They can use this tail as an extra arm to grip or even hang from branches—no Old World monkeys have such a tail. A gripping tail is particularly helpful to howler monkeys because they rarely ...

What is a woolly monkey? An animal called a woolly monkey seems like it should live in the frozen north, not the sweltering Amazon Basin. But the thick coat of fur covering these large primates ...

My adventure of a lifetime began in 2015 when I was asked to follow the tree-top lives of Costa Rica’s gravity-defying howler monkeys (Alouatta palliata palliata). Image by Justine Allan.