Diana monkeys live in the upper canopy of tropical rainforests, leaping between branches high above the forest floor. They live in groups of around 20–30 individuals, usually led by a single adult male who keeps watch for danger. When a predator appears, he gives a specific alarm call that other animals in the forest — including other species of monkey — understand and react to.
This cross-species communication is one of the most fascinating things about Diana monkeys. They have been studied sharing alarm information with other monkey species, almost as if they are speaking a language that forest animals have learnt to understand. Different calls mean different things: 'eagle overhead' sounds different from 'leopard on the ground'.
The Diana monkey feeds mainly on fruit, leaves and insects. Their brightly coloured markings help group members spot each other easily through the leafy canopy. Sierra Leone's forests are among the few remaining places where Diana monkeys are still found in healthy numbers, which is why protecting those forests matters so much.