Scientific name: Aotus lemurinus grisemembra
Country: Colombia and north-eastern Argentina to Ecuador and Panama;
Continent: South America
Diet: Fruits - frugivore, nuts - nucivore, leaves, folivore, sap - gumivore, insects - insectivore, small vertebrates.
Food & feeding: Omnivore
Habitats: Tropical rainforest
Conservation status: Not evaluated
Relatives: Squirrel monkey
Description: Owl monkeys are one of the most unusual of the new world monkeys. They grow to 27-48 cm long with a tail length of 25-44 cm, and weigh 0.7 kg to 1.1 kg. Extremely large eyes give them excellent night vision. The fur is dense and woolly and the ears are hardly visible beneath the fur.
Lifestyle: Owl monkeys are the only nocturnal new world monkeys. They spend the day huddled together in hollow trees or dense vegetation and emerge at dusk to start feeding, moving from tree to tree through the forest, by way of branches and lianas.
Family & friends: Adult owl monkeys pair for life and become very stressed if separated from their partners. They live in small family groups composed of the adult pair plus up to three young. There seems to be a hierarchy within these groups: the adults will usually lead the way to new feeding locations.
Keeping in touch: They call together to other family groups using throat sacs to amplify their voices. The family group uses a range of hisses and squeaks to communicate during the night. Sometimes they also produce an owl-like hoot.
Growing up: A single infant is produced after a gestation period of 126-133 days. The male helps carry the infant for some of the time. The young owl monkey stays with the family group until about three years of age. At this age it leaves the group to find a mate of its own and form a new group.
Owl monkeys from Bolivia seem to be immune to malaria, whereas Colombian owl monkeys can and do contract malaria. Owl monkeys have played an important role in understanding how the parasite that causes malaria attacks the human body.