There are eight species of night monkeys, also commonly called douroucoulis or owl monkeys, found from Panama to Peru, Bolivia, and northeastern Argentina. Douroucoulis are the only nocturnal monkeys in the New World. They are small monkeys found exclusively in forests. They are characterized by large eyes, flat, rounded faces, and dense, woolly pelage.
- Nowak, R. 1991. Walker's Mammals of the World, Volume 1. Baltimore: The Johns Hopkins University Press.
- Cawthon Lang, K., E. Fernandez-Duque. 2005. "Primate Factsheets: Owl monkey (Aotus) Taxonomy, Morphology, & Ecology." (On-line). Primate Info Net. Accessed November 16, 2007 at http://pin.primate.wisc.edu/factsheets/entry/owl_monkey.
- Martin, R. 2004. Night Monkeys (Aotidae). Pp. 135-142 in M Hutchins, D Thoney, M McDade, eds. Grzimek Animal Life Encyclopedia, Vol. 14. Detroit, Michigan: Thomson Gale.
- Wilson, D., D. Reeder. 2005. Mammal Species of the World. Baltimore: The Johns Hopkins University Press. Accessed November 16, 2007 at http://nmnhgoph.si.edu/msw/.