Discover the Bald Uakari: The Amazon’s Red-Faced Primate Marvel

Bald Uakari

Scientific Name: Cacajao calvus
Geography: Amazon region in South America
Habitat: Forested habitats
Diet: Herbivores and frugivores
Behavior: Very social creatures
Life Span: 15-20 years
Conservation Status: Vulnerable
Threats: Harpy eagles, boa constrictors, tayras, and ocelots

The bald uakari (Cacajao calvus) is a unique looking primate with a bright red face that lives in the Amazon rainforest. These primates are also known as bald-headed uakaris.

Concerns over the conservation status of this New World monkey species have grown over the last decades. Currently, deforestation of the Amazon rainforest has caused many animals to retreat into smaller and more fragmented ranges.

Bald uakaris are mainly found on the border of Peru and Brazil. They possess some interesting characteristics that set them apart from other South American primates. 

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Bald Uakari Taxonomy and Classification

Bald uakaris are primates that fall under the dry-nosed primates suborder Haplorhini. They belong to the infraorder Simiiformes, which consists of New World monkeys.

There are five New World monkey families. Bald uakaris belong to the family Pitheciidae. This family also includes titis and saki monkeys. Monkeys in this family are native to South America. Uakari monkeys are in the genus Cacajao.

There are four main subspecies of bald uakaris recognized. These subspecies include:

• White bald-headed uakari (Cacajao calvus calvus)
• Red uakari (C. calvus ucayalii)
• Novaes’ bald-headed uakari (C. calvus novasei)
• C. calvus rubicundus

Another species in the genus Cacajao that’s closely related to the bald uakari is the black uakari. Their scientific name is Cacajao melanocephalus.

This species has its own subspecies, including C. melanocephalus melanocephalus and C. melanocephalus ouakary. Unlike bald uakaris, black uakaris possess a black hairless face. 

Geographic Location and Distribution

Bald uakaris are native to the Amazon region in South America. The largest populations are found along the Yavarí (also called Javari) and Ucayali rivers. These rivers straddle the border of Peru and Brazil.

Their range once extended into southern Colombia. However, deforestation and other factors may have caused them to go extinct in this area.

The bald uakari range is limited and fragmented due to deforestation. They thrive in tropical rainforests that experience seasonal or year-round flooding. Along with inhabiting riversides, these primates also live around lakes within the Amazon.

Their preferred habitat is amongst aguaje palm trees and várzea forests. These are seasonal floodplains found in the Amazon region. Seasonal flooding in this region is important for the diet and lifestyle of the bald uakari.

Bald Uakari Characteristics and Appearance

Bald uakaris are hard to miss because of their bright red face. Their face is hairless, while their body ranges in fur color. Uakari subspecies are distinguished by the color of their fur.

These primates are small to medium-sized. They typically weigh up to 7.75 pounds (3.5 kg) and can grow to up to 22.5 inches (57 cm) long.

The bright red face of bald uakaris is caused by a number of things. They have a thinner epidermis than other primates. Their face also has a higher concentration of small blood vessels called capillaries.

The brightness of a bald uakari’s face indicates its health. Paler faces can indicate that a bald uakari is sick. This can be common because primates in the Amazon region are at high risk of malaria.

Healthy bald uakaris have the most pigmented faces. Redness levels also help with sexual selection.

Females are more attracted to males with bright red faces. Females with higher estrogen levels have a more red face. On the other hand, males with redder faces have higher testosterone levels.

Fur color can range from brown, reddish-brown, orange, or shades of blonde. White bald-headed uakaris have a more blonde, pale fur coat.

Uakaris come in many colors! Cacajao calvus rubicundus have a red coat, while red uakaris have a reddish-gold coat. And Novaes’ bald-headed uakaris have an orange fur coat.

Unlike many primates in South America, bald uakaris have very short tails. These tails are non-prehensile. This means they can’t use their tails to grab onto things. Their short tails are simply decorative, so it doesn’t offer any advantages.

Bald Uakari Diet

Bald uakaris are herbivores and frugivores. This means their diet only consists of plant matter, fruits, and seeds. What they eat can depend on the season.

Bald uakaris mainly feed on seeds and fallen fruits and leaves during the dry season. The dry season in the Amazon takes place between August and November.

The wet season is between December and May. During this time, bald uakaris feed on fruits and leaves in the forest canopy.

The time of year largely affects the lifestyle of the bald uakari. They’re primarily arboreal during the rainy season. Water levels on the ground are too high for them. This is why they spend most of their time up in the trees.

Once the rainy season passes, bald uakaris become terrestrial. They travel down to the forest floor to forage for food. Observations conducted determined that uakaris feed on up to 120 plant species.

The jaws and teeth of the bald uakari are designed to bite through seeds and fruits with hard exteriors. They also enjoy snacking on Brazil nuts and various insects, such as caterpillars and ants.

Behaviors and Group Dynamics

Bald uakaris are very social creatures. They have several types of communication methods. They use facial expressions, body language, vocalizations, and pheromones to communicate. Researchers have observed bald uakaris use at least 10 facial expressions.

To ward off predators, bald uakaris let out a high shrieking noise. Pheromones are scents released to attract mates.

Bald uakaris have also been observed wagging their short tails. Tail wagging can be a sign of excitement or threat. When threatened, tail wagging is often accompanied by clicking noises and raised fur.

Bald uakaris live in groups called troops. One troop can have up to 30 individuals. Larger troops can have up to 100 members. Bald uakaris usually split up into smaller groups to forage for food.

A troop’s home territory can be as large as 2 square miles (5.2 sq km). Troops may travel between 3-5 miles (4.8 – 8.0 km) in just one day. 

These primates spend equal amounts of time resting, eating, foraging, and traveling. They’re diurnal creatures. This means they’re active during the day.

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Mating and Reproduction

Many primate species are polygynandrous. This is a type of mating system in which the males and females have multiple partners throughout their lifetime. This is a relatively common mating system for primate groups that consist of multiple males and females.

Bald uakaris are mainly monogamous. They usually only mate with one other partner in their lifetime. But some individuals may have multiple partners.

Bald uakaris breed between October and May. Breeding occurs at the end of the dry season and in the wet season because ample food sources are available.

Females give birth to one young about every two years. The gestation period is six months. Like many infant primates, they’re highly dependent on their mother for the first few months.

Mothers spend most of their time caring for their young for the first five months after birth. They feed on milk until they’re old enough to transition to fruits.

Young bald uakaris begin weaning off their mother at about five months old. They’re introduced to a soft fruit diet at this time. Females reach sexual maturity at three years old, while males reach sexual maturity at six years.

Once young bald uakaris are completely independent, males will leave the troop in search of another. Females stay in the troop they were born in.

Conservation Status of the Bald Uakari

Bald uakaris are listed as Vulnerable on the International Union for Conservation of Nature Red List (IUCN). This status is based on the last assessment of the species in March 2020.

Vulnerable species are those at risk of extinction in the wild. The current population trend of bald uakaris is decreasing. However, populations are not yet severely fragmented.

Deforestation and wood harvesting are the main threats of the bald uakari species. Humans also hunt bald uakaris. Their meat is used for consumption in Peru. In Brazil, bald uakari meat is used as bait to hunt other animals.

The Mamirauá Reserve for Sustainable Development in Brazil has tried to bring awareness to the species in hopes to raise conservation money. 

Primate watching programs open to tourists were considered to help with conservation efforts.

Black-headed uakaris have experienced some success in making a comeback. The IUCN assessed this species in June 2016 and classified them as Vulnerable. The species was reassessed in March 2020 and determined to be of Least Concern.

Fun Facts

Bald uakaris play an important ecological role

Bald uakaris are beneficial to the Amazon biome because of their food habits. The fruits and seeds that these primates eat are dispersed through their feces.

Seed dispersal helps promote biodiversity. It also helps maintain healthy plant populations that bald uakaris and other Amazon animals depend on.

Bald uakaris are close relatives to humans

Bald uakaris help researchers perform important studies on various diseases and vaccines. Due to their close relation to humans, they can provide insight on things like malaria and diabetes.

Bald uakaris are quadrupeds and bipeds

Most primates are quadrupeds. This means they use all four limbs to travel. Bald uakaris utilize all their limbs to walk on the forest floor or climb in trees.

They’re also considered bipeds. This means they have the ability to walk on their hind legs. They tend to walk with just two legs when exploring the forest floor.

Young bald uakaris like to play games

Bald uakaris are known for being intelligent, active creatures. Young bald uakaris have been observed engaging in games with each other.

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Bald Uakari FAQ