The douroucoulis (AOTUS TRIVIRGATUS) (CEBIDAE) are nocturnal monkeys with good vision at night. Their ears are small and almost completely concealed in the fur. They live in forests and construct their nests for day-time in tree hollows. They are remarkable acrobats, adopted to running along tree branches. Their diet mainly consists of fruits, nuts, leaves, flowers, spiders, insects and small vertebrates. Douroucoulis live in pairs or in family groups, consisting of adult pair and their youngs. Females give birth to one young with weight at birth about 80 g. It lives with parents until sexual maturity which is attained at the age of 2 years.

These monkeys utter many vocal sounds, some of them similar to the calls of cats, jaguars and dogs.