Howler monkeys are abundant in the Amazon rainforests and as the name indicates, they are quite a vocal group of primates. There are a number of howler monkey species living in South America, from the mantled howler and the black howler to the red-handed and Colombian red howler. The black howler is one of the largest species of the New World monkeys, standing at just over three feet tall with a tail about the same length.

The call of the howler monkey is a guttural, raspy sound, more similar to a bark than a howl. Adult males are the most vocal among their groups, but when one starts shouting the rest usually follow suit. The calls serve to ward off threats and establish territorial borders. The noise these monkeys make can be heard from more than a mile away, and if you spot one, you'll likely soon notice a number of other howlers nearby.

They stick to the trees, so guests on our Amazon tours should check the branches overhead during excursions. Prehensile tails help howler monkeys navigate the branches high up in the rainforest canopy. This is the ideal place for howlers, as their diet consists of food they can find in the treetops, but some howler monkeys make their homes in mangrove swamps and are excellent swimmers. For the most part, howlers are vegetarians. While they typically eat leaves and fruit, these monkeys have been known to snack on insects and flowers as well.

Howler monkey groups typically consist of one or two adult males, a few females and their young. These primates live to be between 15 and 20 years old, and females typically first give birth when they reach about five years. Some groups may consist of males seeking to overthrow patriarchs of established howler families, though this is fairly uncommon. When the young reach adulthood, they will leave their families to establish new groups or attempt to take over other groups.

Howler monkeys are a common sight in the Amazon, and even if you can't see them on your small group tour, you'll likely be able to hear their cries. The best times to spot these primates are in the morning and evening, when they are most active. They typically nap in the trees during midday when temperatures are hottest.