Censusing primate populations in the reserved area of the Pacaya and Samiria Rivers, Department Loreto, Peru

Abstract

Four expeditions were made from February 1973 through March 1974 to the Samiria and Pacaya Rivers, which drain the zone between the Lower Ucayali and Huallaga/Maranon, principal constituents of the Amazon. This area is protected as part of the management program for the fishing ofArapaima gigas; however, there has been chronic hunting pressure from poachers, the government's guardians, and sailors, and, recently and most importantly, the petroleum exploration workers. Strip-censusing is extensively discussed. We employed a combination of three techniques: observations from our boat, observations from canoe or on foot, and intensive work in an area with mapped trails (Maldonado Peninsula, Samiria River). The Middle Samiria and Middle Pacaya were faunally the most rewarding. Relatively abundant wereSaimiri sciureus, Alouatta seniculus, probablyPithecia monachus, andSaguinus (probablyfuscicollis illigeri); somewhat less so wereCebus apella (often associated withSaimiri) andC. albifrons; Lagothrix lagotricha required deeper penetration, andAteles is seriously threatened (A. paniscus was seen andA. belzebuth was reported present). Also reported present wereAotus trivirgatus, Cebuella pygmaea, andCallicebus moloch andC. torquatus, though the latter two species may have been confused. Crude density estimates were developed from the Maldonado Peninsula data.