The mantled howler monkey

The mantled howler monkey

The mantle howler monkey is one of the largest monkeys in Central America, with males reaching a height of nearly a meter and a weight of up to 10 kg. It is one of 15 species of howler monkeys. Unfortunately, some of those species are endangered, mainly because of habitat loss and capture, for instance for sale to serve as pets. They get their English name “mantled howler monkeys” from the long hairs on their sides, which resemble a mantle. They can use their tail they as an extra limb to keep their balance. The tail also has a bare tip so they have a better grip around branches. With it, they can hold their entire weight and even feel with it as with their hands. The tail can be up to 5 times longer than the rest of their body. Especially young monkeys can be seen regularly hanging on to their tails, older monkeys use the tail more as a stabilizer.


In the wild, howler monkeys live to be 15 to 20 years old. The monkey’s diet consists mainly of leaves, which of course is not the best source of energy. Therefore, the monkey also spends large parts of the day while resting. Moreover, they should not eat too much from the same tree, as some leaves are slightly poisonous. So they are changing trees regularly. In addition to leaves, they also eat fruits, nuts and flowers. The monkeys’ sense of smell is very well developed, so well in fact that they can smell ripe fruit from 2km away. This is partly due to their round, wide-open nostrils. They rarely drink, as they get most of their moisture from food. Only when it is very dry they occasionally descend from their tree to search for water.


Why the roar?

Their roar is an energy-saving way to communicate with other monkeys in the troop, as well as with competitors. In the morning and evening, they roar to mark their territory, and their roar is answered by other groups nearby. And although howler monkeys are strictly vegetarian, and generally not known to be aggressive, that roar can scare people quite a bit. Not surprising when you know that the sound can be heard up to 5 kilometers away. To roar so loudly, the monkeys have a hollowed-out hyoid bone near their vocal cords. A bone that all monkeys have, but that in howler monkeys is enlarged several times. It is mainly the males that you hear; the females also vocalize but are not as loud.

Troop animals

By the way, such a troop of howler monkeys can have up to 40 members, although about 15 is more average. The monkeys in a troop are usually not related to each other, because as soon as they reach sexual maturity they are expelled from the troop. The troop has a dominant male and several females with whom it mates. Despite not having a set mating season, most births are in the second half of December and in January. Pregnancy lasts six months, after which the baby remains close to mom for about 4 months. From about 10 weeks of age, the young begin to search for food on their own.

A riddle for science

By the way, did you know that there had been almost no apes in South America? All the native ape species of the Americas died out in the Eocene, some 35 million years ago. The ancestors of today’s New World came from North Africa. And given the distance and lack of fossils, it is unlikely that they made that trip by land, so now the hypothesis is that they crossed the ocean. Notswimming, of course, but clinging to driftwood, or on islands of torn-off pieces of land. At that time the sea level was even lower, so the journey would have taken “only” about 10-13 days. Too crazy to be true? Only future discoveries and science will be able to tell!

Foundation Adopt Rainforest has been working for more than 10 years to protect the habitat of these special howler monkeys. Would you also like to contribute to this effort? You can easily do so by adopting a piece of rainforest for these wonderful animals. You can do this for as little as €2.50 for a square meter. Adopt here