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Hi, I'm George Page for Nature. Tropical forests are like magnets to biologists and
wildlife filmmakers. It's not surprising when you consider that they're home to almost half
of the earth's plant and animal species, and make up one of our planet's most basic life
support systems. For close to a hundred million years, tropical forests have encircled the earth,
incubators, where the great diversity of land life evolved. Life in the tropics has to meet
very different challenges from those in temperate climates, where the major problem is dealing with
the cold of winter. In the tropics, there is no winter, and so the animals and plants have
evolved in response to each other. And because so many life forms flourish, the challenge is to
coexist, to get along. As a result, many bizarre associations have developed. This week's film
was made in the Central American countries of Belize, Costa Rica, and Panama. The rainforest
there is called Selva Verde, the green jungle. At night, in a Central American rainforest,
a killer prepares.
The prey is a young bat.
Predator and prey are bound together by ties stronger than silk. Each is a part of a larger
organism, the forest, which like all other ecosystems, benefits from death to sustain life.
The young and the old are at risk, but there is coexistence between species, as well as
vicious struggle. For healthy adults, the forest is a relatively safe place. Their special skills
enable them to find food and not be eaten. The margay, with its almost unbelievable climbing
skills, is without equal as a predator of the treetops.
More plants and animals are found in tropical forests than anywhere else on earth. But competition
for food is intense, and often animals are both hunter and hunted. The dead leaf mattis
has to be well disguised while hunting a grasshopper, so she doesn't end up as a meal for someone
else. Only in the few minutes at dawn before their predators start foraging is it safe
to mate. Even mating has its dangers for the male mantis. He must avoid being eaten not
just by other predators, but by her. She is stimulated by the dawn light to release a
sexual odor which draws him to her. He approaches cautiously, not knowing that she's already
eaten. As it gets lighter, the mantis resumes its
daytime disguise. Other mantises look like living leaves. This leaf is actually a katydid
grasshopper. Other katydids resemble dead leaves, but some have taken camouflage to
strange extremes. The sudden movements of this insect destroy the illusion that it's
a stick. A treehopper appears to mimic a thorn, but it's probably just making itself difficult
to eat. Instead of hiding, some animals, like the poison arrow frog, use brilliant colors
to advertise their poisonous nature. And others seem to court danger, like this fly which
spends its adult life on the back of a golden orb spider so it can rob its feeding host.
With the change of light, the leaves change. They begin to capture the energy of the sun
and convert it into chemical energy. It's the lifeblood of the whole forest, and a chain
of predators and prey circulates this energy through the forest community. These caterpillars
protected by their stinging hairs are at the beginning of the chain.
This extraordinary structure is a bivouac of living ants, a temporary home for these
forest nomads, which make up part of the second link in the chain. As the forest wakes, the
bivouac dissolves into a column of army ants. For other insects, a raiding swarm is one
of the deadliest predators on the forest floor. Many live as scattered refugees from the raiding
column, often safe for generations until the ants come back.
Locally, these small predators have a much more devastating effect on their prey than
larger ones. Often, animals like the peccary live alongside and within sight of their predators.
The jaguar is unable to pursue a life of indiscriminate slaughter like the army ant. She goes about
killing cautiously. If she injures herself while hunting, it could be fatal, so she'll
take the easiest prey available. Stranded catfish are ideal.
There's no winter here and plenty of rain and sunshine, so the plants and animals have
evolved more in response to each other than to a harsh environment. The impact of predators
and the need to compete for food and shelter have forced all of the inhabitants of the
forest to become increasingly specialized in the ways they interact. The survival of
the forest depends upon these interactions. To understand them is to understand the forest
itself. All plants live under persistent attack by
animals and most plants respond by defending themselves, but every new defense provokes
a more sophisticated attack. This plant, Marchia, is able to move poisons to any of its threatened
leaves. However, the Melania caterpillar has responded and in a quite extraordinary way.
It foils the plant's defenses by nibbling a circular canal before the poisons can reach
it. It's then able to feed on the center of the leaf, safe from the plant's defenses.
Later, when the caterpillar is bigger and stronger and needs more to eat, it severs
the main vein of the leaf, again to foil the plant. It appears to store the poisons that
do get through in a special sack near its gut. They will help to protect it in its later
life as a butterfly. To prepare for this life, the caterpillar searches for a safe place
to pupate. There's a critical moment when the pupa must attach a special hook to the
leaf. This anchors it securely during the miraculous change.
. She expands and dries her wings. Most butterflies only live for a few weeks.
Melania is different. She must survive for many months to be sure of finding enough
marquia plants on which to lay her eggs. She solves this problem by seeking out the
raiding army ants. This is a dangerous place for insects. Those able to escape the ants
are often caught by birds which follow the colony. The pickings are so rich that some
species like the spotted ant bird are almost never found away from the colony. The bicolored
ant bird also depends on the colony, and like the spotted ant bird, it doesn't feed on the
ants, only on their fleeing prey. The birds will certainly attack a passing
butterfly, but Melania signals with her brilliant color that she's poisonous, protected by
the plant on which she fed as a caterpillar. She has to seek out the ants because it's
only with them that she can be sure of finding the birds and their droppings. These
droppings contain the vital chemicals, amino acids, which will make her live longer and
therefore lay more eggs. Not all predators are warned off by Melania's colors. Much
larger than an army ant, the paraponera is a solitary hunter and keeps his prey to himself.
Other butterflies not protected by poisons like Melania are colored like her to discourage
predatory birds. Male Melania butterflies need plants too, but dead ones. They seek
out plants of the Heliotropium family. When these plants die, they produce special chemicals,
alkaloids. The butterfly takes them in through his proboscis and with them makes pheromones
or perfumes, which it then gives out through its special hairs to attract females. These
alkaloids are poisonous and may also protect the male throughout the rest of his life.
However, during mating, it's even possible that the male passes these alkaloids onto the
female, along with the sperm, which fertilizes her eggs. The alkaloids may help protect her
later during the dangerous and lonely task of seeking out the marquia plant to lay her
eggs and perpetuate her species. The whole web of forest relationships is held in a balanced
tension by the need to eat, to reproduce, and to avoid being eaten in the process. The
three-toed sloth has evolved a quite different technique for overcoming plants defenses and
for protecting itself, slowness. It uses energy at about half the rate of other animals its
size. Its body heat, for example, is regulated by the temperatures of the air, and its digestion
is so slow and complex that it's able to feed on many kinds of leaves which other animals
won't touch. No two sloths will feed on exactly the same range of tree species. This greatly
reduces the competition between them and enables more sloths to live in a forest. Moving slowly
has another advantage. It allows the sloth's hair to stay permanently damp, and together
with the forest's high humidity, this provides ideal conditions for green algae to grow.
As a result, its greenish, unkempt appearance actually enhances its camouflage. And this
offers an ideal environment for a species of moth which lives in the hair, probably
feeding on the algae.
Every few days, the sloth climbs down to the base of the tree to defecate. This is
a vital moment for the moths. They lay their eggs on the droppings, and it's here that
their larvae will feed and develop. As the sloth moves off, they flutter back onto their
mobile home.
Curiously, one of the slowest moving mammals in the world is one of the most successful
in the rainforests of Central America, and it owes this to its bizarre lifestyle.
Food-eating birds like the toucans and these aura pendulas have played a key role in the
evolution of rainforest trees. For these birds, life appears easy. In order to get their vital
seeds safely dispersed, many tropical trees produce abundant and brightly colored fruits,
containing seeds which are indigestible. Later, the birds will excrete these seeds far from
the trees. With so much food so easily available, these birds need to spend much less time foraging.
This has allowed them more time to evolve elaborate nesting and courtship behavior.
Food-headed aura pendulas put their beaks to good use when nest building. The nest is
cleverly made by first fashioning a strong and well-attached necklace of palm leaf fiber
from which the tube of the nest will be hung later. Nesting materials are stripped from
nearby palm fronds. Adult aura pendulas live a long time, but like any animal in the tropics,
it's the first few weeks of life that are dangerous, and so solid construction and careful
Nests are usually completed in about two weeks. By nesting socially, aura pendulas are usually
able to spot and drive off predators. This is the kaku in the colony, a female cowbird.
She's monitoring the comings and goings of aura pendulas because she's going to lay her
egg in the aura pendulas nest. Her attempts to enter the nest are vigorously rebuffed.
The cowbirds are persistent, waiting patiently for the right moment. She must lay her egg
only when there's a single aura pendula egg. The elaborate deception doesn't always fool
the aura pendula. The biggest threat to the aura pendula colony is the botfly. Inside
a hanging nest, young aura pendula chicks have just hatched. They look healthy, but in fact,
the botfly has just parasitized them. The growing botfly maggot will feed on the chicks
until they die. Without some protection, the whole aura pendula colony could lose all its
chicks. The cowbirds are becoming increasingly bold and are met with less and less resistance.
Even though the aura pendulas appear to be more tolerant, the female cowbird must still
choose the right moment to lay her egg. This time, the egg is accepted and the reason soon
becomes clear. The young cowbird on the left has hatched first and although blind, reacts
instinctively to the presence of the botflies, trying to catch them, and in so doing inadvertently
protects the young aura pendula chick. So the cowbird is a blessing in disguise. This male
yellow-rumped cassete is inspecting one of the nests. He's of the same family as the
aura pendulas and often visits their colony to display. His own colony is in a tree nearby.
As the dominant male, he defends his perch vigorously against other males. The slightly
smaller females do all the nest building.
Nesting cassetes suffer the same problems as aura pendulas, but in this colony they successfully
drive off lurking cowbirds. The cassete's solution to the botfly problem is quite different.
Their colony is clustered around a bee's nest. The bees are extremely aggressive and the
sheer force of their numbers excludes adult botflies from getting anywhere near the cassete
nests. Protected by the bees, cassetes have no need to tolerate the presence of cowbirds.
Food-eating cassetes and aura pendulas have evolved complicated and mutually advantageous
relationships, even with predators. During the intense heat of the afternoon, even spider
monkeys have to rest.
The
hymenia tree has evolved a very different strategy for dispersing its seeds. It produces
such an enormous crop that it simply floods the market with seeds so that some will survive
while others are eaten.
The seed killers take many forms. Inside one of the pods is an adult weevil which has developed
on the seeds. Having eaten most of the seed, it now has to wait to be released from the
pod. Another seed killer, the agouti, specializes in large fallen pods like those of the hymenia.
Usually the agouti is solitary and territorial, but this seed crop is so large that several
agoutis are attracted to it.
The rock-hard pods containing the seeds are so difficult to break open that the weevil
can only get out with help. But agoutis also eat insects, so the weevil has to play dead
to escape attention.
Now it's safe to run off.
Having eaten his fill at the tree, this agouti has carried a seed away to his territory where
he buries it.
By burying individual seeds over a wide area, the agouti reduces the chance of their being
stolen.
Agoutis are also seed killers and are attracted to the pods. But they're not alone.
Onepiece begins at the one seed I've just tasted.
franchise short clip
This
peccary was old. It's usually the old or the young that are killed. Army ants are
not as selective as the jaguar and as a result their effect on the smaller
animals of the forest floor is much more profound. This colony is returning to the
bivouac. There are about a half million ants here and they devastate the prey
populations helping maintain the delicate balance among species.
Night brings a renewed attack on the hymenia pods.
Even a kinkajou is attracted. It usually prefers softer fruit but in its search
for a plentiful food supply it will take the pods as well even if they are hard
to open.
Liomas is a Central American mouse. It often steals the hymenia seeds.
The hymenia seeds buried by agoutis during the day.
It's a useful find and nutritious.
He's taken advantage of the agoutis ability to open the hard pods.
Occasionally, margays hunt on the forest floor, but they'll always return to the canopy to feed.
In
adapting to its specialized life in the canopy, the margay has reached perfection in design
and elegance.
Nowhere on earth, but in the rainforests, has design and color reached such dramatic
levels of expression.
But when gravity moves from the
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