Howler monkeys spend almost their entire lives in the treetops, rarely coming down to the ground. Their long prehensile tail works like a fifth hand - they can wrap it around a branch and hang from it, leaving both hands and both feet free to grab fruit and leaves.
The howl comes from a special hollow bone in the throat called the hyoid. Air passes through this chamber and produces that deep, booming sound. In Trinidad's forests, howling troops often call back and forth to each other, announcing where their group is feeding so other groups know not to come too close.
Red howlers eat mainly leaves, fruit, and flowers. Leaves are easy to find but hard to digest, so howlers spend a lot of time resting to save energy. If you spot one in the treetops, it might just be sitting very still - digesting its meal and enjoying the view.
Howler monkeys live in family groups led by one or two adult males. The whole group calls together, which makes the sound even louder and more impressive. Hearing it for the first time in a forest always makes visitors stop and look around in surprise.