Nut cracking is a complicated business,
and involves some of the most advanced tool-using techniques
practised by any animal.
It's no use just bashing a stick on the ground.
You have to have a decent anvil.
The anvil is almost always the root of a tree.
Eventually, the time comes when, at last, you get the hang of things.
For chimpanzees, acquiring adult skills is a gradual process,
but that is not the case for most animals.
For these baby albatross on the Leeward Islands in the Pacific,
the ending of childhood is brutally abrupt.
Within the next few days, they must fly
and quickly become as accomplished in the air as their parents,
who fly so effortlessly above them.
The best they can do to prepare is to strengthen their breast muscles
by beating their wings.
If they don't get it right first time,
the results could be catastrophic -
in the shallows, dark shapes have appeared.
Tiger sharks.
Every year, at this precise time, they appear from nowhere.
For the bats too, in the cave in Texas,
childhood is coming to an end.
The babies are now over a month old,
and the time is coming for their mothers to join the males in Mexico
and take their babies with them.
For the past few days,
many babies have been going on practice flights within the cave,
but now some of them are accompanying the adults
as they fly out into the open sky.
But they're far from expert fliers.
Here's one that has crash landed within a few yards of the cave.
When he was in the cave, he was very safe -
about one in a hundred babies die in there -
but out here, he's surrounded by danger.
Of the million bats that were born five weeks ago in there,
three quarters will be dead before they're adult.
So for this little creature,
the trials of life really are just starting. Good luck to you.
A forest on the lower slopes of the Andes.
A spectacled bear is looking for a snack.
One of the problems that faces us and all animals
is finding enough to eat.
Being animals and not plants, we only feed on other living organisms
and, by and large, other living organisms don't welcome that.
Animals run away or defend themselves
and even plants have surprisingly effective ways of preventing anyone from stealing their leaves.
I'm in the South American rainforest -
the richest proliferation of life on Earth -
so you might think that here I'd have no difficulty in finding food,
particularly if I was prepared to be vegetarian.
But it's not as simple as that.
These woolly spider monkeys are taking their first meal of the day.
It might seem to be a gentle, peaceful scene,
but, in fact, it's a battleground.
The tree defends itself by developing poison in its leaves,
but when newly-sprouted, they're just edible,
so the monkeys have to select which they eat with great care.
Even with great discrimination, they will swallow a little poison,
and now they've had as much as they can tolerate.
They move off and find another kind of tree.
This too has poison in its leaves, but it's a slightly different kind,
so the monkeys can take a second course of their meal,
providing they continue to be careful.
Another drawback to eating leaves is that they're not very nutritious,
and the monkey has to eat great quantities to sustain itself.
Huge meals require huge stomachs to hold them,
and that means that the monkeys are not the most nimble of movers
up in the branches.
After an hour or so of feeding,
the need to digest their vast meals demands that they take time off
and have a siesta.
Eating leaves is not easy.
The greatest plunderers of leaves, however, are insects.
They're the most numerous creatures on Earth
and a high proportion of them - as caterpillars or adults - eat leaves.
The evidence is everywhere.
But insects too must take steps to avoid a plant's defences.
These plague beetles are attacking a plant
that can pump poison into its leaves.
Since such poison is costly to produce,
many plants only keep small stocks
and deter grazers by rapidly deploying it to the point of attack.
But plague beetles descend on a plant in such numbers
that its poison is shared between many,
and each beetle only gets a tiny and tolerable amount.
It's true that each one only gets a small meal,
but as soon as they've finished with this plant,
they move on to another.
The milkweed invests much more in its defences.
Its abundant and very poisonous sap - latex -
is piped along special veins, and is immediately available everywhere.
But this beetle has worked out how to deal with that.
It punctures the pipeline running along the leaf rib,
so that the milky latex leaks out.
As a result, the poison never reaches the end of the leaf,
and there the beetle can feed in safety.
Not all plants are so uncooperative.
Some actually encourage animals to come and feed from them,
and advertise the fact they've got food with brilliant displays -
as these poppies are doing.
This is not, of course, generosity on their part, but self-interest.
The food they have to offer is a bribe
to persuade the animals to act as couriers.
They need to have their pollen ferried across to other flowers.
Pollen in itself is edible.
Bumble-bees have a great taste for it.
Bees have a complex arrangement of cones and brushes on their hind legs
with which they gather pollen
and pack it into baskets on their thighs.
As they move from flower to flower,
the pollen that brushes onto their bodies on one flower
brushes off on another, and the plant's purpose is accomplished.
Pollen, packed with genetic material,
is a complex and expensive commodity,
and many flowers offer a cheaper bribe -
nothing more than sweetened water.
Nectar.
The plant produces it from nectaries usually in the heart of the flower,
so that thirsty insects, to reach it,
have to brush past the stamens, collecting a dusting of pollen.
Nectar feeding has its problems.
A heliconia flower, like this one,
produces only a little nectar at a time.
So if a hummingbird comes to feed from here,
it has to go elsewhere to get more,
so bringing about the heliconia's purpose of cross pollination.
And it takes a little time for the heliconia to produce more nectar,
so if the hummingbird comes back too soon it's wasted its journey;
too late, and another bird may have stolen the nectar.
As a consequence, hummingbirds patrol a group of these plants,
visiting each flower in strict rotation
to an accurately-timed schedule.
The proprietor of this plant should be here any minute.
And he was right on time.
Hummingbirds are among the few animals
that live almost entirely on nectar - they also eat small insects -
and they've developed special equipment to collect it.
The wings have joints that enable them to beat with a whirling motion,
giving perfect control in the air.
So it can hover in front of a flower
and insert its beak with absolute precision.
The tongue is long and thread-like,
and flicks in and out thirteen times a second.
But this specialisation
means that hummingbirds can feed on almost nothing else,
and that puts them in the plant's power.
It may seem that the hummingbird is deciding which flower to drink from,
but you could argue that the plant - by controlling nectar production -
is dictating the movements of the hummingbird.
Many hummingbirds have a bill which, in its length and curvature,
matches the shape of the particular flower on which they mostly feed.
The violet sabre-wing's beak fits into the columnea flower
as accurately as a dagger slipping into a scabbard.
And the flower has stamens placed in precisely the position needed
to put a dab of pollen on the bird's forehead.
So the sabre-wing and columnea have become partners.
This suits columnea because its pollen is not taken
by birds feeding on other kinds of flowers, and so wasted.
And it suits the sabre-wing
because, since no other bird has this shape of bill,
it has all the columnea nectar to itself.
But not quite.
The mountain gem hummer has other ideas.
It's waiting for the flower's partner to leave.
Its bill is too short to reach the nectar as the sabre-wing does.
With a thrust from its wings, it tries to pierce the flower.
This time, it holds the flower with its feet.
It's broken in. Columnea has been burgled.
In the lush forests of the tropics, where flowers bloom all year,
animals that feed on nectar can always find a drink somewhere.
But in other parts of the world, where the winters are bitterly cold,
or here in the 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.
These mulga trees produce nectar on which ants feed,
and they have the most extraordinary larders.
The galleries of their nests lie four feet or so below the ground.
These golden globes hanging from the roof
are their storage pots full of honey.
Each one is alive -
an ant with an abdomen expanded to the size of a grape.
The small dark flecks are the hard plates
which protect the body of a normal-sized ant.
It's the membrane between them that has stretched.
These bloated individuals are almost totally inactive,
so they consume little of the honey that they hold.
It is drunk by the busy workers
who, when there's little food above ground,
come down here and induce the honeypots to regurgitate it.
The workers also tend the swollen bodies,
keeping them well-groomed and clean.
During 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
by feeding it to them drop by drop.
The people who have roamed these deserts for millennia - Aborigines -
have always valued these ants as one of their few sources of sugar,
and they eat them just as they are.
Mmmm.
It's liquid, warm, and marvellously sweet.
A few weeks after flowering,
many plants tempt animals with another food - fruit.
They have another problem.
Their seeds are formed and need to be distributed.
By wrapping them in sweet edible pulp,
they recruit lots of animals to do the job.
The trees dissuade animals from collecting the fruit before the seeds are developed
by not producing the sugars in it until the last moment.
So unripe fruit tastes bitter and is really not worth picking.
To indicate when it is, the fruit often changes colour.
Squirrel monkeys are primary fruit eaters.
They move about in large groups of 40 or so,
and must wander over a great area to find all the fruit they need.
Capuchins, on the other hand, live in small families -
each with its own patch of forest.
They eat all kinds of things,
but if there's fruit in their territory, they'll know about it.
So although the squirrel monkeys are frightened of the bigger capuchins,
they still follow them as they forage.
There may be something for the capuchin - a lizard maybe - but no fruit.
So the squirrel monkey is not interested and must wait.
The capuchin moves on.
And the squirrel monkeys follow.
As the capuchins get near the fruiting tree,
the squirrel monkeys, smelling the fruit, scamper ahead
to try to get to it before the more powerful capuchins reach it and drive them off.
Now they must grab as much as they can as quickly as they can.
The capuchins arrive.
It's time for the squirrel monkeys to go.
They take with them, inside their stomachs, the tree's seeds.
They pass through the monkeys and then, some distance away,
they're deposited with a convenient dollop of fertiliser.
Seeds themselves are packed with nourishment,
so plants enclose them in shells,
which can be strong enough to defeat even a mangabey.
Victory to the plant.
But the chimp is so clever, it can crack them.
Victory to the animal.
Sharp teeth enable an agouti to chisel into the acorn of a tropical oak.
In spite of the acorn's armour,
it seems that the oak has lost this contest.
But not totally.
The oak produces more acorns than the agouti can eat immediately.
Those that it can't, it carries away and buries for later.
But an agouti's memory is not infallible.
Occasionally, it will forget about an acorn,
which may germinate and grow into a new oak.
That will be a victory for the plant.
Perhaps the most extraordinary of all tools for nut eating
is wielded by a strange Madagascan lemur, the aye-aye.
First it gnaws a hole, then scoops out the contents with this long bony probe,
which is, in fact, its finger, but one quite unlike its others.
This curious digit serves just as well for eating a grub.
The aye-aye uses it to mash up the body in its burrow,
and then flicks out the puree.
The macaw has, almost certainly, the most powerful nutcracker of all.
It can demolish even the most resistant of nuts.
Many of the seeds macaws eat are also filled with poison,
yet this doesn't seem to upset them.
How do they survive?
Every day, they make long journeys through the forest
to dose themselves with a special antidote.
Macaws usually fly in pairs.
Only in such places as this do they assemble in flocks.
They've come to collect their medicine.
The regular presence of so many birds attracts eagles and other predators,
so before the macaws come out of the trees,
they want to be sure that it's safe to do so.
They wait for one bird, braver than the rest, to make the first move.
There it goes. And this is what they're after.
Kaolin.
The soil in this river bank is rich in it.
Several kinds of parrots and macaws come here every day from miles around
to take the treatment.
Kaolin combats acidity in the stomach,
absorbs and neutralises poisons.
As a bonus, this clay is rich in calcium and sodium,
which is lacking in diets that consist of fruit and nuts.
So eating plants poses more problems than one might think.
Eating other animals has more obvious difficulties.
For a start, you have to catch them.
Barracuda - among the most ferocious hunters in the sea.
They regularly drive shoals of small fish into the bay.
The gulls - those great opportunists of the bird world -
are ready to take advantage of the barracuda's hunt.
The pelicans can tackle the shoals
even when they're a foot or two beneath the surface.
But a pelican can only swallow the fish it's scooped up in its bill
if it lets the water drain out first.
To do that, it must open its beak slightly,
and that is the moment the gulls are waiting for.
Among all the many and varied ways of collecting food,
there can surely be none more elegant and ingenious
than the webs of orb spiders.
One of the biggest of these webs, which may be two yards across,
is constructed by the nephila spider.
She is huge.
Her legs can span six inches and she's virtually blind.
A fly blundering into her web is quickly seized.
She rapidly injects it with a venom
that will liquefy the contents of its body.
She then wraps it up in silk
and parks it on the web to allow the venom to take effect.
But nephila is not alone on her web.
Argyrodes is tiny, much smaller even than the fly.
She could easily become a meal for nephila.
She too is blind, but she's also felt the vibrations of the fly.
With what seems like suicidal recklessness,
she approaches nephila, still feasting on her prey.
And she too begins to eat food that nephila not only caught,
but has conveniently pre-digested.
Another capture calls nephila away.
Once again, she stabs the fly, trusses it up
and carries it away to hang on the side of the web.
She'll eat that later.
Argyrodes seems well aware of what's going on.
As soon as nephila has hung up her latest catch,
argyrodes starts trying to discover its position
by pulling the web filaments.
Nephila has returned to finish her first meal.
Meanwhile, argyrodes has run a line from the top of the web to the fly,
which she's now cutting loose.
Once the fly is free of the web, she lowers it down.
The stolen fly is now hanging entirely free.
Nephila won't be able to reclaim it now,
but argyrodes must get it to a place where she can feed on it in safety.
Step by step, she heaves it up.
Her theft is complete.
Other hunters are robbed of the food that might be considered their due
not by stealth, but by straightforward force.
Tropic birds nest on this cliff in Tobago in the West Indies.
They're magnificent fliers,
able to exploit all the currents of the air with spectacular ease.
They fish out at sea,
and every day the hard-working parents return to their nests
with crops full of food for the family.
But pirates are lying in wait.
Frigates, in the 18th century, were swift, heavily-armed warships
which plundered merchantmen.
These are frigate birds.
The fishing fleet is returning.
The frigate wasn't trying to kill the tropic bird,
only to make it surrender its cargo of fish.
But it'll have to find a less determined victim.
The usual tactic is to come up astern of the chosen victim
and grab its leg or tail.
It surrenders.
There goes the disgorged fish, and the frigate catches it.
The frigates aren't always successful.
Watching them, you can't help wondering
if it wouldn't be easier to catch the fish themselves,
and, indeed, they often do,
but they seem positively to enjoy a life of piracy.
As to the tropic birds, most of them escape,
and those that are caught only lose a few fish.
But it's only a short step between robbing your victim and killing him,
for the pirate to become a hunter.
And that raises a completely new set of problems.
It's those that we'll be looking at in the next programme.