In order to contribute to the research and protection of endemic populations of Callicebus, WCS carried out studies oft he distribution, density, group composition and behavioral ecology of both species within the framework of institutional cooperation agreements with the Municipal Government of Santa Rosa Yacuma. The data generated helped to identify priority conservation habitats and to create the Municipal Protected Area. Callicebus olallae habitat is located almost exclusively in the riverine forests of the Yacuma River, between Santa Rosa and Reyes, covering an area of only 162 km2; while Callicebus modestus is found in gallery forests and forest islands of the Santa Rosa, Reyes and San Borja municipalities. Populations of both primates are relatively small compared with other New World primates. The estimated population density of C. olallae is 11.8 individuals/km2, with an estimated total of 2,000 individuals, and for C. modestus is 13 individuals/km2 with a population of 20,000 individuals.
WCS also worked with the municipality in implementing the project “Conservation of the endemic titi monkeys of Beni (Callicebus modestus and Callicebus olallae) through outreach strategies” funded by Conservation Leadership Program (CLP). Talks and activities were conducted in all educational units of Santa Rosa and rural communities of the municipality and messages were broadcast through radio and television helping local people to increase their knowledge on the existence of the Municipal Protected Area and commitment to the conservation of the endemictiti monkeys.
With the collaboration of local communities of the Municipal Protected Area the information on the distribution of the titi monkey populations was also extended, identifying areas with the highest concentration of groups to focus conservation actions. Also, livestock areas and areas of burned pastures were identified, highlighting that these activities overlap with the habitat of the endemic titi monkeys, constituting the main threat to their conservation.