can demolish even the most resistant of nuts.
0:28:48 > 0:28:53But many seeds that macaws eat are also filled with poison.
0:28:53 > 0:28:57Yet it doesn't seem to upset them. How do they survive?
0:28:57 > 0:29:01Every day, they fly through the forest
0:29:01 > 0:29:06to dose themselves with a special antidote.
0:29:15 > 0:29:23Macaws usually fly in pairs. Only in such places as this do they assemble in flocks.
0:29:32 > 0:29:35They've come to collect their medicine.
0:29:35 > 0:29:40The regular gathering of birds attracts eagles and other predators.
0:29:40 > 0:29:44So before the macaws come out of the trees,
0:29:44 > 0:29:50they wait for one bird, braver than the rest of them,
0:29:50 > 0:29:53to make the first move.
0:29:53 > 0:29:58There it goes. And this what they're after.
0:29:58 > 0:30:02Kaolin. The soil in this riverbank is rich in it.
0:30:02 > 0:30:10Several kinds of parrots and macaws come here daily from miles around to take the treatment.
0:30:15 > 0:30:22Kaolin combats acidity in the stomach, absorbs and neutralises poisons.
0:30:22 > 0:30:30As a bonus, this clay is rich in calcium and sodium, which is lacking in diets of fruits and nuts.
0:30:56 > 0:31:01So eating plants poses more problems than one might think.
0:31:01 > 0:31:08But eating other animals, even small, defenceless ones, also has its difficulties.
0:31:08 > 0:31:15It's dawn on the east coast of England the middle of winter, and food is very scarce.
0:31:15 > 0:31:20But behind me is a huge and abundantly stocked larder.
0:31:20 > 0:31:27Its doors have been shut for the past three hours, but now the tide is on the turn.
0:31:27 > 0:31:30A horde of hungry animals awaits.
0:31:31 > 0:31:37Tens of thousands of knot and dunlin have assembled on a lagoon
0:31:37 > 0:31:41on the other side of the sand dunes.
0:32:02 > 0:32:09They have sensed that the tide has exposed a mud-bank. Breakfast is served.
0:32:18 > 0:32:26Millions of tiny molluscs lie just below the surface of this mud, and the birds are feeling for them
0:32:26 > 0:32:29with their bills.
0:32:37 > 0:32:44Abundant though the food is out there, collecting it is a very dangerous business.
0:32:44 > 0:32:49It's very exposed on the mud flats, there's nowhere to hide,
0:32:49 > 0:32:54so the birds stick together in tight flocks.
0:32:54 > 0:33:00That way each bird has a thousand eyes ready to spot danger.
0:33:08 > 0:33:12But if that is such a good idea,
0:33:12 > 0:33:15why is this redshank out on its own?
0:33:18 > 0:33:22It's hunting not by touch but by sight.
0:33:22 > 0:33:27It's searching for its favourite food, small shrimp-like crustaceans.
0:33:27 > 0:33:32If they are alarmed by vibrations produced by many moving feet,
0:33:32 > 0:33:37they will disappear into the mud where the redshank can't see them.
0:33:39 > 0:33:46So if a redshank wants to catch this more swiftly moving food, it has to forage by itself,
0:33:46 > 0:33:49despite the risks.
0:33:52 > 0:33:57And if it does become a little alarmed, it just squats.
0:34:00 > 0:34:05Some waters are so rich in food, there is plenty for everybody.
0:34:05 > 0:34:12On this Indian lagoon, there are storks, herons and egrets, openbills and spoonbills.
0:34:12 > 0:34:14Each has its own beak-technique
0:34:14 > 0:34:22with which to catch its favoured prey probing and sieving, scything and stabbing.
0:35:05 > 0:35:10Even parts of the open sea, like this bay in the West Indies,
0:35:10 > 0:35:16have, at certain times, enough fish to attract great flocks of birds.
0:35:29 > 0:35:34Barracuda, among the most ferocious hunters in the sea.
0:35:34 > 0:35:39And they regularly drive shoals of small fish into the bay.
0:36:14 > 0:36:21The pelicans can even tackle shoals which are a foot or two beneath the surface.
0:36:39 > 0:36:44But a pelican can only swallow a fish in its bill
0:36:44 > 0:36:49after draining the water out by opening its beak very slightly.
0:36:49 > 0:36:55And that is the moment the gulls are waiting for.
0:37:16 > 0:37:23Few places on land offer quite the density and richness of animal food
0:37:23 > 0:37:29that can be found in parts of the sea like this.
0:37:29 > 0:37:37But one land animal does swarm in vast numbers, and this tenrec from Madagascar is hunting them.
0:37:43 > 0:37:48They can be sniffed for, but the tenrec's huge ears also help,
0:37:48 > 0:37:53for they make a rustling noise scurrying along their pathways.
0:37:59 > 0:38:04Termites. The juicy soft-bodied workers are largely defenceless.
0:38:04 > 0:38:12But with them come soldiers. This kind squirt noxious chemical sprays from nozzles on their heads.
0:38:27 > 0:38:32The tenrec, with is sensitive nose, can tolerate a certain amount of chemical spray
0:38:32 > 0:38:36but after a while, it just has to come up for air.
0:39:03 > 0:39:11Termites are hugely abundant in the tropics, and many animals collect them whenever possible.
0:39:16 > 0:39:21A small gecko in the deserts of Australia eats little else.
0:39:21 > 0:39:25It's such a fastidious and accurate feeder,
0:39:25 > 0:39:30it can avoid the soldier termites, picking out the workers one by one.
0:39:38 > 0:39:43Of all food-collecting devices, the most ingenious and elegant
0:39:43 > 0:39:49must be the webs of orb spiders, nearly always built by the females.
0:39:49 > 0:39:56One starts by rigging filaments of silk across a flyway used by insects.
0:40:08 > 0:40:11Around the spokes,
0:40:11 > 0:40:15with another kind of silk, she sets a spiral mesh.
0:40:15 > 0:40:19As she secures each section, she twangs it,
0:40:19 > 0:40:22so the glue that coats the silk
0:40:22 > 0:40:26breaks up into a line of sticky beads.
0:40:32 > 0:40:40One of the biggest of these webs, which may be two yards across, is that of the the Nephila spider.
0:40:42 > 0:40:49She is huge. Her legs can span six inches. And she is virtually blind.
0:40:50 > 0:40:54A fly, caught in her web, is quickly seized.
0:40:54 > 0:41:02She rapidly injects it with a venom that will liquify the contents of its body.
0:41:05 > 0:41:13She then wraps it up in silk and parks it on the web to allow the venom to take effect.
0:41:32 > 0:41:35But Nephila's not alone on her web.
0:41:35 > 0:41:40Argyrodes is tiny much smaller even than the fly.
0:41:40 > 0:41:44Nephila could well eat her too.
0:41:44 > 0:41:49She too is blind, but she too feels the vibrations of the struggling fly.
0:41:49 > 0:41:56With what seems like suicidal recklessness, she approaches Nephila feasting on her prey.
0:42:01 > 0:42:10And she too begins to eat food that Nephila not only caught but has conveniently predigested.
0:42:12 > 0:42:15Another capture calls Nephila away.
0:42:22 > 0:42:26Once again she stabs the fly, trusses it up,
0:42:26 > 0:42:31and carries it away to hang on the web. She'll eat that later.
0:42:34 > 0:42:39Argyrodes seems well aware of what's going on.
0:42:48 > 0:42:53As soon as Nephila has finished hanging up her latest catch,
0:42:53 > 0:43:00Argyrodes starts trying to discover its precise position by pulling the web filaments.
0:43:13 > 0:43:18Nephila has returned to finish her first meal.
0:43:23 > 0:43:31Meanwhile, Argyrodes has run a line from the top of the web to the fly, which she is now cutting loose.
0:43:51 > 0:43:57Once the fly is free of the web, she lowers it down.
0:44:09 > 0:44:17The stolen fly is now hanging entirely free. Nephila won't be able to reclaim it now.
0:44:17 > 0:44:22Even so, Argyrodes must get it away to a place
0:44:22 > 0:44:25where she can feed on it in safety.
0:44:25 > 0:44:30Step by step, she heaves it up. Her theft is complete.
0:44:34 > 0:44:39Tropic birds nest on this cliff in Tobago in the West Indies.
0:44:39 > 0:44:47They are magnificent flyers, able to exploit all the air currents with spectacular ease.
0:44:52 > 0:44:57They fish out at sea and every day the parents return to the nest
0:44:57 > 0:45:01with crops full of food for the family.
0:45:15 > 0:45:22Frigates were swift, armed ships which plundered merchantmen and these are frigate-birds.
0:45:25 > 0:45:28The fishing fleet is returning.
0:46:22 > 0:46:29The frigate wasn't trying to kill the tropic bird, only to make it surrender its cargo of fish.
0:46:29 > 0:46:34But it'll have to find another victim.
0:46:34 > 0:46:42The usual tactic of these pirates is to come up astern of a victim and grab its leg or tail.
0:46:49 > 0:46:53It surrenders! There goes its fish.
0:46:55 > 0:46:58And the frigate catches it.
0:47:42 > 0:47:48Frigates aren't always successful, and you can't help wondering
0:47:48 > 0:47:55if it wouldn't be easier to catch fish for themselves, and indeed they often do.
0:47:55 > 0:47:59But they seem positively to enjoy a life of piracy!
0:47:59 > 0:48:06As for the tropic birds well, most of them escape, and at worst they only lose a few fish.
0:48:06 > 0:48:14But it's only a short step between robbing a victim and killing him for the pirate to become a hunter.
0:48:14 > 0:48:21That raises a completely new set of problems, and it's those we'll be looking at in our next programme.
0:49:08 > 0:49:13Subtitles by Anne Morgan BBC Scotland 1990