Shortly after our arrival in Madidi in mid-1999, park ranger Radamir Sevillanos informed us about the presence of a large primate in the montane forests of Apolo, in the region of Asariamas, within the area of Madidi National Park. In September 1999 we were able to confirm the presence of the woolly monkey (Lagothrix cf. cana tschudii) near the community of Pata in the Apolo region. This record is the first confirmed for Lagothrix in Bolivia and the southern most of the distribution of this genus on the continent. The taxonomic status of the species is still in revision.
Like all species of the Atelidae family, woolly monkeys are big, muscular and appear particularly robust due to the thick gray fur covering their body, although some of them are darker with an almost black dorsal line. They measure around 52 cm with the prehensile tail over 63 cm, and weighs more than 7 kg. The head is relatively large and round, with well-developed jaws. They can live up to 25 years, and on average have one offspring every three years. In northern La Paz, groups of up to 13 individual shave been observed occupying large home ranges of about 10 km2.
Their diet is based on the consumption off ruits, leaves and flowers of a variety of plant species. Initial observations made by community members of Asariamas, with the support of WCS, described someplant species that are part of the diet of woolly monkeys: fruits of the palm heart (Euterpe sp.), fig fruits (Ficus sp.), Bacury-pary (Garcinia macrophylla), bromeliads (Bromeliaceae) and custard apple (Annonaceae).
Assessments by WCS on Lagothrix distribution innorthern La Paz concluded that this monkey is concentrated in the Apolo region of Madidi, over 700 meters above sea level. The records of this primate for Bolivia have only been confirmed in high mountain forests, valleys and incense forests within the protected areas of Madidi and Apolobamba between 700 and 2000 masl, and as such it is considered as Endangered in the Bolivian Vertebrates Red Book.