Fruit accounts for most of their diet, but they will also eat leaves, flowers, sap, and animal prey. They are arboreal, with different species preferring different levels and types of forest. They are monogamous, which is rare in mammals, and travel in family groups. The pair will share in territorial defense. There seems to be a breeding season, though not much is known about the behavior of the night monkeys.
Females give birth to a single infant which is carried by the male a good part of the time.
This involvement is said to be necessary because females are either pregnant or lactating year-round. Male and female offspring both emigrate from their family group by three years of age. Owl and night monkeys live about 20 years. A. miconax shares a habitat with a species of titi monkey. Subadult males will hoot at their territory border for 1-2 hours during a full moon to attract a mate.