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