Family groups and sleeping sites were located by direct sighting during dusk and predawn censuses. Censusing was carried out from 1800 to 2030 hours and between 0300 and 0600 hours. Dusk censuses facilitated the location of groups, while dawn censuses facilitated the location of sleeping sites.
The height, form, composition, and characteristics of the sleeping sites were recorded. These observations were made at the sites by the principal author with the aid of a field assistant trained in tree climbing. Repeated observations were made of the use of the sleeping sites by Aotus and by other arboreal nocturnal mammals. The collection and analysis of biological samples included insects, plants, and some organic remains.
