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Uakari

life science Maturity 11-13 Next article →

The uakari is a unique type of New World monkey.

Male uakari
Male uakari

These primates belong to the genus Cacajao. They live in the tropical forests of the Amazon basin. You can find them in Brazil, Colombia, Peru, and Venezuela. These monkeys are important for understanding how primates adapt to their environments. They are known for several very strange physical features. Their bodies are covered in long, loose hair. However, their heads are completely bald.

Male uakari
Male uakari

One of the most unusual things about the uakari is its proportions. Most monkeys have tails that help them balance. The uakari has a very short tail. It measures only 15 to 18 cm in length. This is much smaller than its head and body. The head and body together measure between 40 and 45 cm.

Male uakari
Male uakari

Because they have almost no subcutaneous fat, their bald faces look unusual. This lack of fat makes their faces look almost like a skull. They also have projecting lower incisors. These are large front teeth that stick out from the mouth.

These specialized teeth serve a specific purpose in their diet. Uakaris are primarily frugivores, which means they mostly eat fruit. However, they are different from other Neotropical frugivores. They can eat a large amount of unripe fruit. Their teeth allow them to process this hard food.

Male uakari
Male uakari

In addition to unripe fruit, they eat flowers and seeds. They also consume leaves, buds, and various invertebrates. When they move through the forest, they stay in the lower branches. They will climb up to the canopy to forage for food. They live in both small groups and large troops of up to 100 monkeys.

The most striking feature of the uakari is its facial color.

Male uakari
Male uakari

They have the most brilliant red facial skin of any primate. This red color is not just for looks. It is a signal of biological health. Evidence suggests that the red coloration reflects how healthy the primate is. This plays a major role in their social lives. Females choose their mates based on how red the male's face is. A brighter red face likely indicates a healthier individual.

Scientists recognize different groups of uakari species. There are four species currently recognized in the north-western Amazon basin. The bald uakari species group includes the white bald-headed uakari, the Ucayali bald-headed uakari, the red bald-headed uakari, and the Novaes' bald-headed uakari.

Male uakari
Male uakari

The black-headed uakari species group includes the golden-backed uakari, the Aracá uakari, and the Neblina uakari. These groups live in specific geographic areas. For example, the bald uakari lives north of the Amazon River. It is found south of the Japurá River in the Mamirauá Sustainable Development Reserve.

The black-headed uakari lives north of the Amazon and south of the Rio Negro. The Neblina uakari is found north of the Rio Negro. It lives west of the Rio Marauiá and east of the Casiquiare canal. The Aracá uakari is currently known only from the Rio Curuduri basin. Taxonomy, or the way scientists classify animals, can sometimes be debated. In 2014, researchers Ferrari et al. proposed a different way to group these monkeys. They suggested the Aracá uakari was a subspecies of the golden-backed uakari. They also suggested Cacajao ouakary was its own species. This new classification is not yet universally accepted by all scientists.

The history of the uakari is tied to the changing rivers of the Amazon. A phylogeographic reconstruction helps scientists understand their past. This study shows the ancestor of living uakaris dates back to 1.7 million years ago. These ancestors likely lived in the Solimões River area. As rivers underwent intermittent rearrangements, the monkeys spread out. This movement allowed them to diversify into the different species we see today. They continue to thrive in neotropical Amazon flooded or riparian forests.

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