Out of 250 species of primates in the world, 68 are in the Americas. It still remains a biological mystery how monkeys radiated to the New World. In Costa Rica there are only four species of monkeys, the Howler, the Capuchin, the Spider and the smallest, the Squirrel Monkey.
There are several anatomical differences between Old and New World primates, but the biggest and most fascinating is the prehensile tail. The prehensile tail works pretty much like a fifth limb. Monkeys can grab and hold with their tails and maintain their entire body weight. Seeing a Spider Monkey swinging through the tree tops, one almost imagines that it must have a hand at the end of its tail. Another difference is the position of the nostrils on the face. Old world monkeys (chimps, gorillas, etc.) have nostrils facing downwards (like humans) and new world monkeys have nostrils facing side to side. Again, a mystery as to why the new world monkeys developed in this way.
Naturalists like to find Monkeys in the rain forest, not only because they are so fun to watch, traveling through the treetops or lazily sleeping on a branch; but also because as troops of monkeys move through the forest, they flush out insects and lizards off the trees and plants. Birds fly along behind eating up the startled feast and on the ground, Terrestrial animals follow too from the understory, eating what is dropped to the forest floor. So if one follows a troop of Monkeys in the rain forest, there will be a better chance to see more wildlife than if you walk alone. Monkeys make great guides.
In Costa Rica often different species of Monkeys are found together, and they co-exist and don’t compete because their diets are different. Howler monkeys eat only plants and fruits, Spider monkeys like mostly fruit, Squirrel monkeys will eat a little of everything but they prefer insects, and Capuchin Monkeys will eat absolutely anything.
One of the most distinct and incredible sounds of the Tropical rain forest, is the loud scream of the Howler Monkey. Visitors to the jungle, will be awakened by an amazing howl emanating from the forest. Many people think it must be a ferocious jaguar, when in reality it’s just the gentle leaf eating Howler monkeys proudly responding to each other’s calls. The tiny adorable squirrel monkeys are very fun to watch. They are playful like children, chasing each other around the tree tops or often on hotel terraces. The adults and young join in games, pulling tails, wrestling, and chirping with delight. The spider monkeys are the jungles acrobats. They swing from vine to vine, tree to tree. They can make incredible leaps, with babies on their backs, and never seem to risk falling. Spider monkeys are among the very first mammals to disappear from an area if there has been deforestation. Spider monkeys require large territories to reproduce. The presence of Spider Monkeys in a particular forest, is a great indicator of the health and success of the area. The Capuchin or white faced monkeys are the most curious. They will get low on tree branches, to look at the tall intruders taking pictures of them from below. Be careful, if they are unhappy with your presence, you might get pelted with sticks.
Monkeys remain one of the main attractions for visitors to Costa Rica. If you visit the right areas, there is no need to even go into the rain forest, as monkeys have adapted to living in populated areas. If you wish to see all four species of monkeys, it is best to plan your trip for the Southern Pacific zone.