Ecological survey of the night monkey, Aotus trivirgatus, in Formosa Province, Argentina

Transect surveys were carried out in northern Argentina during October and November 1977 in order to determine the distribution and abundance ofAotus trivirgatus. The monkeys were seen in pairs with one to two recent young and occurred at a density of approximately six family groups/km².Aotus was only found in relatively moist, riparian, low forests. Some life history traits, such as diurnal activity and the lack of tree-hole use, are distinctive compared to more northern populations.