Red colobus and Diana monkeys often share forest territory in the Ivory Coast’s Taï National Park. They live peaceably together because they have different diets; Dianas eat ripe fruits and insects, while red colobus prefer young leaves, flowers, and unripe fruit. Some biologists have theorized that the alliance protects against predators. A larger group has more eyes to spot a lurking leopard. And if that leopard does catch lunch, lunch is much less likely to be you if you’re in a larger group. Now two behavioral ecologists have found evidence that while predation has indeed forged the alliance, the predators driving the monkeys together are not leopards but chimpanzees.
Chimpanzees hunt for meat late in the rainy season; earlier in the season, when their staple plant foods are less abundant, the chimps must break up into smaller groups and forage over wider areas. Red colobus monkeys--which are about twice as ...
