The northern owl monkey has a grooming claw on the fourth digit of both feet. Members of the genus Aotus are the only nocturnal New World primate. The legs of this species are longer than the arms, which assists in leaping. The northern owl monkey has large eyes, but lacks the tapetum typical of the nocturnal prosimians. The average body mass for this species is 1 kilogram, and no difference exists in body mass between males and females (Ford and Davis, 1992).
The northern owl monkey is found in Southern Venezuela and North-central Brazil (Nowak, 1999). This species lives in forests where the trees are evenly dispersed.
The northern owl monkey is a frugivorous species that also eats leaves and insects. The northern owl monkey prefers to eat small ripe fruit (Kinzey, 1997). An advantage of foraging at night is decreased competition from diurnal frugivores and the presence of larger nocturnal insects (Wright, 1989).This species spends all of its life up in the trees (Kinzey, 1997). The northern owl monkey becomes more active when the moon is bright (Wright, 1984), and they travel the same route during the night, so they may memorize routes when they travel when the moon is brighter (Wright, 1989)