Manuel Antonio, Costa Rica is the home of the loudest monkey in the world. The common name is howler but the locals call them "congos." They often sleep in the trees next to our bed and begin to howl at about 4:30 A.M. To some this might seem like a nuisance but my husband and I just smile because it reminds us how happy we are to be here instead of south bound on the 405 freeway in L.A. The male howler has an enlarged hollow bone near his vocal chords that amplifies his calls. Howlers are the largest and most aloof of the primates in Manuel Antonio. They choose the tallest trees and spend most of their time in the upper branches. They live on a leafy diet, which doesn't provide an abundance of energy, so they rest and sleep a lot. Their black fur, the distance factor, and back lighting from the sun in the trees make them a challenge to photograph, so bring a zoom lens for your camera.

Costa Rica has four species of monkeys: the Mantled Howler, White-faced Capuchin, Red-backed Squirrel and Spider. All were once found in Manuel Antonio until a yellow fever epidemic in 1953 wiped out the spider monkey population. If you spend a week here you'll likely see the three species that remain.

The capuchin's local name is "Cara Blanca," (white face). They're the most dexterous of all primates. They manipulate objects so well there's a nonprofit organization called Helping Hands based in Boston that trains capuchins to help paraplegics and quadriplegics. They can brush your teeth, scratch an itch, feed you with a straw, and even pop Casablanca into the DVD player.

The endangered red-backed squirrel monkey, locally known as "mono titi," is the smallest of Costa Rica's primates. This particular subspecies only exists in and around Manuel Antonio National Park and their estimated population is a mere 1300-1800. What makes them unique is their peaceful nature. Neither males nor females appear to be dominant over each other, whereas the other subspecies of squirrel monkeys squabble on a regular basis. Like the capuchin, red-backed squirrel monkeys live on a diet of fruit, insects, leaves and stems. They often play on our roof and on occasion mate on our terrace table.

An important issue with monkeys in Manuel Antonio is that tourists feed them. I once saw a tourist hand a potato chip to a capuchin. The capuchin slapped his hand, snatched the bag of chips and ran up a tree. Besides being outwitted by a monkey, this is wrong on so many levels. Irregular feeding makes monkeys aggressive toward humans as they look to them for food. Recently after my daughter and a friend had gone souvenir shopping a capuchin tried to snatch their bags no doubt assuming there was food inside. Feeding monkeys disrupts their normal foraging patterns as they gravitate toward the "easy" food. Now, I'm not saying monkeys are going to chase you around town, this was a highly unusual situation, but why forage for food when someone will deliver it?

Feeding monkeys can also be fatal to them. Humans can transmit diseases from their hands to monkeys who lack immunity. Although there are education programs in place this continues to be a problem. Unaware tourists arrive every day. Sometimes they see others feeding the monkeys and think it's all right. Why not be part of the solution?

So now that you know feeding the monkeys is bad for them, how do you find them when you're visiting densely forested Manuel Antonio? They can often be found by the beach around dusk as they head for their favorite trees to nest for the night. They can be found in the hillsides near your hotel or vacation rental home. You can use techniques I learned from orangutan trackers in Borneo. Be still, watch and listen. First, watch for the movement of branches in the trees. Next, listen for food falling to the forest floor, then for each monkey's distinctive vocalization. Squirrel monkeys can sound like chirping birds; capuchins can sound like mewing kittens. As for Howlers, well, there's no mistaking them. Their thunderous vocalizations will rock your world - literally.