These very small and large-eyed monkeys can be found across Central and South America, and have a very distinctive call which makes them easily recognizable those who hear it.
This is the only nocturnal monkey in the world. During the day they sleep in hollows of trees and dry palms, usually in transitional environments between the mature forest and the flood areas with dense undergrowth. They prefer the middle and high levels of the forest, between ten and twenty meters. You can recognize their call by the sound of soft clicks, often accompanied by a low-pitched, resonant sound of low frequency, like that of two heavy pieces of metal hitting each other.
On moonlit nights a single animal emits a series of shouts of one to three low-frequency whistles similar to those of an owl. For sleeping, they use holes in the trunks, as well as nests made with abundant foliage that provide shelter and protection. They live in groups of two to five individuals. They feed on fruits, insects and flower nectar. They are monogamous and, often, it is the father who raises the offspring.
In Peru there are two species of nocturnal monkeys, both are in a complicated situation. Many Amazonian people hunt this species for its meat, and the jibaros of the northeastern jungle use their teeth and fangs to make necklaces for ritual use.
Where they roam
Night monkeys live in Central and South America, from Panama to El Chaco (Argentina). A close relative, the brown nocturnal monkey (Aotus miconax) is endemic to Peru and is distributed in the high jungle (valleys of the Maronony Huallaga rivers) up to 3,200 meters.
Source: Guia de Identificacion de Especies de la Flora y la Fauna del Peru
Cover photo: Flickr