Bald Uakari Monkey

The bald uakari (Cacajao calvus ucayalii) is an Amazonian primate with peculiar features: it has a bright red, bald face, a short tail, and ruddy fur. This monkey is highly specialized and is found mainly in palm tree habitats. It has a limited distribution range, and the largest known populations are found at the mouth of the Yavarí Mirín river, in the border between Peru and Brazil. Its red face is an indicator of good health, and it reflects a balanced diet of fruit, seeds, flowers, and insects. The bald uakari lives in family groups, although young males will often desert to establish their own families.

The bald uakari serves as the flag species for the Conservation Concession Lago Preto Paredón, where bald uakari research has taken place since 1992 when a WCS team explored the area for the first time. As with other primates, the bald uakari are vulnerable to indiscriminate hunting and their populations are badly hurt when they are harvested. Fortunately, since WCS and DICE implemented conservation actions in the concession, such as management, monitoring, and research, the bald uakari population of Lago Preto Paredón has increased until it was considered stable and viable in 2011.

The bald uakari is the only primate in the Yavari valley to be included in the IUCN Red List as Vulnerable (VU). It has also been categorized in the same way by the Ministry of Agriculture and Irrigation due to its rapid deforestation/degradation and its indiscriminate hunting. WCS has supported studies about its ecology, social behavior, functional biology of its red face, and population genetics. These are fascinating aspects of bald uakari biology that are intimately linked to its conservation and ecosystem health.


10 facts about the bald uakari:
  1. Its defining feature is its bald head and its bright red face.
  2. It weighs between 2.75 and 3.45 kg, while its body length (including head) averages at 45.6 cm for males and 44 cm for females.
  3. Its tail is short, averaging at 15 cm, less than half its body length.
  4. The bald uakari’s fangs are well developed in order to break open thick fruit skins.
  5. Its distribution is irregular and endemic to between the Yavarí and Ucayali rivers.
  6. Its favorite habitat are those areas with aguaje palm trees (Mauritia flexuosa).
  7. To sleep, bald uakari monkeys will gather in groups of 50-200 individuals.
  8. They can live up to 20 years.
  9. They mate between October and May, when the female attracts the male through olfactory stimuli.
  10. Bald uakari monkeys have offspring every two years.


Top photo: Walter H. Wust