FIRST IMPRESSIONS : A GREEN WALL

Standing at the edge of the forest, the first impression is that of an IMPENETRABLE GREEN WALL. It seems to be a jumble of uniform vegetation. This uniformity is only apparent, it really hides a tremendous diversity.
There are all sorts of tropical forests : forests of the plains, of the mountains, flooded forests, etc..
At first sight, nothing looks more like the Amazonian forest than the forests of Gabon or Borneo.
However, they have nearly no plant or animal species in common! Their apparent similarity is due to a convergence phenomenon brought about by similar climatic conditions.
To simplify, I will use the term rainforest.
In general, during your hikes, you will notice that it has two states:

THE PRIMARY RAINFOREST: it is what the Guyanese call "grand bois" (bid wood). It is an ancient forest, which has attained its equilibrium point.
The canopy formed by the corolla of the big trees is so dense that only dim sunlight reaches the ground.The underwood is sparse,uncluttered and covered with dry leaves.

THE SECONDARY RAINFOREST OR "JUNGLE": It is the result of a perturbation of the primary rainforest by a natural phenomenon or one brought about by humans leading to the partial or total elimination of the large trees. The ground receiving abundant light, an inextricable entanglement of small shrubs, palms, and creepers is formed, rendering progression difficult and slow, with the inevitable use of the machete. A specie of disagreeable sharp-edged grass often grows there.
It is the forest that you most often see in movies. I suppose that, for budget reason, they are filmed near inhabited zones where the rainforest has deteriorated.
Secondary rainforests are dominated by fast-growing species, like the typical various species of "cecropia" (called "bois canon" in Guyana) which may grow more than 5m per year.

Their life span is short, twenty or thirty years in general, and they are replaced little by little by slower growing dominant species.
The secondary rainforests are "transitory", they tend to return to the primary rainforest state. They represent the regeneration process of the primary rainforest : a large tree falls, the gap in the forest allows light-loving species to develop… The exact duration of this regeneration is unknown, but it certainly involves several hundred years !
The rainforest has sometimes been represented as a large garden of Eden where man just has to reach down to pick all the fruits of Creation. Nothing is falser. The tropical forest is not a garden, and even less a vegetable one !

Tropical forests are rather dark, especially primary ones. Most plants tend to reach up for light and thus flower very high (most trees have a straight trunk and open out only near the canopy). The flowers of many creeper species will be found above you.
Flying over the flowering canopy at the end of the dry season is simply marvellous. In the secondary zones, there are of course more flowers, easily seen and generally red or orangey (heliconia "bird of paradise", passiflora "passion flower"), but don't expect to see spring blooming like in Europe.

As for the thousands of orchid species, they are usually perched high and are small. Some bloom during the rainy season, others during the dry. Some, like the spectacular "cattleya" are abundant on the river banks.

As for fruits, don't expect to gather them for your eventual "survival". There are of course many fruit trees, but you will have to overcome the hard competition of the local voracious and efficient fauna : monkeys, parrots and other toucans all actively feed on fruit. The ones fallen on the ground will not remain intact for long : "agoutis", "pacas" and wild pigs will deal with them rapidly.

Mango and banana trees originate from South East Asia and were imported by the Spanish and Portuguese. Don't hope to find them in the rainforest, you will only see them on plantations.
SECOND IMPRESSION : WHERE ARE THE ANIMALS ?

THE RAINFOREST IS SILENT AND SEEMS….EMPTY

There again it is only an appearance. Animals are there. They see you, they listen to you, and they smell you… It will take a lot of effort, patience and chance to see them yourself. Walking through the great rainforest is plunging in a mysterious and complex ecosystem.

IT IS NOT A SAFARI !

Vegetation is so dense that, even in the primary rainforest, you will rarely see beyond some thirty meters, if that. In the secondary rainforest, barely a few meters..
You will not be able to post yourself and observe large animals one kilometre away through spyglasses, like in the African savannahs !
The Amazonian zone mammals are generally small, discreet and expert in the art of camouflaging.

BIODIVERSITY AND INTERACTION

In order to tackle the equatorial forest adequately, it is fundamental to underline the importance of two essential phenomena that characterize it : the biodiversity and the extremely complex interaction between animals and plants.
Here are some enlightening examples of BIODIVERSITY :

In temperate zones, there are at most around thirty-three species per hectare. In certain regions of Amazonia, more than three hundred species have been itemized in the same amount of space !
 In two months, an ornithologist has counted more than 600 bird species from a small scientific station in the Manu national park in Peru, this represents about the same number than in the whole of North America !
 More than 40 kinds of ants have been counted on a single tree of Peruvian Amazonia, about as much as in all the British Isles.
 In small Costa Rica alone, there are more than 120 kinds of frogs !

INTERACTION AND INTERDEPENDENCE

Species are both dependent and compete with each other, which leads to a fragile equilibrium. The incredible biodiversity of the rainforest renders the equilibrium extremely complex.
The basic idea is that each specie, however modest, has its importance in the general equilibrium and represents just one link in an immense chain…
Example : pollinization
Most flowering plants of these regions totally depend on insects, birds and bats for their survival : the rainforest's density renders wind pollinization inefficient, except perhaps for the very large dominant trees.

Another example : that of the atta type leaf-cutting ants (more than 200 species). They live in colonies of up to 5 million individuals. They cut the leaves of certain trees (not all…) and bring them under the earth. They "cultivate" on these leaves a mushroom on which they feed. This mushroom does not exist elsewhere in nature. It can digest the leaf cellulose, something the ants are incapable of doing. The ant cannot exist without this mushroom, which does not exist without ants…
(A large tree, "hymenaea courbaril", has developed an original protection to prevent the atta ant from denuding if of its leaves : it contains elements which are toxic not for the ant but for the mushroom !). The ecological impact of the attas is considerable. They manage to form true 20 cm large "highways" on the ground. Studies have shown that they consume by themselves as much foliage as all the herbivorous vertebrates of the rainforest.

Last example even more fascinating : Another specie of ants, pseudomyrmex ferruginea, lives on certain acacias. They systematically attack any "visitor" (insect or human hand). But they also cut with their mandibles plants that start to grow on or above the tree and which might hinder its growth. As a counter part, the acacia has developed cavities to shelter ants and also secretes a nectar to feed them !

DEFENCE MECHANISMS AND MIMICRY PHENOMENA

Nearly every specie has its predator and each one has developed means of defense against them.
Before fight or violent confrontation, one of the principal means of defense is to become undetectable. That is why you have the impression that the forest is empty.
The mimicry phenomena are fascinating :

. Certain species disguise themselves to escape from predators (defense mimicry).
. Others try to become undetectable by their eventual prey (offensive mimicry).
. Often both kinds of mimicry are found in the same specie…

A perfect example of defense mimicry is found in the phasms, these insects look exactly like twigs.

Mimicry is never absolute, it is always relative to the surrounding environment of the animal or to certain of its elements. The coat of jaguar for example: its black-spotted yellow looks garish against the cement of the Zoo on which the animal rests. But believe me, in the forest, the camouflage is very efficient. Most territorial animals of the rainforest are nearly undetectable IF THEY ARE NOT MOVING.

How have they become so adapted to their surrounding environment?

This is what the THEORY OF THE EVOLUTION OF THE SPECIES, developed in the second half of the 19th Century by Charles Darwin and Alfred Russel Wallace, tries to explain. Both stayed for a long time in the Amazon zone and found there many sources of inspiration.

Schematically, within a specie, certain individuals have certain characteristics that make them more apt to survive than others in a similar environment: for example, the darker an animal is, the less detectable will it be against a dark background.
From then on, the darker individuals have an advantage … being less susceptible of being seen by predators, their number will tend to increase proportionately and the "dark" gene will become progressively dominant.

This evolution occurs sometimes "relatively" fast. One of the best known cases is that of a butterfly. Following the 19th Century industrial revolution and the smoke it generated, some specimen of this specie, originally light grey, have become nearly black!

In Amazonia, this adaptation can be totally fascinating:

For example, an extraordinary case of offensive mimicry: certain small spiders feed exclusively on ants.
Their body has evolved to strikingly resemble the body of one of these insects:
The cephalothorax (the characteristic thorax/head unit of arachnidae) has divided itself in order to make believe there is a head.
The first pair of legs has lost its ambulatory function to simulate a pair of antenna.
Thus these spiders can become undetectable by ants.


Other cases, this time of defensive mimicry, concern many harmless animals imitating aggressive or poisonous species.
Certain butterflies resemble wasps so much that you cannot tell them apart.

Certain grass snakes imitate perfectly the spectacular skin of a very poisonous coral snake specie.

These examples are relatively simple. The mimicry phenomena can be much more complex in their relation to the surrounding environment.
A study on the butterflies of Peru has shown that a specific colour of wings corresponds to different strata of the great rainforest:
From ground level up to 2m high : the "transparent" zone : transparent wings with black streaks.
From 2 to 7m high : the "tiger" zone : wings streaked with yellow, brown, black and red.
From 7 to 13m high: the "red" zone: red is the dominant wing colour.
From 15 to 30m high: the "blue" zone.
From 30m to the canopy: the "orange" zone.

These are the dominant tendencies, of course, and it does not mean that no blue butterflies will be found near the ground! But the hypothesis being defended is that each "complex" or "colour" corresponds to the best camouflage of the butterfly when it flies, according to light conditions in the different forest strata.

More rarely, instead of mimicry, certain species "choose" to deliberately attract attention by loud colours, generally based on yellow, orange and red, to warn the predator of the danger they represent in case of attack. These are generally poisonous or venomous species. In this case, it calls upon the genetic memory of the aggressor.

Two splendid examples:

-The coral snakes (micrurus sp)

-The dendrobate frogs (their skin secrete an extremely active venom).

Unfortunately for the amateur photographer, coral snakes and dendrobates are shy creatures, they hide most of the time in the humid ground cover of the forest or under dead wood.

Finally, certain batrachians, reptiles or insects show "flash" colours, with the aim of "blinding" or momentarily impressing an aggressor thus giving them time to flee. "Agalychinis Callydrias", a small tree-climbing frog of Central America has for example large brilliant red eyes. It stays usually on leaves with closed eyes. When it opens them, the effect is surprising!!

As a conclusion on mimicry, there are mysteries!

Take for example the case of the large macaw, linked to the parrots:
They are large and highly coloured.
They belong to the rare loud animals of the great rainforest. I will even say VERY loud!
These animals make no effort to hide, I therefore thought that they had no predator. How wrong! I once saw a great harpy eagle "murder" one of these birds.


All this is fascinating, you will tell me, but a little discouraging. Is there no chance of seeing wild animals in the rainforest?
There is, of course but YOU HAVE TO PUT ALL LUCK ON YOUR SIDE BY LEARNING TO BEHAVE ADEQUATELY IN THE SURROUNDING ENVIRONMENT.
You know now that a walk through the forest is no safari. Any passive attitude will be sanctioned by failure. You have to stay concentrated, make great efforts of attention…
First of all, there are AUSPICIOUS HOURS, and those that are not. At the height of the heat, animals limit their moving about. Prefer the morning or the end of afternoon.
Birdwatchers know it, it is necessary to get up early.

Learn to use all your senses, in particular hearing and smelling. As has been shown, it is rare to localize an animal by sight.

LISTENING IS FUNDAMENTAL :

First of all, some species, very hard to see at first sight, can be localized by their cry. I have spoken of the macaws, in fact, the discordant cries of all parrots can be heard from rather far.
The shrill whistling of the large toucans is easily recognizable.
 

A small bird, the screaming piha (lipaugus vociferans) has what might be called a very characteristic song (!) that you will hear very often…the males spend three quarter of their time calling the females.

One of the most characteristic sounds of the great rainforest is the cry of the howler monkey (alouatta sp) : it is somewhat similar to the sound of the wind during a raging storm.
These howls can be heard kilometres away and are very impressive when close by.
They are due to a sort of goitre that these monkeys have and which serves as resonance chamber.

 

Among insects, the sound of innumerable cicadae can be deafening…
At night, the batrachians take their turn, certain species can prevent you from sleeping : one day, I camped under a large tree in the south of Venezuela. Shortly after sundown, a true concert of tree-climbing frogs started above our heads.
The Ye'Kwana Indian chief who accompanied me got up from his hammock, requisitioned a young Indian and showed him the tree. The next morning, the boy proudly showed us the culprits : he had not killed them but had captured them and had carefully tied them together with fine lianas. The chief ordered him to liberate them… This small anecdote gives you an idea of the psychology of the Indians, a subject that I will treat later.

All these are sounds that hardly go unnoticed.
In most cases, you will have to listen carefully to hear the slightest sound…
The slightest rustle of dead leaves can mean a reptile on the ground, a creak above you, a monkey in a tree.

The other senses

THE USE OF SMELLING IS ALSO FUNDAMENTAL

Some species smell strongly, either directly like the wild pigs, or indirectly through their urine, like the howler monkeys and the felines that mark their territory like this.

The only time I encountered a giant armadillo (priondontes maximus), a rare nocturnal specie that can attain 60kg, I mostly heard him dragging himself along dry leaves and I smelt him! The animal really stank!

SIGHT

No need to open your eyes wide to look at what passes as a horizon, your chance of directly seeing an animal is just about nil, but try to notice traces. When I speak of traces, I don't mean only tracks on the ground, but also the secondary manifestations of animal presence :
The foliage which moves a few meters ahead of you.
Branches that move in a tree in front. That is why it is simpler to see monkeys if there is no wind…

Similarly, if you pass through a place littered with fruit, look carefully in the trees and around you, there is a strong chance that a fruit-eating animal, mammal or bird, is hiding nearby.

As a corollary, during hikes :

Don't speak continuously to your guide. It is he who, most of the time, will spot the animals that you will see. If he has to turn around every 30 seconds or so, he will not be able to do his work correctly. Needless to say that if you spot, hear or smell something interesting, you must share it with your group, but keep questions of general interest for later, if need be, write them in as small notebook.

Walks in the forest are usually done on narrow trails, single file. Your guide must be at the head, for it is he who is most apt to spot a snake coiled up on the trail.

Don't stay too close so as not to hamper him, especially if he has to use his machete often, but don't stay too far either. Seeing an animal is generally furtive, a few seconds or less (I am not speaking of invertebrates).

If you are too far, you will be told "I just saw an agouti, but he escaped quickly" or "you just missed a group of spider monkeys" and other frustrating remarks because you will not have seen anything.

If there are many of you, organize rotations in order not to have always the same one be behind the guide.

Be patient, don't get discouraged, try to remain in a state of concentration, even if the walk is long. I remember guiding a hike that lasted three days during which we saw nothing. The last evening, I offered a night walk. During two hours, we saw nothing. Coming back to the place where we had left our dug-out canoe, I found myself face to face with a superb puma, not intimidated at all. I made desperate signs towards the rear to try to attract the attention of my companions but they were at least 50m away, in the process, I presume, of telling each other about their last beach week-end. When they arrived at last, the animal had of course disappeared!

My personal experience has shown me that, in a group, it is always the same ones who see something, and always the same ones who see nothing!
Remember however that even with the best intentions in the world, the chance factor is important and the fact of having purchased an organized tour does not give you a guarantee of meeting animals.
The rainforest is mostly an atmosphere. It is in the Zoo that you will see the animals best from close!