1. Population density for Aotus nancymai was 8.75 groups/kin 2 or 25 individuals/ km2.
2. Mean group size was 3.4 individuals, with a range of two to five individuals.
3. The social structure consisted of one reproductive pair with their offspring from up to three previous birth seasons.
4. The sex ratio within the social groups was 1:1, and the proportion of adults to immature in all groups was 55:45.
