FaunaHub

Uakari (Cacajao calvus)

MammalPrimateAmazon

Bald uakari (Cacajao calvus) with a bright red bald face, Peruvian Amazon.

Bald uakari (Cacajao calvus), Peruvian Amazon.

Image: Devon Vergiels, CC BY-SA 2.0, via Wikimedia Commons.

Overview

Uakaris (genus Cacajao) are distinctive monkeys of the western Amazon, unusual among South American monkeys for their short, stubby tails. The bald uakari (Cacajao calvus), shown here, is the most striking: a shaggy-coated monkey with a naked, vivid crimson face and head. That red face is more than decoration — it reflects the animal's health and plays a role in social and mating signals.

Uakaris are specialists of seasonally flooded Amazon forests and are expert at cracking open hard, unripe fruit and seeds that few other animals can use.

Conservation note: uakaris are threatened — the bald uakari is assessed as Vulnerable, mainly from habitat loss and hunting. Verify current status at iucnredlist.org.

Habitat & Range

Uakaris live in the western Amazon basin, especially in várzea and igapó — seasonally flooded forests along rivers and lakes — as well as nearby terra firme forest. The bald uakari is closely tied to flooded forest, moving through the canopy and adjusting its range as water levels rise and fall through the year.

Diet

Uakaris are seed predators and fruit-eaters with powerful jaws and teeth that let them bite into hard, unripe fruit and crack tough seed casings that are inaccessible to most other primates. They also eat ripe fruit, flowers, leaves, and some insects. This ability to use unripe fruit is especially valuable in the lean season when little ripe fruit is available.

Behavior

Uakaris are social and live in groups that can be large, moving energetically through the flooded-forest canopy with strong leaps. In the bald uakari, the intensity of the red face is linked to health — a pale face can indicate illness (such as malaria), so the bright crimson colour serves as an honest signal of fitness that influences mate choice. Uakaris are agile and active, spending most of their time high in the trees above the water.

Human Interaction & Conservation

Uakaris are remarkable, little-seen monkeys and an emblem of Amazonian flooded-forest diversity, but they are declining due to deforestation and hunting, and their reliance on specific flooded habitats makes them vulnerable. Protecting intact riverine forest is important for their future. Consult the IUCN Red List for species-specific status.

More photos of the uakari

A bald uakari showing its crimson face and shaggy coat.

Bald uakari (Cacajao calvus).

Image: Fábio Manfredini, CC BY 2.0, via Wikimedia Commons.

Frequently Asked Questions — Uakari

Why does the bald uakari have a bright red face?
The crimson face is an honest signal of health. The bare facial skin flushes red with good blood flow in a healthy animal, while illness — such as malaria — can leave it pale. Because a vivid red face indicates fitness, it plays a role in social standing and mate choice among uakaris.
Why do uakaris have such short tails?
Uakaris are unusual among South American monkeys in having short, stubby tails rather than the long (often prehensile) tails of many relatives. They rely on powerful limbs and leaping to move through the canopy, and the short tail is one of their most distinctive features.
What do uakaris eat?
Uakaris are seed predators and fruit-eaters with strong jaws that can crack hard, unripe fruit and tough seeds other animals can't open. They also take ripe fruit, flowers, leaves, and some insects. This skill with unripe fruit is a big advantage during the season when ripe fruit is scarce.
Are uakaris endangered?
The bald uakari is assessed as Vulnerable, and uakaris generally are declining. Habitat loss from deforestation and hunting are the main threats, and their dependence on specific flooded forests adds to their vulnerability. Current status should be checked against the IUCN Red List.

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.