Night Monkeys: Aotidae

Night monkeys are arboreal and live in family groups consisting of an adult pair and two or three offspring. During the day, the family sleeps in tree hollows or tangled vines. At night they forage for food throughout the forest levels, sometimes descending to the ground. They are especially active on moonlit nights, when they can see better. Night monkeys are adaptable. In Argentina, when the nights get cold at certain times of the year, the animals sleep at night and look for food during the day.

Night monkeys are monogamous (muh-NAH-guh-mus), having just one partner. The female gives birth to one offspring a year. The mother nurses the infant for up to eight months, but only carries the infant during the first week after birth and when nursing. The father provides almost all the child care. He carries the infant when the family travels through the trees. He also plays with the infant and the older offspring and guards them from predators, animals that hunt them for food. If the father dies, the older sibling, not the mother, assumes infant care. The young leave home at about three years of age.

Night monkeys scent mark territories with a behavior called urine washing. They wet their hands with urine, then rub them on their coats and the soles of their feet. The urine scent is transferred to the leaves and branches during their travels. They also communicate using secretions from scent glands on the chest and on the base of the tail. Conflicts between neighbors tend to occur when the moon is bright, perhaps because they can better see aggressive physical signals that include arching the back, erecting the fur, passing wastes, and urinating. The monkeys emit a variety of calls, including shrill cries, squeaks, and loud owl-like hoots that can be made louder by inflating the throat sac. Young males wishing to attract a mate hoot for long periods of time during a full moon.