Category Science

As in most other habitats, the colouring of animals in the rainforest is very varied. Some are brilliantly coloured, to attract mates or to warn predators that they are poisonous. Other creatures have green or dark colouring to camouflage them amongst the vegetation. This hides them from their enemies and enables them to creep up on their prey unseen.

Parrots, macaws, parakeets… these rain-bowed tropical birds put to shame the brown and gray birds that are so common in Illinois and Chicago. Even Chicago’s brightest birds—cardinals, blue jays, gold finches—are vibrant, but single-colored. Why are bright and multi-colored birds so common in tropical rain forests, and nowhere to be found in temperate climates like Chicago? Do the changing seasons make bright birds sitting ducks in the winter? Do jungle birds eat bright berries and fruits instead of brown and black seeds? What gives?

We can eliminate one option right away: a parrot’s color has nothing to do with its diet. While a flamingo gets its pink color from the food it eats (brine shrimp and blue-green algae) and a cardinal is red in part because of the seeds in its diet, a parrot’s color is determined by its genes. The incredible colors of the blue-and-yellow macaw do not come from tropical mangoes and imported blueberries.

It must be some other quality of the tropics that creates brighter birds: is it the rainfall? The year-round high temperatures.

The truth is that tropical birds don’t tend to be more colorful. Dr. Nicholas Friedman of the Okinawa Institute of Science and Technology explains, “If you look at birds in the tropics, there are a lot of colorful birds that stand out. But there are really more species in general there and there are just as many more of the little brown ones”.

In other words, the tropics are much more diverse in general than temperate or dry climates. The rainfall and year-round high temperatures contribute to rainforests having many more animal and plant species than other places. Of these many more animal species, some are brightly colored birds, but there are even more species that are plainly colored. The birds that are exported from the rainforests for zoos or as pets are the brightest birds, and these are the tropical birds that we in Chicago are familiar with. This leads to the overall impression that birds from the rainforest are more colorful as a rule.

The many habitats to be found in rainforests can be thought of as layers. In real forests, of course, these layers overlap each other a good deal.

Emergent Layer

These giant trees thrust above the dense canopy layer and have huge mushroom-shaped crowns. These trees enjoy the greatest amount of sunlight but also must endure high temperatures, low humidity, and strong winds.

The emergent layer consists of the tallest trees, with umbrella-like branches poking through the mass of leaves below. In this layer live free-flying birds and bats, including birds of prey.

Canopy Layer

The broad, irregular crowns of these trees form a tight, continuous canopy 60 to 90 feet above the ground. The branches are often densely covered with other plants (epiphytes) and tied together with vines (lianas). The canopy is home to 90% of the organisms found in the rain forest; many seeking the brighter light in the treetops.

The tree canopy consists of the leaves of mature trees. Their tops spread out to reach as much of the light as possible. As well as birds and fruit bats, monkeys and squirrels live in this layer, feeding on the fruits, nuts and leaves of the trees in the canopy.

Understory
Receiving only 2-15% of the sunlight that falls on the canopy, understory is a dark place. It is relatively open and contains young trees and leafy herbaceous plants that tolerate low light. Many popular house plants come from this layer. Only along rivers and roadways and in tree-fall and cut areas are sunlight sufficient to allow growth to become thick and impenetrable. 

Very little light filters through the leaves of the canopy. In the mid-zone, creepers called lianas hang in great ropes among the trees. Here there are monkeys, squirrels, birds and bats again, but also some snakes and tree frogs.

Forest Floor

The forest floor receives less than 2% of the sunlight and consequently, little grows here except plants adapted to very low light. On the floor is a thin layer of fallen leaves, seeds, fruits, and branches that very quickly decomposes. Only a thin layer of decaying organic matter is found, unlike in temperate deciduous forests.

The forest floor is very dark. Larger mammals, such as deer, tapirs, elephants, jaguars and bush pigs, forage among the fallen leaves or prey on each other or smaller animals.

Rainforests are being cut down at an alarming rate for two main reasons. Both large commercial farming companies and individual families clear the forest to gain land to cultivate and graze animals, although the rainforest soil is not suitable for this use. Secondly, forests have been felled to supply tropical hardwoods for furniture-making and building. Woods such as mahogany have been highly prized in wealthy countries for hundreds of years.

More than half of Earth’s rain forests have already been lost due to the human demand for wood and arable land. Rain forests that once grew over 14 percent of the land on Earth now cover only about 6 percent. And if current deforestation rates continue, these critical habitats could disappear from the planet completely within the next hundred years.

The reasons for plundering rain forests are mainly economic. Wealthy nations drive demand for tropical timber, and cash-strapped governments often grant logging concessions at a fraction of the land’s true value. “Homesteader” policies also encourage citizens to clear-cut forests for farms. Sustainable logging and harvesting rather than clear-cutting are among the strategies key to halting rain forest loss.

• Logging interests cut down rain forest trees for timber used in flooring, furniture, and other items.
• Power plants and other industries cut and burn trees to generate electricity.
• The paper industry turns huge tracts of rain forest trees into pulp.
• The cattle industry uses slash-and-burn techniques to clear ranch land.
• Agricultural interests, particularly the soy industry, clear forests for cropland.
• Subsistence farmers’ slash-and-burn rain forest for firewood and to make room for crops and grazing lands.
• Mining operations clear forest to build roads and dig mines.
• Governments and industry clear-cut forests to make way for service and transit roads.
• Hydroelectric projects flood acres of rain forest.

Rainforests in different parts of the world often have similar species, but because they have developed separately for thousands of years, they each have their own characteristics. Both South American jaguars and African leopards have spotted skins that camouflage them in the dappled light of the forest floor. Like leopards, jaguars have rings of black spots on their coats, but they also have smaller spots within those rings.

Body structure: The jaguar is stockier and more muscular than the leopard, with a compact body, a broader head and powerful jaws.  The jaguar’s tail is also generally shorter than the leopard’s tail.

Fur pattern: Though jaguars and leopards both have coats that feature rosette patterns, a jaguar’s rosettes have spots inside them. Both jaguars and leopards can have either golden colored fur or appear black, which is called melanistic.

Body size: The leopard is considered the smallest of the four “big cats.” The other three are the tiger, lion, and jaguar.

Behavior: Jaguars and leopards can both swim very well.  Though jaguars love to spend time in the water, leopards will avoid it.

Jaguars are braver than leopards when it comes to facing off with another species that’s bigger.  Leopards tend to shy away at the sight of a bigger animal like a lion or hyena while jaguars will boldly stand their ground or even attack anaconda or large caimans in their native habitats.

Habitat range: In the wild, jaguars and leopards inhabit totally different continents. The jaguar once roamed from Argentina in South America all the way up to the Grand Canyon in Arizona.  Today, jaguars have been almost completely eliminated from the US and are endangered throughout their range, stretching down to Patagonia in South America.

On the other hand, leopards are found throughout most of Africa and Asia, from the Middle East to the Soviet Union, Korea, China, India, and Malaysia.

Strictly speaking, tropical rainforests should fall within the tropics — between the Tropic of Capricorn and the Tropic of Cancer. In fact, most are found even nearer to the equator. South America, Africa and Asia have large areas of rainforest.

CENTRAL AMERICA

This region was once entirely covered with rainforest, but large areas have been cleared for cattle ranching and for sugar cane plantations. Like other major rainforests, the jungles and mangrove swamps of Central America contain many plants and animals found nowhere else.  Central America is famous for its large number of tropical birds, including many kinds of parrots.

THE AMAZON

The Amazon jungle is the world’s largest tropical rainforest.  The forest covers the basin of the Amazon, the world’s second longest river. The Amazon is home to the greatest variety of plants and animals on Earth.  A 1/5 of all the world’s plants and birds and about 1/10 of all mammal species are found there.

AFRICA

Central Africa holds the world’s second largest rainforest.  To the south east, the large island of Madagascar was once intensively forested, but now much of it is gone. Africa contains areas of high cloud forest, mangrove swamps and flooded forests.  The island of Madagascar is home to many unique plants and animals not found anywhere else.

SOUTHERN ASIA

The rainforests of Asia stretch from India and Burma in the west to Malaysia and the islands of Java and Borneo in the east.  Bangladesh has the largest area of mangrove forests in the world. In Southeast Asia the climate is hot and humid all year round. In the mainland Asia it has a subtropical climate with torrential monsoon rains followed by a drier period.

AUSTRALASIA

Millions of years ago, Australia, New Zealand and the island of New Guinea formed part of a great forested southern continent, isolated from the rest of the world.   Today these countries contain many different species of animal that occur nowhere else. Undergrowth in Australia’s tropical forests is dense and lush.  The forests lie in the path of wet winds blowing in from the Pacific.

Rainforests are tropical evergreen forests. They have at least 4000mm (156 inches) of rain each year. The climate is warm and moist all year round, giving conditions in which green plants can produce huge amounts of vegetation, flowers and fruit. There is always plenty to eat for insects and the animals that, in turn, feed on them. The rainforest also offers an extraordinarily wide range of habitats for living things.

Rainforests are areas of extremely high biodiversity compared to other ecosystems. In the rainforests of Borneo, scientists have documented more than 15,000 plant species, including 2,500 species of orchids! Biologists estimate that tropical rainforests contain about 50% of the world’s terrestrial plant and animal species, yet they encompass only about 6% of the world’s land area.

Rainforests have 170,000 of the world’s 250,000 known plant species. The United States has 81 species of frogs, while Madagascar, which is smaller than Texas, may have 500 species. An area of rainforest the size of two football fields (one hectare) may have more than 400 species of trees, while an equal area of forest in the United States may have fewer than 20. Europe has 570 butterfly species, while Manu National Park, a single reserve in Peru, has 1,300 species.

Because rainforests are located in tropical regions, they receive a lot of sunlight. The sunlight is converted to energy by plants through the process of photosynthesis. Since there is a lot of sunlight, there is a lot of energy in the rainforest. This energy is stored in plant vegetation, which is eaten by animals. The abundance of energy supports an abundance of plant and animal species.

The canopy structure of the rainforest provides an abundance of places for plants to grow and animals to live. The canopy offers sources of food, shelter, and hiding places, providing for interaction between different species. For example, there are plants in the canopy called bromeliads that store water in their leaves. Frogs and other animals use these pockets of water for hunting and laying their eggs. Many species in the rainforest, especially insects and fungi, have not even been discovered yet by scientists. Every year new species of mammals, birds, frogs, and reptiles are found in rainforests.