Study...

Titi monkeys (Callicebus), morphologically cryptic primates, have been diffi cult to survey using traditional sighting-based line transect methods. Callicebus-species regularly engage in loud, ritualized singing bouts, which could allow for the use of alternate, potentially more accurate call-based survey methods to monitor populations. The Andean titi monkey, C. oenanthe, is endemic to a small region of northern Peru, an area subject to widespread and rapid deforestation and human colonization. We conducted a call-based survey of C. oenanthe at Tarangue, a 74 ha private reserve near Moyobamba. Triangulation of calls was used to map groups of titi monkeys on and around the reserve. 73 mapped calls were used to estimate the presence of between three and six groups per listening area- a total of 23 groups en-tirely or partially within the borders of Tarangue, yielding a