Tambopata National Reserve provides the ideal habitat for at least eight species of South American monkey. One of the best times to see monkeys in the rainforests of South America, including the protected forests of Tambopata, is in the rainy season, when many of the fruits which form an important part of their diet are readily available.
Of the eight species of monkey recorded in the Tambopata area, four are sighted regularly in the trees surrounding Tambopata Ecolodge, and among those species one of the most immediately identifiable is the red howler monkey (Alouatta seniculus).
This aptly named species of howler monkey has reddish fur and, in common with other howler monkey species, it is extremely vocal. At around 90 centimeters (36 inches) in length, the red howler monkey is also one of the largest primates in the Americas.
Howler monkeys are divided into a total of fifteen species. Their range extends from the forests of Central America to the Amazon basin of southeastern Peru. Slower moving than other, smaller species of monkey, howler monkeys travel through the trees of their tropical forest habitat using all four limbs and aided by their prehensile tails; in fact, their tails, which are as long as their bodies, are so strong they can support the monkey’s entire weight.
Howler monkeys are highly social mammals. They live in groups of between ten and fifteen individuals. On average, within these troops the ratio between the sexes is approximately one male to every four females. Aggression between howler monkeys, even among males competing for the attention of females, is extremely rare.
While most New World primates lack color vision, howler monkeys benefit from this adaptation. They also have an extremely acute sense of smell, and are said to be able to detect the presence of fruits and nuts from a distance of up to two kilometers (1.25 miles).
They are also of interest due to their unusual dietary habits; they are the only New World primate to survive on a diet largely composed of leaves, which they gather from the upper canopy of the rainforests they inhabit, far from potential predators. However, they are not strict folivores (“leaf eaters”), and will also feed on fruits and nuts. The normally vegetarian red howler monkey will even feed on the occasional bird’s egg.
But of course, it is the call of the howler monkey which truly distinguishes this family of fifteen species from other New World monkeys. They are said to be the world’s loudest land animal. Howler monkeys have an enlarged tongue bone, known as the hyoid, which enables them to produce such powerful vocalizations. Scientists believe that they use their call to protect their territory and ensure that other troops do not encroach upon their range. Essentially, each troop of howler monkeys will map out its territory by engaging in howling matches with other groups. Howler monkeys’ calls can be heard more than three miles (five kilometers) away. In the forests of Tambopata National Reserve, red howler monkeys are often heard at dawn or dusk, when their deep bark, roar or howl echoes through the trees.
Across their range, all fifteen species of howler monkey are threatened by hunting, destruction of their forest habitats, and capture for sale to the international pet trade or as zoo animals.