Forests have flourished in the tropics for longer than they have existed anywhere else on earth, which helps to explain why the animal species that live there outnumber those of all other land habitats combined.
Most large tropical forest animals have been identified and classified, but the invertebrate life is so diverse that the task of cataloging it will never be complete.
There are 2 main types of tropical forests: rain-forest, which is closest to the equator; and seasonal, or monsoon, forest, which grows towards the edges of the tropical belt.
Near the equator, the climate is warm and moist all year round, creating ideal conditions for plant growth as a result, trees and other forest plants grow almost incessantly in an endless competition for light. Some plants put all their resources into growing towering trunks, while others are adapted for survival in partial shade.
As a result of these different growth patterns, the forest is divided into clearly defined layers, each with its own characteristic animal species. The highest layer, at about 75 m (245 ft), consists of giant, isolated trees called emergents. These provide nest sites for predatory birds and feeding platforms for monkeys. Beneath this level is the canopy, where copious light, combined with some protection provided by the emergents, results in a continuous layer of branches and lush foliage up to 20 m (65 ft) deep. This layer feeds or harbors most of the forests animal life. Below the canopy is the understorey — a more open layer made up of shade-tolerant trees.
On the forest floor, leaf litter is food for some very small animals as well as support for plants and saplings that grow where sufficient light filters through from above. This zonal pattern is characteristic of lowland rain-forest (the most common rain-forest type), At higher altitudes, the trees are lower and the layers are more compressed — an effect that is exacerbated as altitude increases until eventually the trees form elfin forests little more than head high.
Soil is also an important factor in shaping the forest. In some parts of the tropics, such as the Rio Negro region of South America, infertile sand results in the growth of stunted trees with leathery leaves.
SEMI (MONSOON) FOREST
Unlike rainforest, where the clirnate is very stable, seasonal forest grows where rainfall is concentrated into a wet, or rainy. season, which is known as a monsoon. Up to 2.5m (8 1/4 ft) of rain can fall in just 3 months — as rnuch as some tropical rainforests receive throughout the whole year.
As a consequence. seasonal forest is not as tall as tropical raintorest and. typically, the canopy is more open and extends further towards the forest floor. lmrnedlately after the monsoon, seasonal forest is lush and green; but in the long dry season that follows rnany of the trees shed the leaves, and the percing sunlight is able to reach through the bare branches to the ground.
Some seasonal forest trees are unusual in that they flower and fruit after losing their leaves. Where this happens, birds, insects, and mammals congregate in large numbers to feed, in the rainy season. the forests animals are well hidden by the foliage: once the leayes have fallen, they become much easier to tind.
Despite the yearly oycle of deluge and drought. the animal life of seasonal forest is some of the most numerous and varied in the world. In southern Asia. which has the largest area of this type of forest. the habitat supports elephahts. monkeys. leopards. and also tigers. In Asia’s seasonal forests. there are some spectaouiar birds. including giant hornbills. ahd some of the worlds largest snakes. is Atrioa. seasohai torests abourid with browsing ahteiopes whiie.
In Cehtral America. they are inhabited by pumas. coatis. and white-tailed deer deer. Most of these animals breed during the wet season. when they can take advantage ot the abundant supply of fresh leaves.
LIFE IN TROPICAL FOREST
Some tropical forest animals spend all their time on the ground. For most, however, daily life involves getting about among trees. The canopy holds most of the forest’s food, so an animal that is good at moving around in the treetops has the greatest chance of thriving.
Some animals are so well adapted to life in the trees — breeding as well as feeding there — that they very rarely have to visit the forest floor.
MOVING IN TREES
Small animals need relatively few special adaptations for moving about in trees. Ants, for example are so light that it makes little difference to them whether they are travelling up and clown trees or across the forest floor.
But for larger animals, such as apes, monkeys, and other primates, climbing is a dangerous occupation: if they lose their grip — as occasionally happens — they risk a fatal fall. Most primates climb by running or leaping along the taps of branches. Often using familiar routes that act like highways through the trees. Monkeys follow these routes mainly by sight, but many of the more primitive primates, such as bush babies move about after dark, identifying their pathways partly by smell Gibbons are different they travel underneath the branches by swinging hand-over-hand in a breathtakingly acrobatic manner.
This unusual but highly effective form of movement is called brachiation. Tropical forest harbors a huge variety of flying animals — birds, bats, and flying insects — that swoop or hover among the treetops. However, during the course of evolution, many, unrelated animals including mammals, frogs, and even snakes, have developed wing-like flaps of skin that enable them to glide. Some of these gliders can travel over 100 m (330 ft) from tree to tree and remarkably, many of them are most active after dark.
In any kind of forest, animals face problems keeping in touch. In the canopy, leaves and branches make it difficult to see more than a few meters, while tree trunks get in the way on the ground.
As a result, many forest animals rely on sound and scent, rather than visual signals, to claim territories and attract partners. Some of the loudest animals in the world live in tropical forest. They include howler monkeys, bell birds, parrots, cicadas, and an enormous variety of tree frogs. Like mammals and birds, each species of tree-frog has its own characteristic call: some produce a short metallic “tink”; others generate a sustained trilling that sounds like machinery.
Signalling with sound can be dangerous because it can attract predators as well as potential mates. Tree-frogs and cicadas minimize the problem by pitching their calls so that the source is very difficult to locate.
Other animals, including many mammals and flying insects, avoid the problem by using scent to stay in touch. One great advantage of scent is that it lingers: for example, in marking its territory, a jaguar or okapi leaves a signal that will last for several days.
KEEPING OUT OF DANGER
Tropical forest abounds with camouflaged animals as well as species that mimic others, animals that use camouflage — chiefly insects and spiders, but also snakes, lizards, frogs, and toads — resemble a huge variety of inanimate objects, from bark, thorns, and bird droppings to branches and fallen leaves.
Many animals use camouflage to avoid being spotted and eaten, but some predators also use it to enable them to ambush their prey. Mimicry, in which one species “pretends” to be another, is a subtler means of avoiding attack. It involves a relatively harmless species evolving to look like one that is dangerous, and it is most common in invertebrates. Some tropical forest spiders, for example, closely resemble stinging ants and even move like them.
Matters are complicated where several species come to look alike. Some groups of unrelated butterflies, which contain poisons that are distasteful to birds, imitate each other: thus they have evolved the insect equivalent of a shared warning trademark. Warning signals are most developed in extremely toxic animals. For example, unlike other frogs, tiny poison-dart frogs hop nonchalantly about the forest floor, relying on their extraordinarily vivid colors to warn other animals that they are not merely unpalatable but highly dangerous to eat.
Near the equator trees grow, flower, and set seed all year round. generating a nonstop supply of food.Many forest animals — Including bats, bird’s and insects – live almost exclusively on the abundant nectar and fruit. Some of these animals help trees to spread their pollen and seeds.
Quetzals for example, swallow fruit whole, and then regurgitate the stones onto the forest floor where they, can germinate. Compared with flowers and fruits tropical forest leaves are difficult to digest.
Animals that feed on these leaves generally pick them while they are still young — before protective toxins have had a chance to build up inside them. Insects are the most prolific leaf-eaters, but some of the forests larger animals also rely on this difficult diet. They include several Kinds of monkeys and sloths, and the hoatzin — a highly unusual bird from South America.
The hoatzin processes its food much as a grazing mammal does: after eating it is often so heavy that it can barely fly. Tropical forest predators range from some of the worlds smallest insects to the largest cats. In an environment that provides lots of cover, most of them stalk their prey rather than running it down. Army and driver ants are the most remarkable exceptions: they hunt in “packs” over 50,000 strong overpowering and eating anything that cannot escape.
For animals that live in trees, breeding can sometimes involve unusual adaptations. Some tree frogs come down to the forest floor to lay their eggs, but many lay them high up in the canopy, either in water- filled tree holes or in the pools of water that gather in plants. Some frog species are more creative lying their eggs in nests of foam that keeps their eggs moist until the tadpoles are ready to hatch.
Many tropical birds start life in the safety of tree holes, but climbing mammals rarely build nests, and many of their young start life in the open. Young monkeys often cling to their mother’s chests, keeping a tight grip the parent run along branches and or leaps-through the air.
For young murine (mouse-like) opossums, which live in the American tropics, early life is even more precarious because their mothers do not have developed the ability to cling, these tiny marsupials hang from their mother’s teats by their mouths , their legs dangling in the air.