Abundance and primate density in Gurupi Biological Reserve, Maranhão, Brazil

Abstract

ABSTRACT The Belém area of endemism has only about 30% of its original forest cover remaining, and what remains fragmented and degraded. The Gurupi Biological Reserve (REBIO Gurupi) covers approximately 270,000 hectares in the state of Maranhão. It is the only federal strictly protected area that has populations of two critically endangered species: Cebus kaapori (Ka'apor capuchin) and Chiropotes satanas (black bearded saki). The first survey of primate abundance in this protected was in 1992. In this study we provide data on the relative abundance of these primates 21 years later, using the same methodology, the linear transection method. Surveys were carried out along a network of tracks in three different locations in the reserve. From 9-16th October 2013, we walked 320km of trails and obtained 101 sightings of five of the seven species present; Saimiri collinsi and Aotus infulatus were not recorded. With 1 group/10km Saguinus ursulus was the most abundant, followed by Sapajus apella with 0.91 groups/10km, and Alouatta belzebul with 0.72 groups/10km. Cebus kaapori and Chiropotes satanas, were also recorded, but with lower encounter rates of 0.25 and 0.28 groups/10km, respectively. These results are similar to those found in 1992, but the encounter rate for Cebus kaapori was higher in the present study. Despite being a protected area, the Gurupi still suffers from threats such as hunting, illegal logging, deforestation, and fire. These threats significantly impact the primate populations there, especially the two that are critically endangered.