FaunaHub

Douroucouli (Night Monkey) (genus Aotus)

MammalPrimateNocturnal

Night monkey or douroucouli (Aotus), a small primate with enormous round eyes.

Night monkey / douroucouli (Aotus).

Image: Marie Hale, CC BY 2.0, via Wikimedia Commons.

Overview

The douroucouli (genus Aotus), better known as the night monkey or owl monkey, is a small primate of the forests of Central and South America — and the only group of monkeys in the world that is truly nocturnal. Its most obvious feature is a pair of enormous brown eyes, adapted for seeing in low light, set in a round face with owl-like markings, which give it its “owl monkey” nickname.

Night monkeys live in close family groups built around a bonded male–female pair, and they are devoted parents: the father does much of the work of carrying and caring for the young.

Note: “douroucouli” / night monkey covers several Aotus species; details here describe the genus broadly. Treat general statements as approximate and verify against authoritative sources.

Habitat & Range

Night monkeys live in a range of forests across Central and South America — tropical rainforest, dry forest, and secondary woodland — from Panama down through the Amazon and beyond. They are arboreal, sheltering by day in tree holes or dense tangles of vegetation and emerging at night to feed and travel through the canopy.

Diet

Night monkeys are omnivores, feeding mainly on fruit, along with nectar, flowers, leaves, insects, and other small prey. They forage at night through the canopy, using their large eyes and good night vision to find food in the dark. By eating fruit and visiting flowers, they help disperse seeds and may aid pollination in their forests.

Behavior

Being nocturnal is what sets night monkeys apart from all other monkeys. Their huge eyes gather what little light there is (notably, unlike most nocturnal mammals they lack the reflective eye layer many night animals have, relying instead on very large eyes), and they are most active on moonlit nights. They live in small family groups — typically a mated pair and their offspring — and are strongly pair-bonded and territorial, advertising their presence with resonant hooting calls. Fathers are exceptionally involved, carrying the infant for much of the time and handing it to the mother mainly to nurse, a level of paternal care unusual among primates.

Human Interaction & Conservation

Night monkeys are affected by deforestation and habitat loss, and they have been captured for the pet trade and used in biomedical research, which has added pressure to some populations. Several species remain reasonably widespread while others, with smaller ranges, are of greater conservation concern. As wild, nocturnal primates with specialised needs, they are not suited to life as pets. Consult the IUCN Red List for species-specific status.

More photos of the douroucouli (night monkey)

A night monkey showing its big eyes adapted for nocturnal life.

Night monkey (Aotus trivirgatus).

Image: OpenCage, CC BY-SA 2.5, via Wikimedia Commons.

Frequently Asked Questions — Douroucouli (Night Monkey)

Why is the douroucouli called the 'night monkey' or 'owl monkey'?
Because it is the only group of monkeys that is truly nocturnal — active at night rather than by day. Its enormous brown eyes, adapted for low light, and round, owl-like face earned it the nickname 'owl monkey.' 'Douroucouli' is another traditional name for these same primates (genus Aotus).
How does the night monkey see in the dark?
Mainly through very large eyes that gather as much light as possible. Interestingly, unlike many nocturnal mammals, night monkeys lack the reflective layer (tapetum lucidum) behind the retina that makes other animals' eyes shine; instead they rely on their oversized eyes and a retina suited to dim light. They're most active on brighter, moonlit nights.
Do father night monkeys really raise the young?
Yes — they're famous for it. In night monkey families, the father takes on much of the infant care, carrying the baby for most of the time and passing it to the mother mainly so it can nurse. This high level of paternal care, within a strongly bonded pair, is unusual among primates and a hallmark of these monkeys.
What do night monkeys eat?
They're omnivores, eating mostly fruit along with nectar, flowers, leaves, insects, and other small prey. Foraging at night through the canopy, they use their large, light-sensitive eyes to find food in the dark, and by eating fruit and visiting flowers they help disperse seeds in their forest home.

Sources and further reading

Authoritative wildlife references used for general educational context. Conservation status should always be verified against current IUCN Red List data. External links open in a new tab.