A quarter-century of tracking wild owl monkeys, often referred to as night monkeys, in Argentina has turned up something unexpected: the small, leaping primates are getting heavier. And researchers ...

For decades, monkeys from the Colombian Amazon have been used in biomedical research and returned to the wild—now researchers want to know what happens after that. Of the 11 species of Night Monkeys ...

Moonlight movers: Night monkeys in Colombia adjust their movements based on lunar cycles, showing remarkable sensitivity to ambient light and canopy cover. Maternal influence: Young chimpanzees and ...

An ongoing outbreak of yellow fever in Colombia is sickening and killing rare and threatened monkey species in captivity, a new study shows. Between February and May 2025, authorities reported eight ...