Howler Monkey
Alouatta seniculus

They are called howler monkeys because of the way they howl their lungs out. Actually it sounds more like a roar than a howl and this is a territorial sound to tell all the other animals in the forest that the forest is their territory; they are telling the others where they are and that the others should stay clear!

This is a lot easier than fighting to maintain one’s territory. There are certain things that may set howler monkeys off such as low flying airplanes, thunderstorms, and quite often when a large group of people are in the rain forest: they perceive us as fellow monkeys who are invading their territory. This howl, which can be heard at a mile’s distance, comes from the bony voice box, which looks like an oversized pouch below their chin.

Another interesting thing are their tails, which are prehensile, that is their tails can grasp objects or grasp branches to hold their full body weight while they are feeding. These grasping tails are only found in New World primates, monkeys found in South and Central America.

No monkey from Africa or Asia has a tail like this. If you can get a close look at it you will also notice that the last 6-9 inches of the underside of his tail is just skin. This skin has fingerprints and each howler has a unique set of prints just as we humans have unique handprints. They can grasp objects as small as grapes so their tails function as third hands. Pretty handy when you live all your life in the trees.