Primate diversity in forests on the eastern side of the Ucayali River, Peruvian Amazon

Abstract

In the Peruvian Amazon there are areas with gaps in information on biodiversity, one of them being the eastern side of the Ucayali River in the Department of Ucayali, which motivated the conduct of transect censuses in the area delimited by the basins of the Callería and Sheshea rivers to determine the diversity of primate species that inhabit them and identify threats to their populations. The censuses were carried out at eight sampling sites between June and July 2015, July and August 2016, November 2017 and August 2020. In 88 days of travel, 415 groups corresponding to 22 species were recorded, with Saimiri boliviensis being the most common, followed by Sapajus macrocephalus, while Ateles chamek was the rarest. Plecturocebus sp. would be a new species for Peru and was recorded in the upper basin of the Abujao River. The largest groups were S. boliviensis and Cacajao ucayalii, while the smallest group was Ateles chamek. Additionally, three enclaves were discovered where Cebus yuracus, Plecturocebus discolor, Leontocebus illigeri and Leontocebus leucogenys were recorded, species that have their original distribution on the western side of the Ucayali and Amazon rivers. Among the main threats, hunting and deforestation for various purposes would be responsible for the reduction of the populations of the so-called large primates, particularly A. chamek, which is on the path to extinction in the study area.