Their howling can be heard five kilometers away. The aptly-named howler monkeys are among the largest of the New World monkeys. They live high up in the trees where they feed mainly on tender leaves. They are the favorite animal of Jorge Ferrer, a forest ranger in Colombia, who says they are very intelligent.

About "My favorite"

With all the talk of endangered species, the value of biodiversity and the usefulness of ecosystems, we sometimes forget why plants and animals are really worth protecting: because we love them, or depend on them for our own wellbeing. People from all walks of life and in all parts of the world have a favorite species. The reasons are many - perhaps because it is beautiful, or fascinating, or it helps them secure a livelihood. Meet some of these people and their favorites in our series "My favorite".