Experts believe that more than 50 per cent of the world's 10 million plant and animal species are found in the rainforest, including 40,000 plant species and more than 50 million types of insects. In this environment, inter-species competition is fierce. Natural biodiversity has created "resource partitioning," which minimises competition between similar species by ensuring that some animals prefer the resources found in a specific area, while others limit their search to another. However, competition for resources and food in particular remains a driving force in the struggle for survival.
Among the mammals in the rainforest are several species of primates. With the exception of the omnivorous chimpanzee, the other apes all compete for food. The gorilla and the lar gibbon feed primarily on leaves, fruit and bark, while the orang-utan and spider monkey survive by eating leaves, fruit, nuts and seeds and insects. Birds like the great hornbill and the hoatzin, the parrot, the toucan and the cassowary all compete equally for the fruit, insects, nuts and seeds.
Fruit is one of the main sources of food for the animals of the rainforest. More than 3,000 types of fruit grow in the forest, and at least 2,000 are suitable for human and animal consumption. Other sources of food for the animals are leaves, tree bark, nuts and seeds, and insects and smaller animals for the predators. The types of food needed by different species may come from a common source in the rainforest. A flowering tree, for example, may provide fruit, bark and leaves for the primates, flowers to attract insects that feed the birds, and seeds that fall to the ground and provide food for ground dwellers like the rodents that inhabit the forest floor.
Although all these species survive on similar diets, resource partitioning minimises competition between two species by ensuring a preference for a certain type of food. Spider monkeys, for example, spend most of their time high up in the forest canopy, eating fruit, leaves and insects found in the treetops. Poison arrow frogs subsist almost entirely on insects, but as they are mostly confined to the ground, they don't compete with the spider monkey. The animals have adapted to survive on specific types of food to lessen the competition for scarce resources.
Rainforests are being destroyed at the rate of 1 1/2 acres per second as a result of logging, agriculture, mining and industry and tourism. Although the forests once covered 14 per cent of the earth's surface, they now comprise only 6 per cent, and experts estimate that in less than 40 years they will be lost. This rapid destruction makes food sources even scarcer and increases the competition for food among animals, which are becoming extinct at the rate of 35 species per day.